Posts Tagged 'North Atlantic'

Exploring coastal acidification and oyster restoration activities on the United States Atlantic coast

Executive Summary

The global ocean mediates the effect of climate change and anthropogenic carbon emissions by absorbing atmospheric carbon dioxide (Ellis et al., 2017). The ocean’s absorption of carbon dioxide results in a change in ocean chemistry and decline in seawater pH known as ocean acidification (Kapsenberg and Cyronak, 2018). Changes in ocean chemistry and pH may also be driven by primary production activity, upwelling, and river runoff into marine environments (Richards et al., 2014). Ocean acidification has the potential to adversely affect numerous marine organisms (Kapsenberg and Cyronak, 2018), however, it can be especially problematic for calcifying shellfish species (Swezey et al., 2020) like the Eastern Oyster and larval or juvenile stage organisms (Mangi et al., 2018). Temperature, salinity, dissolved oxygen levels, and acidification impact the health and longevity of oysters and oyster reefs. Oyster reefs offer numerous ecosystem services. These reefs provide habitat for benthic invertebrates, seabirds and fish that rely on reefs for feeding, nursery, and breeding grounds (Burrows et al., 2005). The Eastern Oyster (Crassostrea virginica) is a native oyster species of the U.S. Atlantic Coast. Although oysters reefs support coastal livelihoods and offer numerous ecosystem services, many reefs have been degraded by anthropogenic activities (Burrows et al., 2005). Pollution, over-harvest, and an increase in loading of suspended sediments are key threats to oyster reef health (Burrows et al., 2005). Oyster reef restoration projects focus on returning reefs to their natural state. Given the role of oysters as ecosystem engineers, and the many benefits that may be derived from healthy oyster reefs, restoration projects are a priority for communities throughout the U.S. Atlantic Coast.

Cooley et al. 2016 recommends several effective community actions that may be taken to help address ocean acidification today. This project focuses on two non-legislative actions discussed by Cooley et al. 2016. These are public education related to coastal acidification and resilience management through oyster reef restoration projects. The purpose of this project is to support coastal resource-reliant communities on the U.S. Atlantic Coast in preparing for the potential future impacts of ocean acidification on C. virginica. The project examines trends in the oyster reef restoration projects presently underway at the state and local level along the U.S. Atlantic Coast, and it considers how coastal acidification may affect the longevity of the region’s oyster reefs. Finally, the project considers the future research and management considerations needed to adequately protect oyster reefs under changing climatic conditions.

Continue reading ‘Exploring coastal acidification and oyster restoration activities on the United States Atlantic coast’

Seasonal photophysiological performance of adult western Baltic Fucus vesiculosus (Phaeophyceae) under ocean warming and acidification

Shallow coastal marine ecosystems are exposed to intensive warming events in the last decade, threatening keystone macroalgal species such as the bladder wrack (Fucus vesiculosus, Phaeophyceae) in the Baltic Sea. Herein, we experimentally tested in four consecutive benthic mesocosm experiments, if the single and combined impact of elevated seawater temperature (Δ + 5°C) and pCO2 (1100 ppm) under natural irradiance conditions seasonally affected the photophysiological performance (i.e., oxygen production, in vivo chlorophyll a fluorescence, energy dissipation pathways and chlorophyll concentration) of Baltic Sea Fucus. Photosynthesis was highest in spring/early summer when water temperature and solar irradiance increases naturally, and was lowest in winter (December to January/February). Temperature had a stronger effect than pCO2 on photosynthetic performance of Fucus in all seasons. In contrast to the expectation that warmer winter conditions might be beneficial, elevated temperature conditions and sub-optimal low winter light conditions decreased photophysiological performance of Fucus. In summer, western Baltic Sea Fucus already lives close to its upper thermal tolerance limit and future warming of the Baltic Sea during summer may probably become deleterious for this species. However, our results indicate that over most of the year a combination of future ocean warming and increased pCO2 will have slightly positive effects for Fucus photophysiological performance.

Continue reading ‘Seasonal photophysiological performance of adult western Baltic Fucus vesiculosus (Phaeophyceae) under ocean warming and acidification’

Impacts of multiple stressors on a benthic foraminiferal community: a long-term experiment assessing response to ocean acidification, hypoxia and warming

Ocean chemistry is changing as a result of human activities. Atmospheric carbon dioxide (CO2) concentrations are increasing, causing an increase in oceanic pCO2 that drives a decrease in oceanic pH, a process called ocean acidification (OA). Higher CO2 concentrations are also linked to rising global temperatures that can result in more stratified surface waters, reducing the exchange between surface and deep waters; this stronger stratification, along with nutrient pollution, contributes to an expansion of oxygen-depleted zones (so called hypoxia or deoxygenation). Determining the response of marine organisms to environmental changes is important for assessments of future ecosystem functioning. While many studies have assessed the impact of individual or paired stressors, fewer studies have assessed the combined impact of pCO2, O2, and temperature. A long-term experiment (∼10 months) with different treatments of these three stressors was conducted to determine their sole or combined impact on the abundance and survival of a benthic foraminiferal community collected from a continental-shelf site. Foraminifera are well suited to such study because of their small size, relatively rapid growth, varied mineralogies and physiologies. Inoculation materials were collected from a ∼77-m deep site south of Woods Hole, MA. Very fine sediments (<53 μm) were used as inoculum, to allow the entire community to respond. Thirty-eight morphologically identified taxa grew during the experiment. Multivariate statistical analysis indicates that hypoxia was the major driving factor distinguishing the yields, while warming was secondary. Species responses were not consistent, with different species being most abundant in different treatments. Some taxa grew in all of the triple-stressor samples. Results from the experiment suggest that foraminiferal species’ responses will vary considerably, with some being negatively impacted by predicted environmental changes, while other taxa will tolerate, and perhaps even benefit, from deoxygenation, warming and OA.

Continue reading ‘Impacts of multiple stressors on a benthic foraminiferal community: a long-term experiment assessing response to ocean acidification, hypoxia and warming’

Effects of ocean acidification on bleaching, survival, and calcification of Porites porites and P. astreoides in Cartagena, Colombia

Estimations of the ocean acidification-OA effects on marine environments indicate that coral reefs’ structure will collapse. This study aimed to determine the effects of OA, and its associated carbon chemistry in the sea water, on corals near the Colombian Caribbean city of Cartagena, taking as model organisms of the species Porites astreoides and P. porites. For each species, the effect of OA on bleaching, survival, and calcification was determined using artificial systems with pH of 7.879 ± 0.004 and 7.789 ± 0.007. The results showed that under the first pH, the bleaching of P. astreoides increased by 24.92% and its survival decreased by 80.56%, while at lowest pH, bleaching increased in 32.78% and survival decreased by 87.5%. In the case of P. porites, at first pH bleaching increased by 29.42% and survival decreased by 30.56% and at the lowest, bleaching increased in 37.32% and survival decreased by 13.39%. In both species, calcification was reduced in more than 90% at 7.879 ± 0.004 and their skeleton began to dissolve at 7.789 ± 0.007. This study represents the first effort to determine OA effects on Colombian Caribbean’s marine biota.

Continue reading ‘Effects of ocean acidification on bleaching, survival, and calcification of Porites porites and P. astreoides in Cartagena, Colombia’

Technical note: excess alkalinity in carbonate system reference materials

Certified reference materials (CRMs) for oceanic carbonate system measurements are critical for verifying the accuracy of laboratory protocols and the reliability of field sensors. CRMs are certified for total alkalinity and dissolved inorganic carbon, parameters that are (1) stable for a long period of time when a sample is properly stored and (2) not affected by changes in temperature and pressure. In experimentation initially designed to measure the total boron to salinity ratio of seawater, an interesting result has emerged regarding CRMs. A unique acidimetric titration method has indicated that three different batches of CRM contain excess alkalinity (i.e., alkalinity that is not attributable to inorganic bases included in the traditional definition of seawater total alkalinity) that is statistically greater than the excess alkalinity measured in open-ocean water from the Gulf of Mexico. Further, the amount of excess alkalinity appears to differ in certain CRM batches. Excess alkalinity in CRMs is likely caused by organic proton acceptors that are not completely oxidized by the ultraviolet sterilization procedure that CRMs undergo. The primary use of CRMs — to maintain the accuracy and consistency of carbonate system measurements — may be inhibited by excess alkalinity, which can cause differences in total alkalinity values determined by different titration methods. Excess alkalinity also invalidates the assumptions applied to CO2 system calculations, and so would produce incorrect values of CO2 system parameters calculated from certified total alkalinity and dissolved inorganic carbon values of CRMs. Finally, excess alkalinity analyses highlight the urgent need for the marine chemistry community to establish a universally agreed upon total boron to salinity ratio.

Continue reading ‘Technical note: excess alkalinity in carbonate system reference materials’

Cold-water corals in the Subpolar North Atlantic Ocean exposed to aragonite undersaturation if the 2 °C global warming target is not met

Highlights

  • Aragonite saturation state significantly decreased for 1991–2018.
  • Anthropogenic CO2 uptake is the main driver for the observed decrease.•
  • At cold-water corals (CWC) depths, the aragonite isolines shoaled at 6–34 m yr−1.
  • Projection of future change in aragonite saturation state based on observed change.
  • CWC reefs exposed to undersaturation at atmospheric CO2 levels causing 2 °C warming.

Abstract

The net uptake of carbon dioxide (CO2) from the atmosphere is changing the ocean’s chemical state. Such changes, commonly known as ocean acidification, include a reduction in pH and the carbonate ion concentration ([CO32−]), which in turn lowers oceanic saturation states (Ω) for calcium carbonate (CaCO3) minerals. The Ω values for aragonite (Ωaragonite; one of the main CaCO3 minerals formed by marine calcifying organisms) influence the calcification rate and geographic distribution of cold-water corals (CWCs), important for biodiversity. Here, high-quality measurements, collected on thirteen cruises along the same track during 1991–2018, are used to determine the long-term changes in Ωaragonite in the Irminger and Iceland Basins of the North Atlantic Ocean, providing the first trends of Ωaragonite in the deep waters of these basins. The entire water column of both basins showed significant negative Ωaragonite trends between −0.0014 ± 0.0002 and − 0.0052 ± 0.0007 per year. The decrease in Ωaragonite in the intermediate waters, where nearly half of the CWC reefs of the study region are located, caused the Ωaragonite isolines to rapidly migrate upwards at a rate between 6 and 34 m per year. The main driver of the decline in Ωaragonite in the Irminger and Iceland Basins was the increase in anthropogenic CO2. But this was partially offset by increases in salinity (in Subpolar Mode Water), enhanced ventilation (in upper Labrador Sea Water) and increases in alkalinity (in classical Labrador Sea Water, cLSW; and overflow waters). We also found that water mass aging reinforced the Ωaragonite decrease in cLSW. Based on these Ωaragonite trends over the last three decades, we project that the entire water column of the Irminger and Iceland Basins will likely be undersaturated for aragonite when in equilibrium with an atmospheric mole fraction of CO2 (xCO2) of ~880 ppmv, corresponding to climate model projections for the end of the century based on the highest CO2 emission scenarios. However, intermediate waters will likely be aragonite undersaturated when in equilibrium with an atmospheric xCO2 exceeding ~630 ppmv, an xCO2 level slightly above that corresponding to 2 °C global warming, thus exposing CWCs inhabiting the intermediate waters to undersaturation for aragonite.

Continue reading ‘Cold-water corals in the Subpolar North Atlantic Ocean exposed to aragonite undersaturation if the 2 °C global warming target is not met’

Combined effect of microplastics and global warming factors on early growth and development of the sea urchin (Paracentrotus lividus)

Highlights

  • This work focusses on the effect of a multi-stressor environment in sea urchin.
  • Embryo-larval bioassays were used to determine growth and morphometric parameters.
  • A lower water pH (7.6) reduced larval growth and caused deformities.
  • Microplastics aggravate the effect of water acidification in sea urchin larvae.
  • High temperatures caused an additional stress and reduced larvae stomach volume.

Abstract

The aim of this work was to estimate the potential risk of the combined effect of global change factors (acidification, temperature increase) and microplastic (MP) pollution on the growth and development of the sea urchin P. lividus. Embryo-larval bioassays were conducted to determine growth and morphology after 48 h of incubation with MP (1000 and 3000 particles/mL); with filtered sea water at pH = 7.6; and with their combinations. A second experiment was conducted to study the effect of pH and MP in combination with a temperature increase of 4 °C compared to control (20 °C). We found that the inhibition of growth in embryos reared at pH = 7.6 was around 75%. Larvae incubated at 3000 MP particles/mL showed a 20% decrease in growth compared to controls. The exposure to MP also induced an increase in the postoral arm separation or rounded vertices. The combined exposure to a pH 7.6 and MP caused a significant decrease of larval growth compared to control, to MP and to pH 7.6 treatments. Morphological alterations were observed in these treatments, including the development of only two arms. Increasing the temperature resulted in an increased growth in control, in pH 7.6 and pH 7.6 + MP3000 treatments, but the relative stomach volume decreased. However, when growth parameters were expressed per Degree-Days the lower growth provoked by the thermal stress was evidenced in all treatments. In this work we demonstrated that MP could aggravate the effect of a decreased pH and that an increase in water temperature generated an additional stress on P. lividus larvae, manifested in a lower growth and an altered development. Therefore, the combined stress caused by ocean warming, ocean acidification, and microplastic pollution, could threaten sea urchin populations leading to a potential impact on coastal ecosystems.

Continue reading ‘Combined effect of microplastics and global warming factors on early growth and development of the sea urchin (Paracentrotus lividus)’

Risk assessment for key socio-economic and ecological species in a sub-arctic marine ecosystem under combined ocean acidification and warming

The Arctic may be particularly vulnerable to the consequences of both ocean acidification (OA) and global warming, given the faster pace of warming and acidification. Here, we use the Atlantis ecosystem model to assess how the trophic network of marine fishes and invertebrates in the Icelandic waters is responding to the combined pressures of OA and warming. We develop an approach which allows us to focus on species of economic (catch-value), social (number of participants in fisheries), or ecological (keystone species) importance. We parameterize the model with literature-determined ranges of sensitivity to OA and warming for different species and functional groups in the Icelandic waters. We found divergent species responses to warming and acidification levels; (mainly) planktonic groups and forage fish benefited while (mainly) benthic groups and predatory fish decreased under warming and acidification scenarios. Assuming conservative harvest rates for the largest catch-value species, Atlantic cod, we see that the population is projected to remain stable under even the harshest acidification and warming scenario. Further, for the scenarios where the model projects reductions in biomass of Atlantic cod, other species in the ecosystem increase, likely due to a reduction in competition and predation. These results highlight the interdependencies of multiple global change drivers and their cascading effects on trophic organization, and the supply of an important species from a socio-economic perspective in the Icelandic fisheries.

Continue reading ‘Risk assessment for key socio-economic and ecological species in a sub-arctic marine ecosystem under combined ocean acidification and warming’

Seasonal mixing and biological controls of the carbonate system in a river-dominated continental shelf subject to eutrophication and hypoxia in the Northern Gulf of Mexico

Large rivers export a large amount of dissolved inorganic carbon (DIC) and nutrients to continental shelves; and subsequent river-to-sea mixing, eutrophication, and seasonal hypoxia (dissolved oxygen < 2 mg⋅L–1) can further modify DIC and nutrient distributions and fluxes. However, quantitative studies of seasonal carbonate variations on shelves are still insufficient. We collected total alkalinity (TA), DIC, and NO3 data from nine cruises conducted between 2006 and 2010 on the northern Gulf of Mexico continental shelf, an area strongly influenced by the Mississippi and Atchafalaya Rivers. We applied a three-end-member model (based on salinity and potential alkalinity) to our data to remove the contribution of physical mixing to DIC and nitrate distribution patterns and to derive the net in situ removal of DIC and nitrate (ΔDIC and ΔNO3, respectively). Systematic analyses demonstrated that the seasonal net DIC removal in the near-surface water was strong during summer and weak in winter. The peak in net DIC production in the near-bottom, subsurface waters of the inner and middle sections of the shelf occurred between July and September; it was coupled, but with a time lag, to the peak in the net DIC removal that occurred in the near-surface waters in June. A similar 2-month delay (i.e., January vs. November) could also be observed between their minima. A detailed examination of the relationship between ΔDIC and ΔNO3 demonstrates that net biological activity was the dominant factor of DIC removal and addition. Other effects, such as air–sea CO2 gas exchange, wetland exports, CaCO3 precipitation, and a regional variation of the Redfield ratio, were relatively minor. We suggest that the delayed coupling between eutrophic surface and hypoxic bottom waters reported here may also be seen in the carbon and nutrient cycles of other nutrient-rich, river-dominated ocean margins worldwide.

Continue reading ‘Seasonal mixing and biological controls of the carbonate system in a river-dominated continental shelf subject to eutrophication and hypoxia in the Northern Gulf of Mexico’

Aiding ocean development planning with SDG relationships in small island developing states

Promoting the Sustainable Development Goals (SDGs) must contend with the often siloed nature of governance institutions, making the identification of cooperative institutional networks that promote SDG targets a priority. We develop and apply a method that combines SDG interaction analysis, which helps determine prerequisites for SDG attainment, with the transition management framework, which helps align policy goals with institutional designs. Using Aruba as a case study, we show that prioritizing increased economic benefits from sustainable marine development, including those of tourism, provides the greatest amount of direct co-benefits to other SDGs. When considering indirect co-benefits, reducing marine pollution emerged as a key supporting target to achieve SDGs. The results also show that, as in many other small island states, sustainable ocean development in Aruba depends on international partnerships to address global issues—including climate change mitigation—over which it has little control. Using SDG relationships as a guide for institutional cooperation, we find that the institutions with the most potential to coordinate action for sustainable ocean development are those that address economic, social and international policy, rather than institutions specifically focused on environmental policy. Our results provide key methodologies and insights for sustainable marine development that require coordinated actions across institutions.

Continue reading ‘Aiding ocean development planning with SDG relationships in small island developing states’

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Ocean acidification in the IPCC AR5 WG II

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