Corridors and Recruitment of Coral Reef Fishes Ethan G.P. Machemer 1, John F. Walter III 2, and David W. Kerstetter 1 1 Nova Southeastern University Oceanographic Center 8000 North Ocean Drive; Dania Beach, FL National Oceanic and Atmospheric Administration, Southeast Fisheries Science Center 75 Virginia Beach Drive; Miami, FL Future Research Acknowledgements This research used data from the Mangrove Visual Census conducted by Joe Serafy (NOAA SEFSC) and the Reef Visual Census conducted by Jim Bohnsack (NOAA SEFSC). Additional support from Dave Jones (RSMAS) is also gratefully acknowledged. Extension of visual surveys to focus on observed species, location, size, and depth within channel. Measure abundance of species in mangrove poor locations, and those with limited access between mangrove and coral reef sites. Are current protected areas adequate to ensure healthy juvenile to adult populations? Introduction Materials and Methods Objectives Results Establish a link between abundances of juvenile fish in mangroves and abundances of adult fish on coral reefs. Define channels used for the movement between these two habitats. Haemulon parra Locations of largest fish counts associated with the mouths of key channels (Figs. 2 & 3). Individuals remained in the mangroves beyond juvenile size if channel not within 10 km (Table 1). Mangrove Visual Census (c) and Reef Visual Census (d) data over the years were obtained for Abudefduf saxatilis, Gerres cinereus, Haemulon parra, Lutjanus apodus and Scarus guacamaia. Data included individual fish counts on the coral reef running parallel to the Florida Keys and the Mangrove stands adjacent to Florida Bay and Card Sound. Point counts of individual species were performed noting size, number, depth, GPS location, and salinity among other variables. Multiple sampling surveys were made throughout each year. Using ArcGIS, species specific locations were plotted according to individual length and the number of individuals occurring at that site. Straight line distances were measured from nine channel openings in the Florida Keys to the sites of reef aggregations. Ontogenetic shifts occur in habitat utilization from mangroves to coral reefs for many teleost fish species (Fig. 1). However, there must be routes or corridors used for the travel to accomplish these shifts. For this research, a corridor is defined as an area of specific bathymetry and salinity that links the mangrove habitats to the reefs through channels in the outlying barrier islands. Channels in the upper Keys have volume transport between m 3 /s (a), and median current speeds of cm/s (b), so there may be an energetic benefit involved to utilizing these as transport mechanisms to offshore reefs. Is it possible to define movement and the habitat of the transition stage individuals to better understand this life stage, and adequately manage the levels and areas of these populations? Background Image from: Figure 1. Juvenile fish within mangrove prop roots a: Lee, T.N., and N.P. Smith Volume transport variability through the Florida Keys tidal channels. Continental Shelf Research 22: 1361–1377. b: Gibson, P.J., J. N. Boyer, N.P. Smith Nutrient Mass Flux between Florida Bay and the Florida Keys National Marine Sanctuary. Estuaries and Coasts. 31: c: Serafy J.E., Faunce C.H., Lorenz J.J Mangrove Shoreline Fishes of Biscayne Bay, Florida. Bulletin of Marine Science 72: 161–180 d: Bohnsack, J. A., S. P. Bannerot A stationary visual census technique for quantitatively assessing community structure of coral reef fishes. NOAA Technical Report NMFS, 41: 15 p. Figures 2 & 3. Locations of Observed Fish in Upper Keys mature Gerres cinereus Size-Frequency Distribution Size (cm) Frequency (% of distribution) Haemulon parra Size-Frequency Distribution Size (cm) Frequency (% of distribution) mature Species% at MaturityMean Distance (km) Abudefduf saxatilisMangrove: 10.40% / Reef: 62.84% / Gerres cinereusMangrove: 20.07% / Reef: 69.88% / Haemulon parraMangrove: 17.33% / Reef: 90.91% / Lutjanus apodusMangrove: 1.589% / Reef: 43.48% / Scarus guacamaiaMangrove: 16.27% / Reef: 81.74% / Table 1. Percent of Mature Stage Individuals vs. Mean Distance from channel opening Scarus guacamaia Wilson Key Channel Indian Key Channel Tavernier Creek Snake Creek North Sound Creek South Sound Creek Rhodes Channel Angelfish Creek Hurricane Creek Scarus guacamaia Gerrescinereus Haemulon parra Abudefduf saxatalis Lutjanus apodus Site Number Increasing Distance from Channel Mangrove Sites Increasing Distance from Channel Reef Sites