Reduced Survival and Disruption of Female Reproductive Output in Two Copepod Species (Acartia clausi and A. tonsa) Exposed to the Model Endocrine Disruptor 17α-Ethinylestradiol

Estuaries are heavily impacted by pollutants from different sources such as urban sewage, industrial waste and agricultural runoff. Endocrine-disrupting chemicals (EDCs) are very concerning pollutants to estuarine wildlife, but little is known about their impact on microscopic biota such as zooplankton. The aim of this work was to investigate the effects of a model EDC, the 17α-ethinylestradiol (EE2), on two copepod species inhabiting the Basque coast (Southeastern Bay of Biscay) estuaries: Acartia clausi (autochthonous neritic species) and Acartia tonsa (non-indigenous brackish species). Female copepods were collected at population maximum time (spring for A. clausi and summer for A. tonsa) and exposed individually to 5 ng/L (low), 5 µg/L (medium) and 500 µg/L EE2 (high) doses, from environmental concentrations found in sewage effluents to toxicological concentrations. After 24 h exposure, the survival rate of experimental individuals was checked and the lethal concentration LC50 was calculated. The number of egg-producing females and the amount of egg laying and egg hatching were recorded. The integrated biomarker index (IBR) was calculated to integrate the overall effects of EE2 exposure. Both species had reduced survival rates at 500 µg/L, and the LC50 was lower in A. tonsa (158 µg/L) compared to A. clausi (398 µg/L). The number of eggs laid was significantly reduced in A. clausi at EE2 medium and high doses, while a reduction in the number of eggs in A. tonsa was observed only at the high dose. However, no significant differences were detected in the egg hatching success of exposed A. clausi and A. tonsa. IBR index showed that EE2 had the most detrimental effects on A. tonsa and A. clausi females at the 500 µg/L dose. In conclusion, after 24 h of exposure, EE2 reduced female copepod survival and disrupted reproductive output, but only at high non-environmentally relevant concentrations.Funded by the Basque Government (IT1743-22) and UPV/EHU (UFI 11/37). T.H. was a holder of an Erasmus Mundus master grant

Impact of Colonizer Copepods on Zooplankton Structure and Diversity in Contrasting Estuaries

The impact of the occurrence of the non-indigenous species (NIS) Acartia tonsa, Oithona davisae, and Pseudodiaptomus marinus and of the range-expanding copepods Acartia bifilosa and Calanipeda aquaedulcis on the structure and diversity of zooplankton communities was analyzed using 18 years (1998-2015) time series from the contrasting estuaries of Bilbao and Urdaibai (Basque coast, Bay of Biscay). Changes in the structure of communities were assessed by using multivariate analyses of taxa abundances and changes in diversity by using descriptors of alpha, beta, and gamma diversity. The most evident changes occurred at the upper reaches of the estuary of Bilbao, where an abundant and less diverse brackish community, dominated by the NIS, A. tonsa and O. davisae, succeeded a low abundance and more diverse community of neritic origin. The later establishment of C. aquaedulcis was linked to further changes in the structure of the community and a progressive increase in diversity. The seasonal pattern of diversity at the inner estuary and the beta diversity in the estuary were also significantly affected by the arrival of the NIS and C. aquaedulcis. In contrast, the original low diversity brackish community of the estuary of Urdaibai, clearly dominated by A. bifilosa, was far less affected by the arrival of the same copepod NIS, and A. bifilosa remained as the species best related to the changes in zooplankton structure and diversity in the brackish habitats of the estuary.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by the University of the Basque Country (UPV/EHU) (UPV/EHU, GIU19/059) and the Basque Government (PIBA2020-1-0028 & IT1723-22) and through a grant to Z. Barroeta to carry out her PhD (UPV/EHUn Ikertzaileak Prestatzeko Kontratazio Deialdia 2016)

klima-aldaketa eta itsas plankton-ekosistema: inpaktua Ipar Atlantikoan eta euskal koltaldean

Gizakiok eragindako klima-aldaketaren inpaktua biosferaren osagai guztietan nozitzen ari da, eta modu eragingarriagoan Lurreko azaleraren bi heren baino zabalagoa den itsas plankton-ekosisteman. Hain zuzen, Ipar Atlantikoko plankton-ekosistema da gehien eta modu sistematikoagoan ikertu den itsas eremua, klima-aldaketak plankton-ekosistemetan bide duen eraginari buruzko informazio-iturri osatuena dena. Itsas eskualde honetan, behatu da berotze globalari egotziriko plankton-espezieen iparralderanzko lekualdatzea eta aldaketa fenologikoak gertatzen ari dela, eta era berean, badira plankton-ugaritasun, ekoizpen eta dibertsitatearen aldaketak, eta planktonaren eta bere kontsumitzaileen arteko erlazioen aldaketak ere. Azidifikazioaren eragina, berriz, gutxi ikertu da, eta ez da oso ondo ulertzen. Kostaldeko plankton-ekosistemei dagokienez, klima-aldaketari emandako erantzunak korapilatsuagoak eta identifikagaitzagoak dira, berotzearen efektuaz gain klima-aldaketak dakartzan beste eragile batzuen eta tokiko aldaketa antropogenikoen elkarrekintzaren ondorioz. Hala ere, euskal plataformako eta estuarioetako plankton komunitateetan ere azken urteotan behatuak dira klima-aldaketarekin zalantzarik gabeko zerikusia duten hainbat aldaketa, hala nola komunitate neritikoetan zein estuariotarretan berriki gertatu den ur beroetako hainbat espezieren agerpena eta hedapena. Egun, klima-aldaketak plankton-ekosistemaren gainean duen eragina agerikoa da, bai eskala globalean bai gure eskualdean, baina bere ondorioak hobeto ulertzeko eta aurreikusteko ezinbestekoa da denbora serieak eta iragarpen ereduak garatzea

Response of native and non-indigenous zooplankton to inherent system features and management in two Basque estuaries: A niche decomposition approach

The realized ecological niches of native zooplankton and non-indigenous species (NIS) were analysed in the contrasting estuaries of Bilbao and Urdaibai from 1998 to 2015 in order to study their responses to the particular features of each estuary and the biotic and abiotic changes along the study period. The marginality and tolerance of zooplankton taxa was estimated for the two estuaries together using the OMI analysis, whilst, by means of the WitOMI analysis, niches were differentiated into spatial subniches to assess the differences between estuaries and into temporal subniches to determine the variations in time within each estuary. The changes in the niche overlap of the main native and NIS species were calculated with the D-metric. Results showed that the combined effect of salinity gradients and seasonal variations, linked to temperature, defined the main spatio-temporal niches of zooplankton taxa in the overall environmental scenario of both estuaries. Thus, those factors separated winter-spring neritic, summer-autumn neritic, warm water affinity brackish and limnetic species. Secondarily, river discharge and hydrological stability accounted for the higher presence of freshwater and some brackish species in the estuary of Bilbao and tychoplanktonic organisms in the estuary of Urdaibai. At the regional scale the marginality and tolerance of zooplankton taxa reflected a combination of spatial and seasonal niche breadth and difference of abundance between estuaries. The number of taxa with niches not clearly explained by the environmental variables studied was higher in the estuary of Urdaibai, whilst the new arriving species occupied realized niches well defined by the environmental variables and overall zooplankton taxa showed a better discrimination from generalist to specialist behaviours in the estuary of Bilbao. This was related to inherent abiotic and biotic features of each estuary, which make the estuary of Urdaibai more refractory to the settlement of NIS species. Moreover, in the estuary of Bilbao, several neritic and brackish species experienced temporal changes in niche breadth and overlap that was attributed both to the environmental improvement related to rehabilitation plans in the system and the impact of the species that arrived during the study period. In the estuary of Urdaibai only small changes attributable to the limited impact of NIS were inferred, since no meaningful changes in environmental conditions were perceived.This work was supported by the University of the Basque Country through research funds to Consolidated Research Groups (GIU16/69) and through a grant to Z. Barroeta. The authors thank the WGEUROBUS of the International Council for the Exploration of the Sea (ICES) for facilitating research on P. marinus

The Role of Microplastics in Marine Pathogen Transmission: Retrospective Regression Analysis, Experimental Design, and Disease Modelling

Marine wildlife and aquaculture species can accumulate large amounts of marine microplastic debris (MMD) (<1 mm) carrying pathogens, thus threatening the health of marine ecosystems and posing a risk to food safety and human health. Here, we outline a theoretical three-perspective approach for studying the relationship between MMD and disease. First, we provide a framework for retrospective analysis of MMD and pathogen loads in marine animal tissues to assess the relationship between these and other environmental variables in order to decide whether a compound or pathogen should be considered an emerging substance or organism. Second, we describe an experimental design for testing the effects of a variety of microplastics on infection intensity in two model species (oysters and zebrafish). Finally, we create a theoretical susceptible–infected microplastic particle and pathogen transmission model for bivalves and fish. Overall, the experiments and models we propose will pave the way for future research designed to assess the role of MMD as a vector for marine and human pathogens. This multi-faceted approach needs to be an urgent priority of the EU Strategic Research Innovation Agenda for addressing marine disease challenges related to MMD.This work was conceived under the research framework outlined by the National Science Foundation Evolution and Ecology of Infectious Diseases (EEID) Program, grant OCE-1216220. Funding was provided by the University of the Basque Country (UPV/EHU, GIU19/059) and the Basque Government (PIBA2020-1-0028). We appreciate this support

Insights on the Origin of Invasive Copepods colonizing Basque Estuaries; a DNA Barcoding Approach

Background: The introduction of NIS to estuaries and coastal embayment is of great concern. Commercial ships’ ballast water discharge and the northwards progression of species due to the ongoing climate change arise as the main factors explaining the rising occurrence of NIS species in Northern Atlantic waters. In this regard, regular monitoring of the plankton communities is paramount as to be able to respond properly to this potential issue. Results: While monitoring the invasive copepod Acartia tonsa populations in the estuaries of Bilbao and Urdaibai (Basque country, Spain), we report here the Asian copepod Pseudodiaptomus marinus for the first time in the Iberian Peninsula waters. Individuals from both species were collected from July to October, 2013 for DNA sequencing of mitochondrial cytochrome c oxidase subunit I gene (MT-CO1). Phylogenetic analysis of MT-CO1 confirmed P. marinus identity. Conclusions: Phylogeographic distribution of A. tonsa haplotypes in Europe along with the Bilbao port traffic patterns suggested a secondary invasion from an European source to Basque estuaries. The successful establishment of the A. tonsa population and the appearance of Pseudodiaptomus marinus confirm the need for regular plankton monitoring of estuarine and port waters. This applies also to nearby systems as these populations could represent a source of future dispersal.DA’s work was supported by the ZabaldUz Program (PhD fellowship). SGIker technical and human support (UPV/EHU) is gratefully acknowledged. Thanks to T. Matellanes (Bilbao Port Authority) for providing maritime traffic data. Special thanks to the anonymous reviewers that greatly improved the different manuscript versions. The sampling program received funds from the University of the Basque Country (UFI11/37) and the Basque Government (GIC10/168)