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The current Common Agricultural Policy (CAP) 2014–2020 of the European Union (EU) proposed some environmental attempts to contrast the biodiversity decline and mitigate the effects of intensive agricultural management systems. In the present work, the results of the effectiveness of set-aside management to enhance soil nematode biodiversity and soil fertility are reported. In a mid-term experimental trial, three different set-aside managements, with mowing in May or July and without mowing, were compared through conventional rotation to provide management indications in the context of Good Agricultural and Environmental Condition (GAEC) Standard 4.2 in fields located in three sites (North, Central and South Italy). Soil fertility was evaluated by determining available phosphorous, total organic carbon and carbon humification. Soil nematode diversity was explored by examining soil nematode community structure, assessing Maturity (MI), Plant Parasitic (PPI), Basal (BI), Enrichment (EI), Structure (SI), Channel (CI) indices and diversity-weighted abundance. The results indicated that set-aside management moderately increased the available phosphorous and organic carbon content and humification remained low; the greatest increase in organic matter was obtained with mowing in May, period not permitted by Standard 4.2. The set-aside efficiency was associated with the previous crop rotations, and the major advantages were found after intensive crop rotations. In general, under set-aside management the nematode colonizer species, mainly bacterivores, increased in abundance and richness while plant parasitic nematodes and predators remained constant. Mowing carried out in July (the permitted period by Standard 4.2), weakly improved the soil nematode community structure by increasing k-strategies within nematode populations. Interestingly, the indices confirm that shifts in nematode community composition occurred more as a result of previous management than of five years of set-aside managements: specifically, the site characterized by the longest and the most conservative rotation, showed the highest values in MI, PPI, EI, SI indices. The use of diversity-weighted abundance expressed as biomass showed that free living nematodes involved in nutrient mineralization (bacterial and fungal feeders) and plant parasitic nematodes are not efficiently regulated by predation. Finally, as many nematode families are affected by soil organic carbon content, the low organic carbon increases found under set-aside management systems likely determined a low improvement of soil nematode biodiversity. [ABSTRACT FROM AUTHOR]

A microcosm experiment was conducted to examine the effects of the pharmaceutical (penicillin G) on free living nematode communities of a Tunisian coastal zone (South-Western Mediterranean Sea). Sediments were contaminated with five penicillin G dose [D1 (3 mg L −1 ), D2 (30 mg L −1 ), D3 (300 mg L −1 ), D4 (600 mg L −1 ), D5 (700 mg L −1 )], and effects were examined after 30 days. Results showed significant differences between nematode assemblages from undisturbed controls and those from penicillin G treatments. Most univariate measures, including diversity ( H ′), species richness ( d ), equitability ( J ) and number of species ( S ) decreased significantly with increasing level of the antibiotic contamination. Results from multivariate analyses of the species abundance data demonstrated that responses of nematode species to the penicillin treatments were varied: Kraspedonema octogoniata and Paracomesoma dubium were eliminated at all the antibiotic doses tested and seemed to be intolerant species to penicillin G contamination; Oncholaimus campylocercoides although survived even the highest dose D5, showed definite reduction in its abundance and may be classified as “opportunistic” species at this dose, whereas, Nannolaimoides decoratus which showed a positive response with an increase in density even at highest concentration of contaminant, seems to be “penicillin G resistant” species. [ABSTRACT FROM AUTHOR]

The article presents a study on the role of bacterivorous nematodes for stimulating microbial growth and exopolymer production in marine sediment microcosms. For the study, researchers analyzed samples of muddy intertidal marine sediment in a tidal estuary during low tide at Dourduff River in France. They examined the influence of bacterivorous nematodes Diplolaimelloides meyli, Diplolaimelloides oschei, bacteria and diatoms. They found positive effects of the nematodes on microbial density and extracellular polymeric substance (EPS) production.

A microcosm experiment was used to examine the effects of nickel on offshore nematode communities of a Tunisian coastal zone (Southwestern Mediterranean Sea). Sediments were contaminated with three nickel concentrations [low (250 ppm), medium (550 ppm) and high (900 ppm)], and effects were examined after 30 days. Results showed significant differences between nematode assemblages from undisturbed controls and those from nickel treatments. Most univariates measures, including diversity and species richness, decreased significantly with increasing level of Ni contamination. Results from multivariate analyses of the species abundance data demonstrated that responses of nematode species to the nickel treatments were varied: Leptonemella aphanothecae was eliminated at all the nickel doses tested and seemed to be intolerant species to nickel contamination; Daptonema normandicum, Neochromadora trichophora and Odontophora armata which significantly increased at 550 ppm nickel concentration appeared to be “opportunistic” species at this dose whereas Oncholaimus campylocercoides and Bathylaimus capacosus which increased at all doses tested (250, 550 and 900 ppm) seemed to be “nickel-resistant” species. [ABSTRACT FROM AUTHOR]