Paracorophium Excavatum Research Articles

Temperature and multiple parasites combine to alter host community structure

Predicting the effects of climate change requires understanding complex interactions among multiple abiotic and biotic factors. By influencing key interactions among host species, parasites can affect community and ecosystem structuring. Yet, our understanding of how multiple parasites and abiotic factors interact to alter ecosystem structure remains limited. To empirically test the role of temperature variation and parasites in shaping communities, we used a multigenerational mesocosm experiment composed of four sympatric freshwater crustacean species (isopods and amphipods) that share up to four parasite species. Mesocosms were assigned to one of four different treatments with contrasting seasonal temperatures (normal and elevated) and parasite exposure levels (continuous and arrested (presence or absence of parasite larvae in mesocosm)). We found that parasite exposure and water temperature had interactive effects on the host community. Continuous exposure to parasites altered the community structure and differences in water temperature altered species abundance. The abundance of the amphipod Paracalliope fluviatilis decreased substantially when experiencing continuous parasite exposure and elevated water temperatures. Elevated temperatures also led to parasite‐induced mortality in another amphipod host, Paracorophium excavatum. Contrastingly, isopod hosts were affected much less, suggesting increasing temperatures in conjunction with higher parasite exposure might increase their relative abundance in the community. Changes in invertebrate host populations have implications for other species such as fish and birds that consume crustaceans as well as having impacts on ecosystem processes, such as aquatic primary production and nutrient cycling. In light of climate change predictions, parasite exposure and rise in average temperatures may have substantial impacts on communities and ecosystems, altering ecosystem structure and dynamics.

Differential impacts of shared parasites on fitness components among competing hosts.

Effects of parasites on individual hosts can eventually translate to impacts on host communities. In particular, parasitism can differentially affect host fitness among sympatric and interacting host species. We examined whether the impact of shared parasites varied among host species within the same community. Specifically, we looked at the impacts of the acanthocephalan Acanthocephalus galaxii, the trematodes Coitocaecum parvum and Maritrema poulini, and the nematode Hedruris spinigera, on three host species: the amphipods, Paracalliope fluviatilis and Paracorophium excavatum, and the isopod, Austridotea annectens. We assessed parasite infection levels in the three host species and tested for effects on host survival, behavior, probability of pairing, and fecundity. Maritrema poulini and C. parvum were most abundant in P. excavatum but had no effect on its survival, whereas they negatively affected the survival of P. fluviatilis, the other amphipod. Female amphipods carrying young had higher M. poulini and C. parvum abundance than those without, yet the number of young carried was not linked to parasite abundance. Behavior of the isopod A. annectens was affected by M. poulini infection; more heavily infected individuals were more active. Paracorophium excavatum moved longer distances when abundance of C. parvum was lower, yet no relationship existed with respect to infection by both M. poulini and C. parvum. The differential effects of parasites on amphipods and isopods may lead to community‐wide effects. Understanding the consequences of parasitic infection and differences among host species is key to gaining greater insight into the role of parasite mediation in ecosystem dynamics.

Do parasites adopt different strategies in different intermediate hosts? Host size, not host species, influencesCoitocaecum parvum(Trematoda) life history strategy, size and egg production

Host exploitation induces host defence responses and competition between parasites, resulting in individual parasites facing highly variable environments. Alternative life strategies may thus be expressed in context-dependent ways, depending on which host species is used and intra-host competition between parasites. Coitocaecum parvum (Trematode) can use facultative progenesis in amphipod intermediate hosts, Paracalliope fluviatilis, to abbreviate its life cycle in response to such environmental factors. Coitocaecum parvum also uses another amphipod host, Paracorophium excavatum, a species widely different in size and ecology from P. fluviatilis. In this study, parasite infection levels and strategies in the two amphipod species were compared to determine whether the adoption of progenesis by C. parvum varied between these two hosts. Potential differences in size and/or egg production between C. parvum individuals according to amphipod host species were also investigated. Results show that C. parvum life strategy was not influenced by host species. In contrast, host size significantly affected C. parvum strategy, size and egg production. Since intra-host interactions between co-infecting parasites also influenced C. parvum strategy, size and fecundity, it is highly likely that within-host resource limitations affect C. parvum life strategy and overall fitness regardless of host species.

The role of vicariance and dispersal on New Zealand's estuarine biodiversity: the case of Paracorophium (Crustacea: Amphipoda)

To investigate the role of vicariance and dispersal on New Zealand’s estuarine biodiversity, we examined variability in mitochondrial cytochrome c oxidase subunit I (COI) gene sequences for the amphipod genus Paracorophium. Individuals from the two nominate endemic species (Paracorophium excavatum and Paracorophium lucasi) were collected from sites throughout the North and South Islands. Sequence divergences of 12.8% were detected among the species. However, divergences of up to 11.7% were also observed between well supported clades, suggesting the possibility of cryptic species. Nested clade analyses identified four distinct lineages from within both P. excavatum and P. lucasi, with boundaries between clades corresponding to topographical features (e.g. Cook Straight, North and East Cape). Sequence divergences of 3.7–4.9% were also observed within geographic regions (e.g. east and west coasts of the upper North Island). Genetic structure in Paracorophium appears to represent prolonged isolation and allopatric evolutionary processes dating back to the Upper Miocene and continuing through the Pliocene and early Pleistocene. On the basis of molecular clock estimates from sequence divergences and reconstructions of New Zealand’s geological past, we suggest that sea level and landmass changes during the early Pleistocene (2 Mya) resulted in the isolation of previously contiguous populations leading to the present-day patterns. COI genetic structure was largely congruent with previously observed allozyme patterns and highlights the utility of COI as an appropriate marker for phylogeographic studies of the New Zealand estuarine fauna. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103, 863–874.

New evidence on a cold case: trophic transmission, distribution and host-specificity in Hedruris spinigera (Nematoda: Hedruridae)

The life cycle of Hedruris spinigera Baylis, 1931 (Nematoda: Hedruridae) is determined here with the first formal identification of the parasite's intermediate host: the crustacean amphipod Paracorophium excavatum Thomson. Adult H. spinigera are redescribed from specimens collected from the stomach of fishes, Retropinna retropinna (Richardson) and Aldrichettaforsteri (Valenciennes), from Lake Waihola, New Zealand. Immature adults of the parasite collected from intermediate hosts (P. excavatum) are also described for the first time. The prevalence, abundance and intensity of infection of H. spinigera in several fish species are quantified along with the occurrence of P. excavatum, the parasite's intermediate host, in fish stomach contents. Although H. spinigera's transmission mode (trophic transmission) and fish diet potentially expose all fish species to infection, some level of host specificity must exist as parasite prevalence, abundance and intensity of infection vary greatly between potential definitive host species. We suggest here that the anatomy of the fish digestive tract and especially that of the stomach plays an important role in host suitability for H. spinigera. While P. excavatum is the only intermediate host in Lake Waihola, H. spinigera was found in six different fish species: Aldrichetta forsteri, Galaxias maculatus (Jenyns), Retropinna retropinna, Rhombosolea retiaria Hutton, Perca fluviatilis Linnaeus and Salmo trutta Linnaeus; although typical hedrurid attachment and mating positions were observed only in R. retropinna and A. forsteri. The limited distribution of H. spinigera is most likely due to that of its different host species (intermediate and definitive), all inhabitants of coastal fresh and brackish waters.

Larval Hysterothylacium sp. (Nematoda, Anisakidae) and trematode metacercariae from the amphipod Paracorophium excavatum (Corphiidae) in New Zealand

AbstractPreviously undescribed fourth-stage larvae of anisakid nematodes were found in the haemocoel of the amphipod Paracorophium excavatum (Thomson, 1884) (Corophiidae) in New Zealand. Morphological examination by light microscopy showed that the worms belonged to a species of Hysterothylacium Ward et Magath, 1917, based on several characters including the presence of interlabia, the location of the excretory pore posterior to the nerve ring, and the characteristics of the intestinal caecum and ventricular appendix. Interestingly, several male specimens showed precocious sexual development. This is the first record of fourth larval stage and precocious adult male specimens of Hysterothylacium in an invertebrate host, as well as the first record of anisakid larvae in New Zealand crustaceans. In addition, metacercariae of two trematode species, Coitocaecum parvum and Microphallus sp., are recorded for the first time from the amphipod P. excavatum.

Australasian species of Paracorophium (Crustacea: Amphipoda): The separate identities of P. excavatum (Thomson, 1884) and P. brisbanensis sp. nov

Paracorophium excavatum (Thomson, 1884) is redescribed from the type locality, and distribution records in New Zealand are amplified. A previously unrecognised species, P. brisbanensis sp. nov., is described from Queensland, Australia. Earlier taxonomists confused the two species and used a mixture of their characteristics in their incorrect descriptions of P. excavatum.

Life-history traits of a tube-dwelling corophioid amphipod, Paracorophium excavatum, exposed to sediment copper

This is the first demonstration that sediment contaminants can influence the reproduction of amphipods. Groups of Paracorophium excavatum from a slightly contaminated estuarine site were held within laboratory mesocosms containing four copper-spiked estuarine sediments (Cu 14–46 μg g −1 dry weight) and a control sediment (Cu 5 μg g −1 dry weight) at 15 °C for 28 days. Copper sediment concentration did not affect the amphipod sex ratio. Female maturation was inhibited within copper-spiked sediments but female length was similar. Juvenile recruitment occurred only in sediments containing less than 20 μg g −1. Males were significantly larger than females in the control sediment (Cu 5 μg g −1 dry weight) and male length decreased linearly with increasing copper concentration. The copper concentration within whole body tissues increased with dry body dry weight in all sediments except the highest copper concentration. Following 28 days of exposure, none of the female amphipods from the copper-dosed sediments was brooding embryos. In contrast, brood size of females in the control sediment (Cu 5 μg g −1) was similar to field samples. Because low concentrations of sediment copper affect the maturation and growth rates of male and female amphipods differently, these life-history traits could affect the population structure of amphipods exposed to copper contaminated sediments.

The Interacting Effect of Hydrodynamics and Organic Matter on Colonization: a Soft-Sediment Example

This study examined whether buried organic matter in the form of seagrass influenced colonization by the corophiid amphipod Paracorophium excavatum in an intertidal sandflat. Laboratory manipulations were compared to results from field studies to determine the role of hydrodynamics in mediating the effects of the organic matter. At levels of organic loading greater than 1% of sediment dry weight, size frequency effects and decreases in numbers of colonizers occurred in still water conditions. In the field, however, at levels of organics up to ∼2% of sediment dry weight, only size-frequency effects were observed. A change in hydrodynamic conditions and the influence of this on sediment geochemistry is suggested as the most reasonable explanation for the disparity in colonization both between sites in the field and between laboratory and field manipulations. Two effects of organics upon corophiid amphipod colonization are proposed: a lower level of organic loading that can lead to a greater proportion of juveniles in the colonizing population and a higher level of organics that can lead to a decrease in the numbers of amphipods colonizing. The threshold at which these effects take place is modulated by the hydrodynamics of the environment. The same organic addition can therefore have different effects upon colonization across a tidal flat, which is dependent upon the variation in hydrodynamics

Effects of sediment copper on a tube-dwelling estuarine amphipod, Paracorophium excavatum

Amphipods, Paracorophium excavatum, were exposed for 10 days to copper-spiked sediments in the concentration range 3–84 µg g –1 dry wt of sediment. Percent emergence was low, ranging from 0.18% to 2.1%, but increased with exposure time and with copper concentration. Amphipod mortality increased with exposure time and sediment copper concentration, following a linear relationship; the Cu 10-day LC 50 value was 55 µg g –1 . Mortality was <5% in the control (natural) sediment containing 3µg g–1 copper. >85% of surviving amphipods reburied themselves within 1 h, and therefore this behaviour was not a good discriminator for potentially toxic sediments. The concentration of copper within the whole-body tissues of P. excavatum (µg Cu g –1 ) was mostly independent of dry body weight within the range 0.12–0.37 mg. Average copper concentrations within the tissues ranged from 169 to 490 µg Cu g –1 , with higher variability in amphipods exposed to sediment copper concentrations of 16 and 32 µg g –1 . Amphipod tissue copper concentration increased with sediment copper concentration. It was concluded that P. excavatum is a suitable indicator species for use in ecotoxicological tests for potentially toxic marine and estuarine sediments.

Temporal and spatial variation in macrofauna community composition imposed by ghost shrimp Callianassa filholi bioturbation

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 192:249-257 (2000) - doi:10.3354/meps192249 Temporal and spatial variation in macrofauna community composition imposed by ghost shrimp Callianassa filholi bioturbation Katrin Berkenbusch1,*, Ashley A. Rowden2, P. Keith Probert1 1Department of Marine Science, University of Otago, PO Box 56, Dunedin, New Zealand 2Benthic Ecology Research Group, Department of Biological Sciences, University of Plymouth, Drake Circus, Plymouth, Devon PL 8AA, United Kingdom *E-mail: katrin.berkenbusch@stonebow.otago.ac.nz ABSTRACT: The impact of bioturbation by the burrowing ghost shrimp Callianassa filholi on benthic community composition was examined in relation to seasonal and small-scale spatial changes. Sites of naturally occurring low and high densities of C. filholi on an intertidal sandflat represented differences in bioturbation activity throughout the year. Univariate and multivariate analyses showed significant differences in community composition between high- and low-density sites. The total number of species and total number of individuals were lower at high-density sites. A corophiid amphipod, Paracorophium excavatum and a small bivalve, Perrierina turneri, appeared to have the greatest discriminating significance with lower abundances of both species at sites of high C. filholi density. Even though differences between sites of different density persisted throughout the year, the impact of bioturbation depended on season. Bioturbation had the highest maximum correlation to changes in macrofaunal community composition in winter, spring and, in association with seagrass biomass (Zostera novazelandica), in autumn. During summer, however, seagrass biomass contributed the most to observed differences and appeared to compensate for generally high bioturbation activity. The results imply that bioturbation impacted on macrofauna community composition over a small spatial scale and, although its impact varied seasonally, imposed patterns persisted throughout the year. As such, C. filholi can be considered a keystone species. KEY WORDS: Macrofauna community · Bioturbation · Callianassa · Intertidal sandflat · Small scale Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 192. Publication date: January 31, 2000 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 2000 Inter-Research.

Macrobenthic colonisation of disturbances on an intertidal sandflat:the influence of season and buried algae

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 191:163-174 (1999) - doi:10.3354/meps191163 Macrobenthic colonisation of disturbances on an intertidal sandflat: the influence of season and buried algae R. B. Ford1,*, S. F. Thrush2, P. K. Probert1 1Department of Marine Science, University of Otago, PO Box 56, Dunedin, New Zealand 2National Institute of Water and Atmospheric Research Ltd, PO Box 11-115, Hamilton, New Zealand *E-mail: rbf@st-and.ac.uk ABSTRACT: This study examines whether macrofaunal colonisation differs seasonally in an intertidal sandflat. Frozen cores were placed in the sandflat within each season and colonisation of these cores was followed for 50 d. This study shows a previously untested effect of buried algal mats on colonisation. A change in the sediment organic content can increase or decrease macrofaunal densities. Community colonisation rates of defaunated plugs were slower in winter compared to summer because of the higher numbers of rare macrofauna in winter. Community colonisation of plugs with algal additions were also dependent on the seasonally varying response of the corophiid amphipod Paracorophium excavatum, the most abundant species in this community. The strongest effect of the experiments was linked to critical densities of P. excavatum, irrespective of season. A mechanism for this linkage is suggested. This study also emphasises the importance of post-settlement movement as the mechanism by which most species on this sandflat colonised in either season. KEY WORDS: Intertidal sands · New Zealand · Buried algae · Colonisation · Community ecology · Paracorophium excavatum · Seasonal effects Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 191. Publication date: December 30, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

Acute toxicity of cadmium to two species of infaunal marine amphipods (tube-dwelling and burrowing) from New Zealand.

Chapman reviewed the range of species and different response levels used in sediment toxicity testing. He recommended that a battery of sediment bioassays incorporating different response criteria should be used in sediment toxicity evaluations as there is no single test which gives adequate assessment of sediment toxicity. However, one test which is becoming accepted as the {open_quotes}benchmark{close_quotes} technique, and which is now commonly included in any battery of tests, is the amphipod bioassay. This test was developed in North America and uses the phoxocephalid Rhepoxynius abronius. It has been subjected to rigorous interlaboratory evaluation and its sensitivity and usefulness has been demonstrated in a wide range of applications. Unfortunately, species import controls makes the use of existing test species (such as R. abronius) impractical for sediment toxicity testing in New Zealand. In view of the demonstrated sensitivity, reproducibility and value of the amphipod bioassay, we therefore initiated preliminary studies to assess the possibility of developing a test with a native New Zealand amphipod. Examination of intertidal sediments in several northern New Zealand estuaries has shown that the amphipods Proharpinia hurleyi, Paracorophium excavatum and Paracalliope novizealandiae can be found, at times, in large numbers (hundreds per square metre). The results ofmore » benthic studies in Auckland`s Manaukau Harbour also suggested that P. excavatum and P. hurleyi may be sensitive to pollution, as these species were noticeably absent from sites where there was measurable sediment contamination. Using the protocol of Swartz et al., we undertook to test the sensitivity and laboratory performance of two local amphipod species; the tube-dweller P. contrasting modes of existence may differ in their level of exposure to sediment contaminants and, therefore, show different toxic responses. 12 refs., 2 tabs.« less