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In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites.

ABSTRACT: Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO2 and ambient pCO2 coral reefs in Papua New Guinea. Echinometra embryos/larvae were reared in meshed chambers moored in arrays on either venting reefs or adjacent non-vent reefs. After 24 and 48 h, larval development and morphology were quantified. Compared with controls (mean pH(T) = 7.89-7.92), larvae developing in elevated pCO2 vent conditions (pH(T) = 7.50-7.72) displayed a significant reduction in size and increased abnormality, with a significant correlation of seawater pH with both larval size and larval asymmetry across all experiments. Reciprocal transplants (embryos from vent adults transplanted to control conditions, and vice versa) were also undertaken to identify if adult acclimatization can translate resilience to offspring (i.e. transgenerational processes). Embryos originating from vent adults were, however, no more tolerant to reduced pH. Sea temperature and chlorophyll-a concentrations (i.e. larval nutrition) did not contribute to difference in larval size, but abnormality was correlated with chlorophyll levels. This study is the first to examine the response of marine larvae to OA scenarios in the natural environment where, importantly, we found that stunted and abnormal development observed in situ are consistent with laboratory observations reported in sea urchins, in both the direction and magnitude of the response.

SUBMITTER: Lamare MD

PROVIDER: S-EPMC5136578 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

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In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites.

Lamare Miles D MD Liddy Michelle M Uthicke Sven S

Proceedings. Biological sciences 20161101 1843

Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO<sub>2</sub> and ambient pCO<sub>2</sub> coral reefs in Papua New Guinea. Echinometra embryos/lar ...[more]

PMID: 27903867

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Project description:In this research we present a transcriptomics analysis of the physiological response of a marine calcifier, Strongylocentrotus purpuratus, to ocean acidification, a decline in ocean pH that results from the absorption of anthropogenic carbon dioxide (CO2). Larvae were raised from fertilization to prism stage in seawater with elevated CO2 conditions based upon IPCC emissions scenario B1 (540ppm CO2) and A1FI (1020ppm CO2). Adult S. purpuratus were collected using SCUBA from Goleta Pier (Goleta,CA, USA) and maintained in flowing seawater tables at 15-16°C. Spawning was induced by coelomic injection of 0.5M KCl following standard methods (Strathmann 1987). Eggs were collected from 3 females and separately fertilized by sperm from a single male (i.e. all larvae were full or half-siblings). Each of the three replicate cultures were divided in three (nine cultures total) and held in 10L flow-through containers filled with seawater aerated through a side arm with commercially manufactured air containing three different pCO2: 380ppm CO2 (present day atmospheric CO2 level, pH 8.01 ± 0.01), 540ppm CO2, an optimistic atmospheric CO2 concentration predicted by the Intergovernmental Panel on Climate Change for 2100 (B1 scenario, pH 7.96 ± 0.01) and 1020ppm CO2 (A1FI scenario, pH 7.88 ± 0.01). Larvae were cultured at 15°C until prism stage (40h post-fertilization). At the 40 hour time point, a sample of 60,000 larvae was removed from each of the 9 cultures in the 380, 540 and 1020 ppm treatments and stored in 1 mL Trizol at -80 ºC for later RNA analysis. The larval cDNA sample from each replicate 540ppm CO2 culture was competitively hybridized against the 380ppm CO2 control culture from the same replicate female. Similarly, the larval cDNA sample from each replicate 1020ppm CO2 culture was competitively hybridized against the 380ppm CO2 control culture from the same replicate female. Using dye swaps of technical replicates, treatment effects could be estimated independently of dye effects.

Project description:Using standard morphometric methods and gene expression profiling with a DNA microarray, we explored the impacts of high CO2 conditions on development of the sea urchin, Lytechinus pictus, a pelagic larvae that forms a calcium carbonate endoskeleton. Larvae were raised from fertilization to pluteus stage in seawater with elevated CO2 conditions based upon IPCC emissions scenarios B1 (540ppm CO2) and A1FI (970ppm CO2). Larval L. pictus were cultured in seawater treated with three different concentrations of CO2. We aerated water in culture chambers with air that had been mixed to different CO2 concentrations chosen from IPCC predictions of future atmospheric CO2 levels (28). The B1 scenario, one of the most optimistic, predicts a stabilization of atmospheric CO2 levels at ~540 ppm by 2100, and the A1F1 scenario, which, reflecting a more âbusiness as usualâ scenario, predicts atmospheric CO2 levels of ~970 ppm by 2100. Compressed air (~380 ppm CO2) was used as a control condition. The culture chambers were 20 L buckets medified to allow aeration bubbles of the experimental gas to mix with and gently stir the culture water without contacting the larvae. Replacement seawater (0.35 Î¼m filtered) was added at a constant rate of 0.5 L hr-1. Water pH of each chamber was monitored daily using a Radiometer Analytical PHM240 pH meter. Adult L. pictus were maintained in flowing seawater at ambient temperature (~15-18 ÂºC) and fed kelp until use. Spawning was induced by coelomic injection of 0.5 M KCl, and eggs were collected in 0.35 Î¼m-filtered seawater. Eggs from 5 females were combined in approximately equal concentrations. Sperm from a single male was collected in the same way, diluted with filtered seawater and added to the egg mixture; thus, all the larvae are half-siblings. Immediately following fertilization, embryos were split into 12 culture chambers providing four replicates of the three CO2 treatments. At the 48 hour time point, a sample of 40,000 larvae was removed from each of the 8 cultures in the 380 and 970 ppm treatments and stored in1 mL Trizol at -80 ÂºC for later RNA analysis. The larval cDNA samples from each treatment were competitively hybridized on each microarray following a balanced incomplete block design (BIBD) with respect to the assignment of treatments to arrays. In this way, differential expression between all pairs of treatments is estimated with equal precision. Although dye swaps of technical replicates were not used, treatment and dye effects are orthogonal to one another, i.e. treatment effects can be estimated independently of dye effects.

Dataset Information

In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites.

Publications

In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites.

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