by Marina de Castro Deus
The biological interactions between species that live in close relationship with the seabed strongly depend on competition for space. These fouling organisms have different population and individual growth rates depending on local environmental conditions, and temperature increases due to climate change can influence the distribution range and the competitive ability of these species causing different abundance patterns in the community. Due to the difficulty of measuring interactions of these species experimentally, studies often use the latitudinal temperature gradient in order to gather information on individual species populations growth rates in response to the variation of temperature. These results can be used as a good resource for information on species-specific thermal responses, but do not provide information on the possible changes that temperature shifts can have on competitive interactions between marine species.
Lord and Whitlatch (2015), from the University of Connecticut conducted tests on thermal growth of fouling species over different latitudes, and several photo surveys measuring abundance and competitive overgrowth in 160 sites on the east and west coast of North America. The aim of the study was to correlate growth responses to temperature with changes in competition related to latitude. The results supported the authors’ hypothesis that elevated temperatures would lead to positive growth rates in the northern parts of the latitudinal range and decreased growth rates on the southern. The competition photo surveys also supported the hypothesis that competition rates across and within the sites would change in response to species’, different growth rates. Stronger competitors were the species with the highest growth rate, with the fastest growing species winning the competition for space. These results demonstrate that climate change will cause shifts in the competition rate of marine species, leading to changes in abundance and composition of these communities.
Lord, J., Whitlatch, R., 2015. Predicting competitive shifts and responses to climate change based on latitudinal distributions of species assemblages. Ecology 96, 1264–1274