Morphometric, taxonomic, and functional trait data of deep-sea nematodes from a colonisation experiment simulating organic matter deposition at HAUSGARTEN (Fram Strait)

This dataset contains individual-based morphometric, taxonomic, and functional trait data of deep-sea nematodes collected during a colonisation experiment conducted at the long-term observatory HAUSGARTEN in the Fram Strait (Arctic Ocean). The experiment aimed to investigate the colonisation dynamics and trait-based responses of nematode communities to different qualities of organic matter input in artificially prepared deep-sea sediments.

During the RV Polarstern expedition PS85 (June 2014), a bottom lander was deployed at 1265 m water depth near HAUSGARTEN station HG-I (79°8.69'N, 6°8.23'E). The lander carried twelve colonisation cores filled with azoic, artificial sediments and exposed for three months on the seafloor. Three treatments were applied, each with four replicate cores: (1) enrichment with fresh Phaeocystis (FP), (2) enrichment with decayed Phaeocystis (DP), and (3) unenriched control cores. This design simulated the effect of phytodetritus deposition in different degradation states on early colonisers within benthic communities.

As a natural reference, sediment samples were taken from undisturbed seafloor using a multiple corer (MUC) at 1244 m depth at the same station (79°8.01'N, 6°6.39'E). For both the artificial colonisation cores and natural MUC samples, subsampling was conducted using 2.2 cm diameter cut-off syringes. From each core, the upper 3 cm of sediment were collected, sliced into 1 cm layers, and fixed in 4% borax-buffered formalin prepared with filtered seawater.

Individual nematodes were identified to genus level. Body length and width were measured, and biomass (µg dry weight) was calculated. Each genus was assigned a feeding type based on Wieser (1953) and a coloniser–persister (c–p) value following Bongers (1990) and Bongers et al. (1995), providing insight into their trophic role and life-history strategy.

This dataset enables comparative analysis of nematode traits under controlled experimental enrichment versus natural background conditions, and contributes to a better understanding of benthic ecosystem responses to variable organic matter input in Arctic deep-sea environments.