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1.
PLoS One ; 14(8): e0220046, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31433797

RESUMO

Foraminifera are expected to be particularly susceptible to future changes in ocean carbonate chemistry as a function of increased atmospheric CO2. Studies in an experimental recirculating seawater system were performed with a dominant benthic foraminiferal species collected from intertidal mudflats. We investigated the experimental impacts of ocean acidification on survival, growth/calcification, morphology and the biometric features of a calcareous species Elphidium williamsoni. Foraminifera were exposed for 6 weeks to four different pH treatments that replicated future scenarios of a high CO2 atmosphere resulting in lower seawater pH. Results revealed that declining seawater pH caused a decline in foraminiferal survival rate and growth/calcification (mainly through test weight reduction). Scanning electron microscopy image analysis of live specimens at the end of the experimental period show changes in foraminiferal morphology with clear signs of corrosion and cracking on the test surface, septal bridges, sutures and feeding structures of specimens exposed to the lowest pH conditions. These findings suggest that the morphological changes observed in shell feeding structures may serve to alter: (1) foraminiferal feeding efficiency and their long-term ecological competitiveness, (2) the energy transferred within the benthic food web with a subsequent shift in benthic community structures and (3) carbon cycling and total CaCO3 production, both highly significant processes in coastal waters. These experimental results open-up the possibility of modelling future impacts of ocean acidification on both calcification and dissolution in benthic foraminifera within mid-latitude intertidal environments, with potential implications for understanding the changing marine carbon cycle.


Assuntos
Calcificação Fisiológica/efeitos dos fármacos , Foraminíferos/efeitos dos fármacos , Foraminíferos/crescimento & desenvolvimento , Água do Mar/química , Carbonatos/análise , Carbonatos/farmacologia , Foraminíferos/fisiologia , Concentração de Íons de Hidrogênio , Análise de Sobrevida , Fatores de Tempo
2.
Mar Pollut Bull ; 146: 247-254, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31426153

RESUMO

It is hypothesized that pH fluctuations produced by seagrasses metabolism may confer marine calcifiers resistance to ocean acidification. Here, we tested this thesis by comparing the net population growth rate (NPGR) of a foraminifer species (Rosalina sp.) epiphytic of Mediterranean seagrass (Posidonia oceanica) to average current and projected pH scenarios under either stable conditions or diel fluctuations in pH of 0.3 units; variations similar to that experienced in their habitat. No significant differences were found in NPGRs between the fluctuating and stable pH treatments at current pH levels. NPGRs in treatments where pH fluctuated did not present significant differences to the treatment with high and stable pH conditions. In contrast, foraminifers exposed to stable low pH regimes experienced a steep decline in NPGR. These results suggest that diel pH fluctuations generated by P. oceanica photosynthetic activity could confer resistance to ocean acidification to Rosalina sp.


Assuntos
Alismatales/fisiologia , Foraminíferos/fisiologia , Água do Mar/química , Alismatales/metabolismo , Carbono/metabolismo , Ecossistema , Ecotoxicologia/métodos , Concentração de Íons de Hidrogênio , Fotossíntese
3.
Sci Total Environ ; 651(Pt 1): 261-270, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30236843

RESUMO

Climate change, pollution and increased runoff are some of the main drivers of coral reefs degradation worldwide. However, the occurrence of runoff and marine pollution, as well as its ecological effects in South Atlantic coral reefs are still poorly understood. The aim of the present work is to characterize the terrigenous influence and contamination impact on the environmental health of five reefs located along a gradient of distance from a river source, using geochemical, water quality, and ecological indicators. Stable isotopes and sterols were used as geochemical indicators of sewage and terrigenous organic matter. Dissolved metal concentrations (Cu, Zn, Cd, and Pb) were used as indicators of water quality. Population density, bleaching and chlorophyll α content of the symbiont-bearing foraminifer Amphistegina gibbosa, were used as indicators of ecological effects. Sampling was performed four times during the year to assess temporal variability. Sediment and water quality indicators showed that reefs close to the river discharge experience nutrient enrichment and sewage contamination, and metals concentrations above international environmental quality guidelines. Higher levels of contamination were strongly related to the higher frequency of bleaching and lower density in A. gibbosa populations. The integrated evaluation of stable isotopes, sterols and metals provided a consistent diagnostic about sewage influence on the studied reefs. Additionally, the observed bioindicator responses evidenced relevant ecological effects. The water quality, geochemical and ecological indicators employed in the present study were effective as biomonitoring tools to be applied in reefs worldwide.


Assuntos
Recifes de Corais , Foraminíferos/fisiologia , Metais/efeitos adversos , Esteroides/efeitos adversos , Poluentes Químicos da Água/efeitos adversos , Qualidade da Água , Brasil , Monitoramento Ambiental , Geografia , Densidade Demográfica , Rios
4.
Mar Pollut Bull ; 135: 682-693, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30301086

RESUMO

The aquaculture and industrial sewage impacts on benthic foraminifera investigated at two reefs across the northern Persian Gulf. The foraminifera assemblages at a single sewaged reef were compared with two non-sewaged reefs. A low-diversity assemblage, dominated by stress-tolerant species Quinqueloculina sp. and larger symbiont-bearing Amphistegina sp., was characteristic of the industrial sewaged reef. The opportunistic species Ammonia sp. and Elphidium sp. were common in aquaculture sewaged reef. The density of foraminifera in sewaged reefs was lower than non-sewaged reefs. The lower diversity was only detected in the industrial sewaged reef. Assemblage structure was significantly different between sewaged and non-sewaged reefs. The industrial sewaged reef displayed high FORAM Index values (>4.0), reflecting favorable environments for supporting relatively healthy reefs. FORAM Index in aquaculture sewaged reef ranged from 2.0 to 4.0 indicated that the water with organic pollution may support living coral community, but any damage would not be followed by recovery.


Assuntos
Recifes de Corais , Foraminíferos/fisiologia , Poluição da Água/efeitos adversos , Animais , Antozoários , Aquicultura , Biodiversidade , Biomarcadores Ambientais , Monitoramento Ambiental/métodos , Sedimentos Geológicos , Oceano Índico , Esgotos , Simbiose , Qualidade da Água
5.
Mar Pollut Bull ; 135: 977-987, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30301123

RESUMO

This work tackles a multidisciplinary study on the recent sedimentary record of the Bilbao estuary (northern Spain), which is the backbone of a city that was primarily industrial and now is widely recognized as a successful example of urban transformation. Although hotspots of heavily polluted materials still remain at the mouth of the two main tributaries (Galindo and Gobelas), the data obtained confirm the ongoing formation of a new layer of sediments (here called "postindustrial zone") covering historically polluted and azoic deposits. It is characterized by largely variable levels of metals and magnetic susceptibility and moderate-to-high abundances of benthic foraminifera. Monitoring of the evolution of this layer appears a key factor to assess environmental improvement and decision-making in polluted estuaries.


Assuntos
Monitoramento Ambiental/métodos , Estuários , Foraminíferos/fisiologia , Sedimentos Geológicos/química , Metais/análise , Animais , Organismos Aquáticos , Magnetismo , Paleontologia/métodos , Espanha , Poluentes Químicos da Água/análise
6.
ScientificWorldJournal ; 2018: 6126528, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29988203

RESUMO

Late Cretaceous-Paleocene foraminiferans and palynomorphs were recovered from the upper section of the Djega outcrop in the Rio del Rey Basin. Only a few planktonic foraminiferan species of the genera Heterohelix and Hedbergella were recovered among an assemblage dominated by calcareous and agglutinated benthonics. Marine dinocysts are curiously absent from among the palynomorph assemblage, which consists dominantly of pollen grains from land plants (angiosperms and gymnosperms) and pteridophytic spores, together with a few fungal remains. Two benthonic foraminiferal assemblages that include the Campanian-Maastrichtian Bolivina afra-Haplophragmoides talokensis and the Paleocene Anomalinoides umboniferus-Eponides pseudoelevatus are well established at this outcrop. The palynomorphs include a few typical Late Cretaceous and typical Paleogene species, while the majority are long ranging forms that straddle the Cretaceous-Tertiary boundary. The foraminiferal and palynomorph biostratigraphic distributions permitted us to recognize the succession of Campanian-Maastrichtian and Paleocene strata and the Cretaceous-Tertiary boundary for the first time in this basin. Lithofacies change from a monotonous thick pile of shales below, succeeded by sandstones, frequently alternating with mudstone, above. This indicates a general fall in sea level during the Early Paleocene earlier reported within this subregion, and the boundary marks the start of the out building of the Niger Delta which the Tertiary Rio del Rey Basin is part of. Both microfossils and lithofacies analyses aided the reconstruction of an open marine, probably middle to inner neritic shallow and transitional intertidal paleodepositional environments for the sediments exposed at this outcrop.


Assuntos
Foraminíferos/fisiologia , Camarões , Cycadopsida/fisiologia , Fósseis , Magnoliopsida/fisiologia , Esporos de Protozoários/fisiologia
7.
Proc Biol Sci ; 285(1883)2018 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-30051846

RESUMO

Changes in biodiversity at all levels from molecules to ecosystems are often linked to climate change, which is widely represented univariately by temperature. A global environmental driving mechanism of biodiversity dynamics is thus implied by the strong correlation between temperature proxies and diversity patterns in a wide variety of fauna and flora. Yet climate consists of many interacting variables. Species probably respond to the entire climate system as opposed to its individual facets. Here, we examine ecological and morphological traits of 12 633 individuals of two species of planktonic foraminifera with similar ecologies but contrasting evolutionary outcomes. Our results show that morphological and ecological changes are correlated to the interactions between multiple environmental factors. Models including interactions between climate variables explain at least twice as much variation in size, shape and abundance changes as models assuming that climate parameters operate independently. No dominant climatic driver can be identified: temperature alone explains remarkably little variation through our highly resolved temporal sequences, implying that a multivariate approach is required to understand evolutionary response to abiotic forcing. Our results caution against the use of a 'silver bullet' environmental parameter to represent global climate while studying evolutionary responses to abiotic change, and show that more comprehensive reconstruction of palaeobiological dynamics requires multiple biotic and abiotic dimensions.


Assuntos
Evolução Biológica , Mudança Climática , Foraminíferos/citologia , Foraminíferos/fisiologia , Traços de História de Vida , Animais , Temperatura Ambiente , Zooplâncton/citologia , Zooplâncton/fisiologia
8.
Sci Rep ; 8(1): 9560, 2018 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-29934603

RESUMO

Large benthic foraminifera (LBF) are marine calcifying protists that commonly harbor algae as symbionts. These organisms are major calcium carbonate producers and important contributors to primary production in the photic zones. Light is one of the main known factors limiting their distribution, and species of this group developed specific mechanisms that allow them to occupy different habitats across the light gradient. Operculina ammonoides (Gronovius, 1781) is a planispiral LBF that has two main shell morphotypes, thick involute and flat evolute. Earlier studies suggested morphologic changes with variation in water depth and presumably light. In this study, specimens of the two morphotypes were placed in the laboratory under artificial low light and near the sea floor at depths of 15 m, 30 m, and 45 m in the Gulf of Aqaba-Eilat for 23 days. Differences in growth and symbionts content were evaluated using weight, size, and chlorophyll a. Our results show that O. ammonoides exhibit morphological plasticity when constructing thinner chambers after relocation to low light conditions, and adding more weight per area after relocation to high light conditions. In addition, O. ammonoides exhibited chlorophyll content adaptation to a certain range of light conditions, and evolute specimens that were acclimatized to very low light did not survive relocation to a high light environment, possibly due to photo-oxidative stress.


Assuntos
Adaptação Fisiológica , Convolvulaceae/microbiologia , Foraminíferos/fisiologia , Simbiose , Clorofila/metabolismo , Convolvulaceae/metabolismo , Fósseis , Laboratórios , Luz , Temperatura Ambiente
9.
Sci Rep ; 8(1): 8189, 2018 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-29844498

RESUMO

Symbiont-bearing Larger Benthic Foraminifera (LBF) are ubiquitous components of shallow tropical and subtropical environments and contribute substantially to carbonaceous reef and shelf sediments. Climate change is dramatically affecting carbonate producing organisms and threatens the diversity and structural integrity of coral reef ecosystems. Recent invertebrate and vertebrate surveys have identified the Coral Triangle as the planet's richest center of marine life delineating the region as a top priority for conservation. We compiled and analyzed extensive occurrence records for 68 validly recognized species of LBF from the Indian and Pacific Ocean, established individual range maps and applied Minimum Convex Polygon (MCP) and Species Distribution Model (SDM) methodologies to create the first ocean-wide species richness maps. SDM output was further used for visualizing latitudinal and longitudinal diversity gradients. Our findings provide strong support for assigning the tropical Central Indo-Pacific as the world's species-richest marine region with the Central Philippines emerging as the bullseye of LBF diversity. Sea surface temperature and nutrient content were identified as the most influential environmental constraints exerting control over the distribution of LBF. Our findings contribute to the completion of worldwide research on tropical marine biodiversity patterns and the identification of targeting centers for conservation efforts.


Assuntos
Antozoários/fisiologia , Biodiversidade , Recifes de Corais , Foraminíferos/fisiologia , Animais , Carbonatos/metabolismo , Mudança Climática , Ecossistema , Oceano Índico , Modelos Biológicos , Oceano Pacífico , Simbiose , Clima Tropical
10.
Mar Environ Res ; 138: 36-45, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29680163

RESUMO

Coastal areas display natural large environmental variability such as frequent changes in salinity, pH, and carbonate chemistry. Anthropogenic impacts - especially ocean acidification - increase this variability, which may affect the living conditions of coastal species, particularly, calcifiers. We performed culture experiments on living benthic foraminifera to study the combined effects of lowered pH and salinity on the calcification abilities and survival of the coastal, calcitic species Ammonia sp. and Elphidium crispum. We found that in open ocean conditions (salinity ∼35) and lower pH than usual values for these species, the specimens displayed resistance to shell (test) dissolution for a longer time than in brackish conditions (salinity ∼5 to 20). However, the response was species specific as Ammonia sp. specimens survived longer than E. crispum specimens when placed in the same conditions of salinity and pH. Living, decalcified juveniles of Ammonia sp. were observed and we show that desalination is one cause for the decalcification. Finally, we highlight the ability of foraminifera to survive under Ωcalc < 1, and that high salinity and [Ca2+] as building blocks are crucial for the foraminiferal calcification process.


Assuntos
Adaptação Fisiológica , Foraminíferos/fisiologia , Água do Mar/química , Calcificação Fisiológica , Carbonato de Cálcio , Monitoramento Ambiental , Foraminíferos/química , Concentração de Íons de Hidrogênio , Salinidade
11.
PLoS One ; 12(11): e0188447, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29166653

RESUMO

We present paleo-water depth reconstructions for the Pefka E section deposited on the island of Rhodes (Greece) during the early Pleistocene. For these reconstructions, a transfer function (TF) using modern benthic foraminifera surface samples from the Adriatic and Western Mediterranean Seas has been developed. The TF model gives an overall predictive accuracy of ~50 m over a water depth range of ~1200 m. Two separate TF models for shallower and deeper water depth ranges indicate a good predictive accuracy of 9 m for shallower water depths (0-200 m) but far less accuracy of 130 m for deeper water depths (200-1200 m) due to uneven sampling along the water depth gradient. To test the robustness of the TF, we randomly selected modern samples to develop random TFs, showing that the model is robust for water depths between 20 and 850 m while greater water depths are underestimated. We applied the TF to the Pefka E fossil data set. The goodness-of-fit statistics showed that most fossil samples have a poor to extremely poor fit to water depth. We interpret this as a consequence of a lack of modern analogues for the fossil samples and removed all samples with extremely poor fit. To test the robustness and significance of the reconstructions, we compared them to reconstructions from an alternative TF model based on the modern analogue technique and applied the randomization TF test. We found our estimates to be robust and significant at the 95% confidence level, but we also observed that our estimates are strongly overprinted by orbital, precession-driven changes in paleo-productivity and corrected our estimates by filtering out the precession-related component. We compared our corrected record to reconstructions based on a modified plankton/benthos (P/B) ratio, excluding infaunal species, and to stable oxygen isotope data from the same section, as well as to paleo-water depth estimates for the Lindos Bay Formation of other sediment sections of Rhodes. These comparisons indicate that our orbital-corrected reconstructions are reasonable and reflect major tectonic movements of Rhodes during the early Pleistocene.


Assuntos
Ecossistema , Foraminíferos/fisiologia , Paleontologia , Fósseis , Geografia , Grécia , Mar Mediterrâneo , Modelos Teóricos , Especificidade da Espécie , Fatores de Tempo
12.
Nat Commun ; 8: 15441, 2017 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-28504274

RESUMO

The relationship between seawater temperature and the average Mg/Ca ratios in planktic foraminifera is well established, providing an essential tool for reconstructing past ocean temperatures. However, many species display alternating high and low Mg-bands within their shell walls that cannot be explained by temperature alone. Recent experiments demonstrate that intrashell Mg variability in Orbulina universa, which forms a spherical terminal shell, is paced by the diurnal light/dark cycle. Whether Mg-heterogeneity is also diurnally paced in species with more complex shell morphologies is unknown. Here we show that high Mg/Ca-calcite forms at night in cultured specimens of the multi-chambered species Neogloboquadrina dutertrei. Our results demonstrate that N. dutertrei adds a significant amount of calcite, and nearly all Mg-bands, after the final chamber forms. These results have implications for interpreting patterns of calcification in N. dutertrei and suggest that diurnal Mg-banding is an intrinsic component of biomineralization in planktic foraminifera.


Assuntos
Carbonato de Cálcio/química , Foraminíferos/fisiologia , Magnésio/química , Água do Mar , Calcificação Fisiológica , Oceanos e Mares , Temperatura Ambiente , Oligoelementos
13.
Sci Rep ; 7: 45227, 2017 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-28332634

RESUMO

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.


Assuntos
Foraminíferos/fisiologia , Aquecimento Global , Oceanos e Mares , Adaptação Fisiológica , Biomassa , Clorofila/metabolismo , Foraminíferos/metabolismo
14.
Microbiome ; 5(1): 38, 2017 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-28335814

RESUMO

BACKGROUND: Symbiosis is a phenomenon that allows organisms to colonise a wide range of environments and occupy a variety of ecological niches in marine environments. Large benthic foraminifera (LBF) are crucial marine calcifiers that rely on photo-endosymbionts for growth and calcification, yet the influence of environmental conditions in shaping their interactions with prokaryotic and eukaryotic associates is poorly known. RESULTS: Here, we used next-generation sequencing to identify eukaryotic photosynthesizing and prokaryotic microbes associated with the common LBF Amphistegina lobifera across a physio-chemical gradient on the Great Barrier Reef (GBR). We collected samples from three reef sites located in the inner-, mid- and outer-shelf regions of the northern section of the GBR. Results showed the consistent presence of Bacillaryophyta as the main eukaryotic taxa associated with A. lobifera across all reef sites analysed; however, the abundance and the diversity of prokaryotic organisms varied among reef sites. Inner-shelf specimens showed the highest diversity of prokaryote associates, with a total of 231 genotypes in their core microbiome. A total of 30 taxa were identified in the core microbiome across all reef sites. Within these taxa, Proteobacteria was the most abundant bacteria present. The presence of groups such as Actinobacteria was significantly correlated with inner-shelf populations, whereas the abundance of Bacteroidetes and Firmicutes was associated with A. lobifera collected from mid- and outer-shelf reef sites. CONCLUSIONS: We found that benthic foraminifera form stable and persistent symbiosis with eukaryotic partners, but flexible and site-specific associations with prokaryotic microbes that likely influence the ecological success of these crucial calcifying organisms on the GBR.


Assuntos
Actinobacteria/isolamento & purificação , Bacteroidetes/isolamento & purificação , Firmicutes/isolamento & purificação , Foraminíferos/fisiologia , Microbiota/fisiologia , Proteobactérias/isolamento & purificação , Actinobacteria/classificação , Actinobacteria/genética , Bacteroidetes/classificação , Bacteroidetes/genética , Sequência de Bases , Recifes de Corais , Firmicutes/classificação , Firmicutes/genética , Foraminíferos/genética , Sequenciamento de Nucleotídeos em Larga Escala , Microbiota/genética , Proteobactérias/classificação , Proteobactérias/genética , RNA de Cloroplastos/genética , RNA Ribossômico 18S/genética , Análise de Sequência de DNA , Simbiose
15.
ISME J ; 11(2): 453-462, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27801906

RESUMO

Light underpins the health and function of coral reef ecosystems, where symbiotic partnerships with photosynthetic algae constitute the life support system of the reef. Decades of research have given us detailed knowledge of the photoprotective capacity of phototrophic organisms, yet little is known about the role of the host in providing photoprotection in symbiotic systems. Here we show that the intracellular symbionts within the large photosymbiotic foraminifera Marginopora vertebralis exhibit phototactic behaviour, and that the phototactic movement of the symbionts is accomplished by the host, through rapid actin-mediated relocation of the symbionts deeper into the cavities within the calcium carbonate test. Using a photosynthetic inhibitor, we identified that the infochemical signalling for host regulation is photosynthetically derived, highlighting the presence of an intimate communication between the symbiont and the host. Our results emphasise the central importance of the host in photosymbiotic photoprotection via a new mechanism in foraminifera that can serve as a platform for exploring host-symbiont communication in other photosymbiotic organisms.


Assuntos
Antozoários/fisiologia , Foraminíferos/fisiologia , Simbiose , Animais , Recifes de Corais , Ecossistema , Fotossíntese
16.
PLoS One ; 11(11): e0165844, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27812157

RESUMO

Large benthic foraminifera are unicellular calcifying reef organisms that can form symbiotic relationships with a range of different microalgae. However, the cellular functions, such as symbiosis and calcification, and other aspects of cellular physiology in large benthic foraminifera are not fully understood. Amphisorus kudakajimensis was used as a model to determine the detailed cellular characteristics of large benthic foraminifera. We used calcein acetoxymethyl ester (calcein AM) as a fluorescent indicator for live confocal imaging. We demonstrated that calcein AM is a useful fluorescent indicator to stain the fine network of reticulopodia and the cytoplasm in living A. kudakajimensis. We showed that at least two types of reticulopodia exist in A. kudakajimensis: the straight bundle of reticulopodia that spreads from the aperture and the fine reticulopodia along the surface of the aperture and chamber walls. The cytoplasm in outer chambers was highly branched and contained a few dinoflagellates. In contrast, the inner chamberlets contained condensed cytoplasm and many dinoflagellates, suggesting that the cytoplasm of A. kudakajimensis performs different functions based on its location within the large test. Our confocal detailed image analysis provides real-time cellular morphology and cell physiology of living foraminifera.


Assuntos
Fluoresceínas/metabolismo , Foraminíferos/citologia , Foraminíferos/metabolismo , Imagem Óptica , Simbiose , Citoplasma/metabolismo , Foraminíferos/fisiologia , Coloração e Rotulagem
17.
PLoS One ; 11(11): e0165522, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27851751

RESUMO

Global diversity patterns are thought to result from a combination of environmental and historical factors. This study tests the set of ecological and evolutionary hypotheses proposed to explain the global variation in present-day coretop diversity in the macroperforate planktonic foraminifera, a clade with an exceptional fossil record. Within this group, marine surface sediment assemblages are thought to represent an accurate, although centennial to millennial time-averaged, representation of recent diversity patterns. Environmental variables chosen to capture ocean temperature, structure, productivity and seasonality were used to model a range of diversity measures across the world's oceans. Spatial autoregressive models showed that the same broad suite of environmental variables were important in shaping each of the four largely independent diversity measures (rarefied species richness, Simpson's evenness, functional richness and mean evolutionary age). Sea-surface temperature explains the largest portion of diversity in all four diversity measures, but not in the way predicted by the metabolic theory of ecology. Vertical structure could be linked to increased diversity through the strength of stratification, but not through the depth of the mixed layer. There is limited evidence that seasonal turnover explains diversity patterns. There is evidence for functional redundancy in the low-latitude sites. The evolutionary mechanism of deep-time stability finds mixed support whilst there is relatively little evidence for an out-of-the-tropics model. These results suggest the diversity patterns of planktonic foraminifera cannot be explained by any one environmental variable or proposed mechanism, but instead reflect multiple processes acting in concert.


Assuntos
Biodiversidade , Foraminíferos/fisiologia , Sedimentos Geológicos/microbiologia , Plâncton/fisiologia , Internacionalidade , Funções Verossimilhança , Oceanos e Mares , Filogenia , Característica Quantitativa Herdável , Especificidade da Espécie , Temperatura Ambiente
18.
Sci Rep ; 6: 30930, 2016 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-27502580

RESUMO

Bleaching, the loss of algal symbionts, occurs in marine photosymbiotic organisms at water temperatures minimally exceeding average summer SST (sea surface temperatures). Pre-adaptation allows organisms to persist under warmer conditions, providing the tolerance can be carried to new habitats. Here we provide evidence for the existence of such adaptation in the benthic foraminifera Pararotalia calcariformata. This species occurs at a thermally polluted site in the Mediterranean, where water temperatures reach a maxima daily average of 36 °C during the summer. To test whether this occurrence represents a widespread adaptation, we conducted manipulative experiments exposing this species from an unpolluted site to elevated temperatures (20-42 °C). It was kept in co-culture with the more thermally sensitive foraminifera Amphistegina lobifera in two experiments (20-36 °C). Reduced photosynthetic activity in A. lobifera occurred at 32 °C whereas photochemical stress in P. calcariformata was first observed during exposure to 36 °C. Pararotalia calcariformata survived all treatment conditions and grew under 36 °C. The photosymbiosis in P. calcariformata is unusually thermally tolerant. These observations imply that marine eukaryote-eukaryote photosymbiosis can respond to elevated temperatures by drawing on a pool of naturally occurring pre-adaptations. It also provides a perspective on the massive occurrence of symbiont-bearing foraminifera in the early Cenozoic hothouse climate.


Assuntos
Adaptação Fisiológica/fisiologia , Foraminíferos/fisiologia , Temperatura Alta , Fotoquímica , Simbiose/fisiologia , Foraminíferos/efeitos da radiação , Região do Mediterrâneo , Água do Mar , Simbiose/efeitos da radiação
19.
Nat Commun ; 7: 11970, 2016 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-27311937

RESUMO

Understanding the interaction between climate and biotic evolution is crucial for deciphering the sensitivity of life. An enigmatic mass extinction occurred in the deep oceans during the Mid Pleistocene, with a loss of over 100 species (20%) of sea floor calcareous foraminifera. An evolutionarily conservative group, benthic foraminifera often comprise >50% of eukaryote biomass on the deep-ocean floor. Here we test extinction hypotheses (temperature, corrosiveness and productivity) in the Tasman Sea, using geochemistry and micropalaeontology, and find evidence from several globally distributed sites that the extinction was caused by a change in phytoplankton food source. Coccolithophore evolution may have enhanced the seasonal 'bloom' nature of primary productivity and fundamentally shifted it towards a more intra-annually variable state at ∼0.8 Ma. Our results highlight intra-annual variability as a potential new consideration for Mid Pleistocene global biogeochemical climate models, and imply that deep-sea biota may be sensitive to future changes in productivity.


Assuntos
Mudança Climática/história , Extinção Biológica , Foraminíferos/fisiologia , Paleontologia/métodos , Fitoplâncton/fisiologia , Biodiversidade , Biomassa , História Antiga , Oceano Pacífico , Temperatura Ambiente
20.
Mar Environ Res ; 117: 32-43, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27074196

RESUMO

Over the last centuries, coastal areas have experienced dramatic degradations of their environmental quality, which has led to a huge reduction of marine biodiversity. The objective of the present study was to use geochemical parameters and benthic fossil foraminifera to assess environmental changes that have occurred over the last 200 years in a harbour area (Boulogne-sur-Mer, Northern France) heavily modified by human activities. A multidisciplinary approach including major and trace metals, grain-size, total organic carbon and benthic fossil foraminifera, has been performed on a 33-cm long core. The dating was carried out using the activity of (210)Pb and (137)Cs. Embayment of the area and increase of trace metals concentrations induced a shift in benthic communities. Human activities modified a sandy nearshore bank, colonized by typical marine foraminiferal species, such as Cribroelphiudium excavatum, into a sheltered environment, dominated by brackish end-members, such as Haynesina germanica. Along the sedimentary record, the interaction between meiofaunal and geochemical elements made it possible to distinguish between a pre-impacted period and an industrial period. The upper part of the core reflects better ecological conditions, indicating an environmental recovery. Our results provide baselines for future environmental bio-monitoring in the area.


Assuntos
Monitoramento Ambiental/métodos , Foraminíferos/fisiologia , Poluição da Água/estatística & dados numéricos , Biodiversidade , França , Sedimentos Geológicos , Água do Mar , Qualidade da Água
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