Nematode communities from a natural oil seep off Svalbard

Cold-seep sediments, where active fluid seepage rich is observed, have been associated with the presence of endemic nematode communities. Under the scope of the AKMA project, a seep site located offshore Svalbard was sampled for the first time to investigate the Nematoda assemblages associated with methane and crude oil seepage. Replicated samples were collected by means of the blade- and push-cores, on a bacterial mat where active gas and oil seepage was observed, as well as in sediments nearby without evident seepage activity, as reference. Sediments collected were used to characterize the community structure and diversity of the meiofauna taxa, particularly the nematode assemblages, as well as key environmental parameters (i.e, sediment and pore-water geochemistry, organic content, grain size). Preliminary observations showed no major differences in total meiofauna density between microhabitats, with a predominance of nematodes (>90%), followed by harpacticoid copepods and nauplii larvae, as typically seen in other deep-sea environments. However, an in-depth investigation into the nematode assemblages, revealed a low nematode diversity in the bacterial mats sediments, by comparison, to the reference. Bacterial mat-associated assemblages were predominantly composed of Halomonhystera sp.1 (39%), followed by a single Chromadoridae species (32%). Evidence of morphological and reproductive adaptations were observed in several of the species present and could be indicative of how these organisms are able to survive the toxic environmental conditions at this seep site, namely high concentrations of hydrogen sulphide and crude oil. These observations contribute to a large gap in the understanding of how infauna thrive in extreme environments in the Arctic

Nematode communities from a natural oil seep off Svalbard.

Cold seeps are considered hotspots of energy on the seafloor, establishing unique conditions for life to thrive. In chemosynthetic-based habitats such as these, sediments from active sites are typically inhabited by endemic nematode communities which tolerate the local reduced environmental conditions, but no studies have been carried out on seep sites so far north in the Arctic. Under the scope of the AKMA project, an oil seep site located offshore Svalbard was sampled for the first time to investigate the associated meiofauna assemblages with methane and crude oil seepage. Replicated samples were collected by means of the blade and push cores handled by the ROV Ægir6000, both on bacterial mats with evident gas and oil seepage, as well as in sediments nearby without evident seepage activity, as reference. Sediments collected were used to characterize the community structure and diversity of the meiofauna taxa, particularly the nematode assemblages, as well as key environmental parameters (i.e, sediment and porewater geochemistry, organic content, grain size). Preliminary observations showed no major differences in total meiofauna density between microhabitats, with a predominance of nematodes (>90%), followed by harpacticoid copepods and nauplii larvae, typically seen in other deep-sea environments. However, an in-depth investigation into the nematode assemblages revealed that bacterial mats hosted an extremely low diversity of nematode species, by comparison, to the reference locations. Bacterial mat-associated assemblages were predominantly composed of a single species, Dichromadora sp.1, followed by Halomonhystera cf. disjuncta and Linhomoidae sp. 1. Evidence of morphological and reproductive adaptations in the species present seems to allow them to survive in this toxic environment, namely due to high concentrations of hydrogen sulfide and oil presence. The findings resulting from this study contribute to a large gap in the understanding of how infauna thrive in extreme environments with the presence of hydrocarbons in the Arcti

Evaluating environmental drivers of spatial variability in free-living nematode assemblages along the Portuguese margin

Understanding processes responsible for shaping biodiversity patterns on continental margins is an important requirement for comprehending anthropogenic impacts in these environments and further management of biodiversity. Continental margins perform crucial functions linked to key ecological processes which are mainly structured by surface primary productivity and particulate organic matter flux to the seafloor, but also by heterogeneity in seafloor characteristics. However, to what extent these processes control local and regional biodiversity remains unclear. In this study, two isobathic parallel transects located at the shelf break (300-400 m) and upper slope (1000 m) of the western Iberian margin were used to test how food input and sediment heterogeneity affect nematode diversity independently from the spatial factors geographical distance and water depth. We also examined the potential role of connectedness between both depth transects through molecular phylogenetic analyses. Regional generic diversity and turnover were investigated at three levels: within a station, between stations from the same depth transect, and between transects. High variability in food availability and high sediment heterogeneity at the shelf-break transect were directly linked to high diversity within stations and higher variation in community structure across stations compared to the upper slope transect. Contrastingly, environmental factors (food availability and sediment) did not vary significantly between stations located at the upper slope, and this lack of differences were also reflected in a low community turnover between these deeper stations. Finally, differences in nematode communities between both transects were more pronounced than differences within each of the isobathic transects, but these changes were paralleled by the previously mentioned environmental changes. These results suggest that changes in community structure are mainly dictated by environmental factors rather than spatial differences at the western Iberian margin. Furthermore, phylogenetic relationships revealed no evidence for depth-endemic lineages, indicating regular species interchanges across different depths

Characterization of collagen and fatty acid composition of “Carne Mirandesa-PDO” veal

The objective of this study was to evaluate chemical parameters related to meat quality, contributing to a better characterization of “Carne Mirandesa-PDO” veal. This study was made in three farms, from the Northeast region of Portugal (PG, FA1 and FA2), where calves were raised permanently indoors, nurse from their dams overnight, and fed with hay and concentrate made with local ingredients and soybean meal. Twenty five calves were slaughtered at 7 months old. Twenty four hours after slaughter, samples were collected from four different muscles: longissimus dorsi (LD), semimembranosus (SM), gluteus biceps femoris (GB) and triceps brachii caput longum (TBL), vacuum packaged and freeze-dried. Determinations of crude protein (CP), ether extract (EE), collagen and fatty acid were made. Collagen, CP and EE were significantly (p<0.001) affected by muscle type. Fatty acid composition was mostly affected by farm and by muscle type. The SM muscle was poor in saturated fatty acids (14:0, 15:0, 16:0, 17:0 and 18:0) and richer in polyunsaturated fatty acids than the other muscles. The ratio between n-3 and n-6 PUFA observed in this study are close to the usually found for pasture fed animals indicating the healthy value of “Carne-Mirandesa PDO” veal