Posts Tagged 'review'

An enhanced ocean acidification observing network: from people to technology to data synthesis and information exchange

A successful integrated ocean acidification (OA) observing network must include (1) scientists and technicians from a range of disciplines from physics to chemistry to biology to technology development; (2) government, private, and intergovernmental support; (3) regional cohorts working together on regionally specific issues; (4) publicly accessible data from the open ocean to coastal to estuarine systems; (5) close integration with other networks focusing on related measurements or issues including the social and economic consequences of OA; and (6) observation-based informational products useful for decision making such as management of fisheries and aquaculture. The Global Ocean Acidification Observing Network (GOA-ON), a key player in this vision, seeks to expand and enhance geographic extent and availability of coastal and open ocean observing data to ultimately inform adaptive measures and policy action, especially in support of the United Nations 2030 Agenda for Sustainable Development. GOA-ON works to empower and support regional collaborative networks such as the Latin American Ocean Acidification Network, supports new scientists entering the field with training, mentorship, and equipment, refines approaches for tracking biological impacts, and stimulates development of lower-cost methodology and technologies allowing for wider participation of scientists. GOA-ON seeks to collaborate with and complement work done by other observing networks such as those focused on carbon flux into the ocean, tracking of carbon and oxygen in the ocean, observing biological diversity, and determining short- and long-term variability in these and other ocean parameters through space and time.

Continue reading ‘An enhanced ocean acidification observing network: from people to technology to data synthesis and information exchange’

Effects of ocean acidification on marine photosynthetic organisms under the concurrent influences of warming, UV radiation, and deoxygenation

The oceans take up over 1 million tons of anthropogenic CO2 per hour, increasing dissolved pCO2 and decreasing seawater pH in a process called ocean acidification (OA). At the same time greenhouse warming of the surface ocean results in enhanced stratification and shoaling of upper mixed layers, exposing photosynthetic organisms dwelling there to increased visible and UV radiation as well as to a decreased nutrient supply. In addition, ocean warming and anthropogenic eutrophication reduce the concentration of dissolved O2 in seawater, contributing to the spread of hypoxic zones. All of these global changes interact to affect marine primary producers. Such interactions have been documented, but to a much smaller extent compared to the responses to each single driver. The combined effects could be synergistic, neutral, or antagonistic depending on species or the physiological processes involved as well as experimental setups. For most calcifying algae, the combined impacts of acidification, solar UV, and/or elevated temperature clearly reduce their calcification; for diatoms, elevated CO2 and light levels interact to enhance their growth at low levels of sunlight but inhibit it at high levels. For most photosynthetic nitrogen fixers (diazotrophs), acidification associated with elevated CO2 may enhance their N2 fixation activity, but interactions with other environmental variables such as trace metal availability may neutralize or even reverse these effects. Macroalgae, on the other hand, either as juveniles or adults, appear to benefit from elevated CO2 with enhanced growth rates and tolerance to lowered pH. There has been little documentation of deoxygenation effects on primary producers, although theoretically elevated CO2 and decreased O2 concentrations could selectively enhance carboxylation over oxygenation catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase and thereby benefit autotrophs. Overall, most ocean-based global change biology studies have used single and/or double stressors in laboratory tests. This overview examines the combined effects of OA with other features such as warming, solar UV radiation, and deoxygenation, focusing on primary producers.

Continue reading ‘Effects of ocean acidification on marine photosynthetic organisms under the concurrent influences of warming, UV radiation, and deoxygenation’

Spectrophotometric determination of pH and carbonate ion concentrations in seawater: choices, constraints and consequences

Highlights
• Spectrophotometric pH and carbonate ion measurements in seawater.

• Different application platforms, such as shipboard, underway, in situ, etc.

• Quality improvement with indicator purification, sample pre-treatment, etc.

• Carbonate ion to be considered as the fifth parameter describing carbonate system.

Abstract
Accurate and precise marine CO2 system measurements are important for marine carbon cycle research and investigations of ocean acidification. Seawater pH is important because it can be used to characterize a wide range of chemical and biogeochemical processes. Saturation states of calcium carbonate minerals, which are directly proportional to carbonate ion concentration ([CO32-]), influence biogenic calcification and rates of carbonate dissolution. Spectrophotometric pH and carbonate ion measurements can both benefit greatly from the high sensitivity, stability, consistency and processing speed made possible through automation. Spectrophotometric methods are well-suited for shipboard, underway and in situ deployments under harsh conditions. Spectrophotometric pH measurements typically have a reproducibility of 0.0004-0.001 for shipboard and laboratory measurements and 0.0014-0.004 for in situ measurements. Shipboard spectrophotometric measurements of [CO32-] are becoming common on research expeditions. This review highlights the development of methods and instrumentation for spectrophotometric pH and [CO32-] measurements, and discusses the pros and cons of current technology. A comprehensive summary of the analytical merits of different flow analysis instruments is given. Aspects of measurement protocols that bear on the quality of pH and [CO32-] measurements, such as indicator purification, sample pretreatment, etc., are also described. Based on three decades of experience with seawater analysis, this review includes method recommendations and perspectives directly applicable or potentially applicable to pH and [CO32-] analysis of seawater.

Continue reading ‘Spectrophotometric determination of pH and carbonate ion concentrations in seawater: choices, constraints and consequences’

People and the changing nature of coral reefs

Highlights

• Large numbers of people in tropical regions are highly dependent on the goods and services produced by coral reef ecosystems.

• Coral reef ecosystems are under severe threat from both local and global threats, which are degrading the ecosystem services that they provide to humanity.

• Past studies have assumed that the loss of ecosystem services will lead to a proportionate impact on people.

• We argue that this is unlikely to be the case in the short-term due to the high level of adaptability illustrated by communities associated with coral reefs. Eventually, however, stress will reach levels that exhaust the capacity of people and communities to adapt.

• Data sets and analysis are sparse, however, we call for a greater focus on understanding the flexibility and adaptability of people associated with coral reefs, especially in a time of rapid global change.

Abstract

Coral reefs are biodiverse and productive ecosystems but are threatened by local and global stresses. The resulting loss of coral reefs is threatening coastal food and livelihoods. Climate projections suggest that coral reefs will continue to undergo major changes even if the goals of the Paris Agreement (Dec 2015) are successfully implemented. Ecological changes include modified food webs, shifts in community structure, reduced habitat complexity, decreased fecundity and recruitment, changes to fisheries productivity/opportunity, and a shift in the carbonate budget of some ecosystems toward dissolution and erosion of calcium carbonate stocks. Broad estimates of the long-term (present value) of services provided by the ocean’s ecological assets exist and are useful in highlighting the value of reefs yet must be contextualised by how people respond under ecosystem change. The dynamic nature of the relationship between people, economies, and the environment complicates estimation of human consequences and economic outcomes of changing environmental and ecological capital. Challenges have increased given lack of baseline data and our inability to predict (with any precision) how people respond to changing coral reef conditions, especially given the variability, flexibility, and creativity shown by human communities and economies under change. Here, we explore how the changes to the three-dimensional structure of coral reefs affect benefits for people, specifically coastal protection, fisheries habitat, and tourism. Based on a review of available data and literature, we make a series of key recommendations that are required to better understanding of how global change will affect people dependent on coral reefs. These include: (1) baseline studies and frameworks for understanding human responses to climate change within complex social and ecological setting such as coral reefs, (2) better tools for exploring environmental benefits, markets, and financial systems faced by change, and (3) the integration of these insights into more effective policy making.

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Behavioral adaptations of sandy beach macrofauna in face of climate change impacts: a conceptual framework

Highlights
• An overview of macrofauna behavioral adaptations to sandy beach features is provided.

• The effects of main climate change drivers on sandy beaches are summarized.

• Specific hypotheses are formulated for how behavioral adaptations are predicted to respond to climate change impacts.

• Biodiversity loss will be the outcome of the negative pressures driven by climate change.

Abstract
Sandy beaches are severely under-represented in the literature on climate-change ecology, yet different lines of evidence suggest that the macrofauna inhabiting these narrow and dynamic environments located at the land-sea interface is being reorganized under the influence of this large scale and long-lasting stressor. This is reflected in macrofaunal sensitivity to increasing sea surface temperature, sea-level rise, extreme events and erosion of the narrow physical habitat. However, evidence of behavioral responses by sandy beach macrofauna that are consistent with expectations under climate change is scarce and fragmentary. In this paper, specific hypotheses are formulated for how behavioral adaptations in sandy beach macrofauna are predicted to respond to climate change impacts. Firstly, a conceptual framework and an overview of macrofauna behavioral adaptation features are provided. Secondly, the effects of main climate change drivers on sandy beaches are summarized. Thirdly, a conceptual framework is developed giving behavioral adaptations of sandy beach macrofauna under climate change pressure. The degree to which observations on behavioral adaptations of beach animals conform to expectations under specific climate change drivers (sea level rise, sea surface temperature, winds and storminess, rainfall, acidification and eutrophication) is explored. Taking into account the empirical evidence and the theoretical framework detailed in the paper, emergent hypotheses/predictions are proposed. Climate change drivers are expected to impact habitat features and consequently the behavioral expression of macrofauna as active responses to habitat changes. Behavioral adaptations are expected to be impaired, more variable or disrupted, thus decreasing fitness, causing local population extirpations and potentially triggering a range of cascading effects of ecological change in the beach ecosystem. Biodiversity loss will be the outcome of the negative pressures driven by climate change. The specificity of sandy beaches as narrow ecotones between sea and land may be lost under climate change pressure, adversely affecting fine-tuned macrofaunal adaptations and therefore ecosystem functioning. Strictly adapted endemic sandy beach fauna will be especially subjected to local extirpations, while species with a large reaction norm (i.e. phenotypic and behavioral plasticity) may face changes by dispersal and exploitation of new niches. Under climate change impacts, biodiversity loss is predicted, which would hamper beach ecosystem resilience. The limits to which sandy beach macrofauna responds and can behaviorally adapt to environmental change are worthy of exploration, in view of the increasing influence of the long-lasting climate driven stressors threatening these ecosystems at risk.

Continue reading ‘Behavioral adaptations of sandy beach macrofauna in face of climate change impacts: a conceptual framework’

The oceans are changing: impact of ocean warming and acidification on biofouling communities

Climate change (CC) is driving modification in the chemical and physical properties of estuaries and oceans with profound consequences for species and ecosystems. Numerous studies investigate its effect from species to ecosystem levels, however little is known on impacts on biofilm communities and bioactive molecules, like cues, glues, and enzymes. CC is induced by anthropogenic activity increasing greenhouse emissions leading to rises in air and water temperatures, ocean acidification, sea level rise and changes in ocean gyres and rainfall patterns. These environmental changes are resulting in alterations in marine communities and spreading of species (pathogens, invasives). This review provides insights and synthesis of knowledge about the effect of elevated temperature and ocean acidification on microfouling communities and bioactive molecules. The existing studies suggest that CC will impact production of bioactive compounds, growth and composition of biofouling communities. Undoubtedly, with CC fouling management will became an even greater challenge.

Continue reading ‘The oceans are changing: impact of ocean warming and acidification on biofouling communities’

Harmful algal blooms: a climate change co-stressor in marine and freshwater ecosystems

Highlights

• Harmful algal blooms (HABs) are intensifying in parallel with climate change.
• Few studies have followed interactive effects between climate change stressors and HAB species.
• Future studies with HAB species should consider incorporating multiple climate change stressors.

Abstract

Marine and freshwater ecosystems are warming, acidifying, and deoxygenating as a consequence of climate change. In parallel, the impacts of harmful algal blooms (HABs) on these ecosystems are intensifying. Many eutrophic habitats that host recurring HABs already experience thermal extremes, low dissolved oxygen, and low pH, making these locations potential sentinel sites for conditions that will become more common in larger-scale systems as climate change accelerates. While studies of the effects of HABs or individual climate change stressors on aquatic organisms have been relatively common, studies assessing their combined impacts have been rare. Those doing so have reported strong species- and strain-specific interactions between HAB species and climate change co-stressors yielding outcomes for aquatic organisms that could not have been predicted based on investigations of these factors individually. This review provides an ecological and physiological framework for considering HABs as a climate change co-stressor and considers the consequences of their combined occurrence for coastal ecosystems. This review also highlights critical gaps in our understanding of HABs as a climate change co-stressor that must be addressed in order to develop management plans that adequately protect fisheries, aquaculture, aquatic ecosystems, and human health. Ultimately, incorporating HAB species into experiments and monitoring programs where the effects of multiple climate change stressors are considered will provide a more ecologically relevant perspective of the structure and function of marine ecosystems in future, climate-altered systems.

Continue reading ‘Harmful algal blooms: a climate change co-stressor in marine and freshwater ecosystems’


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OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book