Nematode biodiversity and benthic trophic state are simple tools for the assessment of the environmental quality in coastal marine ecosystems

Abstract

A high biodiversity is essential to guarantee the stability and functioning of coastal marine ecosystems. In this perspective, the Marine Strategy Framework Directive provides prescriptions to maintain (or restore) marine biodiversity in order to achieve a Good Environmental Status (GES). Eutrophic conditions-as determined by the accumulation of sedimentary organic matter (OM)-are often associated with biodiversity loss, so that eutrophic conditions are often considered a prerequisite or a proxy for degraded ecological conditions. The aim of this study was to investigate the feasibility of the combined use of benthic trophic status and nematode biodiversity as integrated indicators of the environmental status of marine coastal ecosystems. To achieve this objective, we investigated nematode species diversity and assemblage composition in three areas of the Adriatic Sea, characterised by different OM quantity and biochemical composition (as proxy of sedimentary trophic status) and affected by different levels of anthropogenic impact. We show that, on the basis of OM quantity and biochemical composition, the investigated sites can be classified from oligo-to meso-trophic, whereas the analysis of nematode biodiversity indicates that the ecological quality status (EQS) ranged from bad to moderately impacted. This result provides evidence that trophic status and environmental quality assessments are not interchangeable tools for the assessment of marine ecosystems EQS. Rather they should be considered as complementary proxies for the overall assessment of the (good) ecological status. Data reported here also indicate that the loss of benthic biodiversity, whatever the source of disturbance, may be associated to a decrease of the functional diversity (either as feeding and life strategies traits), which might have important consequences on ecosystems functioning. Our results suggest that the GES cannot be defined uniquely in terms of sedimentary trophic status, especially when many other multiples stressors can contribute to determine the overall environmental quality of the investigated ecosystems. Nematode biodiversity is highly sensitive to differences in ecological conditions at different spatial and temporal scales and it can provide reliable and complementary information for the assessment of the environmental status in marine coastal sediments.

Diversity, Abundance, Spatial Variation, and Human Impacts in Marine Meiobenthic Nematode and Copepod Communities at Casey Station, East Antarctica

“…Coherence curves for nematodes ( Figure 5) provided some insights into the use of certain genera as indicators, particularly when compared to findings in previous studies. Each location exhibited a group of nematode taxa genera which were characteristic of that location ( Figure 5) and in some instances may be indicative of a pollution response., e.g., Bianchelli et al (2018). Several genera that have been shown to respond to different types of disturbances in other studies are highlighted below.…”

Sedimentary Organic Matter, Prokaryotes, and Meiofauna across a River-Lagoon-Sea Gradient

“…50% of the terrigenous flux into the whole basin), the sediments of the north western Adriatic are characterized by a strong Due to the large inputs from the Po river (which alone accounts for ca. 50% of the terrigenous flux into the whole basin), the sediments of the north western Adriatic are characterized by a strong accumulation of organic loads [9,[38][39][40][41][42], which have, for years, triggered hypoxic crises [43][44][45]. Indeed, the NW Adriatic Sea, which is the most productive basin of the entire Mediterranean Sea, has experienced huge and long-lasting anthropogenic environmental alterations in the last 50 years.…”

Meiofauna communities’ response to an anthropogenic pressure: The case study of green macroalgal bloom on sandy beach in Brittany

“…This would not be detected when merely considering the α-diversity, as the α-diversity usually does not reflect the β-diversity(Gambi et al, 2014).Richtersia spp., abundant at the unimpacted beach of Anse de Dinan generally inhabits un-impacted systems and is a proxy for good environmental status(Moreno et al, 2011). At the impacted beach, the most represented genera Microlaimus, Viscosia and Marylynnia were reported as less sensitive genera, tolerant to high organic loads and proxy of a moderate quality status of the system(Jouili et al, 2017;Franzo et al, 2018;Bianchelli et al, 2018). Nevertheless, other opportunist and more tolerant genera known to be proxy of a poor environmental quality status were found at both beaches, e.g.…”