A comparative study was carried out on the functional feeding behavior of the infaunal clam Mulinia edulis and the epifaunal mussel Mytilus chilensis from Yaldad Bay, southern Chile, in response to broad fluctuations in quantity and quality of seston. A number of physiological variables were quantified and compared, including clearance, filtration and ingestion rates; pseudofeces production and pre-ingestive selection efficiency. Relative sizes of the ctenidia and labial palps were measured for both species to determine if the size of the organs was related to their capacity for filtration and pre-ingestive particle selection. Both species showed high rates of clearance at lower seston concentrations (< 3 to 5 mg l -1 ). Above these concentrations, both species regulated both the quantity and quality of material ingested. When the seston concentration was relatively low and/or its quality high, regulation of food ingested was accomplished primarily by reduction in clearance rate, while at high seston concentrations and/or low quality, this parameter was regulated primarily by the expulsion of pseudofeces with a lower content of organic matter. Ingestion regulation was higher in M. chilensis. In general, both species showed a capacity for pre-ingestive particle selection, which increased with seston concentration and the proportion of organic matter present. In diets containing more than 60% organic matter, selection efficiency in M. chilensis became slightly reduced, while in M. edulis it remained stable; this observation is explained by the larger relative size of the labial palps in Mulinia edulis. Generally, feeding rates of M. chilensis were higher than those of M. edulis; this may be attributable to the former's larger-sized ctenidia, which are able to filter more food. KEY WORDS: Mulinia edulis · Mytilus chilensis · Infaunal and epifaunal bivalves · Feeding behavior · Particle selection · Diet quality · Chile tidal flats Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 240: [143][144][145][146][147][148][149][150][151][152][153][154][155] 2002 Foster-Smith 1975, , Newell & Jordan 1983, Ward & MacDonald 1996, Navarro & Widdows 1997. These studies suggest that both infaunal and epifaunal bivalves are able to affect pre-ingestive particle selection, which improves the quality of the matter ingested. In this manner, these organisms are able to adjust their feeding rates in order to maximise their acquisition of energy and avoid functional problems associated with particle saturation. A majority of studies on this topic were carried out using a narrow range of seston concentrations (2 to 30 mg l -1 ) in seawater that did not necessarily reflect natural seston concentrations, which may range to over 100 mg l -1 with extreme values of 500 mg l -1 (Falconer & Owens 1990). The few studies which have included high ranges of seston concentration (>100 mg l -1 ) used natural seston or diets made up of varying quantities of sediment to which known amounts of p...

Several experiments were performed examining the e¡ect of di¡erent culture variables on the growth and survival of Argopecten nucleus and Nodipecten nodosus larvae. Higher growth and survival values were obtained at a low density (1larvae mL À 1 ) than at a high density (5 larvae mL À1 ), except for N. nodosus's survival, which was not a¡ected by density. Higher growth was obtained when feeding the larvae a diet of Isochrysis galbana, similar results occurred with the diet of Isochrysis galbana 1 Chaetoceros calcitrans in A. nucleus and with I. galbana combined with the lipid emulsion EmDHA in N. nodosus. Higher survival was obtained when the diet included a mixture of microalgae than when EmDHA was supplemented. Growth and survival of the larvae of A. nucleus were greater when fed continuously, while N. nodosus grew and survived better when food was given discontinuously. Higher growth and survival values were recorded at lower food concentrations ranging from 20 to 40 cells mL À 1 of I. galbana. Higher growth was observed with increasing temperature between 22 and 28 1C, although there was a simultaneous decrease in survival. No signi¢cant e¡ects on larval production parameters were found when the culture water was changed totally or partially, but higher larval growth of N. nodosus was veri-¢ed when a partial renewal of water was performed.

No abstract

No abstract

No abstract

No abstract

No abstract

No abstract