Initial recovery of fish faunas following the implementation of pen-culture and fishing bans in floodplain lakes along the Yangtze River.

Given the decline of natural fish abundance and diversity, a ban on pen-culture and fishing has been imposed on floodplain lakes along the Yangtze River. In order to examine the recovery efficiency of fish faunas, we compared the changes in multidimensional (α and ß) diversity in the Shengjin Lake between pen-culture stage (PS) and recovery stage (RS). Our results demonstrated significant variations in fish community composition, with distinct populational restoration in wild species of high trophic level and river-lake migratory species. The higher abundance of wild and migratory species in RS implied the enhanced dispersal and exchange process of fish individuals with the elimination of net pens. Despite significant variations of community composition, the α and ß diversity indices exhibited non-significant change between PS and RS. However, our study still revealed the recovery of natural seasonal community dynamics, since there were significant variations of both α and ß diversity between high-water (HW) and low-water (LW) seasons in RS. The significant higher α diversity (S, d, H') in HW indicated flooding induced fish supplements in floodplain lakes, due to the well-developed breeding sites, nurseries and refuges provided by floodplain lakes. Meanwhile, the significant lower ßSOR and ßSIM in HW implied the homogenized communities during flooding seasons, which can be ascribed to better hydrological connectivity of various habitats and more even distribution of fish faunas triggered by flood pulses. The reappearance of natural seasonal variations in multidimensional (α and ß) diversity indicate the initial recovery of fish faunas. There is a pressing need for prolonged surveillance to explore the recovery mechanism of fish assemblage. Meanwhile, our results also highlight the importance of conserving the lacustrine connectivity and seasonal flooding for the recovery of fishery resources in the floodplain lakes.

Microplastic contamination assessment in water and economic fishes in different trophic guilds from an urban water supply reservoir after flooding.

Rain and floods events are responsible for the transport of microplastics in freshwater ecosystems, yet to date, rare study has examined microplastics pollution in urban water supply reservoirs during such events. In this study, we investigated the concentrations and characteristics of microplastic in water and economic fish species with different feeding guilds in the Dafangying Reservoir, an important source of drinking water for Hefei city. Microplastic concentrations in water were relatively higher than that in natural lakes, indicating abundant microplastic contaminants input through overland runoff triggered by flooding. Our results detected five types (fiber, debris, film, microbead and particle) and six colors (black, transparent, blue, yellow, red and green) of microplastics in water samples. Fiber accounted for the dominant shape, which may result from the household sewage from washing clothes and desquamated fiber transported by wind and overland runoff. Meanwhile, transparent was the predominant microplastic color, which can be ascribe to the widely use of intentionally manufactured transparent disposable plastic commodities in cities. Then in fish samples, the microplastic concentrations ranged from 8.75 to 51.3 items/individual in fish guts, and 9.5-52.6 items/individual in fish gills. Our results demonstrated significant higher microplastic concentrations in planktivorous and herbivorous species. The filter feeding capture mode, i.e., engulfing floating prey through frequently drawing in large volume of water confused with microplastics, may result in the higher microplastic concentrations of planktivorous fishes. Due to the dense microplastics adhering on plant surface, herbivorous fishes can concentrate higher microplastics abundance through the ingestion of macrophytes. According to the biological concentration factor (BCF), all the determined microplastics gave BCF far below 1, suggesting the low bioaccumulation capacity of microplastics in fish species.

Metal concentrations and risk assessment in water, sediment and economic fish species with various habitat preferences and trophic guilds from Lake Caizi, Southeast China.

Despite the potential emissions of heavy metal pollution in Lake Caizi due to extensive agriculture, urban growth and fishing activities, the risk posed by metal concentrations to aquatic environments and human populations has not yet been studied. In this study we compared the concentrations of Hg, As, Pb, Cd, Cr, Cu and Zn in water, sediment, and economic fish species with different habitat preferences and trophic guilds across important fishery areas in Lake Caizi, located on the northern shore of the Yangtze River, Southeast China. The concentrations of Cr in water were found approximately 6 times higher than the safety thresholds established by international legislation. Cr, Zn, As and Cd concentrations in sediments surpassed the background values for Yangtze River basin in Anhui Province. However, all the studied fish species in Lake Caizi had metal concentrations lower than legislation thresholds established by China and international organizations. Heavy metal concentrations were found to be significantly higher in demersal (inhabiting near the sediments) and piscivorous (possessing higher trophic level) fishes than in pelagic/benthopelagic (inhabiting the upper and lower water column) and herbivorous/planktivorous (possessing lower trophic level) fishes. Our finding demonstrated that the metal concentrations in fishes are simultaneously influenced by the habitat and bio-accumulation through the food chain. According to target hazard quotient (THQ) calculations for heavy metal contents in the muscles of fish species, all the determined heavy metals gave THQ values lower than 1, suggesting the inexistence of health risks from the intake of fishes from Lake Caizi.

Molecular evidence for taxonomic status of the gudgeon genus Huigobio Fang, 1938 (Teleostei: Cypriniformes), with a description of a new species from Guangdong Province, South China.

The gudgeon cyprinid genus Huigobio Fang, 1938 is re-diagnosed. It can be distinguished from all other genera of Armatogobionina Kryzhanovsky, 1947 and the Gobioninae by its uniquely modified lower lip. The lower lip has a small, heart-shaped, longitudinally non-bisected central pad and two lateral lobes expanded as a wing-shaped flap completely covered with papillae. The lobes contact each other posteromedially, but are not completely confluent. Huigobio exilicauda, new species, is described from the Zhu-Jiang drainage of Guangdong Province, South China. It differs from H. chenhsienensis in caudal-peduncle thickness and interorbital width.

Accumulation of microplastics in fish guts and gills from a large natural lake: Selective or non-selective?

In recent years, microplastics (MPs) have become emerging contaminant causing widespread concern about their ecotoxicological effects. However, little is known regarding the accumulation of MPs in different tissues of fishes, especially for freshwater fishes in natural environments. In this study, MPs in guts and gills of 11 fish species from Lake Chao, China were examined to explore the accumulation differences and foraging preferences of MPs. In general, MPs in fish guts varied from 2.85 to 8.38 items/individual, while ranged from 3.06 to 8.90 items/individual in fish gills. In terms of characteristic composition (shape, color, size, and polymer type), our results demonstrate higher occurrence of fibrous, black, small sized (<1 mm), and polypropylene MPs. Meanwhile, MPs concentrations in fish guts differed significantly among various feeding groups, with none significant difference detected in fish gills. In addition, fish guts exhibit more distinct foraging preferences for specific featured MPs in contrast with fish gills. These results indicate selective MPs accumulation in fish guts whereas random MPs accumulation in fish gills. Fish gills, adhering MPs by non-selective water exchange, may be more related to the real-time MPs abundance in water. To some extent, fish gills may be employed as important instruments to reflect MPs contamination in aquatic environments. Influenced by diverse feeding behaviors such as visual cues and sensory systems, MPs accumulation in fish guts reflect intrinsic differences, thus making fish guts sensitive organ in monitoring MPs' ecological risk for their health.

Seasonal variation and ecological risk assessment of microplastics ingested by economic fishes in Lake Chaohu, China.

Microplastic (MP) contaminations in freshwater organisms have attracted substantial attention worldwide. However, seasonal field studies of MPs concentrations in aquatic life are scarce. In this study, we analyzed the seasonal variation and ecological risk of MPs concentrations in economic fish species from Lake Chaohu in China between wet and dry seasons. Within both seasons, MPs in fish were systematically analyzed using methods of KOH digestion, NaCl density floatation and raman spectroscopy. MPs abundance in economic fishes were significantly higher in dry season than that in wet season, which can be ascribed to the MPs' amplification effects in lacustrine ecosystems during dry season. Whereas, our results recorded similar and homogenized characteristic composition of MPs in economic fishes between wet and dry seasons. In both seasons, fiber was the main morphological type, black and blue were the most common MPs color, and MPs ranging from <0.5 mm accounting for the most abundant size. In addition, polypropylene (PP) and polyethylene terephthalate (PET) accounted for the most abundant polymer type detected by economic fishes in both seasons. In terms of feeding groups and habitat preferences, planktivorous and pelagic fish species exhibited sensitive variations of MPs concentrations between wet and dry seasons, thus being highlighted as good bioindicators of MPs contaminants in freshwater ecosystems. Our results revealed higher ecological risks of MPs in wet season than that in dry season when indicating from polymer risk index (H). By providing detailed and direct toxicity information, our study highlights the usage of polymer risk index for ecological risk assessment in aquatic organisms.

Occurrence and bioaccumulation of sulfonamide antibiotics in different fish species from Hangbu-Fengle River, Southeast China.

As a class of synthetic sulfur drugs, sulfonamides (SAs) have been used to treat diseases and promote organism growth. Different concentrations of SAs have been detected in the water environment, which has threatened the ecological environment. In this study, the contamination of 9 SAs in water, sediments, and 8 fish species from the Hangbu-Fengle River, China, were analyzed using UPLC-MS/MS. The total SA concentrations in surface water, sediments, and fish were ND-5.064 ng/L, ND-5.052 ng/g dry weight (d.w.), and ND-1.42 ng/g wet weight (w.w.), respectively. The major compounds were sulfadiazine (SDZ), sulfamerazine (SMZ), and sulfamethoxazole (SMX) in water and fish. The SA levels of in fish from different habitat preferences revealed a spatial difference, with the order of demersal species > pelagic species. Moreover, the SA concentrations were affected by trophic guilds, indicating their decrease in the order of piscivorous fish > omnivorous fish > planktivorous fish > herbivorous fish. The obtained bioaccumulation factors showed that SMZ and SMX have strong bioenrichments in Ophiocephalus argus Cantor and Pelteobagrus fulvidraco. The risk assessment indicated that SAs did not pose significant health threats to the organisms. This research is the first report of SA contamination in the Hangbu-Fenle River, which can provide an important scientific basis for their pollution prevention and ecological risk assessment in the aquatic environment.

Multifaceted biodiversity measurements reveal incongruent conservation priorities for rivers in the upper reach and lakes in the middle-lower reach of the largest river-floodplain ecosystem in China.

Biological conservation necessitates robust understanding of multifaceted biodiversity from local to regional scales. Mismatches among multifaceted diversity and conservation trade-offs are the most important challenge for conservation planning. The Yangtze River floodplain is among the most speciose whereas threatened and poorly protected ecosystems in China. Here we evaluated multifaceted (taxonomic, phylogenetic, and functional) alpha and beta fish diversity by simultaneously addressing two typical habitats (FRs, floodplain rivers and FLs, floodplain lakes) in this basin, to reliably aid conservation planning across local and regional scales. Our results demonstrated spatially incongruent multifaceted fish diversity between FRs and FLs. Characterizing by flocks of phylogenetic close species, we detected significantly higher species richness while lower phylogenetic and functional alpha diversity in FRs. In contrast, fish assemblages in FLs exhibited significantly higher functional alpha diversity characterized by functional unique species. Consequently, conservation planning should fasten on clusters of phylogenetic close endemic species to sustain high intrinsic species richness in FRs, and sustain high functional diversity as well as protecting fish species with unique functions in FLs. Meanwhile, for all the taxonomic, phylogenetic, and functional facets, our results demonstrated significantly higher turnover components in FRs, and the dominant contribution of the nestedness components to overall beta diversity in FLs. As a result, conservation planning in FLs may just focus on several richest lakes, while multiple spatially disjunct river networks should be protected in FRs. Contradicting the anthropocentric "new conservation", our study advocated protecting intrinsic uniqueness and peculiarity of multifaceted biodiversity as well as the ecological integrity.

Re-description of the gudgeon species Saurogobio gracilicaudatus Yao & Yang in Luo, Yue & Chen, 1977 (Teleostei: Cyprinidae) from the Chang-Jiang basin, South China, with a note on its generic classification.

Saurogobio gracilicaudatus, originally described from the middle Yangtze River (Chang-Jiang in Chinese) basin at Yichang and Guanghua (now Laohekou), Hubei Province, South China, is here re-described, with particular concern for oromandibular structures in the mouth. It is uniquely distinguishable from all other species of Saurogobio in having a rostral cap with a slightly crenulated median portion, lips covered with brush-like, conical papillae, and a lower lip with a small, smooth and protruded central pad anteriorly free and posteriorly confluent with lateral lobes. The generic classification of this species is also discussed on the basis of oromandibular structures, which are of taxonomic importance in generic classification of gudgeons.