Identifying suitable habitats and quantifying the spatial overlap among sympatrically distributed ungulates is essential for safeguarding their long-term survival. We deployed infrared cameras to capture the distribution sites of sika deer (Cervus nippon), Reeve’s muntjac (Muntiacus reevesi), and wild boar (Sus scrofa) in the Taohongling Sika Deer National Nature Reserve (TNNR) and measured nine environmental factors. Based on this, we applied MaxEnt modeling to assess the species’ habitat suitability and applied the Pianka index to evaluate niche overlap. The results showed that the sika deer occupied the smallest area of high-suitability habitat (53.85 km², 11.13% of the study area), primarily concentrated in the core zone of the TNNR. Specifically, 37.86% of the sika deer’s high-suitability habitat overlapped with wild boar and 29.06% overlapped with Reeve’s muntjac. Pianka index analysis revealed substantial spatial niche overlap between sika deer and Reeve’s muntjac (0.487) but limited overlap between sika deer and wild boar (0.160). Our findings indicate substantial overlap between sika deer and sympatric species. To effectively protect the sika deer in the TNNR, we recommend increasing the number of monitoring sites, implementing habitat improvement measures (e.g., vegetation restoration and water supplementation stations), and establishing isolation corridors to enhance habitat connectivity.

Species co-occurrence is closely linked to complex environmental changes and biological interactions in ecosystems. Freshwater ecosystems are among the most endangered ecosystems in the world, highly sensitive to environmental change, and rich in biodiversity. Clarifying the mechanisms of co-occurrence of zooplankton and phytoplankton, which are the basis of freshwater ecosystems, can provide important insights into ecosystem stability. We employed the Hierarchical Modeling of Species Communities (HMSC) within Joint Species Distribution Models (JSDMs) to fit the abundance data of zooplankton and phytoplankton dominant species sampled in April (spring) and July (summer) 2023 in Shengjin Lake to understand their co-occurrence pattern in typical Yangtze-connected lakes. Due to biotic interactions, rotifers primarily exhibit a positive co-occurrence pattern with one diatom and one cyanobacterium, while copepods mainly show a negative co-occurrence pattern with one diatom and one cyanobacterium. Only one rotifer and one chlorophyta mainly display a positive co-occurrence pattern, mainly driven by shared environmental preferences in that they are more likely to co-occur in areas with lower transparency, lower total phosphorus (TP) levels, and relatively higher pH levels. These findings show that the co-occurrence mechanisms of zooplankton and phytoplankton differ under the influence of biotic interactions and environmental factors, neither of which can be overlooked. These findings may provide important implications for the management of zooplankton and phytoplankton, the fundamental components of wetland ecosystems.

Considering the negative effects of wetland degradation, various measures have been implemented to restore wetland habitats for aquatic organisms, and their effectiveness levels must be assessed. To reduce the effects of aquaculture on aquatic communities, pen culture facilities, which are widely distributed in Yangtze-connected lakes, were removed in 2018. We surveyed and compared waterbird communities in Caizi Lake during the four months before (2017–2018) and after net pen removal (2021–2022) to evaluate their effect on the diversity and species composition of wintering waterbirds. After net pen removal, the richness and number of individual waterbird species increased, whereas the Shannon–Wiener diversity index did not change because the increase in the bird number throughout the year was mostly associated with a few species. The response of individual numbers of different guilds to the removal of net pens differed. The number of deep-water fish eaters, seed eaters, and tuber feeders increased, whereas that of invertebrate eaters decreased. The species composition also changed, particularly in the northeastern and southwestern parts of the lake. Differences in waterbird communities between the winters of 2017–2018 and 2021–2022 indicated that net pen removal had a positive impact on waterbird communities.

The degradation and loss of natural wetlands has caused severe crises for wetland taxa. Meanwhile, constructed wetlands are expanding significantly and facing dramatic environmental changes. Exploring the responses of wetland organisms, particularly zooplankton, may have important implications for the management of wetlands. Environmental and zooplankton samples were collected from 34 subsidence wetlands created by underground coal mining across the North China Plain in August 2021. We used generalized linear models and redundancy analysis to test zooplankton responses to environmental variables, with the relative importance quantified by variation partitioning. We identified 91 species, divided into 7 functional groups, with the highest density of rotifer filter feeders (RF, 2243.4 ± 499.4 ind./L). Zooplankton species richness was negatively correlated with electrical conductivity (EC), chlorophyll-a, total phosphorus, and pH. The Shannon–Weiner and Pielou evenness indices were positively correlated with transparency and negatively correlated with the photovoltaic panel area (AS). Rotifer predators (RCs) and RF densities were positively correlated with cropland area and dissolved oxygen, but negatively correlated with AS. Small crustacean filter feeders positively correlated with AS, whereas medium crustacean feeders (MCFs) positively correlated with EC. AS was the most critical variable affecting the zooplankton community. Our study showed that the spatial pattern of zooplankton communities was shaped by environmental heterogeneity across the subsidence wetlands, providing implications for the management and conservation of these constructed wetlands.