Ecological Hotspots Research Articles

Enhancing nitrate removal from small wetlands via regulating bacterial-algal symbiosis with macrophyte coverage

With increasing land resource constraints, wetlands, as ecological hotspots, are expected to enhance biogeochemical processes to mitigate nitrogen (N) pollution, particularly nitrate-nitrogen (NO3−-N). However, the interactions among bacteria, algae, and macrophytes in wetlands, which are crucial for N removal, remain largely unknown. This study explored how macrophyte coverage influences bacterial-algal interactions, shifting from mutualism to inhibition, thereby affecting N removal. Moderate coverage enhanced NO3−-N and total nitrogen (TN) removal (P < 0.05), which was correlated with increased microbial abundance (P < 0.05). This may have resulted from moderate algal photosynthesis, reduced physiological stress, and the expansion of ecological niches for microbes. Insufficient coverage promoted algal growth (chlorophyll-a > 31.8 μg·L−1), leading to increased competition for substrates and elevated pH, which further inhibited bacterial activity. Excessive coverage also inhibited bacterial activity by reducing illumination and oxidation-reduction potential. Consequently, insufficient and excessive coverage decreased N removal efficiencies by 2.7–15.7 % (NO3−-N) and 3.7–11.1 % (TN) while increasing methane emission potential by 1.4–6.9 times compared with moderate coverage. These findings offer insights into solving NO3−-N contamination using near-natural methods and balancing the ecological and practical considerations for small wetlands.

Metabolic adaptations underpin high productivity rates in relict subsurface water

Groundwater aquifers are ecological hotspots with diverse microbes essential for biogeochemical cycles. Their ecophysiology has seldom been studied on a basin scale. In particular, our knowledge of chemosynthesis in the deep aquifers where temperatures reach 60 °C, is limited. Here, we investigated the diversity, activity, and metabolic potential of microbial communities from nine wells reaching ancient groundwater beneath Israel’s Negev Desert, spanning two significant, deep (up to 1.5 km) aquifers, the Judea Group carbonate and Kurnub Group Nubian sandstone that contain fresh to brackish, hypoxic to anoxic water. We estimated chemosynthetic productivity rates ranging from 0.55 ± 0.06 to 0.82 ± 0.07 µg C L−1 d−1 (mean ± SD), suggesting that aquifer productivity may be underestimated. We showed that 60% of MAGs harbored genes for autotrophic pathways, mainly the Calvin–Benson–Bassham cycle and the Wood–Ljungdahl pathway, indicating a substantial chemosynthetic capacity within these microbial communities. We emphasize the potential metabolic versatility in the deep subsurface, enabling efficient carbon and energy use. This study set a precedent for global aquifer exploration, like the Nubian Sandstone Aquifer System in the Arabian and Western Deserts, and reconsiders their role as carbon sinks.

Zooplankton in the zones of transformation of river runoff in the north-western Black Sea region and the Mediterranean Sea in 2017–2020

Estuary zones play a key role in the regulation of the impact of continental processes on marine ecosystems. The zone “river–sea” is a unique area with specific conditions, geochemical and biological processes. They belong to the so called “ecological hot spots” and that is why their research is especially needed to understand possible changes in the ecosystems. In the present study we described the spatial distribution of zooplankton in the zones of transformation of river runoff in the Ukrainian part of the north-western Black Sea region and the Turkish coast of the Mediterranean Sea in 2017–2020. In the Black Sea, samples were collected from the coast of the Odesa Marine Region, Danube Region and coastal waters between Dnipro-Bug estuary and Yuzhne town. On the Turkish Mediterranean Sea coasts, samples were collected between Antalya city and Patara village (Mugla province). A total of 64 samples of the zooplankton were studied. We did not establish a direct dependence between zooplankton biomass and annual volume of river runoff (correlation between these metrics is from –0.25 to –0.80). 20 taxa of zooplankton in the Odesa Marine Region, 21 taxa in the Danube Region, 11 taxa in the Dnieper Region, 23 taxa in the Turkish coastal zone of the Mediterranean Sea were registered. Species of forage zooplankton were dominant over non-forage ones in all seasons and all investigated aquatoria. The percentage of Noctiluca scintillans (Macartney) Kofoid &amp; Swezy, 1921 and jellyfish did not exceed 5% of the total biomass of zooplankton. In summer in the Black Sea, the majority of zooplankton by number and biomass was formed by organisms of meroplankton, species of Cyclopoida and Harpacticoida, in autumn species of the genus Acartia, Oithona davisae Ferrari F. D. &amp; Orsi, 1984, larvae of Cirripedia and Penilia avirostris Dana, 1849. The number and biomass of adults and Copepodid Stages of Acartia species increased from spring to autumn in all years. In populations of Acartia species Copepodid stages predominated over adults by number and biomass in all seasons. In the Mediterranian Sea, the majority of zooplankton by number and biomass was formed by larvae of benthic invertebrates and Copepoda. The abundance and biomass of zooplankton at a distance of 300 m from the river mouth were greater than directly at the mouth. The hydro-front was expressed near all investigated rivers, the maximum values of zooplankton number and biomass were observed here and they decreased in direction both towards the mouth of the river and towards the open sea.

Short-term geomorphic adjustments of bars in the Elbe, a large regulated river in Czechia

Gravel and sandy bars constitute critical components of river channel morphology, yet their morphodynamics in large, heavily regulated rivers during periods without significant flows remain poorly understood. This study investigates changes in surface heterogeneity and sediment sizes through a two-year field monitoring program, focusing on the frontal, central, and distal sections of four bars along the Elbe River in Czechia. Despite the absence of high-flow events reaching at least a one-year recurrence interval, observable changes in surface heterogeneity and sediment sizes were noted across all bars. However, the changes did not follow a uniform pattern; individual bars and their sections exhibited varying degrees of surface sediment coarsening or fining, alongside increases or decreases in surface heterogeneity. These findings highlight the necessity for site-specific management strategies for individual bars within such human-impacted rivers, recognizing their value as ecological hotspots. Furthermore, the methodology presented in this study may serve as a blueprint for the cost-effective monitoring of bar dynamics in channelized river sections.

Assessment of polychaete diversity in selected tropical Islands and estuaries on the Southeast coast of India

Increased anthropogenic pressure on the marine environment leads to severe threats to resident biota, a global concern. The Gulf of Mannar (GoM) and Palk Bay (PB) on the Southeast coast of India are two notable ecological hotspots. However, increased industrialization, tourism, and fishing activities in recent years have contaminated the environment and biota of these two ecologically significant coastal zones. This study aims at the impact of seasonal dynamics on polychaete assemblages in four coastal areas (Kanyakumari, Thoothukudi, Ramanathapuram, and Cuddalore) along the southeast coast with different seasons (post-monsoon, summer, pre-monsoon, and monsoon). In all the collected parameters, salinity is the prime variable influencing the distribution of polychaetes greatly; they link to other environmental parameters. Results revealed that temperature, pH, chlorophyll, and total organic carbon all exhibited a strong positive correlation with salinity; others showed a negative correlation. According to a one-way ANOVA, the Kruskal-Wallis test and Pearson correlation have significant differences at the spatial scale (p<0.05). Overall, the multivariate analysis of PCA and CCA, followed by indices like Shannon diversity index and AMBI and M-AMBI indices results, revealed that spatial heterogeneity of the polychaetes was influenced by salinity, temperature, pH, DO, TN, TP, TOC, and clay (p<0.05). The environmental changes and anthropogenic activities are the reason for the spatial variation in the polychaetes.

Deep-sea benthic structures and substrate types influence the distribution of functional groups in the Wallaby-Zenith Fracture Zone (East Indian Ocean)

Three-dimensional deep-sea structures enhance substrate complexity and can shape numerous ecological hotspots that play critical roles in the diversity and distribution of benthic faunal assemblages. The characteristics of these features are not fully understood due to the logistical challenges of exploring at great depths and remote locations. One such deep-sea feature, the Wallaby-Zenith Fracture Zone (WZFZ) located in the East Indian Ocean, was mapped using a full-ocean depth multibeam echosounder system. Additionally, twelve baited landers and five crewed submersible dives were conducted in water depths between 4709 and 6591 m. We use seafloor bathymetry, bathymetric derivatives and video footage from the submersible dives to characterise the benthic structures, substrate types, habitat diversity, and the distribution of associated functional groups of megafauna for the WZFZ. The Benthic Terrain Modeler toolbox was used as an initial semi-automated step to generate benthic structural classes, which were further characterized through the inclusion of bottom salinity and temperature data collected by the scientific landers and integrated with the observations of seafloor substrate from the submersible video footage. This resulted in identification of nine benthic habitat classes characterised by unique seafloor morphological structure and substrate texture. A polymetallic nodule field, a possible extension of the previously reported Cape Leeuwen nodule field, was also observed along submersible transects conducted on the slopes of the WZFZ. The distribution and diversity of the functional megafauna groups observed are influenced by the deep-sea benthic habitats, defined by seafloor structures and substrate heterogeneity, especially the presence of hard substrates such as outcropping bedrock and polymetallic nodules within the WZFZ.

Spatio-temporal Landuse/Landcover Dynamics in the Coastal Areas of Limbe and Douala IV Municipalities and Implications on Wetland Regulating Ecosystem Services

Globally, wetlands are ecological hot spots and as a result they supply a plethora provisioning, regulating, supporting and cultural services. Despite their functions, wetlands continue to degrade arising from urban developments (population growth and housing developments, road infrastructural developments, urban agricultures and usage of wetlands as dumpsites). These activities operate via land use/land cover changes at different scales in different areas depending on technology and needs of the population. This paper describes the implications of spatio-temporal land use/ land cover (LULC) dynamics in the Limbe I and III Municipality (L1&amp;3Ms) and Douala IV Municipality (D4M) coastal areas from 1986 to 2022 on wetland ecosystem services. This research made use of Geographic Information System (GIS) technique in describing the land use/cover changes in the study areas. Primary data was obtained through field observations, questionnaires and ground truthing aim at confirming the observations on downloaded satellite imageries. Four Satellite images of different years (1986, 1999, 2013 and 2022) were downloaded from the United State Geologic Survey (USGS) Earth Explorer. Images were imported into Erdas Imagine, 2014 where preprocessing was done and Supervised Classification was adopted for the processing of the image to generate a raster format depicting the designed land cover/land uses; especially the wetlands which constituted one of the themes. Maps were generated to show changes in land use/cover which were transposed into tables and figures to show the trends in magnitude of changes, percentage of change and the rate of change. Within 36 years (1986-2022) built-up increased by 0.75km2 (0.36%) and 1.63km2 (0.45%) while wetlands retreated by -0.2km2 (-.96%) and -0.48km2 (-0.14%) in L1&amp;3M and D4M respectively. Annually, wetlands decreased by - 97.04km2 and -191.54km2 while settlements/infrastructures increased by 294.33km2 and 644.46km2 over the same 36 year periods in L1&amp;3Ms and D4M respectively. Base on wetland regulating services, changes in LULC has exposes neighbourhoods in L1&amp;3Ms to flood vulnerability comprising the vulnerable, less vulnerable, least vulnerable and most vulnerable areas as opposed to two categories of neighbourhoods in D4M (most vulnerable neighbourhood’s and the less vulnerable neighbourhoods). Information on changes in land use-land cover is crucial in delineating impacted areas, understand the type of changes, their spatial patterns and the need for formulating proper urban planning and environmental preservation policies as well as updating these policies with time. GIS analysis of 1986, 1999, 2013, and 2022, indicated that, there have been significant modifications in observed LULC classes (forest cover, farmland and built-up land uses) over L1&amp;3Ms and D4M.

Implementation of the Pelagic Hotspot Index in detecting the habitat suitability area for bigeye tuna (Thunnus obesus) in the eastern Indian Ocean

Abstract. Istnaeni ZD, Gaol JL, Zainuddin M, Fitrianah D. 2023. Implementation of the Pelagic Hotspot Index in detecting the habitat suitability area for bigeye tuna (Thunnus obesus) in the eastern Indian Ocean. Biodiversitas 24: 5044-5056. Bigeye tuna (Thunnus obesus Lowe, 1839) is a species with a high economic value that can migrate horizontally and vertically over a large area. Although sea temperature has been the main focus of previous findings, other variables can serve as a reasonable proxy. Here we used sea surface chlorophyll-a, sea surface height, subsurface sea salinity, and subsurface temperature to predict the suitable habitat area for bigeye tuna in the Eastern Indian Ocean Off Java. A Generalized Additive Model was performed to analyze the best-fit model evaluated from the p-value and Cumulative Deviance Explained. The suitability index of the selected model was calculated using Pelagic Hotspot Index constructed from multi-spectrum satellite data. The results showed that the high catches were located on the high suitable index value and supported by chlorophyll-a as the most significant factor, followed by sea surface height, temperature, and salinity. This condition was stimulated by the high feeding opportunity, which may relate to the EIO's oceanic front, eddies, and specific current patterns. This study helps identify ecological hotspots, track the migration, and monitor the seasonal closure for bigeye tuna, particularly in EIO.

Ecological risk assessment and management for riverfront development along the Yangtze River in Jiangsu Province, China

The riverfront along large rivers, representing the water–land and human–nature interaction zone, is of great importance for economic and social development and eco-environmental protection. Human activities, such as urbanization and industrialization, together with inadequate urban planning and disorderly development, can result in serious ecological risks to riverfront ecosystems. The focus of this study was the riverfront along the Yangtze River in Jiangsu province, an area experiencing conflicting demands in terms of ecological protection and economic development. We identified the ecological problems and risks at different spatial scales (micro, meso, and macro) and, based on PSR model, construct an ecological risk assessment index system for any further development along the Yangtze River. Ecological hot spots and cluster zones were identified based on Getis-Ord Gi* hot spot analysis and Ward’s hierarchical clustering. The results showed that the ecological risk index at micro scale of the study area presented spatially positive correlation, with hot spots mainly concentrated in municipal districts. The hot spots of ecological risk assessment at the meso-scale are distributed in the estuary around the Yangtze River, and the cold spots are distributed on the Yang-Tai plain. According to the assessment indices of social economy, ecological function, and planning response at the macro scale, the study area could be divided into four clusters. Lastly, a spatial division of ecological risk posed by riverfront development along the Yangtze River in Jiangsu Province was constructed. On the basis of this analysis, we propose suitable risk management and resource protection measures.

RIPARIANET - Prioritising riparian ecotones to sustain and connect multiple biodiversity and functional components in river networks

Europe has committed to upscale ecosystems protection to include 30% of land and sea. However, due to historical overexploitation of natural assets, the available area for biodiversity protection is severely limited. Riparian zones are natural ecotones between aquatic and terrestrial ecosystems, contributing disproportionately to regional biodiversity and providing multiple ecosystem functions and services. Due to this and their branching geometry, riparian networks form a vast system of ‘blue-green arteries’ which physically and functionally connect multiple ecosystems over elevation gradients, despite covering a relatively small area of the basin. Hence, RIPARIANET argues that developing approaches able to optimise the spatial conservation of natural stream-riparian networks represent a flagship example of biodiversity protection in the EU. Although the integrity of riparian zones is fundamental for the achievement of multiple EU environmental objectives, the lack of a standardised framework for biodiversity assessment and protection across Member States has led to extensive impairment of riparian areas and frequent stakeholder conflicts. The main objective of RIPARIANET is to leverage the increasing resolution of remote sensing information to provide practitioners with evidence-based guidance and approaches to biodiversity conservation. Key questions include: i) how can we remotely assess riparian integrity and identify areas which provide effective connectivity allowing species biodiversity and ecosystem functions to persist through meta-ecological processes? ii) how can we disentangle the influence of local- and network-scale stressors and processes on riparian biodiversity to better implement river basin management schemes? iii) to what extent do currently existing protected areas in rivers account for the geometry of riparian networks and their multifunctionality? We will address these questions in riparian networks within six river basins in Europe, including Boreal, Continental, Alpine, Temperate and Mediterranean systems. First, we will gather local needs and interests from key stakeholders together with satellite imagery and GIS environmental data for all basins. Then, riparian and river ecosystems functions will be modelled and ecological hotspots will be identified through a GIS-based multi-criteria approach, including stakeholder inputs. Then, we will collect in situ data to assess multiple biodiversity and stressors at the local scale and, subsequently, scale-up this information to the network scale using geostatistical tools and advanced modelling. This knowledge will be conveyed to managers at local and EU scales in the form of decision-support tools allowing decision-makers to identify protection gaps and ecological hotspots along riparian networks, based on multiple biodiversity, functional and connectivity criteria.

Patchy indirect effects of predation: predators contribute to landscape heterogeneity and ecosystem function via localized pathways

Predators are widely recognized for their irreplaceable roles in influencing the abundance and traits of lower trophic levels. Predators also have irreplaceable roles in shaping community interactions and ecological processes via highly localized pathways (i.e. effects with well‐defined and measurable spatio–temporal boundaries), irrespective of their influence on prey density or behavior. We synthesized empirical and theoretical research describing how predators – particularly medium‐ and large‐sized carnivores – have indirect ecological effects confined to discrete landscape patches, processes we have termed ‘patchy indirect effects (PIEs) of predation'. Predators generate PIEs via three main localized pathways: generating and distributing prey carcasses, creating ecological hotspots by concentrating nutrients derived from prey, and killing ecosystem engineers that create patches. In each pathway, the indirect effects are limited to discrete areas with measurable spatial and temporal boundaries (i.e. patches). Our synthesis reveals the diverse and complex ways that predators indirectly affect other species via patches, ranging from mediating scavenger interactions to influencing parasite/disease transmission risk, and from altering ecosystem biogeochemistry to facilitating local biodiversity. We provide basic guidelines on how these effects can be quantified at the patch and landscape scales, and discuss how predator‐mediated patches ultimately contribute to landscape heterogeneity and ecosystem functioning. Whereas density‐ and trait‐mediated indirect effects of predation generally occur through population‐scale changes, PIEs of predation occur through individual‐ and patch‐level pathways. Our synthesis provides a more holistic view of the functional role of predation in ecosystems by addressing how predators create patchy landscapes via localized pathways, in addition to influencing the abundance and behavior of lower trophic levels.

Sub-frontal niches of plankton communities driven by transport and trophic interactions at ocean fronts

Abstract. Observations and theory have suggested that ocean fronts are ecological hotspots, associated with higher diversity and biomass across many trophic levels. The hypothesis that these hotspots are driven by frontal nutrient injections is seemingly supported by the frequent observation of opportunistic diatoms at fronts, but the behavior of the rest of the plankton community is largely unknown. Here we investigate the organization of planktonic communities across fronts by analyzing eight high-resolution transects in the California Current Ecosystem containing extensive data for 24 groups of bacteria, phytoplankton, and zooplankton. We find that a distinct frontal plankton community characterized by enhanced biomass of not only diatoms and copepods but many other groups of plankton such as chaetognaths, rhizarians, and appendicularians emerges over most fronts. Importantly, we find spatial variability at a finer scale (typically 1–5 km) than the width of the front itself (typically 10–30 km) with peaks of different plankton taxa at different locations across the width of a front. Our results suggest that multiple processes, including horizontal stirring and biotic interactions, are responsible for creating this fine-scale patchiness.

Can Bengal Tiger (Panthera tigris tigris) endure the future climate and land use change scenario in the East Himalayan Region? Perspective from a multiple model framework.

Large mammals are susceptible to land use and climate change, unless they are safeguarded within large, protected areas. It is crucial to comprehend the effects of these changes on mammals to develop a conservation plan. We identified ecological hotspots that can sustain an ecosystem for the endangered Bengal tiger (Panthera tigris tigris), an umbrella species. We developed three distinct ensemble species distribution models (SDMs) for the Bengal tiger in the Indian East Himalayan Region (IEHR). The first model served as the baseline and considered habitat type, climate, land cover, and anthropogenic threats. The second model focused on climate, land use, and anthropogenic threats, the third model focused on climate variables. We projected the second and third models onto two future climate scenarios: RCP 4.5 and RCP 8.5. We evaluated the threats possess to protected areas within eco-sensitive zone based on the potential tiger habitat. Finally, we compared the potential habitat with the IUCN tiger range. Our study revealed that the Brahmaputra valley will serve as the primary habitat for tigers in the future. However, considering the projected severe climate scenarios, it is anticipated that tigers will undergo a range shift towards the north and east, especially in high-altitude regions. Very high conservation priority areas, which make up 3.4% of the total area, are predominantly located in the riverine corridor of Assam. High conservation priority areas, which make up 5.5% of total area are located in Assam and Arunachal Pradesh. It is important to note that conservation priority areas outside of protected areas pose a greater threat to tigers. We recommend reassessing the IUCN Red List's assigned range map for tigers in the IEHR, as it is over-predicted. Our study has led us to conclude both land use and climate change possess threats to the future habitat of tigers. The outcomes of our study will provide crucial information on identifying habitat hotspots and facilitate appropriate conservation planning efforts.

First description of in situ chlorophyll fluorescence signal within East Antarctic coastal polynyas during fall and winter

Antarctic coastal polynyas are persistent and recurrent regions of open water located between the coast and the drifting pack-ice. In spring, they are the first polar areas to be exposed to light, leading to the development of phytoplankton blooms, making polynyas potential ecological hotspots in sea-ice regions. Knowledge on polynya oceanography and ecology during winter is limited due to their inaccessibility. This study describes i) the first in situ chlorophyll fluorescence signal (a proxy for chlorophyll-a concentration and thus presence of phytoplankton) in polynyas between the end of summer and winter, ii) assesses whether the signal persists through time and iii) identifies its main oceanographic drivers. The dataset comprises 698 profiles of fluorescence, temperature and salinity recorded by southern elephant seals in 2011, 2019-2021 in the Cape-Darnley (CDP;67˚S-69˚E) and Shackleton (SP;66˚S-95˚E) polynyas between February and September. A significant fluorescence signal was observed until April in both polynyas. An additional signal occurring at 130m depth in August within CDP may result from in situ growth of phytoplankton due to potential adaptation to low irradiance or remnant chlorophyll-a that was advected into the polynya. The decrease and deepening of the fluorescence signal from February to August was accompanied by the deepening of the mixed layer depth and a cooling and salinification of the water column in both polynyas. Using Principal Component Analysis as an exploratory tool, we highlighted previously unsuspected drivers of the fluorescence signal within polynyas. CDP shows clear differences in biological and environmental conditions depending on topographic features with higher fluorescence in warmer and saltier waters on the shelf compared with the continental slope. In SP, near the ice-shelf, a significant fluorescence signal in April below the mixed layer (around 130m depth), was associated with fresher and warmer waters. We hypothesize that this signal could result from potential ice-shelf melting from warm water intrusions onto the shelf leading to iron supply necessary to fuel phytoplankton growth. This study supports that Antarctic coastal polynyas may have a key role for polar ecosystems as biologically active areas throughout the season within the sea-ice region despite inter and intra-polynya differences in environmental conditions.

Prospects for deploying microbes against tree-killing beetles (Coleoptera) in Anthropocene

Forests form rich biodiversity hubs that act as large reservoirs of natural carbon. The spatial and temporal heterogeneity of these complex habitats of forest floors provides ecological services of immense socio-economic importance. However, these socio-economic ecological hotspots are incessantly exposed to multifarious abiotic, biotic, and anthropogenic disturbances, amongst which unpredictable forest pest (i.e., bark beetle) outbreak account for the loss of vegetation and microbiome of measurable quantum. The importance of the microbiome in forming an inseparable functional unit of every host and shaping its interaction with other partners has been well realized. Interestingly, forest pests, including bark beetles, are also reported to rely on their endosymbiotic microbial partners to manipulate tree defense machinery. In contrast, the microbiome forming the holobiont of trees also regulates the overall function and fitness of the host and significantly contributes to tackling these challenging situations. Nevertheless, how the holobiont of trees directly or indirectly influence beetle holobiont is still an enigma. The present review shall elaborate on the role of microbial tools in enhancing tree performance and fitness, which helps counter beetle damage. Besides, it shall also emphasize exploiting the role of microorganisms in acting as biocontrol agents in shielding the trees against beetle destruction. The application of endosymbiont-mediated RNA interference (RNAi) in working with two-tier specificity for controlling beetle devastations shall be discussed as new-age technological advances. All explanations are expected to put forth the potential of the microbial toolbox in offering better and more sustainable beetle management strategies in the future.

Identification of wetland conservation and restoration priorities in regions of oil extraction in the Yellow River Delta using circuit theory modelling

Oil exploration fragments coastal wetland habitats, which often leads to biodiversity loss and ecosystem degradation. Assessing the negative effects of oil infrastructures at the landscape scale is critical for practical coastal wetland management and the planning of protected areas (PAs). However, information gaps involving wetland connectivity and oil exploration exist in current conservation, which limit the efficiency of PAs.Here, we used a GIS-based circuit theory model (Circuitscape) and high-resolution remote sensing data to simulate the movement patterns of random species and to elucidate the effects of oil wells on their connective elements in four types of wetlands (mudflat, saline marsh, shrub wetland and forest wetland) in the Yellow River Delta (YRD), China. The effectiveness of the Yellow River Delta Nature Reserve (YRDNR) in protecting wetland connectivity was evaluated. A planning framework to optimize wetland conservation and restoration by Linkage Mapper was then provided to improve the landscape connectivity of oil well-disturbed wetlands in this region.The results showed that oil wells significantly decreased wetland connectivity and altered their connective elements in the four wetlands of the YRD. Both the resistance of wetland species movement and the heterogeneity of species dispersal have increased. The length of potential corridors and areas possessing barriers to movement have increased by 126 km (20%) and 51 km2 (120%), respectively. Areas with pinch points that promote species movements, however, decreased by 1178 km2 (60%). The YRDNR protected less than 50% of the key corridors and ecological nodes, considering the impacts of oil wells. Mudflat is seriously affected by oil wells in the YRDNR. Consequently, new alternative corridors produced by oil wells and pinch areas at high risk of impacts by oil wells have the highest protection priorities, whereas those permeable barrier areas, such as croplands and paddy fields, have the highest restoration priorities. The results also illustrated the importance of rivers and water bodies as potential shelters for wetland species.Our research suggests that circuit theory model is an effective planning tool to quantify the negative impacts of oil activities and to identify the protection or restoration priorities of ecological hot spots which are unable to be detected by traditional PAs method. This work provides guides for improving landscape connectivity and specifying target habitats for coastal conservation management.

The Distribution of Surface Soil Moisture over Space and Time in Eastern Taylor Valley, Antarctica

Available soil moisture is thought to be the limiting factor for most ecosystem processes in the cold polar desert of the McMurdo Dry Valleys (MDVs) of Antarctica. Previous studies have shown that microfauna throughout the MDVs are capable of biological activity when sufficient soil moisture is available (~2–10% gravimetric water content), but few studies have attempted to quantify the distribution, abundance, and frequency of soil moisture on scales beyond that of traditional field work or local field investigations. In this study, we present our work to quantify the soil moisture content of soils throughout the Fryxell basin using multispectral satellite remote sensing techniques. Our efforts demonstrate that ecologically relevant abundances of liquid water are common across the landscape throughout the austral summer. On average, the Fryxell basin of Taylor Valley is modeled as containing 1.5 ± 0.5% gravimetric water content (GWC) across its non-fluvial landscape with ~23% of the landscape experiencing an average GWC &gt; 2% throughout the study period, which is the observed limit of soil nematode activity. These results indicate that liquid water in the soils of the MDVs may be more abundant than previously thought, and that the distribution and availability of liquid water is dependent on both soil properties and the distribution of water sources. These results can also help to identify ecological hotspots in the harsh polar Antarctic environment and serve as a baseline for detecting future changes in the soil hydrological regime.

Snowmelt contribution to Arctic first-year ice ridge mass balance and rapid consolidation during summer melt

Sea ice ridges are one of the most under-sampled and poorly understood components of the Arctic sea ice system. Yet, ridges play a crucial role in the sea ice mass balance and have been identified as ecological hotspots for ice-associated flora and fauna in the Arctic. To better understand the mass balance of sea ice ridges, we drilled and sampled two different first-year ice (FYI) ridges in June–July 2020 during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC). Ice cores were cut into 5 cm sections, melted, then analyzed for salinity and oxygen (δ18O) isotope composition. Combined with isotope data of snow samples, we used a mixing model to quantify the contribution of snow to the consolidated sea ice ridge mass. Our results demonstrate that snow meltwater is important for summer consolidation and overall ice mass balance of FYI ridges during the melt season, representing 6%–11% of total ridged ice mass or an ice thickness equivalent of 0.37–0.53 m. These findings demonstrate that snowmelt contributes to consolidation of FYI ridges and is a mechanism resulting in a relative increase of sea ice volume in summer. This mechanism can also affect the mechanical strength and survivability of ridges, but also contribute to reduction of the habitable space and light levels within FYI ridges. We proposed a combination of two pathways for the transport of snow meltwater and incorporation into ridge keels: percolation downward through the ridge and/or lateral transport from the under-ice meltwater layer. Whether only one pathway or a combination of both pathways is most likely remains unclear based on our observations, warranting further research on ridge morphology.

The influence of extreme water levels on coastal wetland extent across the Laurentian Great Lakes

Laurentian Great Lakes coastal wetlands (GLCW) are ecological hotspots and their integrity depends upon dynamic hydrologic regimes of the Great Lakes. GLCW naturally adjust to changes in hydrologic regimes via migration, but Great Lakes water levels may be shifting faster than wetlands can manage: 2000–2015 marked an extended low water level period and was followed by record highs in 2017–2020. Our objective was to quantify how Great Lakes water levels impact GLCW linear extent (from the shoreline to open water). We calculated wetland extent and migration from 2011 to 2019 using data from 1538 vegetation transects at 342 sites across the U.S. shoreline of the Great Lakes. Mediated multiple linear regression with Bayesian hierarchical modeling investigated the relationship between water levels and wetland extent. We employed Bayesian hierarchical modeling because (1) the dataset was spatially nested, with sampling points within wetlands within Great Lakes and (2) Bayesian statistics offer flexibility for environmental modeling, such as the inclusion of mediation in models, where we can assess both direct influences of Great Lake water levels on wetland extent and indirect (i.e., mediated) influences of water levels via the presence of vegetation zones on thus wetland extent. Results showed that, overall, there was a landward migration from 2011 to 2019 (although 38 % of wetlands had lakeward migration of the wetland-upland border). Wetland length and inundation length decreased with increased water levels, as mediated by the presence of certain vegetation zones. This decrease in wetland extent is of concern because it likely relates to a decrease in wetland function and habitat. A better understanding of how GLCW migrate with shifts in water levels enables decision makers to better predict where Great Lakes coastal wetlands are at risk of being lost and thus where to prioritize management efforts.

Integrating biodiversity and ecosystem services to identify ecological priorities for an ecologically fragile city in China

AbstractA high rate of urbanization comes with high environmental costs, leading to reductions in biodiversity and ecosystem services (BES). How to maximize the efficiency and representation of BES in cities is of utmost urgency. However, in the process of spatial prioritization identification, it remains unclear whether a preference for ecosystem services (ES) promotes or detracts from biodiversity. In this study, a Marxan‐based spatial conservation prioritization framework is provided to achieve a win–win situation for ES provision and biodiversity protection. Using Hohhot city, China as a study case, it sets up different weighting scenarios with species and five ES to determine the optimal protected area network for each possible combination. At the same time, it tests the conservation costs, protected features, and spatial overlap of different scenarios with existing protected areas to quantify their conservation efficiency. We found that (1) closed deciduous broadleaved forests, closed evergreen needle‐leaved forests, and deciduous shrublands could support both high biodiversity and abundant ES at altitudes of 1600–2000 m. (2) Although a positive association is found between ES and biodiversity, there is some spatial variation. The geographical overlap rate with biodiversity prioritization was only 29.72% when only ES were considered. (3) Conservation of ecological hotspots by increasing the weight of ES can reduce conservation expenses by 0.69%–20.32% compared to meeting solely biodiversity targets. Our analyses highlight the need for an appropriate weighting of ES in decisions seeking to identify protected areas. This study provides methodological support for the integration of ES and biodiversity, facilitating more comprehensive conservation planning decisions.