Posts Tagged 'crustaceans'

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’

pH effects in the acute toxicity study of the crude oil-WAF (water accommodated fraction) in the whiteleg shrimp, Litopenaeus vannamei

Oil spillage can cause harmful risks to marine ecology in a short time period and may lead to devastating long-term impacts. Meanwhile, the trends of a pH decrease due to ocean acidification deteriorate spillages’ impact. This study evaluated the influence of pH on crude oil water accommodated fraction (WAF) toxicity to the whiteleg shrimp, Litopenaeus vannamei. Post larvae of the shrimps were exposed to the crude oil-WAF with concentrations of 0%, 25%, 50%, 75%, and 100% under pH concentrations of 6.5 and 8.5 for 72 hours to quantify their mortality. The polycyclic aromatic hydrocarbons (PAHs) of the WAF were analyzed using the GC-MS method, while the LC50 was determined using probit analysis. L. vannamei showed impaired swimming ability, loss of balance, comatose, and even death when the shrimp were acutely exposed to the crude oil WAF. The 72-h LC50 were slightly lower in pH 6.5 than that of 8.5 (101.7±9.6 mL L-1 and 114.67±11.7 mL L-1 respectively). There were 14 PAH compounds presented in the crude oil-WAF in which carcinogenic compound, benzo[a]pyrene, represented 25% of the total concentration of PAHs. The interaction among PAHs may lead synergistic effects that could increase the mortality of the shrimps. However, based on the US EPA’s LC50 scale, the crude oil-WAF is still practically non-toxic to the whiteleg shrimp, L. vannamei.

Continue reading ‘pH effects in the acute toxicity study of the crude oil-WAF (water accommodated fraction) in the whiteleg shrimp, Litopenaeus vannamei’

Ocean warming and acidification alter Antarctic macroalgal biochemical composition but not amphipod grazer feeding preferences

Increased anthropogenic atmospheric CO2 concentrations have resulted in ocean warming and alterations in ocean carbonate chemistry, decreasing seawater pH (ocean acidification). The combination of ocean warming and acidification (OWA) may alter trophic interactions in marine benthic communities along the western Antarctic Peninsula (WAP). Abundant and diverse macroalgae–grazer assemblages, dominated by macroalgae (e.g. chemically defended Desmarestia anceps and D. menziesii) and gammarid amphipods (e.g. Gondogeneia antarctica), occur on the nearshore benthos along the WAP. In the present study, the amphipod G. antarctica and macroalgae D. anceps and D. menziesii were exposed for 39 and 79 d, respectively, to combinations of current and predicted near-future temperature (1.5 and 3.5°C, respectively) and pH (8.0 and 7.6, respectively). Protein and lipid levels of macroalgal tissues were quantified, and 5-way choice amphipod feeding assays were performed with lyophilized macroalgal tissues collected at time zero and following exposure to the 4 temperature-pH treatments. For D. anceps, we found a significant interactive temperature-pH effect on lipid levels and significantly lower protein levels at reduced pH. In contrast, tissues of D. menziesii exhibited significantly greater lipid levels after exposure to reduced pH, but there was no temperature effect on lipid or protein levels. Despite shifts in macroalgal biochemical composition, there were no changes in amphipod feeding preferences. Our results indicate that despite altered macroalgal nutritional quality under OWA, both macroalgae retained their ability to deter amphipod feeding. This deterrent capacity could become an important contributor to net community resistance of macroalgae-mesograzer assemblages of the WAP to predicted OWA.

Continue reading ‘Ocean warming and acidification alter Antarctic macroalgal biochemical composition but not amphipod grazer feeding preferences’

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’

Ocean acidification causes no detectable effect on swimming activity and body size in a common copepod

Ocean acidification can impair an animal’s physiological performance and energetically demanding activities such as swimming. Behavioural abnormalities and changed activity in response to ocean acidification are reported in fish and crustacean species. We studied swimming activity in the calanoid copepod Pseudocalanus acuspes in response to near-future ocean acidification. Water and copepods were sampled from ten mesocosms deployed on the Swedish west coast. The experiments were conducted on animals reared in the mesocosms for 2 months during spring. Copepods were filmed after long-term (chronic) high-CO2, and after 20 h acute exposure to CO2. There was no significant effect of CO2 on copepods in chronic high-CO2, nor significant effect after the 20 h acute exposure. In addition, we measured prosome length from a large number of adult copepods, but no effect of acidification on body size was found. In this study, P. acuspes did not show sensitivity to near-future pCO2 levels. Even if a number of papers suggest that copepods seem robust to future ocean acidification, interaction between multiple stress factors, such as elevated temperature, hypoxia and salinity changes may impair a copepod’s ability to resist lowered pH.

Continue reading ‘Ocean acidification causes no detectable effect on swimming activity and body size in a common copepod’

Using fuzzy logic to determine the vulnerability of marine species to climate change

Marine species are being impacted by climate change and ocean acidification, although their level of vulnerability varies due to differences in species’ sensitivity, adaptive capacity and exposure to climate hazards. Due to limited data on the biological and ecological attributes of many marine species, as well as inherent uncertainties in the assessment process, climate change vulnerability assessments in the marine environment frequently focus on a limited number of taxa or geographic ranges. As climate change is already impacting marine biodiversity and fisheries, there is an urgent need to expand vulnerability assessment to cover a large number of species and areas. Here, we develop a modelling approach to synthesize data on species-specific estimates of exposure, and ecological and biological traits to undertake an assessment of vulnerability (sensitivity and adaptive capacity) and risk of impacts (combining exposure to hazards and vulnerability) of climate change (including ocean acidification) for global marine fishes and invertebrates. We use a fuzzy logic approach to accommodate the variability in data availability and uncertainties associated with inferring vulnerability levels from climate projections and species’ traits. Applying the approach to estimate the relative vulnerability and risk of impacts of climate change in 1074 exploited marine species globally, we estimated their index of vulnerability and risk of impacts to be on average 52 ± 19 SD and 66 ± 11 SD, scaling from 1 to 100, with 100 being the most vulnerable and highest risk, respectively, under the ‘business-as-usual’ greenhouse gas emission scenario (Representative Concentration Pathway 8.5). We identified 157 species to be highly vulnerable while 294 species are identified as being at high risk of impacts. Species that are most vulnerable tend to be large-bodied endemic species. This study suggests that the fuzzy logic framework can help estimate climate vulnerabilities and risks of exploited marine species using publicly and readily available information.

Continue reading ‘Using fuzzy logic to determine the vulnerability of marine species to climate change’

Homarus gammarus (Crustacea: Decapoda) larvae under an ocean acidification scenario: responses across different levels of biological organization

The present study evaluated the effects of exposure to different target pCO2 levels: control (C: 370μatm, pH = 8.15) and ocean acidification (OA: 710μatm, pH = 7.85) on development and biochemical responses related with oxidative stress and energy metabolism during the crustacean Homarus gammarus (L.) larval development, integrating different levels of biological organization. After hatching in the laboratory, larvae from the same female brood were exposed to the described conditions from hatching until reaching Stage III (last larval stage – 11 days). H. gammarus larvae demonstrated some susceptibility when addressing the predicted pCO2 levels for 2100. Further analysis at the biochemical and physiological level highlighted the occurrence of oxidative stress in the OA scenario (Superoxide Dismutase reduction and higher DNA damage) that was followed by developmental effects, increased inter-moult period from SII to SIII and reduced growth. The extended exposure to these conditions may affect organisms’ key life-cycle functions such as physiological resistance, growth, sexual maturation, or reproduction with implications in their future fitness and population dynamics.

Continue reading ‘Homarus gammarus (Crustacea: Decapoda) larvae under an ocean acidification scenario: responses across different levels of biological organization’


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Ocean acidification in the IPCC AR5 WG II

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