CONICET | Buscador de Institutos y Recursos Humanos

Benthic-pelagic coupling is a key ecological process in coastal systems, with suspension-feeding benthic organisms playing a significant role. Suspension-feeders such as bivalve mollusks, not only provide important ecosystem services, but also constitute significant economic revenue for local and regional economies. Considering capture and aquaculture together, the majority of the world fishery production of marine mollusks, corresponds to suspension-feeders (66%) constituting an estimated gross value of > 13 billion dollars. The mytilid Brachidontes rodriguezii, dominates macrofaunal rocky intertidal communities in Buenos Aires Province, reaching biomass of 1.7 kg.m-2. Despite its dominance and uniqueness, no studies have been performed on its filtration capacity and modulation of benthic-pelagic coupling. The objective of this study was to experimentally characterize the physiological filtering response of this mytilid, attending to the seasonal and regional variability of the plankton food source. Experiments were carried out using natural seawater from two locations (i.e. open coast, and Mar Chiquita coastal lagoon) in different seasons. The experimental design incorporated static hambers (3-9 L), under laboratory and field conditions. Autotrophic biomass in seawater (chlorophyll a) was estimated spectrophotometrically. Microplankton (e.g. diatoms, dinoflagellates, ciliates) and zooplankton (e.g. copepodids, larvae) were enumerated from preserved samples by inverted light microscopy and under a dissecting scope, respectively. The clearance rate of particles from natural plankton suspensions was calculated from the extinction rate of chlorophyll a, and the different components of the plankton community. Overall, clearance rates were high (ranging from 4.2 ± 0.4 to 12.7 ± 1.6 l h-1 gDW-1), and comparable to those of other mytilids. Moreover, there were significant differences in clearance rates for total- and the

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