RESUMEN
This paper looks at experiential feedback and the technical and scientific challenges tied to the MERITE-HIPPOCAMPE cruise that took place in the Mediterranean Sea in spring 2019. This cruise proposes an innovative approach to investigate the accumulation and transfer of inorganic and organic contaminants within the planktonic food webs. We present detailed information on how the cruise worked, including 1) the cruise track and sampling stations, 2) the overall strategy, based mainly on the collection of plankton, suspended particles and water at the deep chlorophyll maximum, and the separation of these particles and planktonic organisms into various size fractions, as well as the collection of atmospheric deposition, 3) the operations performed and material used at each station, and 4) the sequence of operations and main parameters analysed. The paper also provides the main environmental conditions that were prevailing during the campaign. Lastly, we present the types of articles produced based on work completed by the cruise that are part of this special issue.
Asunto(s)
Cadena Alimentaria , Plancton , Mar Mediterráneo , Estaciones del Año , OceanografíaRESUMEN
This study investigates the effects of polycyclic aromatic hydrocarbons (PAHs) on two potentially toxic Pseudo-nitzschia hasleana and P. mannii, isolated from a PAH contaminated marine environment. Both species, maintained in non-axenic cultures, have been exposed during 144 h to increasing concentrations of a 15 PAHs mixture. Analysis of the domoic acid, showed very low concentrations. Dose-response curves for growth and photosynthesis inhibition were determined. Both species have maintained their growth until the end of incubation even at the highest concentration tested (120 µg l-1), Nevertheless, P mannii showed faster growth and seemed to be more tolerant than P. hasleana. To reduce PAH toxicity, both species have enhanced their biovolume, with a higher increase for P. mannii relative to P hasleana. Both species were also capable of bio-concentrating PAHs and were able to degrade them probably in synergy with their associated bacteria. The highest biodegradation was observed for P. mannii, which could harbored more efficient hydrocarbon-degrading bacteria. This study provides the first evidence that PAHs can control the growth and physiology of potentially toxic diatoms. Future studies should investigate the bacterial community associated with Pseudo-nitzschia species, as responses to pollutants or to other environmental stressors could be strongly influence by associated bacteria.
Asunto(s)
Diatomeas/fisiología , Hidrocarburos Policíclicos Aromáticos/toxicidad , Contaminantes Químicos del Agua/toxicidad , Adaptación Fisiológica , Bacterias , Biodegradación Ambiental , Diatomeas/metabolismo , Ácido Kaínico/análogos & derivados , Fotosíntesis , Hidrocarburos Policíclicos Aromáticos/metabolismo , Contaminantes Químicos del Agua/metabolismoRESUMEN
Phytoplankton and bacterioplankton are the key components of the organic matter cycle in aquatic ecosystems, and their interactions can impact the transfer of carbon and ecosystem functioning. The aim of this work was to assess the consequences of chemical contamination on the coupling between phytoplankton and bacterioplankton in two contrasting marine coastal ecosystems: lagoon waters and offshore waters. Bacterial carbon demand was sustained by primary carbon production in the offshore situation, suggesting a tight coupling between both compartments. In contrast, in lagoon waters, due to a higher nutrient and organic matter availability, bacteria could rely on allochthonous carbon sources to sustain their carbon requirements, decreasing so the coupling between both compartments. Exposure to chemical contaminants, pesticides and metal trace elements, resulted in a significant inhibition of the metabolic activities (primary production and bacterial carbon demand) involved in the carbon cycle, especially in offshore waters during spring and fall, inducing a significant decrease of the coupling between primary producers and heterotrophs. This coupling loss was even more evident upon sediment resuspension for both ecosystems due to the important release of nutrients and organic matter. Resulting enrichment alleviated the toxic effects of contaminants as indicated by the stimulation of phytoplankton biomass and carbon production, and modified the composition of the phytoplankton community, impacting so the interactions between phytoplankton and bacterioplankton.