Filter feeding by the freshwater mussel, Diplodon chilensis, as a biocontrol of salmon farming eutrophication (original) (raw)
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Goods and Services of Marine Bivalves
Cultured and wild bivalve stocks provide ecosystem services through regulation of nutrient dynamics; both by regeneration of nutrients that become available again for phytoplankton production (positive feedback), and by extraction of nutrients through filtration and storage in tissue (negative feedback). Consequently, bivalves may fulfil a role in water quality management. The magnitude of regulating services by filter feeding bivalves varies between coastal ecosystems. This review uses the blue mussel as a model species and evaluates how cultured mussel stocks regulate nutrient dynamics in oligo-meso-and eutrophic ecosystems. We thereby examine (i) the eco-physiological response of mussels, and (ii) the positive and negative feedback mechanisms between mussel stocks and the surrounding ecosystem. Mussel culture in nutrient-poor areas (deep Norwegian fjords) are compared with cultures in other coastal systems with medium-to rich nutrient conditions. It was found that despite differences in eco-physiological rates under nutrient-poor
Freshwater Mussels as Biofilters
PhD Thesis, 2004
Freshwater mussels (Bivalvia: Unionidae) are filter feeders, removing phytoplankton and other suspended particulate matter from the water. The removal of suspended matter from water is often considered desirable, in order to reduce algal blooms and in the treatment of drinking water. This thesis investigates the potential role of freshwater mussels as living filters, or “biofilters”, in a variety of settings. Initial measurements of the filtration rates of British freshwater mussels showed that individual mussels can filter up to half a litre of water per hour. Calculations of the filtration rates of mussel populations in four British rivers indicate that mussel filtering removes between 7% and 30% of the particulate matter in a parcel of water travelling 10km downstream. This implies that mussels play an important role in the removal of suspended particulate matter in river ecosystems. In a large-scale experiment on the Ouse Washes RSPB reserve, mussels were placed in three eutrophic ditches to assess their potential use in the biomanipulation of these ditches. Although mussels suffered high mortality in two ditches, in the third ditch 70% of mussels survived, and the section of ditch containing mussels remained clear of floating macrophytes throughout the summer. However, mussels had little effect on the water quality in ditches, and further work is needed before they are used in future biomanipulations. The novel use of mussels in drinking water treatment was investigated by placing mussels in large flow-through tanks at Coppermills drinking water treatment plant (operated by Thames Water). Mussels reduced the concentration of chlorophyll a and suspended solids in the water flowing through tanks, and increased sedimentation through the production of faeces and pseudofaeces. Therefore mussels behaved as flocculators, and could be used in the early stages of drinking water treatment. In order to assess the feasibility of producing the large numbers of mussels needed for their use as biofilters, freshwater mussels were cultured in the laboratory. Juveniles of Anodonta anatina and A. cygnea were successfully reared for over a year, and reached 14mm in length (mean = 11.3mm, n = 17) with 20% survival. Unio pictorum and Pseudanodonta complanata were also reared for 274 and 100 days respectively, although they had lower survival and growth. The apparatus used in these rearing attempts was small and inexpensive, and could be scaled up to produce the required number of mussels for their use as biofilters. Additionally, the rearing of P. complanata is vital for the conservation of this rare mussel species, and offers the first opportunity to study its juvenile morphology and habitat requirements.
Mussels as a tool for mitigation of nutrients in the marine environment
Marine Pollution Bulletin, 2014
Long-line mussel farming has been proposed as a mitigation tool for removal of excess nutrients in eutrophic coastal waters. A full-scale mussel farm optimized for cost efficient nutrient removal was established in the eutrophic Skive Fjord, Denmark where biological and economic parameters related to nutrient removal was monitored throughout a full production cycle (1 yr). The results showed that it was possible to obtain a high area specific biomass of 60 t WW ha À1 eqvivalent to a nitrogen and phosphorus removal of 0.6-0.9 and 0.03-0.04 t ha À1 yr, respectively. The analysis of the costs related to establishment, maintenance and harvest revealed that mussel production optimized for mitigation can be carried out at a lower cost compared to mussel production for (human) consumption. The costs for nutrient removal was 14.8 € kg À1 N making mitigation mussel production a cost-efficient measure compared to the most expensive land-based measures.
Fish & Shellfish Immunology, 2014
Deleterious effects on health and fitness are expected in mussels chronically exposed to sewage water pollution. Diplodon chilensis inhabiting SMA, an area affected by untreated and treated sewage water, shows increased hemocyte number and phagocytic activity, while bacteriolytic and phenoloxidase activities in plasma and reactive oxygen species production in hemocytes are lower compared to mussels from an unpolluted area (Yuco). There are not differences in cell viability, lysosomal membrane stability, lipid peroxidation and total oxygen scavenging capacity between SMA and Yuco mussels' hemocytes. Energetic reserves and digestive gland mass do not show differences between groups; although the condition factor is higher in SMA than in Yuco mussels. Gills of SMA mussels show an increase in mass and micronuclei frequency compared to those of Yuco. Mussels from both sites reduce bacterial loads in polluted water and sediments, improving their quality with similar feeding performance. These findings suggest that mussels exposed to sewage pollution modulate physiological responses by long-term exposure; although, gills are sensitive to these conditions and suffer chronic damage. Bioremediation potential found in D. chilensis widens the field of work for remediation of sewage bacterial pollution in water and sediments by filtering bivalves.
Journal of the World Aquaculture Society, 2001
Abstruct.-The freshwater mussel Ellipiio complunciiu was provided water containing green algae and cyanobacteria delivered from the Partitioned Aquaculture System (PAS) at eight flow rates to determine algal filtration rates as mg of particulate organic carbon ( P 0 C ) k g wet tissue weight per h. The dominant taxon in cyanobacterial waters was Microcystis while the dominant taxa in green algal waters were Scenedesmus and Ankistrodesmus. The cell counts of Scenedesmus and Ankisrrodesmus were the only algal taxa that were significantly different between the incoming water and water filtered by mussels. Filtration rates of POC obtained from green algal water were significantly greater than from cyanobacteria-dominated waters at all flow rates. A significant increase in mean filtration rate was observed as flow rates increased. The filtration rate of green algae increased as POC concentration increased, peaking at 28 mg C/L. A maximum filtration rate was not observed with cyanobacterial waters.
The use of mussels for mitigating the noxious effect of phytoplankton spring blooms on farmed fish
Aquacultural Engineering, 2015
The possibility of using the natural biofiltration power of blue mussels (Mytilus edulis, 0.37 ± 0.08 g ind −1 dry weight) to dampen the potential detrimental effect of phytoplankton blooms on juvenile farmed sea bass (Dicentrarchus labrax) was tested in a fish farm during a 35-day mesocosm experiment. Mussel effective clearance rates averaged 41.15 ± 14.19 m 3 h −1 and led to a 6.3-13.1-fold reduction of the phytoplankton abundance as well as comparable decreases in chlorophyll a and turbidity. This improvement in seawater quality significantly enhanced fish physiological performances: weight-based growth rates were significantly higher (2.87 ± 0.43% d −1 ) compared to control exposed to non-filtered (bulk) seawater (2.55 ± 0.44% d −1 ). The same observation holds for the Fulton condition index and the metabolic activity (RNA:DNA ratio). For fish reared in bulk seawater, diatoms embedded in gills (Rhizosolenia imbricata, Thalassiosira sp.) and mucus overproduction indicated a stress (i.e. mechanical damages) induced by phytoplankton exposure which, in turn, may have affected fish energy balance. The use of mussels as a satisfying mitigation tool reducing phytoplankton bloom impacts is discussed with regard to phytoplankton bloom magnitude and ashore marine fish farming in coastal ecosystems.
Freshwater Biology, 1981
ElUptio complanata in this softwater lake ecosystem. Density (0.032 adults m-). biomass (52 mg m"-as dry organic matter) and annual production (6.4 mg m-as dry organic matter) of the mussel population are low when compared with results from other studies, corresponding with the general observation that mussels are scarce in soft, oligotrophic waters. We reject the traditional view that the low mussel density is a result of low calcium concentrations in Mirror Lake, and propose that mussel populations may be regulated by a scarcity of appropriate Hsh hosts in unproductive lakes. ElUptio complanata is probably not important in the metabolism or biochemistry of the Mirror Lake ecosystem.
Freshwater Biology, 2009
1. We investigated the role of algal composition on pumping, clearance, assimilation, pseudofaeces and faeces production, feeding time budgets, and condition of zebra mussels from spring to autumn at two sites in Saginaw Bay (Lake Huron) and one site in western Lake Erie. Size-fractioned chlorophyll was used to distinguish between feeding on small (<53 lm) and large (>53 lm) size fractions, and mussel feeding behaviour was quantified by video observations. 2. Mussel pumping, clearance and assimilation rates varied among sites, particularly during summer, when phytoplankton composition varied considerably among sites. Lowest values were seen at the inner-bay site of Saginaw Bay, low to moderate values at the outer-bay site of Saginaw Bay, and high values at the Lake Erie site. Clearance, pumping and assimilation rates were all highly positively correlated (R 2 = 0.76) with per cent contribution of flagellates to total algal biomass and negatively correlated with per cent of Microcystis aeruginosa (R 2 = 0.63). The negative effects on pumping rate (as determined by clearance rate on the <53 lm fraction) of Microcystis, which occurred in the >53 lm fraction, could be mitigated by the presence of flagellates in the <53 lm fraction. 3. Visual observations of mussel feeding showed evidence for poor seston quality during summer negatively affecting feeding rates. High faeces production during times of low assimilation rate was suggestive of poor assimilation efficiency and ⁄ or viable gut passage of grazing resistant algae. Long periods of time not filtering by the mussels during some Microcystis blooms and lack of production of a filtering current during one experiment were suggestive of intoxication from microcystin or other secondary compounds. 4. Clearance and feeding rates of the mussels in Saginaw Bay were high during spring and autumn and very low in summer, particularly at the inner-bay site. Condition of the mussels (mass : length ratio) was highest in spring and lowest during summer. This seasonal variation probably reflected high food assimilation rate during autumn and spring and low assimilation rate and reproduction during summer. The condition of mussels throughout the year was higher at the outer-bay than the inner-bay site, reflecting better feeding conditions at the former. Mussel selective feeding may have been responsible for the poor quality of food at the inner bay site; therefore, we postulate that a regime shift in phytoplankton composition promoted by the mussels fed back into lowered condition of the mussels.
Impact of the invasive golden mussel (Limnoperna fortunei) on phytoplankton and nutrient cycling
Aquatic Invasions, 2012
In order to evaluate the effects of the golden mussel Limnoperna fortunei on phytoplankton density and composition and nutrient recycling we conducted a 24 h filtration experiment in Río Tercero Reservoir (Argentina) using four 400 L mesocosms, two of them stocked with 1700-1800 adult mussels each, and two controls (without mussels). Nutrient concentrations and phytoplankton composition and density were evaluated at 0, 3, 6, 12, and 24 h. Estimated filtration rates were 1.48-3.14 mL mg DW -1 h -1 . Grazing pressure by the mussel was not associated with algal taxonomy or cell size. After 24 h, L. fortunei removed 84% of the particulate nitrogen, and 49% of the particulate phosphorus. Nutrient regeneration was very significant as well: ammonium was produced at a rate of 3 μM NH 3 g DW -1 h -1 , whereas production of phosphates was 0.42 μM PO 4 g DW -1 h -1 . It is concluded that the impact of L. fortunei on phytoplankton and nutrient cycling can be as significant as that reported for another invasive bivalve -the zebra mussel Dreissena polymorpha in Europe and North America, but the overall effect of this impact on the biota may differ strongly under different environmental settings.