Geographic variation in the macrofaunal associates of pelagic Sargassum and some biogeographic implications

Abstract

The macrofauna associated with individually collected clumps of pelagic Sargassurn was influenced strongly by the location of sampling. Algae collected in the Sargasso Sea carried more species with lower dominance and higher evenness and variation in abundance than algae collected in the Gulf Stream. Gulf Stream samples were dominated by the shrimp Latreutes fucorum (67.8 %) with little compositional variation whereas the gastropod Litiopa melanostoma was the most abundant but weakly dominant species (25.1 %) in the Sargasso Sea. Generally, species endemic to pelagic Sargassum species were most abundant in the Sargasso Sea while numerous temporary associates were found in the Gulf Stream. Numbers of individuals and species increased with the weight of algal clumps but clump size had little effect on the species composition of algal associates. Variation in species composition and trophic organization of macrofaunal associates with geographic region and with algal age were related to differences in the epiphytization of the algae. Because of the dissimilarity in algal associates of the Gulf Stream and Sargasso Sea, the influx of littoral fauna from the West Indies to the Sargasso Sea is probably very slow and the present forms may have evolved in that water mass.

Habitat Selection Among Fishes and Shrimp in the Pelagic Sargassum Community: The Role of Habitat Architecture

“…Results showed that the more densely branched mimic "complex alga" had a greater number of amphipods, which also showed a dependence on both size-specific selections for the structural and spatial components of habitat architecture. These results have also been reported in other studies (Heck and Wetstone, 1977;Crowder and Cooper, 1982;Coull and Wells, 1983;Edgar, 1983aEdgar, , 1983bEdgar, , 1983dStoner and Lewis, 1985;Dean and Connell, 1987a, 1987b, 1987cHacker and Steneck, 1990). Habitat architecture should be explored not only horizontally (i.e., patch size or how densely packed the alga is arranged), but also vertically (the depth the alga covers in the water column).…”

Distribution ofSargassum natans and some of its epibionts in the Sargasso Sea

“…Many authors have reported on the temporal and geographical variation of the mobile fauna (Timmermann, 1932;Fine, 1970;Butler et al, 1983;Stoner & Greening, 1984) but regarding the sessile fauna and flora mainly qualitative descriptions are available (Hentschel, 1922;Prat, 1935;Burkenroad, 1939;Weis, 1968;Morris & Mogelberg, 1973;Woelkerling, 1975;Butler et al, 1983). Quantitative analyses have been carried out in relation to settlement and succession of epibionts by Conover & Sieburth (1964) and Ryland (1974).…”

Rapid changes in the epifaunal community after detachment of buoyant benthic macroalgae

“…The composition of rafting communities on macroalgae collected from the sea surface after extended floating periods has been studied by Stoner & Greening (1984), Hobday (2000) and Tsikhon-Lukanina et al (2001). Similarly, experimental investigations have focused on later successional stages of the rafting community on detached and tethered macroalgae that had been suspended in the water column or at the sea surface for weeks to months (Edgar, 1987;Vásquez, 1993;Ingólfsson, 1998).…”