An Ecological Analysis of Nauset Marsh, Cape Cod National Seashore

Roman, Charles; Able, Kenneth; Heck, Kenneth; Fahay, Michael; Portnoy, John; Aubrey, David; Lazzari, Mark

Nauset Marsh is the most extensive and least disturbed salt marsh/estuarine system in Cape Cod National Seashore. It is a back-barrier estuary with direct exchange through an inlet to the Atlantic Ocean. Short form Spartina alterniflora marsh encompasses 35% of the system. Other important habitats include intertidal mudflats (12%), intertidal sandflats (11%), and eelgrass (Zostera marina) beds (6+%). Thirty-three percent of the system is associated with tidal kettle ponds and shallow tidal channels (<1-3 m). Very little ecological information existed for Nauset Marsh and thus the objective of this study was to obtain a quantitative ecological data base so that resource managers could more effectively assess significant adverse effects. Nauset Marsh is especially threatened by the cumulative effects of residential growth, and natural changes to the system's ecology will occur in association with migration of the geomorphically active Nauset Inlet. This three-year study, which began in July 1985, focuses on the system's major habitats and includes: (1) an assessment of primary production and biomass dynamics of the macrophyte-dominated habitats; (2) a seasonal inventory of fishes, decapod crustaceans, benthos, and birds, including select species life history studies and habitat-specific studies; and (3) an evaluation of circulation and water quality dynamics throughout the system. Water quality measurements included: total, organic, and inorganic suspended seston; dissolved oxygen; nitrate-nitrite, ammonia, total dissolved nitrogen, and dissolved organic nitrogen; orthophosphate, total dissolved phosphorus, and dissolved organic phosphorus; and dissolved organic carbon. Although Spartina alterniflora is considered the major macrophyte primary producer in Nauset Marsh and other north temperate salt marshes, it is concluded that other habitats also contribute significantly to total system carbon production. Forty-nine species of fish and 11 decapod crustacean species were collected. In terms of habitat distribution of fauna, the eelgrass habitat was found to support the greatest diversity for all fish and invertebrates (gastropods, bivalves, isopods, amphipods, decapods) collected except for polychaetes (mud substrate preferred). Most avian usage was by migrating shorebirds and wintering waterfowl. See the Executive Summary of the report (pp. ix-xii) for more details on the major findings of this study. Table of Contents include: Executive Summary. Introduction (Statement of Management Problem; Research Approach; Report Format). The Study Site (Inlet Dynamics; Physical Characteristics; Ecological Habitats). Primary Productivity & Biomass Dynamics (Primary Production of Habitats; Remote Sensing Analysis). Inventory & Habitat Utilization of Fishes and Macroinvertebrates (Fishes and Decapod Crustaceans; Benthic and Epibenthic Invertebrates; Habitat-Specific Studies). Bird Utilization (Introduction; Methods; Results and Discussion; Conclusions). Relationships between Water Quality & Habitats (Introduction; Methods; Results and Discussion; Conclusions). Long-Term Environmental Monitoring Program (Monitoring Objectives; Program Components; Program Implementation). Literature Cited. Research Appendices (A. Professional Manuscripts and Additional Literature; B. Abstracts of Professional Presentations; C. Student Thesis and Dissertation Research; D. Numerical Modeling of Nauset Inlet/Marsh; E. Nauset Reference Collection). Data Appendices (A. Field Sampling Schedule; B. Inventory of Benthic and Epibenthic Invertebrates; C. Bird Inventory and Annelid Prey Abundance; D. Water Quality Study Data).