MEPS 343:251-262 (2007)  -  DOI: https://doi.org/10.3354/meps06864

Density-dependent growth and mortality in an estuary-dependent fish: an experimental approach with juvenile spot Leiostomus xanthurus

J. Kevin Craig1,5,*, James A. Rice2, Larry B. Crowder3, David A. Nadeau4

1Department of Zoology, Center for Marine Sciences and Technology, North Carolina State University, 303 College Circle, Morehead City, North Carolina 28557, USA
2Department of Zoology, North Carolina State University, Raleigh, North Carolina 27695-7617, USA
3Nicholas School of the Environment and Earth Sciences, Duke Center for Marine Conservation, 135 Duke Marine Lab Rd., Beaufort, North Carolina 28516-9721, USA
4MarineLab, Marine Resources Development Foundation, 51 Shoreland Drive, Key Largo, Florida 33037, USA
5Present address: Florida State University Coastal and Marine Laboratrory, 3618 Highway 98, St. Teresa, Florida 32358-2702, USA

ABSTRACT: The abundance of demersal marine fishes is a function of both pre-settlement processes that influence recruitment to benthic juvenile habitats, as well as post-settlement density-dependent processes that act during the juvenile stage. Few studies have investigated density-dependence for fishes that spawn offshore and recruit to inshore estuaries for the juvenile stage prior to returning to offshore waters as adults (i.e. estuary-dependent). We conducted 2 replicated experiments at different spatial scales to test for density-dependent growth and mortality in juvenile spot Leiostomus xanthurus, a common estuary-dependent species. In the small-scale experiment, we stocked spot in 1 m2 cages in a marsh creek at densities of 2, 5, and 10 fish m–2 and determined their growth and mortality after 51 d. In the large-scale experiment, we stocked spot in 79 m2 pond sections at 2, 5, and 10 fish m–2 and determined their growth and mortality after 52 d. We sampled benthic infauna at the end of the pond experiment to determine if prey availability mediated the effects of density on spot growth and mortality. Average spot growth rates decreased 83 to 97% and mortality increased 2- to 4-fold as density increased from 2 to 10 fish m–2. The density of benthic infauna at the end of the pond experiment was inversely related to spot density, consistent with competition for food as the underlying mechanism. Estimates of spot density compiled from the literature indicate that the density-dependent effects we observed occurred within the range of reported field densities. Our results provide strong experimental support for the hypothesis that density-dependent processes during the demersal juvenile stage in estuaries can modify patterns in the abundance of spot, and perhaps other estuary-dependent species, that are established prior to settlement.


KEY WORDS: Density-dependent growth · Density-dependent mortality · Spot · Leiostomus xanthurus · Estuarine nursery · Food limitation


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Cite this article as: Craig JK, Rice JA, Crowder LB, Nadeau DA (2007) Density-dependent growth and mortality in an estuary-dependent fish: an experimental approach with juvenile spot Leiostomus xanthurus. Mar Ecol Prog Ser 343:251-262. https://doi.org/10.3354/meps06864

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