The effect of environmental factors on spatial-temporal variation of heterobranch sea slug community in northern Taiwan

Sea slug (Subclass Heterobranchia) biodiversity is an important element of marine coral reef communities. However, due to their small size and cryptic behavior, few studies have examined spatiotemporal variation. Taiwan in the middle East Asia Island Arcs, where it one hotspots sea diversity. Meanwhile, northeast coast this island lies within subtropical monsoon region, climate shifts from a warm southwest (SW: May Sep) cold (NE: Oct Apr). Between monsoons, distinct temperatures currents result different community structures. To understand how those environmental factors (i.e., season, diel period water depth) influence species richness assemblages, we surveyed these invertebrates monthly at both night day by diving protection area (CJ) nearby non-protected site (MR) 2020 Apr 2021. We showed that composition our sampling was highly consistent with what found Okinawa Pescadores island, but less similar southern or Hong Kong. On Taiwan, number abundance were higher CJ than MR, ( H’ ) evenness index J ’ lower MR. Additionally, cluster analysis indicated assemblages differed between two sites. Monsoon season significantly influenced during SW being NE also seasons. Moreover, increased depth (within range 0-25 m). Diel did not exert strong impact on biodiversity, except for CJ, night. Our study suggested changing seasons could transport individuals originating either north south arcs. Furthermore, temperature food sources may differ depths, thereby influencing region.