Posts Tagged 'review'

Stress across life stages: impacts, responses and consequences for marine organisms

Highlights

• The published data were analysed to assess carry-over effects on marine organisms.

• The capacity of larvae to recover from early starvation and hypoxia was tested.

• Food limitation is the main driver of negative carry-over effects on juvenile growth.

• Larvae can recover from the early stress without negative imprints as juveniles.

• Carry-over effects depend on the duration of stress relative to larval period.

Abstract

Population dynamics of marine organisms are strongly driven by their survival in early life stages. As life stages are tightly linked, environmental stress experienced by organisms in the early life stage can worsen their performance in the subsequent life stage (i.e. carry-over effect). However, stressful events can be ephemeral and hence organisms may be able to counter the harmful effects of transient stress. Here, we analysed the published data to examine the relative strength of carry-over effects on the juvenile growth of marine organisms, caused by different stressors (hypoxia, salinity, starvation, ocean acidification and stress-induced delayed metamorphosis) experienced in their larval stage. Based on 31 relevant published studies, we revealed that food limitation had the greatest negative carry-over effect on juvenile growth. In the laboratory, we tested the effects of short-term early starvation and hypoxia on the larval growth and development of a model organism, polychaete Hydroides elegans, and assessed whether the larvae can accommodate the early stress to maintain their performance as juveniles (settlement and juvenile growth). Results showed that early starvation for 3 days (∼50% of normal larval period) retarded larval growth and development, leading to subsequent reduced settlement rate and juvenile growth. When the starvation period decreased to 1 day, however, the larvae could recover from early starvation through compensatory growth and performed normal as juveniles (c.f. control). Early exposure to hypoxia did not affect larval growth (body length) and juvenile growth (tube length), but caused malformation of larvae and reduced settlement rate. We conclude that the adverse effects of transient stress can be carried across life stages, but depend on the duration of stressful events relative to larval period. As carry-over effects are primarily driven by energy acquisition, how food availability varies over time and space is fundamental to the population dynamics of marine organisms.

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Ocean acidification and deoxygenation in the North Pacific Ocean

FUTURE (Forecasting and Understanding Trends, Uncertainties and Responses of North Pacific Marine Ecosystems) is an integrative Scientific Program undertaken by the member countries and affiliates of the North Pacific Marine Science Organization (PICES) to understand how marine ecosystems in the North Pacific respond to climate change and human activities, to forecast ecosystem status based on contemporary understanding of how nature functions, and to communicate new insights to its members, governments, stakeholders, and the public.

FUTURE evolved from research conducted by its predecessor, the PICES/GLOBEC Climate Change and Carrying Capacity program, which had the goal of increasing understanding of climate influences on marine ecosystems. FUTURE continues a focus on understanding climate impacts on marine ecosystems and places additional emphasis on coastal anthropogenic influences, ecosystems forecasting, and engaging a broad user community with interests in North Pacific ecological and climate information.

This PICES Special Publication on ocean acidification and ocean deoxygenation is an important contribution to FUTURE’s principal objective of improving our knowledge and communication of the future of North Pacific ecosystems and the potential impacts of human activities on the North Pacific.

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Climate change, human impacts, and coastal ecosystems in the Anthropocene

Coastal zones, the world’s most densely populated regions, are increasingly threatened by climate change stressors — rising and warming seas, intensifying storms and droughts, and acidifying oceans. Although coastal zones have been affected by local human activities for centuries, how local human impacts and climate change stressors may interact to jeopardize coastal ecosystems remains poorly understood. Here we provide a review on interactions between climate change and local human impacts (e.g., interactions between sea level rise and anthropogenic land subsidence, which are forcing Indonesia to relocate its capital city) in the coastal realm. We highlight how these interactions can impair and, at times, decimate a variety of coastal ecosystems, and examine how understanding and incorporating these interactions can reshape theory on climate change impacts and ecological resilience. We further discuss implications of interactions between climate change and local human impacts for coastal conservation and elucidate the context when and where local conservation is more likely to buffer the impacts of climate change, attempting to help reconcile the growing debate about whether to shift much of the investment in local conservation to global CO2 emission reductions. Our review underscores that an enhanced understanding of interactions between climate change and local human impacts is of profound importance to improving predictions of climate change impacts, devising climate-smart conservation actions, and helping enhance adaption of coastal societies to climate change in the Anthropocene.

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Coral reef monitoring, reef assessment technologies, and ecosystem-based management

Coral reefs are exceptionally biodiverse and human dependence on their ecosystem services is high. Reefs experience significant direct and indirect anthropogenic pressures, and provide a sensitive indicator of coastal ocean health, climate change, and ocean acidification, with associated implications for society. Monitoring coral reef status and trends is essential to better inform science, management and policy, but the projected collapse of reef systems within a few decades makes the provision of accurate and actionable monitoring data urgent. The Global Coral Reef Monitoring Network has been the foundation for global reporting on coral reefs for two decades, and is entering into a new phase with improved operational and data standards incorporating the Essential Ocean Variables (EOVs) (www.goosocean.org/eov) and Framework for Ocean Observing developed by the Global Ocean Observing System. Three EOVs provide a robust description of reef health: hard coral cover and composition, macro-algal canopy cover, and fish diversity and abundance. A data quality model based on comprehensive metadata has been designed to facilitate maximum global coverage of coral reef data, and tangible steps to track capacity building. Improved monitoring of events such as mass bleaching and disease outbreaks, citizen science, and socio-economic monitoring have the potential to greatly improve the relevance of monitoring to managers and stakeholders, and to address the complex and multi- dimensional interactions between reefs and people. A new generation of autonomous vehicles (underwater, surface, and aerial) and satellites are set to revolutionize and vastly expand our understanding of coral reefs. Promising approaches include Structure from Motion image processing, and acoustic techniques. Across all systems, curation of data in linked and open online databases, with an open data culture to maximize benefits from data integration, and empowering users to take action, are priorities. Action in the next decade will be essential to mitigate the impacts on coral reefs from warming temperatures, through local management and informing national and international obligations, particularly in the context of the Sustainable Development Goals, climate action, and the role of coral reefs as a global indicator. Mobilizing data to help drive the needed behavior change is a top priority for coral reef observing systems.

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Carbon dioxide, pH, and alkalinity

The pH or negative logarithm of the hydrogen ion concentration is a master variable in water quality because the hydrogen ion influences many reactions. Because dissolved carbon dioxide is acidic, rainwater that is saturated with this gas is naturally acidic—usually about pH 5.6. Limestone, calcium silicate, and feldspars in soils and other geological formations dissolve through the action of carbon dioxide to increase the concentration of bicarbonate in water and raise the pH. The total concentration of titratable bases—usually bicarbonate and carbonate—expressed in milligrams per liter of calcium carbonate is the total alkalinity. Total alkalinity typically is less than 50 mg/L in waters of humid areas with highly leached soils, but it is greater where soils are more fertile, limestone formations are present, or the climate is arid. Alkalinity increases the availability of inorganic carbon for photosynthesis in waters of low to moderate pH. Water bodies with moderate to high alkalinity are well-buffered against wide daily swings in pH resulting from net removal of carbon dioxide by photosynthesis during daytime and return of carbon dioxide to the water by respiratory process at night when there is no photosynthesis. The optimum pH range for most aquatic organisms is 6.5–8.5, and the acid and alkaline death points are around pH 4 and pH 11, respectively. Fish and other aquatic animals avoid high carbon dioxide concentration, but 20 mg/L or more can be tolerated if there is plenty of dissolved oxygen. The optimum alkalinity for aquatic life is between 50 and 150 mg/L.

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Present and future adaptation of marine species assemblages: DNA-based insights into climate change from studies of physiology, genomics, and evolution

Marine species live in a dynamic physical and biological environment that demands frequent physiological adjustment and can result in strong natural selection or shifts in species ranges. We illustrate the patterns and processes of adaptation to environmental change with genetic-based examples that range from a focus on single proteins to whole genomes to whole communities. This work shows how single amino acid changes adapt proteins to function at different temperatures. It shows how acidification impacts expression of proteins in energy pathways in adults and exerts natural selection on many genes in larvae. Whole genome surveys along coastlines are now possible, and they reveal unexpected patterns of genetic differentiation even in highly dispersive species. Genetic surveys of over 70 species along the North American west coast show high levels of genetic diversity and genetic structure clustered at headlands and capes known to mark species range boundaries. Finally, new surveys of DNA variation in whole communities show promise for rapid monitoring that can augment and complement traditional dive surveys. Overall, dynamics in the physical environment have a strong effect on organism physiology, which results in diverse patterns of population growth and persistence, as well as of species range and evolutionary capacity. The high level of adaptive genetic variation shown here suggests an ability for marine populations to adapt in the face of climate change, but many questions remain about how fast, complete, and effective this evolution will be.

Continue reading ‘Present and future adaptation of marine species assemblages: DNA-based insights into climate change from studies of physiology, genomics, and evolution’

Connecting science to policymakers, managers, and citizens

Twenty years ago, the creation of a new scientific program, the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO), funded by the Packard Foundation, provided the opportunity to integrate—from the outset—research, monitoring, and outreach to the public, policymakers, and managers. PISCO’s outreach efforts were initially focused primarily on sharing scientific findings with lay audiences, but over time they evolved to a more interactive, multi-directional mode of engagement. Over the next two decades, PISCO science and scientists significantly influenced local, state, federal, and international decisions about many topics, but especially marine protected areas, hypoxia, ocean acidification, fishery management, and marine diseases. PISCO scientists’ long-term data and understanding of key ecosystem processes also enabled them to detect anomalies, investigate rapidly, and inform others about novel developments such as hypoxia, acidification, warming, and disease. Especially during a time of dynamic changes in ecosystems, long-term data like PISCO’s have proven invaluable. Moreover, PISCO’s dual focus on understanding fundamental processes and finding solutions (not just identifying problems) has resulted in rich opportunities to co-create knowledge with citizens and translate that knowledge into action by citizens, managers, and policymakers. PISCO has delivered on its goal to serve society through science.

Continue reading ‘Connecting science to policymakers, managers, and citizens’


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