Factors Influencing Colonization and Survival of Juvenile Blue Crabs Callinectes sapidus in Southeastern U.S. Tidal Creeks

Paul J Rudershausen,Jeffrey A Buckel,Jeffery H Merrell

doi:10.3390/d13100491

Abstract

Tidal creeks along the southeastern U.S. and Gulf of Mexico coastlines provide nursery habitats for commercially and ecologically important nekton, including juvenile blue crabs Callinectes sapidus, a valuable and heavily landed seafood species. Instream and watershed urbanization may influence the habitat value that tidal creeks provide to blue crabs. We investigated natural and anthropogenic factors influencing juvenile blue crab occupancy dynamics in eight first-order tidal creeks in coastal North Carolina (USA). An auto-logistic hierarchical multi-season (dynamic) occupancy model with separate ecological and observation sub-models was fitted to juvenile blue crab presence/absence data collected over replicate sampling visits in multiple seasons at three fixed trapping sites in each creek. Colonization and survival are the processes operating on occupancy that are estimated with this formulation of the model. Covariates considered in the ecological sub-model included watershed imperviousness, the percent of salt marsh in each creek’s high tide area, percent salt marsh edge, site-level water depth, and site-level salinity. Temperature, salinity, and dissolved oxygen were covariates considered in the observation sub-model. In the ecological sub-model, watershed imperviousness was a meaningful negative covariate and site-level salinity was a positive covariate of survival probability. Imperviousness and salinity were each marginally meaningful on colonization probability. Water temperature was a positive covariate of detection probability in the observation sub-model. Mean estimated detection probability across all sites and seasons of the study was 0.186. The results suggest that development in tidal creek watersheds will impact occupancy dynamics of juvenile blue crabs. This places an emphasis on minimizing losses of natural land cover classes in tidal creek watersheds to reduce the negative impacts to populations of this important species. Future research should explore the relationship between imperviousness and salinity fluctuations in tidal creeks to better understand how changing land cover influences water chemistry and ultimately the demographics of juvenile blue crabs.

Highlights

Introduction published maps and institutional affilDevelopment is increasing from 300–600% faster than human population growth in United States (U.S.) coastal zones [1], with these impacts impeding the ability of estuaries to serve as critical nurseries for resident and transient nekton species [2]
A total of 176 juvenile blue crabs were captured in 118 trap sets giving a 14.9% observed occupancy
We found that colonization and survival probabilities increased with increasing site-level salinities; the trend was most pronounced for the effect of salinity on survival and is consistent with increasing survival with higher salinities in a study of tethered juvenile blue crabs in the Cape Fear

Summary

Introduction

Introduction published maps and institutional affilDevelopment is increasing from 300–600% faster than human population growth in United States (U.S.) coastal zones [1], with these impacts impeding the ability of estuaries to serve as critical nurseries for resident and transient nekton species [2]. It is estimated that half of salt marsh habitats has been lost in the U.S to urbanization of coastal seascapes [3]. Development in coastal areas severs aquatic habitat connectivity [3,4,5] and reduces secondary biological production [5,6,7,8]. Tidal creeks experience high secondary biological production [10,11] that, through tissue export, support valuable fisheries [12,13,14]. Acute losses of tidal creek salt marshes and adjacent upland buffers have occurred in this region [15,16]

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Results

Discussion

Conclusion