Posts Tagged 'North Atlantic'

The economic impacts of ocean acidification on shellfish fisheries and aquaculture in the United Kingdom

Highlights

• We estimate both direct and economy-wide economic losses of shellfish production by 2100 in UK.
• Direct potential losses due to reduced shellfish production range from 14% to 28% of fishery NPV.
• Total loss to the UK economy from shellfish production and consumption range from £23 – £88 million.
• There are regional variations to economic losses due to different speceis and patterns of shellfish production and consumption.

Abstract

Ocean acidification may pose a major threat to commercial fisheries, especially those for calcifying shellfish species. This study was undertaken to estimate the potential economic costs resulting from ocean acidification on UK wild capture and aquaculture shellfish production. Applying the net present value (NPV) and partial equilibrium (PE) models, we estimate both direct and economy-wide economic losses of shellfish production by 2100. Estimates using the NPV method show that the direct potential losses due to reduced shellfish production range from 14% to 28% of fishery NPV. This equates to annual economic losses of between ö3 and ö6 billion of the UK’s GDP in 2013, for medium and high emission scenarios. Results using the PE model showed the total loss to the UK economy from shellfish production and consumption ranging from ö23–ö88 million. The results from both the direct valuation and predicted estimate for the economic losses on shellfish harvest indicate that there are regional variations due to different patterns of shellfish wild-capture and aquaculture, and the exploitation of species with differing sensitivities to ocean acidification. These results suggest that the potential economic losses vary depending on the chosen valuation method. This analysis is also partial as it did not include a wider group of species in early-life-stages or predator-prey effects. Nevertheless, findings show that the economic losses to the UK and its devolved administrations due to ocean acidification could be substantial. We conclude that addressing ocean acidification with the aim of preserving commercially valuable shellfish resources will require regional, national or international solutions using a combined approach to reduce atmospheric CO2 emissions and shift in focus to exploit species that are less vulnerable to ocean acidification.

Continue reading ‘The economic impacts of ocean acidification on shellfish fisheries and aquaculture in the United Kingdom’

An investigation into the physiological impacts of ocean acidification on recruits of the temperate coral, Oculina arbuscula

Ocean acidification is well-researched with respect to adult scleractinian corals, however information on whether adults and recruits of the same species respond similarly to this environmental stress is lacking. I investigated the responses to increased pCO2 of recruits of the temperate coral, Oculina arbuscula, whose adults are known to withstand high levels of pCO2 with no depression in calcification (up to 1000 ppm CO2). I addressed the hypothesis that O. arbuscula recruit health is not affected by increased pCO2 by exposing small colonies (5-12mm diameter) to 475, 711, and 1270 ppm CO2 for 75 days. Calcification rates were monitored throughout the experiment, while mortality, respiration rates, photosynthetic rates, zooxanthella densities, and soluble protein were determined at the end. As predicted, higher pCO2 did not impact survival, zooxanthella densities, or soluble protein. In contrast, both calcification rates and photosynthesis:respiration (P:R) ratios tended to be lower at higher pCO2. These results suggest that there is a size-dependent response to pCO2 within O. arbuscula, with recruits being unable to keep up with the increased energetic cost of calcification that occurs at higher pCO2. With the mean pCO2 increasing approximately 2.4% each year in the South Atlantic Bight (SAB), within the next 30 years O. arbuscula recruits are predicted to experience seasonal depressions in calcification rate driven by the overlying natural fluctuations in oceanic pCO2, and within 50 years recruits are anticipated to exhibit year-round depressions in calcification rate.

Continue reading ‘An investigation into the physiological impacts of ocean acidification on recruits of the temperate coral, Oculina arbuscula’

Trematode infection modulates cockles biochemical response to climate change

Highlights

• Higher infection success with water salinity decrease, warming and acidification
• Under lower water salinity, parasite infection reduced cockle antioxidant defence.
• Under higher water temperature, parasite infection increased cockle cellular damage.
• Under higher pCO2, parasite infection induced cockle metabolic depression.

Abstract

Resulting mainly from atmospheric carbon dioxide (CO2) build-up, seawater temperature rise is among the most important climate change related factors affecting costal marine ecosystems. Global warming will have implications on the water cycle, increasing the risk of heavy rainfalls and consequent freshwater input into the oceans but also increasing the frequency of extreme drought periods with consequent salinity increase. For Europe, by the end of the century, projections describe an increase of CO2 concentration up to 1120 ppm (corresponding to 0.5 pH unit decrease), an increase in the water temperature up to 4 °C and a higher frequency of heavy precipitation. These changes are likely to impact many biotic interactions, including host–parasite relationships which are particularly dependent on abiotic conditions. In the present study, we tested the hypothesis that the edible cockle, Cerastoderma edule, exposed to different salinity, temperature and pH levels as proxy for climate change, modify the infection success of the trematode parasite Himasthla elongata, with consequences to cockles biochemical performance. The results showed that the cercariae infection success increased with acidification but higher biochemical alterations were observed in infected cockles exposed to all abiotic experimental stressful conditions tested. The present study suggested that changes forecasted by many models may promote the proliferation of the parasites infective stages in many ecosystems leading to enhanced transmission, especially on temperate regions, that will influence the geographical distribution of some diseases and, probably, the survival capacity of infected bivalves.

Continue reading ‘Trematode infection modulates cockles biochemical response to climate change’

Shallow water carbonate sediments of the Galapagos archipelago: ecologically sensitive biofacies in a transitional oceanographic environment

Shallow water carbonate producing organisms are directly controlled by their local oceanography. As a result, long-term environmental signals—stemming from the breakdown of calcareous organisms—can be read from time-averaged carbonate sediments. To better understand these complex biophysical interactions, it is important to study carbonate development within oceanographic transition zones and environments affected by disturbances, such as the El Niño—Southern Oscillation (ENSO). This dissertation represents the first investigation into modern shallow water, soft sediment, carbonate environments of the Galápagos Archipelago, eastern tropical Pacific (ETP). This region is notable for straddling an oceanographic transition zone from tropical oligotrophic to temperate eutrophic—caused by high nutrient and low pH upwelling—and for being directly impacted by ENSO. A top-down approach is followed, which analyzes the biogenic structure of Galápagos sediments and their connection to local and regional oceanography and climate, and then explores how these findings relate to benthic foraminifera—sensitive environmental indicators contained within the sediments. Sediment point counting and statistical models revealed that while these carbonate environments span a biogenic and oceanographic transition comparable to similar settings in the ETP, the proximity of the Galápagos to the ENSO region directly influences its sedimentary structure and distribution. Point counting also revealed a near-absence of benthic foraminifera, which is unusual for ETP, and tropical shallow water carbonates in general. Statistically comparing foraminiferal species composition and diversity to dominant oceanographic parameters revealed the low abundances and distribution of these testate (shelled) single-celled protists to be negatively influenced by the combination of repeated Holocene ENSO events, and the effects of protracted exposure to high nutrient and low pH waters of the southern archipelago. Ultimately, the results of this study may serve as a template for investigating the interaction of carbonates and oceanography within similar atypical tropical assemblages in the fossil record.

Continue reading ‘Shallow water carbonate sediments of the Galapagos archipelago: ecologically sensitive biofacies in a transitional oceanographic environment’

The role of local environmental changes on maerl and its associated non-calcareous epiphytic flora in the Bay of Brest

Large stands of free living (calcareous) coralline algae — called maerl beds — play a major role as ecosystem engineers in coastal areas throughout the world. They are also subject to strong anthropogenic pressures at global and local scales, which threaten their survival. However, the macroalgal epiphytes growing on maerl may benefit from these pressures, developing to the detriment of maerl algae. Here, we sought to gain insight into how maerl beds and their epiphytic algae are disturbed by variations in the local environment, and how these variations affect their capacity to respond to global change. In 2015, we monitored three maerl beds located in the Bay of Brest (Brittany, France). Sites with contrasting conditions were selected, with one station lying in a zone close to the harbor (northern basin S1) and two stations (S2 and S3) located in areas away from the main urban effluents but subject to other sources of local change: higher currents at S3 (PREVIMER Ocean Forecast) and higher sedimentation rates at S2 (Erhold et al., 2015). We observed significant temporal variations of physico-chemical parameters, on an annual but also on a daily basis. Results showed that S2 differentiated itself from the other stations, this station experienced higher fluctuations of salinity, nutrient concentrations and carbonate system parameters and hosted the lowest (living) maerl biomass (4.38 ± 1.54 kg DW m−2). S3 observed the highest living maerl biomass (14.56 ± 1.61 kg DW m−2) and the lowest non-calcareous epiphytic macroalgal abundance (0.1–7.9 g DW m−2). S1 displayed the highest heterogeneity in terms of living maerl biomass (it varied from 0.8 to 8.6 kg DW m−2), and the highest Chl a content. However, we did not record differences in terms of physico-chemical parameters between S1 and S3. No positive relationship was observed between nutrient enrichment and macroalgal epiphyte abundance, but epiphyte abundance was higher at stations with lower maerl biomass (S1 and S2) (mean value ranged from 4.6 to 49.0 g DW m−2 at S1 and from 7.4 to 23.7 g DW m−2 at S2). Our results highlight the importance of local changes on the development, survival and capacity to adapt to global change of maerl beds.

Continue reading ‘The role of local environmental changes on maerl and its associated non-calcareous epiphytic flora in the Bay of Brest’

Metal fractionation in marine sediments acidified by enrichment of CO2: a risk assessment

Highlights

• Acidification related to CO2 leakages modifies the geochemistry of metals.
• Mobilization of metals from sediment into the water column is associated with their speciation.
• Sediments from Huelva Estuary have relevant concentrations of As, Cu, Pb and Zn.
• Risk assessment code analysis revealed that Zn presents the highest potential risk.

Abstract

Carbon-capture and storage is considered to be a potential mitigation option for climate change. However, accidental leaks of CO2 can occur, resulting in changes in ocean chemistry such as acidification and metal mobilization. Laboratory experiments were performed to provide data on the effects of CO2-related acidification on the chemical fractionation of metal(loid)s in marine-contaminated sediments using sequential extraction procedures. The results showed that sediments from Huelva estuary registered concentrations of arsenic, copper, lead, and zinc that surpass the probable biological effect level established by international protocols. Zinc had the greatest proportion in the most mobile fraction of the sediment. Metals in this fraction represent an environmental risk because they are weakly bound to sediment, and therefore more likely to migrate to the water column. Indeed, the concentration of this metal was lower in the most acidified scenarios when compared to control pH, indicating probable zinc mobilization from the sediment to the seawater.

Continue reading ‘Metal fractionation in marine sediments acidified by enrichment of CO2: a risk assessment’

Phytoplankton do not produce carbon‐rich organic matter in high CO2 oceans

The ocean is a substantial sink for atmospheric carbon dioxide (CO2) released as a result of human activities. Over the coming decades the dissolved inorganic C concentration in the surface ocean is predicted to increase, which is expected to have a direct influence on the efficiency of C utilization (consumption and production) by phytoplankton during photosynthesis. Here, we evaluated the generality of C‐rich organic matter production by examining the elemental C:N ratio of organic matter produced under conditions of varying pCO2. The data used in this analysis were obtained from a series of pelagic in situ pCO2 perturbation studies that were performed in the diverse ocean regions and involved natural phytoplankton assemblages. The C:N ratio of the resulting particulate and dissolved organic matter did not differ across the range of pCO2 conditions tested. In particular, the ratio for particulate organic C and N was found to be 6.58 ± 0.05, close to the theoretical value of 6.6.

Continue reading ‘Phytoplankton do not produce carbon‐rich organic matter in high CO2 oceans’


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Ocean acidification in the IPCC AR5 WG II

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