Three new species of the Microlaimus genus (Nematoda: Microlaimidae) are described from sample sediments collected in the South Atlantic, along the Continental Shelf break of Northeastern Brazil. Microlaimus paraundulatus sp. n. possesses four setiform cephalic sensillae, a buccal cavity with three small teeth, arched and slender spicules and a wave-shaped gubernaculum. Microlaimus modestus sp. n. is characterized by four small cephalic sensillae, a buccal cavity with three teeth (one large dorsal tooth), cephalated spicules and a strongly arched gubernaculum in the distal region. Microlaimus nordestinus sp. n. is characterized by the following set of features: relatively long body, eight rows of hypodermal glands that extend longitudinally along the body and a funnel-shaped gubernaculum surrounding the spicules at the distal end. An amendment of the diagnosis is proposed for the genus.

Seagrass meadows are hot spots of biodiversity and play a key role in the provisioning of ecosystem goods and services but are often subjected to a regression due to a combination of multiple anthropogenic and climate-induced impacts. The ecological restoration of these habitat-forming species is a priority to reverse biodiversity loss and for the recovery of key ecosystem functions. Here we investigated the effects of seagrass (Cymodocea nodosa) restoration action on benthic biodiversity recovery assessed by a time-series analysis carried out for one year. We used nematode assemblages, the most widespread metazoan on global sediments, as a proxy of benthic biodiversity and compared the species richness, expected species number (ES51) and composition in donor and in restored seagrasses and in the adjacent unvegetated sediments. One year after the intervention, nematode biodiversity in restored seagrasses was more similar to that of the donor site than in unvegetated sediments, suggesting a progressive recovery. Overall, the nematode biodiversity of the restored seagrasses resulted in an intermediate level between unvegetated and pristine seagrass meadows, providing evidence that restoration intervention contributed to biodiversity recovery. Pristine and restored seagrass meadows hosted a high number of exclusive species, which resulted in an increase in the overall biodiversity in the investigated location. Our results indicate that the restoration of seagrass meadows has positive effects on benthic biodiversity and contributes to enhance the local biodiversity.

Cold seeps provide high environmental heterogeneity for marine benthos. Site F is one of the active cold seeps in the South China Sea. In this study, free-living marine nematode communities were investigated at Site F and the adjacent deep-sea area. A total of 67 genera and 32 families were identified. The mean density at cold seep sites ranged from 13.6 to 181.8 ind./10 cm2, and that at the adjacent deep-sea sites ranged from 36.9 to 301.4 ind./10 cm2. At cold seep sites, the most dominant nematode genera were Desmoscolex, Pierrickia, Sabatieria, Halalaimus, and Dorylaimopsis while at deep-sea sites, the most dominant genera were Retrotheristus, Thalassomonhystera, Desmoscolex, Cobbia, and Halalaimus. Deposit feeders of nematodes were dominant at all sites. Results of biological trait analysis showed that there was high environmental heterogeneity for nematodes at Site F. Water depth, sediment organic matter content, and sand proportion had important influences on nematode communities.

Fish products in Slovakia have been heavily infected with Anisakis spp. larvae, which causes human anisakiasis. We found larvae in all tested samples of frozen Atlantic herring. Anisakid allergen t-Ani s7 testing revealed 2 positive cases in humans, signaling need for health authorities to closely monitor zoonotic marine parasites, even in inland areas.

Wastewater treatment plants (WWTPs) represent major point sources of pollution in coastal systems, affecting benthic ecosystems. In the present study, we assessed the potential role that WWTPs have in shaping nematode communities and established baseline knowledge of free-living nematode community structures in St. Andrew Bay, Florida. Sediment samples were collected from four sites representing areas of WWTP outflow and areas with no apparent outflow, during the winter and summer. Nematode communities across sites were significantly different, and the differences were strongly associated with the distance to the nearest WWTP. While the communities were not different along transects at each site, nor across seasons, community dissimilarity across sites was high, implying strong contrasts throughout the bay system. Dominance of tolerant, opportunistic genera and Ecological Quality Status assessments suggest that the system is stressed by organic enrichment, possibly linked to the WWTPs. Our results suggest that knowledge on the life-history of dominant genera is imperative to assess the ecological quality of a benthic system, in addition to taxonomic and functional metrics. Considering the value of marine nematodes as bioindicators, more work should be done to monitor temporal variability in nematode communities in this system as future infrastructure changes alter its dynamics.

Free-living marine nematodes are valuable biological indicators for different environmental disturbances. Their taxonomic composition and functional traits often respond to environmental changes. In this study, marine nematodes, collected from the Bohai sea on the northeastern coast of China in 2014, were investigated in terms of their taxonomic composition and functional traits. Furthermore, the environmental quality of the investigated area was assessed based on nematode metrics. The studied nematode community showed spatial variation in taxonomic and functional composition, in response to changes in environmental variables such as sediment chlorophyll-a, phaeophytin-a, organic matter content, silt-clay content etc. Overall, high percentage of tolerant marine nematodes species or colonizers predominated, suggesting a disturbed environmental condition of the study area. Further results from the environmental quality assessment based on nematode metrics indicated a moderate quality status at the most investigated stations.

Cyatholaimidae is a common and diverse family of mainly marine nematodes, potentially, with a large number of species to be discovered. The taxonomy of the group is marked by a lack of information about the evolutionary history of the characters and of detailed descriptions of morphological structures that may be taxonomically relevant. Two new species of the family are described from a sublittoral region in Southeastern Brazil, emphasizing the importance of the distribution and morphology of pore complex and pore-like structures present on the cuticle. The taxonomic importance of the cuticle ornamentation and spicule shape for the Biarmifer species, as well as the precloacal supplements structures of Pomponema species, are discussed. Biarmifer nesiotes sp. nov. differs from other species of the genus by the presence of eight longitudinal rows of pore complex on the cuticle and by the shape of the copulatory structure. Pomponema longispiculum sp. nov. differs from the most similar species, P. stomachor Wieser, 1954, by the smaller number of turns of the amphidial fovea, the shorter tail and the beginning of the cuticle lateral differentiation (3/4 of the pharynx length vs. end of the pharynx, respectively). We also obtained the SSU rDNA sequence from Pomponema longispiculum sp. nov., which is closely related to Pomponema sp. (MN250093) by about 91%. Updated tabular keys to species identification of each genus (Biarmifer and Pomponema) are included, containing morphometric data, characters related to cuticle ornamentation, and copulatory structures.

Free-living nematodes were investigated in three Mediterranean commercial ports (Ancona and Trieste, Italy; Koper, Slovenia) in terms of abundance, diversity and functionality. Results indicated that r-strategist genera were dominant in all ports and that a more diverse assemblage characterized Trieste, despite the high contamination levels, suggesting a potential adaptation to long-standing contamination. The main environmental factor that shaped the assemblage in all ports were Total Polycyclic Aromatic Hydrocarbons, while Total Organic Carbon and the grain-size were less relevant. A co-occurrence analysis was applied for identifying which genera cohesively respond to site-specific environmental conditions in order to recalibrate and implement the sets of bioindicator genera in relation to their different opportunistic behaviour. Finally, we provided some suggestions for a proper application of the nematode indices (Maturity Index, Index of Trophic Diversity, Shannon diversity) in order to encourage the use of free-living nematodes for the environmental quality assessment of commercial ports.

Three new species of Microlaimus are described from the continental shelf of the Campos Basin, southwest Atlantic, Brazil. Microlaimus campiensis sp. n. differs from all other species in the presence of two anterior testes, slender spicules with enlarged proximal ends, 7-11 pre-cloacal papilliform supplements, and females with a pair of constriction structures, one on each branch of the ovary. Microlaimus alexandri sp. n. shows sexual dimorphism in the size of the amphidial fovea, which occupies 100% of the diameter of the corresponding area in the male; the buccal cavity provided with five teeth and a slightly cuticularized cuticular ring. Microlaimus vitorius sp. n. has four longitudinal-lateral rows of glands associated with small pores, one seta and three pores small pre-cloacal, and the gubernaculum has a triangular base. An amendment to the diagnosis of the genus is proposed, where the number of teeth was modified.

Piipironus grandis gen. et sp. nov. is described from Piip submarine volcano, the Bering Sea. Piipironus gen. nov. shows all main characters of Thalassironinae but differs from all known ironids in the form of the amphid (spiral vs pocket-like) and the simultaneous presence of precloacal papilliform supplements and tubular postcloacal organs. Pared tubular postcloacal organs have never been described before for the family Ironidae. The combination of papilliform precloacal supplements and the pair of tubular postcloacal organs described for Piipironus grandis gen. et sp. nov. is unique among nematodes. The study of the nematofauna of the Piip submarine volcano began quite recently, and Piipironus is the second new genus of nematodes described from here from one sample of bottom sediments. This can be taken as one of the examples of the hyper-high diversity of marine nematodes.