DOI: 10.5061/dryad.dv41ns299
title: Ecosystem shifts and Cladocera responses in a freshwater lake in semi-arid regions: The successional synergistic effects of natural and human factors in the past 170 years

description: The data of cladocera subfossils in the sediment core of Hulun Lake, the
 largest freshwater lake in northern China's semi-arid region
 (48.55°~49.33°N, 116.97°~117.81°E). The results indicate that
 both internal factors (such as lake sedimentary environment, fish catches,
 lake water level, organic matter, and nutrients) within the lake and
 external factors (including population, urbanization rate, and livestock
 husbandry) in the surrounding basin have been key drivers influencing the
 structure of Cladocera in Hulun Lake over the past 170 years. The
 originally predominant littoral Cladocera species (Chydorus sphaericus.
 sl.) were replaced by planktonic (Bosminidae) since 1980s accompanied by a
 decline in diversity, which corresponds with the process of eutrophication
 and pollution in the lake.
description: # Ecosystem shifts and Cladocera responses in a freshwater lake in
 semi-arid regions: The successional synergistic effects of natural and
 human factors in the past 170 years Dataset DOI:
 [10.5061/dryad.dv41ns299](10.5061/dryad.dv41ns299) ## Description of the
 data and file structure The data of Cladocera subfossils in the sediment
 core of Hulun Lake, the largest freshwater lake in northern China’s
 semi-arid region (48.55°~49.33°N, 116.97°~117.81°E). This is the raw data
 file of Cladocera community succession in Hulun Lake over the past 170
 years.  The column header 'Age (yr/AD)' represents the
 time series. The column headers from B to R (in %) refer to the species
 name of zooplankton Cladocera. The column header in S, 'Intotal
 individual (ind./g)', represents the absolute abundance of Cladocera.
 **Experimental procedures:** Approximately 1.5 g of dry sediment from each
 subsample of the HLH-9-1 core and surface sediment samples were used for
 the analysis of Cladocera subfossils. Cladocera remains were counted and
 identified based on their shells, headshields, postabdomens, and claws,
 following the identification methods outlined in Jiang and Du (1979),
 Szeroczyńska and Sarmaja-Korjonen (2007), and Xiang et al. (2015)). A
 minimum of 100 individuals were counted from each sample (Szeroczyńska and
 Sarmaja-Korjonen, 2007). **References** Jiang, X., Du, N., 1979. Fauna of
 China-Arthropod Phylum-Crustacean-Freshwater Cladocera. Beijing: Science
 Press, pp: 41-42. (In Chinese) Szeroczyńska, K., Sarmaja-Korjonen, K.,
 2007. Atlas of subfossil Cladocera from central and northern Europe.
 Swiecie: Friends of the Lower Vistula Society. Xiang, X.F., Ji, G.H.,
 Chen, S.Z., Yu, G.L., Xu, L., Han, B.P., Dumont, H.J., 2015. Annotated
 Checklist of Chinese Cladocera (Crustacea: Branchiopoda). Part I.
 Haplopoda, Ctenopoda, Onychopoda and Anomopoda (families Daphniidae,
 Moinidae, Bosminidae, Ilyocryptidae). Zootaxa 3904(1): 1-27. **Results:**
 A total of 14 Cladocera taxa from the families Bosminidae, Chydoridae, and
 Daphniidae, were identified in the HLH-9-1 core. The most abundant and
 widespread species in the sediments included the littoral species
 *Chydorus sphaericus*. sl*.* (mean relative abundance, 41%) and* Alona*
 spp. (mean relative abundance, 26%), as well as the planktonic species
 Bosminidae (including *Bosmina spp*., *Bosmina (E.) longispina* and *B.
 longirostris* with mean relative abundance of 24%) (Fig. 2). The
 meso-oligotrophic species of *Bosmina (E.) longispina* made up the largest
 proportion (6%) of the identified Bosminidae. Additionally, the* *littoral
 species of* Alona guttata* had a mean relative abundance of 6%. ##
 Code/software This dataset can be used with various software tools, such
 as Tilia program, to perform cluster analysis and visually illustrate the
 patterns of Cladocera community structure changes in Hulun Lake over the
 past 170 years.