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AbstractClimate changes are altering the chemistry of the oceans, and knowing their effects on the biology of animals is urgent. Since the physiological responses of crustaceans may be different given the seasons of the year, this work evaluated the synergistic effect of ocean acidification and seasonality on the physiology of the sea-bob shrimp,Xiphopenaeus kroyeri. Experimental groups were exposed for 5 days to two levels of pH, representing present-day mean ambient conditions (pH 8.0) and distant-future conditions (pH 7.3) during the summer and winter. Metabolism, nitrogen excretion, energy type and storage were determined, respectively, by oxygen consumption, ammonia excretion, atomic ratio O/N and hepatosomatic index. The reduction of pH resulted in a decrease of about 30% in theX. kroyerimetabolism during the summer and winter. Nitrogen excretion (reduction of 40%) and hepatosomatic index (increase of 120%) showed to be altered in animals exposed to reduced pH only throughout summer. Regardless of pH and seasons of the year, animals use mainly proteins as energy substrate and they do not show mortality. The increase of the hepatosomatic index, indicator of the accumulation of energy reserves, associated with metabolism reduction, suggests the suppression of activities that demand energy expenditure. The consequences of the physiological alterations observed may include decreases in growth and reproduction rate and displacement of populations to more appropriate conditions. The results might be associated with a set of factors resulting from the exposure to reduced pH, the synergy between pH and temperature, but also with a pattern of different physiological responses that may occur according to seasonality.

AbstractClimate changes are altering the chemistry of the oceans, and knowing their effects on the biology of animals is urgent. Since the physiological responses of crustaceans may be different given the seasons of the year, this work evaluated the synergistic effect of ocean acidification and seasonality on the physiology of the sea-bob shrimp,Xiphopenaeus kroyeri. Experimental groups were exposed for 5 days to two levels of pH, representing present-day mean ambient conditions (pH 8.0) and distant-future conditions (pH 7.3) during the summer and winter. Metabolism, nitrogen excretion, energy type and storage were determined, respectively, by oxygen consumption, ammonia excretion, atomic ratio O/N and hepatosomatic index. The reduction of pH resulted in a decrease of about 30% in theX. kroyerimetabolism during the summer and winter. Nitrogen excretion (reduction of 40%) and hepatosomatic index (increase of 120%) showed to be altered in animals exposed to reduced pH only throughout summer. Regardless of pH and seasons of the year, animals use mainly proteins as energy substrate and they do not show mortality. The increase of the hepatosomatic index, indicator of the accumulation of energy reserves, associated with metabolism reduction, suggests the suppression of activities that demand energy expenditure. The consequences of the physiological alterations observed may include decreases in growth and reproduction rate and displacement of populations to more appropriate conditions. The results might be associated with a set of factors resulting from the exposure to reduced pH, the synergy between pH and temperature, but also with a pattern of different physiological responses that may occur according to seasonality.

Current shifts in ecosystem composition and function emphasize the need for an understanding of the links between environmental factors and organism fitness and tolerance. The examples discussed here illustrate how recent progress in the field of comparative physiology may provide a better mechanistic understanding of the ecological concepts of the fundamental and realized niches and thus provide insights into the impacts of anthropogenic disturbance. Here we argue that, as a link between physiological and ecological indicators of organismal performance, the mechanisms shaping aerobic scope and passive tolerance set the dimensions of an animal's niche, here defined as its capacity to survive, grow, behave, and interact with other species. We demonstrate how comparative studies of cod or killifish populations in a latitudinal cline have unraveled mitochondrial mechanisms involved in establishing a species' niche, performance, and energy budget. Riverine fish exemplify how the performance windows of various developmental stages follow the dynamic regimes of both seasonal temperatures and river hydrodynamics, as synergistic challenges. Finally, studies of species in extreme environments, such as the tilapia of Lake Magadi, illustrate how on evolutionary timescales functional and morphological shifts can occur, associated with new specializations. We conclude that research on the processes and time course of adaptations suitable to overcome current niche limits is urgently needed to assess the resilience of species and ecosystems to human impact, including the challenges of global climate change.

Current shifts in ecosystem composition and function emphasize the need for an understanding of the links between environmental factors and organism fitness and tolerance. The examples discussed here illustrate how recent progress in the field of comparative physiology may provide a better mechanistic understanding of the ecological concepts of the fundamental and realized niches and thus provide insights into the impacts of anthropogenic disturbance. Here we argue that, as a link between physiological and ecological indicators of organismal performance, the mechanisms shaping aerobic scope and passive tolerance set the dimensions of an animal's niche, here defined as its capacity to survive, grow, behave, and interact with other species. We demonstrate how comparative studies of cod or killifish populations in a latitudinal cline have unraveled mitochondrial mechanisms involved in establishing a species' niche, performance, and energy budget. Riverine fish exemplify how the performance windows of various developmental stages follow the dynamic regimes of both seasonal temperatures and river hydrodynamics, as synergistic challenges. Finally, studies of species in extreme environments, such as the tilapia of Lake Magadi, illustrate how on evolutionary timescales functional and morphological shifts can occur, associated with new specializations. We conclude that research on the processes and time course of adaptations suitable to overcome current niche limits is urgently needed to assess the resilience of species and ecosystems to human impact, including the challenges of global climate change.

Abstract Currently, in tropical regions such as the southern Gulf of Mexico (sGM), there are no legal guidelines for assessing the quality of the seafloor. We aim to determine whether the seafloor sustainability of the sGM is evenly distributed, based on pressures that human activities produce upon the marine coastal environment, represented by the water quality, sediment quality, and benthic fauna. We analysed physicochemical characteristics and benthic fauna at 183 sites, sampled during five annual surveys (rainy and dry seasons) in the sublittoral and bathyal zones. Socioeconomic indicators were obtained from official national censuses. We calculated a pressure index (PI) based on water quality, sediment quality, and socioeconomic indicators. PI values ranged from 1 to 2.67, with the highest values being observed at coastal sites. Our approach determined that the benthic quality in the study area was related to depth and oil industry influence and that the sGM's seafloor sustainability was unevenly distributed. For sustainability, we determined specific situations for each site or group of sites: (1) sensitive - sites with high benthic quality and low PI; (2) naturally variable - sites for which the poor benthic quality was not related to the PI; (3) degraded - sites with poor benthic quality and high PI; and (4) resilient - sites with good benthic quality and high PI. This differentiation in sustainability situations might be used as a reference for linking socioeconomic activities in the coasts with the ecological status of marine environments from shallow to deep.

Abstract Currently, in tropical regions such as the southern Gulf of Mexico (sGM), there are no legal guidelines for assessing the quality of the seafloor. We aim to determine whether the seafloor sustainability of the sGM is evenly distributed, based on pressures that human activities produce upon the marine coastal environment, represented by the water quality, sediment quality, and benthic fauna. We analysed physicochemical characteristics and benthic fauna at 183 sites, sampled during five annual surveys (rainy and dry seasons) in the sublittoral and bathyal zones. Socioeconomic indicators were obtained from official national censuses. We calculated a pressure index (PI) based on water quality, sediment quality, and socioeconomic indicators. PI values ranged from 1 to 2.67, with the highest values being observed at coastal sites. Our approach determined that the benthic quality in the study area was related to depth and oil industry influence and that the sGM's seafloor sustainability was unevenly distributed. For sustainability, we determined specific situations for each site or group of sites: (1) sensitive - sites with high benthic quality and low PI; (2) naturally variable - sites for which the poor benthic quality was not related to the PI; (3) degraded - sites with poor benthic quality and high PI; and (4) resilient - sites with good benthic quality and high PI. This differentiation in sustainability situations might be used as a reference for linking socioeconomic activities in the coasts with the ecological status of marine environments from shallow to deep.

The occurrence of the PHAILIN, HUDHUD cyclones in the Bay of Bengal region highlights the importance of continuous monitoring of this area from the coastal vulnerability perspective. The increase in the magnitude and frequency of coastal disasters is estimated to cause disastrous effects on the ever-increasing coastal population as well as the natural resources that are available in these regions. In this paper, the coastal vulnerability of a part of the Odisha coast, including the districts of Kendrapara and Jagatsinghpur, has been assessed on a relatively finer scale. These districts are reported to be the most vulnerable areas along the Odisha coast. A set of Physical–geological parameters and socio-economic factors are used to derive the vulnerability using AHP, and vulnerability maps are prepared to demarcate areas with different vulnerability. The Coastal Vulnerability Index (CVI) finally is grouped into the three vulnerability classes for the final coastal vulnerability map. Depending on this classification, approx. 35% of the coastline comes under high vulnerability, 39% under Medium and 26% under low vulnerability class. The coastline adjoining, Teisimouza, Barunei, Paradip, are the highly vulnerable zones whereas the shoreline between Jatardharmohan and Saharabedi comes under intermediate vulnerability zone. The results obtained can be used for prioritization of the most sensitive areas in this coastal belt for better strategic management.

The occurrence of the PHAILIN, HUDHUD cyclones in the Bay of Bengal region highlights the importance of continuous monitoring of this area from the coastal vulnerability perspective. The increase in the magnitude and frequency of coastal disasters is estimated to cause disastrous effects on the ever-increasing coastal population as well as the natural resources that are available in these regions. In this paper, the coastal vulnerability of a part of the Odisha coast, including the districts of Kendrapara and Jagatsinghpur, has been assessed on a relatively finer scale. These districts are reported to be the most vulnerable areas along the Odisha coast. A set of Physical–geological parameters and socio-economic factors are used to derive the vulnerability using AHP, and vulnerability maps are prepared to demarcate areas with different vulnerability. The Coastal Vulnerability Index (CVI) finally is grouped into the three vulnerability classes for the final coastal vulnerability map. Depending on this classification, approx. 35% of the coastline comes under high vulnerability, 39% under Medium and 26% under low vulnerability class. The coastline adjoining, Teisimouza, Barunei, Paradip, are the highly vulnerable zones whereas the shoreline between Jatardharmohan and Saharabedi comes under intermediate vulnerability zone. The results obtained can be used for prioritization of the most sensitive areas in this coastal belt for better strategic management.

A mesocosm experiment was conducted in Wuyuan Bay (Xiamen), China, to investigate the effects of elevated pCO2 on bloom formation by phytoplankton species previously studied in laboratory-based ocean acidification experiments, to determine if the indoor-grown species performed similarly in mesocosms under more realistic environmental conditions. We measured biomass, primary productivity and particulate organic carbon (POC) as well as particulate organic nitrogen (PON). Phaeodactylum tricornutum outcompeted Thalassiosira weissflogii and Emiliania huxleyi, comprising more than 99% of the final biomass. Mainly through a capacity to tolerate nutrient-limited situations, P. tricornutum showed a powerful sustained presence during the plateau phase of growth. Significant differences between high and low CO2 treatments were found in cell concentration, cumulative primary productivity and POC in the plateau phase but not during the exponential phase of growth. Compared to the low pCO2 (LC) treatment, POC increased by 45.8-101.9% in the high pCO2 (HC) treated cells during the bloom period. Furthermore, respiratory carbon losses of gross primary productivity were found to comprise 39-64% for the LC and 31-41% for the HC mesocosms (daytime C fixation) in phase II. Our results suggest that the duration and characteristics of a diatom bloom can be affected by elevated pCO2. Effects of elevated pCO2 observed in the laboratory cannot be reliably extrapolated to large scale mesocosms with multiple influencing factors, especially during intense algal blooms.