Mar Environ Res. 2026 Jun 9;220:108190. doi: 10.1016/j.marenvres.2026.108190. Online ahead of print.
ABSTRACT
Abyssal and hadal macroinfaunal communities (>300 μm) were studied across a longitudinal geographic transect in the Southeast Pacific region (71°- 109°W). Composition, structure, and distribution were analyzed in relation to the seafloor organic content associated with surface productivity. Sediment samples were collected at each study site with a multicore containing eight cores of 7.5 cm internal diameter, covering associated seamounts, oceanic islands, and trench environments. Faunal composition was dominated by Crustacea, Mollusca, and Annelida, with Crustacea as the most diverse. Polychaeta and Copepoda were always the most common and abundant in all sites recording a relative abundance of 38% and 33%, respectively. Vertical distribution showed that 73% of fauna inhabit the first centimeter of sediment. The number of individuals was low and mean density per site was 710 ind. m-2, however the high number of species recorded only once would indicate a high diversity of species in the study zone. Ecological indices showed higher values in eutrophic and mesotrophic areas coinciding with the record of the highest concentrations of parameters related to sediment organic content. Differences between habitats were observed, recording higher abundance and diversity on Trench and Seamount sites from eutrophic and mesotrophic zones, while lower values of these descriptors on Seamount and Oceanic Island sites associated with less productive zones. Statistical analysis and correlations showed that Chloroplast Pigment Equivalent and Chlorophyll-a may explain the observed patterns for the benthic community. The macroinfaunal communities described are typical of abyssal and hadal sediment environments and they appear to respond to organic inputs according to recorded spatial distribution patterns.
PMID:42284669 | DOI:10.1016/j.marenvres.2026.108190