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The Izak catshark Holohalaelurus regani and the yellow-spotted catshark Scyliorhinus capensis both occur over the continental shelf around South Africa and are often caught together as bycatch in d...

The zoogeography of marine Bryozoa around South Africa was investigated using published distribution records, museum catalogues, and an examination of previously unworked bryozoan material in (most...

The progressive expansion of human activities is causing unprecedented changes to marine ecosystems. In some cases, the extent of these changes may be so large as to generate ecosystems in which structure and functioning have no historical analogs (i.e. novel ecosystems). Here, we review the main abiotic and biotic drivers of change in the marine realm and provide a critical assessment of ecosystems for which there is empirical evidence of human-induced shifts into novel states. Our review indicates that there is evidence for human agency of changes, no-analog species composition and threshold crossing for a variety of marine ecosystems, including intertidal rocky shores, temperate and tropical reefs, estuaries and pelagic systems, while there is no definitive proof of irreversibility of changes. We discuss how a more thorough recognition of the novel ecosystem concept may help initiate conservation and restoration efforts in each of these systems.

Siphonophores are commonly considered to be useful indicators of water masses and water-mass movement, but their employment as such across the wider Southern Ocean has not so far been attempted. We redress this here using archived samples, collected during January-February 1993 along a transect from Cape Town to the South African National Antarctic Expedition (SANAE) base in Antarctica, and compare the patterns generated with those determined from a prior analysis of whole assemblages at lower taxonomic resolution. Twenty-one species were identified from 18 of the original 53 samples collected, and two distinct assemblages were confirmed as separated by the Sub-Antarctic Front. That to the south was characterised by low diversity and high abundance and was dominated by cold-water specialists, whereas that to the north comprised a larger number of subtropical and temperate species at low abundance. Assemblage structure was strongly influenced by the mixed layer depth, sea surface salinity and chlorophyllaconcentration, as well as mesozooplankton biomass. Congruence with the whole-assemblage study was high, indicating that this taxon can be suitably employed as a proxy in studies such as this. The study emphasises the value of archived plankton samples and makes a plea for better curation.

Jellyfish populations in the southeastern Atlantic off the coast of Namibia have increased subsequent to the decline of small pelagic fisheries at the end of the 1960s, although the environment the...

In the South Atlantic Ocean, the Subtropical Front (STF) separates warm-water copepod assemblages of high diversity from cold-water assemblages of lower diversity. Comparable information from the southern Indian Ocean are scarce. Here we test observations made in the southwest sector of the Indian Ocean using samples collected during 2009 from along the South West Indian Ridge (SWIR, ∼27 - 42° S). Distinct assemblages were associated with the Agulhas Return Current (ARC), the Sub-Tropical Front (STF) and Sub-Antarctic Front (SAF). Sixty-nine percent of the structure of the assemblages could be attributable to the temperature at both the surface and 200 m, the salinity and the fluorescence signal of surface waters and the depth of the upper mixed layer. Forty-nine copepod genera and 132 species were recorded. While richness was greatest in waters of the ARC and lowest in the SAF, copepods were most abundant in the latter and scarcest in the former. Mean prosome length decreased with increasing latitude, and assemblages of the ARC included greater numbers of carnivorous taxa than those associated with either the STF or the SAF. As in the Atlantic, the STF markedly influenced the relative distribution range of copepod assemblages above the South West Indian Ridge.

Although ctenophores can be conspicuous components of the plankton in coastal marine ecosystems, only six species have been formally described from around South Africa. Using photographs from local community scientists, we add a further three species (Cestum veneris, Beroe forskalii?,Ocyropsis maculata?) and six morphospecies to the regional fauna. These additions suggest that South Africa has a ctenophore fauna that is amongst the most diverse, globally; an observation in agreement with information from other taxa. Tips on how community scientists can improve their photographic contributions to understanding ctenophore diversity are provided.

Published information from the Western Indian Ocean (WIO) and new data from the South West Indian Ocean Ridge, are consolidated and combined to generate an updated biogeography of calanoid copepods. The WIO was divided into 75 5° grid squares, and a similarity matrix between grids was generated on the basis of presence:absence data for more than 172 species. Distinct assemblages are identified that correspond to the 1) coastal waters of Somalia, Kenya, Tanzania and northern Mozambique, 2) coastal and offshore waters of southern Mozambique and NE South Africa, 3) coastal and offshore waters of South Africa, 4) waters of the central WIO. The patterns observed are in agreement with surface circulation patterns in the region, and the influence of gyres and eddies on the distribution of some taxa is hypothesised. The coarse and qualitative nature of the data prevents us from identifying transitional faunas, as well as those associated with mesoscale features.

The process of species description is not random, and understanding the factors that influence when a species is first described (the date of first description, DoFD) allows us to target environments and/or species' traits to increase our knowledge of diversity. Such studies typically correlate species traits (e.g. maximum size, occupational depth) against DoFD, forgetting that species are not statistically independent of each other, owing to the inheritance of shared characteristics. A recent study of extant fishes by Costello et al. (2015) identified depth and geographic range size as the most important (of many) predictors of the DoFD, implying that newly described species will likely occupy restricted areas and occur deep in the water column. However, these authors failed to accommodate for “identity by descent” in their analyses. We correct that oversight here, and conclude that while the adjustments strengthen the associations between the different predictors and the DoFD, the overall affects are minimal and they do not materially change Costello et al.’s (2015) conclusions. This is briefly discussed.

Populations of Euphausia lucens over the shelf of the southern Benguela upwelling region could be self-maintaining. Alternatively, they could be continually refreshed by expatriates from the SWAtlantic that enter the system via South Atlantic Central Water in the south, before developing and then being lost through advection off Namibia. These two hypotheses are investigated here by examining geographic heterogeneity and molecular variation (cox1 and ND1) of the species across its distributional range in the Southern Hemisphere. Comparisons are made with E. vallentini, which is assumed to show panmixia associated with its circumglobal distribution between 50 and 608S. Phylogenetic analysis with mitochondrial 16S ribosomal RNA and cytochrome oxidase 1 (cox1) confirmed that E. lucens and E. vallentini represent sister taxa. Strong geographic structuring of cox1 and ND1 mtDNA genetic variation by ocean basin was recorded in E. lucens, indicating that neritic populations off South Africa are likely self-maintaining. This contrasts with the results for E. vallentini, which appears to occur as a single panmictic population across its distributional range. These differences are likely related to the habitats (neritic, E. lucens; oceanic, E. vallentini) occupied by each species. The results of the neutrality tests are consistent with demographic processes and suggest growth in E. lucens and equilibrium or shrinkage in E. vallentini. Although purifying selection cannot be ruled out in

Zooplankton biomass and distribution in the KwaZulu-Natal Bight were investigated in relation to environmental parameters during summer (January–February 2010) and winter (July–August 2010). Mean zooplankton biomass was significantly higher in winter (17.1 mg dry weight [DW] m−3) than in summer (9.5 mg DW m−3). In summer, total biomass was evenly distributed within the central bight, low off the Thukela River mouth and peaked near Durban. In winter, highest biomass was found offshore between Richards Bay and Cape St Lucia. Zooplankton biomass in each size class was significantly, negatively related to sea surface temperature and integrated nitrate, but positively related to surface chlorophyll a and dissolved oxygen. Zooplankton biomass was significantly related to bottom depth, with greatest total biomass located inshore (

Whether jellyfish are increasing or not in the global ocean is a subject of some debate, but the fact remains that when they bloom, jellyfish can negatively affect local economies. Despite this, there has been no robust debate about the idea of deliberately removing jellyfish as a means of population control. Here, we discuss the effects of fishing for jellyfish, either as a sustainable resource and/or as a way to simply reduce their nuisance value, on both individual jellyfish populations and the ecosystem. Given that the drivers influencing each local bloom are different, or that the effects of more widespread drivers may be manifested differently at each locale, our priority at population control/use needs to be more basic research on jellyfish. While we do not advocate a no-fishing approach, we emphasize the need to be cautious in embracing jellyfish fisheries as a panacea and we need to consider the management of each bloom on a case-by-case basis.

A total of 96 species of sponge were recorded in a bathymetric survey conducted within the iSimangaliso Wetland Park. Non-random processes are hypothesised to account for the decline in species richness with increasing depth, and the data add support to Rapoport’s rule. Morphological and colour diversity were strongly correlated and decreased with depth. Five communities could be identified at the 30% level of similarity using cluster analysis, and these correspond to intertidal and shallow subtidal (to 10 m), deep sub-photic zone (coral reefs: 10–30 m), deep reefs (40–90 m), canyon margin (100–140 m) and canyon (140–360 m). The data add support to recently hypothesised bathymetric zones around South Africa.

This work represents the first systematic analysis of the common Siphonophora from the Agulhas Current (South-West Indian Ocean). A total of 56 species of siphonophores was collected from a series of three largely epipelagic cruises between Algoa Bay and the Tugela River along the east coast of South Africa. Although no readily identifiable Cystonectae were observed, four families and nine species of Physonectae were collected. Calycophorae were the most common and abundant siphonophores, and five families and 47 species were recorded. Details of locations where each species was collected are given, but descriptions and illustrations are provided only for taxa that represent new records for the region.

The foraminifera of Gelidium pristoides were examined on exposed and sheltered shores around False Bay, South Africa, during the summer and winter of 1998/1999. Twenty-five species were recognized, seven are potentially new. Multivariate statistics indicated that the assemblages on plants from exposed shores were distinct from those on sheltered shores, and two species of foraminifera were confined to exposed shores. Plant size and the quantity of trapped sediment were positively correlated, and plants on exposed shores were significantly bigger than those on sheltered shores. Plant size and sediment weight were linked to assemblage diversity and abundance; assemblages on exposed shores were generally more diverse and abundant than those of sheltered shores. Different species dominated on the two shore types, and larger foraminifera tended to be more common on exposed shores.

A total of 242 zooplankton samples from the upper 100 m of the water column was collected discontinuously from March 1997 to January 1999 off the Orange River mouth on the west coast of southern Africa. Six species of hydromedusae were recovered at generally low abundance, of which Euphysa aurata, Leuckartia octona and Proboscidactyla menoni were dominant. E. aurata and L. octona showed evidence of seasonality in abundance. The low diversity of the fauna was remarkable and it is hypothesized that this might be attributable in part to sedimentation from the Orange River, and in part to locally weak circulation and the wide extent of the continental shelf.

Published and unpublished records of epipelagic calycophoran siphonophores from around southern Africa were examined for zoogeographic structure. There is a close match between prevailing patterns of surface ocean circulation and zoogeography, which while similar to previous studies of intertidal taxa and euphausiids, is different from them in some key details. Separate subtropical provinces are associated with both the Angola and Agulhas Currents, and the latter system has a marked influence on the composition of (warm-temperate) assemblages along the south coast of South Africa. The nearshore waters in the Benguela upwelling ecosystem (cold temperate) are distinct, but the Lüderitz upwelling cell does not appear to act as an internal boundary within the Benguela ecosystem, as has been previously noted for benthic communities. Species richness is greater in oceanic than coastal waters, and peaks in subtropical waters. High diversity is also noted offshore in the area between Capes Agulhas and Columbine, where water of Indian, Southern and Atlantic Ocean interact. Indicator species for each major water mass were tentatively identified.

Changes in the composition of the assemblage of medusae and ctenophores were exam- ined daily over a period of 28 d, encompassing 3 upwelling events in a non-advective environment within the southern Benguela ecosystem. The relationships between assemblage composition and the environment were analysed using canonical correspondence analyses. Although distinct assem- blages were associated with upwelling itself, as well as with the periods of water column stabilisation and stratification, indicator species for the assemblages could not be identified. This reflected the near ubiquitous nature of most assemblage members, and their probable response to historical (unmeasured) environmental variables. That notwithstanding, it is clear that short-term changes in characteristics of the surface and deeper water environment are reflected by short-term changes in the composition of the gelatinous zooplankton assemblage. This is more reminiscent of phytoplank- ton than holozooplankton and probably reflects the meroplanktic nature of most assemblage mem- bers.

In a first effort to understand interactions between anchovy Engraulis capensis and sardine Sardinops sagax in the field, the size composition of the diet of these two species from a number of mixed shoals was examined. Although both species consumed similar types of food (crustacean eggs and nauplii, and copepods), sardine generally consumed significantly smaller prey (modal size-class generally 300 μm) than anchovy (modal size-class generally between 600 and 900 μm). No single explanation can be used to account for these results, and it is suggested that they are the product of differences in gill-raker morphology, feeding behaviour and within-shoal position. These results support previous single-species laboratory studies and suggest that competition between the two species in the field may be limited.

The feeding biology and the vertical migration of Sagitta friderici were examined over 24 h at two stations in the southern Benguela during spring (October) 1987. Together with studies conducted during summer (February 1991) and winter (May 1984), they serve to allow valuable generalizations of the biology and ecology of this abundant chaetognath. Populations migrate vertically and feed nocturnally, although the timing and the extent of migration vary between studies. S. friderici exhibits ontogenetic layering and the cross-shelf distribution of maturity stages differs, suggesting that it is able to take advantage of cross-shelf water movement in order to maintain populations in the nearshore waters of the West Coast. S. friderici prey almost exclusively on copepods (cannibalism is rare), and there is a positive relationship between the lengths of predator and prey that is influenced by the size structure of the prey environment. This casts doubt on the validity of a chaetognath species-specific relations...

The impact of inorganic sediments on rocky shore meiofauna was investigated in relation to tidal elevation, using artificial “algal” mats of differing complexity. Sediment accumulation was correlated with habitat structure and increased at higher elevations. The water content and retention time of mats was similarly related to sediment content and mat structure. The meiofauna was numerically dominated by small interstitial forms, notably harpacticoid copepods, copepod nauplii and nematodes. Densities recorded in the high shore were as great as those in the low intertidal, although diversity (especially of larger forms) and biomass were markedly lower. These patterns are discussed in relation to habitat structure and sediment content. By retaining water, sediments can create moderately stable environments within algal mats on the high shore, to the advantage of small meiofauna. As a result of the increasingly favourable environment towards the bottom of the shore, meiofaunal diversity and biomass increased. Traditionally, the positive relationship between structural complexity and meiofaunal abundance and diversity has been viewed in terms of the number of habitats and the provision of refugia from predators. It is concluded here that complexity and sediments also influence microenvironmental conditions and that this in turn has an important impact on meiofaunal communities.

In 1984 and 1985 algal, macrofaunal and meiofaunal standing stocks were estimated on a exposed rocky shore along the west coast of False Bay, South Africa, using comparable, area-based sampling techniques. The shore supported a rich growth of algae, particularly in summer, when a maximum standing crop of 403 g m-2 was recorded in the low shore. In winter, the largest component of macrofaunal biomass comprised the filter-feeding barnacle Tetraclita serrata, which attained 75 g m-2 in the middle balanoid; but as a result of late recruitment and high mortality of this species, the summer shore was dominated by herbivorous gastropods, particularly Patella cochlear, which attained a maximum biomass of 66 g m-2 on the low shore. Meiofaunal numbers and biomass were closely correlated to the distribution of algal turfs and associated trapped sediments. Numerically, the most important components of the meiofauna were nematodes and copepods, while the biomass was more evenly shared among foraminifera, minute gastropods, copepods and insect larvae. Numbers and biomass peaked in the lower balanoid during winter (1.9×106 individuals, or 8.5 g m-2). Macrofauna:meiofauna numbers and biomass ratios are presented for each zone and the distribution patterns discussed in relation to the conditons in each. Numerically, meiofauna exceed macrofauna by an overall ratio of 1:391, with values ranging from 1:556 in the lower balanoid to 1:18 in the Littorina zone. Macrofaunal biomass exceeds that of meiofauna in all zones by an overall ratio of 10:1, but values range from 2.1:1 in the upper balanoid to 48:1 in the middle balanoid. By incorporating turnover ratios extrapolated from the literature, mean annual productivity ratios have been calculated. These indicate that macrofauna account for 75% of total secondary production and meiofauna for 25%. Failure to incorporate meiofauna in analyses of energy flow on rocky shore ecosystems would thus lead to considerable errors. The possible trophic role of meiofauna in such systems is discussed.