Temperature-dependent impacts of allelopathy on growth, pigment, and lipid content between a subpolar strain of Synechocystis sp. CCBA MA-01 and coexisting microalgae

Abstract

Picocyanobacteria represent the main fraction of ocean primary production and, due to the effects of ocean acidification and an increase in seawater temperature, this group is expected to be favored in future scenarios. For this reason, we studied the ecophysiological response of picocyanobacteria to increases in water temperature by testing the allelopathic activity of a subpolar strain of Synechocystis sp., grown at a temperature range of 10-20°C, against coexisting microalgae. We showed that cell-free filtrates of Synechocystis sp. inhibited growth and the maximum quantum yields of PSII (F v /F m) of Porphyridium purpureum, Fistulifera sp., and Chlorella vulgaris, and the negative effect of the picocyanobacterium was stronger at the highest temperatures at which Synechocystis sp. was grown. Similarly, in P. purpureum, the effect of filtrates reduced chlorophyll a (Chl a) and carotenoids (Car) content, and the effect depended on the temperature at which the picocyanobacterium was grown. The lipid content was observed to increase in all species, and the allelopathic effect was the strongest at the highest temperature in which Synechocystis sp. was grown. The results of the present study predict a stronger allelopathic effect of picocyanobacteria against competitors with rising temperatures. They also suggest that the potential effect of climate change would benefit this group in future phytoplankton communities.

Geographical and Seasonal Thermal Sensitivity of Grazing Pressure by Microzooplankton in Contrasting Marine Ecosystems

“…Compounds produced by dominant phytoplankton groups in coastal and open-ocean areas (e.g., PUAs by diatoms, microcystins-like compounds by Synechococcus ) have been shown to inhibit microzooplankton growth in natural communities ( Lavrentyev et al, 2015 ; Sliwinska-Wilczewska et al, 2017 ). These allelopathic effects can be enhanced by warming ( Felpeto et al, 2019 ) and nutrient-limited conditions ( Fistarol et al, 2005 ). Also, warmer environments and/or low (or limiting) nutrient availability can lead to increased phytoplankton carbon:nutrient stoichiometry, i.e., seston with reduced nutritional quality ( De Senerpont Domis et al, 2014 ), which constitutes an effective defense mechanism against herbivore predators ( Branco et al, 2020 ), and could help explain inverse relationship between temperature and grazing pressure found in temperate, tropical open-ocean and polar coastal ecosystems.…”

The Importance of Allelopathic Picocyanobacterium Synechococcus sp. on the Abundance, Biomass Formation, and Structure of Phytoplankton Assemblages in Three Freshwater Lakes

“…Similar observations have been also made for other picocyanobacterium Synechocystis sp. [28]. Contrary to that, Synechococcus sp.…”

“…The allelopathic activity between marine Synechococcus strains CC9605, CC9311, and WH8102 has also been showed by Paz-Yepes et al [27]. There are also reports of allelopathic activity of marine picocyanobacteria of the genus Synechocystis CCBA MA-01 [28]. In these studies, it was shown that picocyanobacteria of the genus Synechococcus and Synechocystis can produce and release unidentified allelopathic compounds that have both a negative and positive effect on selected cyanobacteria and microalgae.…”

“…was able to inhibit Fistulifera sp. growth [28]. The susceptibility of target Bacillariophyceae to allelochemicals may depend on the nature of allelopathic compounds to which they are exposed, because the same target organisms may responsd differently to the exudates obtained from different donor organisms.…”

First Polyphasic Study of Cheffia Reservoir (Algeria) Cyanobacteria Isolates Reveals Toxic Picocyanobacteria Genotype

“…These blooms led to the death of bottom flora and benthic fauna and the loss of valuable resources of fish (eel and mullet) and mollusks [62]. Śliwi ńska-Wilczewska et al [57] and Felpeto et al [63] suggest that picocyanobacteria blooms are a new phenomenon that requires comprehensive studies. Although the impacts of climate change on picocyanobacterial blooms are diverse, most current evidence suggests that this process increases the amplitude and frequency of these events [57,64].…”