Interactions between microalgae prove to be crucial in red tides

[Spain] Researchers from the Department of toxic microalgae at the IEO’s Vigo Oceanographic Centre determined that competition between toxic and non-toxic microalgae species that inhabit the Canaries seabed can have both positive and negative effects.

The team has published the results of a research focused on the study of benthic dinoflagellates (living on substrates), a group of microalgae that is usually related to harmful algal blooms.

“The blooms of harmful algae, wrongly called red tides – because they do not always have colour – imply an increase in the concentration of microalgae that produce toxins, representing a risk both for human health and for the economy of a territory,” explains Maria Garcia-Portela, IEO predoctoral researcher and first author of the paper.

The study consisted of gathering two species and observing the effects of this coexistence, comparing it with controls, that is, comparing the behaviour that each species would have separately.

These interactions proved to be positive or negative as the case may be.

“The objective of this study is to put into practice in laboratory what is observed in real marine ecosystems such as the Canaries and see what effects occur,” says Garcia-Portela.

For the experiments, toxic species Ostreopsis sp., Gambierdiscus excentricus and Prorocentrum hoffmannianum were used, and a non-toxic one, Coolia monotis. All were taken from samples collected during a CICAN project campaign in Canarian waters.

First, a genetic study and an analysis of the toxins of each species were conducted. Afterwards, it was studied how the coexistence of each pair of species affects variables such as the level of growth, the state of the cell or its ability to adhere to the substrate.

In this study positive effects were observed, such as an increase in the ability to adhere to the substrate of Prorocentrum when competing with other species.

Negative but short-term effects were also observed, such as delayed growth and decreased mobility in Coolia or lysis in Gambierdiscus cells when encountered with Ostreopsis.

“All these results highlight the internal warfare that takes place in dinoflagellate communities and highlights the importance of studying the interactions among species in controlling the dynamics of microalgae blooms in marine ecosystems,” the researcher highlights.

 

View original article at: Interactions between microalgae prove to be crucial in red tides

 

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