Growth, filtration and respiration in the mussel Mytilus edulis:no evidence for physiological regulation of the filter-pump to nutritional needs

Abstract

The specific growth rate of blue mussels Mytilus edulis fed Rhodomonas sp. algal cells in laboratory experiments increased with increasing food concentration to obtain a maximum value of about 9 . 5 % d-', irrespective of a relatively h~g h concentration of silt (5 mg 1.' ) added to the water. Ltkewise, the net growth efficiency increased with the spec~fic growth rate to a maximum value of about 75%. Measurements of the relationship between respiration and growth showed that the energy cost of growth constituted 12% of the growth. The filtration rate of a 100 mg dry wt 'standard' mussel was high and constant (about 30 m1 rnin-l) at algal concentrations below about 6000 cells ml-' when measured in both short-time (5 h) and long-time (9 to 14 d ) experiments High algal concentrations of 1.3 to 2.4 x 10?ells ml-' reduced the filtration rate by about 40":). The estimated growth, presuming maximum filtration rate, satisfactorily descnbed the actual growth a t algal concentrations <5000 cells ml-', and the concentration necessary for maximum growth was estimated at 4500 cells rill-' (corresponding to 5.6 big chlorophyll a I-']. The mean specific growth rate in M edubs transferred in net bags to a fjord system (Kert~nge Nor/Kerteminde Fjol-d, Denmal-k) was about 6% d-' The results show that there is no physiological regulation of the filtration rate to nutritional needs, and that food uptake in nature (median concentration in Danish waters = 5

Preingestive selection processes in the cockle Cerastoderma edule: mucus production related to rejection of pseudofaeces

“…As in previous investigations (Navarro & Iglesias 1993, Urrutia et al 1996, Navarro & Widdows 1997, and in contradiction of some scientists who reject the concept of physiological regulation of feeding (Clausen & Riisgard 1996, Jørgensen 1996, we found in the present experiments that cockles increase processing rates when faced with an increase in particulate matter associated with a decrease in the quality of the suspension. Regulation of ingestion rate by means of keeping high rates of rejection coupled to high rates of filtration leads to a significant increment in the organic fraction of ingested matter, which, in turn, enhances the efficiency of digestive processes.…”

Artificial structures in sediment-dominated estuaries and their possible influences on the ecosystem

“…The total length of all groynes in this area was estimated from nautical charts, and the total abundance of sublittoral M. edulis was calculated. Total filtration performance was calculated using the filtration rates for M. edulis from the literature range from 1.5 to 3.0 l h À1 individual À1 (Mølenberg and Riisgård, 1979;Famme et al, 1986;Clausen and Riisgård, 1996).…”

Evaluation of the Danish mussel fishery: suggestions for an ecosystem management approach

“…Several experiments conducted both in the field (Fréchette and Bourget 1985;Fréchette et al 1989;Dolmer 2000a, b) and in flumes (Wildish and Kristmanson 1984;Butman et al 1994) have shown that suspension-feeding animals, including blue mussels, are able to deplete seston from the near-bed layer. This indicates that at least some sections of a mussel bed may be food-limited and a change in near-bed mixing may therefore affect individual growth, especially in the downstream parts of mussel beds (Fréchette and Bourget 1985;Fréchette et al 1989;Clausen and Riisgård 1996). Since blue mussels may close their valves in response to tactile stimuli from shorecrabs and other larger motile species, the mere presence of these animals will influence the filtration activity and hence the growth of these zoobenthic filter feeders.…”