Habitat Evaluation Research Articles

Review of ecological valuation and equivalency analysis methods for assessing temperate nearshore submerged aquatic vegetation.

Nearshore seagrass, kelp, and other macroalgae beds (submerged aquatic vegetation [SAV]) are productive and important ecosystems. Mitigating anthropogenic impacts on these habitats requires tools to quantify their ecological value and the debits and credits of impact and mitigation. To summarize and clarify the state of SAV habitat quantification and available tools, we searched peer-reviewed literature and other agency documents for methods that either assigned ecological value to or calculated equivalencies between impact and mitigation in SAV. Out of 47 tools, there were 11 equivalency methods, 7 of which included a valuation component. The remaining valuation methods were most commonly designed for seagrasses and rocky intertidal macroalgae rather than canopy-forming kelps. Tools were often designed to address specific resource policies and associated habitat evaluation. Frequent categories of tools and methods included those associated with habitat equivalency analyses and those that scored habitats relative to reference or ideal conditions, including models designed for habitat suitability indices and the European Union's Water and Marine Framework Directives. Over 29 tool input metrics spanned 3 spatial scales of SAV: individual shoots or stipes, bed or site, and landscape or region. The most common metric used for both seagrasses and macroalgae was cover. Seagrass tools also often employed density measures, and some categories used measures of tissue content (e.g., carbon, nitrogen). Macroalgal tools for rocky intertidal habitats frequently included species richness or incorporated indicator species to assess habitat. We provide a flowchart for decision-makers to identify representative tools that may apply to their specific management needs.

Evaluation of fish habitat suitability based on stream hydrodynamics and water quality using SWAT and HEC-RAS linked simulation

The objective of this study was to evaluate fish habitat suitability by simulating hydrodynamic and water quality factors using SWAT and HEC-RAS linked simulation considering time-series analysis. A 2.9 km reach of the Bokha stream was selected for the habitat evaluation of Zacco platypus, with hydrodynamic and water quality simulations performed using the SWAT and HEC-RAS linked approach. Based on simulated 10-year data, the aquatic habitat was assessed using the weighted usable area (WUA), and minimum ecological streamflow was proposed from continuous above threshold (CAT) analysis. High water temperature was identified as the most influential habitat indicator, with its impact being particularly pronounced in shallow streamflow areas during hot summer seasons. The time-series analysis identified a 28% threshold of WUA/WUAmax, equivalent to a streamflow of 0.48 m3/s, as the minimum ecological streamflow necessary to mitigate the impact of rising water temperatures. The proposed habitat modeling method, linking watershed-stream models, could serve as a useful tool for ecological stream management.

Distribution and Habitat Selection of Indian Flying Fox, Pteropus medius (Temminck, 1825) in Uttar Pradesh, India

The present study examines the distribution and habitat selection of Indian flying fox, Pteropus medius in Uttar Pradesh, India. A through field work conducted across six districts revealed 22 roosting locations with a total population of approximately 12,023 bats. These sites were located at rural (12), semi-urban (2), urban (1), agricultural (5), and industrial (2) areas, and a majority of roost sites observed close to human habitations. Pteropus medius preferred to roost on 20 species of trees which indicate wide-ranging habitat preferences. Although there were considerable differences in tree attributes across different species, such as tree height (ranging from 9.54 to 26.03 meters), canopy width (varying from 8.59 to 25.09 meters), crown height (ranging from 1.19 to 18.90 meters), circumference (ranging from 0.54 to 3.65 meters), and DBH (ranging from 0.17 to 3.73 meters), and there was no notable variation in bat occupancy per roost tree. The results of the regression analysis emphasized the significance of canopy width as a predictor of colony size, indicating its importance in identifying suitable roosting habitats for P. medius. ANOVA analysis indicated differences in tree characteristics across species, highlighting the necessity for through habitat evaluations. Subsequent post-hoc examination clarified distinct clusters of tree species with significant variations in roosting site features. These results underscore the intricate relationship between tree attributes and bat populations, emphasizing the significance of well-informed conservation approaches for the sustainable preservation of P. medius and the overall ecosystem well-being.

Wildlife habitat suitability analysis and mapping the former dhidhessa wildlife sanctuary using GIS-based analytical hierarchal process and weighted linear combination methods

Management of wildlife populations and the creation of conservation programs depend on the evaluation of wildlife habitats. Habitat suitability mapping is a technique typically used to map appropriate environmental factors and assess species existence in different areas. This study aims to map wildlife habitat suitability sites in Former Dhidhessa wildlife sanctuary, Ethiopia, using GIS-based Analytical Hierarchal Process and Weighted Linear Combination Methods. This study used both primary and secondary data sources. Datasets used to collect data include Digital Elevation Model (DEM), Landsat 9 (OLI/TIRS) and population data. Beside, large mammalian species occurrence data obtained from field survey was used. To map wildlife habitat suitability sites in Former Dhidhessa wildlife sanctuary, environmental factors such as proximity of road network, distance to surface water, land use land cover types, slope, population density and topography were used with the integration of species occurrence data recorded from the study area. These environmental factors scaled to common ranges, and assigned appropriate weights. The quantile classification method was utilized to classify suitability index into five zones (unsuitable, less suitable, moderately suitable, suitable, and highly suitable) to produce the map. Accordingly, the model revealed that 18.9 % of the study area is highly suitable, 19.5 % is suitable, 19.9 % is moderately suitable, 19.5 % is less suitable, and 22.2 % is unsuitable for wildlife. About 58.3 % of the study area is currently identified as suitable for wildlife whereas 41.7 % is unsuitable. This showed that the former Dhidhessa wildlife sanctuary is still having large suitable habitats that can support wide ranges of wildlife. Hence, based on the developed preliminary habitat suitability indices and maps, the federal and local governments shall reevaluate the status of former Dhidhessa wildlife sanctuary and develop future conservation and management plans to enhance the conservation of wildlife and their habitats in the area.

An annotated avian checklist of Bornadi Wildlife Sanctuary, Assam, India

The Bornadi Wildlife Sanctuary (BWS) boasts a variety of habitats, including forest, riparian, degraded forest, and transitional zones located near human settlements and cropland. From 2019 to 2022, a thorough avian survey was conducted using the point count method, covering all habitats and seasons. The study documented 227 avian species from 65 families and 18 orders. Of the bird species observed, 72.3% were resident, and 27.7% were migratory. Over the study period, one Endangered species, three Vulnerable, and six Near Threatened species were recorded based on their IUCN Red List status. The avian diversity pattern in BWS is influenced by a variety of factors, including forest contiguity and heterogeneous habitat. Proper evaluation and management of habitats are essential for the recovery and preservation of fragile environments susceptible to decline in the region.

Suitable habitat evaluation and ecological security pattern optimization for the ecological restoration of Giant Panda habitat based on nonstationary factors and MCR model

Enhancing the regional connectivity, coordination, and integrity of Giant Panda National Park can protect giant pandas. The construction and optimization of the ecological security pattern in giant panda habitat can effectively promote the information exchange among giant panda populations of Giant Panda National Park in Ya'an area. Based on climate change, geographic location, human activities, and other factors, the Maxent model was used to evaluate the non-stability of giant panda habitat suitability, and the minimum cumulative resistance (MCR) model was used to construct the ecological security pattern. Based on the gravity model and relevant image verification analysis, we proposed an optimal solution to the ecological problem of giant panda corridor groups. From our research, good habitat suitability of giant pandas was detected, with a high degree of local fragmentation. The areas of the most suitable habitat, the more suitable habitat, and the generally suitability were 1970.12 km2, 2346.51 km2, and 1902.37 km2, respectively. Suitable habitat was located between 2100 m and 3400 m in elevation, with a less than 30° slope. The average temperature of the coldest season in the suitable area was around - 2 ∼ 2 °C, the precipitation of the wettest month was between 140 ∼ 160 mm, and the mean diurnal range was between 9 ∼ 14 °C. Valuation results for nonstationary factors beyond these ranges will not fall within the Habitat Suitability Zone. In total, 13 ecological sources, 13 ecological corridors, 6 ecological barrier points, and 4 ecological pinch points were identified and divided into 4 ecological corridor groups to locate and repair ecological problems, achieving the purpose of building and optimizing ecological security patterns. The integrated technical frame work proposed in this work, which combined the suitability evaluation, ecological safety pattern construction and ecological restoration, considered the nonstationary variations in factors and the actual species ranges. It also emphasized the importance of the relationship between the species’ suitability and the ecological security pattern. The results of this work have important implications for examining the habitat modifications, gene exchange between giant panda populations, and habitat conservation of giant pandas.

Multi-index evaluation of fish habitat in a cascaded hydropower reservoir of the Yangtze River, China

Cascaded hydropower development in rivers has a greater negative impact on native fish than a single hydropower station. The effectiveness of commonly used measures to restore fish resources, such as ecological discharges, depends largely on reliable assessments of habitat quality. In this study, we developed a synthesized habitat quality index (SHQI) by combining the habitat suitability index (HSI) and habitat fragmentation indices to evaluate the fish habitat in the Longkaikou (LKK) reservoir between the Jinanqiao (JAQ) and LKK dams in the upper Yangtze River. We coupled a 2-dimensional physical habitat model and a fuzzy-logic habitat suitability model for spawning and juvenile Coreius guichenoti, an Endangered fish endemic to the Jinsha River basin. The impact of the JAQ reservoir flow and the impoundment level of the LKK reservoir were considered to analyze variation in habitat quality. The results revealed that habitat suitability and fragment conditions were, to some extent, spatially inconsistent. The SHQI suggested lentic areas could benefit juvenile fish more than lotic zones with higher quality but less connectivity. A higher impounded level of the LKK reservoir may be more favorable for juvenile fish in the lentic area. Only the lotic area was suitable for fish spawning, and a lower discharge from the JAQ reservoir and lower impounded level of the LKK reservoir could be more beneficial, with optimal values of 560 m3 s-1 and 1294 m, respectively. This study proposes a comprehensive assessment method for habitat quality that could provide scientific support for the conservation of fish resources and populations in cascaded hydropower developments.

Can rewilding with giant tortoises increase woody habitat and limit fire across Madagascar's grasslands?

Societal Impact StatementTo better understand the impact of human settlement on vegetation distribution and disturbance regimes in Madagascar, the 2021 Malagasy Grassy Biomes Workshop called for an examination of the role of extinct megafauna in determining the historic distribution of habitat mosaics across regions that are today dominated by vast treeless grasslands. A systematic literature review facilitated the reconstruction and evaluation of giant tortoise habitat, feeding habitats, diets and Aldabrachelys tortoise impacts on disturbance regimes. In conclusion, reintroduction of mixed‐feeding Aldabrachelys (the diets of which were often dominated by C3 woody material, but never by C4 grasses, across its range), will likely impact plant species composition, select a tree‐rich habitat mosaic, reduce fire frequency, re‐establish lost ecological functions and improve landscape productivity at a range of scales, including rangeland palatability, benefitting both biodiversity and human wellbeing.SummaryGrasslands with little tree cover today comprise 80% of Madagascar's habitat. Determining their extent at human settlement can guide ecological restoration and enhance human well‐being, so the 2021 Malagasy Grassy Biomes Workshop identified the role of extinct megafauna in determining habitat as a critical knowledge gap. Using a systematic literature review, combined with extracted datasets, we address this, examining anticipated habitat selection by giant tortoises following reintroduction to Madagascar (where the Aldabran giant tortoise, Aldabrachelys gigantea, provides ecological functions lost when A. abrupta and A. grandidieri went extinct). When comparing current and historical tortoise selection of habitat across the Mascarenes and Aldabra with contemporary Malagasy habitat, areas in Madagascar where giant tortoises historically ranged, today have a significantly different habitat composition to the forested habitat that supported giant tortoises on other islands. Dietary 13C isotope ratios show that Malagasy Aldabrachelys and Mascarene tortoises were mixed feeders, with diets often dominated by C3 woody intake, but never by C4 grasses. Across systems, giant tortoises required and selected, tree‐rich habitat mosaics, different to current pastoralist fire‐selected Malagasy grasslands characterized by sparse tree cover. Furthermore, Aldabran Aldabrachelys tortoise turf, restricted to small areas (large tracts of unshaded vegetation present physiological challenges to Aldabrachelys' survival), is compositionally different to Malagasy and African obligate C4 grazing lawns. Ecological, palaeoecological, geomorphological and molecular evidence support a lost Malagasy habitat mosaic where hippo and tortoise diets were C3‐dominated, because they inhabited closed‐canopy systems, with abutting open‐canopy areas harbouring endemic‐rich, C4 grassy understories and limited grasslands. The review suggests that rewilding with A. gigantea will help restore ecological functions, productivity and landscape‐scale degradation lost through cattle‐based pastoralism, re‐establish tree‐rich habitat mosaics, and mitigate against frequent bushfires, benefiting biodiversity and humans at multiple scales.

Morphological and Habitat Quality of Salmonid Streams and their Relationship with Fish-Based Indices in Aotearoa New Zealand and Ontario (Canada).

Habitat degradation is one of the major reasons for freshwater species decline. Hydrogeomorphological processes (such as sediment transport, bank erosion, and flooding) operate at the catchment scale and determine habitat features in river reaches. However, habitat quality indices and restoration for freshwater fish species are often implemented at small spatial scales of a few hundred metres. The Morphological Quality Index (MQI) considers fluvial processes at larger scales as well as channel forms, human impacts, and historical changes, but few studies have assessed its relevance for ecosystem health. We investigated relationships between the MQI, habitat quality (using the Qualitative Habitat Evaluation Index, QHEI), land cover, and fish metrics (number of fish species, index of biotic integrity (IBI), and trout biomass) in 26 salmonid streams in Aotearoa New Zealand and Southern Ontario, Canada. We found a significant correlation between the MQI and QHEI, and both metrics were correlated with urban and native forest proportion in the catchment. However, we found no relation between the MQI and the proportion of agricultural land in the catchment, while the QHEI was correlated with agricultural land in the riparian zone, highlighting the importance of vegetated riparian buffers in providing fish habitat. Establishing a strong correlation with fish metrics remains challenging. Nevertheless, a modified MQI targeting ecological health could be used as an effective management tool for aquatic conservation.

Population assessment of the Endangered Forty-spotted Pardalote Pardalotus quadragintus on Maria Island, Tasmania

The Forty-spotted Pardalote Pardalotus quadragintus is one of the smallest birds in Australia and is endemic to Tasmania, where it occurs only in forest or woodland containing White Gum Eucalyptus viminalis. It is listed as Endangered under the Tasmanian Threatened Species Protection Act 1995 and Commonwealth Environment Protection and Biodiversity Conservation Act 1999. A habitat-stratified survey of Forty-spotted Pardalotes on Maria Island, off the eastern coast of Tasmania, was undertaken in August 2023 to provide a robust estimate of the population. Initial stratification using available vegetation mapping overestimated the availability of suitable habitat based on survey-site habitat evaluations. Forty-spotted Pardalotes were detected at 14 of 74 survey sites, with all detections being at sites where White Gum was the main tree species present. Their mean density was 1.66 birds per hectare, with an estimated total population of 847 birds (CV 0.38, confidence intervals 404–1776 birds). This estimate is consistent with previous uncorrected count-based estimates, although comparisons with historical counts are highly subjective given the substantial methodological differences. Only ~5% of Maria Island supports the preferred habitat for this species and further research on the requirements for, and abundance of, suitable microhabitat is recommended to further refine population estimates and guide conservation management actions.

Setting priorities and evaluation of habitats for the conservation of orthopterans: case study in the Aggtelek National Park (N Hungary)

The biodiversity conservation needs recent high-quality data and efficient methods for prioritizing species and sites for conservation. Here we prioritized Orthoptera habitats of the Aggtelek National Park, based on revised and actualized distribution data of 69 Orthoptera species living at 98 sites. The simple ranking and complementary areas methods were used with species richness (S), rarity weighted species richness (SR), and number of rare species (SQ). Additionally, the Grasshopper Conservation Indexes (GCI” and GCIn”) combining European and local rarity and dispersal capacity of the species were also tested. Contrary to simple ranking the complementary areas method represented the whole fauna and significant part of the species-site data records. All the used indices performed similar except the standardized GCIn” which is highly affected by the differences in study intensity of sites. High-priority areas of the Aggtelek National Park were designated in the plateau above Jósvafő and Aggtelek villages and in the small, isolated hill near Jósvafő (Szőlő-hegy) covered with remained mosaic of former vineyards, orchards and hayfields. The combined use of the efficient indices provides additional ranking that allows the best selection of hotspots to support efficient use of limited resources in nature conservation.

Sustainable Conservation Management System for The Critically Endangered Betta Persephone in Ayer Hitam Peat Swamp Forest Reserve Muar Johor

In recent years, there has been a lot of interest in protecting and conserving wildlife on a wide range of scales. Betta Persephone’s habitat life may be affected by urbanization in Ayer Hitam Peat Swamp Forest Reserve (AHPSFR). This species is endangered due to the widespread conversion of peat swamp forests to industrial forestry and monoculture plant. The evaluation of fish habitat always has been a research priority for individuals in the domains of environmental protection and sustainable development, to improve habitat conservation. Results of the study through sample water collection shows the result of pH water. Based on these environmental factors, the factors that under dry leaves and branches and blackwater are the main factors that affect Betta Persephone choose AHPSFR as its own natural habitat. The satellite data and to analyze the catchment area results and construct the maps. U.S Geological System (USGS) and Geographic Information System (GIS) used to generate the maps. Geographic Information System (GIS) is a computer system that analyses and displays information that is geographically referenced. This study is carried out to predict the hydrologic analyze of the study area. The location of Betta is at one of the small sub catchments at the study area. The sub catchment that are found of the habitat are at the nearly the low stream links and at the watershed area that are found using the software.

Assessing the Inclusion of Critical Habitat Evaluation in Nigeria's Environmental Impact Assessment (EIA) Reports: A Crucial Step towards Biodiversity Conservation and Sustainable Development

Assessing the Inclusion of Critical Habitat Evaluation in Nigeria's Environmental Impact Assessment (EIA) Reports: A Crucial Step towards Biodiversity Conservation and Sustainable Development

An Evaluation of Suitable Habitats for Amur Tigers (Panthera tigris altaica) in Northeastern China Based on the Random Forest Model.

Amur tigers are at the top of the food chain and play an important role in maintaining the health of forest ecosystems. Scientific and detailed assessment of the habitat quality of Amur tigers in China is the key to maintaining the forest ecosystem and also addressing the urgent need to protect and restore the wild population of Amur tigers in China. This study used the random forest method to predict the potential habitat of Amur tigers in Heilongjiang and Jilin provinces using animal occurrence sites and a variety of environmental variables. Random forests are a combination of tree predictors such that each tree depends on the values of a random vector sampled independently and with the same distribution for all trees in the forest. The generalization error for forests converges to a limit as the number of trees in the forest becomes large. The generalization error of a forest of tree classifiers depends on the strength of the individual trees in the forest and the correlation between them. The results showed that the AUC value of the test set was 0.955. The true skill statistic (TSS) value is 0.5924, indicating that the model had good prediction accuracy. Using the optimal threshold determined by the Youden index as the cutoff value, we found that the suitable habitat for Amur tigers in the field was approximately 107,600 km2, accounting for 16.3% of the total study areas. It was mainly distributed in the Sino-Russian border areas in the south of the Laoyeling Mountains at the junction of Jilin and Heilongjiang provinces, the Sino-Russian border areas of Hulin-Raohe in the eastern part of the Wanda Mountains, and the Lesser Khingan Mountain forest region. The habitat suitability of the Greater Khingan Mountain and the plain areas connecting Harbin and Changchun was relatively low. Prey potential richness was the most critical factor driving the distribution of Amur tigers. Compared with their prey, the potential habitats for Amur tigers in Heilongjiang and Jilin provinces were small in total areas, sporadically distributed, and had low continuity and a lack of connectivity between patches. This indicates that some factors may restrict the diffusion of the Amur tiger, whereas the diffusion of ungulates is less restricted. The Amur tigers in this area face a serious threat of habitat fragmentation, suggesting that habitat protection, restoration, and ecological corridor construction should be strengthened to increase population dispersal and exchange. We provide a reference for future population conservation, habitat restoration, construction of ecological migration corridors, and population exchange of Amur tigers.

CA|RDS Lite: A rapid assessment of site management against the Conservation Assured | River Dolphin Standards

This paper introduces the inaugural rapid evaluation of river dolphin habitats, coinciding with managed sites in Asia and South America. Covering all six river dolphin species (including the sole freshwater porpoise worldwide), each is classified as Endangered or Critically Endangered on the IUCN Red List. The Conservation Assured | River Dolphin Standards (CA|RDS) offer tailored guidelines for the proficient oversight of protected areas for river dolphins. The abbreviated CA|RDS version, termed CA|RDS Lite, involves a questionnaire-based survey conducted by managers and stakeholders at 40 sites across 10 of the 14 countries within the river dolphin range. Both continents face river dolphin endangerment from fishing and climate change. In Asia, risks are more diverse, with smaller populations compared to South America. Insufficient funding and management capacity emerge as significant hurdles. Inadequate collaboration with areas outside the protected area boundary impedes effective river dolphin population management. Encouragingly, the survey highlights active involvement of local communities and stakeholders in site management. CA|RDS Lite offers a quick overview of site management efficacy, pinpointing crucial management requirements and urgent river dolphin sites necessitating intervention. It also sets the stage for the complete application of CA|RDS standards and their use as an accreditation and management instrument.

Research on a Multi-Species Combined Habitat Suitability Assessment Method for Various Fish Species

To reveal the evolution of habitat distribution for multiple fish species in the lower reaches of the Gongzui Hydropower Station, this study conducted a catch survey to determine the target species of the reach. Based on their suitability curves, a combined suitability assessment model for multiple fish species was constructed. The reliability of the model was verified by combining acoustic observations of flow fields and fish distribution in specific flow conditions. A two-dimensional hydrodynamic model was coupled to quantitatively analyze the distribution characteristics of fish habitat patches under different flow conditions. The results indicate that the correlation coefficient between the multi-species comprehensive suitability index and the number of fish is 0.676, which indicates that the model can better evaluate the distribution of multiple fish habitats in the study river reach; the weighted usable area (WUA) decreased as the discharge increased; from low flow condition (<800 m3/s) to high flow condition (>2000 m3/s), the patch area of suitable habitat decreased from 11,424 m2 to 1268 m2, and the connectivity between patches also showed a downward trend; and the habitat shifted to the near-shore area of the downstream wider and shallower section, which was highly correlated with the migration process of low-depth and low-velocity areas. The model proposed in this study can establish a rapid response between the suitable habitat distribution of multiple fish species and discharge conditions, which can provide a research method for quantitative evaluation of multi-species habitats in river, and make a significant contribution to the sustainable development of riverine fisheries resources and river water ecology.

Health Assessment of the Stream Ecosystem in Beijing, China

With economic development, the health of river ecosystems is becoming severely threatened because of the increasing effects of human activities on river ecosystems. Here, 101 sites along regional river systems in Beijing rivers were investigated from autumn 2020 to summer 2021. A total of 34 metrics, including aquatic organisms, hydrology, water quality, and habitat, were calculated to be the candidate indicators. Principal component and correlation analyses were used to select the core metrics from the candidate indicators, and the weight of each core metric was estimated using the entropy method. The integrated index of stream ecological health was constructed to assess the health condition of the Beijing rivers. The results of the PCA and correlation analyses revealed that eleven metrics were selected as the core metrics to construct the integrated index of stream ecological health, including water temperature, flow velocity, BOD5, NH4+-N, Cu, the density of phytoplankton and zooplankton, the Shannon-Wiener diversity index of macroinvertebrates and fish, the BMWP index, and the qualitative habitat evaluation index. According to the health assessment results, 4.95% of the sampling sites were healthy, 23.76% were subhealthy, and 71.29% were in a fair or below healthy state. The river health status showed strong spatial heterogeneity, and the river health statuses in the northern and western regions were relatively good, whereas the river health status in the central and southeastern regions were relatively poor. The results of four aspects stream ecosystem assessment showed that the overall water quality of the rivers was "subhealthy" and the aquatic organisms and habitat were "general poor," but the hydrology was "poor." The evaluation results of five water systems demonstrated that the Chaobai River had the best health status, followed by that of the Yongding River, Daqing River, and Jiyun River, and the Beiyun River had the worst health status. Maintaining river ecological baseflow, ensuring river system connectivity, and improving and restoring the river habitat environment are the key aspects of river ecological restoration and protection in Beijing in the future.

Estimation of least ecological streamflow through long-term habitat evaluation using stream hydrodynamics and water quality factors

ABSTRACT The objectives of this study were to evaluate aquatic habitat suitability considering stream hydraulics as well as water quality and to propose a stream ecological flow rate for Zacco platypus in the Banbyeon Stream of South Korea. Stream water temperature and dissolved oxygen (DO) in addition to streamflow velocity and depth were simulated using the Hydrologic Engineering Center-River Analysis System (HEC-RAS) from 2010 to 2020 and then used to estimate weighted usable area (WUA) as the proxy indicator of stream habitat suitability. The continuous above-threshold (CAT) analysis revealed several anomalous drops in WUA as the combined effect of water temperature rise and streamflow reduction. A WUA/WUAmax ratio of about 24% seems to be a threshold level below which water temperature rises more rapidly as streamflow decreases. This is equivalent to a streamflow rate of 3.6 m3/s and is proposed as the least ecological streamflow to sustain minimal aquatic habitat suitability.

Evaluation of Threatened, Endangered, and Rare Fish Species and Communities of the St. Lawrence River and Its Tributaries in the United States

Biodiversity is responsible for important ecological processes like productivity and ecosystem stability, and rare species are a major component of biodiversity. Rarity increases a species' vulnerability to disturbances and also makes them difficult to study. Globally, species of freshwater systems are some of the most threatened, and evaluation of rare freshwater species and their habitats is needed to help preserve natural flexibility and ecological function. We conducted an analysis of full fish communities of the upper St. Lawrence River and its major US tributaries, with the goals of determining species locations and abundances, associated environmental conditions, the distribution of distinct fish assemblages across the landscape (with emphasis on communities supporting rare species), and potential threats. From 2009 to 2015, the US Geological Survey (USGS) and Saint Regis Mohawk Tribe (SRMT) worked together using standardized methods to collect community samples within 4 different aquatic realms (shallow and deep lentic, and small and large lotic systems) and determine species-specific fish abundances, frequencies of occurrence, and associated habitat signatures and spatial distributions. Distinct fish assemblages and associated habitat conditions were objectively identified by multivariate and hypothesis-testing methods. We used a geographic information system (GIS) to spatially associate habitat, biotic, and landscape attributes within each stream reach throughout the study area, facilitating quantification of distribution patterns. Comparisons with historical data provided estimates of loss or gain of threatened and endangered species (T&E) colonies. We developed a disturbance index to highlight potential threats to aquatic species. More than 140,000 fishes of 87 species were collected from a total of 1140 sample sites, covering 278 stream reaches, including the endangered Notropis anogenus (Pugnose Shiner), and threatened Hiodon tergisus (Mooneye), Etheostoma pellucidum (Eastern Sand Darter), and Acipenser fulvescens (Lake Sturgeon). We identified 50 distinct fish assemblages differing in species composition, abundance, and/or diversity, but only 13 of those assemblages included a T&E species. The rareness, extent, and patchiness of fish assemblages created a mosaic of fish communities across the landscape, from headwaters to the mainstem of the St. Lawrence River. Comparisons with historic surveys (1978–2008) showed a stable number of T&E species colonies or an increase for some species. The geographic distribution of multimetric disturbance index values showed where combinations of disturbances to fish habitats might affect rare fish species and aquatic communities in the region. The species–habitat associations and fish assemblage distributions can be used for evaluation of species, communities, or habitats that may need protection or restoration.

Waterline digital elevation model development to quantify inundation duration and coastal protection of tidal wetlands

Coastal tidal wetlands are sufficiently acknowledged for the supplied vital ecosystem functions, including flood protection and biological conservation. Measuring and estimating reliable topographic data is essential for quantifying mangrove habitat quality. This study proposes a novel methodology for quickly constructing a digital elevation model (DEM) with an instantaneous waterline combined with tidal level records. Unmanned aerial vehicles (UAVs) enabled on-site waterline interpretation analysis. The results show that image enhancement improves the accuracy of waterline recognition and object-based image analysis has the highest accuracy. The waterline DEM (WDEM) performs a more accurate elevation production than UAV DEM, indicating that its application to habitat evaluation and prediction could be more reliable. Hydrodynamic simulations incorporated with the mangrove habitat model were utilized to calculate inundation duration, flow resistance, and vegetation dissipation potential according to the verified WDEM. The larger the mangrove coverage ratio, the stronger the flow resistance, which means that the protective consequence of the mangrove on the natural embankment is evident. The WDEM and nature-based solutions presented facilitate an adequate understanding of coastal protection and promote the potential ecosystem-based disaster risk reduction of mangrove wetlands.