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Rethinking climate change vulnerability: Drivers patterns of thermal tolerance adaptation in the ocean.

Periodic Reporting for period 1 - DPaTh-To-Adapt (Rethinking climate change vulnerability: Drivers patterns of thermal tolerance adaptation in the ocean.)

Reporting period: 2016-03-01 to 2018-02-28

Ocean warming is driving large-scale changes to coastal ecosystems worldwide. Nevertheless, the distribution and magnitude of climate impacts is spatially variable. Not all locations are affected equally by warming and within any given biological community, species may respond differently to ongoing changes to the local climate regime. As such, it remains a pressing scientific objective to understand and predict how the ecological impacts and opportunities presented by warming will manifest both between and within local biological communities. Until now, global projections of the biological impacts of climate change have primarily considered that thermal niches remain constant across a species range, overlooking important variation in adaptive capacity among populations, with major implications for predicting warming vulnerability. Vulnerability of an organism to warming is a function of exposure (i.e. rate of warming) and inherent sensitivity to increasing temperatures. Sensitivity to warming in turn, is characterized by the proximity between an organism’s upper thermal limits and the maximum local environmental temperatures that it experiences. As such, warming sensitivity and vulnerability are dynamic between species, space and time, as they integrate intrinsic differences in the thermal niche between species and extrinsic differences in climatology between locations.

Quantifying the variability in local and regional warming vulnerability has important applications for the stewardship of coastal ecosystems. Local to regional scales are those at which governance typically occurs and are arguably the spatial scales of most interest to local users and stakeholders. This research facilitates ecosystem-based management by identifying potentially resistant locations (e.g. climate refugia) and populations (e.g. those pre-selected for warming tolerance), and vulnerable situations where reducing other pressures on biodiversity should be prioritized.

The overarching questions addressed by this project were 1) How do patterns in thermal tolerance breadth and thermal safety margins vary throughout species’ geographical ranges? And 2) What are the environmental drivers, biotic traits and evolutionary factors that determine an organisms thermal tolerance? Through identifying the nature of thermal tolerance patterns and identifying some of the mechanisms influencing these patterns, this research aims to increase the accuracy and resolution of predictions of the sensitivity of marine biota to climate change.
Specific studies from DPath-to-Adapt include:

1) Trans-Mediterranean study of thermal tolerance of marine macrophytes
This study identified similarities and differences in the optimal and upper thermal limits between species AND between populations of the same species, in accordance with different local climatic regimes across the Mediterranean study sites (Catalunya, Mallorca, Crete, Cyprus). Of particular note, the seagrass Posidonia oceanica was found to be the most vulnerable species to rising temperatures. However, themally resistant populations of P. oceanica were found in Cyprus, where summer temperatures already exceed the upper thermal limit for western Mediterranean populations, providing some hope for adaptation and survival of thermally resilient genotypes.

2) Leading edge of change: thermal tolerance breadth of polar and sub-polar seaweed populations
This study aimed to empirically test whether thermal tolerance breadth of key species of the Arctic coastal zone reflected patterns of local climate variability or the species' global thermal distribution. Populations of Fucus vesiculosus and Ascophyllum nodosum were collected from western and southwest Greenland and grown under ten temperature treatments ranging from 5 – 30 degrees, reflecting the broad range of conditions experienced in their distribution under current and future climates regimes. Physiological results from the experiments demonstrated remarkably broad thermal tolerance of these species at Arctic and sub-Arctic latitudes, signaling they will potentially benefit from the rapid warming in the region.

3) The contribution of local adaptation to the vulnerability of marine biota to warming
This study investigated the warming vulnerability for coastal marine communities across the globe, capturing the full spectrum of local physiological adaptability that may exist among species within a community. We contrasted spatial patterns of warming vulnerability predicted for locally-adapted populations to those based on populations of species with conserved thermal niches. We then upscale these patterns to the community level, using a “Community Vulnerability Index” which combines locally-adapted and conserved-niche models to generate a comparative index of warming vulnerability for coastal marine ecosystems. The CVI demonstrated high spatial variability in warming vulnerability within many coastal marine communities. The CVI identified several global hot-spots and safe-spots of climate change vulnerability in shallow ocean systems and highlighted many regions where populations with locally-adapted and conserved thermal niches display starkly different climate change vulnerabilities.

5) Integrating local adaptation into the ecology of climate change vulnerability
This study reviews how warming vulnerability can vary across a species range and in response to environmental variability and integrate local adaptation into current ecological theory about species vulnerability to warming. We propose a model of climate change vulnerability for marine organisms that integrates the full spectrum of species responses to warming from 'perfect' local adaptation to niche conservatism. We identify a wedge of potential thermal safety margins that occur across species' thermal range and the environmental and biotic factors that contribute to an organisms position within the wedge. We highlight how current ecological theory can be modified to incorporate patterns of local adaptation and highlight research priorities for the field.
During the MSCA I have been actively engaged in public dissemination of my research, which has been picked up by 44 news outlets, blogs, tweets, Facebook pages. A popular article I wrote was read over 40,000 times in six continents. Since 2016 I have supervised two Masters students and 1 Erasmus student and am participating in five international research working groups, focussing on questions relating to the resilience of marine ecosystems to global change. Within the past two years I have been awarded four competitive research grants as part of international research teams, totalling over 357,000 € in funding. Moreover, the MSCA has opened doorways for further employment. In 2017 I was awarded a Juan de la Cierva postdoctoral fellowship by the Spanish Government to continue ongoing research at IMEDEA following the MSCA.
Arctic Fjord_experimental site_Greenland2016