Fish Use of Mitigated Salt Marshes in the United States

Defense Date

6-13-2003

Document Type

Capstone

Degree Name

M.S. Marine Biology

Second Degree Name

M.S. Coastal Zone Management

First Advisor

Steffen Schmidt

Second Advisor

Andrew Rogerson

Abstract

Salt marshes are an essential component of the temperate coastal ecosystem, providing a variety of ecological functions including acting as a nursery for commercial fishery species and as habitat for an array of resident fish and invertebrates. Fish use in salt marshes is determined not only by the behavior and ecology of a given region's fish populations, but also by topographic, geomorphologic and hydrological features such as sinuosity, channel morphology, and tidal flow. Commercially important species tend to be transient and favor more subtidal habitats, while resident species use more of the intertidal and marsh surface areas. Although seemingly separate, both guilds of fish perform critical roles in the salt marsh ecosystem as predators, forage and by the transfer of biomass and energy. · Development, agriculture and pollution have led to the dramatic reduction of salt marsh habitat throughout the U.S. Policy efforts have lessened the spread of degradation somewhat, but the losses continue. One method to reduce this problem is mitigation - the restoration or creation of salt marshes. A major question with salt marsh mitigation is whether or not they are functionally equivalent to natural systems. Frequently this question is underestimated through overly simplistic assessment criteria. The mitigation of salt marshes is generally beneficial to coastal fish populations, as it aids in restoring and creating habitat for these species. However, community composition is often unbalanced and population abundances can be smaller than natural marshes. Biodiversity is frequently higher in mitigated marshes, but this is usually due to an influx of opportunistic species or an excess of subtidal habitat and the associated species. Closer attention to marsh morphology, more appropriate reference marshes, and expanded monitoring are all factors in improving salt marsh mitigation to benefit both fish populations and the general health of the entire ecosystem.

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