Monitoring bay-scale ecosystem changes in bivalve aquaculture embayments using flow cytometry.

Bay-scale empirical evaluations of how bivalve aquaculture alters plankton composition, and subsequently ecological functioning and higher trophic levels, are lacking. Temporal, inter- and within-bay variation in hydrodynamic, environmental, and aquaculture pressure complicate plankton monitoring design to detect bay-scale changes and inform aquaculture ecosystem interactions. Here, we used flow cytometry to investigate spatio-temporal variations in bacteria and phytoplankton (< 20 μm) composition in four bivalve aquaculture embayments.

Discharge of ballast residual sediments during de-ballasting procedures: A more realistic estimate of propagule pressure.

Ship ballast residual sediments are an important vector of introduction for non-indigenous species. We evaluated the proportion of residual sediments and associated organisms released during de-ballasting operations of a commercial bulk carrier and estimated a total residual sediment accumulation of ∼13 t, with accumulations of up to 20 cm in some tank areas that had accumulated over 11 years. We observed interior hull-fouling (anemones, hydrozoans, and bryozoans) and high abundances of viable invertebrate resting stages and dinoflagellate cysts in sediments.

Reconciling Coulter Counter and laser diffraction particle size analysis for aquaculture monitoring.

The disaggregated inorganic grain size (DIGS) of bottom sediment analyzed with a Coulter Counter (CC) has been used to show that the fraction of sediment deposited in flocs (floc fraction) increased in both the near and far field after the introduction of open cage salmon aquaculture, altering benthic habitat and species composition. As a result, DIGS was identified as a potential indicator of regional environmental changes due to aquaculture. Laser diffraction is an attractive alternative to the CC because of its greater efficiency and larger size range.

Using a metabolomics approach to investigate the sensitivity of a potential Arctic-invader and its Arctic sister-species to marine heatwaves and traditional harvesting disturbances.

Coastal species are threatened by fishing practices and changing environmental conditions, such as marine heatwaves (MHW). The mechanisms that confer tolerance to such stressors in marine invertebrates are poorly understood. However, differences in tolerance among different species may be attributed to their geographical distribution.

An integrative perspective on fish health: Environmental and anthropogenic pathways affecting fish stress.

Multifactorial studies assessing the cumulative effects of natural and anthropogenic stressors on individual stress response are crucial to understand how organisms and populations cope with environmental change. We tested direct and indirect causal pathways through which environmental stressors affect the stress response of wild gilthead seabream in Mediterranean costal lagoons using an integrative PLS-PM approach. We integrated information on 10 environmental variables and 36 physiological variables into seven latent variables reflecting lagoons features and fish health.

Relationship between in feed drugs, antibiotics and organic enrichment in marine sediments at Canadian Atlantic salmon aquaculture sites.

The presence of in-feed anti-sea lice drugs and their relationship with organic enrichment is poorly understood in sediment surrounding salmon farms. Using data from an aquaculture monitoring program (2018-2020), we describe this relationship at ten sites in four Canadian provinces. Three anti-sea lice pesticides (lufenuron, teflubenzuron, emamectin benzoate and metabolite desmethyl emamectin benzoate), and one antibiotic (oxytetracycline) were detected.

Arctic marine forest distribution models showcase potentially severe habitat losses for cryophilic species under climate change.

The Arctic is among the fastest-warming areas of the globe. Understanding the impact of climate change on foundational Arctic marine species is needed to provide insight on ecological resilience at high latitudes. Marine forests, the underwater seascapes formed by seaweeds, are predicted to expand their ranges further north in the Arctic in a warmer climate.

Trace Metal Residues in Marine Mussels: A Global Survey.

Pressures from anthropogenic activities are causing degradation of estuarine and coastal ecosystems around the world. Trace metals are key pollutants that are released and can partition in a range of environmental compartments, to be ultimately accumulated in exposed biota. The level of pressure varies with locations and the range and intensity of anthropogenic activities.

Assessing trace-elements as indicators of marine finfish aquaculture across three distinct Canadian coastal regions.

Several trace-elements have been identified as indicators of finfish aquaculture organic enrichment. In this study, sediment sampling at finfish farms was completed as part of an Aquaculture Monitoring Program in three distinct Canadian regions. Despite diverse datasets, multivariate analyses show a consistent clustering of known direct (Cu and Zn) and indirect (Cd, Mo and U) tracers of aquaculture activities with sediment organic matter (OM) and/or total dissolved sulfides concentrations.

Environmental stressors, complex interactions and marine benthic communities' responses.

The increasing number and diversity of anthropogenic stressors in marine habitats have multiple negative impacts on biological systems, biodiversity and ecosystem functions. Methods to assess cumulative effects include experimental manipulations, which may identify non-linear responses (i.e.

What and where? Predicting invasion hotspots in the Arctic marine realm.

The risk of aquatic invasions in the Arctic is expected to increase with climate warming, greater shipping activity and resource exploitation in the region. Planktonic and benthic marine aquatic invasive species (AIS) with the greatest potential for invasion and impact in the Canadian Arctic were identified and the 23 riskiest species were modelled to predict their potential spatial distributions at pan-Arctic and global scales. Modelling was conducted under present environmental conditions and two intermediate future (2050 and 2100) global warming scenarios.

Consumption of organic wastes from coastal salmon aquaculture by wild decapods.

Rock crab Cancer irroratus and American lobster Homarus americanus are important commercial species in coastal areas where intensive salmon aquaculture occurs in eastern Canada. Such aquaculture releases organic wastes, especially feed waste (i.e.

Changes in infaunal assemblage structure influence nutrient fluxes in sediment enriched by mussel biodeposition.

Although many studies have described the influence of bivalve aquaculture on the benthic environment, effects on benthic functional diversity are poorly known, as are links with ecosystem processes. We investigated the response of a benthic ecosystem in terms of taxonomic and functional diversity (infauna >500 μm), biogeochemical indicators (organic matter content, redox potential, sulfides level, bacteria) and metabolism (nutrient fluxes), subjected to various levels of mussel biodeposition as a general model of organic enrichment. Results show that local benthic conditions may recover fairly quickly depending on environmental conditions whereas modifications of the benthic community structure persist over a longer time scale with an impact on benthic ecosystem functioning.

Contribution of mussel fall-off from aquaculture to wild lobster Homarus americanus diets.

Anthropogenic subsidies to natural systems can influence the diet of mobile omnivore species and co-occurring species. This study assessed if fall-off from mussel aquaculture subsidized wild populations of mobile scavengers and predators, such as the commercially important lobster Homarus americanus. A Bayesian stable isotope-mixing model with parameters determined from the literature and from a 105 days laboratory feeding experiment was applied to wild lobsters to determine how important the various food sources were in these lobsters, especially mussel fall-off.

Ecological risk assessment of predicted marine invasions in the Canadian Arctic.

Climate change is impacting environmental conditions, especially with respect to temperature and ice cover in high latitude regions. Predictive models and risk assessment are key tools for understanding potential changes associated with such impacts on coastal regions. In this study relative ecological risk assessment was done for future potential introductions of three species in the Canadian Arctic: periwinkle Littorina littorea, soft shell clam Mya arenaria and red king crab Paralithodes camtschaticus.

Bioturbation activity of three macrofaunal species and the presence of meiofauna affect the abundance and composition of benthic bacterial communities.

Given concerns of increasing rates of species extinctions, the relationship between biodiversity and ecosystem functioning has become a major research focus over the past two decades. Many studies have shown that biodiversity per se (e.g.

Stabilizing mechanisms in a food web with an introduced omnivore.

Intraguild predation (IGP) is an omnivorous food web configuration in which the top predator consumes both a competitor (consumer) and a second prey that it shares with the competitor. This omnivorous configuration occurs frequently in food webs, but theory suggests that it is unstable unless stabilizing mechanisms exist that can decrease the strength of the omnivore and consumer interaction. Although these mechanisms have been documented in native food webs, little is known about whether they operate in the context of an introduced species.

Potential for Local Fertilization: A Benthocosm Test of Long-Term and Short-Term Effects of Mussel Excretion on the Plankton.

Mussel aquaculture has expanded worldwide and it is important to assess its impact on the water column and the planktonic food web to determine the sustainability of farming practices. Mussel farming may affect the planktonic food web indirectly by excreting bioavailable nutrients in the water column (a short-term effect) or by increasing nutrient effluxes from biodeposit-enriched sediments (a long-term effect). We tested both of these indirect effects in a lagoon by using plankton-enclosing benthocosms that were placed on the bottom of a shallow lagoon either inside of a mussel farm or at reference sites with no history of aquaculture.

Influence of intertidal recreational fisheries and 'bouchot' mussel culture on bivalve recruitment.

In coastal environments, fishing and aquaculture may be important sources of disturbance to ecosystem functioning, the quantification of which must be assessed to make them more sustainable. In the Chausey Archipelago, France, recreational fishing and commercial shellfish farming are the only two evident anthropogenic activities, dominated by bivalve hand-raking and 'bouchot' mussel culture, respectively. This study evaluates the impact of both activities on bivalve recruitment dynamics by comparing primary recruitment intensity (short-term effect) and recruitment efficiency (medium-term effect) by sampling bivalves in reference (undisturbed) and disturbed (i.

Metabolic activity and functional diversity changes in sediment prokaryotic communities organically enriched with mussel biodeposits.

This experimental microcosm study reports the influence of organic enrichments by mussel biodeposits on the metabolic activity and functional diversity of benthic prokaryotic communities. The different biodeposit enrichment regimes created, which mimicked the quantity of faeces and pseudo-faeces potentially deposited below mussel farms, show a clear stimulatory effect of this organic enrichment on prokaryotic metabolic activity. This effect was detected once a certain level of biodeposition was attained with a tipping point estimated between 3.

Dose-dependent response of a benthic system to biodeposition from suspended blue mussel (Mytilus edulis) culture.

This study reports the results of a field experiment using benthic mesocosms that examined dose-dependent effects of mussel biodeposition on the benthic environment. Mesocosms were placed in the natural sea bottom and subjected to one of eight levels of biodeposition (from 0 to 1400 mussels m⁻²). Most analyses indicated non-linear (i.

Disentangling invasion processes in a dynamic shipping-boating network.

The relative importance of multiple vectors to the initial establishment, spread and population dynamics of invasive species remains poorly understood. This study used molecular methods to clarify the roles of commercial shipping and recreational boating in the invasion by the cosmopolitan tunicate, Botryllus schlosseri. We evaluated (i) single vs.

Relationship between propagule pressure and colonization pressure in invasion ecology: a test with ships' ballast.

Increasing empirical evidence indicates the number of released individuals (i.e. propagule pressure) and number of released species (i.