Do meio- and macrobenthic nematodes differ in community composition and body weight trends with depth?

Area of Science:

• Marine Biology
• Deep-Sea Ecology
• Benthic Ecology

Background:

• Nematodes are typically classified as meiobenthos, organisms found in smaller sediment fractions.
• This study investigates nematode communities in both macrobenthic (>250/300 µm) and meiobenthic (<45 µm) samples.

Observation:

• Nematode dry weight per individual increased with water depth in macrobenthic samples from the Arctic and Gulf of Mexico.
• Conversely, meiobenthic nematodes in the Gulf of Mexico showed a decreasing weight trend with depth.
• Macrobenthic nematode communities in the Gulf of Mexico were more similar to those in the Canada Basin than to Gulf of Mexico meiobenthic nematodes.

Findings:

• Dominant genera in macrobenthos (Enoploides, Crenopharynx, Micoletzkyia, Phanodermella) drove community differences.
• Non-selective deposit feeders decreased in relative abundance with depth in macrobenthos.
• A distinct assemblage of larger, heavier nematodes exists within the macrobenthos.

Implications:

• The presence of substantial macrobenthic nematodes necessitates their inclusion in future macrobenthic ecological studies.
• Current classifications may underestimate the ecological role of nematodes in deep-sea environments.
• Understanding nematode size and weight trends with depth provides insights into deep-sea food webs and biogeochemical cycling.