Testing the Habitat Safety Hypothesis with behavioural field experiments: amphipod orientation on sandy beaches with contrasting morphodynamics

TitleTesting the Habitat Safety Hypothesis with behavioural field experiments: amphipod orientation on sandy beaches with contrasting morphodynamics
Publication TypeJournal Article
Year of Publication2009
AuthorsFanini, L, Defeo O, Do Santos C, Scapini F
JournalMarine Ecology Progress Series
Volume392
Pages133-141
KeywordsAtlantorchestoidea brasiliensis, Habitat Safety Hypothesis, orientation, Sandy beaches, Sun compass
Abstract

Understanding behavioural adaptations in sandy beach macrofauna has been a major
step in theoretical development of sandy beach ecology. In particular, behavioural studies in supralittoral
amphipods have been useful in understanding macrofaunal responses and adaptations to
environmental changes in these dynamic ecosystems. The predictions of the Habitat Safety Hypothesis
(HSH) were tested for the first time on Atlantorchestoidea brasiliensis through orientation
experiments carried out on 2 sandy beaches, one dissipative and the other reflective. Orientation patterns
of A. brasiliensis followed the trend predicted by the HSH: even though sandhoppers oriented
seawards on both beaches using a sun compass, the orientation on the reflective beach was more precise
than on the dissipative one. Thus, stability conditions in the supralittoral zone of the reflective
beach favoured a higher precision of the sun compass. The precision of seawards orientation on the
dissipative beach increased when landscape references were added to the sun compass mechanism.
The response to an unexpected object was also experimentally tested by use of a visual pattern, and
a higher individual variability in the orientation of the reflective beach population was found. Thus,
orientation strategies in sandy beach environments seem to respond to the stability of the supralittoral
zone, widening the general pattern predicted by the HSH for the supralittoral fauna to the
behavioural traits of the population.

DOI10.3354/meps08219

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