Posts Tagged 'mortality'

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’

Habitat effects of macrophytes and shell on carbonate chemistry and juvenile clam recruitment, survival, and growth

Highlights

• Field experiment testing two substrate treatments as OA adaptation strategies
• Clam growth increased in absence of macrophytes, regardless of shell hash treatment.
• Neither treatment improved clam recruitment or survival.
• pH in water column was higher during the day and outside eelgrass beds.
• Added shell hash improved carbonate chemistry in sediment pore-water.

Abstract

Adverse habitat conditions associated with reduced seawater pH often, but not always, negatively affect bivalves in early life history phases. Improving our understanding of how habitat-specific parameters affect clam recruitment, survival, and growth could assist natural resource managers and researchers in developing appropriate adaptation strategies for increasingly acidified nearshore ecosystems. Two proposed adaptation strategies, the presence of macrophytes and addition of shell hash, have the potential to raise local seawater pH and aragonite saturation state and, therefore, to improve conditions for shell-forming organisms. This field study examined the effects of these two substrate treatments on biological and geochemical response variables. Specifically, we measured (1) recruitment, survival, and growth of juvenile clams (Ruditapes philippinarum) and (2) local water chemistry at Fidalgo Bay and Skokomish Delta, Washington, USA, in response to experimental manipulations. Results showed no effect of macrophyte or shell hash treatment on recruitment or survival of R. philippinarum. Contrary to expectations, clam growth was significantly greater in the absence of macrophytes, regardless of the presence or absence of shell hash. Water column pH was higher outside the macrophyte bed than inside at Skokomish Delta and higher during the day than at night at Fidalgo Bay. Additionally, pore-water pH and aragonite saturation state were higher in the absence of macrophytes and the presence of shell. Based on these results, we propose that with increasingly corrosive conditions shell hash may help provide chemical refugia under future ocean conditions. Thus, we suggest adaptation strategies target the use of shell hash and avoidance of macrophytes to improve carbonate chemistry conditions and promote clam recruitment, survival, and growth.

Continue reading ‘Habitat effects of macrophytes and shell on carbonate chemistry and juvenile clam recruitment, survival, and growth’

Effect of CO2–induced ocean acidification on the early development and shell mineralization of the European abalone (Haliotis tuberculata)

Highlights
• Calcifying mollusks are among the most vulnerable invertebrates to (OA).
• Early life-history stages are particularly sensitive to pH changes.
• We investigated the effects of OA on larval development of the abalone H. tuberculata, a commercially important gastropod.
• Larval survival, development and shell calcification were affected by low pH conditions.
• OA may have potentially negative consequences for larval recruitment and persistence of abalone populations.

Abstract

Ocean acidification is a major global stressor that leads to substantial changes in seawater carbonate chemistry, with potentially significant consequences for calcifying organisms. Marine shelled mollusks are ecologically and economically important species providing essential ecosystem services and food sources for other species. Because they use calcium carbonate (CaCO3) to produce their shells, mollusks are among the most vulnerable invertebrates to ocean acidification, with early developmental stages being particularly sensitive to pH changes. This study investigated the effects of CO2-induced ocean acidification on larval development of the European abalone Haliotis tuberculata, a commercially important gastropod species. Abalone larvae were exposed to a range of reduced pHs (8.0, 7.7 and 7.6) over the course of their development cycle, from early-hatched trochophore to pre-metamorphic veliger. Biological responses were evaluated by measuring the survival rate, morphology and development, growth rate and shell calcification. Larval survival was significantly lower in acidified conditions than in control conditions. Similarly, larval size was consistently smaller under low pH conditions. Larval development was also affected, with evidence of a developmental delay and an increase in the proportion of malformed or unshelled larvae. In shelled larvae, the intensity of birefringence decreased under low pH conditions, suggesting a reduction in shell mineralization. Since these biological effects were observed for pH values expected by 2100, ocean acidification may have potentially negative consequences for larval recruitment and persistence of abalone populations in the near future.

Continue reading ‘Effect of CO2–induced ocean acidification on the early development and shell mineralization of the European abalone (Haliotis tuberculata)’

The effects of carbon dioxide on growth performance, welfare, and health of Atlantic salmon post-smolt (Salmo salar) in recirculating aquaculture systems

Highlights

• Atlantic salmon post-smolts were exposed to six CO2 concentrations (5–40 mg/L) for 12 weeks in 12 ppt salinity RAS
• Fish showed no mortality, cataracts, nephrocalcinosis or signs of external injuries.
• Skin dermis layer was significantly thinner in fish exposed to 40 mg/L of CO2.
• Body weight and growth were significantly lower at CO2 concentrations ≥12 mg/L.
• Effects of CO2 exposure during the RAS phase were carried over during an additional 6-week experimental period to mimic a seawater phase.

Abstract

High carbon dioxide (CO2) concentrations negatively impact fish, which makes data on its tolerance especially relevant for production systems that can accumulate CO2 such as recirculating aquaculture system (RAS). The current study evaluates the effect of CO2 on the growth performance, welfare, and health of Atlantic salmon post-smolts in RAS. This study consisted of two phases. The first was a CO2 exposure phase, where eighteen tanks were used with six treatments in triplicate: 5, 12, 19, 26, 33 and 40 mg/L of CO2 during 12 weeks in a 12 ppt salinity RAS (hereafter RAS phase). In the second phase, PIT-tagged fish were transferred to a 34 ppt salinity single flow-through tank at CO2 < 5 mg/L (hereafter seawater phase) for an additional 6-week experimental period mimicking a seawater phase. Overall, mortality of fish exposed to CO2 was low and not related to treatments. The mean final body weight was significantly higher in the 5 mg/L treatment compared to CO2 treatments ≥12 mg/L at the end of RAS phase and to CO2 treatments ≥33 mg/L at the end of seawater phase. Moreover, regressions showed that growth significantly decreased linearly with increasing CO2 in the water. Eye cataracts and visible external damage on skin, operculum, and fins were inexistent and similar among CO2 treatments. Kidneys showed no signs of mineral deposits in any of the structures of the tissue. However, skin analysis showed that fish exposed to high CO2 concentrations had a significantly thinner dermis layer (both at the end of RAS and seawater phase) and a significantly thinner epidermis layer and lower mucus cells count (at the end of seawater phase). In conclusion, Atlantic salmon post-smolts cultured in brackish water RAS showed a maximum growth performance at CO2 concentrations below 12 mg/L. Except skin, no major effects of health and welfare were observed, including cataracts and nephrocalcinosis. Further studies should evaluate the molecular and physiological responses to both short-term and long-term carbon dioxide exposure.

 

Continue reading ‘The effects of carbon dioxide on growth performance, welfare, and health of Atlantic salmon post-smolt (Salmo salar) in recirculating aquaculture systems’

You better repeat it: complex CO2 × temperature effects in Atlantic Silverside offspring revealed by serial experimentation

Concurrent ocean warming and acidification demand experimental approaches that assess biological sensitivities to combined effects of these potential stressors. Here, we summarize five CO2 × temperature experiments on wild Atlantic silverside, Menidia menidia, offspring that were reared under factorial combinations of CO2 (nominal: 400, 2200, 4000, and 6000 µatm) and temperature (17, 20, 24, and 28 °C) to quantify the temperature-dependence of CO2 effects in early life growth and survival. Across experiments and temperature treatments, we found few significant CO2 effects on response traits. Survival effects were limited to a single experiment, where elevated CO2 exposure reduced embryo survival at 17 and 24 °C. Hatch length displayed CO2 × temperature interactions due largely to reduced hatch size at 24 °C in one experiment but increased length at 28 °C in another. We found no overall influence of CO2 on larval growth or survival to 9, 10, 15 and 13–22 days post-hatch, at 28, 24, 20, and 17 °C, respectively. Importantly, exposure to cooler (17 °C) and warmer (28 °C) than optimal rearing temperatures (24 °C) in this species did not appear to increase CO2 sensitivity. Repeated experimentation documented substantial inter- and intra-experiment variability, highlighting the need for experimental replication to more robustly constrain inherently variable responses. Taken together, these results demonstrate that the early life stages of this ecologically important forage fish appear largely tolerate to even extreme levels of CO2 across a broad thermal regime.

Continue reading ‘You better repeat it: complex CO2 × temperature effects in Atlantic Silverside offspring revealed by serial experimentation’

Interactive effects of ocean acidification and ocean warming on Pacific herring (Clupea pallasi) early life stages

The synergy of ocean acidification and ocean warming may lead to negative effects in  marine organism responses that would be absent under single stressors. While adult fish are  effective acid-base regulators, early life stages may be more susceptible to environmental  stressors. Pacific herring are ecologically and economically important forage fish native to the  U.S. Pacific Northwest (PNW), and several herring populations in the PNW have experienced reductions in stock abundance. Studies to date have focused on Atlantic herring, and little is  known about the response of Pacific herring to ocean acidification and warming. Therefore, this  study focused on the combined effects of ocean acidification and warming on Pacific herring early life stages. We incubated Pacific herring embryos under a factorial design of two  temperature (10°C, 16°C) and two pCO2 (600 µatm, 1200 µatm) treatments from fertilization  until hatch (11 to 15 days depending on temperature). Elevated pCO2 was associated with a small increase in embryo mortality. However, elevated temperature was associated with greater  embryo mortality, greater embryo heart rates and yolk areas upon hatch, lower percent normal hatch, and decreased larval lengths. The interaction of elevated temperature and pCO2 was associated greater embryo respiration rates and yolk areas. This study indicates that temperature will likely be the primary global change stressor affecting Pacific herring embryology, and interactive effects with pCO2 may introduce additional challenges.
Continue reading ‘Interactive effects of ocean acidification and ocean warming on Pacific herring (Clupea pallasi) early life stages’

Potential ecotoxicological effects of elevated bicarbonate ion concentrations on marine organisms

Highlights

• Ecotoxicological effects of elevated DIC were evaluated using 10 marine organisms.
• Species-specific toxicity of elevated DIC were found with EC50 of 11–85 mM.
• Mortality for copepod T. japonicus was the most sensitive endpoint for DIC toxicity.
• Tentative criteria of DIC for protecting 80% of marine organisms is 11 mM.

Abstract

Recently, a novel method for carbon capture and storage has been proposed, which converts gaseous CO2 into aqueous bicarbonate ions (HCO3-), allowing it to be deposited into the ocean. This alkalinization method could be used to dispose large amounts of CO2 without acidifying seawater pH, but there is no information on the potential adverse effects of consequently elevated HCO3- concentrations on marine organisms. In this study, we evaluated the ecotoxicological effects of elevated concentrations of dissolved inorganic carbon (DIC) (max 193 mM) on 10 marine organisms. We found species-specific ecotoxicological effects of elevated DIC on marine organisms, with EC50-DIC (causing 50% inhibition) of 11-85 mM. The tentative criteria for protecting 80% of individuals of marine organisms are suggested to be pH 7.8 and 11 mM DIC, based on acidification data previously documented and alkalinization data newly obtained from this study. Overall, the results of this study are useful for providing baseline information on ecotoxicological effects of elevated DIC on marine organisms. More complementary studies are needed on the alkalinization method to determine DIC effects on seawater chemistry and marine organisms.

Continue reading ‘Potential ecotoxicological effects of elevated bicarbonate ion concentrations on marine organisms’


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Ocean acidification in the IPCC AR5 WG II

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