Estimating and Applying Fish and Invertebrate Density and Production Enhancement from Seagrass, Salt Marsh Edge, and Oyster Reef Nursery Habitats in the Gulf of Mexico

Philine S E Zu Ermgassen,Kara Meckley,Sophus Zu Ermgassen,Sean Powers,Jonathan R Gair,Bryan Deangelis,Andre Daniels,Timothy C Macdonald,Ronald Baker,Jonathan H Grabowski,Marta Ribera,Lawrence P Rozas

doi:10.1007/s12237-021-00935-0

Abstract

Seagrasses, oyster reefs, and salt marshes are critical coastal habitats that support high densities of juvenile fish and invertebrates. Yet which species are enhanced through these nursery habitats, and to what degree, remains largely unquantified. Densities of young-of-year fish and invertebrates in seagrasses, oyster reefs, and salt marsh edges as well as in paired adjacent unstructured habitats of the northern Gulf of Mexico were compiled. Species consistently found at higher densities in the structured habitats were identified, and species-specific growth and mortality models were applied to derive production enhancement estimates arising from this enhanced density. Enhancement levels for fish and invertebrate production were similar for seagrass (1370 [SD 317] g m–2 y–1for 25 enhanced species) and salt marsh edge habitats (1222 [SD 190] g m–2 y–1, 25 spp.), whereas oyster reefs produced ~650 [SD 114] g m–2 y–1(20 spp). This difference was partly due to lower densities of juvenile blue crab (Callinectes sapidus) on oyster reefs, although only oyster reefs enhanced commercially valuable stone crabs (Menippe spp.). The production estimates were applied to Galveston Bay, Texas, and Pensacola Bay, Florida, for species known to recruit consistently in those embayments. These case studies illustrated variability in production enhancement by coastal habitats within the northern Gulf of Mexico. Quantitative estimates of production enhancement within specific embayments can be used to quantify the role of essential fish habitat, inform management decisions, and communicate the value of habitat protection and restoration.

Highlights

Coastal habitats in temperate and tropical estuaries provide a diverse array of valuable ecosystem services that humans rely upon
Marsh edge in parts of Galveston Bay was reduced by 70% between 1982 and 1995 due primarily to sea level rise and shoreline erosion (Rozas et al 2007), and marsh area declined by 20% bay-wide since the 1950s (White et al 1993, cited in Levin and Stunz 2005)
The presence or addition of structured habitat supports the addition of recruits to the population over and above the recruitment that occurs in the absence of that habitat, as observed in Eurasian perch (Perca flavescens) in the Baltic Sea (Sundblad et al 2014), in Sparidae on rocky reefs around Australia (Folpp et al 2020), and as previously demonstrated across numerous species associated with eastern oyster reefs in the USA (Peterson et al 2003, zu Ermgassen et al 2016)

Summary

Introduction

Coastal habitats in temperate and tropical estuaries provide a diverse array of valuable ecosystem services that humans rely upon. Each habitat provides a physically complex structure shown to increase survival and growth of recently settled fish and invertebrates, and densities of juvenile nekton associated with these habitats are often high (Heck et al 2003; Hollweg et al 2020a; Lefcheck et al 2019). Where such structured nursery habitats have been lost, populations of species that are associated with the habitat as juveniles may be habitat limited (Folpp et al 2020). The degradation and loss of these habitats here and elsewhere has often resulted in their replacement by unstructured soft sediments

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