PREP Reports & Publications

Abstract

Understanding the dynamics of coastal marine communities represents a substantial challenge, and one that is actively pursued globally. Within the United States, several sites have been designated as National Estuarine Research Reserves (NERR) with the idea that concentrated research at these sites will lead to greater understanding of the ecosystem. The Great Bay Estuary of New Hampshire is one of these sites. A wide spectrum of research is conducted within the Great Bay, and substantial financial support is committed to that research on an annual basis. To facilitate the success of these research efforts, it is particularly important to develop a working understanding of the dynamics of marine communities within the Great Bay. Invertebrate communities within the Bay and at other coastal sites are largely composed of open populations whose growth and maintenance depend on settlement of new recruits that may arrive from distant source populations. Larval monitoring programs designed to survey these incoming recruits should therefore be an important component of the research program within the Great Bay and other NERR sites. By monitoring recruitment within the Great Bay, we may begin to determine larval spatial patterns within potential habitats. This will then allow for comparison of observed larval spatial patterns and observed adult population distributions. If the two are similar, this would indicate that future adult populations can be predicted by knowledge of larval settlement. If the two are dissimilar, this indicates a need to investigate causes of post-settlement mortality that lead to discrepancies in larval and adult abundances. For example, if there is a large discrepancy between larval and adult abundances, then the Great Bay may be acting as a sink for some species whose larvae are transported into the bay, but do not survive to establish adult populations. By monitoring invertebrate recruitment into the Great Bay, we begin to establish a baseline for biotic conditions within the Bay against which future conditions can be compared. This is a crucial step in determining the effects of anthropogenically induced environmental changes, such as the introduction of nonindigenous species. Furthermore, we predict that because a sufficient influx of larvae is needed to establish a viable adult population, larvae of exotic species not currently present in Great Bay will be first detectable in the plankton, perhaps for several years before they arrive in sufficient numbers for adults to establish. This may provide an advanced warning of incipient invasions and allow managers to develop plans for eradication or mitigation in advance of the exotic species’ establishment. Here we report on a study designed to collect the baseline data necessary to establish patterns and make comparisons to future conditions. We have collected larvae on artificial settlement substrates at six sites within the Great Bay Estuary and at an adjacent coastal site during ice-free months since July 2002. This report gives a brief description of the results of this monitoring program to determine the species composition, spatial patterns, and timing of invertebrate settlement within the Great Bay. This report specifically includes data from April 2005 to June 2006, the portion of the project funded by NHEP. Data from 2002-04 are also available, but are not included in this report.

Department

Piscataqua Region Estuaries Partnership

Publication Date

7-5-2006

Publisher

New Hampshire Estuaries Project

Document Type

Report

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