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The choice of an appropriate index to adequately describe the efficiency of pre-ingestive organic material selection is important for modelling the material flux within the suspension feeding process. Recently, a new selection efficiency index was suggested by Zemlys et al. (2003) which simplifies the quantification of the selection activity. A simple equation with interpretable parameters calculates the selection efficiency index using literature values of uptake rate and food quality. This analysis suggests the possibility of developing more general and biologically interpretable models.

Functional relationships between environmental variables, the biodeposition and clearance rates of Dreissena polymorpha and Mytilus edulis were estimated in the northern Baltic Sea. The biodeposition and clearance of the bivalves increased with ambient temperature. In more eutrophicated regions biodeposition and clearance rates increased curvilinearly with ambient concentrations of chlorophyll a and leveled off at high food concentrations. In less eutrophicated conditions a linear model gave the best fit suggesting that saturation level was not obtained. Additional variation in the biodeposition and clearance was explained by the interaction of water temperature, current velocity and chlorophyll a . Salinity had a significant effect on the biodeposition and clearance of D. polymorpha . The population of suspension-feeders cleared daily on average from 3 to 2426% of overlaying water in the littoral area constituting an important sink for primary production.

Bivalve suspension-feeders are considered to be keystone herbivores in many estuarine ecosystems. However, bivalves can also feed upon organisms that belong to the microzooplankton and on mesozooplankton. Laboratory experiments showed that nauplii of the copepod Temora longicornis were filtered by mussels at the same rate as algae. Adult T. longicornis were also susceptible to filtration by mussels and oysters, but at a lower rate. Mesocosm experiments compared plankton dynamics in systems with and without mussels. Biomass of diatoms, heterotrophic dinoflagellates and copepods was strongly reduced in the presence of mussels. Some components of the microbial food web, like ciliates and Phaeocystis , did not show a significant effect, due to cascading effects of declining copepod abundance. It is suggested that in the presence of mussels, the pelagic food web may be shifted towards a more dominant microbial food web.

Motile suspension-feeders are defined as macroinvertebrates, fishes, and mammals that strain multiple small particles from the water column during each feeding event. Motile suspension-feeders include some of the most economically and ecologically important species in estuarine, coastal, and open ocean ecosystems. Major fisheries are based on fishes such as anchovies, herrings, and mackerels that feed either mainly or partially on plankton. A variety of mechanisms are used to procure, extract, and select food particles, but particles are not selected and targeted individually. Selectivity for certain-size particles coupled with pulses of high abundance can have major effects on food web and ecosystem structure. Although benthic and motile suspension-feeders share many characteristics, two major distinctions can be identified. Unlike benthic species, water column based forms do not create the kind of stable structures that provide habitat and affect hydrography. A unique character of the motile forms is the ability to migrate, often over long distances, effectively transferring nutrients and energy and otherwise impacting multiple ecosystems.

Suspension-feeding fish influence several abiotic and biotic components of freshwater ecosystems. Amongst others, abiotic components include water transparency and retention of essential nutrients. Biotic effects include alterations to bacterioplankton, phytoplankton, zooplankton, phytobenthos and zoobenthos communities. Specifically, species composition, size structure, abundance and biomass of plankton communities can substantially be altered. In addition, growth, reproduction and life history of zooplankton can be changed. Examples of predation with cascading food-web effects or changes in nutrient dynamics largely via excretion are common. More often than not, it is the integrated impacts of the above factors that are responsible for the observed changes.

Suspension-feeding bivalves couple pelagic and benthic processes because they consume seston from the water column, and their biodeposits (feces and pseudofeces) settle on the sediment surface. Abundant stocks of bivalves can exert grazer control on phytoplankton, and this results in some nitrogen and phosphorus being regenerated to the water column as excreta and via microbial decomposition of biodeposits. Bivalve biodeposition, however, enhances net ecosystem losses of N and P via sediment burial and bacterially mediated, coupled nitrification-denitrification. Bivalve feeding also reduces turbidity and thereby increases light available for microphytobenthos. Although microphytobenthos may compete with nitrifying bacteria for N, potentially reducing coupled nitrification-denitrification, they retain N and P within sediments, further reducing net regeneration to the water column.

The simplest computational approach for estimating environmental carrying capacity (CC) for bivalve suspension-feeders is to compare the combined rate of filtration with rates of processes that contribute to food renewal. More realistic approaches are based on mathematical models that take into account complex sets of feedbacks, both positive and negative, whereby cultured organisms interact with ecosystem processes. Each of these methods requires spatial and temporal integrations. Yet densities of cultured animals and rates of ecological processes vary in space and time. We illustrate strong dependencies of estimated CC on the spatial and temporal scales chosen for associated integrations. Where food availability is the primary limitation upon CC, low resolution models may lead to overestimates of CC, when the potential for error increases in positive relation with the spatial scale resolved by a model. Considering both spatial and temporal integrations, we recommend a procedure to help evaluate the maximum appropriate scale for the situation at hand, thereby avoiding bias in estimates of CC stemming from any “dilution” of bivalve densities.

Erosion and dumping lead to increased concentrations of mineral particles in coastal waters. The muddy waters contained high concentrations of hydrophylic limestone particles 2–50 microns in diameter. Accumulations of these particles on the sea floor can lead to the mortality of benthic macro-organisms. Using laboratory experiments, we studied the impact of dumping from mines on the mobility, feeding and reproduction of the pelagic suspension-feeder Acartia . Increased particle load changes copepod locomotive and digestive processes. Nauplii production per female decreased about 7 times in waters polluted with mineral particles. A conceptual model of mineral particle concentration impact on suspension-feeders is presented.

Suspension-feeders are found in both pelagic and benthic systems. They function as an important part of an ecosystem's biomachinery that maintains water quality in aquatic systems. They remove suspended matter and excrete faeces, pseudofaeces and dissolved inorganic materials that contribute to nutrient cycling between the water column and the benthic habitats. Suspension-feeders are a key part of many natural aquatic remediation systems and they can decrease some negative anthropogenic impacts. Recent experiments are reported that demonstrate new effects of pollutants on the filtration rates of suspension-feeders.

The incidence of tumors in bivalve molluscs is receiving increased attention due to possible detrimental effects on harvested stocks. Although the etiology or causes of neoplasias remains unclear, pollution by carcinogenic agents is implicated in the heavily exploited littoral zones of coastal waters. In the Gulf of Gdańsk, southern Baltic Sea, a higher prevalence of the disorder was observed in infaunal facultative (deposit/suspension) feeders compared to epifaunal obligate suspension-feeders, providing a new behavioural aspect of the tumor. Recent studies also reveal a potential cause-and-effect relationship between sediment factors and the incidence of neoplasia across a range of environmental properties.