Posts Tagged 'biological response'



CO2-driven ocean acidification repressed the growth of adult sea urchin Strongylocentrotus intermedius by impairing intestine function

Highlights

• Ocean acidification (OA) depressed the growth of adult Strongylocentrotus intermedius.

• The food consumption of adult S. intermedius decreased with declining pH.

• Intestinal morphology and activities of metabolic enzymes were changed.

• Relative expression levels of SiTNF14 and SiTGF-β were altered under OA stress.

Abstract

Strongylocentrotus intermedius cultured in the northern Yellow Sea in China was utilized to evaluate the effects of chronic CO2-driven ocean acidification (OA) on adult sea urchins. Based on the projection of the Intergovernmental Panel on Climate Change (IPCC), present natural seawater conditions (pHNBS = 8.10 ± 0.03) and three laboratory-controlled OA conditions (OA1, ΔpHNBS = − 0.3 units; OA2, ΔpHNBS = − 0.4 units; OA3, ΔpHNBS = − 0.5 units) were employed. After 60-day incubation, our results showed that (1) OA significantly repressed the growth of adult S. intermedius; (2) food consumption tended to be decreased with pH decline; (3) intestinal morphology was changed, and activities of intestinal cellulase and lipase were decreased under acidified conditions; (4) expression levels of two immune-related genes (SiTNF14 and SiTGF-β) were altered; (5) rate-limiting enzyme activities of the glycolytic pathway and tricarboxylic acid cycle (TAC) were changed in all OA treatments compared to those of controls.

Continue reading ‘CO2-driven ocean acidification repressed the growth of adult sea urchin Strongylocentrotus intermedius by impairing intestine function’

Full annual monitoring of Subantarctic Emiliania huxleyi populations reveals highly calcified morphotypes in high-CO2 winter conditions

Ocean acidification is expected to have detrimental consequences for the most abundant calcifying phytoplankton species Emiliania huxleyi. However, this assumption is mainly based on laboratory manipulations that are unable to reproduce the complexity of natural ecosystems. Here, E. huxleyi coccolith assemblages collected over a year by an autonomous water sampler and sediment traps in the Subantarctic Zone were analysed. The combination of taxonomic and morphometric analyses together with in situ measurements of surface-water properties allowed us to monitor, with unprecedented detail, the seasonal cycle of E. huxleyi at two Subantarctic stations. E. huxleyi subantarctic assemblages were composed of a mixture of, at least, four different morphotypes. Heavier morphotypes exhibited their maximum relative abundances during winter, coinciding with peak annual TCO2 and nutrient concentrations, while lighter morphotypes dominated during summer, coinciding with lowest TCO2 and nutrients levels. The similar seasonality observed in both time-series suggests that it may be a circumpolar feature of the Subantarctic zone. Our results challenge the view that ocean acidification will necessarily lead to a replacement of heavily-calcified coccolithophores by lightly-calcified ones in subpolar ecosystems, and emphasize the need to consider the cumulative effect of multiple stressors on the probable succession of morphotypes.

Continue reading ‘Full annual monitoring of Subantarctic Emiliania huxleyi populations reveals highly calcified morphotypes in high-CO2 winter conditions’

Ocean acidification impacts on hatching success and reproductive tissue damage in anemonefish

Oceans have continuously absorbed anthropogenic carbon dioxide from the atmosphere. The early life stages are likely vulnerable to low pH conditions. The present study aimed to assess the anemonefish (Amphiprionsebae), egg hatch rate and gonadal tissue condition in different pH levels in 6 weeks. Seawater
pH was manually manipulated by bubbling known concentrations of CO2 to achieve three pH treatments 8.1, 7.7 and 7.3. Egg hatch rate decreased with declining pH (ambient pH – 93 %, pH 7.7 – 92 %, pH 7.3 – 88 %) and a slight time delay was observed between the ambient and lower pH treatments. The condition of testicular and ovarian tissue was not affected by low pH levels. Overall, present experiment found that the slight negative effects on egg hatching success in low pH condition. The experimental results suggested that early life stages expected to vulnerable to near future ocean acidification.

Continue reading ‘Ocean acidification impacts on hatching success and reproductive tissue damage in anemonefish’

The combined effect of zinc and pH on growth rate and chlorophyll content of brown seaweed, Padina boryana

Brown seaweed, Padina boryana is found along the coast of Terengganu, Malaysia and may serve as a potential heavy metal biomonitor in the coastal zones. To better understand the impact of heavy metal pollution on P. boryana at varying seawater pH levels, the combined effect of zinc (Zn) and pH on its growth rate and chlorophyll content was investigated in laboratory exposures. After exposure for 21 days in a mixed treatment of 6 pH variations (4 to 9) and three Zn concentrations (30, 150, 300 ppb), maximum growth rate was observed in controlled treatments at pH 8 with no added Zn, whereas treatments at pH 4 and 9 showed negative growth rates after 18 days. The growth rate and chlorophyll content of P. boryana decreased significantly with an increase in Zn concentration. At pH 6, 7 and 8, P. boryana showed significant decreases (p < 0.05) in growth rates and chlorophyll content in all concentrations of Zn compared with control plants (no Zn). At pH of 6.0 and below, controls were also affected with significantly reduced growth rates and chlorophyll contents while Zn treated seaweed showed significant effects compared to these controls. The effect of pH and Zn on all measured factors was obvious on Day 6 onwards, whereas the interaction effect between them was significant on chlorophyll content throughout the experiment. From Day 9 onwards, the growth rate and chlorophyll content showed significant correlation among each other.

Continue reading ‘The combined effect of zinc and pH on growth rate and chlorophyll content of brown seaweed, Padina boryana’

The effects of temperature and pCO2 on the size, thermal tolerance and metabolic rate of the red sea urchin (Mesocentrotus franciscanus) during early development

The red sea urchin Mesocentrotus franciscanus supports a highly valuable wild fishery along the West Coast of North America, but despite its importance in the ecology of kelp forests and as a harvested species, little is known about how M. franciscanus responds to abiotic stressors associated with ocean warming and acidification during its early development. Here, embryos of M. franciscanus were raised under combinations of two temperatures (13 °C and 17 °C) and two pCO2 levels (475 μatm and 1050 μatm) that represent current and future coastal environments. Elevated pCO2 levels led to a decrease in body size of gastrula stage embryos while temperature had no effect. At the prism stage, both temperature and pCO2 affected body size. The warmer temperature increased the body size of prism stage embryos, offsetting the stunting effect of elevated pCO2 on growth. Thermal tolerance, which was estimated by exposing prism stage embryos to a range of temperatures and estimating the survivorship, was found to be slightly higher in those raised under warmer temperatures. The developmental temperature and pCO2 conditions under which embryos were raised did not have an effect on the metabolic rate as measured by oxygen consumption rate at the prism stage. This study provides important insights into a species of high ecological and economic value. Overall, early development under elevated pCO2 conditions may adversely impact M. franciscanus while moderate warming may improve growth and thermal tolerance. Understanding how fishery species respond to abiotic stressors will facilitate our predictive capacity of how climate change will impact future populations, which links to issues such as sustainability and food security.

Continue reading ‘The effects of temperature and pCO2 on the size, thermal tolerance and metabolic rate of the red sea urchin (Mesocentrotus franciscanus) during early development’

Marine clade sensitivities to climate change conform across timescales

Rapid climate change is postulated to cause marine extinctions, especially among climate-sensitive clades, traits and regions1,2,3,4,5,6. This premise is based on two hypotheses: (1) known individual physiological sensitivities scale up to macroecological selectivity patterns4,7,8 and (2) ancient hyperthermal events are appropriate models to anticipate ecological winners and losers of anthropogenic climate change9. Yet these hypotheses have largely escaped quantitative appraisal. Here we show that experimental responses of modern marine ectotherms to single and combined climate-related stressors (such as seawater warming, hypoxia and acidification) align with Phanerozoic fossil extinction regimes across clades and functional traits. Of climate-related stressors, the synergistic interaction between warming and hypoxia10, encumbering aerobic metabolism, has the greatest potency as a proximate driver of extinction. All else being equal8, this synergy particularly imperils modern warm-water organisms. Modern–fossil agreement is strongest at intermediate–high extinction intensities and hyperthermal events but may fail at extreme extinction events, perhaps due to rising prominences of, and interactions among, additional biotic and abiotic stressors. According to results from marine ectotherms, clade-based sensitivity of individuals to climate-related stressors scales up from subannual experiments and decadal range-shift response magnitudes11, to extinction selectivity patterns at ancient climate-related stressor events and the Phanerozoic durations of genera.

Continue reading ‘Marine clade sensitivities to climate change conform across timescales’

Food availability modulates the combined effects of ocean acidification and warming on fish growth

When organisms are unable to feed ad libitum they may be more susceptible to negative effects of environmental stressors such as ocean acidification and warming (OAW). We reared sea bass (Dicentrarchus labrax) at 15 or 20 °C and at ambient or high PCO2 (650 versus 1750 µatm PCO2; pH = 8.1 or 7.6) at ad libitum feeding and observed no discernible effect of PCO2 on the size-at-age of juveniles after 277 (20 °C) and 367 (15 °C) days. Feeding trials were then conducted including a restricted ration (25% ad libitum). At 15 °C, growth rate increased with ration but was unaffected by PCO2. At 20 °C, acidification and warming acted antagonistically and low feeding level enhanced PCO2 effects. Differences in growth were not merely a consequence of lower food intake but also linked to changes in digestive efficiency. The specific activity of digestive enzymes (amylase, trypsin, phosphatase alkaline and aminopeptidase N) at 20 °C was lower at the higher PCO2 level. Our study highlights the importance of incorporating restricted feeding into experimental designs examining OAW and suggests that ad libitum feeding used in the majority of the studies to date may not have been suitable to detect impacts of ecological significance.

Continue reading ‘Food availability modulates the combined effects of ocean acidification and warming on fish growth’


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Ocean acidification in the IPCC AR5 WG II

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