• Energy Research

We compared the performance of abundance- and biomass-based M-AMBI in the 13 major Italian lagoons, using a benthic dataset constituted by 208 sampling sites. The relative importance of ecological groups changed when using abundance or biomass, sometimes leading to an improved ecological status classification. Being biomass more ecologically relevant than abundance, the adoption of a biomass-based index may better describe the ecological status of lagoons, where the community is naturally disturbed and dominated by tolerant and opportunist species.

The summer of 2003 was the warmest summer in Europe since the 16th century. Its consequences on the fauna of a transitional ecosystem were studied through biodiversity, functional and ecological indicators, from summer 2002 to winter 2005. The heatwave caused considerable changes in the benthic community structure and relative composition, persisting in 2005. Animal assemblages switched from mollusc- to annelida-dominated. Biodiversity and functional indicators captured changes in community structure and composition, proving to be powerful tools to detect responses related to global warming. Ecological indicators rendered a monotonic response oscillating between bad and poor ecological status across the study period. The resilience of mollusc biocoenosis resulted limited with respect to other taxa, posing concerns about their conservation if, as predicted, the frequency of summers as hot as that of 2003 will progressively increase to become the norm at the end of this century.

Benthic invertebrates are good indicators of aquatic ecosystem health. Yet, environmental monitoring and assessment of community changes in relation to both natural and human sources of disturbance involves considerable efforts for sample processing and time-consuming identifications of organisms, which make challenging large-scale and continuous monitoring programs required under the current regulatory frameworks at European scale. The use of higher taxa (e.g. families) as surrogates for species is a mainstream approach to reduce cost and time associated to fine taxonomic resolution in environmental studies, especially concerning macro-invertebrate communities. However, this approach of ‘taxonomic sufficiency’ simply relies on the static grouping of organisms in taxa belonging to a single higher taxonomic level irrespective of their ecological relevance or difficulties in their taxonomic identification, leading to unnecessary losses of taxonomic detail or ecological information. A new approach, namely the Best Practicable Aggregation of Species (BestAgg), has been recently developed as an alternative procedure for species surrogacy. BestAgg is based on aggregating species in the minimum number of surrogates sufficient to depict species-level community patterns consistently, while capitalizing on ecological information. Although the approach has been successfully applied to marine and freshwater invertebrate assemblages, its effectiveness in transitional water systems, where the complex and highly variable environmental conditions may affect the performance of surrogacy methods, still remain untested. Here, we applied the BestAgg approach to quantifying spatio-temporal patterns of variability of macro-invertebrate assemblages from Mediterranean coastal lagoons (Northern Adriatic Sea). Surrogates were defined using species-level data from a representative lagoon system, which served as pilot study. Then, they were used to analyze macro-invertebrate assemblages in two independent lagoons in the same geographic area. Results showed that BestAgg surrogates were effective in depicting multivariate patterns of macro-invertebrate assemblages as at species level over and beyond potential variations among the investigated lagoons. The use of families, following a more classic approach based on taxonomic sufficiency, also provided results comparable to those obtained using species. However, with respect to families, BestAgg surrogates allowed an estimated timesaving of 40% higher while still retaining an equivalent amount of information on species-level patterns. More importantly, BestAgg allowed exploiting different criteria of species aggregation, leading to a set of surrogates more aligned with ecological/functional characteristics of organisms, suggesting that BestAgg approach may provide a fresh perspective for optimizing trade-offs between pragmatism and the need for relevant ecological information in environmental assessment and monitoring.

We studied the performance of the AZTI Marine Biotic Index AMBI manipulating input data collected from lagoonal ecosystems. Our data set consisted of macrofaunal abundance and biomass counts gathered at a variety of sites at which the disturbance status was known. Input data were also manipulated using a set of transformations of increasing severity. Biotic indices were calculated using raw and transformed abundance, biomass and production. Among the three categories of AMBI-based indices, medium transformation of data gave the highest correlation with pressures. However, increasing the severity of transformation generally resulted in a decrease of the correlation with environmental factors. The relative importance of ecological groups changed when using abundance or biomass, sometimes leading to an improved ecological status classification. Being biomass and production more ecologically relevant than abundance, using them to derive AMBI-based new indices seems intriguing, at least in lagoonal waters, where the community is naturally disturbed and dominated by opportunists.

A time series data of macrobenthic invertebrates of Valli di Comacchio lagoon (northern Adriatic) from 1996 to 2015, was analysed using Biological Traits Analysis, structural indices, AMBI and M-AMBI indices, with a twofold aim to: firstly, test the resilience of the system, and, secondly, test the influence of climate changes, in terms of temperature and precipitation pattern, on macrobenthic dynamics. Along the studied period macrobenthic community showed marked fluctuations, in terms of richness, diversity, biological traits and ecological groups, which could be related with environmental instability of the lagoon. At the same time, a general tendency towards a deterioration of ecological condition of the lagoon was observed, with a general decrease in species richness, diversity, percentage of sensitive species, and a general increase in the proportion of the more opportunistic trait modalities, such as deposit feeders, burrowing, infaunal and short living animals. Increasing yearly temperature explained only a small part of the variability of macrobenthic community, in terms of biological traits and diversity indices, and this was likely due to the effect of natural fluctuations of environmental parameters and anthropogenic disturbance. Nevertheless, all metrics used are consistent in identifying the response of benthic community to a severe disturbance, likely related with the summer heatwave in 2003. Less marked signs of disturbance were observed also in relations to the thermal anomaly of 2012. Biological Traits Analysis combined with more classical structural and ecological indices, proved to be efficient in identifying temporal changes of the community. Our results suggest that the expected increase in frequency, magnitude and duration of heatwaves could pose serious threat to the resilience capacity of lagoonal macrobenthic community.