Fish community diversity analyses in the Yangtze River estuary, China

Abstract

Background. Repetitive species-specific sound enables the identification of the presence and behavior of soniferous species by acoustic means. Passive acoustic monitoring has been widely applied to monitor the spatial and temporal occurrence and behavior of calling species. Methods. Underwater biological sounds in the Pearl River Estuary, China, were collected using passive acoustic monitoring, with special attention paid to fish sounds. A total of 1408 suspected fish calls comprising 18,942 pulses were qualitatively analyzed using a customized acoustic analysis routine. Results. We identified a diversity of 66 types of fish sounds. In addition to single pulse, the sounds tended to have a pulse train structure. The pulses were characterized by an approximate 8 ms duration, with a peak frequency from 500 to 2600 Hz and a majority of the energy below 4000 Hz. The median inter-pulsepeak interval (IPPI) of most call types was 9 or 10 ms. Most call types with median IPPIs of 9 ms and 10 ms were observed at times that were exclusive from each other, suggesting that they might be produced by different species. According to the literature, the two section signal types of 1+1 and 1+N 10 might belong to big-snout croaker (Johnius macrorhynus), and 1+N 19 might be produced by Belanger's croaker (J. belangerii). Discussion. Categorization of the baseline ambient biological sound is an important first step in mapping the spatial and temporal patterns of soniferous fishes. The next step is the identification of the species producing each sound. The distribution pattern of soniferous fishes will be helpful for the protection and management of local fishery resources and in marine environmental impact assessment. Since the local vulnerable Indo-Pacific humpback dolphin (Sousa chinensis) mainly preys on soniferous fishes, the fine-scale distribution pattern of soniferous fishes can aid in the conservation of this species. Additionally, prey and predator relationships can be observed when a database of species-PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.3301v1 | CC BY 4.0 Open Access | rec

Environmental influences on the spatio‐temporal distribution of Coilia nasus in the Yangtze River estuary

“…In this study, the effect of salinity on the distribution of Coilia nasus was similar acorss the three models. It has been suggested in some studies that salinity differences in the YRE are not observable among seasons, but there is a significant difference in the salinity from the interior to exterior estuarine regions observed year‐round (Shi, Chao, Quan, Huang, & Shen, 2012). This may be the reason why the response of salinity to abundance of Coilia nasus present a multimodal pattern (Figures 3c, 4d and 6d).…”

Seasonal and Spatial Variations in Fish Assemblage in the Yangtze Estuary and Adjacent Waters and Their Relationship with Environmental Factors

“…Of the 12 dominant species of fish, 8 species (Setipinna taty, Coilia mystus, Pampus argenteus, Trichiurus lepturus, Larimichthys polyactis, Harpadon nehereus, Chelidonichthys kumu, and Muraenesox cinereus) had seasonal migratory habits [6]. Overwintering migrations of species reduce their regional abundance and biomass [30]. For example, Harpadon nehereus is a warm-water fish that is intolerant of winter low water temperatures adjacent to the Yangtze Estuary [31]; this species is dominant in spring, summer, and autumn but not winter.…”

“…Most studies on fish in the Yangtze Estuary had focused on species composition, biodiversity, and fishery resources [8][9][10]. Only a small number of studies had reported interannual and spatial differences in fish assemblage structure adjacent to the Yangtze Estuary and how these are related to environmental factors [3,[11][12][13]. There is a lack of seasonal and spatial variation studies of fish assemblages in recent years.…”