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The past few years have seen a noticeable increase in the emergence of infectious diseases in wildlife, especially vector‐borne diseases, presenting a challenge for the conservation of endangered species. One such vector‐borne disease, avian malaria (Plasmodium spp.) is on the rise in New Zealand avifauna, threatening bird populations that are among the most extinction‐prone in the world. Furthermore, recent reports have outlined an increase in deaths of native iconic bird species specifically due to this disease. In order to help manage breakouts of this pathogen at a local scale, we need a better understanding of potential drivers of the emergence of avian malaria in wild New Zealand avifauna. Here, we set to test the role of climatic drivers in synchronizing contacts between avian hosts and vectors, assess the temporal stability of transmission dynamics between years, and determine the role of introduced species in causing spill‐over of this pathogen towards native species. Our study focused on three sites that were sampled regularly during two consecutive years in the austral summer, each site being adjacent to a breeding colony of Yellow‐eyed penguins (Megadyptes antipodes). Our results reveal an overall temporal stability of avian malaria incidence patterns, with a decrease in infection throughout the austral summer for both sampled years. Moreover, we highlight a phylogenetic signal among sampled bird species, with introduced species being more heavily infected by avian malaria than their native counterparts. In contrast, we found no effect of the two climatic drivers investigated, temperature and rainfall, on mosquito abundance. Our results suggest a strong effect of alien species acting as reservoirs for diseases spilling‐over towards immunologically naïve species, and provide conservation managers with a critical timeframe to control avian malaria breakouts. [ABSTRACT FROM AUTHOR]

Acanthocephalans constitute a relatively small phylum of dioecious helminths that infect invertebrate intermediate and vertebrate paratenic and definitive hosts. Like most parasites, acanthocephalans are usually overlooked in biodiversity studies, although they can have significant impacts on their host's health and the structure of surrounding communities. In this study, we present morphological and molecular data from an extensive biodiversity survey of acanthocephalans infecting a range of marine animals in a coastal marine ecosystem in New Zealand. We recovered 13 acanthocephalan species infecting 32 of the 168 free-living animal species investigated, 1 of which is a new geographic record for New Zealand (Gorgorhynchoides queenslandensis), 9 of which constitute new host records, and at least 2 that are species new to science. The data presented here provide a baseline dataset to which future assessments of changes in diversity and distribution of acanthocephalans can be compared. [ABSTRACT FROM AUTHOR]

Littorinid snails are present in most coastal areas globally, playing a significant role in the ecology of intertidal communities. Laevilitorina is a marine gastropod genus distributed exclusively in the Southern Hemisphere, with 21 species reported from South America, the sub-Antarctic islands, Antarctica, New Zealand, Australia and Tasmania. Here, an updated database of 21 species generated from a combination of sources is presented: 1) new field sampling data; 2) published records; 3) the Global Biodiversity Information Facility (GBIF) and The Atlas of Living Australia (ALA), to provide a comprehensive description of the known geographic distribution of the genus and detailed occurrences for each of the 21 species. The database includes 813 records (occurrences), 53 from field sampling, 174 from the literature, 128 from GBIF, and 458 from ALA. West Antarctica had the highest species richness (8 species), followed by sub-Antarctic islands of New Zealand (4 species) and the south-east shelf of Australia (4 species). The provinces of Magellan, New Zealand South Island, and sub-Antarctic Islands of the Indian Ocean include two species each. This study specifically highlights reports of L. pygmaea and L. venusta, species that have been almost unrecorded since their description. Recent advances in molecular studies of L. caliginosa showed that this species does not correspond to a widely distributed taxon, but to multiple divergent lineages distributed throughout the Southern Ocean. Ongoing molecular and taxonomic studies are necessary for a better understanding of the diversity and biogeography of this genus. [ABSTRACT FROM AUTHOR]

Some heritable endosymbionts can affect host mtDNA evolution in various ways. Amphipods host diverse endosymbionts, but whether their mtDNA has been influenced by these endosymbionts has yet to be considered. Here, we investigated the role of endosymbionts (microsporidians and Rickettsia) in explaining highly divergent COI sequences in Paracalliope fluviatilis species complex, the most common freshwater amphipods in New Zealand. We first contrasted phylogeographic patterns using COI, ITS, and 28S sequences. While molecular species delimitation methods based on 28S sequences supported 3–4 potential species (N, C, SA, and SB) among freshwater lineages, COI sequences supported 17–27 putative species reflecting high inter‐population divergence. The deep divergence between NC and S lineages (~20%; 28S) and the substitution saturation on the 3rd codon position of COI detected even within one lineage (SA) indicate a very high level of morphological stasis. Interestingly, individuals infected and uninfected by Rickettsia comprised divergent COI lineages in one of four populations tested, suggesting a potential influence of endosymbionts in mtDNA patterns. We propose several plausible explanations for divergent COI lineages, although they would need further testing with multiple lines of evidence. Lastly, due to common morphological stasis and the presence of endosymbionts, phylogeographic patterns of amphipods based on mtDNA should be interpreted with caution. [ABSTRACT FROM AUTHOR]

Parasitic helminths with complex life cycles require multiple hosts in a particular order to complete their life cycles. Although almost all helminths infect invertebrates at some point in their life cycle, we know very little about which species of invertebrates harbor parasites compared with what is known for vertebrates. In New Zealand, <1% of marine invertebrates that may be expected to host parasites have records of parasite infections. This is a strong indication that our knowledge of invertebrate parasites within marine ecosystems is highly limited. Here, we provide the first comprehensive parasite–host checklist including data from the literature and newly discovered infections of parasitic helminths infecting marine invertebrates in New Zealand. Including both pre‐existing and newly found data from our survey, we present data on 73 parasite taxa (five acanthocephalans, 13 cestodes, nine nematodes, and 46 trematodes) infecting 62 marine invertebrate species in New Zealand. In addition, we compile existing and new genetic data for many of these parasites, as a useful tool for future studies of parasite biodiversity and phylogenetics. [ABSTRACT FROM AUTHOR]

A full account of the world's species is important for understanding how natural systems are structured, how they function and how they will respond to natural and anthropogenic pressures in the future. Despite the well-known importance of parasites in natural systems, they are too often underrepresented from studies on biodiversity and ecological functioning. In this review, we provide a quantitative synthesis of the current state of knowledge of helminth biodiversity within New Zealand's marine environment. We report that records of parasitic helminths within New Zealand marine animals are few and uneven across host taxa. A large proportion of parasite species are taxonomically unresolved, with some differences across parasite taxa. Few parasites have their whole life cycles resolved, and the majority are only reported from one host species at one life stage. Most endemic host species are yet to be investigated for helminths and there is likely an abundance of endemic parasite diversity yet to be discovered. Host species of greater conservation concern are being investigated for helminths less frequently than species of low conservation concern. We conclude that little is known about parasitic helminths in New Zealand's marine environment and make recommendations on how to improve this situation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sympatric hairworms follow different transmission routes through host communities. • Some dead-end hosts represent important population sinks for hairworms. • Some host species can simultaneously contribute and hinder the hairworm life cycle. • Certain key host species can alter the flow of parasites in a community. • Relative host community composition can effectively impact parasite transmission. Community composition, including the relative density of each host species, plays a vital role in the transmission of parasites or disease in freshwater ecosystems. Whereas some host species can effectively transmit parasites, others can act as dead ends (non-viable transmission routes), accumulating large numbers of parasites throughout their life, thus becoming important sinks for parasite populations. Although population sinks have been identified in certain host-parasite systems, robust field estimates of the proportions of parasites that are lost to these hosts are lacking. Here, we quantified the distribution of encysted larval hairworms (phylum Nematomorpha), common parasites in lotic ecosystems, in two subalpine stream communities of New Zealand. With parasite and host population densities calculated per m2, we identified which host species most likely contributed to the transmission of three sympatric hairworm morphotypes identified in both streams, and which species acted as population sinks. We also tested for seasonal patterns and peaks in the abundance of each morphotype in the two communities over the sampling season. Finally, we tested whether hosts emerging from the streams had comparable abundances of hairworm morphotypes throughout the sampling period. For each morphotype, different key sets of host species harboured more hairworms on average (abundance) than others, depending on the stream. For one morphotype in particular, two species of hosts were found to be important population sinks that inhibited over a third of these parasites from completing their life cycle. We also observed a clear peak in abundance for another hairworm morphotype during summer. Our data suggest that hosts emerging from the streams matched their aquatic counterparts with respect to hairworm abundance, indicating no infection-dependent reduction in emergence success. Our findings suggest that, depending on relative community composition, sympatric parasites follow different host transmission pathways, some of which lead to dead ends that potentially impact overall infection dynamics. In turn, this information can help us understand the spread or emergence of disease in both freshwater and terrestrial environments, since hairworms infect terrestrial arthropods to complete their life cycle. [ABSTRACT FROM AUTHOR]

Anthropogenic changes can have dramatic effects on wild populations. Moreover, by promoting the emergence of vector-borne diseases in many ecosystems, those changes can lead to local extinction of native wildlife. One of those diseases, avian malaria, has been shown to be on the rise in New Zealand, threatening native bird species that are among the most extinction-prone in the world. It is thus of prime importance to better understand the potential cascading effects that anthropogenic modifications have on those fragile species. Here, we aim to test how long-lasting modification to regional environmental filters can subsequently alter local biotic filters, in turn promoting the emergence of avian malaria in New Zealand avian communities. To this end, we used Bayesian structural equation modelling to unravel the drivers of disease emergence within the complex interplay between landscape and local species pools. We show that altered landscape, quantified through a lower enhanced vegetation index, leads to more infections in Turdus spp. and modification in avian community composition, potentially raising the probability of infection for other species in the community. In addition, we show that climatic variables associated with the presence of vectors play a predominant role in shaping the regional pattern of avian malaria occurrence. Our results suggest long-lasting impacts of anthropogenic changes on regional environmental filters and demonstrate that conservation efforts should align toward restoring the landscape to prevent further emergence of infectious diseases in wild ecosystems. [ABSTRACT FROM AUTHOR]

Dedicated studies on aquatic disease in New Zealand began in 1974, inspired by a developing aquaculture industry. Since then, two main aquatic disease study areas have emerged: (1) aquatic disease ecology and (2) diseases of commercial species. Progress over the past 20-years has been made by only a small number of researchers and aquatic disease in New Zealand has not received much attention from the wider marine science community. In 2020, the aquaculture industry continues to grow, and disease remains a threat to the industry's viability. However, additional factors such as climate change, invasive species, and pollution, have emerged as future threats for aquatic disease in wild and farmed populations, which are currently understudied. Here, we provide a review of studies on aquatic disease ecology and commercial species carried out in New Zealand. We also present how climate change, pollution and invasive species could influence future aquatic disease dynamics and identify where future research effort is required to address knowledge gaps. The emergence of consequential aquatic diseases overseas highlights wider attention across marine science disciplines is needed to progress and diversify aquatic disease studies in New Zealand. [ABSTRACT FROM AUTHOR]

Diseases, and the parasitic organisms that cause them, can impact aspects of ecosystems ranging from altering food web connectivity to population dynamics. Apart from interspecific interactions, parasites can affect how their hosts behave with conspecifics, such as during competition for resources. Fish are important hosts to a variety of parasite taxa that can, through physical impairment or invasion of sense organs, affect how they interact with conspecifics for food, territory, or mates. In New Zealand, the common bully Gobiomorphus cotidianus plays host to a variety of parasites, encysting throughout the body (Apatemon sp.) or residing within the eyes (Tylodelphys darbyi). We hypothesized that fish with lower levels of infection would secure territories closer to a food patch and be more likely to tolerate sharing that territory. Our experiments show that parasites infecting different areas may have variable impacts on how far the host positions itself from a food patch and the likelihood that it shares its territory. Fish with higher intensities of T. darbyi tended to be closer to the food patch, but Apatemon sp. did not show a similar pattern. Higher infection levels of both parasites were statistically associated with bullies being less likely to share territory. Further, bigger fish were less likely to share their territory at higher intensities infection, and we observed individual variation in a fish's response between trials. Our findings support that parasites matter in ecological interactions but also emphasize the context dependence of their effects. [ABSTRACT FROM AUTHOR]

Climate change-related increases in temperature will influence the interactions between organisms, including the infection dynamics of parasites in ecosystems. The distribution and transmission of parasites are expected to increase with warmer temperature, but to what extent this will affect closely related parasite taxa living in sympatry is currently impossible to predict, due to our extremely limited understanding of the interspecific variation in transmission potential among parasite species in changing ecosystems. Here, we analyse the transmission patterns of four trematode species from the New Zealand mudsnail Potamopyrgus antipodarum with different life cycles and transmission strategies under two temperature scenarios, simulating current and future warmer temperatures. In a comparative experimental study, we investigated the effects of temperature on the productivity, movement and survival of the parasites' transmission stages (cercariae) to quantify the net effect of temperature on their overall transmission potential. Our results show that increases in temperature positively affect cercarial transmission dynamics, yet these impacts varied considerably between the cercariae of different trematode species, depending on their host-searching behaviour. These different species-specific transmission abilities as well as the varying individual patterns of productivity, activity and longevity are likely to have far-reaching implications for disease dynamics in changing ecosystems, since increases in temperature can shift parasite community structure. Due to the parasites' capacity to regulate the functioning of whole ecological communities and their potential impact as disease agents, understanding these species-specific parasite transmission traits remains a fundamental requirement to predict parasite dynamics under changing environmental conditions. [ABSTRACT FROM AUTHOR]

Penguins are the only extant family of flightless diving birds. They currently comprise at least 18 species, distributed from polar to tropical environments in the Southern Hemisphere. The history of their diversification and adaptation to these diverse environments remains controversial. We used 22 new genomes from 18 penguin species to reconstruct the order, timing, and location of their diversification, to track changes in their thermal niches through time, and to test for associated adaptation across the genome. Our results indicate that the penguin crown-group originated during the Miocene in New Zealand and Australia, not in Antarctica as previously thought, and that Aptenodytes is the sister group to all other extant penguin species. We show that lineage diversification in penguins was largely driven by changing climatic conditions and by the opening of the Drake Passage and associated intensification of the Antarctic Circumpolar Current (ACC). Penguin species have introgressed throughout much of their evolutionary history, following the direction of the ACC, which might have promoted dispersal and admixture. Changes in thermal niches were accompanied by adaptations in genes that govern thermoregulation and oxygen metabolism. Estimates of ancestral effective population sizes (Ne) confirm that penguins are sensitive to climate shifts, as represented by three different demographic trajectories in deeper time, themost common (in 11 of 18 penguin species) being an increased Ne between 40 and 70 kya, followed by a precipitous decline during the Last Glacial Maximum. The latter effect is most likely a consequence of the overall decline in marine productivity following the last glaciation. [ABSTRACT FROM AUTHOR]

In parasites that strongly rely on a host for dispersal, geographic barriers that act on the host will simultaneously influence parasite distribution as well. If their association persists over macroevolutionary time it may result in congruent phylogenetic and phylogeographic patterns due to shared geographic histories. Here, we investigated the level of congruent evolutionary history at a regional and global scale in a highly specialised parasite taxon infecting hosts with limited dispersal abilities: the microsporidians Dictyocoela spp. and their amphipod hosts. Dictyocoela can be transmitted both vertically and horizontally and is the most common microsporidian genus occurring in amphipods in Eurasia. However, little is known about its distribution elsewhere. We started by conducting molecular screening to detect microsporidian parasites in endemic amphipod species in New Zealand; based on phylogenetic analyses, we identified nine species‐level microsporidian taxa including six belonging to Dictyocoela. With a distance‐based cophylogenetic analysis at the regional scale, we identified overall congruent phylogenies between Paracalliope, the most common New Zealand freshwater amphipod taxon, and their Dictyocoela parasites. Also, hosts and parasites showed similar phylogeographic patterns suggesting shared biogeographic histories. Similarly, at a global scale, phylogenies of amphipod hosts and their Dictyocoela parasites showed broadly congruent phylogenies. The observed patterns may have resulted from covicariance and/or codispersal, suggesting that the intimate association between amphipods and Dictyocoela may have persisted over macroevolutionary time. We highlight that shared biogeographic histories could play a role in the codiversification of hosts and parasites at a macroevolutionary scale. [ABSTRACT FROM AUTHOR]

A prerequisite for a parasitic manipulation to be considered adaptive is that it confers a fitness benefit to the parasite, such as increased transmission to another host. These manipulations can involve alterations to a wide range of host phenotypic traits, including microhabitat choice. Eye flukes of the trematode family Diplostomidae use fish as intermediate hosts and must be transmitted by predation to a piscivorous bird. In New Zealand, the diplostomid Tylodelphys darbyi infects the eyes of a widespread endemic freshwater fish, the common bully Gobiomorphus cotidianus. Within the eye, T. darbyi metacercariae achieve large sizes and move freely about the aqueous and vitreous humors of the eye. We hypothesized that higher intensities of T. darbyi would (i) cause bullies to show increased activity and spend more time moving about in open space (i.e., more conspicuous, risky microhabitat) and (ii) reduce their ability to compete for shelter with fish harboring lower infection levels. Our experiments showed that heavily infected fish were more active and spent more time in the open, although the effect was age-dependent, with immature fish displaying decreases in activity and time spent in the open with increasing intensities of infection. We also demonstrated that heavily infected female bullies have a lower probability of using shelter, but males show the opposite pattern. It is possible that using more risky microhabitats increases the likelihood of the fish being eaten by the parasite's predatory avian definitive hosts. However, our findings indicate that age- and sex-dependent effects call for a more nuanced interpretation. [ABSTRACT FROM AUTHOR]

Marine mammals are long-lived top predators with vagile lifestyles, which often inhabit remote environments. This is especially relevant in the oceanic waters around New Zealand and Australia where cetaceans and pinnipeds are considered as vulnerable and often endangered due to anthropogenic impacts on their habitat. Parasitism is ubiquitous in wildlife, and prevalence of parasitic infections as well as emerging diseases can be valuable bioindicators of the ecology and health of marine mammals. Collecting information about parasite diversity in marine mammals will provide a crucial baseline for assessing their impact on host and ecosystem ecology. New studies on marine mammals in New Zealand and Australian waters have recently added to our knowledge of parasite prevalence, life cycles and taxonomic relationships in the Australasian region, and justify a first host–parasite checklist encompassing all available data. The present checklist comprises 36 species of marine mammals, and 114 species of parasites (helminths, arthropods and protozoans). Mammal species occurring in New Zealand and Australian waters but not included in the checklist represent gaps in our knowledge. The checklist thus serves both as a guide for what information is lacking, as well as a practical resource for scientists working on the ecology and conservation of marine mammals. [ABSTRACT FROM AUTHOR]

Parasites manipulating their host to facilitate trophic transmission is a widespread and diverse phenomenon. Trematode eye‐flukes in the family Diplostomidae infect a variety of fish species as metacercariae, many residing in the eyes. A recently described diplostomid, Tylodelphys darbyi, from the South Island of New Zealand has been found to infect common bully Gobiomorphus cotidianus, an endemic freshwater fish. Within the fish, the metacercariae move about freely in the liquid parts of the eye and are quite large. We hypothesized that increasing intensity of T. darbyi infection will result in increasing visual impairment, thus reducing the ability of G. cotidianus to identify and react to a predatory threat. To test this hypothesis, we performed experiments to (a) examine the fish's reaction to a purely visual predator cue and (b) test their ability to avoid simulated predation under natural levels of infection. Among the 64 fish used in our experiments, T. darbyi had a prevalence of 98.7% with an average of 17.6 worms per fish. However, there was no relationship between T. darbyi intensity and either the fish's reaction to a visual predator stimulus or their ability to escape a simulated predator. Our findings indicate that despite being present in large numbers in the eyes of its fish host, the parasite appears incapable of improving its chances of trophic transmission to its avian definitive host. The results also suggest that the fish G. cotidianus could be using other senses (e.g., olfaction and lateral line) to compensate for visual impairment, and detect and respond to predators. [ABSTRACT FROM AUTHOR]

Neorickettsia are endosymbiotic bacteria that infect digeneans (Trematoda). These bacteria are of interest worldwide because of their ability to move from the parasite to its host, where they can cause serious diseases of humans and animals. While several disease-forming species of Neorickettsia have been well studied, and numerous Neorickettsia types have been identified in regions such as North America and parts of Asia, records from other locations are sparse. To date, there have been no reports of Neorickettsia from New Zealand. We screened ten species of digeneans infecting seven native gastropod species (both marine and freshwater) found near Dunedin, New Zealand, for the presence of neorickettsial infections. A >1300 bp long section of 16S rRNA belonging to a Neorickettsia bacterium was isolated from opecoelid digeneans of two individuals of the mudflat topshell snail Diloma subrostrata. These sequences represent the first evidence of neorickettsial infection in native New Zealand animals and are also the first Neorickettsia found in digeneans of the family Opecoelidae. [ABSTRACT FROM AUTHOR]

The mosquito-borne disease avian malaria (Plasmodium spp.) has impacted both captive populations and wild individuals of native New Zealand bird species. However, whether or not it is a cause of concern to their wild populations is still unclear. In Hawaii, the disease has been a major factor in the population declines of some native forest bird species, often limiting their elevational distribution due to an inverse relationship between force of infection and elevation. While studies have investigated latitudinal patterns of infection in New Zealand, elevational patterns are unexplored. To address this, a survey was conducted in Nelson Lakes National Park, a site experiencing native bird declines in which disease has been suggested as playing a role, to investigate whether there is a similar inverse relationship in New Zealand. Results from blood samples (n = 436) collected over three seasons across a broad elevational range (650–1400 m) support there being such a relationship. In addition, an overall higher prevalence in non-native (14.1%) versus native birds (1.7%) may indicate differential impacts on these two groups, while particularly high prevalence in non-native Turdus spp. supports previous suggestions that they are key reservoir hosts for the disease. Overall, these findings add weight to the hypothesis that avian malaria is playing a role in ongoing declines of native New Zealand birds. [ABSTRACT FROM AUTHOR]

In many host-parasite systems, infection risk can be reduced by high local biodiversity, though the mitigating effects of diversity are context dependent and not universal., In aquatic ecosystems, local fauna can reduce the transmission success of parasite free-swimming infective stages by preying on them, acting as decoy hosts, or physically interfering with transmission. However, most prior research has focused on the effect of a single non-host organism at a time and/or has been performed under simplified and artificial conditions., Here, using data on 11 trematode species sampled in different New Zealand lakes, we test whether local biodiversity affects infection risk in target second intermediate hosts, as well as total parasite population size (number of parasites per m2), under natural conditions. We considered four components of local biodiversity: total biomass of non-host fish species, diversity (Simpson index) of non-host benthic invertebrates, total density of zooplankton and macrophyte biomass. Our analyses also accounted for host density, a known determinant of parasite prevalence, intensity of infection and total parasite population density., The only influence of local biodiversity we detected was a negative effect of the diversity of non-host benthic invertebrates on the prevalence achieved by trematodes in their second intermediate hosts: that is, the proportion of individual hosts that are infected. Interestingly, this effect was discernible in all 11 trematode species considered here, even if very weak within some species., Our findings suggest that higher non-host benthic diversity may generally decrease infection risk for target hosts including snails, arthropods and fish. However, reduced infection success did not automatically mean smaller overall parasite population size, as other factors can maintain the parasite population in the face of high local diversity of non-hosts. [ABSTRACT FROM AUTHOR]

Parasitic nematodes of the family Mermithidae were found to be infecting the introduced European earwig Forficula auricularia (Dermaptera: Forficulidae) in Dunedin, South Island, New Zealand. Adult females were later collected from various garden plants while depositing eggs. These mermithid specimens were identified morphologically as Mermis nigrescens Dujardin, 1842. A genetic distance of 0.7% between these specimens and a M. nigrescens isolate from Canada (18S rRNA gene), suggests that they have diverged genetically, but there are currently no available comparable sequences for the European M. nigrescens. Two additional nuclear fragments were also amplified, the 28S rRNA and the ribosomal DNA first internal transcribed spacer (ITS1), providing a basis for future studies. Bearing in mind the morphological similarity with other reported M. nigrescens and the lack of sequence data from other parts of the world, we retain the name M.nigrescens, and suggest that the species may be found to represent a complex of cryptic species when more worldwide data are available. Herein, we present a brief description of the post-parasitic worms and adult females, along with an inferred phylogeny using 18S rRNA gene sequences. [ABSTRACT FROM AUTHOR]

The comparative analysis of genetic structure and phylogeography of marine species can reveal the relative importance of common biogeographic barriers and species-specific evolutionary histories. In the present study, mitochondrial COI sequences from a total of 724 individuals collected from 38 localities throughout New Zealand during 2006 and 2007 were used to examine the genetic structure and demographic histories of the intertidal gastropods Zeacumantus subcarinatus and Zeacumantus lutulentus. For both species, results revealed isolation of populations located along the northern South Island and southern and western North Island, and extensive genetic structure throughout the remainder of their ranges. Despite this, long-distance dispersal and secondary admixture of divergent haplotypes was evident, especially for the widespread Z. subcarinatus. These findings reveal the importance of common barriers to gene flow and highlight how the interaction of inherent dispersal limitations of direct-developing marine organisms and periodic long-distance movements can produce complex genetic patterns. [ABSTRACT FROM AUTHOR]

Metacestodes are often found in the body cavity of the common bully (Gobiomorphus cotidianus McDowall), from freshwater habitats in Otago, New Zealand. Identification of metacestodes relies only on the number, size and shape of the rostellar hooks. To attempt species determination, we cultivated metacestodes in vitro for up to 23 days, during which they matured to at least the male stage of development, although female organs were not discernable. Identified as members of the genus Paradilepis Hsü, 1935 (family Gryporhynchidae), these specimens are compared to previously described species, in particular P. minima (Goss, 1940), from Australia, the closest species, both geographically and morphologically. Although the size of scolex, suckers and proglottids differ significantly from those of P. minima, we are cautious about interpreting ‘adults’ grown in vitro, because we are unsure whether the artificial conditions alter development. For this reason, and because of the lack of female organs, we refrain from erecting a new species, and refer to the specimens as Paradilepis cf. minima until such time as the adults are found in the definitive host. With this proviso we present here a description of the in vitro-grown worms and the metacestodes as a preliminary study of this cestode. A molecular analysis of small subunit (SSU) rDNA sequences, shows the position of P. cf. minima and another gryporhynchid, Neogryporhynchus cheilancristrotus (Wedl, 1855), to be equivocal, but confirms their exclusion from the Dilepididae and Hymenolepididae. This is the first record of a gryporhynchid from New Zealand, and the first from the fish family Eleotridae. [ABSTRACT FROM PUBLISHER]

Abstract: Anthropogenic stressors such as pollutants can modulate levels of parasitic infections in aquatic animals by suppressing host immunity or through some other mechanisms. One such mechanism could involve increases in either the quantity or quality of infective stages produced by parasites. We investigated the effect of exposure of infected snails, Potamopyrgus antipodarum, to different concentrations of the widely-used herbicide glyphosate, on (i) the production of infective cercariae by three trematode species, Coitocaecum parvum, Apatemon sp. and an undescribed renicolid, and (ii) the survival of cercariae of the latter species. For all three trematode species, infected snails exposed over a month to low (0.36mga.i.L−1) or medium (3.6mga.i.L−1) formulated glyphosate concentrations released between 1.5 and 3 times more cercariae per day than snails under control conditions. The similar pattern seen in all trematodes suggests a general weakening of the host benefiting any of its parasites rather than some parasite species-specific mechanism. In addition, the survival of renicolid cercariae improved with increasing glyphosate concentrations, with cercariae living about 50% longer in the medium concentration (3.6mga.i.L−1) than in control conditions. Our results demonstrate a clear interaction between glyphosate pollution and parasitism by trematodes in freshwater systems, occurring at glyphosate concentrations recorded in aquatic habitats, and within the environmental exposure limit allowed in New Zealand freshwaters. Future risk assessments and toxicity tests need to consider indirect impacts resulting from infections to invertebrate and vertebrate species penetrated by cercariae and serving as second intermediate hosts of trematodes. [Copyright &y& Elsevier]

[Display omitted] • Parasitic organisms exhibit remarkable diversity in their life cycles. • Less than an estimated 5% of marine parasite life cycles are resolved. • New insights into the life cycle of parasites in a New Zealand coastal ecosystem are provided. • Host species and taxa most important for parasite life cycles were identified. • This study acts as a starting point to understand how parasites travel through natural systems to complete their life cycles. Parasitic helminths exhibit remarkable diversity in their life cycles, although few parasite species have their whole life cycles resolved. Owing to the fact that parasite life stages within hosts are often not comparable using morphological data, genetic data provides convincing evidence of transmission pathways between intermediate and definitive hosts. We took this approach to an ecosystem level, genetically matching parasite (acanthocephalan, cestode, nematode and trematode) life stages across a broad taxonomic range of intermediate and definitive hosts (invertebrates, seabirds, elasmobranchs and teleost fish) in Otago's (New Zealand) coastal marine ecosystem. We identified which transmission routes are utilized by the most parasite species and assessed which intermediate hosts are most important in facilitating the transmission of parasites in this ecosystem. Our findings reveal 59 new records of larval parasites infecting their respective intermediate hosts and 289 transmission pathways utilized by 35 helminth species to complete their life cycles. Sprat, triplefin and arrow squid all hosted the highest number of larval parasite species, suggesting they play important roles as intermediate hosts. We then used the new life cycle data to provide a synthetic overview of the life cycles known for various parasite groups in New Zealand. This study highlights how studying parasite life cycles can enhance our understanding of the ecology and evolution of parasites and hosts in natural systems, beyond simply resolving life cycles. [ABSTRACT FROM AUTHOR]

Parasite avoidance is increasingly considered to be a potential driving factor in animal migrations. In many marine and freshwater benthic fish, migration into a pelagic environment by developing larvae is a common life history trait that could reduce exposure to parasites during a critical window of developmental susceptibility. We tested this hypothesis on congeneric fish (family Galaxiidae, genus Galaxias) belonging to a closely related species complex sampled from coastal streams in southeastern New Zealand. Migratory Galaxias have larvae that migrate to pelagic marine environments, whereas the larvae of non-migratory species rear close to adult habitats with no pelagic larval phase. Both migratory and non-migratory fish are hosts to two species of skin-penetrating trematodes that cause spinal malformations and high mortality in young fish. Using generalized linear models within an Akaike information criterion and model averaging framework, we compared infection levels between migratory and non-migratory fish while taking into account body size and several other local factors likely to influence infection levels. For one trematode species, we found a significant effect of migration: for any given body length, migratory fish harboured fewer parasites than non-migratory fish. Also, no parasites of any kind were found in juvenile migratory fish sampled in spring shortly after their return to stream habitats. Our results demonstrate that migration spares juvenile fish from the debilitating parasites to which they would be exposed in adult stream habitats. Therefore, either the historical adoption of a migratory strategy in some Galaxias was an adaptation against parasitism, or it evolved for other reasons and now provides protection from infection as a coincidental side-effect. [ABSTRACT FROM AUTHOR]

While parasites are likely to encounter several potential intermediate hosts in natural communities, a parasite's actual range of compatible hosts is limited by numerous biological factors ranging from behaviour to immunology. In crustaceans, two major components of immunity are haemocytes and the prophenoloxidase system involved in the melanisation of foreign particles. Here, we analysed metazoan parasite prevalence and loads in the two sympatric crab species Hemigrapsus crenulatus and Macrophthalmus hirtipes at two sites. In parallel, we analysed the variation in haemocyte concentration and amount of circulating phenoloxidase (PO) in the haemolymph of the same individuals in an attempt to (a) explain differences in parasite prevalence and loads in the two species at two sites and (b) assess the impact of parasites on these immune parameters. M. hirtipes harboured more parasites but also exhibited higher haemocyte concentrations than H. crenulatus independent of the study site. Thus, higher investment in haemocyte production for M. hirtipes does not seem to result in higher resistance to parasites. Analyses of variation in immune parameters for the two crab species between the two sites that differed in parasite prevalence showed common trends. (a) In general, haemocyte concentrations were higher at the site experiencing higher parasitic pressure while circulating PO activity was lower and (b) haemocyte concentrations were influenced by microphallid trematode metacercariae in individuals from the site with higher parasitic pressure. We suggest that the higher haemocyte concentrations observed in both crab species exposed to higher parasitic pressure may represent an adaptive response to the impact of parasites on this immune parameter. [ABSTRACT FROM AUTHOR]

1. Animal malformations engender wide public and scientific concern because of associated environmental health risks. This is highlighted by increased incidence of limb malformations in amphibians associated with trematode infections and disturbance. Malformations may signal new emerging disease threats, but whether the phenomenon is broadly applicable across taxa, or has population-scale impacts, is unknown. 2. Malformations are widely reported in fish and, until now, have been attributed mainly to contaminants. We tested whether the trematode Telogaster opisthorchis caused severe malformations, leading to population effects, in Galaxias anomalus, a threatened New Zealand freshwater fish. 3. Experimental infection of larval fish caused increasing spinal malformation and mortality with infection intensity that closely matched field patterns. Field malformation frequency peaked in January (65%), before declining sharply in February (25%) and remaining low thereafter. 4. The peak occurred during a ‘critical window’ of larval development, with the decline coincident with a population crash, indicating that malformation was causing mortality in the field. 5. The occurrence of such critical developmental windows may explain why this mechanism of population impact has been overlooked. With global environmental stressors predicted to enhance trematode infections, our results show that parasite-induced malformation, and its population-scale impacts, could be more widespread than previously considered. [ABSTRACT FROM AUTHOR]

The comparative genetic structure of hosts and their parasites has important implications for their coevolution, but has been investigated in relatively few systems. In this study, we analysed the genetic structure and diversity of the New Zealand intertidal snail Zeacumantus subcarinatus ( n = 330) and two of its trematode parasites, Maritrema novaezealandensis ( n = 269) and Philophthalmus sp. ( n = 246), using cytochrome c oxidase subunit I gene ( COI) sequences. Snails and trematodes were examined from 11 collection sites representing three regions on the South Island of New Zealand. Zeacumantus subcarinatus displayed low genetic diversity per geographic locality, strong genetic structure following an isolation by distance pattern, and low migration rates at the scale of the study. In contrast, M. novaezealandensis possessed high genetic diversity, genetic homogeneity among collection sites and high migration rates. Genetic diversity and migration rates were typically lower for Philophthalmus sp. compared to M. novaezealandensis and it displayed weak to moderate genetic structure. The observed patterns likely result from the limited dispersal ability of the direct developing snail and the utilization of bird definitive hosts by the trematodes. In addition, snails may occasionally experience long-distance dispersal. Discrepancies between trematode species may result from differences in their effective population sizes and/or life history traits. [ABSTRACT FROM AUTHOR]

1. It is well recognised that non-indigenous species (NIS) can affect native communities via the ‘spillover’ of introduced parasites. However, two other potentially important processes, the ‘spillback’ of native parasites from a competent NIS host, where the latter acts as a reservoir leading to amplified infection in native hosts, and the ‘dilution’ of parasitism by a NIS host acting as a sink for native parasites, have either not been tested or largely overlooked. 2. We surveyed the helminth parasite fauna of native New Zealand fish in Otago streams that varied in the abundance of introduced brown trout Salmo trutta, to look for evidence of spillback and/or dilution. Spillover is not an issue in this system, with trout introduced as parasite-free eggs. 3. Seven native parasite species were present across 12 sites; significant inverse relationships with an index of trout abundance (i.e. dilution) were documented for three species infecting the native upland bully Gobiomorphus breviceps, and one species infecting the native roundhead galaxias Galaxias anomalus. 4. An inverse relationship between bully energy status and infection intensity of one parasite species suggests that parasite dilution could have positive effects on bully populations. Our failure to detect similar relationships for the other parasites does not preclude the possibility that dilution is beneficial to native fish, since parasites may have subtle or unmeasured impacts. 5. The parasite dilution patterns reported are compelling in that they occurred across several native host and parasite species; as such they have important implications for invasion ecology, providing an interesting contrast to the largely negative impacts reported for NIS. Mechanisms potentially responsible for the patterns observed are discussed. [ABSTRACT FROM AUTHOR]

Given the importance of temperature for the shedding of trematode infective stages (cercariae) from gastropod first intermediate hosts, we investigated the response to temperature increases of trematodes of the intertidal snail Zeacumantus subcarinatus collected from different latitudes (differing in mean annual summer temperature) on the South Island of New Zealand. We investigated whether shedding of cercariae at elevated temperatures differed both between species (interspecific variation) and among populations of each trematode species (intraspecific variation). The shedding of one trematode species, Maritrema novaezealandensis (Microphallidae), appears to decrease with increased temperature and differed among locations. In contrast, the shedding of a second species, Acanthoparyphium sp. (Echinostomatidae), increased at warmer temperatures. In particular, Acanthoparyphium sp.-infected snails from 1 location showed the greatest increase in the shedding of cercariae in response to elevated temperature. Our results demonstrate that different trematode species and populations may be dissimilarly impacted by temperature changes resulting from global warming. In addition, both interspecific and intraspecific variation may result in different impacts of trematodes on ecosystems at different locales. [ABSTRACT FROM AUTHOR]

Abstract: Larval helminths often share intermediate hosts with other individuals of the same or different species. Competition for resources and/or conflicts over transmission routes are likely to influence both the association patterns between species and the life history strategies of each individual. Parasites sharing common intermediate hosts may have evolved ways to avoid or associate with other species depending on their definitive host. If not, individual parasites could develop alternative life history strategies in response to association with particular species. Three sympatric species of helminths exploit the amphipod Paracalliope fluviatilis as an intermediate host in New Zealand: the acanthocephalan Acanthocephalus galaxii, the trematode Microphallus sp. and the progenetic trematode Coitocaecum parvum. Adult A. galaxii and C. parvum are both fish parasites whereas Microphallus sp. infects birds. We found no association, either positive or negative, among the three parasite species. The effects of intra- and interspecific interactions were also measured in the trematode C. parvum. Both intra- and interspecific competition seemed to affect both the life history strategy and the size and fecundity of C. parvum. Firstly, the proportion of progenesis was higher in metacercariae sharing their host with Microphallus sp., the bird parasite, than in any other situation. Second, the intensity of intraspecific competition apparently constrained the ability of metacercariae to adopt progenesis and limited both the growth and egg production of progenetic individuals. These results show that the life history strategy adopted by a parasite may be influenced by other parasites sharing the same host. [Copyright &y& Elsevier]

The article presents a study to determine the prevalence and effects of infection with copepods and pea crabs on three mussel species at Bucklands Beach, Auckland, New Zealand. The mussel species in this study included the non-native Musculista senhousia, and two native mussels, Perna canaliculus and Xenostrobus pulex. It is noted that copepod prevalence was highest in X. pulex, while pea crab prevalence was highest in P. canaliculus. Copepods and pea crabs infected M. senhousia at a much lower prevalence. Moreover, it is inferred that infections of M. senhousia were chance encounters of the pea crabs with the introduced species rather than an active selection in response to cues from the host.

The cercariae and sporocysts (or rediae) of four trematode species are described from the intertidal snail Zeacumantus subcarinatus: a distome xiphidiocercaria assigned to the genus Renicola (family Renicolidae); a monostome xiphidiocercaria belonging either to the genus Microphallus or Megalophallus (family Microphallidae); a magnacercous cercaria of the genus Galactosomum (family Heterophyidae); and a cercaria of the genus Philophthalmus (family Philophthalmidae). The morphological features of these cercariae are compared to previously described cercariae of the same genera. in addition, since the philophthalmid cercaria encysts readily on artificial substrates in the laboratory, the metacercaria of this species is also described. These cercariae are part of a diverse community of at least six digenean species parasitising the snail Z. subcarinatus that, together, have a major impact on the ecology and evolution of this snail. [ABSTRACT FROM AUTHOR]

Sand hoppers (Amphipoda: Talitridae) are semiterrestrial crustaceans that feed upon stranded kelp. Their burrowing behaviour plays an important role in reintroducing nutrients into the sediment. The most abundant sand hopper on New Zealand’s beaches is Talorchestia quoyana Milne-Edwards, 1840. It is host to a parasitic mermithid nematode, Thaumamermis zealandica Poinar, Latham and Poulin, 2002, which invariably kills its sand hopper host by emerging to complete its maturation and reproduction in a moist sand environment. The aim of the present study was to assess if the burrowing behaviour of Ta. quoyana showed pathologic consequences of infection by Th. zealandica. Two experiments were conducted to assess temporal variation in sand hopper burrowing in vitro. Parameters measured included the hour after sunrise and sunset that sand hoppers first emerged and the number of surface visits in the first hour after emergence. Across experiments, sand hopper burrowing behaviour showed considerable heterogeneity related to sand hopper length, sand hopper distribution, experimental series, and experimental moisture conditions. The presence of parasites was not a significant factor in determining sand hopper burrowing behaviour. The lack of pathological effect is surprising given the relative size of Th. zealandica. [ABSTRACT FROM AUTHOR]

Abstract: A new 23-collar-spined cercaria and metacercaria are described from intertidal molluscs of the coast of New Zealand. The new cercaria found emerging from the mud snails Zeacumantus subcarinatus (Sowerby) (Prosobranchia: Batillariidae) is characterized mainly by the number and arrangement of the cephalic glands, the size of the suckers, and the size and number of the collar spines. The cercaria encysts in the cockle Austrovenus stutchburyi (Wood) (Bivalvia: Veneridae) which lives in sympatry with the first intermediate host throughout New Zealand. Laboratory infections of cockles by cercariae from naturally infected snails resulted in metacercariae identical to those found in naturally infected cockles. The main features of the cercaria and metacercaria are the presence of a reniform collar with 23 spines, two pairs of small cephalic glands at the oral sucker level, another two pairs of much longer ones posterior to the pharynx, and the excretory vesicle Y-shaped with the main collecting canals extending to the anterior level of the ventral sucker. Each of the main collecting canals had 10–11 pairs of bilateral diverticula between the anterior edge of the ventral sucker and anterior body end. A brief discussion of its possible life cycle and ecology is also provided. [Copyright &y& Elsevier]

The article presents a study on the macroparasite and ectosymbiont fauna of the introduced portunid crab Charybdis japonica and its comparison with sympatric and allopatric populations of the native portunid, Ovalipes catharus in New Zealand. It discusses the collection of 468 crabs from six harbours of the country and presents the comparison on the identity, incidence and prevalence of ectosymbionts and parasites among the different populations.

Zonation of organisms in soft-bottom intertidal habitats is mainly a consequence of the tidal sorting of the substrate and how benthic organisms respond to it, with predation and competition also playing a role. Although parasites are ubiquitous in these habitats and known agents of community structure, their impact on zonation is rarely considered. Here, using observational and experimental data, we show that parasitism of the cockle Austrovenus stutchburyi by echinostome trematodes has both direct and indirect effects on the zonation of four other animals associated with cockles on a New Zealand tidal flat. The trematodes encyst in the foot of cockles, leaving heavily infected cockles unable to bury and lying exposed on the sediment surface. Whereas cockle density peaks in the mid intertidal zone, both infection intensity by trematodes and density of surfaced cockles increase linearly towards the shore; this influences the vertical zonation of animals attaching to or feeding on cockles. First, the relative abundance of the whelk Cominella glandiformis increase exponentially shoreward, as does its rate of predation on cockles; the effect of the parasite on the cockles’ burying ability has thus shifted the peak abundance of whelk predators towards the upper tidal level, away from peak cockle densities. Second, the density of the anemone Anthopleura aureoradiata, corrected for the availability of its cockle substrate, peaks in the lower intertidal zone, although a transplantation experiment revealed that anemones can survive higher up the shore if attached to buried cockles. Anemones on exposed cockles are susceptible to desiccation, and thus again the parasite-induced surfacing of cockles at higher tidal levels plays a role by decreasing substrate availability for anemones. Third, densities of the limpet Notoacmea helmsi increase rapidly toward higher tidal levels, where limpets graze the surfaces of empty cockle shells or live surfaced cockles. The availability of both substrates used by limpets is influenced either directly (surfaced cockles) or indirectly (empty shells, via whelk predation) by parasitism. Fourth, the fish Notolabrus celidotus feeds on cockles by cropping their foot. Although the lower intertidal is submerged for longer and cockle densities peak in the mid intertidal, the frequency of foot-cropping by fish peaks in the upper tidal levels, where parasitism maintains a high density of surfaced cockles. Our results are the first demonstration that parasitism of a key species can influence the zonation of non-host organisms, a phenomenon likely to occur in other systems. [ABSTRACT FROM AUTHOR]

Estimates of total parasite species richness, for given host groups in given geographical areas, are always much higher than the numbers of known parasite species on which they are based. The discrepancy is a reflection of our limited current knowledge of parasite diversity. This is illustrated by a comparison of the parasite faunas of New Zealand fish species with those of Canadian fish; the latter have been well studied by fish parasitologists, and provide a standard for comparisons. More parasite species are known per host species for Canadian fish than for New Zealand fish, for both marine and freshwater fishes. This difference remains after correcting for differences in study effort, i.e. in the number of published studies per fish species. There are also more parasite species per fish species in Canada than in New Zealand when parasite species richness is expressed as number of species per unit of host body length. For freshwater fish, the difference can be explained by the restricted phylogenetic origins and geographical isolation of New Zealand fish species. For marine fish, however, there is no a priori reason to expect a difference in parasite species richness between fish in New Zealand and Canadian waters, and the observed difference probably results from a lack of appropriate parasitological surveys in New Zealand. If the true species richness of the parasite faunas of New Zealand marine fish species approaches that of their Canadian counterparts, then most of the diversity and ecosystem function of fish parasites in New Zealand remains unknown. [ABSTRACT FROM AUTHOR]

The effects of the acanthocephalan parasites Profilicollis antarcticus and P. novaezelandensis on the fecundity and mortality of three species of shore crab (Macrophthalmus hirtipes, Hemigrapsus edwardsi and H. crenulatus) are examined. The number of eggs produced by female crabs was strongly correlated (all P < 0.05) with carapace width; parasite load was not a significant determinant of female fecundity. Mortality was inferred from reduction in the mean number of parasites per crab in the largest crab size-classes, indicating that heavily infected individuals are removed from the population. Mortality attributable to the parasites was observed for all three species of crabs, although the effect of parasites varied in both time and space; significant curvilinear regressions between parasite load and crab size-classes were not found in all samples. Crab mortality appears to be influenced by more than the pathological influences exerted by the parasites. Parasiteinduced behavioural alterations may cause crab hosts to be more susceptible to predation by definitive hosts. We support this suggestion with three lines of evidence: the lack of parasite effects on fecundity, the weakening of the parasite effect on mortality during the time of year when birds are absent, and previous indications of parasitemediated alterations in crab burrowing behaviour. [ABSTRACT FROM AUTHOR]

We describe nematomorph specimens from New Zealand and compare them to museum specimens of Gordius paranensisCamerano, 1892 from Chile. Although specimens from New Zealand and Chile vary from each other, especially in body dimensions and coloration, literature data on other South American specimens of G. paranensiscorrespond to the New Zealand specimens which are therefore considered to belong to this species. A conspicuous character of G. paranensisis a precloacal, parabolic row of bristles that has been observed elsewhere only in G. difficilis(Montgomery, 1898). [ABSTRACT FROM AUTHOR]

Examines the helminth parasites of birds in New Zealand. Relationship between local abundance and distribution; Analysis of host specificity; Colonization of host species.

Ten polymorphic loci were isolated and characterized from the intertidal New Zealand trematode Gymnophallus sp., a common parasite of the abundant local bivalve Austrovenus stutchburyi. Observed heterozygosities ranged from 0.17 to 0.96, and three to 23 alleles were detected in 24 trematode metacercariae. These loci are currently being used to investigate the molecular ecology of this species within the bivalve host. [ABSTRACT FROM AUTHOR]

Endosymbionts and intracellular parasites are common in arthropod hosts. As a consequence, (co)amplification of untargeted bacterial sequences has been occasionally reported as a common problem in DNA barcoding. While identifying amphipod species with universal COI primers, we unexpectedly detected rickettsial endosymbionts belonging to the Torix group. To map the distribution and diversity of Rickettsia species among amphipod hosts, we conducted a nationwide molecular screening of seven families of New Zealand freshwater amphipods. In addition to uncovering a diversity of Torix Rickettsia species across multiple amphipod populations from three different families, our research indicates that: (1) detecting Torix Rickettsia with universal primers is not uncommon, (2) obtaining 'Rickettsia COI sequences' from many host individuals is highly likely when a population is infected, and (3) obtaining 'host COI' may not be possible with a conventional PCR if an individual is infected. Because Rickettsia COI is highly conserved across diverse host taxa, we were able to design blocking primers that can be used in a wide range of host species infected with Torix Rickettsia. We propose the use of blocking primers to circumvent problems caused by unwanted amplification of Rickettsia and to obtain targeted host COI sequences for DNA barcoding, population genetics, and phylogeographic studies. [ABSTRACT FROM AUTHOR]