Loading...
17 results
Search Results
Now showing 1 - 10 of 17
- Exploring the response of a key Mediterranean gorgonian to heat stress across biological and spatial scalesPublication . Gómez-Gras, D.; Bensoussan, N.; Ledoux, J. B.; López-Sendino, P.; Cerrano, C.; Ferretti, E.; Kipson, S.; Bakran-Petricioli, T.; A, Serrão; Paulo, D.; Coelho, Márcio; Pearson, Gareth; Boavida, J.; Montero-Serra, I.; Pagès-Escolà, M.; Medrano, A.; López-Sanz, A.; Milanese, M.; Linares, C.; Garrabou, J.Understanding the factors and processes that shape intra-specific sensitivity to heat stress is fundamental to better predicting the vulnerability of benthic species to climate change. Here, we investigate the response of a habitat-forming Mediterranean octocoral, the red gorgonian Paramuricea clavata (Risso, 1826) to thermal stress at multiple biological and geographical scales. Samples from eleven P. clavata populations inhabiting four localities separated by hundreds to more than 1500 km of coast and with contrasting thermal histories were exposed to a critical temperature threshold (25 degrees C) in a common garden experiment in aquaria. Ten of the 11 populations lacked thermotolerance to the experimental conditions provided (25 days at 25 degrees C), with 100% or almost 100% colony mortality by the end of the experiment. Furthermore, we found no significant association between local average thermal regimes nor recent thermal history (i.e., local water temperatures in the 3 months prior to the experiment) and population thermotolerance. Overall, our results suggest that local adaptation and/or acclimation to warmer conditions have a limited role in the response of P. clavata to thermal stress. The study also confirms the sensitivity of this species to warm temperatures across its distributional range and questions its adaptive capacity under ocean warming conditions. However, important inter-individual variation in thermotolerance was found within populations, particularly those exposed to the most severe prior marine heatwaves. These observations suggest that P. clavata could harbor adaptive potential to future warming acting on standing genetic variation (i.e., divergent selection) and/or environmentally-induced phenotypic variation (i.e., intra- and/or intergenerational plasticity).
- Genetic diversity increases with depth in red gorgonian populations of the Mediterranean Sea and the Atlantic OceanPublication . Pilczynska, Joanna; Cocito, Silvia; Boavida, Joana; Serrao, Ester; Assis, J.; Fragkopoulou, Eliza; Queiroga, HenriqueIn the ocean, the variability of environmental conditions found along depth gradients exposes populations to contrasting levels of perturbation, which can be reflected in the overall patterns of species genetic diversity. At shallow sites, resource availability may structure large, persistent and well-connected populations with higher levels of diversity. In contrast, the more extreme conditions, such as thermal stress during heat waves, can lead to population bottlenecks and genetic erosion, inverting the natural expectation. Here we examine how genetic diversity varies along depth for a long-lived, important ecosystem-structuring species, the red gorgonian, Paramuricea clavata.
- Genetic structure of amphi-Atlantic Laminaria digitata (Laminariales, Phaeophyceae) reveals a unique range-edge gene pool and suggests post-glacial colonization of the NW AtlanticPublication . Neiva, J.; Serrao, Ester; Paulino, Cristina; Gouveia, Licínia; Want, Andrew; Tamigneaux, Éric; Ballenghien, Marion; Mauger, Stéphane; Fouqueau, Louise; Engel-Gautier, Carolyn; Destombe, Christophe; Valero, MyriamIn the North-east (NE) Atlantic, most intertidal fucoids and warm-temperate kelps show unique low-latitude gene pools matching long-term climatic refugia. For cold-temperate kelps data are scarcer despite their unique cultural, ecological and economic significance. Here we test whether the amphi-Atlantic range of Laminaria digitata is derived from past glacial survival (and vicariance) in both NE and North-west (NW) Atlantic refugia (as suggested by niche modelling), or post-glacial (re)colonization (as suggested by low mtDNA divergence). We screened 14 populations from across the species range for 12 microsatellite loci to identify and map major gene pools and refugia. We assessed if NW Atlantic survival was supported by unique endemic variation, and if genetic diversity and structure were, as predicted from larger hindcasted glacial ranges, higher in the NE Atlantic. Microsatellite data subdivided L. digitata into three main genetic groups matching Brittany, northern Europe and the NW Atlantic, with finer-scale sub-structuring within European clusters. The relatively diverse NE Atlantic lineages probably survived the Last Glacial Maximum along unglaciated periglacial shorelines of the Armorican and Celtic Seas (Brittany cluster) and Ireland (northern European cluster), and remain well differentiated despite their relative proximity. The unique Brittany gene pool, at the contemporary European rear edge, is projected to disappear in the near future under high greenhouse gas emission scenarios. Low allelic diversity and low endemism in the NW Atlantic are consistent with recent post-glacial colonization from Europe, challenging the long-standing hypothesis of in situ glacial survival. Confusion with Hedophyllum nigripes may have led to underestimation of regional diversity of L. digitata, but also to overestimation of its presence along putative trans-Atlantic migration routes. Partial incongruence between modelling and genetic-based biogeographic inferences highlights the benefits of comparing both approaches to understand how shifting climatic conditions affect marine species distributions and explain large-scale patterns of spatial genetic structure.
- Global impacts of projected climate changes on the extent and aboveground biomass of mangrove forestsPublication . Gouvêa, Lidiane; A, Serrão; Cavanaugh, Kyle; Gurgel, Carlos F. D.; Horta, Paulo A.; Assis, JorgeAim: Over the past 50 years, anthropogenic activities have led to the disappearance of approximately one-third of the world's mangrove forests and their associated ecosystem services. The synergetic combined effect of projected climate change is likely to further impact mangroves in the years to come, whether by range expansions associated with warming at higher latitudes or large-scale diebacks linked to severe droughts. We provide an estimate of future changes in the extent and aboveground biomass (AGB) of mangrove forests at global scales by considering contrasting Representative Concentration Pathway scenarios (decade 2090-2100 under RCP 2.6 in line with the Paris Agreement expectations, and RCP 8.5 of higher emissions). Location: Global. Methods: Boosted regression trees fitted occurrence and AGB of mangroves against high-resolution biologically meaningful data on air temperature, precipitation, wave energy, slope and distance to river Deltas. Results: On the global scale, models produced for present-day conditions retrieved high accuracy scores and estimated a total area of 12,780,356 ha and overall biomass of 2.29 Pg, in line with previous estimates. Model projections showed poleward shifts along temperate regions, which translated into comparable gains in total area, regardless of the RCP scenario (area change RCP 2.6: 17.29%; RCP 8.5: 15.77%). However, biomass changes were dependent on the emission scenario considered, remaining stable or even increasing under RCP 2.6, or undergoing severe losses across tropical regions under RCP 8.5 (overall biomass change RCP 2.6: 12.97%; RCP 8.5: -11.51%). Such losses were particularly aggravated in countries located in the Tropical Atlantic and Eastern Pacific, and the Western and Eastern Indo-Pacific regions (regions with losses above similar to 20% in overall biomass). Conclusions: Our global estimates highlight the potential effect of future climate changes on mangrove forests and how broad compliance with the Paris Agreement may counteract severe trajectories of loss. The projections made, also provided at the country level, serve as new baselines to evaluate changes in mangrove carbon sequestration and ecosystem services, strongly supporting policy-making and management directives, as well as to guide restoration actions considering potential future changes in niche availability.
- Climate-induced range shifts shaped the present and threaten the future genetic variability of a marine brown alga in the Northwest PacificPublication . Song, Xiao-Han; Assis, Jorge; Jie Zhang, Jie; Gao, Xu; Cho, Han-Gil; Duan, De-Lin; Serrao, Ester; Hu, Zi-MinGlaciation-induced environmental changes during the last glacial maximum (LGM) have strongly influenced species' distributions and genetic diversity patterns in the northern high latitudes. However, these effects have seldom been assessed on sessile species in the Northwest Pacific. Herein, we chose the brown alga Sargassum thunbergii to test this hypothesis, by comparing present population genetic variability with inferred geographical range shifts from the LGM to the present, estimated with species distribution modelling (SDM). Projections for contrasting scenarios of future climate change were also developed to anticipate genetic diversity losses at regional scales. Results showed that S. thunbergii harbours strikingly rich genetic diversity and multiple divergent lineages in the centre-northern range of its distribution, in contrast with a poorer genetically distinct lineage in the southern range. SDM hindcasted refugial persistence in the southern range during the LGM as well as post-LGM expansion of 18 degrees of latitude northward. Approximate Bayesian computation (ABC) analysis further suggested that the multiple divergent lineages in the centre-northern range limit stem from post-LGM colonization from the southern survived lineage. This suggests divergence due to demographic bottlenecks during range expansion and massive genetic diversity loss during post-LGM contraction in the south. The projected future range of S. thunbergii highlights the threat to unique gene pools that might be lost under global changes.
- Ocean currents shape the genetic structure of a kelp in southwestern AfricaPublication . Assis, Jorge; Neiva, J.; Bolton, John J.; Rothman, Mark D.; Gouveia, Licínia; Paulino, Cristina; Mohdnasir, Hasliza; Anderson, Robert J.; Reddy, Maggie M.; Kandjengo, Lineekela; Kreiner, Anja; Pearson, Gareth; Serrao, EsterAim Drivers of extant population genetic structure include past climate-driven range shifts and vicariant events, as well as gene flow mediated by dispersal and habitat continuity. Their integration as alternative or complementary drivers is often missing or incomplete, potentially overlooking relevant processes and time scales. Here we ask whether it is the imprint of past range shifts or habitat connectivity driven by oceanographic transport that best explain genetic structure in a poorly understood model, a forest-forming African kelp. Location Southwestern coast of Africa (Benguela current region). Taxon Laminaria pallida. Methods We estimated genetic variability along the species distributional range using 14 microsatellite markers. This genetic variability was compared to estimates of past range shifts derived from species distribution modelling for the Last Glacial Maximum (LGM), the mid-Holocene (MH) and the present, and estimates of habitat connectivity derived from oceanographic biophysical modelling. Results The species is structured in two clusters, a southern cluster with much richer (allelic richness A: 10.40 +/- 0.33) and unique (private alleles PA: 56.69 +/- 4.05) genetic diversity, and a northern cluster (A: 4.75 +/- 0.17; PA: 6.70 +/- 1.45). These clusters matched well-known biogeographical regions and their transition coincided with a dispersal barrier formed by upwelled offshore transport. No major range shifts or vicariant events were hindcasted along the present range, suggesting population stability from the LGM to the present. Main conclusions Habitat connectivity, rather than past range shifts, explains the extant population structure. Future environmental requirements of the species along the Benguela upwelling system are projected to persist or even intensify, likely preserving the observed genetic patterns for the years to come. Yet, the differentiation and endemicity between clusters, and the isolation structured by the regional oceanography, implies high conservation value for genetic biodiversity, and even more if considering the ecological, social and economic services provided by kelp forests.
- Bottom trawling threatens future climate refugia of rhodoliths globallyPublication . Fragkopoulou, Eliza; Serrao, Ester; Horta, Paulo A.; Koerich, Gabrielle; Assis, J.Climate driven range shifts are driving the redistribution of marine species and threatening the functioning and stability of marine ecosystems. For species that are the structural basis of marine ecosystems, such effects can be magnified into drastic loss of ecosystem functioning and resilience. Rhodoliths are unattached calcareous red algae that provide key complex three-dimensional habitats for highly diverse biological communities. These globally distributed biodiversity hotspots are increasingly threatened by ongoing environmental changes, mainly ocean acidification and warming, with wide negative impacts anticipated in the years to come. These are superimposed upon major local stressors caused by direct destructive impacts, such as bottom trawling, which act synergistically in the deterioration of the rhodolith ecosystem health and function. Anticipating the potential impacts of future environmental changes on the rhodolith biome may inform timely mitigation strategies integrating local effects of bottom trawling over vulnerable areas at global scales. This study aimed to identify future climate refugia, as regions where persistence is predicted under contrasting climate scenarios, and to analyze their trawling threat levels. This was approached by developing species distribution models with ecologically relevant environmental predictors, combined with the development of a global bottom trawling intensity index to identify heavily fished regions overlaying rhodoliths. Our results revealed the importance of light, thermal stress and pH driving the global distribution of rhodoliths. Future projections showed poleward expansions and contractions of suitable habitats at lower latitudes, structuring cryptic depth refugia, particularly evident under the more severe warming scenario RCP 8.5. Our results suggest that if management and conservation measures are not taken, bottom trawling may directly threaten the persistence of key rhodolith refugia. Since rhodoliths have slow growth rates, high sensitivity and ecological importance, understanding how their current and future distribution might be susceptible to bottom trawling pressure, may contribute to determine the fate of both the species and their associated communities.
- Expressed sequence tags from heat-shocked seagrass Zostera noltii (Hornemann) from its southern distribution rangePublication . Massa, S. I.; Pearson, G. A.; Aires, Tânia; Kube, M.; Olsen, J. L.; Reinhardt, Richard; Serrão, Ester; ARNAUD-HAOND, SophiePredicted global climate change threatens the distributional ranges of species worldwide. We identified genes expressed in the intertidal seagrass Zostera noltii during recovery from a simulated low tide heat-shock exposure. Five Expressed Sequence Tag (EST) libraries were compared, corresponding to four recovery times following sub-lethal temperature stress, and a non-stressed control. We sequenced and analyzed 7009 sequence reads from 30 min, 2 h, 4 h and 24 h after the beginning of the heat-shock (AHS), and 1585 from the control library, for a total of 8594 sequence reads. Among 51 Tentative UniGenes (TUGs) exhibiting significantly different expression between libraries, 19 (37.3%) were identified as ‘molecular chaperones’ and were over-expressed following heat-shock, while 12 (23.5%) were ‘photosynthesis TUGs’ generally under-expressed in heat-shocked plants. A time course analysis of expression showed a rapid increase in expression of the molecular chaperone class, most of which were heat-shock proteins; which increased from 2 sequence reads in the control library to almost 230 in the 30 min AHS library, followed by a slow decrease during further recovery. In contrast, ‘photosynthesis TUGs’ were under-expressed 30 min AHS compared with the control library, and declined progressively with recovery time in the stress libraries, with a total of 29 sequence reads 24 h AHS, compared with 125 in the control. A total of 4734 TUGs were screened for EST-Single Sequence Repeats (EST-SSRs) and 86 microsatellites were identified.► Response to heat stress is very fast but gene expression returns to normal after 24 h. ► Photosynthesis-related genes were under-expressed after heat-shock. ► Heat-shock caused a quick rise in heat shock proteins and molecular chaperone expression.
- Phenotypic plasticity in sargassum forests may not counteract projected biomass losses along a broad latitudinal gradientPublication . Gouvêa, Lidiane; Horta, Paulo A.; Fragkopoulou, Eliza; Gurgel, Carlos F. D.; Peres, Leticia M. C.; Bastos, Eduardo; Ramlov, Fernanda; Burle, Giulia; Koerich, Gabrielle; Martins, Cintia D. L.; Serrao, Ester; Assis, JorgePhenotypic plasticity and local adaptation can adjust individual responses to environmental changes across species' ranges. Studies addressing the implications of such traits have been underrepresented in the marine environment. Sargassum cymosum represents an ideal model to test phenotypic plasticity, as populations along the southwestern Atlantic Ocean display a sharp decrease in abundance toward distributional range limits. We (1) characterized the macroecological environment of S. cymosum across a latitudinal gradient, (2) evaluated potential differences in ecophysiological adjustments (biomass, photosynthetic pigments, phenolic compounds, total soluble sugars and proteins, and carbon-nitrogen-CN-content), and (3) tested for differences in thermal tolerance based on time series analyses produced from the present to contrasting representative concentration pathways scenarios (RCP) of future climate changes. Our results showed distinct macroecological environments, corresponding to tropical and warm temperate conditions, driving biomass and ecophysiological adjustments of S. cymosum. Populations from the two environments displayed contrasting thermal tolerances, with tropical individuals better coping with thermal stress when compared to more temperate ones (lethal temperatures of 33 degrees C vs. 30 degrees C); yet both populations lose biomass in response to increasing thermal stress while increasing secondary metabolites (for example, carotenoids and phenolic compounds) and decrease chlorophyll's content, Fv/Fm, total soluble sugars concentration and CN ratio, owing to oxidative stress. Despite evidence for phenotypic plasticity, significant future losses might occur in both tropical and warm temperate populations, particularly under the no mitigation RCP scenario, also known as the business as usual (that is, 8.5). In this context, broad compliance with the Paris Agreement might counteract projected impacts of climate change, safeguarding Sargassum forests in the years to come.
- Major expansion of marine forests in a warmer ArcticPublication . Assis, Jorge; Serrao, Ester; Duarte, Carlos M.; Fragkopoulou, Eliza; Krause-Jensen, DorteAccelerating warming and associated loss of sea ice are expected to promote the expansion of coastal marine forests (macrophytes) along the massive Arctic coastlines. Yet, this region has received much less attention compared to other global oceans. The available future projections of Arctic macrophytes are still limited to few species and regions, and mostly focused at lower latitude ranges, thus precluding well-informed IPCC impact assessments, conservation and management. Here we aim to quantify potential distributional changes of Arctic intertidal and subtidal brown macroalgae and eelgrass by the year 2100, relative to present. We estimate habitat suitability by means of species distribution modeling, considering changes in seawater temperature, salinity, nutrients and sea ice cover under two greenhouse gas emission scenarios, one consistent with the Paris Agreement (RCP 2.6) and the other representing limited mitigation strategies (RCP 8.5). As data on substrate conditions do not exist, the models were restricted to the depth range supporting Arctic macrophytes (down to 5 m for eelgrass and 30 m for brown macroalgae). Models projected major expansions of Arctic macrophytes between 69,940 and 123,360 km2, depending on the climate scenario, with polar distribution limits shifting northwards by up to 1.5 latitude degrees at 21.81 km per decade. Such expansions in response to changing climate will likely elicit major changes in biodiversity and ecosystem functions in the future Arctic. Expansions are, however, less intense than those already realized over the past century, indicating an overall slowing down despite accelerated warming as habitats become increasingly occupied..