In a new Ocean Life paper, we show how allelochemicals released by toxic phytoplankton helps in the coexistence of more phytoplankton species than the number of limiting resources and thus promoting biodiversity
The principle of competitive exclusion tells us that the number of surviving species cannot exceed the number of limiting resources. However, in natural systems, many plankton species coexist depending on a limited number of resources. In isotropic environments, although nonequilibrium dynamics (i.e. limit cycle or chaotic oscillations) has been suggested to play a leading role in maintaining the desired coexistence of many species on limited variety of resources, these findings are still debated in literature. The explanation of the paradoxical diversity of phytoplankton in isotropic environments governed by equilibrium dynamics is still an unachieved goal.
In this paper, we proposed a possible solution for the famous paradox of plankton in isotropic environment. Using a minimal chemostat model we show that the interaction between toxic and non-toxic phytoplankton species with changing competitive effects among species due to allelopathy helps to promote the stable coexistence of many species on a single resource and hence can solve the paradox of plankton. We emphasize toxic phytoplankton as a keystone species that strongly uncovers its allelochemicals on other non-toxic phytoplankton and enhances the species persistence and diversity in aquatic ecosystems. In addition, we analyze the consistency of ecosystem functioning and species diversity using a number of approaches, such as sampling hypothesis with selection and complementarity effects, cascading extinction–reinvasion, and examining system dynamics at different enrichment levels and toxicity.
Read the paper here