Hermit crabs and their symbionts: Reactions to artificially induced anoxia on a sublittoral sediment bottom

Autor(en)

Katrin Pretterebner, Bettina Riedel, Martin Zuschin, Michael Stachowitsch

Abstrakt

Hermit crabs play an important role in the Northern Adriatic Sea due to their abundance, wide range of symbionts, and function in structuring the benthic community. Small-scale (0.25 m(2)) hypoxia and anoxia were experimentally generated on a sublittoral soft bottom in 24 m depth in the Gulf of Trieste. This approach successfully simulates the seasonal low dissolved oxygen (DO) events here and enabled studying the behaviour and mortality of the hermit crab Paguristes eremita. The crabs exhibited a sequence of predictable stress responses and ultimately mortality, which was correlated with five oxygen thresholds. Among the crustaceans, which are a sensitive group to oxygen depletion, P. eremita is relatively tolerant. Initially, at mild hypoxia (2.0 to 1.0 ml l(-1) DO), hermit crabs showed avoidance by moving onto better oxygenated, elevated substrata. This was accompanied by a series of responses including decreased locomotory activity, increased body movements and extension from the shell. During a moribund phase at severe hypoxia (0.5 to 0.01 ml l(-1) DO), crabs were mostly immobile in overturned shells and body movements decreased. Anoxia triggered emergence from the shell, with a brief locomotion spurt of shell-less crabs. The activity pattern of normally day-active crabs was altered during hypoxia and anoxia. Atypical interspecific interactions occurred: the crab Pisidia longimana increasingly aggregated on hermit crab shells, and a hermit crab used the emerged infaunal sea urchin Schizaster canaliferus as an elevated substrate. Response patterns varied somewhat according to shell size or symbiont type (the sponge Suberites domuncula). Mortality occurred after extended anoxia (similar to 1.5 d) and increased hydrogen sulphide levels (H2S similar to 128 mu mol). The relative tolerance of crabs and certain symbionts (e.g. the sea anemone Calliactis parasitica) - as potential survivors and recolonizers of affected areas - may influence and promote community recovery after oxygen crises.

Organisation(en)

Institut für Paläontologie

Externe Organisation(en)

Universität Wien

Journal

Journal of Experimental Marine Biology and Ecology

Band

411

Seiten

23-33

Anzahl der Seiten

11

ISSN

0022-0981

DOI

https://doi.org/10.1016/j.jembe.2011.10.027

Publikationsdatum

2012

Peer-reviewed

Ja

ÖFOS 2012

106001 Allgemeine Biologie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/49f18549-ed45-424e-80d1-8e03215224ca