Posts Tagged 'reproduction'

Exposure time modulates the effects of climate change-related stressors on fertile sporophytes and early-life stage performance of a habitat-forming kelp species

Highlight

  • Ocean warming (OW) reduced the sorus photosynthetic performance.
  • OW reduced meiospore germination rate.
  • OW and ocean acidification reduced meiospore release (MR).
  • MR is more sensitive to temperature changes than to pCO2 changes.
  • Longer exposure to OW increased the negative effects on germination rate.

Abstract

Understanding the impact of increases in pCO2 (OA) and extreme changes in temperature on marine organisms is critical to predicting how they will cope with climate change. We evaluated the effects of OA as well as warming and cooling trend temperature on early reproductive traits of Lessonia trabeculata, a foundation kelp species. Sori discs were maintained for an exposure time (ET) of 3 (T3) and 7 (T7) days to one of two contrasting pCO2 levels (450 and 1100 μatm). In addition, at each pCO2 level, they were subjected to three temperature treatments: 15 °C (control), 10 °C (cool) and 19 °C (warm). Subsequently, we compared sorus photosynthetic performance (Fv/Fm), the number of meiospores released (MR) and their germination rate (GR) after 48 h of settlement, with values obtained from sori discs not exposed (DNE) to the treatments. The Fv/Fm measured for DNE was lower than at T3 and T7 at 10 and 15 °C but not at 19 °C. Regardless of temperature, we found no significant differences between MR measured at T0 and T3 were found. MR at T7 was significantly lower at 19 °C than at 10 and 15 °C. We found only aA significant reduction in MR in response to elevated pCO2 was only found at T3. The GR of meiospores released by DNE and then maintained for 48 h to 19 °C decreased significantly by ∼33 % when compared with those maintained for the same time at 10 and 15 °C. A similar, but more drastic reduction (∼54 %) in the GR was found in meiospores released by sori discs exposed for T3 and maintained for 48 h to 19 °C. We suggest that OA and warming trend will threaten the early establishment of this species with further consequences for the functioning of the associated ecosystem.

Graphical abstract

Under laboratory conditions were investigated the combined effect of pCO2, temperature and the exposure time on sorus photosynthetic performance (Fv/Fm) and meiospore performance (release and germination rate) of a habitat-forming kelp Lessonia trabeculata. The results suggest that important traits such as sorus photosynthetic performance, meiospores released and germination rate can be affected by those stressors and by the extent to which the sori are exposed. We concluded that ocean warming and ocean acidification might threaten the early establishment of this species with further consequences for the ecosystem functioning, goods and services in coastal environments.

Continue reading ‘Exposure time modulates the effects of climate change-related stressors on fertile sporophytes and early-life stage performance of a habitat-forming kelp species’

Large-scale interventions may delay decline of the Great Barrier Reef

On the iconic Great Barrier Reef (GBR), the cumulative impacts of tropical cyclones, marine heatwaves and regular outbreaks of coral-eating crown-of-thorns starfish (CoTS) have severely depleted coral cover. Climate change will further exacerbate this situation over the coming decades unless effective interventions are implemented. Evaluating the efficacy of alternative interventions in a complex system experiencing major cumulative impacts can only be achieved through a systems modelling approach. We have evaluated combinations of interventions using a coral reef meta-community model. The model consisted of a dynamic network of 3753 reefs supporting communities of corals and CoTS connected through ocean larval dispersal, and exposed to changing regimes of tropical cyclones, flood plumes, marine heatwaves and ocean acidification. Interventions included reducing flood plume impacts, expanding control of CoTS populations, stabilizing coral rubble, managing solar radiation and introducing heat-tolerant coral strains. Without intervention, all climate scenarios resulted in precipitous declines in GBR coral cover over the next 50 years. The most effective strategies in delaying decline were combinations that protected coral from both predation (CoTS control) and thermal stress (solar radiation management) deployed at large scale. Successful implementation could expand opportunities for climate action, natural adaptation and socioeconomic adjustment by at least one to two decades.

Continue reading ‘Large-scale interventions may delay decline of the Great Barrier Reef’

Impact on fertility rate and embryo-larval development due to the association acidification, ocean warming and lead contamination of a sea urchin Echinometra lucunter (echinodermata: echinoidea)

Ocean warming and acidification can cause deleterious effects on marine biota, which may be potentialized when associated with metal pollution. Thus, the aim of this work was to evaluate the effects of pH decrease, temperature increase and lead contamination on fertility rate and embryo-larval development of Echinometra lucunter. Gametes and embryos were exposed at pH 8.2 (control) and 7.5; at 26°C (control) and 28°C; and at lead concentrations of 0 (control), 125, 250 and 500 μg/L. These conditions were tested individually and in combination. The fertilization rate of E. lucunter was only significantly reduced in the treatments where temperature was increased and in the treatment where pH decreased. However, the development rate of the pluteus larvae was significantly affected in the majority of treatments: metal contamination in the higher concentration; decreased pH in all metal concentrations; increased temperature in the highest metal concentration; decreased pH and increased temperature and all variables combined, which is decreased pH, increased temperature and metal contamination in relation to the control group (C). The development test was shown to be more sensitive than the fertilization test in all the studied scenarios. In general, the present study suggests that pH decrease, temperature increase and metal pollution may have a significant impact on E. lucunter reproductive cycle.

Caetano L. S., Pereira T. M., Envangelista J. D., Cabral D. S., Coppo G. C., Alves de Souza L., Anderson A. B., Heringer O. A. & Chippari-Gomes A. R., in press. Impact on fertility rate and embryo-larval development due to the association acidification, ocean warming and lead contamination of a sea urchin Echinometra lucunter (echinodermata: echinoidea). Bulletin of Environmental Contamination and Toxicology. Article (subscription required).

Cross‐generational response of a tropical sea urchin to global change and a selection event in a 43‐month mesocosm study

Long‐term experimental investigations of transgenerational plasticity (TGP) and transgenerational acclimatization to global change are sparse in marine invertebrates. Here, we test the effect of ocean warming and acidification over a 25‐month period of Echinometra sp. A sea urchins whose parents were acclimatized at ambient or one of two near‐future (projected mid‐ and end‐ of the 21st century) climate scenarios for 18 months. Several parameters linked to performance exhibited strong effects of future ocean conditions at 9 months of age. The Ambient‐Ambient group (A‐A, both F0 and F1 at ambient conditions) was significantly larger (21%) and faster in righting response (31%) compared to other groups. A second set of contrasts revealed near‐future scenarios caused significant negative parental carryover effects. Respiration at 9 months was depressed by 59% when parents were from near‐future climate conditions, and righting response was slowed by 28%. At ten months, a selective pathogenic mortality event lead to significantly higher survival rates of A‐A urchins. Differences in size and respiration measured prior to the mortality were absent after the event, while a negative parental effect on righting (29% reduction) remained. The capacity to spawn at the end of the experiment was higher in individuals with ambient parents (50%) compared to other groups (21%) suggesting persistent parental effects. Obtaining different results at different points in time illustrates the importance of longer‐term and multi‐generation studies to investigate effects of climate change. Given some animals in all groups survived the pathogenic event and that effects on physiology (but not behavior) among groups were eliminated after the mortality, we suggest that similar events could constitute selective sweeps, allowing genetic adaptation. However, given the observed negative parental effects and reduced potential for population replenishment it remains to be determined if selection would be sufficiently rapid to rescue this species from climate change effects.

Continue reading ‘Cross‐generational response of a tropical sea urchin to global change and a selection event in a 43‐month mesocosm study’

Projected near-future ocean acidification decreases mercury toxicity in marine copepods

Highlights

  • Copepods were subjected to OA and Hg pollution under multigenerational exposure.
  • OA reduced Hg accumulation and its toxicity to the growth/reproduction in copepods.
  • Copepod proteome enabled its physiological resilience to decreasing pH.
  • Proteomics indicated many toxic events, ensuring Hg toxicity to the copepod’s traits.
  • Proteome compensation was accounting for the alleviative effect of OA on Hg toxicity.

Abstract

Here, we examined the combinational effect of ocean acidification (OA) and mercury (Hg) in the planktonic copepod Pseudodiaptomus annandalei in cross-factored response to different pCO2 (400, 800 μatm) and Hg (control, 1.0 and 2.5 μg/L) exposures for three generations (F0-F2), followed by single-generation recovery (F3) under clean condition. Several phenotypic traits and Hg accumulation were analyzed for F0-F3. Furthermore, shotgun-based quantitative proteomics was performed for F0 and F2. Our results showed that OA insignificantly influenced the traits. During F0-F2, combined exposure reduced Hg accumulation as compared with the counterpart Hg treatment, supporting the mitigating effect of OA on Hg toxicity in copepods. Proteomics analysis indicated that the copepods probably increased energy production/storage and stress response to ensure physiological resilience against OA. However, Hg induced many toxic events (e.g., energy depletion and degenerated organomorphogenesis/embryogenesis for F0; cell cycle arrest and detrimental stress-defense for F2), which were translated to the population-level adverse outcome, i.e., compromised growth/reproduction. Particularly, compensatory proteome response was identified (e.g., increased immune defense for F0; energetic compensation and enhanced embryogenesis for F2), accounting for a negative interaction between OA and Hg. Together, this study provides the molecular mechanisms behind the effects of OA and Hg pollution in marine copepods.

Continue reading ‘Projected near-future ocean acidification decreases mercury toxicity in marine copepods’

Impacts of plastic-made packaging on marine key species: effects following water acidification and ecological implications

This study evaluates the impacts of 16 different leachates of plastic-made packaging on marine species of different trophic levels (bacteria, algae, echinoderms). Standard ecotoxicological endpoints (inhibition of bioluminescence, inhibition of growth, embryo-toxicity) and alterations of ecologically significant parameters (i.e., echinoderms’ body-size) were measured following exposure under different pH water conditions: marine standard (pH 8.1) and two increasingly acidic conditions (pH 7.8 and 7.5) in order to evaluate possible variations induced by ocean acidification. The results obtained in this study evidence that the tested doses are not able to significantly affect bacteria (Vibrio fischeri) and algae (Phaeodactylum tricornutum). On the contrary, Paracentrotus lividus larvae were significantly affected by several packaging types (13 out of 16) with meaningless differences between pH conditions.

Continue reading ‘Impacts of plastic-made packaging on marine key species: effects following water acidification and ecological implications’

Adult exposure to ocean acidification and warming remains beneficial for oyster larvae following starvation

Climate change is expected to warm and acidify oceans and alter the phenology of phytoplankton, creating a mismatch between larvae and their food. Transgenerational plasticity (TGP) may allow marine species to acclimate to climate change; however, it is expected that this may come with elevated energetic demands. This study used the oysters, Saccostrea glomerata and Crassostrea gigas, to test the effects of adult parental exposure to elevated pCO2 and temperature on larvae during starvation and recovery. It was anticipated that beneficial effects of TGP will be limited when larvae oyster are starved. Transgenerational responses and lipid reserves of larvae were measured for 2 weeks. Larvae of C. gigas and S. glomerata from parents exposed to elevated pCO2 had greater survival when exposed to elevated CO2, but this differed between species and temperature. For S. glomerata, survival of larvae was greatest when the conditions experienced by larvae matched the condition of their parents. For C. gigas, survival of larvae was greater when parents and larvae were exposed to elevated pCO2. Larvae of both species used lipids when starved. The total lipid content was dependent on parental exposure and temperature. Against expectations, the beneficial TGP responses of larvae remained, despite starvation.

Continue reading ‘Adult exposure to ocean acidification and warming remains beneficial for oyster larvae following starvation’

The effects on low pH on sea urchin larval survivorship and development

In recent decades, increasing atmospheric CO2 levels have contributed to the acidification of the world’s oceans. Seawater absorbs CO2 from the atmosphere, which, through a series of chemical reactions, causes an increase in free hydrogen ions and a subsequent decrease in carbonate ions. This adversely affects marine organisms, including sea urchins, since carbonate is critical for building calcium carbonate structures such as shells, without which organisms can die. Declines in urchin populations can have ecological and economic effects, as urchins play critical roles in maintaining ecological balance in marine habitats and are important commercially harvested invertebrates. Larval marine organisms are particularly vulnerable, and increased deformities and mortality are expected in more acidic environments. Therefore, we exposed green sea urchin (Lytechinus variegatus) larvae to different pH levels and examined the effects on development and mortality. Fertilized eggs were reared in seawater with environmentally realistic pH values ranging from pH 7.8 to pH 8.2 (normal seawater), and a larval sample from each treatment was collected every 24 hours for 7 – 10 days. Mortality was documented by counting dead larvae, and development was assessed by comparing morphology among the control and treatment groups. In general, both mortality and morphological abnormalities showed inverse correlations with pH, with the highest mortality rate and most severe abnormalities occurring in larvae exposed to the lowest pH seawater. Larval development was also somewhat delayed in urchin larvae exposed to low pH seawater. These results suggest that acidic seawater, at pH values currently found in the world’s oceans, can adversely affect sea urchin larval development, which can, in turn, have negative ecological and economic consequences.

Continue reading ‘The effects on low pH on sea urchin larval survivorship and development’

Ocean acidification but not elevated spring warming threatens a European Seas predator

Highlights

  • Treatments in marine climate research often ignore important, natural variation
  • Fish embryos were exposed to stable versus warming temperatures (T) and high pCO2
  • Development, hatching and metabolism of a predatory fish (garfish) were examined
  • Increased spring warming benefitted garfish but stable high T and pCO2 were lethal
  • Allospecific prey of garpike have adapted suggesting future, trophodynamic change

Abstract

Ocean acidification has the potential to negatively affect marine ecosystems by influencing the development and metabolism of key members of food webs. The garfish, Belone belone, is an ecologically important predator in European regional seas and it remains unknown how this species will be impacted by projected changes in climate. We artificially fertilized and reared garfish embryos until hatch at present (400 μatm) and future (1300 μatm) pCO2 levels within three temperature treatments, i.e. two daily warming regimes and one constant high temperature (17°C). For the two warming treatments, embryos were fertilized at 13°C and experienced 0.1 or 0.3°C/day warming. The 0.1°C/day treatment served as control: 13°C was the in situ temperature of parental fish in the Southwest Baltic Sea and 0.1°C/day is the average warming rate experienced by embryos of this population in nature. Survival was drastically reduced at both future pCO2 and at the constant high temperature while the highest survival in any treatment was observed at 0.3°C/day warming. The proportion of embryos with morphological deformities increased with elevated pCO2 but not temperature. Hatch characteristics and physiological measures such as heart rate and critical thermal ranges, however, were not affected by pCO2 but were influenced by temperature. Our results suggest that garfish in the Baltic Sea will benefit from projected increased rates of spring warming but not the concomitant increase in pCO2. Previous studies on the impacts of ocean acidification on resident fishes in the Baltic Sea indicate that this piscivorous fish is at higher risk compared to its prey which may have broader implications for the future trophodynamic structure and function of the coastal food web.

Continue reading ‘Ocean acidification but not elevated spring warming threatens a European Seas predator’

Combined effect of microplastics and global warming factors on early growth and development of the sea urchin (Paracentrotus lividus)

Highlights

  • This work focusses on the effect of a multi-stressor environment in sea urchin.
  • Embryo-larval bioassays were used to determine growth and morphometric parameters.
  • A lower water pH (7.6) reduced larval growth and caused deformities.
  • Microplastics aggravate the effect of water acidification in sea urchin larvae.
  • High temperatures caused an additional stress and reduced larvae stomach volume.

Abstract

The aim of this work was to estimate the potential risk of the combined effect of global change factors (acidification, temperature increase) and microplastic (MP) pollution on the growth and development of the sea urchin P. lividus. Embryo-larval bioassays were conducted to determine growth and morphology after 48 h of incubation with MP (1000 and 3000 particles/mL); with filtered sea water at pH = 7.6; and with their combinations. A second experiment was conducted to study the effect of pH and MP in combination with a temperature increase of 4 °C compared to control (20 °C). We found that the inhibition of growth in embryos reared at pH = 7.6 was around 75%. Larvae incubated at 3000 MP particles/mL showed a 20% decrease in growth compared to controls. The exposure to MP also induced an increase in the postoral arm separation or rounded vertices. The combined exposure to a pH 7.6 and MP caused a significant decrease of larval growth compared to control, to MP and to pH 7.6 treatments. Morphological alterations were observed in these treatments, including the development of only two arms. Increasing the temperature resulted in an increased growth in control, in pH 7.6 and pH 7.6 + MP3000 treatments, but the relative stomach volume decreased. However, when growth parameters were expressed per Degree-Days the lower growth provoked by the thermal stress was evidenced in all treatments. In this work we demonstrated that MP could aggravate the effect of a decreased pH and that an increase in water temperature generated an additional stress on P. lividus larvae, manifested in a lower growth and an altered development. Therefore, the combined stress caused by ocean warming, ocean acidification, and microplastic pollution, could threaten sea urchin populations leading to a potential impact on coastal ecosystems.

Continue reading ‘Combined effect of microplastics and global warming factors on early growth and development of the sea urchin (Paracentrotus lividus)’

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Ocean acidification in the IPCC AR5 WG II

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