Posts Tagged 'reproduction'

Effects of high pCO2 on early life development of pelagic spawning marine fish

The present study investigated the effect of elevated pCO2 on the development of early stages of the pelagic spawning marine fish Solea senegalensis, Diplodus sargus and Argyrosomus regius. Eggs and larvae were reared under control (pH 8.0, ~570 μatm) and two elevated pCO2 conditions (pH 7.8, ~1100 μatm; pH 7.6, ~1900 μatm) until mouth opening (3 days post-hatching). Egg size did not change with exposure to elevated pCO2, but hatching rate was significantly reduced under high pCO2 for all three species. Survival rate was not affected by exposure to increased pCO2, but growth rate was differently affected across species, with A. regius growing faster in the mid-level pCO2 treatment compared with control conditions. S. senegalensis and A. regius hatched with smaller yolk sacs under increased pCO2 but endogenous reserves of D. sargus were not affected. Otoliths were consistently larger under elevated pCO2 conditions for all the three species. Differences among egg batches and a significant interaction between batch and pCO2 suggest that other factors, such as egg quality, can influence the response to increased pCO2. Overall, the results support the occurrence of a species-specific response to pCO2, but highlight the need for cautious analysis of potential sensitivity of species from unreplicated observations.

Continue reading ‘Effects of high pCO2 on early life development of pelagic spawning marine fish’

Effects of pH and temperature on egg hatching success of the marine planktonic copepod, Calanus finmarchicus

Calanus finmarchicus is a predominant planktonic copepod in the northern North Atlantic Ocean, where it is a fundamental link in the transfer of energy from phytoplankton to fish. Here, we investigate whether ocean acidification at present-day and future levels will cause a significant decrease in the egg hatching success (HS) of C. finmarchicus in the Gulf of Maine. Eggs spawned by female C. finmarchicus collected from the coastal Gulf of Maine were incubated in seawater acidified by addition of CO2 to selected pH levels at 3.5 °C (in a single experiment), 6 °C and 14–15 °C (in multiple experiments). HS was unaffected by pH between 6.58 and 8.0 at 3.5 and 6 °C, and between 7.1 and 8.0 when incubated at 15 °C. A significant interactive effect between temperature and pH on HS was found using a two-way ANOVA of the data from experiments at 6 °C and 14–15 °C, temperatures that are experienced in summer in the Gulf of Maine. HS of eggs spawned from C. finmarchicus females immediately after capture from a coastal station was significantly reduced at pH ≤ 7.0 when incubated at 14–15 °C, although HS of eggs collected from well-fed females in the laboratory in water from the Damariscotta Estuary was not significantly reduced at pH levels as low as 6.6 at 15 °C. This finding is consistent with the hypothesis that parental history and possibly maternal provisioning can influence capability of eggs to adjust to lower pH environments. While an interaction between pH and temperatures experienced by C. finmarchicus at the southern edge of its biogeographic range was observed, the pH at which this interaction occurred is substantially lower than pH levels predicted for the surface ocean over the surface ocean.

Continue reading ‘Effects of pH and temperature on egg hatching success of the marine planktonic copepod, Calanus finmarchicus’

Reproductive and trans-generational effect of ocean acidification and warming on the coral Stylophora pistillata in the Gulf of Aqaba

Global warming is threatening 75 % of the world’s coral reefs. The reproduction of corals is a driver for the development of the whole reef ecosystem. Then, it is essential to better understand the transgenerational mechanisms in the response of parents and offspring to elevated temperature and lowered pH. Colonies of Stylophora pistillata from the Gulf of Aqaba during their reproduction period were exposed to a 4°C increase in temperature and a pH of 7.6 for 36 days, then a 6°C increase for six days. Planulae were counted on seven consecutive nights, two times during the experiment period. Physiological characteristics of adult and planulae were assessed on four and five sampling points respectively, as well as the behaviour of the planulae through their incubation. Results show no effect of OWA on the reproduction, parents, and planulae physiology. They suggest that the natural resistance of corals in the Gulf of Aqaba is transmitted from parent to offspring. Data on planulae quantity, survival, settlement, and metabolism provides additional and useful information to understand the biology of this coral, specially in its early-life stage. This study’s outcome is adding evidences of the future development of corals reefs in this region, unlike several other tropical reefs in the world.

Continue reading ‘Reproductive and trans-generational effect of ocean acidification and warming on the coral Stylophora pistillata in the Gulf of Aqaba’

Increased temperature mitigates the effects of ocean acidification on the calcification of juvenile Pocillopora damicornis, but at a cost

This study tested the interactive effects of increased seawater temperature and CO2 partial pressure (pCO2) on the photochemistry, bleaching, and early growth of the reef coral Pocillopora damicornis. New recruits were maintained at ambient or high temperature (29 or 30.8 °C) and pCO2 (~ 500 and ~ 1100 μatm) in a full-factorial experiment for 3 weeks. Neither a sharp decline in photochemical efficiency (Fv/Fm) nor evident bleaching was observed at high temperature and/or high pCO2. Furthermore, elevated temperature greatly promoted lateral growth and calcification, while polyp budding exhibited temperature-dependent responses to pCO2. High pCO2 depressed calcification by 28% at ambient temperature, but did not impact calcification at 30.8 °C. Interestingly, elevated temperature in concert with high pCO2 significantly retarded the budding process. These results suggest that increased temperature can mitigate the adverse effects of acidification on the calcification of juvenile P. damicornis, but at a substantial cost to asexual budding.

Continue reading ‘Increased temperature mitigates the effects of ocean acidification on the calcification of juvenile Pocillopora damicornis, but at a cost’

Oyster reproduction is compromised by acidification experienced seasonally in coastal regions

Atmospheric carbon dioxide concentrations have been rising during the past century, leading to ocean acidification (OA). Coastal and estuarine habitats experience annual pH variability that vastly exceeds the magnitude of long-term projections in open ocean regions. Eastern oyster (Crassostrea virginica) reproduction season coincides with periods of low pH occurrence in estuaries, thus we investigated effects of moderate (pH 7.5, pCO2 2260 µatm) and severe OA (pH 7.1, pCO2 5584 µatm; and 6.7, pCO2 18480 µatm) on oyster gametogenesis, fertilization, and early larval development successes. Exposure at severe OA during gametogenesis caused disruption in oyster reproduction. Oogenesis appeared to be more sensitive compared to spermatogenesis. However, Eastern oyster reproduction was resilient to moderate OA projected for the near-future. In the context of projected climate change exacerbating seasonal acidification, OA of coastal habitats could represent a significant bottleneck for oyster reproduction which may have profound negative implications for coastal ecosystems reliant on this keystone species.

Continue reading ‘Oyster reproduction is compromised by acidification experienced seasonally in coastal regions’

Exposure to elevated pCO2 does not exacerbate reproductive suppression of Aurelia aurita jellyfish polyps in low oxygen environments

Eutrophication-induced hypoxia is one of the primary anthropogenic threats to coastal ecosystems. Under hypoxic conditions, a deficit of O2 and a surplus of CO2 will concurrently decrease pH, yet studies of hypoxia have seldom considered the potential interactions with elevated pCO2 (reduced pH). Previous studies on gelatinous organisms concluded that they are fairly robust to low oxygen and reduced pH conditions individually, yet the combination of stressors has only been examined for ephyrae. The goals of this study were to determine the individual and interactive effects of hypoxia and elevated pCO2 on the asexual reproduction and aerobic respiration rates of polyps of the scyphozoan Aurelia aurita during a manipulative experiment that ran for 36 d. pCO2 and pO2 were varied on a diel basis to closely mimic the diel conditions observed in the field. Exposure to low dissolved oxygen (DO) reduced asexual budding of polyps by ~50% relative to control conditions. Under hypoxic conditions, rates of respiration were elevated during an initial acclimation period (until Day 8), but respiration rates did not differ between DO levels under prolonged exposure. There was no significant effect of increased pCO2 on either asexual reproduction or aerobic respiration, suggesting that elevated pCO2 (reduced pH) did not exacerbate the negative reproductive effects of hypoxia on A. aurita polyps.

Continue reading ‘Exposure to elevated pCO2 does not exacerbate reproductive suppression of Aurelia aurita jellyfish polyps in low oxygen environments’

Effects of in situ CO2 enrichment on epibiont settlement on artificial substrata within a Posidonia oceanica meadow

Highlights

  • Ocean acidification (OA) may cause community shifts by effecting early life stages.
  • pH was lowered in situ and maintained as an offset within a FOCE setup.
  • Settlement/colonization of molluscs and peracarid crustaceans were robust to OA.
  • Crustose coralline algae and calcifying polychaetes were vulnerable at early life.

Abstract

Alterations to colonization or early post-settlement stages may cause the reorganization of communities under future ocean acidification conditions. Yet, this hypothesis has been little tested by in situ pH manipulation. A Free Ocean Carbon Dioxide Enrichment (FOCE) system was used to lower pH by a ~ 0.3 unit offset within a partially enclosed portion (1.7 m3) of a Posidonia oceanica seagrass meadow (11 m depth) between 21 June and 3 November 2014. Epibiont colonization and early post settlement stages were assessed within the FOCE setup, as part of the larger community-level study, to better understand the outcome for a multispecies assemblage and the ecological processes that result in reported community shifts under altered carbonate chemistry. Two types of artificial collectors (tiles and scourers) were placed within three treatments: a pH-manipulated enclosure, an un-manipulated control enclosure, and an open plot in the ambient meadow. Tiles and scourers were collected after one to four months. Additionally, to see whether the outcome differed for communities in a later successional stage, previously settled scourer-collectors were also placed in the same three treatments. Enclosures acted to reduce settlement and migrant colonization. Scourers deployed for one to four months within the open-plot contained a community assemblage that could be distinguished from the assemblages within the enclosures. However, a comparison of enclosure assemblages on tiles showed evidence of a pH effect. There was lowered coverage of crustose coralline algae and fewer calcareous tube-forming polychaetes (Spirorbis sp. and Spirobranchus sp.) on tiles placed in the pH-manipulated enclosure compared to the un-manipulated enclosure. For assemblages in scourer collectors, shared and common taxa, in all treatments, were invertebrate polychaetes Psamathe fusca, Sphaerosyllis sp., Chrysopetalum sp., arthropods Harpacticoida, and Amphipoda, and the juvenile bivalve Lyonsia sp. Similar organism composition and abundance, as well as taxonomic richness and evenness, were found in scourers from both enclosures. Pre-settled scourers contained greater numbers of individuals and more calcified members, but the assemblage, as well as the growth rate of a juvenile bivalve Lyonsia sp., appeared unaffected by a two-month exposure to lowered pH and calcium carbonate saturation state. Results from this case study support the hypothesis that early stages of specific calcifiers (crustose coralline algae and calcareous tube-forming polychaetes) are sensitive to near future ocean acidification conditions yet suggest that negative effects on sessile micro-invertebrate assemblages will be minimal.

Continue reading ‘Effects of in situ CO2 enrichment on epibiont settlement on artificial substrata within a Posidonia oceanica meadow’


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Ocean acidification in the IPCC AR5 WG II

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