Posts Tagged 'echinoderms'

Responses to climate change of the sea urchin (Pseudechinus sp.) and sea star (Odontaster validus) through hybridisation, local adaptations and transgenerational plasticity

Climate change, through ocean warming and ocean acidification, can affect the life cycles and population dynamics of marine species, which react by developing acclimation mechanisms. Sea urchins (Pseudechinus sp.) may hybridise with sympatric species or induce local adaptations geographically and sea stars (Odontaster validus) may develop transgenerational plasticity (TGP) in response to climate change. I studied their stress responses and if they developed potential acclimation capacity against climate change.

Continue reading ‘Responses to climate change of the sea urchin (Pseudechinus sp.) and sea star (Odontaster validus) through hybridisation, local adaptations and transgenerational plasticity’

Bioeconomic analysis of the impact of ocean acidification associated with low recruitment of Isostichopus badionotus and implications for adaptive fishery management in the north of the Yucatan Peninsula, Mexico

The impact that ocean acidification (OA) could generate in the fisheries of Isostichopus badionotus at the north of the Yucatan Peninsulta, Mexico, was analysed by reducing the value of a parameter of the Beverton-Holt recruitment function, in accordance with the acidification scenarios of the Intergovermental Panel Panel on Climate Change (IPCC). The behaviour of the stock and the resulting fishery were analysed in a bioeconomic model structured by age, taking into account different market prices and fishing efforts. The results were compared in decision matrices that used the MiniMax and MaxMin criteria to determine the management strategy that best reduced the impact of  acidification. The largest stock reduction occurred during the first years of exploitation (B10>B15/BO) and all the variables that were considered did stabilize with time, reaching bioeconomic equilibrium. The worst scenario for not considering acidification occurred with low market prices, while the increase in price decreased the exploitation rate. The recruitment reduction determined the maximum effort that should have been applied; under such conditions it is recommended to operate an effort of 137 boats, considering the best market price.

Continue reading ‘Bioeconomic analysis of the impact of ocean acidification associated with low recruitment of Isostichopus badionotus and implications for adaptive fishery management in the north of the Yucatan Peninsula, Mexico’

Trans‐life cycle acclimation to experimental ocean acidification affects gastric pH homeostasis and larval recruitment in the sea star Asterias rubens

Experimental simulation of near‐future ocean acidification (OA) has been demonstrated to affect growth and development of echinoderm larval stages through energy allocation towards ion and pH compensatory processes. To date, it remains largely unknown how major pH regulatory systems and their energetics are affected by trans‐generational exposure to near‐future acidification levels.

Here, we used the common sea star Asterias rubens in a reciprocal transplant experiment comprising different combinations of OA scenarios, to study trans‐generational plasticity using morphological and physiological endpoints.

Continue reading ‘Trans‐life cycle acclimation to experimental ocean acidification affects gastric pH homeostasis and larval recruitment in the sea star Asterias rubens’

Physiological and biochemical responses of a coralline alga and a sea urchin to climate change: Implications for herbivory

Highlights

• Algal metabolism and phenolic content were unaffected by CO2 and temperature treatments.
• CaCO3 content of algae decreased in high CO2 treatments.
• Total sugar content of algae was affected by both CO2 and temperature.
• Sea urchin respiration and feeding increased under high CO2, low temperature.
• Direct effects to sea urchin metabolism drove feeding more than algal palatability.

Abstract

Direct responses to rising temperatures and ocean acidification are increasingly well known for many single species, yet recent reviews have highlighted the need for climate change research to consider a broader range of species, how stressors may interact, and how stressors may affect species interactions. The latter point is important in the context of plant-herbivore interactions, as increasing evidence shows that increasing seawater temperature and/or acidification can alter algal traits that dictate their susceptibility to herbivores, and subsequently, community and ecosystem properties. To better understand how marine rocky shore environments will be affected by a changing ocean, in the present study we investigated the direct effects of short-term, co-occurring increased temperature and ocean acidification on a coralline alga (Jania rubens) and a sea urchin herbivore (Echinometra lucunter) and assessed the indirect effects of these factors on the algal-herbivore interaction. A 21-day mesocosm experiment was conducted with both algae and sea urchins exposed to ambient (24 °C, Low CO2), high-temperature (28 °C, Low CO2), acidified (24 °C, High CO2), or high-temperature plus acidified (28 °C, High CO2) conditions. Algal photosynthesis, respiration, and phenolic content were unaffected by increased temperature and CO2, but calcium carbonate content was reduced under high CO2 treatments in both temperatures, while total sugar content of the algae was reduced under acidified, lower temperature conditions. Metabolic rates of the sea urchin were elevated in the lower temperature, high CO2 treatment, and feeding assays showed that consumption rates also increased in this treatment. Despite some changes to algal chemical composition, it appears that at least under short-term exposure to climate change conditions, direct effects on herbivore metabolism dictated herbivory rates, while indirect effects caused by changes in algal palatability seemed to be of minor importance.

Continue reading ‘Physiological and biochemical responses of a coralline alga and a sea urchin to climate change: Implications for herbivory’

Physiological and behavioral plasticity of the sea cucumber Holothuria forskali (Echinodermata, Holothuroidea) to acidified seawater

Research into the effects of reduced pH caused by rising CO2 on echinoderms has been strongly biased toward those groups which rely heavily on calcification, such as sea urchins. There is very limited information available for groups that are less reliant on calcification, such as sea cucumbers. Moreover, plasticity in physiology and behavior in holothurians, which is considered to be critical to cope with ocean acidification, remains even less understood. Here, we examined the effects of a 22-week exposure to three pH levels (pH 7.97, 7.88, and 7.79) on the responses of adult Holothuria forskali. This is an abundant and ecologically important sea cucumber in shallow waters of the northeast Atlantic and Mediterranean. The holothurians did not exhibit serious acidosis after a 4-week gradually decreased pH exposure, possibly due to the slow acclimation period. After an additional 18 weeks of exposure, coelomic acid–base parameters did not differ significantly among the pH treatments, whereas they were higher than in week 4. Gonad development, defense behavior, and the structure and Ca2+ and Mg2+ concentrations of calcareous endoskeleton deposited in the body wall were all unaffected by decreased levels of seawater pH. No statistical differences were found after 22 weeks, and adult H. forskali showed strong physiological and behavioral plasticity to the effects of lowered seawater pH. While the interpretation of our results is restricted due to small sample sizes, this first long-term study of the effects of seawater acidification on sea cucumbers revealed resilience within the wide natural range of pCO2 found in NE Atlantic coastal waters.

Continue reading ‘Physiological and behavioral plasticity of the sea cucumber Holothuria forskali (Echinodermata, Holothuroidea) to acidified seawater’

Enhanced performance of juvenile crown of thorns starfish in a warm-high CO2 ocean exacerbates poor growth and survival of their coral prey

Declines in coral cover across the IndoPacific are associated with multiple stressors of global ocean change, and this is exacerbated by population outbreaks of the coral-eating crown of thorns starfish (COTS), Acanthaster spp. We investigated the growth and feeding responses of the corallivorous juvenile stage of COTS and their coral food, Acropora spp., to near-future ocean warming and acidification. Juvenile COTS and Acropora spp. were exposed to three temperatures (26, 28, 30 °C) and three pH levels (NIST scale: 8.0, 7.8, 7.6) in a flow-through cross-factorial experiment. Increased temperature and acidification had independent positive effects on growth and feeding of juvenile COTS. They grew faster and were larger under these conditions, but weighed less at low pH. Accelerated growth of juvenile COTS under ocean acidification conditions was decoupled from skeletogenesis with increased size largely due to development of soft tissue. Juveniles reared at 30 °C also had the greatest number of spines. To assess the recovery of Acropora spp. following sublethal COTS predation in warm and acidified conditions, corals that had been preyed on by the juveniles for 1 week were removed and held in experimental conditions to monitor their growth and survival. The stress from warming and predation had an interactive effect in reduction in coral growth. Mortality of corals was highest following predation and in the 30 °C treatments. There was no direct effect of acidification on growth or survival of Acropora spp. following predation. It appears that COTS juveniles may benefit from near-future warming and acidification. Thus, changing climate may increase the threat of this predatory starfish to coral reefs.

Continue reading ‘Enhanced performance of juvenile crown of thorns starfish in a warm-high CO2 ocean exacerbates poor growth and survival of their coral prey’

Development of the sea urchin Heliocidaris crassispina from Hong Kong is robust to ocean acidification and copper contamination

Highlights

• Ocean acidification will increase the fraction of the most toxic form of copper, increasing its bioavailability to marine organisms
• We tested the hypothesis that copper contaminated waters are more toxic to sea urchin larvae under future pH conditions in three laboratory experiments
• Larvae are robust to the pH and the copper levels we tested (little/no mortality)
• However, significant sub-lethal effects, could have indirect consequences on survival

Abstract

Metallic pollution is of particular concern in coastal cities. In the Asian megacity of Hong Kong, despite water qualities have improved over the past decade, some local zones are still particularly affected and could represent sinks for remobilization of labile toxic species such as copper. Ocean acidification is expected to increase the fraction of the most toxic form of copper (Cu2+) by 2.3-folds by 2100 (pH ≈7.7), increasing its bioavailability to marine organisms. Multiple stressors are likely to exert concomitant effects (additive, synergic or antagonist) on marine organisms.

Here, we tested the hypothesis that copper contaminated waters are more toxic to sea urchin larvae under future pH conditions. We exposed sea urchin embryos and larvae to two low-pH and two copper treatments (0.1 and 1.0 μM) in three separate experiments. Over the short time typically used for toxicity tests (up to 4-arm plutei, i.e. 3 days), larvae of the sea urchin Heliocidaris crassispina were robust and survived the copper levels present in Hong Kong waters today (≤0.19 μM) as well as the average pH projected for 2100. We, however, observed significant mortality with lowering pH in the longer, single-stressor experiment (Expt A: 8-arm plutei, i.e. 9 days). Abnormality and arm asymmetry were significantly increased by pH or/and by copper presence (depending on the experiment and copper level). Body size (d3; but not body growth rates in Expt A) was significantly reduced by both lowered pH and added copper. Larval respiration (Expt A) was doubled by a decrease at pHT from 8.0 to 7.3 on d6. In Expt B1.0 and B0.1, larval morphology (relative arm lengths and stomach volume) were affected by at least one of the two investigated factors.

Although the larvae appeared robust, these sub-lethal effects may have indirect consequences on feeding, swimming and ultimately survival. The complex relationship between pH and metal speciation/uptake is not well-characterized and further investigations are urgently needed to detangle the mechanisms involved and to identify possible caveats in routinely used toxicity tests.

Continue reading ‘Development of the sea urchin Heliocidaris crassispina from Hong Kong is robust to ocean acidification and copper contamination’


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OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book