Suitable habitat mapping in the Yangtze River Estuary influenced by land reclamations

Sun

Xue

et al. 2017

Ecological Indicators

Self Cite

Here, we propose an approach to environmental flow assessment that pays attention to species dispersal among fragmented potential habitat patches affected by river inflow and tidal currents in estuaries. The approach consists of three steps. In step one, potential suitable habitats were mapped and the Habitat Aggregation Index (HAI) was determined to understand the fragmentation of potential suitable habitats by integrating the requirements for critical environmental factors that have temporal and spatial variability. In the second step, an individual-based model was developed to simulate the dispersal of target species among potential habitat patches. The model provided the species distributions for altered hydrological processes. In the third step, environmental flows were defined by comparing the occupancy of suitable habitat patches by individual organisms and habitat aggregation for varying freshwater inflows. This approach was tested using a case study in the Yangtze River Estuary. We stressed the ecological importance of flood pulse, rather than average discharge, and recommend a Gaussian-type flood pulse, as provides a win-win point for both the numbers of individuals that could occupy suitable habitat and the HAI. We also demonstrated the importance of the peak flow and flood pulse duration in terms of affecting species distribution. Based on the results presented here, the proposed approach offers a flexible assessment of environmental flow for aquatic ecosystems.

Section: Resultssupporting

confidence: 69%

Section: Mapping Potential Habitat Distributionsmentioning

confidence: 99%

Environmental flow assessment in estuaries taking into consideration species dispersal in fragmented potential habitats

Sun

Xue

et al. 2017

Ecological Indicators

Self Cite

“…The habitat suitability index (HSI) is widely used in species habitat evaluation and can be obtained from the model outputs [43][44][45][46]. For further analyses, HSI was classified into four levels of habitat suitability [47]: unsuitable (HSI < 0.3), marginally suitable (0.3 ≤ HSI < 0.5), moderately suitable (0.5 ≤ HSI < 0.7), and highly suitable (HSI ≥ 0.7).…”

Section: Data Analyses Of Key Bioclimatic Variables and Habitat Suitamentioning

confidence: 99%

Non-Pessimistic Predictions of the Distributions and Suitability of Metasequoia glyptostroboides under Climate Change Using a Random Forest Model

Wei

et al. 2020

Forests

Metasequoia glyptostroboides Hu & W. C. Cheng, which is a remarkable rare relict plant, has gradually been reduced to its current narrow range due to climate change. Understanding the comprehensive distribution of M. glyptostroboides under climate change on a large spatio-temporal scale is of great significance for determining its forest adaptation. In this study, based on 394 occurrence data and 10 bioclimatic variables, the global potential distribution of M. glyptostroboides under eight different climate scenarios (i.e., the past three, the current one, and the next four) from the Quaternary glacial to the future was simulated by a random forest model built with the biomod2 package. The key bioclimatic variables affecting the distribution of M. glyptostroboides are BIO2 (mean diurnal range), BIO1 (annual mean temperature), BIO9 (mean temperature of driest quarter), BIO6 (min temperature of coldest month), and BIO18 (precipitation of warmest quarter). The result indicates that the temperature affects the potential distribution of M. glyptostroboides more than the precipitation. A visualization of the results revealed that the current relatively suitable habitats of M. glyptostroboides are mainly distributed in East Asia and Western Europe, with a total area of approximately 6.857 × 10 6 km 2 . With the intensification of global warming in the future, the potential distribution and the suitability of M. glyptostroboides have a relatively non-pessimistic trend. Whether under the mild (RCP4.5) and higher (RCP8.5) emission scenarios, the total area of suitable habitats will be wider than it is now by the 2070s, and the habitat suitability will increase to varying degrees within a wide spatial range. After speculating on the potential distribution of M. glyptostroboides in the past, the glacial refugia of M. glyptostroboides were inferred, and projections regarding the future conditions of these places are expected to be optimistic. In order to better protect the species, the locations of its priority protected areas and key protected areas, mainly in Western Europe and East Asia, were further identified. Our results will provide theoretical reference for the long-term management of M. glyptostroboides, and can be used as background information for the restoration of other endangered species in the future.

“…E. sinensis is an ecologically and commercially important fishery species in the YRE, characterized by its wide distribution, environmental tolerance, rapid growth, high reproductive capacity, broad diet, and gregarious behavior (Li et al 2011). Furthermore, it also represents a typical deteriorating fishery resource in the YRE, with annual yields plummeting from 46.3 to 2.0 tons due to overfishing and habitat degradation (Xue et al 2016). The conservation of E. sinensis is one of the main concerns of environmental managers in the YRE.…”

Section: Introductionmentioning

confidence: 99%

Estimation of estuarine habitat degradation and its influence on the reproduction process of the crab Eriocheir sinensis in the Yangtze River Estuary

Zhang,

Du,

Geng

et al. 2023

Ecol Process

Background The provision of habitat for fishery species in estuaries is highly valued and represents one of the most challenging ecosystem service values to quantify. However, quantifying this value is challenging due to complex relationships between habitat change, ecological processes, and environmental variations. This study aims to estimate estuarine habitat degradation and its impact on the reproduction process of the crab Eriocheir sinensis by characterizing the changes in breeding habitat and investigating relationships between the species and its habitat in the Yangtze River Estuary. Methods A species distribution model recently developed was applied to estimate the extent and quality of breeding habitat changes from 2014–2021. The intrinsic (physiological) and external (structural) reproductive attributes of the breeding process were measured to assess the effects of habitat change. The relationships among habitat change, reproductive attributes and environmental factors were analyzed to understand the underlying driving forces of habitat degradation for breeding process by multivariate statistical analysis. Results About 34.24% of essential habitat was lost, mainly in highly suitable areas due to reclamation and waterway construction. Habitat degradation significantly affects female distribution and their reproductive processes, particularly gonad development during the pre-reproductive period and fecundity during the reproductive period, without altering population structure. These results indicated that the main ecological function served by the highly suitable breeding ground was the provision for development of gonad and improvement of fecundity. Increases of salinity and turbidity, caused by hydrodynamic changes from large-scale waterway construction, were identified as the environmental determinants contributing to cumulative habitat degradation. These influences ultimately led to a decrease in the fecundity of E. sinensis. Conclusions Our research sheds light on the quantification of habitat degradation in the Yangtze River Estuary and its implications for the reproduction process of E. sinensis, which can serve as a foundation for assessing and quantifying the ecosystem service values provided by these breeding grounds. This information is valuable for policymakers and resource managers in making informed decisions regarding habitat conservation and the sustainable utilization of fishery resources.