A comparison of temporal turnover of species from benthic cnidarian assemblages in tropical and subtropical harbours

Abstract

An important component of species diversity which has recently received significant attention is the change in species composition across space, or beta diversity. Temporal turnover of species is an equally important component of species diversity, which can by itself account for diversity patterns, but has received much less attention, especially in marine communities. Indeed, patterns of diversity of marine epifaunal assemblages may be better understood through the study of variability in richness and composition of recruits that colonize and survive long enough to start a population, but before species interactions mask the diversity initially settled. Here we document temporal patterns in richness and composition of recruits of a speciose benthic cnidarian assemblage, contrasting a tropical and a subtropical site to evaluate simple predictions about latitudinal diversity and richness stability. Recruitment variation was quantified during five three-month periods at two harbour areas (Pecém at 3°32′S and Ilhabela at 23°46′S) in Brazil separated by 20°latitude. Results show that: (1) species richness of benthic cnidarian assemblages was higher at the more tropical location, as expected from general patterns in marine species global distribution; (2) contrary to the expectation of a negative association between richness and species turnover, temporal turnover of species was similar at both sites, although more seasonal at the higher latitude site; and (3) species temporal persistence was greater at the subtropical site. Results are discussed in the context of how different environments and different regional richness may influence temporal patterns in species turnover and local richness, and how this may vary across latitudes.

Environment and life cycles influence distribution patterns of hydromedusae in austral South America

“…Some biological aspects may explain the distribution of meroplanktonic hydromedusae. First, the discontinuous presence of medusae in the plankton may be compensated by the long-term presence of polyps in the benthos (Boero et al 1996), even though recruitment may occur seasonally in the tropical and subtropical areas studied (Migotto et al 2001;Fernandez et al 2014Fernandez et al , 2015. Second, medusa reproduction may be compromised after long-distance dispersal, because successful fertilization and planula recruitment are less likely (see also Boero 1984).…”

Mollusks on Recruitment Panels Placed in an Offshore Harbor in Tropical Northeastern Brazil

“…The richness of mollusks, the number of newly metamorphosed or very young individuals, and the variety of feeding habits found in this study show that the recruitment panels provide a microhabitat able to support different trophic guilds. Research using these same recruitment panels, conducted by Paiva (2013) and Fernandez et al (2015), reinforce the evident richness of this habitat. Paiva (2013) found great coverage percentages of ascidians and bryozoans, as well as other groups, such as polychaete worms, sponges, hydroids, bivalves, octocorals, barnacles, and anemones.…”

“…Paiva (2013) found great coverage percentages of ascidians and bryozoans, as well as other groups, such as polychaete worms, sponges, hydroids, bivalves, octocorals, barnacles, and anemones. Also, Fernandez et al (2015) studied the temporal patterns in richness and composition of benthic cnidarian assemblage.…”

Areas of endemism in the Southwestern Atlantic Ocean based on the distribution of benthic hydroids (Cnidaria: Hydrozoa)

“…Seasonality and population dynamics of hydroid species (viz., Gili & Hughes 1995;Bavestrello et al 2006;Rossi et al 2012;Fernandez et al 2014Fernandez et al , 2015 are influenced by marine abiotic and biotic factors that, ultimately, may constitute geographic barriers for some species although not influencing the distribution of others. Temporal variation of species richness in assemblages of benthic hydroids has already been described, and two types of species in Hydrozoa have been recognized: species recruiting to new surfaces year-round, and species doing so sporadically and without strong seasonality (Migotto et al 2001;Fernandez et al 2014).…”