Do infections with parasites and exposure to pollution affect susceptibility to predation in johnny darters (Etheostoma nigrum)?

Johnny darters (Etheostoma nigrum Rafinesque, 1820) were collected from five localities in the St. Lawrence River in southwestern Quebec to test the effects of natural parasite infections and exposure in situ to pollution on their antipredator behaviour. Three measures of antipredator behaviour were made: (1) capture time (i.e., the time taken to catch individual fish) was used as a proxy for the ability to evade predation, (2) capture order was the order in which fish kept in a single tank were taken from the tank, and (3) flight initiation distance was the distance at which the fish moved when approached by a model predator. Only capture time showed a significant correlation with parasitism or pollution status. A nonparametric permutational multivariate ANOVA showed that capture time was significantly correlated with capture location and the abundance of the brain-encysting trematode Ornithodiplostomum Dubois, 1936. Infection with Ornithodiplostomum sp. may have led to an increase in activity, which would be maladaptive for this cryptic, benthic fish under natural predation conditions. Pollution may have an indirect effect on predator susceptibility in johnny darters, by reducing the abundance of a behaviour-modifying parasite

Apophallus microsoma N. SP. from Chicks Infected with Metacercariae from Coho Salmon (Oncorhynchus kisutch ) and Review of the Taxonomy and Pathology of the Genus Apophallus (Heterophyidae)

Metacercariae of an unidentified species of Apophallus Luhe, 1909 are associated with overwinter mortality in coho salmon, Oncorhynchus kisutch (Walbaum, 1792), in the West Fork Smith River, Oregon. We infected chicks with these metacercariae in order to identify the species. The average size of adult worms was 197 x 57 μm, which was 2 to 11 times smaller than other described Apophallus species. Eggs were also smaller, but larger in proportion to body size, than in other species of Apophallus. Based on these morphological differences, we describe Apophallus microsoma n. sp. In addition, sequences from the cytochrome c oxidase 1 gene from Apophallus sp. cercariae collected in the study area, which are likely conspecific with experimentally cultivated A. microsoma, differ by >12% from those we obtained from Apophallus donicus (Skrjabin and Lindtrop, 1919) and from Apophallus brevis Ransom, 1920. The taxonomy and pathology of Apophallus species is reviewed.Keywords: Mortality, St. Lawrence River, Life cycle, Parasite, Perch Perca flavescens, Trematoda, Yellow perch, Brevis, Oregon, Nanophyetus salmincol

Fundulus as the premier teleost model in environmental biology : opportunities for new insights using genomics

Author Posting. © Elsevier B.V., 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Comparative Biochemistry and Physiology Part D: Genomics and Proteomics 2 (2007): 257-286, doi:10.1016/j.cbd.2007.09.001.A strong foundation of basic and applied research documents that the estuarine fish Fundulus heteroclitus and related species are unique laboratory and field models for understanding how individuals and populations interact with their environment. In this paper we summarize an extensive body of work examining the adaptive responses of Fundulus species to environmental conditions, and describe how this research has contributed importantly to our understanding of physiology, gene regulation, toxicology, and ecological and evolutionary genetics of teleosts and other vertebrates. These explorations have reached a critical juncture at which advancement is hindered by the lack of genomic resources for these species. We suggest that a more complete genomics toolbox for F. heteroclitus and related species will permit researchers to exploit the power of this model organism to rapidly advance our understanding of fundamental biological and pathological mechanisms among vertebrates, as well as ecological strategies and evolutionary processes common to all living organisms.This material is based on work supported by grants from the National Science Foundation DBI-0420504 (LJB), OCE 0308777 (DLC, RNW, BBR), BES-0553523 (AW), IBN 0236494 (BBR), IOB-0519579 (DHE), IOB-0543860 (DWT), FSML-0533189 (SC); National Institute of Health NIEHS P42-ES007381(GVC, MEH), P42-ES10356 (RTD), ES011588 (MFO); and NCRR P20 RR-016463 (DWT); Natural Sciences and Engineering Research Council of Canada Discovery (DLM, TDS, WSM) and Collaborative Research and Development Programs (DLM); NOAA/National Sea Grant NA86RG0052 (LJB), NA16RG2273 (SIK, MEH,GVC, JJS); Environmental Protection Agency U91620701 (WSB), R82902201(SC) and EPA’s Office of Research and Development (DEN)

Review of experimental and natural invertebrate hosts of sealworm (<i>Pseudoterranova decipiens</i>) and its distribution and abundance in macroinvertebrates in eastern Canada

Experimental and natural invertebrate intermediate hosts of sealworm (Pseudoterranova decipiens) as well as transmission experiments of sealworm from invertebrates to fish are reviewed and summarized. Experimental hosts include copepods, mysids, cumaceans, isopods, amphipods, decapods, annelids, and molluscs. Invertebrates collected from eastern Canada between 1989 and 1995 were checked for nematode infections by microscopic examination of dissected animals or enzymatic digestion of bulk samples. Third-stage larval sealworm were found in mysids (Neomysis americana, Mysis stenolepis) from Passamaquoddy Bay, the Bras d’Or Lakes, inshore Cape Breton, Sable Island and Sable Island Bank. Infected amphipods (Amphiporeia virginiana, Americorchestia megalophthalma, Gammarus spp.) were found only on Sable Island. Typical infection rates in macroinvertebrates were 1-4/1000. No sealworm infections were found in approximately 18,000 amphipods examined from Sable Island Bank, the site of the most heavily infected fishes in eastern Canada. In Wallace Lake, a brackish pond on Sable Island, infection rates were much higher in mysids than in amphipods. Estimates of rates of transmission of sealworm from invertebrates to fish were derived from infection levels in Wallace Lake and feeding experiments involving sticklebacks and invertebrate prey. It is concluded that mysids may be much more important than amphipods in transmitting sealworm to fish hosts

Diplostomiasis (Diplostomum spathaceum and related species)

This book chapter describes various aspects of diplostomiasis caused by Diplostomum spathaceum: diagnosis, epidemiology, life cycle, transmission, developmental stages, population dynamics, effects of climate change on parasite distribution, and disease control and prevention.peerReviewe

Enigmatic decline of a common fish parasite (Diplostomum spp.) in the St. Lawrence River: Evidence for a dilution effect induced by the invasive round goby

As they integrate into recipient food webs, invasive exotic species may influence the population dynamics of native parasites. Here we assess the potential impact of the Eurasian round goby (Neogobius melanostomus) on the abundance of eyeflukes of the genus Diplostomum, which are common parasites in fishes of the St. Lawrence River (Canada). Analyses of data collected over nearly two decades revealed that the infection levels in three native fish [spottail shiner (Notropis hudsonius), golden shiner (Notemigonus crysoleucas) yellow perch (Perca flavescens)] declined sharply throughout the St. Lawrence River after the introduction of the goby. At two sites where data were collected at regular time intervals, declines of Diplostomum spp. in spottail shiners occurred within two years of the goby's first recorded appearance, with prevalence dropping as much as 77–80% between pre-invasion and post-invasion periods. Furthermore, in localities where gobies remained scarce, infection in native species did not change significantly over time. Altogether, these observations suggest that gobies play a role in the eyefluke collapse. The decline in populations of the main definitive host (ring-billed gulls, Larus delawarensis) and changes in hydrology during periods of parasite recruitment were not strongly supported as alternate explanations for this phenomenon. Since other snail-transmitted trematodes with similar life cycles to Diplostomum spp. did not show the same decreasing pattern, we conclude that eyeflukes did not decline as a result of snail depletion due to goby predation. Rather, we suggest that gobies acted as decoys, diluting the infection. As Diplostomum spp. occurred at lower abundance in gobies than in native fish hosts, the replacement of native fish with exotic gobies in the diet of gulls might have played a part in reducing parasite transmission. In contrast to the typically negative impact of invasions, the goby-induced decline of this pathogen may have beneficial effects for native fishes. Keywords: Round goby, Neogobius melanostomus, Diplostomum, Eyefluke, Parasite dilution, Exotic species, Fish disease, St. Lawrence Rive