Posts Tagged 'review'

The influence of ocean acidification on the economic vitality of shellfish hatcheries in the Pacific Northwest: A meta-analysis

Ocean acidification is the chemical process that results in the decrease of ocean pH levels. This decrease is caused by the diffusion of atmospheric carbon dioxide into Earth’s oceans. In other words, Earth’s oceans act as a carbon sink for atmospheric carbon. Prior to the industrial revolution in 1760, the ocean regulated the amount of carbon in earth’s atmosphere in a manner that did not threaten marine ecosystems. However, due to the increased combustion of fossil fuels due to rapid industrialization, urbanization, and population growth, oceans have begun to take up excessive amounts of carbon dioxide, resulting in an alteration of oceanic chemistry. The accumulation of hydrogen ions in ocean water due to the chemical reaction between carbonate carbon dioxide, and water have increased the acidity of the ocean. This has created a corrosive environment for shell-forming organisms that rely on carbonate for their exoskeletons. Many of these organisms, especially those in the Mollusca phylum, are commercially valuable. Ocean acidification has already begun its impact on the shellfish industry in the Pacific Northwest. However, if a business-as-usual scenario of carbon combustion prevails over use of alternative energy sources and mandatory terrestrial pollutant controls, the impact on shellfish aquaculture firms will only intensify and threaten the industry and its associated jobs and revenue. Local, state and federal authorities and agencies have begun to take steps to mitigate the effects of ocean acidification. Mitigation strategies are analyzed on their basis to effectively diminish the physiological and economic impact of ocean acidification on shellfish aquaculture operations. The question remains if these strategies will be able to successfully inhibit the ongoing process of ocean acidification, or simply just delay the impacts.

Continue reading ‘The influence of ocean acidification on the economic vitality of shellfish hatcheries in the Pacific Northwest: A meta-analysis’

Can seaweed farming play a role in climate change mitigation and adaptation?

Seaweed aquaculture, the fastest-growing component of global food production, offers a slate of opportunities to mitigate, and adapt to climate change. Seaweed farms release carbon that maybe buried in sediments or exported to the deep sea, therefore acting as a CO2 sink. The crop can also be used, in total or in part, for biofuel production, with a potential CO2 mitigation capacity, in terms of avoided emissions from fossil fuels, of about 1,500 tons CO2 km−2 year−1. Seaweed aquaculture can also help reduce the emissions from agriculture, by improving soil quality substituting synthetic fertilizer and when included in cattle fed, lowering methane emissions from cattle. Seaweed aquaculture contributes to climate change adaptation by damping wave energy and protecting shorelines, and by elevating pH and supplying oxygen to the waters, thereby locally reducing the effects of ocean acidification and de-oxygenation. The scope to expand seaweed aquaculture is, however, limited by the availability of suitable areas and competition for suitable areas with other uses, engineering systems capable of coping with rough conditions offshore, and increasing market demand for seaweed products, among other factors. Despite these limitations, seaweed farming practices can be optimized to maximize climate benefits, which may, if economically compensated, improve the income of seaweed farmers.

Continue reading ‘Can seaweed farming play a role in climate change mitigation and adaptation?’

Human dimensions of environmental change in small island developing states: some common themes

Climate change and its consequence of sea level rise are major issues for small island developing states (SIDS), as they worsen many other pressures on their people and their environment. Accordingly, articles in this special issue of Regional Environmental Change on SIDS address research gaps in the following thematic areas of the human dimensions of climate change. (1) Islander perceptions of climate change and the information sources on which these are based. (2) Migration to richer countries, which dominates popular media articles, so that scholars from a wide range of disciplines have given their perspectives on it. For many SIDS, however, relocation within that country is much more of an issue, but little studied as yet. (3) Community-based adaptation, a theme which only rarely appears in peer-reviewed journals. (4) National, regional and international policies and the effectiveness of their implementation. (5) Social and cultural issues arising from the above. This paper provides an overview of these and some related themes of importance to SIDS, including ocean acidification and land degradation. Researchers based in the SIDS and regional organisations have an important role in recognising these issues and in developing the local skills base needed to deal with them. The Paris Agreement of 2015 is a positive (but as yet inadequate) step towards the international action on climate change that SIDS need.

Continue reading ‘Human dimensions of environmental change in small island developing states: some common themes’

Impacts of climate change on fish and shellfish in the coastal and marine environments of Caribbean Small Island Developing States (SIDS)

The commercially important fish and shellfish of Caribbean SIDS have been considered in four groups based on environment and following the typical division of fishery groups used in this region.

There is a dearth of research and long-term datasets on the impacts of climate change on Caribbean marine environments and the important fishery resources. Most research to date has been outside of the Caribbean and has examined the impacts of one or two stressors in short-term ex situ experiments which are unlikely to accurately reflect the true complexity of long-term in situ impacts of climate change in the region. There is a need to consider the combined effects of climate change stressors (direct and indirect) on both individuals and ecosystems, together with the synergistic effects of other chronic anthropogenic stressors in the region.

We consider the reef-associated shallow shelf group to be the most vulnerable of the four fishery groups given: 1) the already apparent negative climate change impacts on their critical habitats; 2) the overexploited state of most reef-associated fishery stocks; 3) the already degraded state of their nearshore habitats as a result of other anthropogenic activities; and 4) their biphasic life history, requiring the ability to settle in specific benthic nursery habitat from a pelagic early life stage.

We consider the most resilient group, over the short-term, to be the oceanic pelagic species that generally show fewer negative responses to the climate change stressors given that they: 1) are highly mobile with generally good acid-base regulation; 2) have an entirely pelagic lifecycle; 3) have less vulnerable reproductive strategies (i.e. they have extended spawning seasons and over broad areas); and 4) are generally exposed to fewer or less severe anthropogenic stressors.

This summary is provided with the following important caveat: “Any attempt to report on what has already happened to fish and shellfish resources in the Caribbean, based on direct evidence, will be strongly biased by the fact that there is a lack of monitoring and directed research examining fish and shellfish species-level impacts of climate change in this region. As such, any conclusions drawn from direct evidence alone will likely misrepresent the true nature and extent of the climate change impacts on the coastal and marine fish and shellfish resources within the Caribbean to date.”

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Impacts of physical environments in the coastal and marine environments of Caribbean Small Island Developing States (SIDS)

Temperature – sea surface temperature has risen by more than 1 °C over the last 100 years. Future temperature rises will have impacts on hurricanes, rainfall, coral reefs and wider marine ecosystems.

Hurricanes – The IPCC (IPCC AR5 WG1) found strong evidence for an increase in the frequency and intensity of the strongest tropical hurricanes since the 1970s in the North Atlantic.

El Niño- Understanding the influence of the El Niño – Southern Oscillation (ENSO) phenomenon on Caribbean’s marine environment and timescales of variability is key to understanding how climate has been changing; projecting these relationships and ENSO itself into the future becomes vital to understand the fingerprint of global warming in the region.

Precipitation – there are a wide range of projections for future precipitation change in the area with some models finding increases in the coming century while most suggest a drier future for the region.

Ocean surface aragonite saturation state (Ωarg) has declined by around 3% in the Caribbean region relative to pre-industrial levels.

Climate variability – the Caribbean region needs a smaller increase in temperature for its conditions to become distinct (climate emergence) from the envelope of climate variability over the last hundred years, compared with the rest of the world.

Continue reading ‘Impacts of physical environments in the coastal and marine environments of Caribbean Small Island Developing States (SIDS)’

Impacts of ocean acidification in the coastal and marine environments of Caribbean Small Island Developing States (SIDS)

Oceans have absorbed one third of the carbon dioxide (CO2) released to the atmosphere from human activities causing the seawater pH to decrease by 0.1 units since the Industrial Revolution.

There is certainty that ocean acidification caused by anthropogenic activities is currently in progress and will increase in accord with rising atmospheric CO2 concentrations. There is medium confidence that these changes with significantly impact marine ecosystems.

Throughout the Caribbean small islands, ocean acidification effects could be exacerbated due to local processes within coastal zones. Ocean surface aragonite saturation state (Ωarg) has declined by around 3% in the Caribbean region relative to pre-industrial levels potentially already impacting tropical marine calcifying organisms. In addition to the effect on living organisms, ocean acidification is likely to diminish the structural integrity of coral reefs through reduced skeletal density, loss of calcium carbonate, and dissolution of high-Mg carbonate cements which help to bind the reef. This would make coastal areas of the Caribbean small islands increasingly more vulnerable to the action of waves and storm surge. This is likely to have knock-on effects to the tourism sector, fisheries and coastal infrastructure.

More studies about the present and projected impacts of ocean acidification on Caribbean small islands are necessary in order to evaluate alternative adaptive strategies accounting for the different island’s environmental, socioeconomic, and political settings.

Continue reading ‘Impacts of ocean acidification in the coastal and marine environments of Caribbean Small Island Developing States (SIDS)’

Impacts of climate change on coral in the coastal and marine environments of Caribbean Small Island Developing States (SIDS)

Coral reefs are integral to life in the Caribbean – providing protection from storms, sustaining national economies and livelihoods through tourism and fishing, and supporting culture, recreation and biodiversity conservation. Over a decade ago, their value was estimated at US$3.1 – 4.6 billion each year.

Climate change is already impacting coral reefs in the Caribbean, through coral bleaching, disease outbreaks, ocean acidification and physical damage from stronger hurricanes. Coral beaching is the most visible, wide-spread and iconic manifestation of climate change on reefs, with major events in the Caribbean in 1998, 2010 and 2015/16. The extent of bleaching and associated mortality varies by location and event, but has resulted in some mortality. Coral disease has already significantly altered the community composition of reefs in the Caribbean, and is projected to result in increasing frequency of outbreaks as seas warm. The lack of a centralized database to coordinate reef monitoring information, hampers efforts to measure these effects.

Ocean acidification is a direct chemical result of increased carbon dioxide, but it has a variety of different responses in different reef organisms. Corals are the brick foundations of the reef, with crustose coralline algae as their mortar. Both these critical functional groups are already being affected by the reduced pH of surface water, making it more difficult to calcify and grow.

Future impacts are expected to follow and accelerate on these trends.

By 2040–2043 projections are for the onset of annual severe bleaching, which would likely result in significant coral mortality. Disease outbreaks are predicted to become annual events several years earlier. Projections for future ocean acidification result in ocean carbonate saturation levels potentially dropping below those required to sustain coral reef accretion by 2050. Cutting emissions in CO2 (within RCP6.0) would buy many coral reefs a couple of decades more time before the worst impacts occur, but it delays rather than mitigates the threats posed to coral reefs by acidification and bleaching (Maynard et al, 2016).

National leaders of the Caribbean need to adamantly fight for CO2 emissions reductions, and ensure their reef management agencies take all precautionary measures needed to reduce local stress on their reefs to buy them additional time and resiliency potential for withstanding the stress of climate change.

Continue reading ‘Impacts of climate change on coral in the coastal and marine environments of Caribbean Small Island Developing States (SIDS)’


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Ocean acidification in the IPCC AR5 WG II

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