Parasite communities indicate effects of cross-shelf distributions, but not mesoscale oceanographic features on northern California Current mid-trophic food web

Abstract

Mesoscale physical oceanographic features, such as jets and eddies, can influence the structure of marine ecosystems. We used trophically transmitted parasite communities of pelagic fishes in the northern California Current to examine effects of physical oceanographic features on pelagic ecosystem structure. We tested the hypotheses that (1) oceanographic features associated with a coastal promontory, Cape Blanco, Oregon (USA), produced a faunal break resulting in different pelagic ecosystems north and south of the cape, and that (2) the use of biological hotspots in the area by pelagic nekton is reflected in the trophic interactions of mid-and upper trophic level fishes. We recovered 19 taxa of trophically transmitted parasites from 10 common pelagic fish species caught between Newport, Oregon, and Crescent City, California. Nonmetric multidimensional scaling of parasite communities reflected a trophic structure among these fish species; results were similar to published diet studies. We found no evidence in the trophically transmitted parasites of spatial differences between the pelagic ecosystems north or south of Cape Blanco, or within versus outside of the biological hotspots. However, we found significant cross shelf differences in parasite communities. Therefore, Cape Blanco does not seem to be a strong faunal boundary, rather the strongest influence is cross-shelf transport associated with coastal upwelling.KEY WORDS: Marine parasites · Pelagic fish · Cape Blanco · Hotspot · Inshore−offshore Resale or republication not permitted without written consent of the publisher

Factors linked to interannual variation in the metazoan parasite communities of black skipjack, Euthynnus lineatus (Pisces: Scombridae)

“…During this climate event, surface temperature (30.2°C) and salinity (35.5 ppt) in Acapulco Bay were significantly higher than in other sampling years (Table ). Abnormal increases in sea surface temperature can decrease the productivity of food webs, affecting the parasite transmission processes of many trophically transmitted parasites due to population decreases in potential intermediate or final hosts (Lamb et al, ; Jacobson et al, ; Oliva et al, ). In Acapulco Bay slight changes in the temperature and salinity parameters can be enough to generate notable changes in copepod community species composition throughout the year (Rojas‐Herrera, Violante‐Gonzalez, Garcia‐Ibañez, Villerias‐Salinas, & Moreno‐Diaz, ).…”

“…One of the most ubiquitous patterns in parasite ecology is high variability in parasite infection levels between populations of the same host species (Bagee, Poulin, & Valtonen, ; Marcogliese, ). Changes in local environmental factors, whether physical, oceanographic, or chemical, can facilitate the establishment and proliferation of certain parasites over time (Bagee et al, ; Jacobson et al, ; Lamb et al, ; Oliva et al, ). Therefore, local fluctuations in surface temperature and salinity, as well as changes in the diet of fish over time, may explain interannual variations in the infection levels of N. euthynni , C. caballeroi , H. ventricosa , Sicuotrema sp., Rhadinorhynchus sp., Anisakis sp., and Spinitectus sp.…”

“…Large‐scale climate fluctuations such as El Niño–Southern Oscillation (ENSO: sea temperature warming phase) and La Niña (cooling phase) are known to affect many ecological processes, including transmission of many metazoan parasites (Alvitres, Chaname, Fupuy, Chambergo, & Cortez, ; Oliva, Barrios, Thatje, & Laudien, ). For example, trophically transmitted parasites have free‐living stages that hatch from eggs and are affected by the same oceanographic physical conditions (e.g., temperature, salinity, currents) that affect the larval stages of other marine organisms, including those of their hosts (Jacobson, Baldwin, & Reese, ; Lohmus & Bjorklund, ; Marcogliese, ). During the most recent El Niño event (2015–2016), sea surface temperature rose by +2.5°C for 6 months in tropical regions such as the Galapagos Islands in the South Pacific.…”

Where are the parasites in food webs?

“…Nowhere is the idea that the same hosts in different food webs have different parasites more scrutinized than in fisheries management, an area where food web ecology and parasitology are most closely coupled. In this arena, it is well-established that accurate measures in fish migration patterns and stock assessment can be based on using parasites as biological tags [25-28]. Even fish stocks that are spatially or temporally separated by relatively short distances or times, can be identified by their parasites [29-31].…”

Use of parasites to clarify residency and migration patterns of Pacific sardine (Sardinops sagax) in the California Current

“…Genetic identification of larval anisakids from a subset of Pacific sardine used in our study revealed a panmictic distribution of 3 populations of Anisakis spp., but these populations could not help inform stock structure or migration behavior of Pacific sardine in the CCS (Baldwin et al, 2011). The acanthocephalan Rhadinorhynchus trachuri, also longer-lived than the trematodes, is known to be a parasite of offshore fish species (George-Nascimento, 2000;Jacobson et al, 2012). Although less commonly recovered than the nematodes, it was recovered more often from the large Pacific sardine caught south of British Columbia.…”