ABSTRACT
Abstract Burrowing alpheid shrimps occur commonly in seagrass meadows and as such, are presumed to respond to the various sediment environments in which seagrasses are found. To determine the effects of sediment type on seagrass-associated alpheid shrimps, we examined burrows and the burrowing behavior of Alpheus macellarius, Chace, 1988, in three bed substrates – sand, muddy sand, and sandy mud – in laboratory cuvettes. Alpheus macellarius immediately excavated into all the substrates at initiation of the experiment and successfully established the first burrows within 2 hours (sand) to 1 day (muddy sand, sandy mud). Burrowing effort was highest and tunnel lengths were most extensive in sand after 26 days (p < 0.05). After 37 days, shrimp activity in all substrates was observed to shift to considerable wandering and feeding (mainly particle ingestion) became conspicuous. Burrowing behavior, though reduced, remained significantly higher in sand than in the other two substrates (p < 0.05). Overall, soft sandy sediments presented greater support for the burrowing behavior of A. macellarius, which, with reinforcement from dense seagrass, probably accounts for higher burrow densities in sand in the field. Conversely, shrimp burrowing appeared limited and substituted by concealment
strategies in terrigenous substrates. Hence, with less support from sparser vegetation in the field, burrow numbers were also reduced.
