Phytoplankton community composition in relation to environmental variability in the Urdaibai estuary (SE Bay of Biscay): Microscopy and eDNA metabarcoding.

Phytoplankton monitoring is essential for the global understanding of aquatic ecosystems. The present research studies the phytoplankton community of the Urdaibai estuary, combining microscopy and eDNA metabarcoding for the first time in the area. The main aims were to describe the phytoplankton community composition in relation to the environmental conditions of the estuary, and to compare the two methods used. Diatoms Minutocellus polymorphus and Chaetoceros tenuissimus dominated the outer estuary, being replaced by Teleaulax acuta (cryptophyte), Kryptoperidinium foliaceum (dinoflagellate) and Cyclotella spp. (diatom) towards the inner area. This change was mainly prompted by salinity and nutrients. Metabarcoding revealed the presence of 223 species that were not observed by microscopy in previous studies in the estuary. However, several characteristic species (e.g., K. foliaceum) were only detected with microscopy. Additionally, microscopy covered the limitations of eDNA metabarcoding concerning quantification. Thus, to give a full insight, a combination of techniques is recommended.

Perception, demand and user contribution to ecosystem services in the Bilbao Metropolitan Greenbelt.

Peri-urban ecosystems are often managed as recreation areas or to enhance aesthetic value on the urban fringe. Scholars and land-use practitioners lack a current understanding of the supply of and the demands for these peri-urban ecosystem services (ES). In this study, we analysed the perceptions of 500 users and interest groups regarding the ES provided by the Bilbao Metropolitan Greenbelt (BMG) ecosystems in northern Spain, and we compared these perceptions to the demands for ES. The objective of this study is to understand user preferences and to thereby better orient land use planning. The results show that the demand for ES in the BMG did not correspond to what users perceived these ecosystems to provide. The respondents' perceptions appeared to be related to the management practices in the area, whereas their demand was related to the benefits they would like to obtain from the BMG. The interviewees were in favour of improvements to peri-urban rural areas, and the results suggested that the authorities should highlight the role of the BMG ecosystems with respect to regulating services and historic and cultural values to improve people's awareness of the ecosystems' capacity to provide benefits to society. Application of this framework also highlighted that there were differences in the perception of and demand for ES among different user groups. This holistic method of matching user demand with policy could be a useful tool to reorient ES-based land planning.

Potential risk of harmful algae transport by ballast waters: the case of Bilbao Harbour.

Ballast water exchange was measured for the first time in Bilbao Harbour, one of the most active of northern Spain. Between 1997 and 2006, 41,900,980.34 ballast water tn were loaded and 13,272,709 tn were discharged. Bilbao Harbour appears to be mainly a source of ballast water, 90% of which would be discharged in European harbours. We estimated that vessels carrying liquid and solid bulk have higher probabilities of exporting ballast water, whereas those with liquid bulk and containers are more likely to introduce it. From 30 potentially harmful phytoplankton species identified to date near harbour facilities, there would be a high risk of exporting at least Alexandrium minutum, Dinophysis sp., Heterosigma akashiwo, Karlodinium sp., Ostreopsis cf. siamensis, Pfiesteria-like and Prorocentrum minimum. Invasion risk by ballast water was tested by analyzing the response of six strains of H. akashiwo from different geographic areas to varying salinity. Results show that successful growth of foreign strains would be possible.