Selective use of mangrove shorelines by snappers, grunts, and great barracuda

Abstract

We examined seasonal utilization of > 500 km of mangrove shoreline within a subtropical continental system by Lutjanus griseus, L. apodus, Haemulon sciurus, H. parra, and Sphyraena barracuda over 2 consecutive years. Mangrove use by these species was examined in terms of frequency of occurrence, density (fish 60 m -2 ), concentration (density among samples where number of fish ≥1), and selection (H 0 : habitat use = availability). All species exhibited either seasonal or spatial habitat selection. Mangrove shorelines closest to the reef tract (Keys) were used by snappers and grunts at much greater levels than their availability would suggest, whereas more inland and expansive mangrove shorelines were largely selected against. This selection pattern was evident year round for L. apodus, H. sciurus, and H. parra. In contrast, L. griseus preferred more inland mangroves during the dry season and Keys mangroves during the wet seasons. S. barracuda exhibited selection for Keys during the wet seasons and was the only species to exhibit non-selection (random) patterns among strata during the dry seasons. These results demonstrate that mangrove shorelines across broad spatial scales are not equivalent in their value as fish habitats, and that estimates of 'essential fish habitat' or 'nursery habitat' using total habitat area will grossly overestimate the amount of functional habitat used by these reef fishes. KEY WORDS: Essential fish habitat · Habitat selection · Delta approach · Snapper · Grunt · Great barracuda · MangrovesResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 356: 153-162, 2008 also evident for individual species belonging to the same functional group, i.e. reef fishes (Ley & McIvor 2001, Serafy et al. 2003. Martino & Able (2003) suggested that patterns in estuarine fish assemblage structure across large spatial scales (i.e. >10 km) are due to individual species responses to dominant environmental gradients. Following this logic, demonstrated that the distance between a sample location and an oceanic inlet (a proxy for crossshelf location) was primarily responsible for the separation of life-history stages of snappers and grunts within the mangrove shorelines of Biscayne Bay (southeastern Florida).The above studies are limited in that most considered shoreline mangroves as homogenous units and all ignored size or area of mangrove patches between locations. Thus they offer limited information about the relative importance or value of one mangrove stand compared to another. Although mangroves are gaining increased recognition as habitats that can enhance growth and survival of immature reef fishes, few studies have been conducted at sufficient spatial and temporal scales to examine variation in reef fish utilization within this habitat type (e.g. Faunce & Serafy 2006). These shortcomings are significant considering that the presence of mangrove-lined embayments enhances adult stocks of reef fishes in the western Atlantic (Dorenbosch et al. 2004, Mu...

Nocturnal fish utilization of a subtropical mangrove‐seagrass ecotone

“…While several recent studies have examined seasonal and spatial patterns of fish use of Biscayne Bay’s mangrove habitats, all have been focused on diurnal observations along the mangrove fringe (Serafy et al. 2003, 2007; Faunce & Serafy 2008b). In the present study, we used nocturnal seine net sampling to investigate nocturnal fish habitat use patterns at 20‐m intervals along a 120‐m transect extending from the mangrove edge across adjacent seagrass habitat.…”

Connectivity through ontogeny: fish population linkages among mangrove and coral reef habitats

“…ML, LK, and RF). Mangrove data were subsetted by ML and LK because previous work has consistently revealed significant differences in reef fish abundance between these 2 mangrove strata (Serafy et al 2003, Faunce & Serafy 2008. Global mean fish abundances, calculated by pooling abundances across years for each combination of age-class/ habitat strata, were subtracted from corresponding annual mean fish abundances.…”

Interactions among Foundation Species and Their Consequences for Community Organization, Biodiversity, and Conservation

“…By reducing water flow, modifying the substrate, and impeding the foraging efficiency of mobile predators, seagrass beds facilitate the settlement of benthic invertebrates and enhance the survivorship and density of prey species (Orth et al 1984, Heck et al 2003, Canion and Heck 2009. Similarly, along thousands of kilometers of Caribbean coastline, networks of red mangrove (Rhizophora mangle) roots provide essential nursery habitat for juvenile snappers, grunts, barracuda, and other fishes and physically guard these populations from larger predators (Beck et al 2001, Faunce andSerafy 2008). Consequently, the trophic dynamics associated with seagrass and mangrove communities arise largely from the biogenic framework provided by foundation species, which suggests a hierarchical community organization in which species and their interspecific interactions occur within a community that is itself established with the facilitation of a foundation species (Bruno and Bertness 2001).…”