Monitoring salt marsh vegetation and nekton at Gateway National Recreation Area’s Sandy Hook Unit: 2010 summary report

Patenaude, Erika; Pooler, Penelope

The Northeast Coastal and Barrier Network (NCBN) is one of 32 networks of parks created by the National Park Service (NPS) Inventory and Monitoring Program (I&M Program). The I&M Program has two components, 1) to collect baseline ecological inventory datasets and 2) to implement Vital Signs monitoring, a long-term ecological monitoring program, in each of the 32 networks. The Northeast Coastal and Barrier Network consists of eight parks linked by geography and shared ecological characteristics along the Northeastern Atlantic Coast. As part of the I&M Program, each network has developed detailed protocols for monitoring a select number of Vital Signs, or ecological indicators. Because the majority of parks in the NCBN are coastal parks, salt marsh monitoring was chosen as a high priority and protocols were developed for collecting long-term data on salt marsh vegetation and nekton (James-Pirri and Roman In Review-a,b). The objective of monitoring vegetation and nekton is to identify long-term trends in community structure, and to provide resource managers with a better understanding of the current status and condition of the salt marsh resources they manage.This report summarizes the first year of vegetation and nekton data collected at Gateway National Recreation Area’s Sandy Hook Unit (GATE-SHU) in 2010. The salt marsh at GATE-SHU is not very extensive, and therefore a complete sample of all salt marsh habitat was conducted. The marsh was delineated into three monitoring sites ranging from approximately 6.5 to 15 ha in size. Monitoring data will be collected at these sites biennially. Fifty vegetation plots were sampled at each of the three marsh sites in August of 2010. The percent cover of each vegetation species and non-vegetation cover type within each 1 m2 plot was visually estimated using a revised Braun-Blanquet method (Kent and Coker 1992). Twenty-eight vegetation species and five non-vegetation cover types were recorded during sampling in 2010. Non-vegetation cover types recorded included wrack & litter, bare ground, rock, water, and trash. Spartina alterniflora (salt marsh cordgrass) was by far the most abundant and frequently observed species.A total of 18 nekton stations were sampled at two marsh sites. The third site was not suitable for nekton sampling. Nekton in marsh pools (Site 3) and large tidal creeks (Site 1) were sampled with a 1m2 aluminum throw trap (Kushlan 1981, Sogard & Able 1991, Raposa and Roman 2001). A total of 12 species of nekton were recorded at GATE-SHU in 2010, including eight fish species, two crab species, and two shrimp species. Examination of percent catch data indicates that two species account for approximately 95% of all nekton captured. The most prevalent species, Fundulus heteroclitus (common mummichog), accounts for approximately 59% of all nekton recorded at GATE-SHU in 2010. The second most common species, Menidia menidia (Atlantic silverside), accounts for approximately 25% of all nekton recorded and was much more abundant in June than in August. Palaemonetes pugio (daggerblade grass shrimp) accounts for approximately 11% of all nekton recorded and was more abundant in August. Substantial differences in abundances and species composition between the two sampling visits are to be expected and reinforce our decision to sample nekton twice during the summer.

Monitoring salt marsh vegetation and nekton at Gateway National Recreation Area’s Sandy Hook Unit: 2010 summary report

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