Introduction
Promotion of ecologically beneficial forms of aquaculture has emerged as a policy priority in recent years (European Commission, 2021), with promotion of culture techniques that closely resemble natural systems. While still managed, t raditional carp ponds in Central and Eastern Europe are an example of a sustainable aquaculture technique that has been shown to contribute to the biodiversity and maintain regulatory functions of ecosystems , comparable to natural wetlands (Popp et al., 2019) . However, there may be varying management practices between farms, with differing intensities of production. Traditional carp ponds are thus complex socio-ecological systems, and t o make sure they are sustainably managed and regulated, environmental interactions must be understood. Ecological assessments for regulatory and management use should be simple, practicable in terms of farming operations, and cost-effective, in addition to making sure that human benefits from the system are not heavily compromised. The goal of this study was thus to develop a rapid decision support tool to determine the ecological outcomes of different management intensities .
Materials and methods
Aquatic biodiversity data of selected taxonomic groups (Amphibia, Gastropoda , Bivalvia, Insecta , Aves) and aquatic vegetation was sampled from 6 carp ponds of varying management practices from June – September 2023. Environmental parameters were also recorded. Species abundance data was used in biodiversity analyses, including the calculation of multiple d iversity indices expressed through Renyi diversity profiles, and multivariate analyses of ecological community composition. Collected biomass data was used to parametrise an Ecopath with Ecosim (EwE ) model for each production intensity. EwE models were used to determine ecosystem health indicators through ecological network analysis (Aubin et al., 2019).
Results and Discussion
The preliminary biodiversity analyses showed differences in biodiversity between different pond management regimes are evident , with more intensively managed systems varying more from the natural state. Diversity profiles showed that the natural pond had the highest biodiversity across all indices, whereas semi-intensively managed ponds showed higher species richness but lower Shannon-Weiner, Simpsons and Berger-Parker diversity than intensively managed ponds. Non-metric multi-dimensional scaling showed that semi-intensively managed and natural ponds tend to be more similar in terms of community composition . Further analysis of data collected in September 2023 is ingoing and will be included in further multivariate analyses to determine t he interactions of environmental variables and community composition and to carry out the ecological network analysis with EwE .
References
Aubin, J., Baizeau , V., Jaeger, C., Roucaute , M., Gamito , S., 2021. Modeling trophic webs in freshwater fishpond systems using Ecopath : towards better polyculture management. Aquac Environ Interact 13, 311–322. https://doi.org/10.3354/AEI00406
European Commission (2021). Strategic guidelines for a more sustainable and competitive EU aquaculture for the period 2021 to 2030. Brussels: Directorate-General for Maritime Affairs and Fisheries.
Popp, J., Békefi , E., Duleba , S., Oláh , J., 2019. Multifunctionality of pond fish farms in the opinion of the farm managers: the case of Hungary. Reviews in Aquaculture 11, 830–847. https://doi.org/10.1111/RAQ.12260