Meiofauna and Nematode abundance from the West Florida Escarpment, NOAA Hydrosmac project

Study Extent

Sediment samples were taken during the RV Point Sur expedition to the West Florida Slope and Escarpment, Eastern Gulf of Mexico (PS20-8, U. Southern Mississippi/LUMCON; IMO WSC2276) October 1-18, 2019.

Sampling

Samples were taken using an Ocean Instruments MC800 multicorer and ROV push cores (USGS loan, operated by ROV Global Explorer). Sixty samples were completely processed for meiofauna higher taxa and nematode genus identification using morphological taxonomy, following standard scientific meiofauna protocols (32 – 500 micrometer) and the latest taxonomic literature. Samples contained 0-5 surface sediment from all relevant stations (1473-2267 m water depth range). A total of 20,927 individuals were identified to higher meiofauna taxon level (50% of the total yield was subsampled). Of these, 5,128 nematodes were identified to genus level. Twenty-two meiofauna groups were recognized. A total of 129 nematode genera were identified. Buffered formalin (10 % = 4% formaldehyde) sediment samples were used to extract the meiofauna using standard procedures (Heip et al., 1985; 32–500 μm sieves, LUDOX HS as centrifugation medium) to separate the organisms from the sediment particles. Fifty percent of all meiofauna were counted and between 100 and 150 nematode individuals were picked out randomly from each sample, transferred to anhydrous glycerol (Seinhorst, 1959) and mounted on slides. Meiofauna specimen preservation method: Buffered formalin (10%), stained with Rose Bengal Nematode Specimen preservation method: Buffered formalin (10%), stained with Rose Bengal, and mounted on glass slides with anhydrous glycerol

Quality Control

All meiofauna were identified under a stereoscopic microscope (50x magnification), and nematodes were identified under a compound microscope (1000× magnification) to genus level using Platt and Warwick (1988), the latest taxonomic literature, and the NeMys nematode database and identification keys (nemys.ugent.be; linked to World Register of Marine Species). Specimens that could not be identified to the genus level were assigned to the appropriate higher taxon level.

Method steps

1. See sampling description and quality control fields.

Meiofauna (>32um) identified to higher taxon level (phylum), and Free-living Nematoda (nematodes, roundworms) identified to genus level.

1. Arthropoda
   rank: phylum
2. Nematoda
   rank: phylum
3. Annelida
   rank: phylum
4. Platyhelminthes
   rank: phylum
5. Ciliophora
   rank: phylum
6. Loricifera
   rank: phylum
7. Kinorhyncha
   rank: phylum
8. Priapulida
   rank: phylum
9. Nemertea
   rank: phylum
10. Tardigrada
    rank: phylum
11. Gastrotricha
    rank: phylum
12. Cnidaria
    rank: phylum

West Florida Slope and Escarpment, Eastern Gulf of Mexico