The influence of habitat, season and tidal regime in the activity of the intertidal crab Neohelice (=Chasmagnathus) granulata.

LUPPI TOMÁS; BAS CLAUDIA; MÉNDEZ-CASARIEGO, AGUSTINA; ALBANO, MARIANO; LANCIA, JUAN; KITTLEIN, MARCELO; ROSENTHAL, ALAN; FARÍAS, NAHUEL; SPIVAK EDUARDO; IRIBARNE OSCAR

HELGOLAND MARINE RESEARCH

SPRINGER

Lugar: Berlin; Año: 2012 vol. 67 p. 1 - 15

1438-387X

Abstract The activity pattern of intertidal crabs is inXuenced by factors that usually change rhythmically following tidal and/or diel cycles, and is often associated with the use of refuges. The movement activity of the burrowing crab Neohelice granulata was compared among three populations from SW Atlantic coastal areas where they face diVerent tidal regimes, water salinities, substrata and biological factors. At each site, we examined the seasonal activity of the crabs (individuals collected in pitfall traps) in two types of habitat: mudXat and salt marsh. The working hypothesis is that the activity would vary according to the diverse environmental conditions encountered at geographical and local scales. Crab activity varied between sites and seasons showing to be more intense when habitats were covered by water. The most active groups were large males, followed by large non-ovigerous females. Ovigerous females were almost inactive. Most crabs were near or inside burrows at low tides in Mar Chiquita and Bahía Blanca, but they were active at both low and high tides in San Antonio during spring and summer. N. granulata were active in a wide range of temperatures: from 10 to 37 °C at low tides and at temperatures as low as 2 °C when covered by water. DiVerences of activity between mudXat and salt marsh varied among sites depending on Xooding frequencies. Movement activity of N. granulata varied both in space and in time; crabs move under very diVerent abiotic conditions (e.g., low or high tide, daylight or night, low and high temperature) and their movement may also be prevented or elicited by biotic conditions like burrow complexity, food quality and predation pressure. The wide set of conditions under which N. granulata can be active may explain why this is the only semiterrestrial crab inhabiting latitudes higher than 40°S in South America.