Posts Tagged 'crustaceans'

Homarus gammarus (Crustacea: Decapoda) larvae under an ocean acidification scenario: responses across different levels of biological organization

The present study evaluated the effects of exposure to different target pCO2 levels: control (C: 370μatm, pH = 8.15) and ocean acidification (OA: 710μatm, pH = 7.85) on development and biochemical responses related with oxidative stress and energy metabolism during the crustacean Homarus gammarus (L.) larval development, integrating different levels of biological organization. After hatching in the laboratory, larvae from the same female brood were exposed to the described conditions from hatching until reaching Stage III (last larval stage – 11 days). H. gammarus larvae demonstrated some susceptibility when addressing the predicted pCO2 levels for 2100. Further analysis at the biochemical and physiological level highlighted the occurrence of oxidative stress in the OA scenario (Superoxide Dismutase reduction and higher DNA damage) that was followed by developmental effects, increased inter-moult period from SII to SIII and reduced growth. The extended exposure to these conditions may affect organisms’ key life-cycle functions such as physiological resistance, growth, sexual maturation, or reproduction with implications in their future fitness and population dynamics.

Continue reading ‘Homarus gammarus (Crustacea: Decapoda) larvae under an ocean acidification scenario: responses across different levels of biological organization’

Variable metabolic responses of Skagerrak invertebrates to low O2 and high CO2 scenarios

Coastal hypoxia is a problem that is predicted to increase rapidly in the future. At the same time we are facing rising atmospheric CO2 concentrations, which are increasing the pCO2 and acidity of coastal waters. These two drivers are well studied in isolation however; the coupling of low O2 and pH is likely to provide a more significant respiratory challenge for slow moving and sessile invertebrates than is currently predicted. The Gullmar Fjord in Sweden is home to a range of habitats such as sand and mud flats, seagrass beds, exposed and protected shorelines, and rocky bottoms. Moreover, it has a history of both natural and anthropogenically enhanced hypoxia as well as North Sea upwelling, where salty water reaches the surface towards the end of summer and early autumn. A total of 11 species (Crustacean, Chordate, Echinoderm and Mollusc) of these ecosystems were exposed to four different treatments (high/low oxygen and low/high CO2; varying pCO2 of 450 and 1300 ppm and O2 concentrations of 2–3.5 and 9–10 mg L−1) and respiration measured after 3 and 6 days, respectively. This allows us to evaluate respiration responses of species of contrasting habitats and life-history strategies to single and multiple stressors. Results show that the responses of the respiration were highly species specific as we observed both synergetic as well as antagonistic responses, and neither phylum nor habitat explained trends in respiratory responses. Management plans should avoid the generalized assumption that combined stressors will results in multiplicative effects and focus attention on alleviating hypoxia in the region.
Continue reading ‘Variable metabolic responses of Skagerrak invertebrates to low O2 and high CO2 scenarios’

Ocean acidification impacts the embryonic development and hatching success of the Florida stone crab, Menippe mercenaria

Highlights

  • Lower seawater pH slowed the rate of stone crab embryonic development by 24%.
  • Lower seawater pH also significantly reduced stone crab hatching success.
  • Reduced pH had no effect on larval morphology.
  • Variability in the hatching suggests the potential for acclimatization within the species.


Abstract

The deterioration of coastal habitats due to anthropogenic activities is being caused by nutrient rich runoff which will likely result in more frequent and severe extremes in seawater pH. The embryonic and larval stages of many coastal species may not have the physiological ability to tolerate these extreme shifts in pH forecasted for future oceans. The stone crab, Menippe mercenaria, was used to determine the impact of low seawater pH on embryonic development and hatching success. Ovigerous females were maintained in environments characteristic of both present-day and reduced seawater pH. Lower pH significantly reduced the rate of embryonic development (i.e., time to hatching) by ~ 24%, but had no effect on the size of developing embryos (i.e., embryonic volume). Larvae that successfully hatched were not morphologically different between treatments, although hatching success was reduced by 28% in lower pH seawater. Hatching success was also more variable in the reduced pH treatment indicating that some broods may be more tolerant to changes in seawater acidity. Variable hatching success under acidified conditions suggests that stone crab embryos may have the capacity to acclimatize to future seawater pH conditions.

 

Continue reading ‘Ocean acidification impacts the embryonic development and hatching success of the Florida stone crab, Menippe mercenaria’

Ocean acidification alters zooplankton communities and increases top-down pressure of a cubozoan predator

The composition of local ecological communities is determined by the members of the regional community that are able to survive the abiotic and biotic conditions of a local ecosystem. Anthropogenic activities since the industrial revolution have increased atmospheric CO2 concentrations, which have in turn decreased ocean pH and altered carbonate ion concentrations: so called ocean acidification (OA). Single-species experiments have shown how OA can dramatically affect zooplankton development, physiology and skeletal mineralization status, potentially reducing their defensive function and altering their predatory and antipredatory behaviors. This means that increased OA may indirectly alter the biotic conditions by modifying trophic interactions. We investigated how OA affects the impact of a cubozoan predator on their zooplankton prey, predominantly Copepoda, Pleocyemata, Dendrobranchiata, and Amphipoda. Experimental conditions were set at either current (pCO2 370 μatm) or end-of-the-century OA (pCO2 1,100 μatm) scenarios, crossed in an orthogonal experimental design with the presence/absence of the cubozoan predator Carybdea rastoni. The combined effects of exposure to OA and predation by C. rastoni caused greater shifts in community structure, and greater reductions in the abundance of key taxa than would be predicted from combining the effect of each stressor in isolation. Specifically, we show that in the combined presence of OA and a cubozoan predator, populations of the most abundant member of the zooplankton community (calanoid copepods) were reduced 27% more than it would be predicted based on the effects of these stressors in isolation, suggesting that OA increases the susceptibility of plankton to predation. Our results indicate that the ecological consequences of OA may be greater than predicted from single-species experiments, and highlight the need to understand future marine global change from a community perspective.

Continue reading ‘Ocean acidification alters zooplankton communities and increases top-down pressure of a cubozoan predator’

Reduced growth and survival in the larval blue crab Callinectes sapidus under predicted ocean acidification

The decreasing average pH of the world’s oceans, called ocean acidification, can be detrimental to marine organisms. Decreased pH causes dissolution of calcium carbonate shells, as well as changes to metabolism, behavior, growth, survival, and early development of many species; however, the impacts of lower pH on crustaceans have not been widely researched. This study investigated the effects of lower pH on the growth and survival of larval blue crabs Callinectes sapidus through laboratory experiments. Blue crab larvae live at the surface of the open ocean where the pH is decreasing with ocean acidification. A pH of 7.8 was used to mimic the average surface ocean pH predicted to be attained by 2,100 by the Intergovernmental Panel on Climate Change and was compared with a control pH of 8.2, the current average surface ocean pH. Larvae raised at the lower pH were 10% smaller and there was a 23% reduction in survival. Larval populations within an aquarium with a lower pH were more likely to exhibit sudden die-offs than larvae raised at the control pH.

Continue reading ‘Reduced growth and survival in the larval blue crab Callinectes sapidus under predicted ocean acidification’

Survival and osmoregulation of the purple marsh crab (Sesarma reticulatum) at varying salinity and pH

Overfishing of top predators along the western Atlantic coastline has led to a trophic cascade in salt marshes, with increases in herbivorous purple marsh crab (Sesarma reticulatum; Say, 1817) abundances in North American estuaries leading to overgrazing of cordgrass (Spartina alterniflora, Loisel.) and shoreline erosion. To evaluate potential physiological limits on the range of S. reticulatum within an estuary, we evaluated survival and physiological tolerance of S. reticulatum from the Ashepoo-Combhee-Edisto (ACE) River Basin in South Carolina, USA, to combinations of salinity (5 and 30 ‰) and pH (pH 6.6, 7.6, and 8.6) challenges, representative of estuarine extremes. Survival, haemolymph ion concentrations, and gill Na+K+ATPase (NKA) and V-type H+-ATPase (VHA) activity were measured after a 48-hr exposure to each experimental condition. Survival was nearly 100 % and osmoregulatory control was maintained across estuarine salinity and pH ranges. Sesarma reticulatum appeared to be robust to all potential combinations of salinity and pH stressors examined in this study, and therefore are likely unrestricted in their fundamental niche based on these stressors throughout an estuary.

Continue reading ‘Survival and osmoregulation of the purple marsh crab (Sesarma reticulatum) at varying salinity and pH’

Effects of elevated CO2 and temperature on an intertidal harpacticoid copepod community

Warming and ocean acidification have been shown to have significant impacts on marine organisms. However, none studies have addressed the impact of these two stressors on harpacticoid copepod community structure. A mesocosm experiment was conducted to assess the potential interactive impact of different levels of elevated CO2 and temperature on an intertidal harpacticoid copepod community. Artificial substrate units (ASUs) colonized by meiofauna from the extreme low intertidal zone were exposed to eight experimental treatments (four pH levels: 8.0, 7.7, 7.3 and 6.7, crossed with two temperature levels: 12 and 16 °C). After 60 days exposure communities were significantly affected by both stressors. The dominant harpacticoid species were mainly affected at treatments held at pH 6.7, but with divergent biological response patterns. At pH 6.7 Tisbe sp and Ectinosoma sp2 exhibited important density reductions, while considerable density increases were observed for Amphiascus longarticulatus and Amphiascoides golikovi. This study has demonstrated that elevated levels of CO2 and ocean warming may have substantial effects on the structure of harpacticoid communities. Importantly, the increase in malformations observed at pH 6.7 indicated that we need to consider sub-lethal effects that could have consequences for populations after long periods of exposure.

Continue reading ‘Effects of elevated CO2 and temperature on an intertidal harpacticoid copepod community’


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Ocean acidification in the IPCC AR5 WG II

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