Abstract
Sediment samples were collected from 23 sites near the Yap Trench in the Western Pacific Ocean with a depth range of 2896 m to 7837 m. The assemblage composition, spatial distribution, and relationship with environmental variables of meiofauna were studied. A total of 17 meiofaunal taxa were identified, including free-living marine nematodes, benthic copepods, nauplii, ostracods, halacarids, kinorhynchs, cumaceans, turbellarians, cladocerans, polychaetes, oligochaetes, isopods, tanaidaceans, amphipods, tardigrades, gastrotrichs, and pycnogonids. The average abundance of meiofauna was (172.88±149.02) ind·10cm-2. Marine nematodes were the most abundant group, with an average abundance of (120.26±102.85) ind·10cm-2, accounting for 69.97% of the total meiofauna, followed by benthic copepods (36.13±48.72) ind·10cm-2, accounting for 21.04%. The horizontal distribution of meiofauna showed that the high values of meiofaunal abundance were mainly distributed in the northwestern part of the study area and correlated with high sediment organic matter content, which possibly was related to the localized topography, food sources, and hydrodynamics within this area. Vertical distribution showed that meiofauna were mainly distributed in the upper and middle sediment layer (0-6cm). Results of BIOENV showed that sediment median diameter and phaeophorbide content were the most important factors affecting meiofauna community structure. This study provides an insight into relationships of deep-sea meiofauna assemblages with environmental factors in the Western Pacific Ocean.
Highlights
Meiofauna represents a group of small-sized benthic animals that pass a mesh screen with an aperture of 0.5 mm, but are retained by a mesh screen with an aperture of 0.031 mm (Thiel, 1971)
This study explored the composition, abundance of meiofauna, and sediment characteristics in the adjacent waters of the Yap trench, including the West Caroline basin, and measured sediment organic matter content, grain size, chlorophyll, and pheophorbide (Pha) contents
Through analysis of the relationship between these environmental factors with the abundance and assemblages of meiofauna, the present study aims to explore whether any of these environmental variables drives the meiofauna assemblages and how these compare to depth differences, and whether the topography of the deep-sea floor affects meiofauna distribution
Summary
Meiofauna represents a group of small-sized benthic animals that pass a mesh screen with an aperture of 0.5 mm (or 1.0 mm), but are retained by a mesh screen with an aperture of 0.031 mm (Thiel, 1971). Distribution Patterns of Deep Sea Meiofauna widely distributed meiofauna taxa which show a high turnover rate, and are food sources for larvae of fishes, shrimps, and shellfish. They play an important role in energy conversion and as indicators for environmental health. Meiofauna activities modify a series of physical, chemical, and biological sediment properties. These changes, directly or indirectly, positively or negatively, affect a variety of ecosystem services, including sediment stabilization, biogeochemical cycles, waste removal, and food web dynamics, at different spatial and temporal scales. Small animals can regulate ecosystem processes in sediment with few or no large animals, thereby improving the resilience of benthic ecosystem processes that are essential for the continued provision of ecosystem services (Schratzberger and Ingels, 2018)
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