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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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This paper explores the factors influencing or controlling West Indies reef fish assemblages, using an extensive underwater survey (mensurative experiment). The sampling units represented variation in substrate type, depth, and geography. For that, the distribution of coastal species assemblages was examined in different islands, from the Dominican Republic in the north to Bequia (Grenadines) in the south. Visual surveys were made by snorkeling and SCUBA diving in various habitats from the surface to 55 m deep. Presence-absence data from 248 sites and 228 species were analysed by canonical redundancy analyses. Three quantitative variables (depth, latitude, and location of the sites along the Caribbean arch) as well as qualitative descriptors corresponding to 10 habitat types were used as explanatory variables in the canonical analyses. Variation partitioning showed that substrate was the most important factor, accounting for 15.2% of the species variation, while the geographic gradients explained 8.4%; 2.3% was explained jointly by the two groups of variables. Most of the variation explained by depth was also accounted for by the substrate categories. In a canonical analysis of community composition by substrate types, the first canonical axis divided the sites into soft substrates characterized by few species and hard substrates characterized by several other species. The second axis separated the outer reef slopes, with low or high coral cover and sandy areas with coral patches (deep habitats) from shallow non-reef rocky substrates and reef fronts. A second canonical analysis of community composition by geographic gradients produced an ordination of the sites in which the succession of islands along the Caribbean arch is recognizable. The species are positioned in the ordination according to their contributions to the fauna of the various islands. This paper supports the hypothesis that fish community composition in the Caribbean islands is controlled mostly by a latitudinal and a hydrologic gradient, as well as by the type of habitat and, with a lower influence, by depth. .
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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The Point Conception, California, USA region (hereafter PC) is one of the most important biogeographic and oceanographic discontinuities on the US west coast. Here we address how mesoscale oceanographic variability in the region around PC affects the growth of the competitively dominant species in the rocky intertidal assemblage: the mussel Mytilus californianus. Strong upwelling and high wave exposure dominate the California coast north of PC, and weak, seasonal upwelling and warmer water temperatures are characteristic of the region south/east of PC. We hypothesized that the oceanographic gradients in temperature, upwelling, wave exposure and productivity around PC would exert strong bottom-up influences on growth rates of mussels, potentially underlying large-scale differences in community structure around the PC region. We evaluated these predictions by measuring mussel growth rates across the PC region both in the intertidal and offshore on moorings. Intertidal mussels grew at much higher rates at sites south relative to north of PC and growth rates decreased in a gradient from south to north. The gradient in intertidal mussel growth around PC was uncorrelated with inshore concentrations of chlorophyll-a, and was most strongly correlated with the alongshore gradient in wave exposure and intertidal temperature. Mussels on moorings offshore from the intertidal sites grew at much higher rates than those in the corresponding intertidal areas, and mussel growth rates did not differ significantly among moored locations around PC. The gradient of increasing temperature from north to south among mooring sites was correlated with a decreasing gradient in productivity in the same direction, potentially contributing to equal and opposite effects on mussel growth at offshore moorings. This study suggests that environmental factors such as cold temperatures and high wave exposure contribute to the spatial pattern of decreasing mussel growth rates from south to north around PC, underlying large-scale patterns of community structure in this region. .
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This digital document is an article from Arctic, published by Arctic Institute of North America of the University of Calgary on December 1, 1998. The length of the article is 7142 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

Citation Details
Title: Birds of the Indigirka River Delta, Russia: historical and biogeographic comparisons.
Author: John M. Pearce
Publication:Arctic (Refereed)
Date: December 1, 1998
Publisher: Arctic Institute of North America of the University of Calgary
Volume: 51 Issue: 4 Page: 361-70

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