Spatial Variation in Copepodamides production by Acartia spp., Centropages chierchiae and Paracalanus spp

Authors: Maria F. Pais a, Joana Cruz a, Tiago D. Garcia a, Erik Selander b, Sandra Lage a 

Affiliations: a Centro de Ciências do Mar do Algarve (CCMAR/CIMAR LA), Campus de Gambelas, Universidade do Algarve, 8005-139 Faro, Portugal; b Division of Functional Ecology, Department of Biology, Lund University, Lund, Sweden. 

Abstract: Copepodamides are polar lipids produced and released by copepods. When detected by microalgae, these chemical cues trigger defensive traits, including morphological changes, increased bioluminescence and toxin production, in harmful algal bloom (HAB) forming species. Copepodamides production is widespread in free-living calanoid and cyclopoid copepods across aquatic environments, and to date, 46 copepodamides have been described. However, only a few copepod species were tested for the presence of copepodamide, and the species-specific variability across sampling sites have not been yet tested. Therefore, the present study aims to characterize and compare the copepodamides profile in three copepods species across sampling sites of two aquatic environments, Ria Formosa coastal lagoon and Guadiana River estuary. Using Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS), we were able to annotate 58 copepodamides, including 22 new copepodamides structures, and assess their variability between these two environments. Marine copepods contain both copepodamide subgroups, the copepodamides (CA) and the dihydro-copepodamides (dhCA), whereas brackish copepods were largely dominated by dhCAs. Furthermore, there was a significant spatial variability across Ria Formosa sampling points and species-specific chemical signatures. Acartia spp. predominantly produced dhCA, while Paracalanus spp. produced predominantly CA. In contrast, Centropages chiechiae exhibited production of both subgroups.