Search

This study evaluated the potential effect of stock enhancement on a coastal ecosystem. Based on data collected from the 2020 bottom trawl survey and literature information, an Ecopath model was constructed containing 19 functional groups representing the coastal area of southern Zhejiang, China. Jellyfish (Rhopilema esculenta) and black seabream Acanthopagrus schlegelii were selected as target-enhancing species based on their extensive juvenile release records. The maximum carrying capacity of these two species was estimated by static Ecopath and the potential ecological effects of enhancement activity for these two species were evaluated by the Ecosim routine. The trophic level (TL) of the functional groups in the coastal area of southern Zhejiang ecosystem ranged from 1 (primary producers) to 4.56 (sharks). The mean transfer efficiency of the coastal area ecosystem of southern Zhejiang was 8.71%, in which the relatively low transfer efficiency from TL2 to 3 was considered the main bottleneck that limited the biomass of higher TL species in this ecosystem. System characteristics indicated that the coastal area ecosystem of southern Zhejiang was vulnerable to disturbances and had low recovery ability. Enhancement simulation results indicated that the enhancement of jellyfish and black seabream had a partial impact on the functional groups of the ecosystem. Both jellyfish and black seabream enhancements adversely affected most groups of fish, cephalopods, and crabs, while jellyfish release stimulated the biomass of crabs. Ultimately, the present study indicates that the enhancement of black seabream decreased the total fish biomass via complex trophic interactions in the food web. Additionally, this study shows that recapture rates might not be sufficient to evaluate the net effect of stock enhancement, and therefore highlight the importance of ecosystem-based assessments for stock enhancement. [Display omitted] • Ecosystem-level effects of different stock enhancement strategies were analyzed. • An ecosystem model represents the southern Zhejiang coastal area, China, was constructed. • The enhancement of Jellyfish and Black seabream had partial impacts on the functional groups of this ecosystem. • Recapture rates might not be sufficient to evaluate the effect of stock enhancement. [ABSTRACT FROM AUTHOR]

This study investigated the feeding habits of black croaker (Atrobucca nibe) to fully understand its role in the food web in southern coastal waters of Zhejiang, China. In total, 225 black croakers were collected in a bottom trawl survey, of which 195 were used for the stomach contents analysis and 30 for high-throughput sequencing (HTS). Both approaches showed that the main prey was shrimp, with Alpheus japonicus being the most predominant. In addition, black croaker also fed on other benthic species, suggesting that it was a demersal predator. Feeding intensity also varied with black croaker body length, as did prey preference, from small-sized species to larger species with increases in fish size; in addition, prey species were more diverse in the large-bodied prey group. Canonical correspondence analysis indicated that the feeding habit of black croaker was most significantly correlated with temperature and dissolved oxygen. HTS was shown to be a feasible high precision semi-quantitative analytical approach, although it must be combined with morphological methods to obtain more complete feeding data; thus, it could provide an effective scientific basis for feeding ecology studies of marine organisms. • The feeding habits of common economic fish in China were analyzed. • A comprehensive analytical method combining stomach content analysis and high-throughput sequencing was applied. • The influence factors of feeding habits were analyzed as explanatory variables in canonical correspondence analysis. • The feasibility of applying high-throughput sequencing to the feeding habits analysis of black croaker was confirmed. [ABSTRACT FROM AUTHOR]