Understanding the Spatial and Temporal Distribution and Environmental Characteristics of Polychaete Assemblages in the Coastal Waters of Ulleungdo, East Sea of Korea

Sang-Lyeol Kim,Ok-Hwan Yu

doi:10.3390/jmse9111310

Abstract

The coastal area of Ulleungdo in the East Sea has experienced large climate and environmental changes. However, research on marine benthic animals in this area has been very limited. In the present study, we investigated the spatial and temporal distribution of benthic polychaetes to determine their seasonal adaptability to environmental changes in the coastal waters of Ulleungdo in 2019. In total, 116 species (34 families) of polychaetes were identified with an average of 25 species per site. The average density was 772.8 individuals m−2, with the highest density in August and the lowest in February. The dominant species were Pseudobranchiomma zebuensis (15.6%), Scolelepis sp. (8.6%), Haplosyllis spongiphila (7.3%), and Lumbrineris nipponica (6.3%). The main factors affecting polychaete community structure were water depth and sediment type (gravel, sand, silt, clay). Based on cluster analysis, the polychaetes tended to group mainly in winter and summer with P. zebuensis and Syllis sp. contributing to the grouping. The dominant species was the suspension feeder, which correlated highly with habitat sediment type and was substantially consistent with the coast of Dokdo. Some species overlapped in the East Sea coast, but the number and diversity of species were higher in Ulleungdo. Our study results confirm the ecological characteristics of benthic polychaetes of Ulleungdo and provide information for future monitoring of the environmental and biological changes in the East Sea.

Highlights

The East Sea is the sea between Korea and Japan in the Northwest Pacific Ocean and is a microcosm of a large ocean system model due to its very dynamic marine biogeographic boundaries [1,2,3]
The marine volcanic island Ulleungdo is located in the center of the East Sea and has a steep coastline [11]
Dokdo is close to Ulleungdo and the two regions are very similar in habitat types and various benthic organisms [15,16]

Summary

Introduction

The East Sea is the sea between Korea and Japan in the Northwest Pacific Ocean and is a microcosm of a large ocean system model due to its very dynamic marine biogeographic boundaries [1,2,3]. The Tsushima Warm Current and the Liman Cold Current are important for the subtropical and subarctic circulations in the North Pacific and the East Sea, forming a polar front at approximately 40◦ N [4]. The coastal area of the central and northern part of the East Sea shows high productivity due to these currents [5]. The marine volcanic island Ulleungdo is located in the center of the East Sea and has a steep coastline [11]. The predominant surface current on Ulleungdo is the Tsushima Warm Current [13]. This current in the East China Sea flows into the East Sea through the Korea/Tsushima Strait [14]. Adherent benthic organisms with less seasonality reflect the biological characteristics of the sea area [17]

Methods

Results

Conclusion