Ecophysiological responses of juvenile summer and winter flounder to hypoxia: experimental and modeling analyses of effects on estuarine nursery quality
Date
2006-11-07
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Inter-Research
Abstract
Growth and feeding rates were measured in juvenile summer flounder Paralichthys
dentatus and winter flounder Pseudopleuronectes americanus exposed to sub-lethal hypoxia (low
dissolved oxygen, DO) over a range of temperatures, to determine its potential effects on nursery
habitat quality for these 2 estuary-dependent flatfishes. Growth rates of both species were generally
reduced as DO decreased, particularly at DO levels of 50 to 70% air saturation, and as temperature
increased. Summer flounder were more tolerant of low DO than were winter flounder at both 20 and
25°C. At these temperatures, summer flounder growth was reduced by ~25% (compared to growth
at normoxia [7.0 mg O2 l–1]) at 3.5 mg O2 l–1 and by 50 to 60% at 2.0 mg O2 l–1. In contrast, growth
of winter flounder at 20°C was reduced by ~50% at both 3.5 and 5.0 mg O2 l–1, and growth was
zero at 2.0 mg O2 l–1. At 25°C, winter flounder grew poorly in all DO treatments and lost weight at
2.0 mg O2 l–1. Summer flounder were also tested at 30°C. Growth was significantly reduced even at
5.0 mg O2 l–1, and was reduced by ~90% at 2.0 mg O2 l–1. A significant relationship between feeding
rate and growth suggested reduced consumption to be a major cause of growth limitation under
hypoxia. There was no evidence of growth acclimation for either species after 7 to 14 d exposure to
hypoxia. The effect of hypoxia on growth of summer flounder was reduced at lower salinity (15 vs.
25‰) and was unaffected by the presence of a sand substrate. Similarity between modeled growth
under hypoxic conditions, based on our laboratory results, and observed growth of summer flounder
in a hypoxic estuarine tributary suggests growth limitation in the wild. These laboratory and field
results demonstrate that even moderate hypoxia can adversely affect growth rates, and thus the
quality of estuarine nursery habitats for juvenile flatfishes.
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Citation
Stierhoff, Kevin L., Timothy E. Targett, and KerriLynn Miller. "Ecophysiological responses of juvenile summer and winter flounder to hypoxia: experimental and modeling analyses of effects on estuarine nursery quality." Marine Ecology Progress Series 325 (2006): 255-266.