Presence Of Mussels Research Articles

Effects of mussels on nutrient cycling and bioseston in two contrasting tropical freshwater habitats

Freshwater mussels (Unionida) can strongly affect nutrient cycling in temperate ecosystems but data from the tropics is lacking. We quantified the effects of mussel filtration, excretion and biodeposition on nutrient and photosynthetic pigment concentrations in a tropical eutrophic lake and mesotrophic river, featuring one non-native and two native species, respectively. Changes in nutrient and pigment concentrations were measured over a 3 h period to assess effects on (1) the water column in field enclosures, and (2) water column and benthos combined in controlled laboratory experiments. In field enclosures in both systems, mussel density and biomass were significantly correlated with the magnitude of reduction in sestonic pigment concentrations. In laboratory experiments, presence of mussels led to reduced PO4 and increased TAN concentrations in both systems, lower combined sestonic and deposited pigment concentrations in the river but increases in the same in the lake. We conclude that excretion by mussels probably accelerated bioseston growth in both systems due to N-fertilisation, an effect that may be particularly common in tropical freshwaters, which are frequently N-limited. However, whilst river mussels reduced bioseston concentrations through rapid filtration, higher rates of N-excretion and/or deposition of undigested bioseston by lake mussels apparently resulted in a net increase of pigment concentrations.

Freshwater mussel abundance and species composition downstream of a large hydroelectric generating station

Freshwater mussels are a significant component of freshwater ecosystems and often make up the largest biomass within these systems. However, their habitat is often subject to impacts such as changes in water quality or hydraulic stressors related to dams. Using snorkelling surveys, this study identified the presence, relative abundance, and spatial distribution of freshwater mussels in the Saint John River downstream of the Mactaquac Generating Station. This study also characterizes, in a general sense, the different habitats supporting these mussel assemblages. The surveys found five of the 11 species that have been previously recorded in the whole Saint John River system. Additional surveys within the Saint John River watershed with increased search effort per site are needed to detect rare species. Species composition and relative abundance differed in surveyed reaches, which are characterized by discrete habitat conditions. No differences in species diversity were observed between surveyed reaches. Trends in species distribution are likely due to a changing substrate composition moving downstream from a sediment-starved reach in the tailrace area of the river, followed by a coarse/fine flow-sorted mixture in the island area to a nearly homogenous sandy substrate further downstream.

Metagenomic analysis of nitrogen-cycling genes in upper Mississippi river sediment with mussel assemblages.

We investigated the impact of native freshwater mussel assemblages (order Unionoida) on the abundance and composition of nitrogen‐cycling genes in sediment of an upper Mississippi river habitat. We hypothesized that the genomic potential for ammonia and nitrite oxidation would be greater in the sediment with mussel assemblages, presumably due to mussel biodeposition products, namely ammonia and organic carbon. Regardless of the presence of mussels, upper Mississippi river sediment microbial communities had the largest genomic potential for nitrogen fixation followed by urea catabolism, nitrate metabolism, and nitrate assimilation, as evidenced by analysis of nitrogen cycling pathway abundances. However, genes encoding nitrate and nitrite redox reactions, narGHI and nxrAB, were the most abundant functional genes of the nitrogen cycling gene families. Using linear discriminant analysis (LDA), we found nitrification genes were the most important biomarkers for nitrogen cycling genomic potential when mussels were present, and this presented an opposing effect on the abundance of genes encoding nitric oxide reduction. The genes involved in nitrification that increased the most were amoA associated with comammox Nitrospira and nxr homologs associated with Nitrospira. On the other hand, the most distinctive biomarkers of microbial communities without mussels were norB and nrfA, as part of denitrification and dissimilatory nitrate reduction to ammonium pathways, respectively. Ultimately, this research demonstrates the impact of native mollusks on microbial nitrogen cycling in an aquatic agroecosystem.

Effects of the Invasive Freshwater Mussel Limnoperna fortunei on Sediment Properties and Accumulation Rates

AbstractSince its introduction into South America around 1990, the freshwater bivalve Limnoperna fortunei (the golden mussel) has spread rapidly and is now a dominant component of the benthic and periphytic fauna in many rivers, lakes, and reservoirs. Sizable impacts of this nonindigenous species on nutrient recycling, plankton abundance and composition, and trophic relationships with fishes have been reported, but its effects on the sediments have received little attention. In this work, we use eighteen 20‐L flow‐through experimental units with and without mussels where changes in the mass and characteristics of the sediments accumulated throughout a yearly cycle in monthly, biannual, and annual intervals are analyzed. Experimental units with mussels yielded almost 2 times more sediments than units without mussels and contained significantly higher loads of organic matter and total N. Total P was not affected by the presence of mussels. Sediments accumulated in the biannual and annual experimental units agreed well with the yields of the monthly units, but the vertical stratification of organic matter, N, and P was unpatterned. Seasonal changes in the volume of total sediments, biodeposits, and their organic matter and N contents were positively associated with ambient water temperature and with intermediate (~150–250 NTU, nephelometric turbidity units) turbidity. Our results suggest that ecosystem‐wide modifications in the living conditions of the benthic epifaunal and infaunal organisms in waterbodies invaded by the mussel are likely significant, although variable locally, regionally, and across taxa.

Erodibility and transport behavior of dreissenid mussel deposits in an annular flume

Zebra mussels (Dreissena polymorpha) alter the transport dynamics and fate of particulate matter in aquatic systems by intercepting, retaining, and recycling suspended materials. This study examines the effect of particle processing by dressenids on the nature (grain size distribution, settling velocity, porosity and density) and transport properties (critical shear stress for erosion, erosion rates, and bed stability) of suspended particulate matter in lakes. The bed stability, erosion rate, and critical shear stress for erosion of dreissenid biodeposits were measured in an annular flume. The particle size distribution, settling rate, density, and porosity were measured to characterize the physical nature of the biodeposits. Materials studied in the flume include (1) a combination of biodeposits and surface sediments collected from dreissenid beds and (2) biodeposits harvested in a weir box populated with dreissenids. The settling rates of both biodeposit/sediment mixtures and pure biodeposits were lower than natural sediment in lacustrine environments. Erosion characteristics and transport properties of biodeposits were strongly influenced by bed age and the presence of mussels. Bed stability increased after 7 days, with a τcrit of 0.26 Pa compared to the 2- and 14-day consolidation periods (τcrit = 0.13 and 0.15 Pa), respectively. The observed changes in bed stability with bed age will modify the transfer of particulate materials to the offshore profundal zone as well as the rates and magnitudes of sediment-associated nutrients in the near shore zone. Biostabilization of surficial lake-bottom sediments impacted by mussel biodeposits may increase bed stability and reduce the export of particulate matter to the offshore environment. Further, well-developed communities of dreissedid mussels have an armoring effect on deposited sediment, which reduces remobilization of sediment and biodeposits. However, once eroded, the dreissedid modified deposits will likely be transported further due to their low-settling velocity.

Greater macroinvertebrate diversity and freshwater mussel density in meander margins of an Amazon river

AbstractMeanders are complex aquatic environments exhibiting different flow and sediment characteristics that influence macroinvertebrate distribution. Differences in macroinvertebrate composition, freshwater mussel density (mainly Castalia ambigua Lamarck, 1819) and habitat variables were investigated, using uni‐ and multivariate analyses, in two zones, the margin and thalweg, of the meanders of a 7‐km stretch of a morphologically unaltered tropical alluvial lowland river. Clear differences were found between meander zones, with greater taxonomic and functional diversity of macroinvertebrates and greater freshwater mussel densities in the meander margin. A total of 12 families of macroinvertebrates were exclusive to the meander margin, and macroinvertebrate indicators of zones were Philopotamidae and Leptoceridae (meander margin) and Chironomidae and Elmidae (meander thalweg). In the meander margin, there were no differences in macroinvertebrate abundance, and taxonomic and functional group diversity among areas with low, medium and high mussel density. Macroinvertebrate abundance did not vary between zones, but in both, abundance was associated with lower pH and higher electrical conductivity. Low shear velocity, which stabilises the river bed, high organic matter content and percentage silt in the meander margin were associated with higher taxonomic and functional macroinvertebrate diversity, as well as the presence of freshwater mussels. Natural unaltered meanders are spatially heterogeneous in both habitat and biodiversity and, similar to restored meanders, support greater macroinvertebrate taxonomic and functional diversity, as well as maintain freshwater mussel beds, mainly by stabilising the river bed. The meander margin may also be important for attracting mussel host fish that feed on macroinvertebrates and aid mussel dispersal. Thus, the meander margins, and other similar riparian habitats with low shear velocity, for example, side channels and pools, have potentially high conservation value and should be afforded due protection.

Regional Dispersal Influences Zooplankton Community Response to Dreissena polymopha Invasion

Aquatic systems are becoming increasingly susceptible to invasive species whereby local species are reduced in abundance and richness leading to changes in many food webs. Dispersal of species from surrounding lakes may provide a natural mechanism to increase local resistance by providing a diversity of locally adapted species to colonize affected communities. This study examined how zooplankton dispersal could potentially reduce the effects of the invasive zebra mussel, Dreissena polymorpha, on zooplankton community total abundance, species richness and diversity. Field experiments were conducted in 20 large tanks, with five replicates, to observe zooplankton community response to (1) the presence and absence of zebra mussels, and (2) the presence and absence of regional disperser zooplankton. Live regional zooplankton, from six surrounding lakes, were added fortnightly to dispersal treatments, while heat-killed zooplankton were added to no-dispersal treatments. All tanks were sampled for chlorophyll and zooplankton community samples prior to dispersal additions. Zooplankton were counted and identified as cladocerans and copepods (macrozooplankton), and rotifers (microzooplankton) to species. In the presence of mussels, chlorophyll was significantly depleted, reducing nutrient availability. All zooplankton richness and abundance decreased suggesting strong resource competition and direct predation by mussels. Dispersal did not affect macrozooplankton community structure, however, dispersal influenced the effect of zebra mussels on rotifers, further decreasing richness. This suggests species from the surrounding lakes may be highly competitive among local species, further proposing that regional species may influence zooplankton community structure and responses to zebra mussel invasion, but the effect is species dependent.

A mesocosm investigation of the effects of quagga mussels (Dreissena rostriformis bugensis) on Lake Michigan zooplankton assemblages

Abstract Dreissenid mussels are known to disrupt the base of the food web by filter feeding on phytoplankton; however, they may also directly ingest zooplankton thereby complicating their effects on plankton communities. The objective of this study was to quantify the effects of quagga mussel feeding on the composition and size structure of Lake Michigan zooplankton assemblages. Two mesocosm (six 946 L tanks) experiments were conducted in summer 2013, using quagga mussels and zooplankton collected near Beaver Island, MI, to examine the response of zooplankton communities to the presence and absence of mussels (experiment 1) and varying mussel density (experiment 2). Mesocosms were sampled daily and zooplankton taxa were enumerated and sized using microscopy and FlowCAM® imaging. In experiment 1, the presence of quagga mussels had a rapid negative effect on veliger and copepod nauplii abundance, and a delayed negative effect on rotifer abundance. In experiment 2, mussel density had a negative effect on veliger, nauplii, and copepodite abundance within 24 h. Multivariate analyses revealed a change in zooplankton community composition with increasing mussel density. Ten zooplankton taxa decreased in abundance and frequency as quagga mussel density increased: except for the rotifer Trichocerca sp., treatments with higher mussel densities (i.e., 1327, 3585, and 5389 mussels/m 2 ) had the greatest negative effect on small-bodied zooplankton (≤ 128 μm). This study confirms results from small-scale (≤ 1 L) experiments and demonstrates that quagga mussels can alter zooplankton communities at mesoscales (~ 1000 L), possibly through a combination of direct consumption and resource depletion.

Comparative impact of two glyphosate-based formulations in interaction with Limnoperna fortunei on freshwater phytoplankton

Although contamination and invasive species are two of the most relevant anthropogenic drivers affecting ecosystems, their joint impact on the environment has been poorly investigated. Glyphosate, directly or indirectly, contaminates freshwater systems which in turn may be invaded by the golden mussel Limnoperna fortunei. Under laboratory conditions, we studied the combined effect of technical-grade glyphosate, Roundup Max® and Glifosato Atanor®, in scenarios with and without L. fortunei, on phytoplankton from Salto Grande Reservoir (Uruguay River, Argentina). We expected that the effects of the interaction on phytoplankton and water quality would vary with the form of herbicide applied. The assay was conducted for 14days (Tf) using 3-L bottles as experimental units. Eight treatments were performed in triplicate: C: Control; M: mussel; G: technical-grade glyphosate acid; R: Roundup Max®; A: Glifosato Atanor®; MG: mussel+technical-grade glyphosate acid, MA: mussel+Glifosato Atanor® and MR: mussel+Roundup Max®. The active ingredient was applied at 6ppm. The dissipation of glyphosate in water was 1.5–2.6 times higher in presence of mussels. Treatments G and A showed an increase in phytoplankton abundance, mainly the cyanobacteria Microcystis spp. wich rised to 289% and 639% at Tf, respectively, relative to their values at Ti. Roundup Max® limited the growth of Microcystis spp., as its abundance decreased 59% relative to Ti. L. fortunei reduced phytoplankton abundances at Tf. Evenness increased significantly in M, MG, MR and MA, while it decreased in G, R and A relative to C. The interaction of factors produced a significant synergistic increase in periphyton; periphytic chlorophyll a concentration was 0.81±0.02μgcm−2 for MR; 0.09±0.02μgcm−2 for MA and 0.02±0.01μgcm−2 for MG. Limnoperna fortunei appeared as the driving force in the interaction. The assay described here allows for the rapid assessment of the impact of these types of agents on freshwater.

Influence of environmental factors and biogenic habitats on intertidal meiofauna

This study investigated the influence of physical and chemical conditions and biotic factors on the distribution and diversity of meiofauna in intertidal zone along a geographical gradient. At 11 sites along the Italian coast, we studied the concurring role of environmental variables, trophic resources and the presence of habitat-forming species (macroalgae vs. mussels) in controlling the meiofaunal communities. The increase of water temperature combined with local thermal conditions was associated with a decrease in nematodes and copepods, with a consequent decrease in meiofaunal abundance towards the south. However, the increase in salinity, as geographical gradient decreases, and local thermal conditions favoured the settlement of a greater number of taxa, influencing communities’ composition. The presence of macroalgae or mussels differently influenced the community structure of meiofauna on intertidal substrates and their response to environmental factors. From our results, the presence of macroalgae coverage appeared to reduce the impact of thermal stress on meiofauna and was associated with higher levels of meiofaunal diversity with respect to mussels. This work highlighted the importance of considering the interplay among biotic and abiotic factors, resulting in local combinations of environmental conditions, in order to understand the pattern of diversity and distributions of marine organisms.

Freshwater mussels (Anodonta anatina) reduce transmission of a common fish trematode (eye fluke, Diplostomum pseudospathaceum).

Recent results suggest that bivalves can play an important role in restraining the spread of various aquatic infections. However, the ability of mussels to remove free-living stages of macroparasites and reduce their transmission is still understudied, especially for freshwater ecosystems. We investigated the influence of the common freshwater mussel (Anodonta anatina) on the transmission of a trematode (eye fluke, Diplostomum pseudospathaceum), which frequently infects fish in farms and natural habitats. In our experiments, mussels caused a significant decrease (P < 0·001) in the abundance of trematode free-living stages, from 6520 to 1770 cercariae L-1 on average (about 4-fold in 2 h). Individual clearance rates of mussels were 0·6‒3·7 L per hour (mean 1·9). These tests were followed by experimental infections of rainbow trout (Oncorhynchus mykiss) with different doses of D. pseudospathaceum cercariae in the presence or absence of mussels. Exposure of fish to cercariae in the presence of mussels significantly (P < 0·05) reduced the infection intensities in fish (by 30-40%) at all exposure doses. Our results indicate that freshwater bivalves can markedly reduce local cercariae densities and could be useful in mitigation of trematodoses harmful to fish farming.

Trends in body condition of smallmouth bass and northern pike (1982–2013) following multiple ecological perturbations in the St. Lawrence River

Body condition indices can be used to investigate fish response to biological or environmental change. We used quantile regression to analyze a 32-year weight–length data set (1982–2013) for smallmouth bass (Micropterus dolomieu) and northern pike (Esox lucius) from the St. Lawrence River to examine changes in condition (weight-at-length) during three ecologically distinct time periods. Condition of both species varied among time periods, with smallmouth bass experiencing greater proportional changes than northern pike. Smallmouth bass weight-at-length was greatest during 2005–2013 and lowest during 1982–1992. Northern pike weight-at-length was greatest during 2005–2013 for quantiles ≥0.5, similar between the 1982–1992 and 2005–2013 time periods for lower quantiles, and lowest during 1993–2004. The most likely weight–length model for smallmouth bass included terms for length, presence of round goby (Neogobius melanostomus), presence of dreissenid mussels, and an interaction between length and dreissenid mussels (wi = 0.93). The most likely model for northern pike included terms for length, presence of round goby, presence of dreissenid mussels, water temperature, conspecific abundance, and sex (wi = 0.56). Invasive species and environmental change related to invasive species have altered the condition of smallmouth bass and northern pike in the St. Lawrence River.

Differential effects of adult mussels on the retention and fine-scale distribution of juvenile seed mussels and biofouling organisms in long-line aquaculture

AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 9:239-256 (2017) - DOI: https://doi.org/10.3354/aei00230 Differential effects of adult mussels on the retention and fine-scale distribution of juvenile seed mussels and biofouling organisms in long-line aquaculture Paul M. South1,2,*, Oliver Floerl1, Andrew G. Jeffs2 1Cawthron Institute, 98 Halifax Street East, Nelson 7010, New Zealand 2Institute of Marine Science, University of Auckland, Private bag 92019, Auckland, New Zealand *Corresponding author: paul.south@cawthron.org.nz ABSTRACT: The majority of juvenile seed mussels are lost in aquaculture production. Understanding the causes of the losses of seed mussels is critical to reducing uncertainties in mussel aquaculture production. One major cause of loss appears to be the secondary settlement behaviour of mussels, which is thought to be a behavioural process by which larger juveniles can safely recruit among adults. This implies that once a juvenile mussel has settled among adults, there is either some impetus to remain or other positive interactions that promote increased survival. In this study, 2 densities (5 and 20 per 45 cm experimental rope) of adult green-lipped mussels Perna canaliculus were deployed alongside juvenile seed mussels to test whether this enhanced the retention of the juveniles in a typical suspended culture. Adult shells were also deployed to ascertain whether any effects were due to the physical presence of the mussels or the influence of their biological functioning. The presence of adult mussels or shells did not increase the retention of juvenile P. canaliculus, but small-scale movements of juveniles were increased by the addition of 20 live adult mussels per experimental rope. However, the presence of adult mussels and mussel shells on experimental ropes greatly increased the abundance of biofouling organisms. While the addition of live adult mussels or shells failed to provide a simple tool for increasing retention of seed mussels on aquaculture lines, they offer new insights into the identity and ecology of key biofouling organisms that can be problematic in mussel aquaculture production. KEY WORDS: Mussel retention · Secondary settlement · Green-lipped mussel · Perna canaliculus · Mytilus galloprovincialis · Recruitment Full text in pdf format PreviousNextCite this article as: South PM, Floerl O, Jeffs AG (2017) Differential effects of adult mussels on the retention and fine-scale distribution of juvenile seed mussels and biofouling organisms in long-line aquaculture. Aquacult Environ Interact 9:239-256. https://doi.org/10.3354/aei00230 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 9. Online publication date: July 26, 2017 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2017 Inter-Research.

Influence of invasive quagga mussels, phosphorus loads, and climate on spatial and temporal patterns of productivity in Lake Michigan: A biophysical modeling study

AbstractWe applied a three‐dimensional biophysical model to Lake Michigan for the years 2000, 2005, and 2010 to consider the mechanisms controlling spatial and temporal patterns of phytoplankton abundance (chlorophyll a) and lake‐wide productivity. Model skill was assessed by comparison to satellite‐derived Chl a and field‐measured water quality variables. We evaluated model sensitivity to scenarios of varying mussel filter feeding intensity, tributary phosphorus loads, and warm vs. cool winter‐spring climate scenarios. During the winter‐spring phytoplankton bloom, spatial patterns of Chl a were controlled by variables that influenced surface mixed layer depth: deep mixing reduced net phytoplankton growth through light limitation and by exposing the full water column to mussel filter feeding. Onset of summer and winter stratification promoted higher surface Chl a initially by increasing mean light exposure and by separating the euphotic zone from mussels. During the summer stratified period, areas of relatively high Chl a were associated with coastal plumes influenced by tributary‐derived nutrients and coastal upwelling‐downwelling. While mussels influenced spatial and temporal distribution of Chl a, lake‐wide, annual mean primary production was more sensitive to phosphorus and warm/cool meteorology scenarios than to mussel filter feeding scenarios. Although Chl a and primary production declined over the quagga mussel invasion, our results suggest that increased nutrient loads would increase lake‐wide productivity even in the presence of mussels; however, altered spatial and temporal patterns of productivity caused by mussel filter feeding would likely persist.

Long-term changes in a Ligurian infralittoral community (Mediterranean Sea): A warning signal?

Recently, the Mediterranean littoral benthic communities suffered significant changes in their structure and composition, due to several natural and anthropogenic stresses. Also the Ligurian Sea has witnessed in several episodes (surface water warming, benthic mucilage developments, etc.) linked to the climate change that have influenced the structure of the benthic communities. In order to evaluate possible changes inside the benthic upper infralittoral community (4–7 m depth) living along the southern cliff of the Portofino MPA, sets of macro-photographs, realized in 2002–2003 and repeated 10 years later (2013), were analysed. The community structure, diversity, and species abundance were studied in 9 stations placed in three different localities (Ca’dell’Oro Bay, Punta Chiappa Point and St Fruttuoso Bay) at different levels of protection, although considered potentially affected only by natural stressors and not by direct human impacts.Over 10-years, a significant change in the macroalgal coverage and composition was observed in all considered stations and localities, with a reduction of the habitat complexity, being the frondose and habitat-forming macroalgae (Fucales, Dyctiotales) significantly decreased. In contrast, as regards the sessile zoobenthos, there has been an increase of branched bryozoans and a drop in the presence of barnacles and mussels. A significant emergence of some alien species (Asparagopsis armata,Caulerpa cylindraceaand Paraleucilla magna) linked to warmer waters was recorded too.In conclusion, the benthic upper infralittoral community (4–7 m depth) of the Portofino MPA seems to have being influenced by several climatic large-scale events that occurred in recent years in the Ligurian Sea and the change of its structural composition could be considered as a warning signal.

Factors influencing biodeposit production by the New Zealand freshwater mussel Echyridella menziesii

ABSTRACTLaboratory experiments on the New Zealand freshwater mussel Echyridella menziesii were used to investigate the short-term effects (7–8 days) of food type on rates of biodeposition and benthic substrate respiration. Post-feeding biodeposition rates ranged from 0.34 to 1.52 mg g−1 h−1 (mean = 0.50 mg g−1 h−1) and were unaffected by the addition of toxin-producing Microcystis. Addition of suspended sediment (30 mg L−1) visibly altered substrate composition, and increased total and inorganic biodeposit production rates by 24–33% compared to mussels fed commercial phytoplankton stock. Biodeposition rates of mussels in lake bed substrates were 38% higher than those in silica sand for identical feeding regimes, suggesting that a significant proportion of material produced in this experiment could have been derived from feeding on organic matter in the lake bed sediments. Respiration rates were higher in treatments with Microcystis but were unaffected by the presence of mussels. This laboratory study suggests that biodeposition by E. menziesii is resilient to short-term exposure to Microcystis, and highlights the ability of mussels to alter benthic substrate composition by incorporating suspended sediment into substrates.

Municipal wastewater treatment plant effluent-induced effects on freshwater mussel populations and the role of mussel refugia in recolonizing an extirpated reach

Global human population and urbanization continually increase the volume of wastewater entering aquatic environments. Despite efforts to treat these effluents, they contribute a diverse suite of substances that enter watersheds at concentrations that have the potential to elicit adverse effects on aquatic organisms. The relationship between wastewater treatment plant (WWTP) effluent exposure and biological responses within aquatic ecosystems remains poorly understood, especially at the population level. To examine the effect of WWTP effluents on sentinel invertebrates, freshwater mussels were assessed in the Grand River, Ontario, in populations associated with the outfall of a major WWTP. This watershed, within the Laurentian Great Lakes basin, has a diverse community of twenty-five species of mussels, including nine Species at Risk, and is representative of many habitats that receive WWTP effluents regionally as well as globally. Surveys were conducted to assess the presence and species richness of freshwater mussels. In total, 55 sites downstream of the WWTP were examined using timed visual searches with one or 2 h of effort spent searching 100 m segments. Although seven species of mussels were found in moderate abundance (mean of 8 mussels per hour of searching across 2 sites) upstream of the WWTP outfall, no live mussels were observed for 7.0 km downstream of the WWTP. Long-term water quality monitoring data indicate that ammonia and nitrite concentrations along with large seasonal declines in diel dissolved oxygen were associated with the extirpation of mussels downstream of the WWTP. The first live mussels found downstream were below the confluence with a major tributary indicating that in addition to an improvement in water quality to a state that enables mussels (and/or their fish hosts) to survive, a nearby mussel refuge may have facilitated the recolonization of the depauperate WWTP-impacted zone.

Application of OEPA-Produced Biotic Indices and Physical Stream Measurements to Assess Freshwater Mussel (Unionidae) Habitat in the Upper Mahoning River, Ohio

Freshwater mussels continue to experience declines in population numbers in response to changing environments. Identifying aspects of the environment associated with the presence and abundance of mussels in small streams is challenging where past records are minimal. Thus, we sought to produce models of habitat favoring mussel species richness and abundance in the upper Mahoning River using data collected in 2 ways: (1) surveying sites deemed as suitable habitat via observation and (2) surveying existing Ohio Environmental Protection Agency (OEPA) sites used to evaluate water quality and aquatic life through biotic indices. Detailed physical measurements were added at each survey site. Surveys identified 963 freshwater mussels of 11 species. The more-forested Eagle Creek contained an abundant mussel assemblage compared to the rest of the Upper Mahoning River, yet this stream was still dominated by just 1 common species, Lampsilis siliquoidea (Fatmucket). Drainage area alone correlated with mussel richness and abundance, but a complex model of multiple characteristics provided equivalent predictive power to assess how variation in environmental components may enhance the likelihood of mussel presence. The OEPA composite qualitative habitat evaluation index, which encompasses substrate, instream cover, channel morphology, riparian zone, pool quality, and map gradient, also was indicative of greater mussel diversity.

Exploration of the phycoremediation potential of Laminaria digitata towards diflubenzuron, lindane, copper and cadmium in a multitrophic pilot-scale experiment

The presence of contaminants in aquatic ecosystems can cause serious problems to the environment and marine organisms. This study aims to evaluate the phycoremediation capacity of macroalgae Laminaria digitata for pesticides (diflubenzuron and lindane) and toxic elements (cadmium and copper) in seawater in the presence or absence of mussels. The photosynthetic activity was monitored in the macroalgae to assess its “physiological status”. The results showed that the presence of algae decreased diflubenzuron concentration in mussels by 70% after 120 h of exposure. Additionally, this macroalgae was efficient to reduce lindane, Cu and Cd in seawater; even though it not was able to reduce these contaminants in mussels. The studied pollutants did not affect the physiological status of macroalgae. This study reveals that the application of phycoremediation with macroalgae can be an useful and effective mitigation strategy to remove/decrease contaminant levels from the aquatic environment.

In situ biodeposition measurements on a Modiolus modiolus (horse mussel) reef provide insights into ecosystem services

Horse mussel (Modiolus modiolus) shellfish reefs are a threatened and declining habitat in the North East Atlantic and support high levels of biodiversity. Shellfish can influence the surrounding water column and modify the quality of material that reaches the seabed by filtering water, actively depositing particles and changing the benthic boundary layer due to surface roughness. In the present study M. modiolus biodeposition was measured in a field location for the first time. The results show that M. modiolus enhance sedimentation and contribute to the downward flux of material to the seabed. Approximately 30% of the total sediment deposition was attributed to active filter feeding and overall, the presence of horse mussels enhanced deposition two fold. The results are discussed in terms of the potential for horse mussel reefs to provide ecosystem services to society, through functions such as benthopelagic coupling and sediment stabilisation. Highlighting the societal benefits supplied by marine habitats can help prioritise conservation efforts and feed into the sustainable management of coastal water bodies.