Nematode communities of small farmland ponds

Abstract

The nematofauna of 14 farmland ponds, selected according to a gradient of surrounding agricultural land-use intensity, from five regions in North-West of Belgium were studied. The total nematode density (9-411 ind./10 cm(2) per pond), and especially the number of species (4-12 species per pond) was especially low in these ponds. In total, 17 genera of free-living benthic nematodes, belonging to 15 families, are identified. Tobrilus gracilis and Eumonhystera filiformis were the most common species and were found in 13 and 12 of the 14 sampled ponds, respectively. The genera Tobrilus and Eumonhystera jointly comprise 77% of the total nematofauna. Consequently, the investigated water bodies were dominated by deposit feeding Monhysteridae and/or by chewing Tobrilidae. Diplogasteridae and Rhabditidae, normally related with eutrophic habitats, were almost absent. In order to explain the variation of total density, diversity, feeding-types composition and the individual density of the six most important species within ponds as well, sets of environmental variables were statistically selected. It was demonstrated that morphologically very similar species can show highly different ecological properties. The presence of a substantial mud layer and of an overall high level of eutrophication as well as the presence of possibly associated anaerobic conditions are put forward as the main factors explaining the observed low density and diversity. Total phosphate concentration and sediment characteristics seem to be the most important variables to explain the nematode community structure. However, a clear pattern of environmental variables, agricultural land use and nematode assemblages was not observed

Relation between nematode communities and trophic state in southern Swedish lakes

“…Especially, T. gracilis was found to be widely distributed in habitats disturbed by different stressors (Prejs, 1977a, b;Eder & Kirchengast, 1982;Niemann et al, 1996;Bert et al, 2007) and together with B. stefanskii was indicative of high trophic levels in the Swedish lakes of our study. Further, two species of the highly abundant family Monhysteridae, M. paludicola and E. filiformis, dominated in eutrophic lakes but were also found to lesser extents in nutrient-poor lakes (Prejs, 1977a, b;, 2005aBert et al, 2007). E. pratensis, despite its euryoecious occurrence with respect to trophic gradients (Prejs, 1977a;Traunspurger, 1996;, was typical of eutrophic conditions.…”

Sediment characteristics and accumulation rates in constructed ponds

“…Plankton particles generated within the pond itself should settle more slowly than denser sand grains and accumulate primarily in deeper water. Sediment dry bulk density (dBD), nutrient content, and organic matter (OM) are often correlated with sediment particle size.Sediment particle size distribution, particulate OM, and nutrient content are known to influence meiofaunal invertebrate richness and abundance (Bert et al 2007) and the distribution of rooted macrophytes (Xie et al 2005). Macrophytes not only create habitat and resources for algal biofilms, invertebrates, and fish (DeClerck et al 2005) but also reduce water movement, thereby increasing sediment deposition (Madsen et al 2001).…”

Context‐dependent role of abiotic and biotic factors structuring nematode communities along two environmental gradients

“…and Punctodora sp. (Bert et al, 2007; Kazemi‐Dinan et al, 2014; Traunspurger, 2000). The dominance of Tobrilidae across the entire alkalinity gradient can be attributed to their preference for living in truly aquatic environments (Tahseen, 2012; Traunspurger, 2000) and to their nature of feeding on larval forms of small, soft‐bodied invertebrates and diatoms, which are often abundant in these environments (Zullini, 2006).…”