Variability in Fish Tissue Proximate Composition is Consistent with Indirect Effects of Hypoxia in Chesapeake Bay Tributaries
Virginia Institute of Marine Science
MARINE AND COASTAL FISHERIES
The spatial and temporal extent of summer hypoxia (dissolved oxygen [DO] concentration <= 2 mg/L) in Chesapeake Bay and its tributaries has been increasing for decades, consequently affecting fish distribution and abundance by shifting biomass to non-hypoxic habitats. Hypoxia in coastal waters impacts food web dynamics, thereby limiting ecosystem productivity and affecting regional fisheries. Additionally, laboratory studies of Atlantic Croakers Micropogonias undulatus have shown that hypoxia serves as an endocrine disruptor, reducing the production of the yolk precursor vitellogenin as well as affecting other biochemical pathways. Reproductive potential is therefore lower in hypoxia-exposed Atlantic Croakers than in fish that are taken from normoxic conditions. We examined field-caught Atlantic Croakers from three Chesapeake Bay tributaries with different DO levels to evaluate patterns in the lipid content of somatic and gonadal tissues. We found that somatic lipid content was not affected by the presence of hypoxia, whereas ovarian lipid content was significantly affected by the severity of hypoxia. Furthermore, Atlantic Croakers that were exposed indirectly to mild hypoxia (lasting hours to days) exhibited greater ovarian lipid content than fish that were captured from normoxic sites. As expected, severe hypoxia reduced the ability of Atlantic Croakers to accumulate lipids in their ovaries, likely affecting reproductive output. Stock assessment models that ignore the effects of hypoxia may yield overly optimistic production estimates for hypoxia-exposed populations, particularly if environmentally invariant fecundity and growth are assumed.
CROAKER MICROPOGONIAS-UNDULATUS; GULF-OF-MEXICO; ATLANTIC CROAKER; BODY-COMPOSITION; DEMERSAL FISHES; RIVER ESTUARY; BROWN SHRIMP; ENERGY; CONSEQUENCES; AVOIDANCE
We are grateful to Wendy Lowery, G. Hank Brooks, Aimee Comer, and Jennifer Greaney (Juvenile Fish Trawl Survey staff, Virginia Institute of Marine Science) for specimen collection and water quality data. Additionally, we thank Sarah Mahlandt, David Lewis, and Anya Voloshin (volunteers) for assistance with laboratory processing of tissue samples. Finally, we thank two anonymous reviewers whose comments greatly improved the manuscript. The present study was funded by the National Oceanic and Atmospheric Administration, Chesapeake Bay Office (Award Number NA10NMF4570452). This paper is Contribution 3505 of the Virginia Institute of Marine Science, College of William and Mary.
Tuckey, Troy D. and Fabrizio, Mary C., "Variability in Fish Tissue Proximate Composition is Consistent with Indirect Effects of Hypoxia in Chesapeake Bay Tributaries" (2016). VIMS Articles. 35.
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