RESUMEN
In coastal lagoons, eutrophication and hydrology are interacting factors that produce distortions in biogeochemical nitrogen (N) and phosphorus (P) cycles. Such distortions affect nutrient relative availability and produce cascade consequences on primary producer's community and ecosystem functioning. In this study, the seasonal functioning of a coastal lagoon was investigated with a multielement approach, via the construction and analysis of network models. Spring and summer networks, both for N and P flows, have been simultaneously compiled for the northern transitional and southern confined area of the hypertrophic Curonian Lagoon (SE Baltic Sea). Ecological Network Analysis was applied to address the combined effect of hydrology and seasonality on biogeochemical processes. Results suggest that the ecosystem is more active and presents higher N and P fluxes in summer compared to spring, regardless of the area. Furthermore, larger internal recycling characterizes the confined compared to the transitional area, regardless of the season. The two areas differed in the fate of available nutrients. The transitional area received large riverine inputs that were mainly transferred to the sea without the conversion into primary producers' biomass. The confined area had fewer inputs but proportionally larger conversion into phytoplankton biomass. In summer, particularly in the confined area, primary production was inefficiently consumed by herbivores. Most phytoplanktonic N and P, in the confined area more than in the transitional area, were conveyed to the detritus pathway where P, more than N, was recycled, contributing to the unbalance in N:P stoichiometry and favouring N-fixing cyanobacteria over other phytoplankton groups. The findings of this study provide a comprehensive understanding of N and P circulation patterns in lagoon areas characterized by different hydrology. They also support the importance of a stoichiometric approach to trace relative differences in N and P recycling and abundance, that promote blooms, drive algal communities and whole ecosystem functioning.
Asunto(s)
Ecosistema , Nitrógeno , Nitrógeno/análisis , Fósforo/análisis , Biomasa , Fitoplancton , EutrofizaciónRESUMEN
Engaging relevant stakeholders to identify ecosystem services is an important step in ensuring better management actions and nature protection. In this study, we involved three stakeholder groups that gave their opinions on different aspects regarding the usage, threats and protection of ecosystem services in the Nemunas Delta region (south-eastern Baltic Sea). Opinions from 178 respondents, representing local farmers, birdwatchers and scientists were collected in order to evaluate the importance of ecosystem services and to distinguish the most effective actions to sustain them. Despite many differences, there was a clear consensus among all three respondent groups about the importance of some ecosystem services such as water quality, water cycle, habitats for migratory animals, existence value, nature watching, subject for education and research and recreation. Birdwatchers appeared to be helpful in ecosystem services evaluation for their experience-based knowledge in this study region, but the differing perceptions of different groups on the majority of ecosystem services showed how important it is to include more than one stakeholder group in the assessment. The respondents did not agree about the actions needed to sustain ecosystem services--this highlights a need for compromises between anthropogenic activities and environmental protection, while an agreement on the necessity (willingness) to preserve natural values points to future development directions for the Nemunas Delta Region.