Posts Tagged 'North Atlantic'

Impacts of climate change on aquaculture

Aquaculture is a key UK food production sector, and it is particularly economically important to rural coastal communities, and in the deprived urban areas where processing takes place (Alexander et al., 2014; UK MNMP, 2015). UK production value exceeds £590 million (Black and Hughes 2017), with £1.8bn turnover and 8800 jobs supported (Alexander et al., 2014), of this £1.4bn turnover and 8000 jobs are in Scotland, making aquaculture particularly relevant there. There is significant potential for aquaculture to develop further throughout the UK (Black and Hughes, 2017).

UK marine finfish aquaculture is dominated by the production off the west coast and islands of Scotland of Atlantic salmon, Salmo salar (156,025 tonnes in 2018; Munro, 2019), and a very small production from Northern Ireland. Freshwater salmon smolt production, for marine on-growing, is more widely distributed. Scottish marine production also includes rainbow trout (Onchorhyncus mykiss), sea (brown) trout (Salmo trutta) and halibut (Hippoglossus hippoglossus). In the past, cod (Gadus morhua) in Scotland, and sea bass (Dicentrarchus labrax) in Wales, were farmed. Recently, a major growth in production of lumpfish (Cyclopterus lumpus) and wrasse (various Labridae species) has occurred in Scotland (Munro, 2019), Wales (Anon, 2018) and England, for use as ‘cleaner fish’ to control sea lice on farmed salmon. The majority of marine salmonid aquaculture takes place in open-sea cages; 86% of freshwater salmonid smolts for marine on-growing are also produced in cages and so can be vulnerable to environmental conditions (Munro, 2019). Other smolts are produced in Recirculating Aquaculture Systems (RAS) that are protected against the environment, RAS are also used for production of other species such as lumpfish.

Bivalve-shellfish farming produces mussels (Mytilus edulis), oysters (Crassostrea gigas (Pacific) and Ostrea edulis (native), scallops (Pecten maximus, Chlamys opercularis) and clams (Ruditapes sp.). Mussels are the main farmed seafood product of Wales, Northern Ireland and England, and, for shellfish, Scotland. Pacific oyster is the second most-farmed shellfish, with minor production of the other bivalves. On-growing or ranching of prawn, lobster and crab and macroalgal farming remain small-scale (Capuzzo and McKie, 2016).

Continue reading ‘Impacts of climate change on aquaculture’

Clam feeding plasticity reduces herbivore vulnerability to ocean warming and acidification

Ocean warming and acidification affect species populations, but how interactions within communities are affected and how this translates into ecosystem functioning and resilience remain poorly understood. Here we demonstrate that experimental ocean warming and acidification significantly alters the interaction network among porewater nutrients, primary producers, herbivores and burrowing invertebrates in a seafloor sediment community, and is linked to behavioural plasticity in the clam Scrobicularia plana. Warming and acidification induced a shift in the clam’s feeding mode from predominantly suspension feeding under ambient conditions to deposit feeding with cascading effects on nutrient supply to primary producers. Surface-dwelling invertebrates were more tolerant to warming and acidification in the presence of S. plana, most probably due to the stimulatory effect of the clam on their microalgal food resources. This study demonstrates that predictions of population resilience to climate change require consideration of non-lethal effects such as behavioural changes of key species.

Continue reading ‘Clam feeding plasticity reduces herbivore vulnerability to ocean warming and acidification’

Water quality trends in Texas estuaries

Highlights

• Estuarine water quality data indicates regional “hot spots” of change in Texas.

• Symptoms of eutrophication were found in Galveston Bay, Oso Bay, and Baffin Bay.

• Increasing salinity was observed in estuaries of the central Texas coast.

• Decreasing pH was observed in estuaries of the central Texas coast.

Abstract

Coastal watersheds in Texas have experienced significant human population growth over the past several decades, yet there have been no comprehensive assessments of water quality trends in Texas estuaries. Here, analysis of historical estuarine water quality data indicates regional “hot spots” of change. Galveston Bay and Oso Bay, which have highly urbanized watersheds, currently exhibit symptoms of eutrophication. Symptoms of eutrophication were also found in the Baffin Bay-Upper Laguna Madre complex, which has a sparsely populated but agriculturally-intensive watershed. Increasing salinity was observed in estuaries of the central Texas coast and are attributed to long-term decreases in freshwater inflow. Another artifact of decreasing freshwater inflow is a reduction in the delivery of carbonate minerals to estuaries, which manifests as decreases in pH. With findings from this study, targeted studies can now be directed at the estuaries that are experiencing water quality degradation in order to guide future management efforts.

Continue reading ‘Water quality trends in Texas estuaries’

Hydrologic controls on CO2 chemistry and flux in subtropical lagoonal estuaries of the northwestern Gulf of Mexico

Estuaries are generally considered a source of CO2 to the atmosphere, although with significant uncertainties in magnitude and controlling factors between and within estuaries. We studied four northwestern Gulf of Mexico estuaries that experience extreme hydrologic conditions between April 2014 and February 2017 to determine the role of dry/wet cycle on estuarine CO2 system. Annual air–water CO2 flux ranged from 2.7 to 35.9 mol·C·m−2·yr−1; CO2 flux declined by approximately an order of magnitude along with declining river discharge. Episodic flooding made CO2 flux differ between dry (−0.7 to 20.9 mmol·C·m−2·d−1) and wet (11.6–170.0 mmol·C·m–2·d–1) conditions. During wet condition, increases in dissolved inorganic carbon (DIC) and total alkalinity (TA) significantly elevated CO2 degassing. Furthermore, ventilation of river‐borne CO2 strengthened degassing when estuaries became overwhelmingly river‐dominated. During flood relaxation, all estuaries experienced heightened productivity, evidenced by DIC and TA consumption in the mid‐salinity range (10–30). When prolonged drought led to hypersalinity (>36.5), biogeochemical and evaporative effects enhanced DIC and TA consumption and CO2 degassing. Due to flooding and high wind speeds, these estuaries were a strong CO2 source during spring and summer. Then they transitioned to a weak CO2 source or sink during the fall. Low temperatures further depressed CO2 efflux during winter except when a pulse of freshwater input occurred. This study demonstrates that changes in the hydrologic condition of estuaries, such as dry/wet cycle and river discharge gradient, will greatly alter air–water CO2 flux and estuarine contribution to the global carbon budget.

Continue reading ‘Hydrologic controls on CO2 chemistry and flux in subtropical lagoonal estuaries of the northwestern Gulf of Mexico’

Potential socioeconomic impacts from ocean acidification and climate change effects on Atlantic Canadian fisheries

Ocean acidification is an emerging consequence of anthropogenic carbon dioxide emissions. The full extent of the biological impacts are currently not entirely defined. However, it is expected that invertebrate species that rely on the mineral calcium carbonate will be directly affected. Despite the limited understanding of the full extent of potential impacts and responses there is a need to identify potential pathways for human societies to be affected by ocean acidification. Research on these social implications is a small but developing field. This research contributes to this field by using an impact assessment framework, informed by a biophysical model of future species distributions, to investigate potential impacts facing Atlantic Canadian society from potential changes in shellfish fisheries driven by ocean acidification and climate change. New Brunswick and Nova Scotia are expected to see declines in resource accessibility but are relatively socially insulated from these changes. Conversely, Prince Edward Island, along with Newfoundland and Labrador are more socially vulnerable to potential losses in fisheries, but are expected to experience relatively minor net changes in access.

Continue reading ‘Potential socioeconomic impacts from ocean acidification and climate change effects on Atlantic Canadian fisheries’

Blue mussel (Genus Mytilus) transcriptome response to simulated climate change in the Gulf of Maine

The biogeochemistry of the Gulf of Maine (GOM) is rapidly changing in response to the changing climate, including rising temperatures, acidification, and declining primary productivity. These impacts are projected to worsen over the next 100 y and will apply selective pressure on populations of marine calcifiers. This study investigates the transcriptome expression response to these changes in ecologically and economically important marine calcifiers, blue mussels. Wild mussels (Mytilus edulis and Mytilus trossulus) were sampled from sites spanning the GOM and exposed to two different biogeochemical water conditions: (1) present-day conditions in the GOM and (2) simulated future conditions, which included elevated temperature, increased acidity, and decreased food supply. Patterns of gene expression were measured using RNA sequencing from 24 mussel samples and contrasted between ambient and future conditions. The net calcification rate, a trait predicted to be under climate-induced stress, was measured for each individual over a 2-wk exposure period and used as a covariate along with gene expression patterns. Generalized linear models, with and without the calcification rate, were used to identify differentially expressed transcripts between ambient and future conditions. The comparison revealed transcripts that likely comprise a core stress response characterized by the induction of molecular chaperones, genes involved in aerobic metabolism, and indicators of cellular stress. Furthermore, the model contrasts revealed transcripts that may be associated with individual variation in calcification rate and suggest possible biological processes that may have downstream effects on calcification phenotypes, such as zinc-ion binding and protein degradation. Overall, these findings contribute to the understanding of blue mussel adaptive responses to imminent climate change and suggest metabolic pathways are resilient in variable environments.

Continue reading ‘Blue mussel (Genus Mytilus) transcriptome response to simulated climate change in the Gulf of Maine’

Air–sea CO2 exchange and ocean acidification in UK seas and adjacent waters

Ongoing anthropogenic emissions of carbon dioxide (CO2) into the atmosphere are driving a net flux of CO2 into the ocean globally, resulting in a decline in pH called ‘ocean acidification’. Here, we discuss the consequences of this for the seas surrounding the UK from a chemical perspective, focussing on studies published since the previous MCCIP review of ocean acidification research (Williamson et al., 2017). In this reporting cycle, the biological, ecological, and socio-economic impacts of ocean acidification are considered in more detail in separate accompanying MCCIP reviews.

The atmospheric CO2 concentration continues to increase due to human activities (Le Quéré et al., 2018), increasing the net flux of CO2 into the global ocean, including the North Atlantic and UK continental shelf seas. Such CO2 uptake has the desirable effect of reducing the rate of climate change, but the undesirable result of ocean acidification. Our understanding of the factors that drive high spatial and temporal variability in air-sea CO2 fluxes and seawater pH in UK waters has continued to improve, thanks to observational campaigns both across the entire North-West European continental shelf sea and at specific time–series sites. Key challenges for the future include sustaining time–series observations of near-surface marine carbonate system variables, and of the auxiliary parameters required for their interpretation (e.g. temperature, salinity, and nutrients); developing and deploying new sensor technology for full water-column profiles and pore waters in seafloor sediments; and increasing the spatial and temporal resolution of models sufficiently to capture the complex processes that dominate the marine carbonate system in coastal and shelf sea environments, along with improving how those processes are themselves simulated.

Continue reading ‘Air–sea CO2 exchange and ocean acidification in UK seas and adjacent waters’


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