Posts Tagged 'reproduction'

The effects of in-vitro pH decrease on the gametogenesis of the red tree coral, Primnoa pacifica

Primnoa pacifica is the most ecologically important coral species in the North Pacific Ocean and provides important habitat for commercially important fish and invertebrates. Ocean acidification (OA) is more rapidly increasing in high-latitude seas because anthropogenic CO2 uptake is greater in these regions. This is due to the solubility of CO2 in cold water and the reduced buffering capacity and low alkalinity of colder waters. Primnoa pacifica colonies were cultured for six to nine months in either pH 7.55 (predicted Year 2100 pH levels) or pH 7.75 (Control). Oocyte development and fecundity in females, and spermatocyst stages in males were measured to assess the effects of pH on gametogenesis. Oocyte diameters were 13.6% smaller and fecundities were 30.9% lower in the Year 2100 samples. A higher proportion of vitellogenic oocytes (65%) were also reabsorbed (oosorption) in the Year 2100 treatment. Lower pH appeared to advance the process of spermatogenesis with a higher percentage of later stage sperm compared to Control. There was a laboratory effect observed in all measurement types, however this only significantly affected the analyses of spermatogenesis. Based on the negative effect of acidification on oogenesis and increased rate of oosorption, successful spawning could be unlikely in an acidified ocean. If female gametes were spawned, they are likely to be insufficiently equipped to develop normally, based on the decreased overall size and therefore subsequent limited amount of lipids necessary for successful larval development.

Continue reading ‘The effects of in-vitro pH decrease on the gametogenesis of the red tree coral, Primnoa pacifica’

Larval development, juvenile survival, and burrowing rate of geoduck clams (Panopea japonica) under different pH conditions

Changes in seawater pH in the culture environment have numerous effects on marine bivalves. To investigate the effect of pH on larval development, juvenile survival, and burrowing rate of geoduck clams (Panopea japonica), specimens were cultured under different experimental pH conditions (6.8, 7.2, 7.6, 8.0, 8.4, and 9.2). The pH range for optimal growth and development differed among different larval stages. However, significant changes in larval development (p < 0.5) relative to the control (pH 8.0) were detected at very high or low pH. The best hatching rate occurred at pH 7.6–8.8, and it was significantly lower (p < 0.5) at pH 6.8, 7.2, and 9.2. Larval survival was only 4% at pH 6.8. Growth rate of larvae increased with increasing pH and the optimal range was 8.0 to 8.8. This finding suggests that alkaline conditions favor growth and development of larvae and allow them to reach the metamorphic stage promptly. Prolonged metamorphosis was a common feature in larvae in the different experimental pH groups. pH below 7.6 and above 8.8 resulted in a significantly (p < 0.5) lower metamorphosis rate, suggesting that high acidity and alkalinity were deleterious to larval metamorphosis. Thus, the suitable pH range for metamorphosis was 8.0 to 8.8. Lower and higher pH also affected the digging behavior of geoduck clams, and the suitable pH range for burrowing was 7.2 to 8.8. Geoduck clams stopped burrowing in the sand at pH 6.8 and 9.2, possibly due to impairment of biological process caused by acidic and alkaline seawater. These findings provide valuable information about the larval and juvenile responses of P. japonica in variable pH.

Continue reading ‘Larval development, juvenile survival, and burrowing rate of geoduck clams (Panopea japonica) under different pH conditions’

Systematic review and meta-analysis toward synthesis of thresholds of ocean acidification impacts on calcifying pteropods and interactions with warming

Interpreting the vulnerability of pelagic calcifiers to ocean acidification (OA) is enhanced by an understanding of their critical thresholds and how these thresholds are modified by other climate change stressors (e.g., warming). To address this need, we undertook a three-part data synthesis for pteropods, one of the calcifying zooplankton group. We conducted the first meta-analysis and threshold analysis of literature characterizing pteropod responses to OA and warming by synthetizing dataset comprising of 2,097 datapoints. Meta-analysis revealed the extent to which responses among studies conducted on differing life stages and disparate geographies could be integrated into a common analysis. The results demonstrated reduced calcification, growth, development, and survival to OA with increased magnitude of sensitivity in the early life stages, under prolonged duration, and with the concurrent exposure of OA and warming, but not species-specific sensitivity. Second, breakpoint analyses identified OA thresholds for several endpoints: dissolution (mild and severe), calcification, egg development, shell growth, and survival. Finally, consensus by a panel of pteropod experts was used to verify thresholds and assign confidence scores for five endpoints with a sufficient signal: noise ratio to develop life-stage specific, duration-dependent thresholds. The range of aragonite saturation state from 1.5–0.9 provides a risk range from early warning to lethal impacts, thus providing a rigorous basis for vulnerability assessments to guide climate change management responses, including an evaluation of the efficacy of local pollution management. In addition, meta-analyses with OA, and warming shows increased vulnerability in two pteropod processes, i.e., shell dissolution and survival, and thus pointing toward increased threshold sensitivity under combined stressor effect.

Continue reading ‘Systematic review and meta-analysis toward synthesis of thresholds of ocean acidification impacts on calcifying pteropods and interactions with warming’

Transgenerational effects in an ecological context: conditioning of adult sea urchins to upwelling conditions alters maternal provisioning and progeny phenotype

Highlights

• Differential maternal conditioning did not affect egg size or protein content.

• Simulated upwelling conditions increased maternal provisioning of lipids to eggs.

• Maternal conditioning to simulated upwelling increased embryo body size.

Abstract

Transgenerational plasticity occurs when the conditions experienced by the parental generation influence the phenotype of their progeny. This may in turn affect progeny performance and physiological tolerance, providing a means by which organisms cope with rapid environmental change. We conditioned adult purple sea urchins, Strongylocentrotus purpuratus, to combined pCO2 and temperature conditions reflective of in situ conditions of their natural habitat, the benthos in kelp forests of nearshore California, and then assessed the performance of their progeny raised under different pCO2 levels. Adults were conditioned during gametogenesis to treatments that reflected static non-upwelling (~650 μatm pCO2, ~17 °C) and upwelling (~1300 μatm pCO2, ~13 °C) conditions. Following approximately 4 months of conditioning, the adults were spawned and embryos were raised under low pCO2 (~450 μatm pCO2) or high pCO2 (~1050 μatm pCO2) treatments to determine if differential maternal conditioning impacted the progeny response to a single abiotic stressor: pCO2. We examined the size, protein content, and lipid content of eggs from both sets of conditioned female urchins. Offspring were sampled at four stages of early development: hatched blastula, gastrula, prism, and echinopluteus. This resulted in four sets of offspring: (1) progeny from non-upwelling-conditioned mothers raised under low pCO2, (2) progeny from non-upwelling-conditioned mothers raised under high pCO2, (3) progeny from upwelling-conditioned mothers raised under low pCO2, and (4) progeny from upwelling-conditioned mothers raised under high pCO2. We then assessed the effects of maternal conditioning along with the effects of developmental pCO2 levels on body size of the progeny. Our results showed that differential maternal conditioning had no impact on average egg size, although non-upwelling females produced eggs that were more variable in size. Maternal conditioning did not affect protein content but did have a modest impact on egg lipid content. Developing embryos whose mothers were conditioned to simulated upwelling conditions (~1300 μatm pCO2, ~13 °C) were greater in body size, although this effect was no longer evident at the echinopluteus larval stage. Although maternal conditioning affected offspring body size, the pCO2 levels under which the embryos were raised did not. Overall, this laboratory study provides insight into how transgenerational effects may function in nature. The impacts of parental environmental history on progeny phenotype during early development have important implications regarding recruitment success and population-level effects.

Continue reading ‘Transgenerational effects in an ecological context: conditioning of adult sea urchins to upwelling conditions alters maternal provisioning and progeny phenotype’

Legacy of multiple stressors: responses of gastropod larvae and juveniles to ocean acidification and nutrition

Ocean acidification poses a significant threat to calcifying invertebrates by negatively influencing shell deposition and growth. An organism’s performance under ocean acidification is not determined by the susceptibility of one single life-history stage, nor is it solely controlled by the direct physical consequences of ocean acidification. Shell development by one life-history stage is sometimes a function of the pH or pCO2 levels experienced during earlier developmental stages. Furthermore, environmental factors such as access to nutrition can buffer organismal responses of calcifying invertebrates to ocean acidification, or they can function as a co-occurring stressor when access is low. We reared larvae and juveniles of the planktotrophic marine gastropod Crepidula fornicata through combined treatments of nutritional stress and low pH, and we monitored how multiple stressors endured during the larval stage affected juvenile performance. Shell growth responded non-linearly to decreasing pH, significantly declining between pH 7.6 and pH 7.5 in larvae and juveniles. Larval rearing at pH 7.5 reduced juvenile growth as a carryover effect. Larval rearing at pH 7.6 reduced subsequent juvenile growth despite the absence of a negative impact on larval growth, demonstrating a latent effect. Low larval pH magnified the impact of larval nutritional stress on competence for metamorphosis and increased carryover effects of larval nutrition on juvenile growth. Trans-life-cycle effects of larval nutrition were thus modulated by larval exposure to ocean acidification.

Continue reading ‘Legacy of multiple stressors: responses of gastropod larvae and juveniles to ocean acidification and nutrition’

The dynamic ocean acidification manipulation experimental system: Separating carbonate variables and simulating natural variability in laboratory flow‐through experiments

Carbonate chemistry variables such as PCO2, pH, and mineral saturation state (Ω) are commonly thought of as covarying in open‐ocean settings but have decoupled over geologic time‐scales and among modern dynamic coastal margins and estuaries. Predicting responses of vulnerable coastal organisms to past, present, and future ocean acidification (OA) scenarios requires the empirical identification of organismal sensitivity thresholds to individual carbonate chemistry parameters. Conversely, most OA experiments involve chemistry manipulations that result in covariance of carbonate system variables. We developed the Dynamic Ocean Acidification Manipulation Experimental System (DOAMES)—a feed‐forward, flow‐through carbonate chemistry control system capable of decoupling PCO2, pH, or Ω by independently manipulating total alkalinity (TAlk) and total inorganic carbon (TCO2). DOAMES proof‐of‐concept can manipulate source seawater with stable or variable carbonate chemistry and produce experimental treatments with constant and dynamic carbonate chemistry regimes. The combination of dynamic input and output allows for offset treatments that impose a ΔPCO2 on naturally variable conditions. After overcoming several operational challenges, DOAMES is capable of simultaneously generating three different experimental treatments within 1% ± 1% of TCO2 and TAlk targets. The achieved precision and accuracy resulted in the successful decoupling of pH and ΩAr in five trials. We tested the viability of sensitive bivalve embryos raised in DOAMES‐manipulated seawater and found no difference in development when compared to the control, demonstrating DOAMES suitability for organismal studies. DOAMES provides a novel tool to evaluate organismal effects of exposure to decoupled carbonate system variables and to past, current, and future carbonate chemistry scenarios.

Continue reading ‘The dynamic ocean acidification manipulation experimental system: Separating carbonate variables and simulating natural variability in laboratory flow‐through experiments’

CO2 leakage simulation: effects of the decreasing pH to the survival and reproduction of two crustacean species

Highlights

• Both species show reduction in their fitness when exposed to CO2 acidification scenarios.

• The isopod Cyathura carinata survives at pH as low as 6.5, not the amphipod Elasmopus rapax

• The impairment observed in E. rapax was more severe than in C. carinata.

• Regardless the lengths of the lifespan, both species were unable to produce offspring.

Abstract

The effects of CO2-related acidification on two crustacean populations, the isopod Cyathura carinata and the amphipod Elasmopus rapax, were studied. Three pH levels were tested: artificial seawater without CO2 injection and two levels of reduced pH. Even though RNA:DNA ratio was reduced for both species, no statistical significant differences were found between the control and the treatments. Both species experienced a reduction in survivorship, longevity and the body length of surviving animals; although the impairment observed in E. rapax was more severe than in C. carinata. The long life span isopod and the short life span amphipod experienced a high degree of impairment in the reproduction, likely due to the reallocation of resources from reproduction to body maintenance and increasing survival by postponing the brood production. Regardless of the underlying processes and the energetic pathways, both experienced failure to reproduce, which could lead to the local extinction of these species.

Continue reading ‘CO2 leakage simulation: effects of the decreasing pH to the survival and reproduction of two crustacean species’


Subscribe to the RSS feed

Powered by FeedBurner

Follow AnneMarin on Twitter

Blog Stats

  • 1,242,908 hits

OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book