Effects of Climate change on organisms, populations and ecosystems

Examples of changes in the distribution of the polychaetes (a) <i>Amphictene auricoma</i> and (b) <i>Levinsenia gracilis</i>
Examples of changes in the distribution of the polychaetes (a) Amphictene auricoma and (b) Levinsenia gracilis

Our climate change research aims at understanding how recent anthropogenic climate change affects the ecology and physiology of marine organisms. This is done through a variety of techniques, including the analysis of long-term time series, field surveys and laboratory mesocosm experiments.

Distribution Shifts

The earth’s climate is changing at an unprecedented rate. For many species it is unlikely that they can rapidly adapt to the locally changing conditions through phenotypic plasticity and adaptive evolution. The long-term persistence of species in the face of climate change therefore largely depends on the ability of the populations of the species to keep pace with moving climates. The extent to which shifts in the distribution of species keep pace with a changing climate is uncertain. If species cannot withstand a change in thermal habitat, this could ultimately lead to a drop in biodiversity over longer time scales under rapid climate change. Using existing time-series, the work at Bangor aims at identifying the rate at which species are moving in response to climate change, if they can move fast enough to keep pace with climate change (Hiddink et al., 2012), and which climate parameters they are tracking (e.g. bottom or surface, minimum, mean or maximum temperature). This research studies many different groups of organisms, ranging from macro-algae to commercial fish species (Hiddink and ter Hofstede, 2008) and seabirds. Our results so far show that marine invertebrates need to shift at different rates and in different directions to track the climate velocities of different temperature measures, and are therefore lagging behind most temperature measures (Hiddink et al., 2015).

Ocean Acidification

Acidification of the world's oceans by the absorption of anthropogenic CO2 is causing so much concern that it is gaining recognition alongside climate change as 'the other CO2 problem'. In the future, critically, pH levels will be lower than those experienced for the past 25 million yr. The biological effects of ocean acidification are still far from clear.

Studies on climate change include effects of ocean acidification on development and physiology of marine crustaceans and molluscs. Marine organisms, especially those inhabiting coastal waters experience natural levels of stress due to food limitation or reduced salinity for instance. A main question is what is the response of these organisms to such stresses in a scenario of ocean acidification. We therefore follow a multiple-stressor approach to OA where organisms are exposed to increased CO2 levels simulating those predicted by climate change scenarios (e.g. end of century) in combination with food, thermal or osmotic stress. Studies include both early life history stages (larval and juveniles) as well as mature organisms ( see Life Histories Physiology and Behaviour).

Effects of climate change on species interactions

Over the last decade or so there has been increasing recognition that the ecosystem level effects of warming can only be understood by considering interactions among species rather than in isolation. Experimental mesocosms are being used to examine the effect of warming on trophic interactions using a model consumer-producer system, the macroalga Ulva lactuca and the isopod Idotea granulosa. The work uses the metabolic theory of ecology as theoretical underpinning and critically addresses the emerging paradigm that warming causes the rates of consumption by higher trophic levels to outstrip rates of production to shift food web structure.