Ecology of brittle stars associated with biological microhabitat / Ecologia de ofiuroides associados a microhabitats biologicos

AUTOR(ES)

Alessandra Pereira Majer

DATA DE PUBLICAÇÃO

2008

RESUMO

The association of brittle stars with other marine species is a common strategy, usually related with cryptic habit. However, the influence of microhabitat’s characteristics over brittle stars populational parameters and behavior is not reasonably known. This study aimed to enlighten this influence over brittle stars associated with the algae Amphiroa beauvoisii, Dictyota cervicornis, Galaxaura stupocaulon and Sargassum furcatum; the sponges Amphimedon viridis and Mycale angulosa; and the ascidian Phalusia nigra. Seven brittle stars species were observed in sampled hosts, these, in order of abundance, where: Ophiactis savignyi, Amphipholis squamata, Ophiothrix angulata, Ophiactis lymani, Ophioplocus januarii, Ophiothela sp. and Amphiodia atra. The first four were observed in all microhabitat, specially as juveniles, and chemoreception trials, in general, did not present a preference of brittle stars towards tested hosts. Therefore the higher abundance of brittle stars in some microhabitats is not result of an active choice of host, but may be due to differential predation. The higher predation risk associated with the coralline alga A. beauvoisii was indirectly evidenced by the alarm signaling results. Both A. squamata, and O. savignyi sampled in this host, presented a wide recognition of signal (to both conspecific and heterospecific stimuli), while individuals of this last species sampled in sponges, that were considered to provide both physical and chemical shelter, did not. Microhabitat also influenced recruitment predictability, with a higher variability being observed in populations associated with the coralline algae, even for species with adaptations to increase recruitment number or survival rate. A tendency of higher mortality and lower growth rate was also observed in this host when compared with sponge populations.

ASSUNTO(S)

crescimento mortalidade fital habitat (ecologia) growth mortality phytal ophiuroidea nicho (ecologia) ofiuroides

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