Dataset Information

Variation in sensitivity of large benthic Foraminifera to the combined effects of ocean warming and local impacts.

ABSTRACT: Large benthic foraminifera (LBF) are crucial marine calcifiers in coral reefs, and sensitive to environmental changes. Yet, many species successfully colonise a wide range of habitats including highly fluctuating environments. We tested the combined effects of ocean warming, local impacts and different light levels on populations of the common LBF Amphistegina lobifera collected along a cross-shelf gradient of temperature and nutrients fluctuations. We analysed survivorship, bleaching frequency, chlorophyll a content and fecundity. Elevated temperature and nitrate significantly reduced survivorship and fecundity of A. lobifera across populations studied. This pattern was exacerbated when combined with below optimum light levels. Inshore populations showed a consistent resistance to increased temperature and nitrate levels, but all populations studied were significantly affected by light reduction. These findings demonstrated the capacity of some populations of LBF to acclimate to local conditions; nonetheless improvements in local water quality can ultimately ameliorate effects of climate change in local LBF populations.

SUBMITTER: Prazeres M

PROVIDER: S-EPMC5362903 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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Variation in sensitivity of large benthic Foraminifera to the combined effects of ocean warming and local impacts.

Prazeres Martina M Roberts T Edward TE Pandolfi John M JM

Scientific reports 20170323

Large benthic foraminifera (LBF) are crucial marine calcifiers in coral reefs, and sensitive to environmental changes. Yet, many species successfully colonise a wide range of habitats including highly fluctuating environments. We tested the combined effects of ocean warming, local impacts and different light levels on populations of the common LBF Amphistegina lobifera collected along a cross-shelf gradient of temperature and nutrients fluctuations. We analysed survivorship, bleaching frequency, ...[more]

PMID: 28332634

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Project description:The association with photosymbiotic algae is crucial for the proliferation of many coral reef organisms, but increases their sensitivity to environmental changes. Large benthic foraminifera (LBF) are a diverse group of carbonate producers harboring algal photosymbionts. They act as key ecological engineers and are widely used as bioindicators. As in corals, elevated temperatures and light intensities are known to induce bleaching in LBF, but the combined effects of ocean acidification and warming remain unclear. To shed light into the adaptive physiology of LBF, we linked the assessment of the holobiont and photosymbiont physiological condition (mortality, growth, coloration, and chlorophyll a) to a bottom-up proteomics approach that allows the examination of cellular responses of host and symbionts simultaneously. In a two-months experiment, we exposed Amphistegina lobifera to the combined effects of ocean acidification (400, 1000 and 2800 ppm pCO2) and warming (28-control and 31°C). More than 1,000 proteins were identified by label-free mass spectrometry-based whole proteome analysis and assigned to the host or photosymbionts. Photopigment concentrations declined in response to elevated pCO2, visible by discoloration. These indicate the reduction of photosymbiont densities under ocean acidification, despite the fertilizing effects suggested for high inorganic carbon availability, and imply metabolic adjustments. Increases of proteolytic proteins suggest active host regulation of photosymbiont density in order to maintain homeostasis with its algal photosymbionts. Growth rates, however, were unaffected by elevated pCO2 levels at control temperatures, but high pCO2 levels (2800 ppm, pH 7.52) combined with thermal stress (31°C) impaired growth, though mortality and shell dissolution was negligible. While growth was unaffected by intermediate pCO2 levels (1000 ppm, pH 7.98) combined with ocean warming, this treatment induced the most distinct proteome responses. These include the regulation of ion transporters and host cytoplasmic proteins that likely abet calcification under ocean acidification. This study reveals a highly complex cellular response in both the host and the photosymbiont, which appears to facilitate a high resilience potential of A. lobifera to end of the century ocean conditions. Nevertheless, our results imply that when pCO2 levels rise above 1000 ppm during persistent ocean warming or extreme heating events these adaptive mechanisms become disrupted.

Project description:The Antarctic coastal fauna is characterized by high endemism related to the progressive cooling of Antarctic waters and their isolation by the Antarctic Circumpolar Current. The origin of the Antarctic coastal fauna could involve either colonization from adjoining deep-sea areas or migration through the Drake Passage from sub-Antarctic areas. Here, we tested these hypotheses by comparing the morphology and genetics of benthic foraminifera collected from Antarctica, sub-Antarctic coastal settings in South Georgia, the Falkland Islands and Patagonian fjords. We analyzed four genera (Cassidulina, Globocassidulina, Cassidulinoides, Ehrenbergina) of the family Cassidulinidae that are represented by at least nine species in our samples. Focusing on the genera Globocassidulina and Cassidulinoides, our results showed that the first split between sub-Antarctic and Antarctic lineages took place during the mid-Miocene climate reorganization, probably about 20 to 17 million years ago (Ma). It was followed by a divergence between Antarctic species ~ 10 Ma, probably related to the cooling of deep water and vertical structuring of the water-column, as well as broadening and deepening of the continental shelf. The gene flow across the Drake Passage, as well as between South America and South Georgia, seems to have occurred from the Late Miocene to the Early Pliocene. It appears that climate warming during 7-5 Ma and the migration of the Polar Front breached biogeographic barriers and facilitated inter-species hybridization. The latest radiation coincided with glacial intensification (~ 2 Ma), which accelerated geographic fragmentation of populations, demographic changes, and genetic diversification in Antarctic species. Our results show that the evolution of Antarctic and sub-Antarctic coastal benthic foraminifera was linked to the tectonic and climatic history of the area, but their evolutionary response was not uniform and reflected species-specific ecological adaptations that influenced the dispersal patterns and biogeography of each species in different ways.

Project description:Rising ocean temperatures are threatening marine species and populations worldwide, and ectothermic taxa are particularly vulnerable. Echinoderms are an ecologically important phylum of marine ectotherms and shifts in their population dynamics can have profound impacts on the marine environment. The effects of warming on echinoderms are highly variable across controlled laboratory-based studies. Accordingly, synthesis of these studies will facilitate the better understanding of broad patterns in responses of echinoderms to ocean warming. Herein, a meta-analysis incorporating the results of 85 studies (710 individual responses) is presented, exploring the effects of warming on various performance predictors. The mean responses of echinoderms to all magnitudes of warming were compared across multiple biological responses, ontogenetic life stages, taxonomic classes, and regions, facilitated by multivariate linear mixed effects models. Further models were conducted, which only incorporated responses to warming greater than the projected end-of-century mean annual temperatures at the collection sites. This meta-analysis provides evidence that ocean warming will generally accelerate metabolic rate (+32%) and reduce survival (-35%) in echinoderms, and echinoderms from subtropical (-9%) and tropical (-8%) regions will be the most vulnerable. The relatively high vulnerability of echinoderm larvae to warming (-20%) indicates that this life stage may be a significant developmental bottleneck in the near-future, likely reducing successful recruitment into populations. Furthermore, asteroids appear to be the class of echinoderms that are most negatively affected by elevated temperature (-30%). When considering only responses to magnitudes of warming representative of end-of-century climate change projections, the negative impacts on asteroids, tropical species and juveniles were exacerbated (-51%, -34% and -40% respectively). The results of these analyses enable better predictions of how keystone and invasive echinoderm species may perform in a warmer ocean, and the possible consequences for populations, communities and ecosystems.

Dataset Information

Variation in sensitivity of large benthic Foraminifera to the combined effects of ocean warming and local impacts.

Publications

Variation in sensitivity of large benthic Foraminifera to the combined effects of ocean warming and local impacts.

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