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- Evidence for rangewide panmixia despite multiple barriers to dispersal in a marine musselPublication . Lourenço, Carla R.; Nicastro, Katy; McQuaid, Christopher D.; Chefaoui, Rosa; Assis, J.; Taleb, Mohammed Z.; Zardi, Gerardo I.Oceanographic features shape the distributional and genetic patterns of marine species by interrupting or promoting connections among populations. Although general patterns commonly arise, distributional ranges and genetic structure are species-specific and do not always comply with the expected trends. By applying a multimarker genetic approach combined with Lagrangian particle simulations (LPS) we tested the hypothesis that oceanographic features along northeastern Atlantic and Mediterranean shores influence dispersal potential and genetic structure of the intertidal mussel Perna perna. Additionally, by performing environmental niche modelling we assessed the potential and realized niche of P. perna along its entire native distributional range and the environmental factors that best explain its realized distribution. Perna perna showed evidence of panmixia across > 4,000 km despite several oceanographic breaking points detected by LPS. This is probably the result of a combination of life history traits, continuous habitat availability and stepping-stone dynamics. Moreover, the niche modelling framework depicted minimum sea surface temperatures (SST) as the major factor shaping P. perna distributional range limits along its native areas. Forthcoming warming SST is expected to further change these limits and allow the species to expand its range polewards though this may be accompanied by retreat from warmer areas.
- Latitudinal incidence of phototrophic shell-degrading endoliths and their effects on mussel bed microclimatesPublication . Lourenço, Carla R.; R Nicastro, Katy; McQuaid, Christopher D.; Sabour, Brahim; Zardi, Gerardo I.Aggregations of organisms commonly benefit their members by mitigating the effects of predators and environmental stresses. Mussel aggregations also form important intertidal matrices that support associated infaunal communities, the structures of which are largely shaped by the conditions within the interstitial spaces. Intertidal mussels are frequently parasitized by phototrophic endoliths that infest the shell and have thermoregulatory effects on both solitary and aggregated mussels by changing shell albedo. A large-scale sampling was carried out May June 2016 along Portuguese and Moroccan shores to investigate a latitudinal gradient of endolithic infestation of the intertidal mussel Mytilus galloprovincialis. Endolithic infestation increased towards lower latitudes most likely as a response of greater light availability. Additionally, artificial beds of either 100% non-infested or infested biomimetic mussels were used to test whether infestation alters the temperature and humidity of the interstitial spaces within beds, and if mussels surrounded by infested mussels experience lower body temperatures than those surrounded by non-infested ones. Conditions within beds of infested mussels were significantly cooler and more humid than in non-infested beds and individuals in the centre of infested mussel beds experienced significantly lower body temperatures. Under a scenario of warming climate, endolithic infestation of mussel beds might thus represent an ecological advantage not only for M. galloprovincialis as a species but also for the associated communities.
- Upwelling areas as climate change refugia for the distribution and genetic diversity of a marine macroalgaPublication . Lourenço, Carla R.; Zardi, Gerardo I.; McQuaid, Christopher D.; Serrão, Ester; Pearson, Gareth; Jacinto, Rita; Nicastro, Katy RAimGlobal climate change has profound and diverse effects on biological diversity. Identifying present-day climate refugia is an increasingly recognized strategy for the management of biodiversity loss. Such refugia are potential safe havens that enhance environmental diversity by buffering the effects of large scale change, facilitating species persistence at regional scales and conserving unique genetic diversity. Although their ecological effects are well studied, the potential of upwelling centres to act as refugia in a scenario of climate warming remains largely unexplored. Here, we investigate whether upwelled waters act as refugia in a region heavily affected by recent climatic changes.LocationShores of south-western Iberia and north-western Africa.MethodsWe compared changes in distribution of the canopy-forming macroalga Fucus guiryi with sea surface temperature patterns in five upwelling areas and adjacent warmer regions. Population diversity and structure was inferred from genotypic analyses using nine microsatellite loci.ResultsFucus guiryi has disappeared from large expanses of non-upwelling shores, currently persisting in areas characterized by strong upwelling and reduced or non-significant rates of warming. Populations of F. guiryi were more abundant towards upwelling centres. Furthermore, the genetic characterization of populations revealed distinct genetic groups associated with each upwelling system.Main conclusionsWithin a large region of predominantly changing climate, we highlight the fundamental importance of upwelling areas as favourable, comparatively stable climates where F. guiryi has retreated and persists, preserving unique portions of the species' genetic pool.