Interaction between a mobile and a sessile species in SW Atlantic mudflats: Lack of negative effects of the mud crab Cyrtograpsus angulatus Dana, 1851 on filtration rate and growth of the infaunal clam Tagelus plebeius (Lightfoot, 1786)

ADDINO, M.; F. ALVAREZ; O. IRIBARNE,; B.J. LOMOVASKY

JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 476 p. 65 - 71

0022-0981

Biogenic modifications of benthic environment by organism's activities like feeding, burrowing or excretion havein general negative implications for cohabiting sessile infauna, especially for suspension-feeders. However, theoutcome of these interactions depends on several biological and physical characteristics and thus, it is not easilypredictable in soft bottomenvironments. The stout razor clamTagelus plebeius, an estuarine, infaunal and sessilefilter feeder species, coexists in Mar Chiquita coastal lagoon (Argentina, 37° 32′S, 57° 19′W) with the mud crabCyrtograpsus angulatus, a very mobile benthic consumer. Due to the intense crab activity and consequent habitattransformation, we predicted negative effects on clams' filtration rate and their growth. However, an inclusionexperiment showed that T. plebeius filtration rate was higher in enclosureswhen crabs were present respondingto enhanced turbidity and chlorophyll a. Additionally, another experiment showed thatmean condition index aswell as mean shell growth increment of clamswas not negatively affected by crabs, althoughmaximumvalues ofshell growth increments (mm) were smaller in crab inclusions. Our findings suggest that the clams can exploitthe increased food availability (i.e., Chl a) generated by resuspension and are also not affected by the disturbancethat crabs can make over sediment surface. In conclusion, contrary to the generalized outcome proposed for thiskind of interaction, crabs do not have a negative effect on T. plebeius.