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
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.
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.