The nematode assemblage of a coastal lagoon (Lake Varano, southern Italy): ecology and biodiversity patterns

Abstract

Summary:This study was conducted in Lake Varano (southern Italy) in order to determine the environmental parameters that influence nematode taxonomic and functional diversity and how they influence them, and to classify for the first time the ecological quality status of a transitional environment. The general composition and level of taxonomic diversity were comparable with those reported for transitional environments worldwide. Principal component analysis revealed that the main environmental factors controlling the assemblages in terms of both composition and biological traits were grain size, organic matter, pollution load index and, only secondarily, salinity. Molgolaimus allgeni, Terschellingia longicaudata and Leptolaimus luridus showed higher values in relation to silt, organic matter and pollution load index, while Axonolaimus caudostriatus, Odontophora wieseri, Paramonhystera pellucida and Paracanthonchus longicaudatus showed higher values in relation to the redox potential and sand percentage. Salinity was detected as an influencing parameter only secondarily and particularly for Calomicrolaimus honestus, Daptonema normandicum, Thalassomonhystera parva and Sabatieria pulchra. With respect to functional traits, the trophic groups seemed to be mainly related to sediment type, which is in turn reflected by the nature of the available food. The maturity index, as well as c-p classes, did not always permit a clear interpretation of the interaction between anthropogenic and natural factors. However, the greater influence of the San Antonino and San Francesco Canals was perfectly revealed by the nematode assemblage. In accordance with the current ecological quality classes, Lake Varano can mainly be classified as having good to poor ecological quality status.Keywords: free-living nematodes; biodiversity; transitional environment; ecological quality; Lake Varano.La comunidad de nematodos de una laguna costera (Laguna de Varano, Italia meridional): patrones de la ecología y la biodiversidad Resumen: Este estudio tiene como objetivo analizar cuál y en qué medida los parámetros ambientales influyen en la diversidad taxonómica y funcional de los nematodos y clasificar por primera vez el Estado de la Calidad Ecológica (EQS) de un ambiente de transición como la laguna de Varano (Italia meridional). La composición y el nivel de divesidad taxonómica son comparables con los reportados en todo el mundo para TEs. El análisis de componentes principales reveló que los factores que controlan la composición y las características biológicas de las comunidades son el tamaño del gránulo, la materia orgá-nica (MO), el índice de aportes contaminados (PLI) y sólo secundariamente la salinidad. Molgolaimus allgeni, Terschellingia longicaudata y Leptolaimus luridus aumentan en número en relación con el limo, la MO y el PLI, mientras Axonolaimus caudostriatus, Odontophora wieseri, Paramonhystera pelúcida y Paracanthonchus longicaudatus muestran valores más altos en relación con el potencial redox y el porcentaje de arena. La salinida...

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

“…Armenteros et al, 2009;Moreno et al, 2009;Beyrem et al, 2010;Semprucci et al, 2010a). In order to classify the EcoQ status of Varano in accordance with WFD, the authors used the nematode parameters proposed by Moreno et al (2011) and subsequently by Semprucci et al (2014). On the basis of these thresholds, the EcoQ status of most of the stations could be mainly classified as moderate, followed by good and poor status, in agreement with the level of OM enrichment and trace element levels found.…”

“…Desmoscolecidae, Richtersia, Pomponema, Epacanthion), as documented by other authors, revealed negative correlations with organic enrichment and chemicals, and were also present in higher densities at the more pristine sites (Heip et al, 1985;Bongers et al, 1991;Mahmoudi et al, 2005). However, the limited number of genera suggested by the authors does not always allow for its use in habitats or geographical regions characterized by a different nematode community composition (Semprucci et al, 2014). Thus, the set of genera recommended in this study has to be implemented in order to create a more comprehensive list (in a sort of tolerance/sensitivity spectrum) of EcoInds.…”

“…Terschellingia, Paracomesoma, Daptonema and Sabatieria were, for example, selected as indicators of a poor ecological quality status because of their well-known tolerance to pollution (Danovaro et al, 1995;Austen & Somerfield, 1997;Warwick et al, 1997;Schratzberger et al, 2006;Steyaert et al, 2007;Semprucci et al, 2013aSemprucci et al, , 2014. These genera were found to be made up of more than 10% of the nematode assemblage in the disturbed sites, whereas they were not so abundant, or were even absent, in the undisturbed sites.…”

“…Such promising results obtained by the authors in this study allow them to suggest the use of biomass and allometric attributes as an alternative method to the taxonomic approach, which is time-consuming and requires taxonomic expertise. Semprucci et al (2014) classified for the first time the EcoQ of the TE of Varano. The lake did not display high values of trace elements or OM enrichment.…”

Meiofaunal Dynamics and Heterogeneity along Salinity and Trophic Gradients in a Mediterranean Transitional System

“…Among them, the largest amount of information on meiofaunal spatial pattern is available for the upper Adriatic Sea, including the Venice lagoon [14][15][16][17][18][19][20]. Meiofaunal diversity and assemblage structure are also well-documented in the southern part of the Adriatic Sea, including the Lesina and Varano lagoons [6,8,17,[21][22][23]. Instead, meiofaunal studies in transitional environments along the Tyrrhenian coast, with the exception of the Stagnone of Marsala (Western Sicily), are largely lacking [17,24].…”