Evaluation of seasonal variability in the food-web properties of coastal lagoons subjected to contrasting salinity gradients using network analyses

Assessing benthic macroinvertebrate communities' spatial heterogeneity in Mediterranean transitional waters through eDNA metabarcoding

Transitional waters are important habitats both for biodiversity and ecological functions, providing valuable natural resources and relevant ecosystem services. However, they are highly susceptible to climate changes and anthropogenic pressures responsible for biodiversity losses and require specific biomonitoring programs. Benthic macroinvertebrates are suitable as ecological indicators of transitional waters, being affected by biological, chemical, and physical conditions of the ecosystems about their life cycles and space-use behaviour. The advent of high-throughput sequencing technologies has allowed biodiversity investigations, at the molecular level, in multiple ecosystems and for different ecological guilds. Benthic macroinvertebrate communities' composition has been investigated, at the molecular level, mainly through DNA extracted from sediments in marine and riverine ecosystems. In this work, benthic macroinvertebrate communities are explored through eDNA metabarcoding from water samples in a Mediterranean transitional water ecosystem. This research highlighted the validity of eDNA metabarcoding as an efficient tool for the assessment of benthic macroinvertebrate community structure in transitional waters, unveiling the spatial heterogeneity of benthic macroinvertebrate communities correlated to the measured environmental gradients. The results suggest that peculiar features of transitional water ecosystems, such as shallow waters and limited currents, facilitate the assessment of benthic macroinvertebrate communities through environmental DNA analysis from surface water samples, opening for more rapid and accurate monitoring programs for these valuable ecosystems.

Two Sides of the Same Coin: A Theoretical Framework for Strong Sustainability in Marine Protected Areas

In 2014, the Italian Ministry of the Environment and Protection of the Territory and the Sea (MATTM) launched the “Environmental Accounting in the Marine Protected Areas” (EAMPA) project, which proposed a new accounting model for Marine Protected Areas (MPAs). The model foresaw the integration of ecological and economic components in classical accounting schemes through the quantification of stock and flows embracing both the perspectives. The project, which ended in 2019, allowed the testing and the realization of the multidisciplinary framework. Later, in the context of the EU Interreg “Integrated management of ecological networks through parks and marine areas” (GIREPAM) project, an upgraded version of the EAMPA framework was developed, including additional but fundamental components leading to a more detailed and complete assessment as well as a better theoretical definition. The definitive management framework is outlined through the creation of the two parallel paths, but it provides as a final result three balances from the strong sustainability perspective: ecocentric, anthropocentric and integrated. To ensure that sustainability is obtained, all the three balances must guarantee a positive net benefit for humans and nature alike.

Can an oligotrophic coastal lagoon support high biological productivity? Sources and pathways of primary production

Coastal lagoons are among the most productive systems in the world. Many marine species make use of this by entering the lagoons as juveniles for nursery and growth before returning to the sea for reproduction. Humans take advantage of such fish migration processes by fishing, and exploit the high productivity for aquaculture activities. The Mar Menor is one of the largest coastal lagoons in the Mediterranean, sustaining relatively high fishing intensity despite the fact that it has traditionally been characterized as highly oligotrophic. However, in the last decades, this lagoon has suffered drastic changes induced by human activities. This has led to eutrophication, which started mainly as a consequence of changes in agricultural practices in the lagoon watershed, and triggered such fundamental changes in the system, as the mass development of jellyfish. The aim of this work is to capture and analyse the structure and functioning of the trophic web of the Mar Menor when it was still, in contrast to other coastal lagoons, oligotrophic, to provide a start point for analysing the consequences of changes in the distribution of macrophyte meadows and of eutrophication. We have compiled a detailed trophic model of this lagoon, comprising 94 compartments, using an ECOPATH model to capture the period 1980-1995. At this time the lagoon was an autotrophic system with a high net surplus of production that reached 9124.31gC/m2/year, while the production/biomass (P/B) ratio reached 34.56 and the total primary production/total respiration ratio was 7.01. The lagoon exported a 38.46% of total flows, including the catch by fishing, and 44.40% went to detritus. The primary production was mainly benthic (99.4%) due to the microphytobenthos and macrophytes. However, despite the fact that total fishery landings in the study period ranged between 144,835.5 and 346,708.5 kg, the gross efficiency was low, making up only 0.005% of the net primary production. This could partly be explained by the high trophic level of the fish catch (2.9), but mainly because most of the primary production (10,532.06 gC/m2/year) went directly to the detritus pool and was accumulated in the sediment in the Caulerpa prolifera meadows. We suggest several reasons why such high productivity coincided with low chlorophyll concentrations and good overall water quality: 1) the domination of both benthic biomass and primary production over pelagic ones with a high biomass of filter feeders, detritus feeders and scavengers, 2) high species diversity, complex and long food webs characterized by low connectance,3) the export of a significant part of the production from the system, and 4) the accumulation of surplus organic matter (as detritus) in sediments. We compare the food web of the Mar Menor in this mentioned oligotrophic stage to those of ten other lagoons in pursuit of more general implications regarding lagoon ecosystem functioning.