Quantifying Feeding Behavior of Ribbed Mussels (Geukensia demissa) in Two Urban Sites (Long Island Sound, USA) with Different Seston Characteristics

Abstract

The Atlantic ribbed mussel, Geukensia demissa, is found in salt marshes along the North American Atlantic Coast. As a first step to study the possibility of future cultivation and harvest of ribbed mussels for nutrient removal from eutrophic urban environments, the feeding behavior of ribbed mussels in situ was studied from July to October 2011. Two locations approximately 80 km apart were used as study sites: Milford Harbor (Connecticut; 41°12′42.46″N, 73°3′7.75″W) and Hunts Point (Bronx, New York; 40°48′5.99″N, 73°52′17.76″W). Total particulate matter was higher at Hunts Point than at Milford Harbor, but the organic content was higher at Milford than at Hunts Point. The relatively low quantity of organic content in Hunts Point seston resulted in a much higher production of pseudofeces by mussels. Mussel clearance and absorption rates were higher at Milford Harbor than at Hunts Point. Nevertheless, mussels at both sites had the same absorption efficiency, suggesting that mussels are able to adapt to conditions at both locations. Ribbed mussels decreased clearance rate when the seston quantity was high at both sites. At Hunts Point, ribbed mussels increased the gut transit time of ingested particles when the amount of inorganic particulates in the water increased. This study does not quantify nutrient removal capacity of G. demissa; however, the environmental tolerance demonstrated here, and current lack of commercial harvest, suggests that this species may be a good candidate for nutrient bioextraction in highly impacted urban environments.

Transplant experiment to evaluate the feeding behaviour of the Atlantic ribbed mussel, Geukensia demissa, moved to a high inorganic seston area

“…The seston variables recorded during this study were within the range of Hunts Point seston reported previously (TPM from 6.59 to 19.41 mg L À1 ; POM from 1.53 to 3.45 mg L À1 ; PIM from 4.88 to 15.95 mg L À1 ; and ORG from 15.71 to 29.87%) (Galimany et al 2013a), and we believe the values reported here are representative of typical conditions at this location. Hunts Point has characteristics of shallow, tidally mixed, estuarine ecosystems where tides, wind, and shallow depth result in resuspension of the sediment from the bottom, reducing the Clearance rate CR L h À1 (mg inorganic matter from both faeces and pseudofaeces per unit of time (mg h À1 ))/(mg inorganic matter (PIM; mg L À1 ) in bay water) Filtration rate FR mg h À1 CR Â total particulate matter (TPM; mg L À1 ) in the bay water Total rejection rate TRR mg h À1 mg of inorganic and organic matter from pseudofaeces per unit of time (mg h À1 ) Organic ingestion rate OIR mg h À1 (CR Â Particulate organic matter (mg L À1 ) in the water) À (rejection rate of organic matter (mg h À1 )) Absorption rate AR mg h À1 OIR À (egestion rate of organic matter) Absorption efficiency AE fraction AR/OIR Selection efficiency SE fraction 1 À [(organic fraction within pseudofaeces)/(organic fraction within total particles available in bay water)] relative organic content of suspended particulate matter (Hawkins et al 1996b;Velasco and Navarro 2005;Galimany et al 2011).…”

“…The organic matter in the seston was very similar throughout the study and much lower than the inorganic matter. The organic content of the seston ( f ) was 22.73 AE 3.88, 17.28 AE 0.99 and 18.82 AE 3.22% for the 3 different days of experiments, within the same range as observations made during 2011-12 at the same site (22.58 AE 4.32%) but much lower than the range observed in Milford Harbor (43.38 AE 9.21%) (Galimany et al 2013a).…”

“…Such high inorganic fraction values were never found in Milford previously; for example, TPM had an average value of 5.81 AE 0.21 mg L À1 and organic matter averaged 43 AE 9%. The particulate loads measured in the present study and by Galimany et al (2013a) at Hunts Point were above the limit of the pseudofaeces threshold for mussels, which for M. edulis is reported to be ,5.0 mg L À1 (Widdows et al 1979;Bayne et al 1993). As described in the Introduction, the seston characteristics from Hunts Point and Milford Harbor had consistently different total particulate loads.…”

“…The determinations were made with endemic ribbed mussels, Geukensia demissa, and those obtained from Milford, CT. Two portable, flowthrough devices designed and used to quantify mussel feeding on natural seston were used as in Galimany et al (2013a). Each determination was conducted with a different group of similarly sized ribbed mussels (average lengths 58.8 AE 4.1 cm for Milford mussels and 63.7 AE 6.0 cm for Milford mussels) collected at the respective sites.…”

“…In 2011-12, local populations of ribbed mussels were studied at two sites that were ,100 km apart: Milford, CT, and Hunts Point, Bronx, NY (USA), as a first step to determine how effective aquaculture of G. demissa could be for nutrient bioextraction (Galimany et al 2013a). The study demonstrated that ribbed mussels from the two locations studied used different feeding strategies to adapt to the characteristics of the water they inhabited, and both populations achieved the same absorption efficiency despite contrasting seston characteristics at the two sites.…”