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This paper has integrated new and past data to elucidate how lipid, protein and glycogen metabolism contribute to generating the ATP required by the southern hemisphere lamprey Geotria australis during its ~ 13-15 months, non-trophic upstream spawning migration. Energy is required for maintenance, swimming, the development of gonads and secondary sexual characters and spawning and post-spawning activities. Plasma and muscle metabolites were measured in animals subjected to an exercise-recovery regime at the commencement and completion of the spawning run. The present study demonstrated the following. At all stages of the migration, plasma glucose and glycerol concentrations increased during exercise and then declined, whereas plasma FFAs exhibited the reverse trend. During exercise and recovery, alanine declined and ammonia increased in the plasma of early migrants, while the opposite occurred in mature males. Following exercise, muscle alanine rose and then declined in early migrants, but declined and then rose in mature males. The composite data emphasise that, while the same catabolic processes are employed by both sexes early in the migration, when animals are immature, they differ markedly between the sexes as they mature and then spawn, reflecting their different demands. Energy is supplied predominantly via anaerobic metabolism in early migrants, but by anaerobic and aerobic metabolism in prespawning females and by aerobic metabolism in mature males and spent females. Although proteolysis is limited early in the migration, it is employed extensively during maturation and particularly by females, which undergo a substantial reduction in length in the lead-up to spawning.

The pouched lamprey, Geotria australis Gray, 1851, has long been considered monotypic in the Geotriidae family with a wide southern temperate distribution across Australasia and South America. Recent studies have provided molecular and morphological evidence for a second Geotria species in South America; Geotria macrostoma (Burmeister, 1868). The aim of this study was to determine morphometric and physical characteristics of adult G. macrostoma that further differentiate this re-instated species of Geotriidae from G. australis. The diagnostic features discriminating immature adult G. macrostoma from G. australis when entering fresh water, are distinct differences in dentition, oral papillae and fimbriae counts and differences in coloration. In addition, G. macrostoma display greater growth of the prebranchial region and oral disc and has a deeper body depth and higher condition factor. All current ecological knowledge of the genus Geotria is based on Australasian populations, which may not be applicable to G. macrostoma. To ensure the conservation and protection of the Patagonian lamprey as a re-identified species, further investigations are needed to understand its life history, biology and ecology throughout its range.

The characteristics of detached macroalgae (drift) in nearby highly eutrophic and mesotrophic estuaries in south-western Australia are compared to elucidate the magnitude and types of changes that occur in macroalgal drift when estuaries receive excessive nutrient input. Drift characteristics in the large basins of the microtidal, eutrophic Peel-Harvey and mesotrophic Swan-Canning, which is not subjected to large nutrient inputs directly from agricultural land, differed markedly. Biomass (dry weight) in mesotrophic estuary was dominated by rhodophytes (92%), particularly Laurencia and Hypnea, and in eutrophic estuary by opportunistic chlorophytes (68%), especially Chaetomorpha and Ulva. Prevalence and biomass of drift were far greater in the eutrophic estuary, particularly during summer and autumn when macroalgal growth rose sharply. Macroalgal biomass in the eutrophic estuary was positively related to salinity. These results facilitate predictions of how climatic and other anthropogenic changes influence extent of macroalgal growth and thus change the estuarine environment.

Lampreys are extant members of the agnathan (jawless) vertebrates that diverged ~500 million years ago, during a critical stage of vertebrate evolution when image-forming eyes first emerged. Among lamprey species assessed thus far, the retina of the southern hemisphere pouched lamprey, Geotria australis, is unique, in that it possesses morphologically distinct photoreceptors and expresses five visual photopigments. This study focused on determining the number of different photoreceptors present in the retina of G. australis and whether each cell type expresses a single opsin class. Five photoreceptor subtypes were identified based on ultrastructure and differential expression of one of each of the five different visual opsin classes (lws, sws1, sws2, rh1, and rh2) known to be expressed in the retina. This suggests, therefore, that the retina of G. australis possesses five spectrally and morphologically distinct photoreceptors, with the potential for complex color vision. Each photoreceptor subtype was shown to have a specific spatial distribution in the retina, which is potentially associated with changes in spectral radiance across different lines of sight. These results suggest that there have been strong selection pressures for G. australis to maintain broad spectral sensitivity for the brightly lit surface waters that this species inhabits during its marine phase. These findings provide important insights into the functional anatomy of the early vertebrate retina and the selection pressures that may have led to the evolution of complex color vision.

Not all estuaries are equally susceptible to anthropogenic perturbation. Microtidal estuaries with long residence times are intrinsically less robust than well-flushed macrotidal estuaries, facilitating the accumulation of contaminants. This promotes development of blooms of non-toxic and toxic phytoplankton, and hypoxia and anoxia may occur in deeper sections of the typically stratified water column. In Mediterranean and arid climates, high temperatures and low and/or seasonal rainfall can result in marked hypersalinity. Thus, any increase in anthropogenic perturbation will further decrease the health of a system in which the biota already experiences natural stress. Microtidal estuaries are also more susceptible to climate change, the detrimental longer-term effects of which are becoming manifestly obvious. Numerous attempts have been made to develop novel solutions to problems caused by eutrophication, phytoplankton blooms, hypoxia and hypersalinity, which have met with various levels of success, but the need for such measures and effective legislation is increasingly critical.

This study has employed an integrated statistical approach to determine the extents to which species richness and abundance (catch rate) of fishes over reefs along an extensive coastline were related to various factors. Fish were thus sampled by trapping over deep (~ 22 m) and shallow (~ 12 m) reefs along the ~ 1500 km tropical coast of north-western Australia (NWA). Fish were caught during day and night in both dry and wet seasons at two well-spaced locations in each of the Kimberley (13–16°S), Canning (16–19°S) and Pilbara (20–22°S) bioregions. Species richness and abundance were both typically less at the two locations at the lowest latitude than at the two at the highest latitudes. This trend, which contrasts with the paradigm regarding latitudinal trends for these biotic variables, is attributable to the far more extreme hydrological conditions in the Kimberley than Pilbara. Indeed, both biotic variables peaked in the Canning, presumably reflecting, inter alia, the better development of reef and suspension feeder habitats in that bioregion. The peak in abundance was attributable to particularly high numbers of the NWA endemic Lethrinus punctulatus. A greater species richness and abundance of fishes in deeper than shallow water during the wet season, and particularly in areas of greater cyclonic activity, reflect the movement of species such as Lethrinus laticaudis and Lutjanus carponotatus from shallow to calmer, deeper waters. These two biotic variables were greater during the day than night, with a greater number and abundance of diurnally-active species, e.g. lethrinids, feeding overall in the traps than is the case with nocturnal species, e.g. lutjanids. The results imply that the typical poleward latitudinal gradients in species richness and abundance are over-ridden along the NWA coast by environmental differences among bioregions.

The aim of this study was to determine the factors that influence the breaching of the bar at the mouth of estuaries that are normally-closed to the ocean and the trends exhibited by salinity and oxygen concentration in those systems during protracted periods of closure. Collated data for 1972 to 2016 demonstrate that the frequency and timing of bar breaching of three normally-closed estuaries, located along ~100 km of coastline in a low rainfall region of temperate south-western Australia, differ markedly. Breaching occurred in 12 years in Stokes Inlet, ≥ eight in Hamersley Inlet and only three in Culham Inlet. Breaching in each estuary was related to relatively very high volumes of fluvial discharge. Although breaching typically occurred following exceptional winter rainfall in Stokes Inlet, whose catchment received by far the greatest winter rainfall, it usually took place in Hamersley and Culham inlets following atypically high summer and autumn rainfall, often associated with cyclonic activity. Salinity, oxygen concentration and water temperature were measured seasonally between summer 2002 and spring 2004, during which period each of these estuaries was closed to the ocean following major natural breaches of each system and the influx of substantial volumes of oceanic water. Mean salinities in the estuary basins rose by markedly different extents during the three years of closure. They thus increased from 30 in Stokes Inlet, 35 in Hamersley Inlet and 52 in Culham Inlet, to maxima of 64, 143 and 293, respectively, with the highest individual salinity of 313 in the latter estuary the greatest yet recorded for any estuary worldwide. In contrast, oxygen concentrations declined to minima of 5.5, 2.5 and 0.6 mg L−1, respectively, and were inversely related to salinity in the basin of each estuary (r = −0.7 to −0.8). Although salinities in the main river of each estuary did not become as highly elevated as in its basin, they still reached 221 in that of Culham Inlet. The very different extents to which salinity increased and oxygen concentration declined among the three estuaries reflect variations in amount of rainfall and thus fluvial discharge, the area and depth of basin relative to discharge and resilience of the bar at the estuary mouth. Thus, while a suite of factors contribute to bar breaching and the physico-chemical characterstcs of normally-closed estuaries, variations in their importance as ‘drivers’ among estuaries should be considered when studying the ecology of a given system.

A 26-year time series of monthly samples from the water intake of a power station has been used to analyse the trends exhibited by number of species, total abundance, and composition of the mysids and caridean decapods in the inner Bristol Channel. During this period, annual water temperatures, salinities and the North Atlantic Oscillation Index (NAOI) in winter did not change significantly, whereas annual NAOI declined. Annual mean monthly values for the number of species and total abundance both increased over the 26 years, but these changes were not correlated with any of the measured physico-chemical/climatic factors. As previous studies demonstrated that, during a similar period, metal concentrations in the Severn Estuary and Bristol Channel (into which that estuary discharges) declined and water quality increased, it is proposed that the above changes are due to an improved environment. The fauna was dominated by the mysids Mesopodopsis slabberi and Schistomysis spiritus, which collectively contributed 94% to total abundance. Both species, which were represented by juveniles, males, non-brooding females and brooding females, underwent statistically-indistinguishable patterns of change in abundance over the 26 years. When analysis was based on the abundances of the various species, the overall species composition differed significantly among years and changed serially with year. When abundances were converted to percentage compositions, this pattern of seriation broke down, demonstrating that changes in abundance and not percentage composition were responsible for the seriation. As with the number and abundance of species, changes in composition over the 26 years were not related to any of the physico-chemical/climatic factors tested. Species composition changed monthly in a pronounced cyclical manner throughout the year, due to statistically different time-staggered changes in the abundance of each species. This cyclicity was related most strongly to salinity.

Contemporary multivariate statistics were used to test the hypotheses that the dietary compositions of three populations of labrids on the west Australian coast are related to body size and undergo seasonal changes and to elucidate the relative extents and basis for any dietary differences within and between those populations. Gut content analyses determined the dietary compositions of Choerodon rubescens in marine waters of the outer reefs in the World Heritage Area of Shark Bay (26° S; 114° E) and of Choerodon schoenleinii in inner protected reefs of that large embayment. The dietary compositions of C. rubescens and C. schoenleinii differed significantly among length classes, progressed serially with increasing body size, both overall and almost invariably in each season and were more closely related to body size than season, whose effect was at best minimal. The size‐related dietary change in C. rubescens involved, in particular, a shift from crustaceans and non‐mytilid bivalves to mytilid bivalves and echinoid echinoderms. Although the diet of C. schoenleinii followed similar size‐related changes, it contained a greater volume of gastropods when the fish were small and mytilids when large and only a small volume of echinoids. The dietary composition of C. rubescens in the Abrolhos Islands, 300 km to the south of Shark Bay, was related both to length class and season and differed from that of this labrid in Shark Bay with the ingestion of lesser volumes of mytilids and greater volumes of echinoids. The size‐related changes in diet imply that these species shift from foraging over soft substrata to over reefs as their very well‐developed jaws become sufficiently strong to remove attached and larger prey. The dietary compositions of C. rubescens and C. schoenleinii in Shark Bay and of C. rubescens at the Abrolhos Islands were related far more to habitat–locational differences than to length class and season. The above intraspecific and interspecific differences in diet are consistent with qualitative accounts of the relative abundances of the main prey in their respective environments, supporting the view that, despite specializations in their feeding apparatus, these labrids can feed opportunistically to a certain extent and could thus potentially respond to moderate changes in the composition of their prey caused by climate change and other anthropogenic effects.

This study determined how productivity measures for a fish species in different water depths of an estuary changed in response to the increase in hypoxia in deep waters, which had previously been shown to occur between 1993–95 and 2007–11. Annual data on length and age compositions, body mass, growth, abundance, biomass, production and production to biomass ratio (P/B) were thus determined for the estuarine-resident Acanthopagrus butcheri in nearshore shallow (

The species composition of fish communities in 15 microtidal estuaries in south-western Australia, ranging from permanently-open to normally-closed, is shown to be related to the geomorphological and hydrological regimes and not to environmental condition. This study then explored the effectiveness of using qualitative taxonomic distinctness and ABC curves for fish data as indicators of the environmental condition in nearshore, shallow waters of these estuaries and, in the case of taxonomic distinctness, also of their offshore, deeper waters. Neither of these indices require spatial or temporal reference data, which may be either prohibitively expensive and time-consuming to collect or unavailable. Taxonomic distinctness, in both nearshore and offshore waters, varied consistently among estuaries in relation to their recorded environmental status, and is thus a good indicator of overall estuarine condition. ABC analyses, however, did not prove a good measure of the environmental condition of the estuaries, because their results largely reflect differences in accessibility of the estuary to marine estuarine-opportunist species and especially those that grow to a larger size. It is concluded that taxonomic distinctness indices provide a rapid and cost-effective method for assessing the environmental condition of estuaries, particularly those with limited spatial or temporal reference data.

This review provides a composite account of the biological characteristics of the temperate gonochoristic species of the Platycephalidae. Initially, data were obtained for the five abundant platycephalid species in south-western Australia, which each came from either over bare substrata or seagrass and from either estuaries, marine coastal waters or marine embayments. The von Bertalanffy growth curves for females and males of each species differed significantly, with females having a greater TL∞ and lower growth coefficient k. From tests using their upper deciles, the total length (TL) attained by the largest females of each species was significantly greater than that of their males, whereas such a trend did not occur with age. The ratio of females to males in each abundant age class, and overall, exceeded parity for four of the five species (typically P < 0.001) and increased with increasing TL. Mortality estimates, which were similar for each sex of each species, suggest that Platycephalus speculator has been substantially exploited in a seasonally-closed estuary in which it completes its whole life cycle. The above and other biological data for the five species were collated with those published previously for two of those species and five other platycephalid species in south-eastern Australia and one in Japan and another in the Suez Canal, yielding the following conclusions for gonochoristic species of the Platycephalidae. Females attain a larger size than males, the extent varying markedly among species, whereas the longevities of the two sexes of each platycephalid species are similar. The maximum TLs and ages of the various species range widely, with values for females, for example, extending from 221 mm for Ambiserrula jugosa to 985 mm for Platycephalus fuscus and from four years for A. jugosa to 26 years for Platycephalus conatus. The overall ratio of females to males is positively related to the extent to which both the maximum TLs and TL∞s of the females exceed those of males. The above trends imply that growth, rather than differences in longevity and/or mortality, is the main factor contributing to the marked differences in sex ratios, which ranged widely from parity to 3.2:1. As the length at maturity, but not typically age at maturity, was greater for females than males, maturity is also related mainly to growth. The spawning periods of the various species overlapped, commencing as early as late winter/early spring, as temperatures started rising with four species and later in late spring/early summer with the three species found in estuaries, which would be advantageous as spawning in estuaries would occur when environmental conditions are most favourable for spawning success and larval retention.

Curves describing the length–otolith size relationships for juveniles and adults of six fish species with widely differing biological characteristics were fitted simultaneously to fish length and otolith size at age, assuming that deviations from those curves are correlated rather than independent. The trajectories of the somatic and otolith growth curves throughout life, which reflect changing ratios of somatic to otolith growth rates, varied markedly among species and resulted in differing trends in the relationships formed between fish and otolith size. Correlations between deviations from predicted values were always positive. Dependence of length on otolith growth rate (i.e., “growth effect”) and “correlated errors in variables” introduce bias into parameter estimates obtained from regressions describing the allometric relationships between fish lengths and otolith sizes. The approach taken in this study to describe somatic and otolith growth accounted for both of these effects and that of age to produce more reliable determinations of the length–otolith size relationships used for back-calculation and assumed when drawing inferences from sclerochronological studies.

The aim of this study was to determine the dietary characteristics and mouth morphology of Othos dentex and to use these data, together with in situ observations of feeding behaviour, to elucidate how foraging and diet are optimized by this piscivorous serranid. Seasonal spear and line fishing over reefs in south-western Australia yielded 426 O. dentex (total length, LT, 183-605mm), among which the stomachs of 95 contained food. The food in the stomachs of 76 fish was sufficiently undigested to be seen to contain, almost invariably, a single fish prey, which was typically identifiable to family and often to species. The prey of O. dentex, which were measured (LT), represented 10 families, of which the Labridae and Pempheridae constituted nearly two-thirds of the prey volume. Two-way crossed analysis of similarities of volumetric data for stomach contents showed that the dietary compositions of the different length classes of O. dentex in the various seasons were significantly related to length class of prey, but not to prey family, length class within the various prey families or season. Furthermore, an inverse (Q-mode) analysis, including one-way analysis of similarities, showed that the patterns in the prey consumed by the different length classes of O. dentex in the various seasons were related more strongly to length class than prey family. The former trend is exemplified in a shade plot, by a marked diagonality of the length classes of prey with increasing predator size. The ingestion of typically a single teleost prey, whose body size increases as that of O. dentex increases, reduces the frequency required for seeking prey, thus saving energy and reducing the potential for intraspecific competition for food. The ability of O. dentex to ingest large prey is facilitated by its possession of a very large gape, prominent recurved teeth, dorsal and independently-moveable eyes, cryptic colouration and effective ambush behaviour. Othos dentex has thus evolved very cost-effective mechanisms for optimizing its foraging and diet.

The Ukrainian brook lamprey Eudontomyzon mariae is the most widespread lamprey species in eastern Europe. Although E. mariae is generally considered a derivative of Eudontomyzon danfordi, an exclusively freshwater parasitic species, it has alternatively been suggested that it was recently derived from a now extinct anadromous Black Sea ancestor. Several non-parasitic lampreys and the landlocked sea lamprey, which have recently evolved from anadromous ancestors, still develop a seawater-type mitochondria-rich cell (SW-MRC) in their gills. In contrast, this cell type is not present in the gills of either Lampetra aepyptera, a non-parasitic lamprey of ancient origin, or the parasitic Ichthyomyzon unicuspis and I. castaneus that likewise have long evolutionary histories in fresh water. Eudontomyzon mariae from the Vistula River in the Baltic River basin does not possess SW-MRC, which is inconsistent with a recent origin from an anadromous ancestor. Mitochondrial DNA sequence data were thus used to infer the relationship between different populations of E. mariae and E. danfordi, and to reconstruct the transition from anadromy to freshwater residency. The results suggest that E. mariae evolved independently in the Baltic, Black, and Caspian Sea basins, and not recently from an anadromous ancestor. Although E. mariae in the Danube River may have arisen relatively recently from E. danfordi (differing by 0.7–1.1% in cytochrome b gene sequence), other E. mariae populations (including in the Vistula River) are genetically closer (0.6%) to the hypothetical ancestor of both E. mariae and E. danfordi. That ancestor was probably a freshwater resident, since SW-MRCs are not rapidly lost following confinement in fresh water.

This study has determined how the characteristics of the ichthyofauna of a large eutrophic microtidal estuary changed, initially in response to major structural remedial modifications, and then, during later years, as the environment became further modified, due mainly to effects of climate change. Data on the ichthyofauna of the Peel-Harvey Estuary, in south-western Australia, were derived firstly by seining seasonally in five regions over two consecutive twelve months (two years) in 2008–10. These data were then collated with those recorded previously using the same sampling regime throughout 1980 and 1981, when massive macroalgal growths were present, and throughout 1996 and 1997, soon after the opening, in 1994, of an artificial, deep and second entrance channel. The latter resulted in greater tidal flushing, consistently high salinities and reduced macroalgal biomass. Ichthyofaunal composition changed significantly overall and in four of the five regions across the three periods. Although increased tidal exchange did not lead to a rise in the number either of those marine species that typically use estuaries as nursery areas (marine estuarine-opportunists) or of those that complete their life cycle within the estuary (estuarine residents), the contributions made by the abundances of the representatives of those two groups to the total catch of fish varied markedly between periods. Those differences were largely responsible for the inter-period changes in species composition. In contrast to the situation with marine estuarine-opportunists, increased tidal exchange and higher salinities resulted in a greater number of marine straggler species entering the system, albeit in low numbers. The ichthyofauna during 1980–81 contained relatively large numbers of species that are typically associated with macrophytes, including marine estuarine-opportunists, e.g. Pelates octolineatus, and estuarine residents e.g. Ostorhinchus rueppellii and Hyporhamphus regularis. Following the opening of the artificial entrance channel, the relative abundances of these three macrophyte-associated species declined, whereas those of species, e.g. the marine estuarine-opportunist Torquigener pleurogramma and estuarine resident Favonigobius lateralis, which typically occur over unvegetated areas and in elevated salinities, increased. By 2008–10, such species had become more abundant, following declines in freshwater discharge and a longer persistence of high salinities, with macrophyte-associated species, e.g. the marine estuarine-opportunists P. octolineatus, Gymnapistes marmoratus and Haletta semifasciata and estuarine resident O. rueppellii, becoming more numerous as macroalgal and seagrass areas became better developed. This study demonstrates the great value of long-term data sets for detecting and predicting the effects of major structural changes and climate change on the faunas of estuaries.

Estuaries, lagoons, and marine embayments that become hypersaline (salinity > 40) are found around the world, but are most common in tropical, arid, and warm temperate climates with low and/or highly seasonal rainfall. The area of these systems range markedly from 10,000 km2, but are generally shallow ( 100, which can result in mass mortalities of flora and fauna and a simplification of the biotic community and food web. Climate change over the coming decades will potentially influence the extent of hypersalinity in estuaries and lagoons, by altering the frequency and magnitude of rainfall and the sea-level height. Changes in rainfall and sea level will also influence the extent of connectivity with the ocean.

Despite their highly conserved body plan and larval stage, adult life history type in lampreys diverges on two main axes related to migration and feeding. Of the 41–45 recognized lamprey species, 18 species feed parasitically after metamorphosis and their juvenile (sexually immature) feeding phase lasts from 3–4 months to 2–4 years. Nine of these species are exclusively freshwater resident; five are exclusively or almost exclusively anadromous, and four (sea lamprey, European river lamprey, Arctic lamprey, and, to a lesser extent, Pacific lamprey) are largely anadromous but with established freshwater populations. The other 23–27 described species are non-parasitic “brook” lampreys which remain within their natal streams. They initiate sexual maturation during metamorphosis, and, because the non-trophic periods of metamorphosis and sexual maturation are superimposed, the parasitic feeding phase is eliminated; this makes them the only vertebrates known to have non-trophic adults. Body size at maturity varies dramatically among life history types, ranging from ~110 to 150 mm total length (TL) in non-parasitic species to 800–900 mm TL in the anadromous sea lamprey. Freshwater forms are typically intermediate in size, although those that inhabit small systems may be no larger than non-parasitic lampreys and others (particularly the Great Lakes sea lamprey) are quite large. Some anadromous species (most notably European river lamprey, Pacific lamprey, and Arctic lamprey) show considerable intraspecific variation, consisting of typical large-bodied forms and dwarf or “praecox” forms that appear to feed at sea for a reduced period of time. Establishment in fresh water is more common in species that are consistently small-bodied or those with praecox forms. The only exceptions are the very small-bodied western river lamprey (mean TL at maturity ~200 mm), which does not produce freshwater parasitic forms (although it has given rise to innumerable non-parasitic freshwater populations), and the sea lamprey which, despite its very large size, has successfully colonized the Great Lakes. Abundant prey of a suitable size range is critical for establishment of freshwater parasitic populations. However, even with abundant prey, abandonment of anadromy is expected only under circumstances where decreases in mortality and the costs associated with migration make the reduction in size at maturity, and the accompanying reduction in fecundity, worthwhile. Pacific lamprey generally fail to establish when isolated above recently constructed barriers, likely because the reservoirs in which they have been isolated are relatively small and because they appear to osmoregulate poorly in fresh water. However, because colonization of fresh water appears to select for individuals “pre-adapted” to feed and grow to maturity in fresh water (i.e., relying on existing genetic variation within the source population), probability of establishment would likely increase with the number of founders. The existence of three closely related freshwater parasitic species suggests that Pacific lamprey successfully colonized fresh water in the past. Whether sea lamprey colonized Lake Ontario and Lake Champlain post-glacially or in historic times is debated. At present, the “invasion-by-canal” hypothesis appears to be the most convincing, but definitive resolution should be possible with genome-level analyses. Given the decimation of the Great Lakes ecosystem by sea lamprey, it is critical to be able to predict the potential for anadromous lampreys to become invasive in other freshwater systems. Migratory type is rarely considered a species-specific character unless it is accompanied by identifiable morphological differences. In contrast, variability in feeding type has long been considered a species-specific character because size-assortative mating was thought to result in reproductive isolation between parasitic and non-parasitic forms. However, not all parasitic and non-parasitic forms appear to be reproductively isolated, and different species show different degrees of divergence from their presumed parasitic ancestor. “Paired” non-parasitic species are defined as those that are morphologically similar to a particular parasitic species in all aspects other than body size, and “relict” brook lampreys are those that cannot be obviously paired with extant parasitic forms. However, molecular analyses have: (1) identified the closest extant parasitic relative to these relict species (although a few “orphan” species still remain, where identification of the closest living relative still sheds little light on the identity of the parasitic ancestor); (2) shown that the distinction between paired and relict species is sometimes unclear; and (3) demonstrated that there is also considerable variation among paired species in the degree to which they are morphologically and genetically differentiated from their parasitic ancestors. We review this “speciation continuum,” particularly in European river and brook lamprey populations where recent genetic and genomic studies show significant gene flow between these species where they co-occur (i.e., refuting assumptions of complete reproductive isolation resulting from size-assortative mating) while also showing that there are genome-level differences between the feeding types (i.e., refuting the hypothesis of phenotypic plasticity). In sympatry, European river and brook lampreys appear to be partially reproductively isolated ecotypes that nevertheless maintain distinct phenotypes, because regions of the genome involved in reproductive isolation and local adaptation resist the homogenizing effect of introgression. Interestingly, the results of analyses used to reconstruct the demographic history of divergence in this species pair are inconsistent with recent and rapid divergence in sympatry following the recent glacial retreat; rather, they support divergence in allopatry ~200,000–250,000 years ago and re-establishment of secondary contact ~90,000 years ago. Some loci have been identified that differ between the forms (e.g., the vasotocin and gonadotrophin-releasing hormone 2 precursor genes), but an understanding of the genetic basis of life history evolution in lampreys remains elusive. There appear to be strong parallels between factors that promote or constrain loss of anadromy in parasitic species (and reduction in duration of the feeding phase) and those that lead to or limit the evolution of non-parasitism (i.e., total elimination of the feeding phase). Smaller-bodied parasitic species have been far more prolific in producing non-parasitic derivatives than others; western river lamprey are already so small at maturity that “skipping” right to a non-parasitic form represents a more profitable trade-off between mortality and fecundity than freshwater parasitism. In contrast, there is a conspicuous absence of brook lamprey derivatives from the large-bodied sea, pouched, and Caspian lampreys. Our comparisons suggest that 300 mm TL (with a 10–12× reduction in fecundity) is the cut-off above which shifts to non-parasitism would not be beneficial. Therefore, we predict that Great Lakes sea lamprey is not an “intermediate” freshwater parasitic form that will give rise to a non-parasitic derivative, because complete elimination of the parasitic feeding phase would represent too large (~40×) a reduction in fecundity.

Mesozooplankton was sampled seasonally in a large microtidal estuary (Peel-Harvey) suffering from massive macroalgal growths and cyanobacterial blooms. Comparisons with other estuaries indicate that eutrophication led to copepod abundance declining and macroalgal-associated species increasing. Mesozooplankton species are almost exclusively autochthonous, i.e. spend entire life cycle within the estuary. Meroplanktonic species are virtually absent because main benthic macroinvertebrate species undergo direct benthic rather than planktotrophic development. There are also few abundant holoplanktonic species. Most species are tychoplanktonic, i.e. benthic and transported into plankton through physical disturbance of sediment. Species number, concentration and Simpson's Index are greater during night than day. Annual cyclical changes in species composition are related closely to changes in salinity. At the most degraded site, nematode concentrations were high and the species number and concentration changed markedly during extreme eutrophication, when oxygen concentrations were low, disrupting annual cyclical changes in species composition.

This study has elucidated the environmental factors associated with spawning and the ecology of early life cycle stages of the sparid Acanthopagrus butcheri, which is atypically long-lived and large for a species confined to its natal estuary. The prevalence of A. butcheri eggs in monthly plankton samples from the Blackwood River Estuary, south-western Australia, in 2014/15, allied with long-term gonadal data, imply that spawning in this estuary commences in mid-spring (October) as water temperatures increase to ~17 °C and peak at ~22 °C in early summer (December). Eggs were initially found only in deeper, downstream areas, where a salt wedge had started to penetrate following precipitous seasonal decline in freshwater discharge. Spawning occurred progressively further upstream during November/December as the salt wedge continued its intrusion of the upper estuary. The concentrations of eggs and yolk-sac and preflexion larvae, which were related positively to salinity and temperature and less so to oxygen concentration, were located predominantly below the halocline, implying that successful spawning typically requires salinities ≥15. Concentrations of eggs and yolk-sac and preflexion larvae peaked in December and of flexion larvae in January. As the concentrations of copepod nauplii exceeded by orders of magnitude those of larval A. butcheri, with which they co-occur and constitute their main prey, it is unlikely that restricted food resources accounted for the poor recruitment of the 2014/15 year class. In this context, the presence of many yolk-sac larvae and preflexion larvae in the low oxygen concentrations, which have become increasingly prevalent in microtidal estuaries of south-western Australia due to climate change, is likely to have led to considerable mortality. In most populations throughout its range in southern Australia, A. butcheri spawns in a restricted period between the austral mid-spring and mid-summer, with the synchrony achieved through differences in the temperatures that cue spawning at different latitudes, i.e. higher temperature cues at lower and thus warmer latitudes. Spawning occurs earlier, however, in atypical estuaries in which salinities and temperatures are high in late winter/spring. Despite experiencing episodic recruitment, A. butcheri sustains substantial populations through maturing early relative to its maximum age, and therefore producing numerous offspring in those few years when spawning conditions are optimal. Episodic recruitment could thus be related to subtle inter-annual differences in environmental conditions during the short spawning periods, with oxygen levels greater than usual a potential key factor. The adaptability of A. butcheri makes this sparid useful in assessing the degree, direction and scale of climate change effects.

Chrysophrys auratus was collected from one sub-tropical and two temperate regions spanning >2400 km along the coast of Western Australia (∼23.5–35.5° S). Marginal increment analysis demonstrated that, while a single opaque zone is formed in the otoliths of C. auratus each year, the period of deposition varies among regions. An opaque zone was formed in May to early September in the sub-tropical upper west coast, and thus when water temperatures were declining to their minima. In contrast, opaque zone formation occurred 3 months later in August to December in the temperate lower west and south coasts, when water temperatures were rising from their minima. The length and age distributions differed markedly among populations of C. auratus, with the strongest year classes varying among the three regions. Thus, it is likely that year class strength of C. auratus throughout its distribution along the coast of Western Australian is mostly related to local environmental conditions. Chrysophrys auratus grew far less rapidly and attained a smaller size in the warmer upper west coast than in the cooler temperate regions of the lower west and south coasts. A collation of data on C. auratus from ten populations in Australia and three in New Zealand showed that growth is greatest towards the mid-latitudes of its geographic range, i.e. at ∼31° S. Estimates of mean lengths at specified ages thus exhibit a parabolic relationship with latitude, with reduced growth (i.e. edge-of-range effects) occurring towards the latitudinal margins of the distribution of this sparid.

Biological characteristics of Pentaceropsis recurvirostris, Paristiopterus gallipavo and Parazanclistius hutchinsi were determined from commercial gillnet samples from temperate south-western Australian coastal waters. Growth zones in otoliths, with more than a few such zones, were readily detectable only after the otoliths had been sectioned. Visual analyses and modelling of the trends in marginal increments on sectioned otoliths demonstrate that these opaque zones are formed annually. Maximum ages of 55, 36 and 49 years, derived for P. recurvirostris, P. gallipavo and P. hutchinsi, respectively, reflect relatively low mortalities. These longevities greatly exceed those estimated, using otoliths, for Pentaceros wheeleri and Pentaceros richardsoni, which belong to the other pentacerotid subfamily. These differences may be due to the counts of ‘daily’ growth zones in sectioned otoliths of P. wheeleri not representing the complete age range of that species and the zones detected in whole otoliths of P. richardsoni not constituting the complete range of annually-formed zones. Pentaceropsis recurvirostris, P. gallipavo and P. hutchinsi recruited into the fishery in the sampling area as 2–3 year-old fishes. Pentaceropsis recurvirostris and P. hutchinsi exhibited little or no subsequent growth throughout the remainder of their protracted life, whereas, P. gallipavo continued to grow for c. 5 years and then underwent little further growth. Spawning of P. recurvirostris and P. hutchinsi peaked in the austral winter and autumn, respectively, but in the austral spring and summer with P. gallipavo, which is more typical of temperate species. Although the females of P. gallipavo and P. hutchinsi were mature, this did not apply to a few P. recurvirostris, some of which were >20 years old, implying that any given female of this species does not always spawn every year. Ovarian mass greatly exceeded testis mass, indicative of pair spawning, which is consistent with field observations. In contrast to P. recurvirostris and P. hutchinsi, the sex ratio was heavily biased towards males and the spawning period longer in P. gallipavo, suggesting that selection pressures for spawning success were greater for this latter species.

The overall growth of Acanthopagrus butcheri in the eutrophic Swan River Estuary has previously been shown to decline between 1993–95 and 2007–11. This was attributed to the effects of an increase in hypoxia on A. butcheri in deeper water, brought about by reductions in freshwater flushing, and to density-dependent effects as this species became concentrated in the better-oxygenated, nearshore shallow waters. In the present study, a year-effect model was developed that provided a good fit to the lengths at age and could thus be used to explore the following: 1) The extent to which somatic growth of A. butcheri differed between years in the above two periods and within the later period, which was extended to include data for 2012 to 2014, and 2) whether annual growth in 2007–14 was related to temperature and/or freshwater discharge. Annual length increments for females and males during the second year of life, predicted from the model and when using a common initial length, were almost invariably less in each year in 2007–14 than in 1993–95. In 2007–14, these predicted increments varied by ∼2 times for both females and males and were positively correlated with average temperature during the main growth phase of A. butcheri . They were not significantly correlated, however, with freshwater discharge in the preceding cool wet ‘winter’ months, when the vast majority of rainfall occurs. The demonstration that the growth of A. butcheri was positively correlated with temperature for years in the latter period is consistent with the metabolic theory of ecology and contrasts with growth declining between 1993–95 and 2007–14 when temperatures were increasing. Thus, any influence of temperature on growth between those periods was overridden by the effects of other factors, i.e. hypoxia and related changes in density. As A. butcheri completes its life cycle within its natal estuary and has plastic biological characteristics, it is an ideal candidate for use as an indicator of the health of an estuary and for hypothesising on the effects of climate change on fish species.

Population connectivity has profound ecological and evolutionary implications. In marine species with complex life cycles, the nature of these implications depends on both the amount of dispersal and the life-cycle stage(s) through which dispersal occurs. For demersal fishes with such life cycles, the pelagic early life stages (ELS) are generally considered the main dispersive phase, though this assumption has rarely been tested. This research investigates genetic connectivity in the reef-dwelling labrid Choerodon rubescens, which is a prized eating fish endemic to ca 1200km of the west coast of Australia. This species has demersal juveniles and adults, and pelagic ELS that are predicted to last about 25-30days. The aim of the study was to use patterns of variation at 12 microsatellite loci to test the hypothesis that C. rubescens is genetically homogeneous across its main distribution. The genetic analyses were based on samples of 26-40 individuals from six locations, which collectively span all of the areas where C. rubescens is common. The values of global FST (0.0019) and DEST (0.0010) were not significantly different from zero and Bayesian clustering indicated that all individuals belonged to a single genetic group. In addition, Mantel tests showed no evidence of isolation by distance. These results support the view that C. rubescens is genetically homogeneous over all or most of its geographic range. Since published otolith microchemistry evidence indicates that the juveniles and adults of C. rubescens are relatively sedentary, these results also imply that the pelagic ELS are the main avenue of dispersal in this species. This study highlights the value of combining the results of complementary methods for assessing the relative importance of the different life-cycle stages in dispersing a fish species. The results also have implications for the management of C. rubescens, which has shown signs of localised overfishing. Specifically, the dispersal of the ELS provides a mechanism for the recruitment of C. rubescens to non-natal reefs. Such connectivity could help this species to recover from localised depletions in abundance and ameliorate the potential evolutionary consequences of any localised overfishing, such as reductions in genetic diversity or selective responses to harvesting.

Long-term monitoring data and models have been used to explore the efficacy of restocking an estuarine-resident teleost species. Juveniles of Acanthopagrus butcheri were cultured from broodstock from the Blackwood River Estuary in 2002 and their otoliths stained with alizarin complexone. 150,000 marked juveniles were released into the Blackwood River Estuary at three months old in early 2003, with the stain in their otoliths subsequently remaining visible during the following 16 years. Samples of A. butcheri were obtained annually from a commercial gill net fisher and at intervals by fishery-independent methods. Commercial catch per unit effort was positively related to freshwater discharge. Indices of year class strength, derived from annual age-frequency distributions and assuming length-dependent natural mortality, demonstrate that between 1993 and 2012, natural recruitment to the population was only strong in 1999 and 2008 and was not significantly related to freshwater flow. The number of wild stock A. butcheri ≥ minimum legal length (250 mm total length), comprising mainly the 1999 year class, were estimated to have declined sequentially to only ∼12,000 fish in 2010. The restocked fish contributed between 61 and 73 % to the total number of fish in the commercial catches between 2007 and 2010 and their numbers remained at > 10 % of their number at release until 2011. The contribution of the 2008 year class, of which ∼50 % had been estimated as derived from restocked fish, increased from 20 % of the commercial catch in 2012 to between 50 and 80 % between 2013 and 2018. A progressive decline in growth of year-class groups of wild stock fish, from 1970-1998 to 2008-2011, is considered to reflect the detrimental effects of hypoxia. Restocked fish grew less rapidly than younger and older year-class groups of wild stock fish, suggesting that the growth of cultured fish may have been compromised by hatchery processes. The large contributions made by restocked fish to commercial catches over several years and to future generations highlight the efficacy of restocking for replenishing and sustaining a depleted population of an estuarine-resident species.

This study describes the ecology of mesozooplankton in the shallows of the large central basin area of the Swan-Canning Estuary on the microtidal lower west coast of Australia during the mid-1980s when, as in most other south-western Australian estuaries, it was mesotrophic. As the vast majority of species reproduce within the estuary and there is a lack of a net upstream flow of bottom water during each tidal cycle to facilitate selective tidal transport, the populations of those species are considered autochthonous. Species restricted to the estuary accounted for 63% of the total number of species and 83% of abundance. Contributions by tychoplankton to total number of species (68%) and individuals (59%) exceeded the corresponding values of 18 and 39% for holoplankton and 14 and 2% for meroplankton. Low meroplankton values result from a paucity of benthic macroinvertebrate species with planktotrophic development. Comparisons with data for the shallow basin areas of the nearby highly eutrophic Peel-Harvey Estuary were used to indicate how mesozooplankton in the microtidal estuaries respond to excessive nutrient enrichment. The mean number of species in the Swan-Canning was essentially the same as in the Peel-Harvey, whereas concentrations were only half, reflecting the lower productivity of the former estuary. However, concentrations of the four most abundant species in the Swan-Canning, the amphipod Grandidierella propendatata, the calanoids Gladioferens imparipes and Acartia cf. clausi and a harpacticoid species, exceeded those of these species in the Peel-Harvey by between 1.6 and 11.7 times. Greater concentrations in the Swan-Canning were attributable to this mesotrophic system not undergoing the reduction in oxygen concentrations and/or environmental degradation, to which these species are susceptible. In contrast, concentrations of the amphipods Corophium minor and Tethygenia elanora and large nematodes, which are tolerant of degraded environmental conditions, were greater in the Peel-Harvey. Holoplankton made a far greater contribution in the Swan-Canning than Peel-Harvey, due to substantial numbers of copepods that benefit from good environmental conditions. Mesozooplankton composition in both estuaries underwent cyclical changes during the year due to time-staggered differences in seasonal concentrations of various species. Cyclical changes and variations in composition were more closely related to measured environmental variables in the Swan-Canning than Peel-Harvey estuaries. The concentrations of many species were greater at night than during the day presumably reflecting a nycthemeral response and/or low nocturnal oxygen concentrations at the bottom of the water column.

This study has determined the diet of the demersal Knifejaw Oplegnathus woodwardi in depths of 50–200 m off the southern coast of Western Australia, where the benthic invertebrate epifauna is overwhelmingly dominated by sponges. The many fused teeth that form the parrot-like beak of O. woodwardi are used in conjunction with strong muscular plate-like jaws to shear/chop off pieces of sponge and crush the spicule-containing skeleton. Despite the potentially formidable physical and chemical defences (siliceous spicules and secondary metabolites) of sponges, these invertebrates constitute the main prey of O. woodwardi. Sponges were thus ingested by 44% of O. woodwardi and contributed 38% to the volume of the stomach contents across a wide length range of fish. The volumetric contribution of sponges was, however, far less in the stomachs than intestines, whereas the reverse was true for teleosts. This is presumably due to sponges undergoing less digestion than the externally soft-bodied teleosts as food passes through the gut, which is consistent with the large numbers of mainly intact spicules present in the intestine. Since the poriferan prey consisted almost exclusively of species of the Tetractinellida, even though there are three other speciose sponge orders in the region where O. woodwardi feeds in southern Western Australia, this predator apparently selects the sponge taxa it ingests. The length of the siliceous spicules of the Tetractinellida often exceeds 2000 μm, a value nearly ten times that which acts as a deterrent in another fish predator-sponge interaction. Thus, despite possessing formidable defence mechanisms, tetractinellinids are palatable to O. woodwardi. The next most important prey after sponges was teleost fish (among which clupeids were relatively abundant), being ingested by 35% of individuals and comprising 28% of the stomach contents. Other major invertebrate prey comprised hard-bodied crustaceans (mainly decapod crabs), echinoderms, bivalves and cephalopods (with their hard beaks and internal shells), all of which were probably associated with the particular habitat occupied by tetractinellid sponges. These hard-bodied prey are processed by O. woodwardi through the crushing action of its strong jaw mechanism. It is beneficial for O. woodwardi to feed on tetractinellid sponges because they are sessile, palatable and very abundant in the environment of this predator and thus do not incur a high energetic cost of foraging.

The anadromous Geotria australis, one of only three lamprey species representing the early agnathan (jawless) stage of vertebrate evolution in Australia and New Zealand, is declining in abundance. Its adults were caught soon after they had entered rivers on their non-trophic upstream migration and maintained in laboratory tanks for 13–15 months through to spawning. As adult G. australis are susceptible to haemorrhagic septicaemia, they were treated prophylactically and maintained in 3-m3 aquaria supplied with a flow-through charcoal filtration system and UV steriliser. Air temperature and the light:dark regime were constantly adjusted to parallel those in the environment. Males developed the very large suctorial disc and gular pouch characteristic of maturity and both sexes matured at the same time as in the wild. While males frequently showed aggressive behaviour towards each other, the same male and female mated on several occasions. The male coiled around the female and, with his urogenital papilla close to the female’s cloaca, twisted and vibrated, leading to egg release. These eggs formed coagulated clusters as in the wild, with many progressing through to the eight-cell stage. Remarkably, numerous G. australis were still alive 95–392 days after the end of the short spawning period, and one male after a further 119 days. Postspawning survival would be facilitated inter alia by extensive proteolysis, reflected in a shortening of the body. The data in this paper emphasise that G. australis is a highly atypical lamprey and provides invaluable information for conserving this declining species.

Measurements have been made of those changes which lead to increases in the surface area of the intestine during the metamorphosis of three species of lampreys. Although the intestine of the Southern Hemisphere lamprey, Geotria australis, increases in length by 1.13 times and in diameter by 1.12 times, the main factor influencing the 5.71 times increase in surface area is the development of longitudinal folds. The contribution of the typhlosole to the internal perimeter of the intestine is less in most life cycle stages of G. australis than in Lampetra spp. The changes in the various intestinal measurements of the nonparasitic species L. planeri parallel those of the presumed ancestral parasitic species, L. fluviatilis, during the first six stages of metamorphosis. However, the longitudinal folds, but not the typhlosole, subsequently start regressing in L. planeri just after the time when the rate of gonadal development increases markedly. An account is also given of the pattern of fold formation and the development of the typhlosolar vein in G. australis.

This study demonstrates that the silver technique of Grimelius (Acta Soc. Med. Ups. 73:243–270, 68) is ideally suited for the study of cardiovascular chromaffin cells in lampreys. This method showed that in the Southern Hemisphere lamprey, Geotria australis, the distribution of chromaffin cells differs from that described for holarctic species. In G. australis, the chromaffin cells are found mainly in the sinus venosus, atrium, and nearby regions of the cardinal and jugular veins, and they are absent from the ventricle and conus arteriosus. The location and discreteness of the large accumulation of chromaffin cells in the lateral wall of the right posterior cardinal vein of adults resemble those of the precardiac axillary bodies of elasmobranchs. Chromaffin cells become more abundant during metamorphosis. The possible phylogenetic and functional significance of lamprey chromaffin cells is briefly discussed.

The morphology, cell types, and innervation of the several small papillae (x̄ = 17) and two larger papillae, which together form a ring just outside the fimbriae surrounding the suctorial disc of adult Geotria australis, have been studied using various histological stains, including silver impregnation, and scanning and transmission electron microscopy. The epithelium of all papillae consists almost entirely of mucigenic cells. The multivillous and oligovillous cells, which are found elsewhere in the lamprey epidermis, were not observed, and Merkel and polyvillous cells are rare. Free nerve endings are common, however, in the basal layers of the epidermis. Unlike the small papillae, the two large papillae contain a core of skeletal muscle and a prominent layer of dermal collagen. In the submucosa of these large papillae, the nerves form a dense, compact layer that contains many large and probably sensory axons. It is suggested that the oral disc papillae of adult G. australis are encapsulated mechanosensory structures that play a role in enabling the animal to locate and attach to a suitable point on host fishes or other surfaces.

This study has explored whether the restocked fish of a species, which is confined to an estuary, perform as well as its wild stock, and has estimated their contribution to the commercial fishery and egg production. The biological characteristics of the 2001 and 2002 year classes of Acanthopagrus butcheri, which had been cultured and introduced into the Blackwood River in south-western Australia at seven and four months old, respectively, were thus determined from samples collected regularly between 2002 and 2014. The restocked fish could always be distinguished from the wild stock because their otoliths retained the pink colouration of the alizarin complexone with which they had been stained prior to release. Detailed analyses demonstrated the growth and maturity schedules of restocked fish were only slightly inferior to those of the wild stock and the mean gonad weights of the females of these two groups did not differ significantly in any month. As increasing numbers of restocked A. butcheri attained the MLL of 250 mm for retention, their contribution to the commercial fishery increased from 6% in 2005 to 74% in 2010. That contribution subsequently declined to 39% in 2012 and 10% in 2014, due predominantly to the introduction of the very strong 2008 year class in the commercial catches, the first substantial recruitment into the population since 1999. Restocked fish were estimated as contributing ~55% to the eggs produced in 2008, suggesting that substantial numbers of the 2008 year class were derived from spawning by restocked fish. The results of this and a previous genetic study imply that restocking is an effective and appropriate way for replenishing stocks of an estuarine species such as A. butcheri, especially as its recruitment is highly episodic.

The timing and duration of spawning and maturation schedules of Chrysophrys auratus were determined for populations in one subtropical (∼25°S on the upper west coast) and two temperate regions (∼32°S on the lower west and ∼35°S on the south coasts) over >2000 km of coastline along the west coast of Australia. This study thus encompassed the wide latitudinal range of this recreationally and commercially important sparid in this region. The results were used, in conjunction with previously published data, to explore traditional paradigms regarding the relationships between the reproductive characteristics and variations in water temperature. Spawning at each latitude occurred mainly at 19–21°C, but following a decline in temperature in the subtropical region and after a rise in temperature in the two temperate regions. Spawning on the upper west coast thus occurred between mid-autumn and early spring (∼7 months) as opposed to late winter to early summer on the lower west coast (∼6 months). Spawning on the south coast was mainly restricted to mid-spring to early summer (∼2–3 months) in 2003 and 2004 and did not occur in 2005 when temperatures in this period were the coldest on record. Thus, marked interannual differences in the prevalence of mature fish on the south coast probably reflect the “marginality” of the population. The length (L50) and age (A50) at which C. auratus matured increased markedly from 25 to 32°S. Studies such as this allow for latitudinal variations in reproductive characteristics to be incorporated into population models to optimize fisheries sustainable yield, and contribute towards appropriate spatial scales for sustainable management strategies (e.g. minimum legal lengths consistent with latitudinal variation in length-based maturity schedules). The narrow temperature range over which this species spawns accounts for its current latitudinal distribution and enables predictions of how this distribution might alter with climate change. This study provides relevant information for management and climate change implications for similar subtropical and temperate marine teleosts.

A Study Tour is an opportunity for reflection in a new context. It emphasises experiential learning and offers both group and self-directed activities, enabling participants to explore new territories, cultures and people. It is a transformative reflectivce activity. This paper learns from the case study of a transformative experience for a group of Jamaican teachers and principals crossing the borders and engaging in a UK Study Tour. The evidence illuminates how teachers and principals might cross mental borders and widen their perspectives on the practice and leadership of education through experiential activities, and the ways teachers and principals can integrate new insights gained from crossing a border with existing knowledge from their side of their border. The main purpose of this qualitative reflective case study was to investigate the impact that Study Tours can have. The findings suggest that participants experienced remarkable personal and professional growth which are likely to result in significant changes to their practice and professional identity.

This study has determined the extents and basis for variations in the composition of the prey ingested by the abundant species of a family highly adapted for ambush predation, i.e. Platycephalidae, in a region (south-western Australia) where that family is found in different habitats and environments. Dietary data were thus collected for Leviprora inops and Platycephalus laevigatus from seagrass in marine embayments and for Platycephalus westraliae from over sand in an estuary. These were then collated with those recorded previously for Platycephalus speculator from over sand and in seagrass in an estuary and for Platycephalus longispinis from over sand in coastal marine waters. While crustaceans and teleosts together dominated the diet of all five species, their percentage volumetric dietary contributions varied greatly, with those of crustaceans ranging from 7% for L. inops to 65% for P. speculator and those of teleosts ranging from 29% for P. longispinis to 91% for L. inops. For analyses, the data were separated into two sets. The first comprised the 17 dietary categories of invertebrates and all identified and unidentified teleosts collectively, while the second consisted of the 23 identified teleost families, both of which were subjected to permutational analysis of variance (PERMANOVA), analysis of similarities (ANOSIM) and a new (two-way) version of the RELATE procedure. The diets of three species changed seasonally, when using invertebrate dietary categories and teleosts collectively, but with only one species, when employing identified teleost families, probably reflecting a greater tendency for invertebrate than teleost prey abundance to change during the year. On the basis of dietary data for invertebrate taxa + teleosts collectively, the diets of three of the five species changed serially with body size, with a fourth species feeding, throughout life, predominantly on the carid Palaemonetes australis. Based on identified teleost families, the diets of the three species that fed predominantly on teleosts underwent serial size-related changes. Although L. inops and the co-occurring P. laevigatus both consume large volumes of teleosts, the former ingests larger, less demersal and more mobile prey, e.g. the labrids Haletta semifasciata and Neoodax balteatus, than the latter, e.g. the scorpaenid Gymnapistes marmoratus, reflecting the possession by L. inops of a far longer head and larger buccal cavity. Circumstantial evidence suggests that the large differences in the volumes of crustaceans and teleosts consumed by each platycephalid species are related to differences in the relative availability of these prey in the different habitats or environments of each species.

Lampreys and hagfishes are the sole extant representatives of the early agnathan (jawless) vertebrates. We compared retinal function of fully-metamorphosed, immature Mordacia mordax (which are about to commence parasitic feeding) with those of sexually-mature individuals of its non-parasitic derivative M. praecox. We focused on elucidating the retinal adaptations to dim-light environments in these nocturnally-active lampreys, using electroretinography to determine the temporal resolution (flicker fusion frequency, FFF) and temporal contrast sensitivity (CS) of enucleated eyecups at different temperatures and light intensities. FFF was significantly affected by temperature and light intensity. Critical flicker fusion frequency (cFFF, the highest FFF recorded) of M. praecox and M. mordax increased from 15.1 and 21.8 Hz at 9°C to 31.1 and 36.9 Hz at 24°C, respectively. CS of both species increased by an order of magnitude between 9 and 24°C, but remained comparatively constant across all light intensities. Although FFF values for Mordacia spp. are relatively low, retinal responses showed a particularly high contrast sensitivity of 625 in M. praecox and 710 in M. mordax at 24°C. This suggests selective pressures favour low temporal resolution and high contrast sensitivity in both species, thereby enhancing the capture of photons and increasing sensitivity in their light-limited environments. FFF indicated all retinal photoreceptors exhibit the same temporal response. Although the slow response kinetics (i.e., low FFF) and saturation of the response at bright light intensities characterise the photoreceptors of both species as rod-like, it is unusual for such a photoreceptor to be functional under scotopic and photopic conditions.

Data on the fish fauna of the Leschenault Estuary on the lower west coast of Australia were collected and used as a model to elucidate the characteristics of permanently open estuaries with a reverse salinity gradient, which undergo seasonal changes similar to many other estuaries with Mediterranean climate. Focus was placed on determining (1) the relationships of the number of species, density, life cycle category and species composition of fishes with region (within estuary), season and year and salinity, (2) whether species are partitioned along the lengths of such systems and (3) the extent and significance of any inter-decadal changes in species composition. The analyses and interpretation involved using multi-factorial permutational multivariate analysis of variance (PERMANOVA) and analysis of similarity (ANOSIM) designs, and three new or recently published visualization tools, i.e. modified non-metric multidimensional scaling (nMDS) plots, coherent species curves and segmented bubble plots. The base, lower, upper and apex regions of the Leschenault Estuary, along which the salinity increased in each season except in winter when most rainfall occurs, were sampled seasonally for the 2 years between winter 2008 and autumn 2010. Estuarine residents contributed twice as many individuals, but less than half the number of species as marine taxa. While the numbers of marine species and estuarine residents declined between the base or lower and apex regions, the individuals of marine species dominated the catches in the base region and estuarine residents in the other three regions. Ichthyofaunal composition in each region underwent conspicuous annual cyclical changes, due to time-staggered differences in recruitment among species, and changed sequentially along the estuary, both paralleling salinity trends. Different groups of species characterized the fauna in the different regions and seasons, thereby partitioning resources among species. The ichthyofauna of the apex region, in which salinities reached 54 and temperatures 36° C, recorded the highest maximum density and, in terms of abundance, was dominated (90%) by three atherinid species, emphasizing the ability of this family to tolerate extreme conditions. Comparisons between the data for 2008-2010 and 1994 demonstrate that the spotted hardyhead Craterocephalus mugiloides and the common hardyhead Atherinomorus vaigiensis had colonized and become abundant in the Leschenault Estuary in the intervening period. This represents a southwards extension of the distribution of these essentially tropical species during a period of increasing coastal water temperatures as a result of climate change. The abundance of weed-associated species, e.g. the western gobbleguts Ostorhinchus rueppellii and the soldier Gymnapistes marmoratus, increased, whereas that of the longfinned goby Favonigobius lateralis decreased, probably reflecting increases in eutrophication and siltation, respectively.

As Acanthopagrus butcheri typically completes its life within its natal estuary and possesses plastic biological characteristics, it provides an excellent model for exploring the ways and extent to which a fish species can respond to environmental changes over time. The environment of the Swan River Estuary in south-western Australia has deteriorated markedly during the last two decades, reflecting the effects of increasing eutrophication and hypoxia in the upper regions, where A. butcheri spends most of the year and spawns. In this study, the biological characteristics of A. butcheri in 2007-11 were determined and compared with those in 1993-95. Between these two periods, the condition factor for females and males of A. butcheri across their length ranges declined by 6 and 5%, respectively, and the parameters k and L∞ in the von Bertalanffy growth curves of both sexes underwent marked reductions. The predicted lengths of females and males at all ages ≥1 year were less in 2007-11 than in 1993-95 and by over 30% less at ages 3 and 6. The ogives relating maturity to length and age typically differed between 1993-94 and 2007-10. The L50s of 156 mm for females and 155 mm for males in 2007-10 were less than the corresponding values of 174 and 172 mm in 1993-94, whereas the A50s of 2.5 years for both females and males in 2007-10 were greater than the corresponding values of 1.9 and 2.0 years in 1993-94. The above trends in condition, growth and maturity parameters between periods are consistent with hypotheses regarding the effects of increasing hypoxia on A. butcheri in offshore, deeper waters. However, as the density of A. butcheri declined in offshore, deeper waters and increased markedly in nearshore, shallow waters, density-dependent effects in the latter waters, although better oxygenated, also probably contributed to the overall reductions in growth and thus to the changes in the lengths and ages at maturity.

Analysis of benthic macroinvertebrate samples at a higher taxonomic level than species, e.g. family, potentially provides a more cost-effective protocol for environmental impact assessments and monitoring as it requires less time, funds and taxonomic expertise. Using the AMBI database, species ecological group scores are shown to be coherent within families. Faunal data from a wide range of environmental impact scenarios in the north-eastern Atlantic demonstrate that AMBI, calculated from mean values for families, exhibits a strong linear relationship with species-level AMBI, the correlation improving by using square-root transformed rather than untransformed abundances. In many regions of the world, however, the sensitivity of benthic macroinvertebrates to environmental perturbations is unknown, precluding the use of AMBI for environmental assessments. Yet the families are essentially the same as in the AMBI database. The utility of family-level AMBI is tested using data for four south-western Australian estuaries previously subjected to environmental quality assessments, but where only 17 species of the 144 taxa are included in the AMBI database. Although family-level AMBI scores reflect differences in environmental quality spatially and temporally within an estuary, they do not follow variations in environmental quality among estuaries. Indeed, south-western Australia estuaries are numerically dominated by families with high AMBI scores, probably due to the detrimental effects of natural accumulations of organic material in estuaries with long residence times. As taxonomic distinctness follows trends in environmental quality among estuaries, as well as temporally and spatially within a system, it provides an appropriate substitute for assessing the 'heath' of microtidal estuaries.

Lampreys are one of two extant representatives of the earliest group of vertebrates, the agnathans or jawless fishes. The single species of the southern hemisphere lamprey family Geotriidae, Geotria australis, possesses the potential for pentachromatic color discrimination opposed to the mono- or dichromacy found in other lampreys. However, little is known of the retinal ganglion cell types that contribute to visual processing in G. australis. A quantitative morphological approach was used to distinguish and describe retinal ganglion cell types in G. australis. The morphology of retinal ganglion cells was revealed by retrograde biocytin labeling from the optic disc. Cells were digitally reconstructed, and somatic area and position and dendritic field size, density, tortuosity, and stratification were subjected to quantitative morphometric analyses. Cluster analysis, in conjunction with similarity profile analysis (SIMPROF), statistically identified five discrete monostratified retinal ganglion cell types, one of which may comprise two subtypes. Two bistratified types were identified separately, including a biplexiform and a bistratified subtype. The use of cluster analysis with SIMPROF provided a robust statistical technique for objectively identifying cell types whose characteristics were similar and significantly different from those of other types and thus provides an objective resolution of the problems posed by "lumpers vs. splitters" when designating cell types. The diversity of retinal ganglion cells suggests that visual information in the lamprey G. australis is processed in parallel streams, as in gnathostomes. These findings, together with the results of previous studies, indicate that the visual system of the lamprey G. australis represents the upper limit of visual complexity in extant agnathans.

This article is available open access from the publisher’s website through the link below. Copyright © 2014 Pak Publishing Group.

An extensive literature base worldwide demonstrates how spatial differences in estuarine fish assemblages are related to those in the environment at (bio)regional, estuary-wide or local (within-estuary) scales. Few studies, however, have examined all three scales, and those including more than one have often focused at the level of individual environmental variables rather than scales as a whole. This study has identified those spatial scales of environmental differences, across regional, estuary-wide and local levels, that are most important in structuring ichthyofaunal composition throughout south-western Australian estuaries. It is the first to adopt this approach for temperate microtidal waters. To achieve this, we have employed a novel approach to the BIOENV routine in PRIMER v6 and a modified global BEST test in an alpha version of PRIMER v7. A combination of all three scales best matched the pattern of ichthyofaunal differences across the study area (ρ = 0.59; P = 0.001), with estuary-wide and regional scales accounting for about twice the variability of local scales. A shade plot analysis showed these broader-scale ichthyofaunal differences were driven by a greater diversity of marine and estuarine species in the permanently-open west coast estuaries and higher numbers of several small estuarine species in the periodically-open south coast estuaries. When interaction effects were explored, strong but contrasting influences of local environmental scales were revealed within each region and estuary type. A quantitative decision tree for predicting the fish fauna at any nearshore estuarine site in south-western Australia has also been produced. The estuarine management implications of the above findings are highlighted.

Chronologies are developed from the otolith growth-increment widths of adult rock flathead (Platycephalus laevigatus) and longhead flathead (Leviprora inops) collected from three inter-connected embayments in temperate south-western Australia. Marginal increment trends on otoliths, in combination with the dendrochronological technique of crossdating, provide strong evidence that an opaque zone is formed annually in the otoliths of both species. Increment widths between opaque zones in the otoliths of individuals of P. laevigatus (maximum age 20 years) and L. inops (maximum age 21 years) were synchronised within and between species. The correlation between the two master otolith chronologies, i.e. mean standardised increment width for each year, was highly significant (P