Data_Sheet_1.docx

Abstract

Sansha Bay (26.40°–27.00° N, 119.50°–120.20° E) is a typical semi-enclosed bay, located in northern Fujian Province, China, and adjacent to the East China Sea. The ichthyoplankton species composition and assemblage structure were investigated based on monthly sampling in 25 stations in April–September 2019, covering the important spring and summer spawning season in the region. The samplings were conducted in the first 35 days of the full moon or new moon phases using a standard plankton net through horizontal tows during daytime. Totally, 24,757 fish eggs and 692 fish larvae were collected. With a combination of external morphology and DNA barcoding analyses, the ichthyoplankton were classified into 61 taxa in 15 orders and 23 families, from pelagic to demersal and benthic species. The dominant order was the Gobiiformes, including 25 species (41.0%). The dominant taxa, in terms of relative abundance and frequency of occurrence, consisted of commercially important fishes, such as Setipinna tenuifilis (Engraulidae), Epinephelus akaara (Serraenidae), Collichthys lucidus and Nibea albiflora (Sciaenidae), and Acanthopagrus schlegelii and Pagrus major (Sparidae). Low-valued and small-sized fishes, such as Stolephorus commersonnii (Engraulidae), Solea ovata (Soleidae), and Nuchequula nuchalis and Photopectoralis bindus (Leiognathidae), were also dominant species. The ichthyoplankton was categorized into five different temporal assemblages based on cluster and non-metric multi-dimensional scaling (nMDS) analysis: April, May, June, July and August–September (ANOSIM, Global R = 0.656, p < 0.01) with the highest density and richness of ichthyoplankton occurred in May. The spatial distribution pattern showed that the high density of ichthyoplankton occurred mainly around Guanjingyang and along Dongchong Peninsula coastline into Dongwuyang, while low density mainly in the northwest waters of Sandu Island. Temperature, salinity and chlorophyll a were key factors structuring the ichthyoplankton assemblages in Sansha Bay. The results revealed that the ichthyoplankton composition and spatial distribution in Sansha Bay changed over the past three decades.