Amino-acid uptake by mussels,Mytilus edulis, from natural sea water in a flow-through system

Abstract

Natural Wadden Sea water taken from the North Sea (island of Sylt) was pumped at rates of 150 and 300 1 h -1 through a 4 1 plexiglass tube mounted on a wooden tripod on the beach.The tube was densely filled with numerous cleaned mussels, Mytilus edulis. HPLC analysis of sea water showed that total dissolved amino acids are patchily distributed, varying by 100 % within 15 man, though proportions of individual amino acids were remarkably constant. Total amino-acid concentrations were 1528 _. 669 nM (N ~ 3) in October 1983 and 1198 _ 597 nM (N = 7) in July 1984. Samples taken at the entrance and the outlet of the experimental mussel bed revealed that the mussels had taken up 29 to 66 % of the amino acids dissolved in sea water. Uptake was observed for all amino acids detected in the chromatograms. 78 % of uptake resulted from the 5 most concentrated amino acids: serine, alanine, glycine/threonine, ornithine, aspartic acid. The nutritional profit obtained from uptake of dissolved amino acids amounted to 12 % (N ~ 5, range 5-23 %, flow rate 150 1 h -1) and to 24 % (N = 3, range 13-38 %, flow rate 3001 h -1) of metabolic rate. The present data suggest that amino-acid concentration predominantly determines the magnitude of the nutritional profit obtained from uptake, and to a smaller extent the flow rate. These findings are in contrast to results of previous studies on Asterias rubens, interacting in small-volume closed systems with the natural bacterial sea water flora (Siebers, 1982). In these experiments, bacteria, due to rapid uptake, outcompeted the sea stars in absorption of dissolved amino acids. The present results suggest that bivalve mussels, can, due to their large gill surface areas and the great amounts of water pumped through their mantle cavity, successfully compete with bacteria in uptake of dissolved organic matter. Mussels, therefore, suggestedly play an important role in cycling dissolved organic matter.

Influence of temperature, salinity, and oxygen on the cadmium balance of mussels Mytilus edulis

“…Pretreatment of the experimental water with heat may have denatured seasonally low levels of &ssolved organlc matter. Such substances may contribute significantly to the nutrition of marine invertebrates including mussels (Siebers & Winkler 1984). In other experiments conducted in wlnter (unpubl.)…”

Uptake of dissolved organic matter (DOM) and its importance to metabolic requirements of the zebra mussel, Dreissena polymorpha

“…Even presuming a 100% filtration efficiency for all particles regardless of size, potential particle uptake was always Ͻ10% of observed uptake. Other workers who used radiography have also shown that 14 C-labeled organic compounds are taken up into the epidermal tissues of bivalves and not into bacteria living on tissue surfaces (Jordan and Valiela 1982;Manahan et al 1982;Siebers and Winkler 1984). Abiotic adsorption onto mucous surfaces is also very unlikely given that dead freshwater organisms do not accumulate organic substances at rates approaching those of live organisms (Testerman 1972;Thomas et al 1984).…”

Differential uptake of dissolved and particulate organic carbon by the marine musselPerna viridis

“…Despite this, some studies have suggested that the uptake of DOC is not nutritionally significant for marine invertebrates because bacteria respond more quickly to DOC and reduce its concentration to a low level (Siebers 1982;Ambariyanto and Hoegh-Guldberg 1999). The DOC, mostly released by biogenic activity (Biddanda and Benner 1997;Wang and Guo 2001), consists of all types of biochemical products, including carbohydrates (Biersmith and Benner 1998).…”

“…Siebers and Winkler (1984) reported that mussels took up 30-50% of the dissolved amino acids and obtained nutritional benefits from the uptake equivalent to 5-38% of their metabolic requirements. Rice and Stephens (1987) documented that 10 amino acids were taken up by the mussel Mytilus edulis and the oyster Crassostrea gigas, and then distributed rapidly into the internal tissues.…”