Changes In Habitat Conditions Research Articles

Response of species dominance and niche of plant community to wetland degradation along alpine lake riparian.

Alpine wetland degradation threatens riparian biodiversity and ecological balance. Our study, conducted in July 2020 along the northern and eastern shores of Qinghai Lake, seeks to unravel the impacts of such degradation on plant species dominance and ecological niches, using advanced network analysis methods to explore the dynamics and survival strategies of plant species. We applied a space-to-time method to delineate three wetland degradation stage: a healthy swamp wetland, a slightly degraded wet meadow, and a degraded dry meadow. Six representative sampling points were chosen. At each point, three sample lines were randomly established, radiating outward from the center of the lake wetland, with each stage of degradation meticulously examined through three replicates to assess the plant communities in terms of species composition, plant height, coverage, and abundance. The results indicated: Species such as Kobresia tibetica and Leymus secalinus exhibit remarkable abundance across various stages of wetland degradation, indicating a robust tolerance to these conditions. This observation, coupled with the complexity of plant community structures in degrading wetlands, suggests that such intricacy cannot be solely attributed to the dominance of particular species. Instead, it is the result of a diverse array of species adapting to fluctuating water levels, which promotes increased species richness. Despite the prominence of species that exhibit rapid growth and reproduction, the ecological significance of less abundant species in contributing to the community's complexity is also notable. Changes in habitat conditions due to wetland degradation facilitate both competitive and cooperative interactions among species, highlighting the dynamic nature of these ecosystems. Our analysis shows no significant linear relationship between the ecological niche overlap values and niche widths of plant species. However, the strategies employed by dominant species for competition and resource acquisition, as observed in the ecological niche overlap networks, underscore the adaptive capacity of plant communities. These insights underscore the need for tailored restoration strategies to conserve the biodiversity of alpine lake riparian ecosystems. This research not only sheds light on the resilience and adaptability of ecosystems in the Qinghai-Tibetan Plateau but also offers valuable lessons for the conservation of similar habitats worldwide. Our findings underscore the need for tailored restoration strategies to conserve the biodiversity of alpine lake riparian ecosystems. This research not only sheds light on the resilience and adaptability of ecosystems in the Qinghai-Tibetan Plateau but also offers valuable lessons for the conservation of similar habitats worldwide.

Azov sea fishes stock assessment by swept area method through bootstrap

Recently driven changes in habitat conditions in the Azov Sea make classic applications of swept area method inconsistent. Swept area stock assessment method modification for stock estimation of aquatic biological resources through nonparametric bootstrap is presented. New approach is tested against classic calculated results of swept area method for next fish species: Azov anchovy, tulka, turbot and Black-Azov sea shad according to data collected during 2022. Results comparison of classic and modified through bootstrap stock assessment methods leads no significant deviations in mean value estimation. Maximum difference between mean estimates of stock size was 3,75%. Confidential intervals width difference between reviewed methods, in general, was not significant. Most valuable difference in confidential intervals was detected in BCa approach against classic method with quantile approach (due to methodological features of BCa in bias correction procedure). The new stock assessment approach for swept area method though bootstrap permit to calculate statistically valid estimates, their confidential intervals and perform input data validation. The absence of significant differences in the results by the classical and proposed methods indicates the further applicable possibility of classic method even in normality violation in source samples. The normality requirements in methodology of classic approach, probably, is redundant.

The state of stocks and catches of commercial fish species of the Azov and Black Seas for the period 2000–2020: dynamics and trends

The aim to review the state of stocks and fishing against the background of changes in habitat conditions, commercial fish species of the Azov and Black Seas for the period 2000–2020.Materials: Regular scientific research, including: hydrological, hydrochemical, hydrobiological studies, bottom trawl and pelagic lamparian ichthyological surveys; collection and analysis of commercial biological information; analysis of commercial statistical data.Novelty: The dynamics of the values and state of stocks of commercial fish species in the conditions of climate change is shown. In the Black Sea, the increase in the average temperature of the mixed layer, the deepening of the upper boundary of the thermocline in the summer, as well as the slowdown in the cooling of the sea in the autumn-winter period has a negative impact on the productivity of the boreal ichthyofauna and the sprat (sprat) fishery; changes the timing and intensity of migrations of some species of the Mediterranean ichthyofauna, their wintering sites, areas of formation of commercial clusters and, accordingly, the effectiveness of fishing. In the Sea of Azov, the increase in salinity caused by a steady reduction in the volume of freshwater runoff of the Don and Kuban rivers and its replacement by advection of the Black Sea waters is the most important abiotic factor in changing habitat conditions. The increase in the salinity of the Sea of Azov has led to the transformation of traditional hydro- and ichthyocenoses. The gradual transition of the Sea of Azov under the jurisdiction of the Russian Federation makes it possible to more effectively apply resource-saving and resource-restoring measures in order to develop the fisheries potential of this inland sea.As results: the results obtained in this work on the assessment of the impact of anthropogenic and climatic changes will be used to clarify the projected production (catch) of commercial fish.

Rhizosphere assembly alters along a chronosequence in the Hallstätter glacier forefield (Dachstein, Austria).

Rhizosphere microbiome assembly is essential for plant health, but the temporal dimension of this process remains unexplored. We used a chronosequence of 150 years of the retreating Hallstätter glacier (Dachstein, Austria) to disentangle this exemplarily for the rhizosphere of three pioneer alpine plants. Time of deglaciation was an important factor shaping the rhizosphere microbiome. Microbiome functions, i.e. nutrient uptake and stress protection, were carried out by ubiquitous and cosmopolitan bacteria. The rhizosphere succession along the chronosequence was characterized by decreasing microbial richness but increasing specificity of the plant-associated bacterial community. Environmental selection is a critical factor in shaping the ecosystem, particularly in terms of plant-driven recruitment from the available edaphic pool. A higher rhizosphere microbial richness during early succession compared to late succession can be explained by the occurrence of cold-acclimated bacteria recruited from the surrounding soils. These taxa might be sensitive to changing habitat conditions that occurred at the later stages. A stronger influence of the plant host on the rhizosphere microbiome assembly was observed with increased time since deglaciation. Overall, this study indicated that well-adapted, ubiquitous microbes potentially support pioneer plants to colonize new ecosystems, while plant-specific microbes may be associated with the long-term establishment of their hosts.

Click-click, who’s there? Acoustically derived estimates of sperm whale size distribution off western Ireland

Understanding the structure of populations is a critical element to the establishment of management and conservation measures. Sperm whales Physeter macrocephalus are characterised by a demographic spatial segregation, associated with a conspicuous sexual dimorphism reflected in their vocalisations. These characteristics make acoustic techniques very relevant to the study of sperm whale population structure, especially in remote, challenging environments. The reliability of using inter-pulse intervals of sperm whale clicks to infer body size has long been verified and extensively used. We provide the first size structure estimates of the sperm whale population in an area where assumptions on population structure mainly relied on sparse observations at sea, whaling records and stranding data. Over 10,000 hours of acoustic data collected using both static acoustic recorders and towed hydrophone arrays in Irish offshore waters were processed using a machine learning-based tool aimed at automatically extracting inter-pulse intervals from sperm whale recordings. Our analyses suggested that, unlike previously thought, large males would not account for the majority of the animals recorded in the area. We showed that adult females/juvenile males (length 9-12 m) were predominant, accounting for 49% (n = 788) of the number of individuals recorded (n = 1,595), while the proportions of immature individuals (length<9 m) and adult males (length >12 m) were well balanced, accounting for 25% (n = 394) and 26% (n = 413) of the recorded whales, respectively. Our data also suggested some size segregation may be occurring within the area, with smaller individuals to the south. The implications of such findings are crucial to the management of the population and provide an important baseline to monitor changes in population structure, particularly relevant under changing habitat conditions.

Exploratory and seasonal movements of adult common shelducks in the eastern Wadden Sea

Habitat conditions surrounding individual birds are key components determining their fitness, notably by influencing effective foraging, escape from predators, and adaptation to changing environmental conditions. Birds living in dynamic habitats are particularly likely to have a high need to explore; however, spatial and temporal patterns of exploratory movements are poorly understood. We investigated the exploratory movements of adult common shelducks (hereafter Shelducks, Tadorna tadorna) in the Wadden Sea, which provides a dynamic habitat for birds. We captured nine shelducks in adjacent breeding areas and attached GPS satellite telemetry devices for 5–18 months, mostly covering the post-breeding period. We analyzed bird-movement patterns based on mean daily locations and behavioral change point analysis. All individuals explored on a median of 22% of tracking days (range = 6–39%). Individuals usually explored new areas for a short time before switching to stay in these areas for longer periods. Exploratory movements were particularly frequent before the start of the flightless period during molting. During this time, shelducks explored the traditional molting area in the Elbe estuary intensively. However, birds did not explore places within the area subsequently used for molting for longer or more often than other places. The molting area was used for a median of 59 days, i.e., about twice as long as required for the flightless period, suggesting that this area was explored not only to select a suitable molting place, but also for other purposes. Only two shelducks performed longer-distance exploration movements, i.e., > 45 km from their sedentary areas. We therefore concluded that exploratory movements by adult shelducks may enable the birds to adapt to small-scale changes in habitat conditions.

Assessment of the influence of abiotic environmental factors on the distribution of bream and carp in the Northern Caspian

Changing habitat conditions is an important driving force affecting the distribution of fish in the range. A quantitative assessment was made of the influence of environmental factors on the distribution of bream Abramis brama Linnaeus, 1758 and carp Cyprinus carpio Linnaeus, 1758 in the waters of the eastern part of the Northern Caspian. The number was estimated based on the results of research net catches. The preferred temperatures and habitat depths of bream and carp in the shallow zone of the Northern Caspian are shown. The colleof field material was carried out during complex expedition observations in 2014 and 2020. The installation of nets with a mesh of 30–200 mm was carried out in the shallow-water zone of the eastern part of the Northern Caspian. Bream and carp in the Northern Caspian Sea form concentrations in areas with depths up to 6–8 m. In the time interval from the end of April to October, bream was observed in the temperature range from 7.0 to 28.5 °C, carp — from 5.5 to 28.0 °C. A mathematical assessment of the influence of depth, temperature and water transparency on the number of these fish species was carried out. The obtained regression models took into account from 44.9 to 80.1% of the factors determining the number of fish in the studied water area. Carp are more sensitive to the effects of temperature, depth and transparency compared to bream. The obtained results provide a theoretical basis for predicting changes in the habitat of fish due to abiotic environmental factors, which is relevant in connection with pronounced climatic changes

Macroinvertebrate Spatial Diversity Patterns of Shore Habitats in Italian High-Altitude Natural and Permanent Lakes and Ponds

A comparative analysis of environmental conditions between Alpine and Apennine lakes/ponds which represent different faces of European mountain regions was conducted. The data set was created on the basis of previous works carried out by national and international institutions including biological, physical–chemical, geographic, and precipitation data from 27 lakes/ponds placed at altitudes ranging from 2334 ± 294 m a.s.l. (in the Alps) and 1541 ± 154 m a.s.l. (in the Apennines), with mean maximum depths of about 5.5 ± 4.6 m. A specific focus was dedicated to chironomids as outstanding sentinels for local and global changes in habitat conditions. Species richness and Taxonomic Distinctness Indices were applied to lakes/ponds macroinvertebrates to highlight differences in the biodiversity of the two areas. Subsequently, associations between descriptors of the mountain region climate, lithology, water chemistry, lake morphology, geography, macroinvertebrate assemblage richness, and distinctness were examined through Principal Component Analysis, Analysis of Variance, and Non-metric Multi-dimensional Scaling. Results showed strong positive correlations between mean annual precipitation and temperature with lake macroinvertebrate biodiversity as a whole and with chironomid in particular. Thus, these shore habitats face a threat under climate change conditions (impacting thermal and precipitation regimes). These results are also central in showing that even small ecosystems are important sources of biodiversity for the lower altitudes, stressing the urgency of including them within targeted monitoring and action plans to preserve their peculiar habitat, flora, and fauna.

The Effect of Peatland Restoration on Ciliate Communities: Long-Term Analyses

Peatlands are extremely valuable ecosystems of enormous biological diversity, mainly due to their specific geological and hydrological conditions. One of the most important threats facing these habitats is overgrowth resulting from intensifying succession processes. Due to the fact that peatlands are endangered or vanishing, attempts are made to restore their original natural assets. The aim of the present study was to determine the effect of active conservation of peatland ecosystems, in the form of removal of birch trees, on communities of ciliates. The subject of the research was the Durne Bagno peat bog, located in Polesie National Park in eastern Poland. Analysis of the results of long-term research (nine years) showed that active conservation measures affect the physical, chemical, and hydrological properties of peatlands. In the habitat where birch trees were cut down, the water level, temperature, and chlorophyll a concentration in the vast majority of cases were higher than in the area with Betula L. Changes in habitat conditions are reflected in the taxonomic composition and abundance of ciliates. In the habitat from which birch trees were removed, ciliate abundance was higher than in areas where birch remained. The total number of taxa in the habitats was the same, but there were seasonal differences. The most taxa were recorded in spring and summer and the fewest in autumn. Thus, analysis of the results indicates that ciliates are an appropriate indicator group of species for biomonitoring of peatland restoration.

Physiological aspects of selected indicator species of undergrowth of old forests

The study concerns the study of selected physiological features of three indicator species of the undergrowth of the oak-hornbeam forest (Anemone nemorosa L., Galeobdolon luteum Huds. emend. Holub and Stellaria holostea L.), after the forest canopy closure. Las Wolski, an isolated forest complex located within the city of Cracow (Southern Poland), was selected for the study. The plant material was collected at two points in the season – right after the forest canopy closure and a month later. Under laboratory conditions, the physiological characteristics of the indicator species were analysed. Light stress may play a smaller role here, and physiological parameters are probably most affected by the phenology of undergrowth species, which is adapted to seasonal changes in habitat conditions. However, these issues require more research.

Evaluating Habitat Suitability and Tidal Wetland Restoration Actions With ECOSTRESS

AbstractAs temperatures rise, it is increasingly important to monitor changes in habitat conditions for aquatic species and mitigate emerging stressors. The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) instrument provides temperature products at a spatial and temporal scale not previously available. Here, we utilize ECOSTRESS temperature products to assess fluctuations in thermal habitat suitability for an endangered fish species and we also demonstrate the utility of the data set to assess water surface and bulk temperature changes following completion of two tidal wetland restoration efforts in the San Francisco Estuary and Sacramento–San Joaquin River Delta (Bay Delta). During all hours of the day throughout the 2018–2022 study period, key Delta Smelt habitat areas including Honker Bay, West Suisun Bay, and Mid Suisun Bay had greater than 75% of their areas suitable; there were several instances during which less than 25% of the area was thermally suitable generally coinciding with heatwave events. Overall, midday hours are less frequently suitable than morning and evening hours. Early evidence from ECOSTRESS indicates that there may be a decrease in surface water temperature of up to several degrees in tidal restoration areas, but more data is needed to show statistically significant outcomes. The ECOSTRESS record began in summer of 2018, and a longer record is needed to fully capture temperature changes associated with wetland processes and restoration efforts. Future applications of ECOSTRESS products can the capacity to help further understand ecosystem conditions and how restoration efforts affect water temperature, informing decisions that benefit Delta Smelt and other at‐risk aquatic species.

Stream Habitats and Aquatic Communities in an Agricultural Watershed: Changes Related to a Mandatory Riparian Buffer Law.

Riparian buffers along streams can intercept eroding soils, contaminants, and nutrients, improving stream habitats and increasing the health of aquatic communities. Instream and riparian habitats and fish and benthic invertebrate communities were surveyed in a Minnesota stream draining an agricultural watershed before and after implementation of a state-mandated buffer law passed in 2014 and aimed at protecting water quality. Intensive habitat assessments, electrofishing, and benthic invertebrate sampling were used at the same 13 sites in 2005 and 2018. Average buffer width nearly doubled between surveys, and instream abundance of fine sediments and embeddedness of coarse substrates by fine sediments both declined significantly within 1 to 3 years of buffer establishment. Stream sites also were significantly deeper with faster current velocities, and sites had increased riffle habitat and increased instream vegetative cover for fish after buffer mandates. However, fish and invertebrate biotic integrity scores, and other biotic community metrics, did not display significant improvements after buffer establishment. Stream habitats appear to improve quickly when intact and continuous riparian buffers insulate streams from surrounding agricultural activities, but improvements in biotic communities likely will require more time to adapt to changed habitat conditions.

Ground beetle (Coleoptera: Carabidae) taxocoenoses from high-altitude Pinus peuce and Pinus heldreichii forests in Bulgaria

The sensitivity of ground beetles to changing habitat conditions makes them a good indicator of environmental change. The shift in their distribution could be used as an early warning signal for natural disturbances due to climate change. To reflect and monitor these changes, initial information is needed on carabid taxa in different high-altitude habitats, including the endemic and climate-sensitive tertiary relict coniferous forests of Pinus peuce (Macedonian pine) and Pinus heldreichii (Bosnian pine). Data on the carabid beetles in the different coniferous habitats in Bulgaria are scattered in various faunistic or taxonomic publications, and there is no exact information about their taxocoenoses in the Macedonian and Bosnian pine habitats. The present study aims to clarify the species composition and diversity patterns of ground beetles in these habitats in Bulgaria. Six sample sites were selected: five natural forest stands in the Rila Mts and Pirin Mts and one forest plantation in the Vitosha Mts. A total of 18 species and subspecies typical of forest habitats were recorded. Five of them were endemic to Bulgaria and five to the Balkan Peninsula. The most common species and the eudominant in the majority of the sample sites was Calathus metallicus aeneus. The exception was one of the Bosnian pine sample sites. Here, the dominant species was Xenion ignitum. The ground beetle species found in the studied forests were mostly zoophagous, mainly crevice or burrowing stratobionts in leaf litter, rocks and soil, a few epigeobionts, one botrobiont and one mixophytophagous geohrotobiont. The classification of the carabid taxocoenoses according to their qualitative composition showed two main clusters: the first being the carabids from the studied sites of the Vitosha and Rila Mts, and the second being the taxocoenoses from the Pirin Mts. The Bosnian pine habitats provide more favourable conditions for the high-altitude ground beetles, where they are in a state of equilibrium with higher species richness and evenness compared to those inhabiting the Macedonian pine forests. The forest communities of Pinus peuce and Pinus heldreichii in Bulgaria are of high conservation importance for the ground beetle and an even higher level of protection of these habitats is required.

Response mechanism of growth and gypenosides content for Gynostemma longipes cultivated at two altitude habitats to fine root morphological characteristics.

Fine roots are the critical functional organs of plants to absorb water and nutrients from the soil environment, while the relation between fine root morphological characteristics and yield & quality has received less attention for medicinal plants. Therefore, we investigated the relationship between fine root morphological characteristics and biomass & gypenosides content. We explored the primary environmental drivers of fine root indicators for Gynostemma longipes from three provenances cultivated at two altitude habitats. At the end of the growing season, compared with the low-altitude habitat, the underground biomass of G. longipes in the high-altitude habitat increased significantly by 200%~290% for all three provenances. The response of gypenosides content to different altitude habitats varied with provenance and plant organs. The biomass of G. longipes strongly depended on the fine root characteristic indicators (P < 0.001), fine root length density, and fine root surface area. Our results also showed that the harvest yield of G. longipes could be effectively increased by promoting the growth of fine roots per unit leaf weight (P < 0.001, R2 = 0.63). Both fine root length density and fine root surface area had strong positive correlations with soil nutrient factors (R2 > 0.55) and a strong negative correlation with soil pH (R2 > 0.48). In a word, the growth of G. longipes is strongly controlled by the fine root morphological characteristics through the response of fine roots to soil nutrient factors and pH. Our findings will help to deepen the understanding of the root ecophysiological basis driven by soil factors for the growth and secondary metabolites formation of G. longipes and other medicinal plants under changing habitat conditions. In future research, we should investigate how environmental factors drive plant morphological characteristics (e.g., fine roots) to affect the growth & quality of medicinal plants over a longer time scale.

Occurrence and patterns of fin whale songs reveal alternative migration strategies in Svalbard Islands, Norway

The Arctic marine environment is highly affected by global warming with notable changes in habitat conditions, which have great consequences on migrating species. For example, the timing of their migration can be altered leading to changes in their occurrence in suitable areas, which are critical for their survival. In this study, seven years of acoustic data were analysed in Svalbard Islands from 2014 to 2020, revealing that the occurrence of fin whales (Balaenoptera physalus) happened all year-round. The sea surface temperature recorded reveals conditions which could be favorable for these species to persist until the Polar Night. The occurrence of songs indicated that certain individuals did not undertake the migratory journey through the southern breeding grounds, possibly using the area for mating purposes. The analyses of the Inter-Note-Interval (INI) demonstrated that over the years songs with different patterns were found. This suggests that either the fin whales are able to switch their INI patterns or that populations with different INIs are visiting during the Winter. Therefore, this study unveils the undertaking of an alternative strategy to migration movements, and the possible potential origin of the fin whales overwintering in Svalbard.

Mechanisms underlying the epipelagic ecosystem response to ENSO in the equatorial Pacific ocean

The El Niño/Southern Oscillation is known to strongly impact marine ecosystems and fisheries. In particular, El Niño years are characterized, among other things, by a decrease in tuna catches in the western Pacific and an increase in the central Pacific, whereas these catches accumulate in the far western Pacific during La Niña conditions. However, the processes driving this zonal shift in the tuna catch (changing habitat conditions, currents or food availability) remain unclear. Here, we use an hindcast simulation from the mechanistic ecosystem model APECOSM that reasonably reproduces the observed zonal shift of the epipelagic community in response to ENSO to understand the mechanisms underlying this shift.Although the response of modeled epipelagic communities to El Niño is relatively similar for the different size classes studied, the processes responsible for these changes vary considerably by organism size. One of the major results of our analysis is the critical role of eastward passive transport by El Niño-related surface current anomalies for all size classes. While the effects of passive transport dominate the effects of growth and predation changes for large organisms, this is not the case for intermediate-sized organisms in the western Pacific, where the decrease in biomass is first explained by increased predation and then decreased foraging success. For small organisms, changes in growth rate, induced by the influence of temperature on fish physiology, is an important process that reinforces the biomass increase induced by passive horizontal transport in the eastern Pacific and the biomass decrease induced by increased predation by intermediate-sized organisms near the dateline. Finally, contrary to what is often assumed, our model shows that active habitat-based movements are not required to explain the westward biomass shifts that are observed during ENSO.This study illustrates the relevance of using a mechanistic ecosystem model to disentangle the role of the different processes controlling biomass changes. It highlights the essential dynamic role of ocean currents in shaping the response of marine communities to climate variability and its interaction with biological (e.g. growth) and ecological (e.g. foraging and predation) processes, whose relative importance varies with organisms’ size and contribute to modify the community structure.

Improved method for benthic ecosystem health assessment by integrating chemical indexes into multiple biological indicator species—A case study of the Baiyangdian Lake, China

A comprehensive and scientific assessment of benthic ecosystem health is key to the rational selection of endogenous pollution reduction technologies for lakes. However, current assessments are mainly limited to biological indicators and ignore the actual benthic ecosystem situations, such as the impact of eutrophication and heavy metal pollution, which may lead to the one-sidedness of the evaluation results. In this study, taking Baiyangdian Lake, the largest shallow mesotrophic-eutrophic lake in the North China Plain, as an example, the chemical assessment index and biological integrity index were first combined to estimate the biological conditions, nutritional status and heavy metal pollution of lakes. The indicator system incorporated three biological assessments (benthic index of biotic integrity (B-IBI), submerged aquatic vegetation index of biological integrity (SAV-IBI) and microbial index of biological integrity (M-IBI)) and three chemical assessments (dissolved oxygen (DO), comprehensive trophic level index (TLI) and index of geoaccumulation (Igeo)). Twenty-three attributes of B-IBI, fourteen attributes of SAV-IBI and twelve attributes of M-IBI were screened by range, responsiveness, and redundancy tests to keep the core metrics that were significantly correlated with disturbance gradients or showed strong discriminatory power between reference and impaired sites. The assessment results of B-IBI, SAV-IBI, and M-IBI showed significant differences in the response to anthropogenic activities and seasonal change, among which the submerged plants showed more significant seasonal differences. It is difficult to reach a comprehensive conclusion regarding the benthic ecosystem health status based on a single biological community. In comparison with biological indicators, the score of chemical indicators is relatively low. DO, TLI and Igeo provide an essential supplement for the benthic ecosystem health assessment of lakes with eutrophication and heavy metal pollution problems. Using the new integrated assessment method, the benthic ecosystem health of Baiyangdian Lake was rated as fair, especially the northern parts of the lake adjacent to the inflow mouth of the Fu River, which were in poor condition, indicating that the lake has experienced anthropogenic disturbance, resulting in eutrophication, heavy metal pollution and biological community degradation. Whether it's spring or summer, the integrated assessment method provides a more plausible and comprehensive view of benthic ecosystem health under the pressure of increasing human activities and changing habitat and hydrological conditions, overcoming the narrow perspective and uncertainties of the single-index method. Thus, it can assist lake managers in providing technical support for ecological indication and restoration.

Changes in habitat conditions in a Late Glacial fluviogenic lake in response to climatic fluctuations (Warta River valley, central Poland)

The Warta River valley was greatly influenced by the ice sheet of the Last Glacial Maximum (LGM). A small peatland located in the Warta drainage system is here used as a palaeoarchive of climatic and habitat changes during the Late Glacial (Weichselian). The Ługi sediment profile was investigated using multi-proxy (pollen, Chironomidae, Cladocera and geochemistry) analyses that recorded changes in a fluviogenic sedimentary depression. After the Poznań Phase (LGM), Ługi functioned as an oxbow lake that was cut off from the active river channel as a result of fluvial erosion. Since that time, the Warta River has flowed only along the section now occupied by the Jeziorsko Reservoir. Sedimentation of lacustrine deposits started at the beginning of the Late Glacial. Summer temperature reconstructions indicate cool Oldest and Younger Dryas, but no clear cooling in the Older Dryas. During the Younger Dryas the palaeolake was completely occupied by a peatland (fen), which periodically dried out during the Holocene. Investigation of this site has tracked the reaction of the habitat to climatic, hydrological and geomorphological changes throughout the Late Weichselian.

The Search for Suitable Habitats for Endangered Species at Their Historical Sites-Conditions for the Success of Salix lapponum and Salix myrtilloides Reintroduction.

Restoring endangered plant species to their historical sites is not always possible due to constantly changing habitat conditions. The aim of this study was to test the effects of reintroduction of two relict willow species in eastern Poland. The experiment consisted of planting 48 individuals of Salix lapponum and S. myrtilloides, obtained by micropropagation, at each of the two selected sites and observing their survival after one year. At the same time, selected physicochemical and biocenotic factors of the environment were monitored. About 70% of S. lapponum individuals and 50% of S. myrtilloides plants survived the one-year period. This result can be considered satisfactory and confirms the effectiveness of this means of active protection. The results of measurements of selected abiotic factors of the environment and the observations and ecological analysis of the flora indicated that the habitat conditions of both historical sites have changed, resulting in accelerated succession of vegetation. However, complete habitat degradation did not occur, although the development of a multi-story structure of one of the phytocenoses intensified competition for light and other environmental resources, which narrowed the potential ecological niche of the reintroduced species.

Dynamic vegetation cover and decline in common eider breeding numbers in Nova Scotia, Canada

The American common eider ( Somateria mollissima dresseri) is a colonially nesting sea duck breeding on islands in the coastal regions of Atlantic Canada. Declines in colony size have been pronounced in some parts of its range, notably in Nova Scotia, and may be attributable to a variety of interconnected factors including changes in habitat conditions. Using surveys collected two decades apart, we compared nesting habitat types, availability, and use by breeding eiders on 16 islands that supported &gt;1600 eider nests in 1992–1993, but 830 nests in 2013. While general patterns of eider nesting habitat use remained consistent (e.g., nesting preferences exhibited for Low Shrubland and Grassland habitats, and avoidance of forest or beach habitats), overall vegetation cover declined, but relative habitat changes were inconsistent across islands. Three of the islands with the greatest change in vegetation had cormorant ( Phalacrocorax spp.) colonies in 2013 that were not there in the earlier years. We suggest that changes in vegetation, in some cases facilitated by cormorant colony formation, influenced susceptibility of nesting females to predators, and these interconnected factors may be contributing to local population declines.