Influence of habitat configuration on connectivity between fish assemblages of Caribbean seagrass beds, mangroves and coral reefs

Abstract

The importance of seagrass beds and mangroves as juvenile habitats for coral reef fishes is still debatable. We hypothesised that the configuration of these habitats in the marine landscape in relation to the coral reef would influence accessibility from the reef (both for fishes that use these habitats for shelter or feeding, and their predators). In combination with differences in habitat complexity (related to habitat type) this could influence the utilisation of these habitats by juvenile reef fishes, and connectivity with the coral reef. Using underwater visual census, we studied the use by juvenile reef fishes of various seagrass and mangrove habitats situated differently in relation to the coral reef, on the Caribbean island of Aruba. Additionally, we studied fish assemblages on various coral reefs differing in proximity to seagrass Thalassia testudinum and mangrove Rhizophora mangle habitats at the scale of the whole island. In the seagrass and mangrove habitats, habitat configuration in relation to the reef was related to the composition of the fish assemblage, species richness, fish density and fish size. This was consistent with our expectations related to accessibility of these habitats from the reef, and habitat complexity. Most fish species that use seagrasses and mangroves as juvenile habitats were absent from or showed reduced densities on coral reefs located far (> 9 km) from seagrass-mangrove habitats. At a smaller spatial scale, this effect was less clear. For some species, this lack of an effect at smaller spatial scales may be explained by local recruitment to the reef, whereas for other species (i.e. Haemulon sciurus, Lutjanus apodus, L. mahogoni and Scarus guacamaia) migration along the coast offers a more likely explanation. We suggest that the value of seagrass and mangrove habitats as a juvenile habitat should not be generalised a priori, since habitat configuration may interact with the degree of connectivity between seagrasses, mangroves and coral reefs.

Patterns of scale-dependency and the influence of map resolution on the seascape ecology of reef fish

“…Correlation with these variables increased with analysis distance such that maximum r values occurred at the 800 m scale, a broader scale of peak correlation than identified by prior research (400 m by Kendall 2005; 500 m by Grober-Dunsmore et al 2007). It has long been thought that the area of surrounding seagrass increases the number of fish species on hard bottom sites by providing foraging areas for some species (Randall 1965, Ogden 1976, Nagelkerken et al 2000, transfer of energy to reefs (Meyer et al 1983, Meyer & Shultz 1985, nursery habitat (Dorenbosch et al 2005, Adams et al 2006, Dorenbosch et al 2007, Verweij et al 2008, and enhanced recruitment (Shulman & Ogden 1987, Cocheret de la Morinière et al 2002. Similarly, area of surrounding sand bottom may result in enhanced recruitment to nearby hard bottom sites of the many species that initially settle in sand habitat to avoid reef and reef edge predators (Helfman et al 1982, Shulman 1985, Shulman & Ogden 1987.…”

Habitat Connectivity of Fish in Temperate Shallow-Water Seascapes

“…However, when fish length data were obtainable, adult and juvenile life stages were determined using their length at maturity (Froese and Pauly, 2015). When specific maturity data were unavailable, a method commonly used to determine life stage was employed, by which individuals 1/3 of the maximum recorded length (according to FishBase) are considered to be juveniles (Dorenbosch et al, 2004(Dorenbosch et al, , 2007Unsworth et al, 2009). …”

“…Nagelkerken et al (2013) proposed the "seascape nursery" as a conceptual model that defines a mosaic of coastal habitats as an interlinked entity. While some research in tropical regions has evaluated the seascape nursery concept and the strength of connectivity between shallow-water areas (e.g., Nagelkerken et al, 2000;Dorenbosch et al, 2007;Gullström et al, 2012;Berkström et al, 2013a,b), this has seldom been investigated in temperate regions. In temperate shallow coastal waters, fishhabitat associations have been studied in various biomes such as seagrass meadows and rocky bottoms (e.g., Wennhage and Pihl, 2002;Jackson et al, 2006;Pihl et al, 2007;Hutchinson et al, 2013) though the focus on habitat connectivity has often been overlooked.…”

“…A tremendous effort has been made toward describing and comparing distribution patterns of fish in different shallow-water habitats (e.g., Dean et al, 2000;Mathieson et al, 2000;Able, 2005;Dorenbosch et al, 2007;Reiss et al, 2010), such as the significant role of seagrass meadows as nursery grounds (reviewed by Heck et al, 2003). However, in temperate waters the strength of habitat linkages and the relative importance of multiple habitats from a seascape perspective (considering ecological functions in relation to spatial patterns) has, as yet, been given sparse attention (see Perry et al, 2017;Staveley et al, 2017).…”

Variación entre hábitats de la densidad y composición por tallas en peces de arrecife de la región noroccidental de Cuba

“…For the census, we targeted a priori a selected group of reef fish species considered habitat-shifters (sensu Adams et al, 2006) by several authors (Cocheret de la Moriniere, Pollux, Dorenbosch et al, 2007). These species were from the families: Serranidae (genera Cephalopholis, Epinephelus and Mycteroperca), Lutjanidae, Haemulidae, Chaetodontidae, Scaridae and Acanthuridae, and Lachnolaimus maximus (Labridae) and Sphyraena barracuda (Sphyraenidae).…”