PREFERENTIAL SUBSTRATUM FOR FEEDING AND BURROING IN UCA SPECIES FROM BRAZILIAN SOUTHEASTERN

COLPO KARINE; NEGREIROS-FRANSOZO MARIA LUCIA

FLORIANÓPOLIS - SC - BRASIL

Congreso; III Congresso Brasileiro sobre Crustáceos; 2004

The preference of the substratum by six species of fiddler crabs (U. thayeri, U. leptodactyla, U. vocator, U. burgersi, U. maracoani and U. rapax) was experimentally tested by means examination of feeding and burrowing activities, Each species was analyzed apart in 40 replicates (20 males and 20 females). The recipients (44 em of diameter by 19 cm of height) used in the experiment were divided in three compartments, which were filled with substratum of three different composition. The first sediment was constituted, mainly, by silt and clay (65.3%); the second was represented by very fine sand (78,9%), and the third one by coarse and very coarse sand (35.8%), After 24 hours of exposition to the different sediment the burrows and pellets presence in each kind of sediment was recorded. The results were compared among treatments by means Multinomial proportion analysis (p<0,05). The species 1.1. thayeri and 1.1. rapax do not presented any feeding preference, however the former preferred (65%) to burrow in the muddy substratum, The species Uca leptodactyla, .u, yocator and .u, burgersi ate in a similar way in the sand and coarse sand sediments. ~ leptodactvla and-U, burgersi did not present preference concerning burrowing actiVity, while 81,1% of the U. vocator specimens burrowed in the mud. With respect to the species .u, maracoani, it was not verified pellets formation, but all specimens did burrows in the mud (100%). Despite of the assumption of previous authors, mainly concerning the ecological distribution aspect offiddler crabs biology, we can assume  the preferred substratum for built burrows are not necessarily the same for feeding purpose. Thus the fiddler crabs studied here seem to be more flexible than it was though in the past, once they can inhabit a variety of microhabitat