Seabird guano enters coastal waters providing bioavailable substrates for microbial plankton, but their role in marine ecosystem functioning remains poorly understood. Two concentrations of the water soluble fraction (WSF) of gull guano were added to different natural microbial communities collected in surface waters from the Ría de Vigo (NW Spain) in spring, summer, and winter. Samples were incubated with or without antibiotics (to block bacterial activity) to test whether gull guano stimulated phytoplankton and bacterial growth, caused changes in taxonomic composition, and altered phytoplankton-bacteria interactions. Alteromonadales, Sphingobacteriales, Verrucomicrobia and diatoms were generally stimulated by guano. Chlorophyll a (Chl a) concentration and bacterial abundance significantly increased after additions independently of the initial ambient nutrient concentrations. Our study demonstrates, for the first time, that the addition of guano altered the phytoplankton-bacteria interaction index from neutral (i.e. phytoplankton growth was not affected by bacterial activity) to positive (i.e. phytoplankton growth was stimulated by bacterial activity) in the lownutrient environment occurring in spring. In contrast, when environmental nutrient concentrations were high, the interaction index changed from positive to neutral after guano additions, suggesting the presence of some secondary metabolite in the guano that is needed for phytoplankton growth, which would otherwise be supplied by bacteria.
The greatest threat scleractinian corals face today is accelerated climate change. Assuming that most scleractinians are incapable of genetic adaptation to rapid global changes, the alternative response would be phenotypic plasticity, which is classically described as acclimatization. With the purpose of establishing a baseline for the study of acclimatization in corals of the Pacific coast of Mexico, we assessed the molecular and physiological response of 36 colonies of 3 Pocillopora morphospecies (Pocillopora cf. capitata, Pocillopora cf. damicornis, and Pocillopora cf. verrucosa) located at 2 sites (east and west) on Carrizales Reef. Our results show higher incidence of light and chlorophyll concentrations in seawater samples from the west side, suggesting the presence of at least 2 microenvironments with more and less light in the reef. In response, coral morphospecies from the west side showed higher gene expression and significant differences in pigment concentrations, endosymbiont densities, and metabolic markers (RNA, DNA, and proteins). Given the present concern about the future of coral reefs, we consider that the present study could be used as a baseline for the study of the physiological and molecular plasticity of Pocillopora corals in Mexican waters, so conservation strategies could be developed for key morphospecies in coral reefs on the Pacific coast of Mexico.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.