Seagrass Habitats as Nurseries for Reef-Associated Fish: Evidence from Fish Assemblages in and Adjacent to a Recently Established No-Take Marine Reserve in Dry Tortugas National Park, Florida, USA

Abstract

Scientists and managers worldwide have increasingly advocated the use of marine protected areas (MPAs) to protect at—risk fish stocks. Most MPAs, however, have been established to protect reefs, while nonreef habitats, such as seagrasses, have received less consideration. In January 2007, an MPA called the Research Natural Area (RNA), was established as a no—take marine reserve in the Dry Tortugas National Park, Florida (DTNP), becoming the first MPA within the park boundaries to offer direct protection to seagrasses and reef habitat. We conducted a study using small— mesh Antillean Z—traps to (1) characterize fish assemblages in seagrass and reef habitats and (2) assess if differences in community structure existed between the RNA and adjacent open—use areas. Over 3 sampling events (Fall 2009, Spring 2010, Fall 2010), 3,163 individuals of 38 species were collected from 129 stations. Fish assemblages differed significantly among sampling events and between habitat types, but no differences were evident between the RNA and open—use areas. Unlike previous sampling efforts that focused on larger—bodied fish in the DTNP, Z—traps targeted small—bodied reef— and seagrass—associated fishes. Juvenile Haemulon plumierii and Epinephelus morio strongly contributed to community structure and were more abundant in seagrass habitats, which may serve as an important nursery area. Because the RNA was only established 2 years before this study was conducted, it could still be several years before benefits to the juvenile population become evident, but this study establishes the importance of considering seagrass habitats when developing a reef—associated no—take marine reserve.