SPATIO-TEMPORAL NICHE CHARACTERISTICS AND INFLUENCING FACTORS OF MAJOR NEKTON SPECIES IN MINNAN FISHING GROUND

The spatio-temporal ecological niche characteristics and influencing factors of major nekton species was determined by the relative importance, aggregation intensity, niche width, niche overlap and redundancy analysis based on data from four voyage fixed bottom trawl surveys in October 2019 (autumn), December 2019 (winter), April 2020 (spring) and August 2021 (summer). The results of the study showed that: (1) 214 species of nekton were identified in the surveyed sea area, with 18 dominant species. There is an obvious seasonal turnover of dominant species, with higher aggregation intensity of dominant species in summer and lower in spring. (2) In the temporal dimension, Metapenaeposis barbata had the largest ecotone width (0.99); the niche overlap of seven groups was equal to 1.00; in the spatial dimension, the niche width of Trachurus japonicus was the largest (2.57); the spatial niche overlap value of major nekton species exceeding 0.6 accounted for 71.3%; in the spatio-temporal dimension, Trachurus japonicus had the largest niche width (2.45) and Leiognathus ruconius Hamilton had the largest spatio-temporal niche overlap width (0.94) with Thrissa kammalensis Bleeker. (3) The redundancy analysis showed that bottom temperature and bottom salinity were the key factors affecting the spatio-temporal niche characteristics of the major nekton species in Minnan Fishing Ground.