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Marine Ecology Progress Series

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MEPS 650:63-80 (2020)  -  DOI: https://doi.org/10.3354/meps13396

Consequences of plume encounter on larval fish growth and condition in the Gulf of Mexico

Kelia E. Axler1,4,*, Su Sponaugle1, Frank Hernandez Jr.2, Carla Culpepper2, Robert K. Cowen3

1Department of Integrative Biology, Hatfield Marine Science Center, Oregon State University, Newport, OR 97365, USA
2Division of Coastal Sciences, Gulf Coast Research Laboratory, University of Southern Mississippi, Ocean Springs, MS 39564, USA
3Hatfield Marine Science Center, Oregon State University, Newport, OR 97365, USA
4Present address: Alaska Fisheries Science Center, National Oceanic and Atmospheric Administration, 7600 Sand Point Way, Seattle, WA 98115, USA
*Corresponding author:
Advance View was available online August 6, 2020

ABSTRACT: Freshwater input into nearshore continental shelf waters from coastal river-estuarine plumes can greatly alter the physical and trophic environments experienced by fish larvae. However, the biological consequences of plume encounter on larval fish survival remain equivocal, largely due to the extreme variability of these systems but also because traditional sampling techniques alone are too coarse to effectively characterize the dynamic biophysical environment at spatiotemporal scales relevant to individual larvae. Using a multidimensional approach, we simultaneously collected in situ imagery and net samples of larval fishes and zooplankton from the Mobile Bay plume (Alabama, USA) and ambient continental shelf waters during a high discharge event (8-11 April 2016). We measured the effects of plume encounter on growth and condition of larval striped anchovy Anchoa hepsetus and sand seatrout Cynoscion arenarius, 2 prominent nearshore species in the northern Gulf of Mexico. Size-frequency distributions of both species indicated that larger individuals were present in shelf waters but absent from plume waters. Otolith microstructure analysis revealed that recent growth of both focal species was significantly lower for plume-collected larvae during the last few days prior to capture. Furthermore, plume larvae were in poorer morphometric condition (skinnier at length) than their shelf counterparts, despite the fact that there were higher concentrations of zooplankton prey in plume water masses. Taken together, these results suggest that elevated prey concentrations do not necessarily translate to higher growth and condition. High turbulence and turbidity within the plume may physically inhibit the prey capture ability and feeding success of fish larvae.


KEY WORDS: Ichthyoplankton · Otolith microstructure analysis · Growth · Morphometric condition · Anchovy · Seatrout


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Cite this article as: Axler KE, Sponaugle S, Hernandez F Jr, Culpepper C, Cowen RK (2020) Consequences of plume encounter on larval fish growth and condition in the Gulf of Mexico. Mar Ecol Prog Ser 650:63-80. https://doi.org/10.3354/meps13396

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