Abstract. The removal of glycine and glucose by freshly collected adult Mytilus edulis was determined using radiolabeled substances added to ambient concentrations of dissolved organic materials in freshly collected natural sea water. Uptake rates were calculated for substrate concentrations of 0.5 μM glycine and 1.0 μM glucose and were compared with the animals' energy and nitrogen demands as measured by oxygen consumption and ammonia excretion rates. Respiration and ammonia excretion rates as well as cither glycine or glucose removal were all determined for the same animals. The mean respiration rate was 670μl O2 g-1h-1, the mean ammonia excretion rate 1.95 μg-at NH4-g-1 h-1. The calculated uptake rates were 0.48 μmol -g-1-h-1 for free amino acids and 0.44 μmol-g-1 h-1 for free simple sugars. Such uptake rates could have contributed roughly 13% of the mussels' energy requirements or 10% of the mussels' nitrogen requirements assuming the following conditions: 0.5 μM concentration of free amino acids, 1.0μM concentration of simple sugars, uptake of total amino acids at a rate based on a weighted removal rate of glycine, alanine, serine, and glutamic acid, and uptake of simple sugars at a rate equal to that of glucose removal. It is apparent that simple organic substances dissolved in sea water may be of some benefit to mussels, especially when the substances occur in concentrations typical of coastal sea water. 相似文献
Mussels Mytilus galloprovincialis were exposed to different concentrations of estradiol (20, 200, and 2000 ng/l) in a semi-static regime (1-day dosing intervals) for up to 7 days in an attempt to see how mussels dealt with exogenous estrogenic compounds. Sex hormone levels were determined in whole tissue. Free-estradiol was only significantly elevated at the highest exposure dose (up to 10-fold). Most of the estradiol was in the tissues as fatty acid esters (>78%), which sharply increased in a dose-dependent manner (from 4 ng/g in controls to 258 ng/g at the high exposure group). In contrast, neither free nor esterified testosterone levels showed significant differences between control and exposure groups. The results suggest the existence of mechanisms that allow mussels to maintain their hormonal status, and the important role that fatty acid esterification may play within those mechanisms. Synthesis and conjugation rates of estradiol were further investigated by measuring the activity of P450 aromatase, and palmitoyl-CoA:estradiol acyltransferase, in digestive gland microsomal fractions. Overall, the study contributes to the better knowledge of molluscan endocrinology, and defines new mechanisms of regulation of free steroid-levels in mussels. 相似文献
Blue mussels (Mytilus edulis) taken from several sites in the Mersey Estuary, an urban-industrial water body in NW England, have been analyzed for residues of the persistent organochlorines, DDT, PCB congeners nos. 28, 52, 101, 118, 138, 153 and 180 (ICES7), and alpha-MHCH (alpha-methyl hexachlorocyclohexane). The concentration range for sigmaPCB (ICES7) was 13.9-34.9 microg kg(-1) in 1994 compared with 9.6-31.9 microg kg(-1) in 1998, whilst the equivalent concentrations of sigmaDDT were 8.9-32.4 microg kg(-1) and 4.5-16.8 microg kg(-1), respectively. The concentration of alpha-MHCH, an organochlorine largely restricted to the Mersey Estuary, was 1.2-11 microg kg(-1) in 1994 and 0.3-1.3 microg kg(-1) in 1998. At both sampling dates the inner estuary sites of Rock Ferry and Egremont were more contaminated than the outer estuary sites of New Brighton. Dove Point and Caldy Blacks. The lower concentrations of organochlorines in mussels in 1998 compared with 1994 are thought to be early evidence of significant improvements in water quality derived from major capital investment in the treatment of industrial effluents and sewage wastewater, linked to a combination of stricter legislative controls and the environmental benefits from the adoption of new, clean technologies in manufacturing. 相似文献
The aim of this investigation was to develop appropriate methods for quantitative assessment of blue mussel beds. Combined methods of remote sensing, ground truth investigation and sampling in the field were applied to mature and young intertidal mussel beds. Three variables were measured to obtain reliable quantitative estimates of biomass and abundance: the total area covered by a bed; the cover, i.e. the area of mussel-covered patches in relation to the total mussel bed area; and the proportion, i.e. the area covered by mussels within the patches in relation to the total area of mussel patches. Cover and proportion of intertidal blue mussel beds were measured in the field by the transection method. Aerial photographs enabled the total area of the beds to be determined and large-scale surveys of mussel beds to be carried out synchronously. By examining large-scale aerial photographs it was possible also to determine the cover by remote sensing. The proportion could not be derived from aerial photographs, even from pictures at the largest scale tested during this investigation (scale 1:2500). By statistical methods it was estimated that 12 sub-samples (each covering 177 cm2) from mature beds, and 12 sub-samples (each covering 38 cm2) from young beds are needed to obtain reliable data on biomass and abundance. 相似文献
Abstract. Three successive years of recruitment failure, intensive fishery, and high rates of natural mortality eliminated all intertidal mussel beds and nearly all cockle beds from the Dutch Wadden Sea in the course of 1990. In late 1990 and early 1991, zoobenthic biomass and particularly bivalve stocks were unprecedentedly low. The following unusual events were noted:
1)
Relatively high diatom and chlorophyll concentrations in the autumn of 1990 and an exceptionally early and dense spring bloom of diatoms in March 1991;
2)
Exceptionally early onset of rapid growth in the bivalve Macoma balthica in March 1991;
3)
Above-average weights of the soft parts of bivalves in the 1990/91 winter;
4)
Elevated mortality rates in bivalves that could serve as alternative prey for birds specialised on big bivalves (oystercatchers and eiders);
5)
Signs of food shortage in such birds: high mortality rates and emigration to other feeding areas;
6)
A rapid recovery of the benthos started in the summer of 1991, accelerated by an exceptionally high recruitment in some of the affected species.
It is concluded that the Wadden Sea ecosystem responded in an elastic way to the removal of two of its key species. The events are not seen as merely coincidental but are regarded as a chain of causes and effects. 相似文献
Many aquatic organisms are negatively affected by exposure to high copper concentrations.We investigated the biochemical response of the mussel Mytilus coruscus(Mytiloida:Mytilidae) to copper exposure.In vivo bioassays using M.coruscus and different copper concentrations were conducted.The activity of six biomarkers,namely superoxide dismutase(SOD),catalase(CAT),acid phosphatase(ACP),alkaline phosphatase(AKP),glutamic-oxaloacetic transaminase(GOT) and glutamic-pyruvic transaminase(GPT) were measured.Survival rates decreased with increased copper concentrations and exposure times.The LC50 values at 48,72,and 96 h exposure were 0.48,0.37,and 0.32 mg/L,respectively.Within digestive glands,CAT activity increased with increasing Cu concentrations.The activity of AKP showed no significant change,while the remaining four enzymes showed decreasing activity with increasing Cu concentrations.Within the gills,AKP activity increased when the Cu concentration was 0.05 mg/L,but showed no significant changes at higher concentrations.Activity of CAT and ACP within gills tended to decrease with increasing Cu concentration.The activity of SOD and GPT decreased at an exposure concentration of 0.2 mg/L.GOT activity within gills decreased at 0.1 mg/L and increased at an exposure concentration of 0.2 mg/L.Within the adductor muscle,AKP activity increased at 0.05 mg/L but did not change at higher exposure concentrations.ACP activity within adductor muscle tissue showed no change,while activities of CAT,GOT and GPT decreased with increasing Cu concentrations.SOD activity within the adductor muscle tissue significantly decreased at the 0.02,0.05 and 0.2 mg/L exposure concentrations.Our results show tissue specific differences for the six biomarkers in for M.coruscus.Our findings provide the basis for the establishment of reference activity levels against which biomarker changes can be estimated,and are essential preliminary steps in development of in vivo bioassays. 相似文献