Future climate change is predicted to affect the microbiome and condition of habitat-forming kelp.
Qiu Z, Coleman MA, Provost E, Campbell AH, Kelaher BP, Dalton SJ, Thomas T, Steinberg PD, Marzinelli EM
Proc Biol Sci. Feb 2019. doi: 10.1098/rspb.2018.1887
COMMENT: Researchers have studied the microbiome associated to one particular kelp species, Ecklonia radiata, to address whether climate change can alter this association and in turn, affect kelp growth and survival.
Given the ecological role that this species plays along the temperate Australian coastline, such impacts may affect entire coastal ecosystems.
Microbiomes and their hosts form biological systems that are susceptible of being impacted by climate changes. This is particular important for habitat-forming organisms.
In oceanic environments, kelps are the main habitat-forming species in temperate rocky reefs, but kelp forests all over the world are declining in part due to ocean warming and changes in water quality, and are predicted to decline further as climatic conditions change.
Two parameters, water warming and acidification, were tested in healthy collected kelps kept under controlled conditions. These parameters were selected to resemble the current and future conditions of the environment due to climate change.
Microbiome analysis showed strong differences in microbial populations among temperature and/or acidification treatments. Some taxa were more markedly affected by temperature, while some others were strongly affected by acidification.
Kelp tissues were also affected by acidification and temperature, showing blistering and lowering of photosynthetic yields. In blistered kelp, the microbial communities showed strong differences with respect to healthy kelp.
Although blisters in kelp were more prevalent in acidification conditions, this may be an indirect effect of changes in the microbiome associated to kelp, since changes in the microbiome populations were observed before changes in the kelp condition.
The structures of the microbial communities in healthy vs. blistered tissues were markedly different in all experimental conditions with one exception: the combination of both future temperature and acidification conditions, where microbiomes from healthy and damaged kelp were similar. This finding is coherent with other works in which the effects of warming and acidification have show antagonistic effects, tending to moderate their impact. However, this has to be addressed in a more complete way by performing long-term experiments.
Research works like this are needed to increase our knowledge of the relations between microbiomes and their hosts and the effects of this relation in the ecosystems.
Such understanding is, however, crucial in order to provide early warning signals and conserve and manage key marine ecosystems that underpin temperate reef biodiversity and functioning.