2026-10-15T02:10:21Z https://www.scidb.cn/oai

10.57760/sciencedb.cjae.0009d 2026-08-20T15:12:09Z

2026-08-20 Paper dataset-2026-0530-Trophic niche of four common fish species in Hongze Lake and Gaoyou Lake under different hydrological regulation doi:10.57760/sciencedb.cjae.0009d en This dataset was generated to support the study on trophic niche patterns of four common fish species in Hongze Lake and Gaoyou Lake under contrasting water-level regulation backgrounds. Field sampling was conducted in May and November 2023, representing the end of the relatively stable water-level period and the end of the highly fluctuating water-level period, respectively. A total of 357 fish samples were collected, including Parabramis pekinensis, Carassius auratus, Toxabramis swinhonis, and Coilia brachygnathus. In each lake, 12 sampling sites were established to cover the major habitat types, including open-water areas, river inflows, lake outlets, and littoral zones. Therefore, the temporal resolution of the dataset consists of two discrete sampling campaigns in 2023, whereas the spatial resolution is represented by individual sampling sites distributed across the two lakes. The raw fish data are recorded at the individual-sample level, allowing each observation to be linked to lake, sampling period, species, and sampling site.For stable isotope analysis, approximately 2–3 g of dorsal white muscle was collected from each fish specimen. Samples were rinsed with deionized water, dried, ground into a homogeneous powder, and weighed into tin capsules. Carbon and nitrogen stable isotope ratios (δ¹³C and δ¹⁵N) were measured using a Delta V Advantage isotope ratio mass spectrometer (Thermo Fisher Scientific, Germany). International reference materials IAEA-USGS40 and IAEA-USGS41 were used for calibration. Stable isotope values are expressed in per mil (‰). The δ¹³C values were used mainly to characterize differences in basal carbon-source use, whereas δ¹⁵N values were used together with baseline organisms to estimate fish trophic position. Baseline isotope data from bivalves and zooplankton were used in the Bayesian trophic-position model.All statistical analyses were conducted in R. Fish trophic positions were estimated using the tRophicPosition package with a two-baseline Bayesian model. The nitrogen trophic discrimination factor was set to ΔN = 3.4‰, the carbon discrimination factor to ΔC = 0.39‰, and the trophic position of baseline organisms to λ = 2. Isotopic niche width was quantified using the SIBER package. Both the small-sample-size corrected standard ellipse area (SEAc) and Bayesian standard ellipse area (SEAb) were calculated, with SEAb posterior summaries and credible intervals used to describe uncertainty in niche-width estimates. Directional niche overlap probabilities were estimated using the nicheROVER package based on a 95% core niche region. Because niche overlap is directional, the probability that the niche region of species A is contained within that of species B is not necessarily equal to the reverse probability. The overall δ¹³C–δ¹⁵N composition was additionally evaluated using permutational multivariate analysis of variance based on Euclidean distances.The submitted dataset contains both individual-level stable isotope observations and derived analytical results that directly support the conclusions of the associated article. The raw fish isotope table contains 357 individual fish records, with columns describing sample identification, lake, sampling period, sampling site, species, δ¹³C, and δ¹⁵N; body length and body weight may also be retained where available. The baseline isotope table contains the corresponding δ¹³C and δ¹⁵N measurements of bivalves and zooplankton used in trophic-position estimation. The trophic-position results are summarized by lake, sampling period, and fish species, yielding 16 lake × period × species groups. The isotopic niche-width dataset similarly contains SEAc and SEAb estimates for these 16 groups, together with posterior statistics and credible intervals where available. The directional niche-overlap dataset contains pairwise overlap probabilities among the four fish species for each lake and sampling period. With four species, each lake-period combination contains 12 directional interspecific comparisons excluding self-comparisons, resulting in 48 directional overlap comparisons across the four lake-period combinations.The dataset is organized into several interoperable files, including 01_Fish_stable_isotope_raw_data.csv for individual fish isotope measurements, 02_Baseline_stable_isotope_raw_data.csv for baseline organisms, 03_Trophic_position_results.csv for Bayesian trophic-position estimates, 04_Isotopic_niche_area_results.csv for SEAc and SEAb results, 05_Directional_niche_overlap_results.csv for niche-overlap probabilities, and 06_PERMANOVA_results.csv for multivariate statistical results. The accompanying 07_Analysis_code.R file contains the principal R code used for data analysis and reproduction of the major results. All tabular files are provided in CSV format and are recommended to be encoded in UTF-8. Variable names are provided in English, and measurement units are specified either in the column names or in the accompanying README file.No intentional missing values are used to represent measured isotope observations in the analysis-ready dataset. In directional niche-overlap matrices, NA values on the main diagonal indicate comparisons of a species with itself and therefore represent structurally undefined self-comparisons rather than missing observations. Numerical uncertainty in trophic-position, SEAb, and niche-overlap estimates arises mainly from biological variability among individuals and from posterior uncertainty in the Bayesian models. This uncertainty is represented by posterior distributions and corresponding credible intervals rather than by a single deterministic error value. Stable isotope measurements were calibrated against international reference materials to reduce analytical bias. No additional numerical analytical error range is assigned where such instrument-specific precision was not independently quantified in the present dataset.The dataset is intended to provide a transparent and reproducible record of the observations and derived results used to evaluate spatial and temporal differences in trophic position, isotopic niche width, and interspecific resource-use similarity of the four fish species in Hongze Lake and Gaoyou Lake. Together with the accompanying R code, these data allow users to trace the major conclusions of the associated publication from individual stable isotope measurements to the final trophic-position, niche-width, and directional niche-overlap estimates. water level; trophic niche; trophic position; niche overlap 罗思 RESTRICTED dataset Science Data Bank