Variability in Juvenile English Sole Condition Relative to Temperature and Trophic Dynamics Along an Oregon Estuarine Gradient

Abstract

Many benthic fish and invertebrates, including the flatfish English sole (Parophrys vetulus), utilize estuaries as nursery habitat during their juvenile life stage. Regions within an estuary differ with respect to salinity, temperature, oxygen, and organic inputs, highlighting the complexity of nursery habitat and the need to assess multiple habitats within a single estuary. To determine the effect of variable estuarine habitat on juvenile English sole, we examined morphometric and energetic (lipid) condition, fatty acids, and stable isotopes (13C and 15N) of wild-caught juveniles from upriver and downriver habitats within the Yaquina Bay, Oregon estuary. Downriver-caught fish exhibited higher energetic condition, which may be attributed to cooler temperatures and the marine-sourced carbon that typified that region’s food web. Conversely, individuals from the upriver habitat exhibited higher morphometric condition. This may be due in part to the warmer temperatures upriver that have been observed to promote growth and suppress lipid storage in other marine species. Our findings highlight the important but variable contribution of both upriver and downriver habitats to English sole early life history.