A review of Italian research on free-living marine nematodes and the future perspectives on their use as Ecological Indicators (EcoInds)

Abstract

The use of free-living marine nematodes as ecological indicators (EcoInds) of human impacts has increased greatly in Italy since 1990. This paper is a summary of the Italian research experience in the study of nematode assemblages of shallow water habitats, and provides a breakdown of the most important insights that have been obtained so far. Although nematodes are among the best candidates for the Ecological Quality (EcoQ) assessment in the benthic domain, many guidelines need to be developed and limits overcome. Italian research has certainly contributed to the achievement of this purpose with highly focused local investigations on the effects of specific stressors (riverine and sewage discharge, aquaculture, trace elements and hydrocarbons), but also to a large extent with wider analyses aimed at finding new and valuable tools for monitoring programs and useful nematode descriptors, in line with the European Directives. Currently, the Italian and foreign experiences in this field draw light to the fact that the best nematode descriptors for the EcoQ assessment are the taxonomic composition and life strategy traits. However, nematode worldwide research is running the risk of being marginalized because of the relatively narrow scope of most contemporary studies. Nematode researchers should work in a nematologist community in order to better promote the use of nematodes such as EcoInds in the era of the Water Framework Directive (WFD) and Marine Strategy Framework Directive (MSFD). In the present paper, possible steps to obtain this goal are brought to the reader's attention and discussed.

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

“…For example, at Falconara, characterized by the lowest levels of trophic status and of biodiversity, some indicators of ecological quality status (c-p and ITD) give "moderate" or even "good" assessment in few sampling times (Table 8B). Such discrepancies suggest the need of combined simultaneous use of a wide range of ecological indicators, coupled with indicators of trophic status, in order to achieve a reliable environmental assessment (Semprucci et al, 2015a;2015b;Chen et al, 2018).…”

“…The ITD index was included in our analysis, since it still results a controversial indicator for EQS assessment. Indeed, ITD was first proposed as possible indicator and criticized after some years (Moreno et al, 2011;Semprucci et al, 2015a), since recent studies reported ambiguous influence of various stressors on ITD (Semprucci et al, 2015a;b). In this context, the ITD was included here in order to provide more information on its realibility, particularly for sites subjected to environmental multiple-stressors.…”

“…For these reasons, and due to their ecological characteristics, nematode diversity has been recently proposed as a possible indicator of Ecological Quality Status (EQS) of marine coastal ecosystems (Moreno et al, 2011;Semprucci et al, 2015a;b;. In particular, Moreno et al (2011) proposed an EQS classification based not only on nematode diversity levels (H' index), but also on their trophic diversity (ITD index) and life strategies traits (MI and c-p).…”

“…In particular, Moreno et al (2011) proposed an EQS classification based not only on nematode diversity levels (H' index), but also on their trophic diversity (ITD index) and life strategies traits (MI and c-p). In this regard, the ITD index still results a controversial indicator for the EQS assessment, for this reason it was included in our analysis in order to provide additional information on its use (Semprucci et al, 2015a).…”

“…Due to these characteristics, they have been utilised as indicators of a plethora of different environmental disturbances (Danovaro and Gambi, 2002;Steyaert et al, 2007;Moreno et al, 2008Moreno et al, , 2011Neher and Darby, 2009;Mirto et al, 2014;Pusceddu et al, 2014a;Hannachi et al, 2016): they, for example, are sensitive to hydrocarbon contamination (Danovaro et al, 1995;Mahmoudi et al, 2005;Losi et al, 6 2013) and organic enrichment (Essink and Keidel, 1998;Fraschetti et al, 2006;Moreno et al, 2008;Gambi et al, 2009), including biodeposition from aquaculture activities (Duplisea and Hargrave, 1996;Mazzola et al, 2000;Mirto et al, 2002;Vezzulli et al, 2008). In particular, previous studies have reported that the amount and the nutritional quality of sedimentary organic matter may affect nematodes biodiversity, and more specifically their taxonomic composition (Moreno et al, 2008;2015a;2015b;Bianchelli et al, 2016b).…”