Effects of coastal orientation and depth on the distribution of subtidal benthic assemblages

Abstract

A better understanding of biological systems can only be gained if we understand what processes are important and how they operate to determine the distribution of organisms. Coastal orientation and depth can influence environmental conditions, including the degree of water motion and availability of light, which in turn may influence the horizontal and vertical patterns of organism distribution. Here, we used a mixed-model design to examine the effects of coastal orientation and depth on the structure of benthic assemblages by comparing the abundance and distribution of macroalgae and invertebrates in shallow and deep waters on the opposing coasts of São Miguel. Generally, coastal orientation had little influence on the distribution of most taxa. In contrast, significant differences were generally associated with depth, although patterns were spatially variable at the scale of locations. This study suggests that depth, and processes operating at the scale of location, but not at the scale of the coast, have an important influence on these assemblages, and that failure to recognise such a scale of variability may hamper our ability to better understand the processes that structure these communities.

Distribution and population structure of deep‐dwelling red coral in the Northwest Mediterranean

“…Martins et al . ). The substrates on which red coral patches were settled were mainly exposed to the NW–W at Amalfi and E–SE at Ischia.…”

Epiphytic flora on <em>Gelidium corneum</em> (Rhodophyta: Gelidiales) in relation to wave exposure and depth

“…Indeed, wave exposure is one of the major factors directly or indirectly influencing the structure of algal assemblages (Rindi and Guiry 2004, Nishihara and Terada 2010, Borja et al 2013. Although increasing wave action is a key factor in supplying nutrients for macroalgae (Martins et al 2013), hydrodynamic pressure can also remove epibionts and prevent them from settling (Kersen et al 2011). The mechanical stress produced by higher wave-action (Kraufvelin 2007) could favour the removal of epiphytes at NW oriented locations in our study, whereas at N oriented locations lower hydrodynamic levels could favour their development.…”

“…Increasing irradiance levels usually favour algal development and growth (Altamirano et al 2000, ColomboPallotta et al 2006). Therefore, due to the exponential decay of light intensity with increasing depth (Gross et al 2003, Martins et al 2013, shallower waters may be expected to contain higher epiphyte loads Fotedar 2010, Tsirika et al 2007). Our findings partially support this hypothesis.…”

Species richness, relative abundance and dwarfism in Azorean bivalves: consequences of latitude, isolation or productivity? Or all three?

“…A sub-sample obtained from three stations (5% of the total), that is, 6, 7 and 19, located at depths of 40–41 m, 167–189 m and 23 m, respectively, were analysed in detail to provide an assessment of the numbers of each identifiable bivalve species taxon present and their sizes (shell lengths). The three samples were chosen to represent different depths from the shore of the steeply sloping island because Martins et al (2013) has shown that the distribution of benthic taxa offshore from São Miguel varies with depth and scale of the location, but not with the scale of the coast. Subsequently, the entire collection of bivalve specimens obtained from the 60 stations, encompassing the large scale of the coast, and previously rough-sorted, was examined to obtain a measure of the shell lengths of the largest individuals of each species obtained.…”