Evaluating ribbed mussels for nutrient bioextraction purposes: the Bronx (NY, USA) experience

Abstract

Nutrient bioextraction using suspension-feeding mollusks has been proposed as a tool to combat eutrophication of coastal waters resulting from human nutrient loading. We evaluated how much organic matter native ribbed mussels (Geukensia demissa) could remove from an urban location in the Bronx River (New York City, USA). In situ measurements were done to quantify the feeding behavior of mussels. Results showed that, despite a paucity of organic matter in the seston, mussel absorption efficiency (AE) was very high, reaching 0.73±0.11%. Organic ingestion rate (OIR) had a positive relationship with seston organic content, and nearly all of the organic seston component filtered was ingested. A commercial, 37 m2 mussel raft was placed at the site. A total of four, 7.6 m pegged ropes (30.4 m) and five, 6-m mesh socks (30 m) were seeded with an average biomass of 136 kg of mussels, a fraction of the raft’s fully-stocked capacity of 15 Tn. From the filter-feeding data (AE and OIR) we calculated that ribbed mussels could potentially remove from 0.38 Kg h-1 to 3.92 Kg h-1 of organic matter (and the nitrogen in that organic matter) for a mussel raft containing 15 Tn of adult mussels. We suggest that a site with a higher percentage of organic matter in the seston would support higher absorption rates of organic matter, and that the ribbed mussel is well-suited for nutrient bioextraction in eutrophic areas closed to harvest of commercial bivalve species