Ecologies

Citizen science is increasingly utilized for environmental monitoring and educational purposes. For lotic ecosystems, this approach could be used to implement traditional methods and gain more data on local biodiversity, particularly in areas where professional monitoring is limited. This study, conducted in Italy, aimed to complement data on river macroinvertebrates collected by the Regional Environmental Protection Agency (ARPA) with additional data gained by volunteers. Our results revealed taxonomic differences between the macroinvertebrate communities of ARPA and citizen science sites. ARPA sites host 34.4% of the total biodiversity, with 22 exclusive taxa, while citizen science sites, with 6 exclusive taxa, represent 9.4% of the total gamma diversity. Compositional differences are mainly explained by taxa turnover between sites. ARPA sites, located along the main river stretches, are richer in alpha and gamma diversity, while volunteer-monitored sites, mostly in agricultural ditches, show lower richness at the local and regional scales but host some unique taxa, increasing the total biodiversity. This study supports the implementation of volunteer programs to increase the number of monitored rivers, enhancing information on macroinvertebrate diversity and distribution and generating relevant data to support decision-making and develop strategies for river conservation and ecosystem restoration at a local scale. Full article

Foliar endophytic fungi (FEF) live within leaves without causing visible signs of disease. FEF occur in all vascular plants, yet the exact nature of interactions between specific FEF and their hosts is not well understood. Some FEF are associated with enhanced water use efficiency, nutrient acquisition, and defense. However, others may have negative effects under high-stress conditions. We examined a series of gas exchange traits in sweet birch (Betula lenta, Fagaceae) along an elevation gradient in the Pisgah National Forest Asheville, North Carolina, USA. From these leaves, we cultured surface-sterilized samples to examine FEF frequency and diversity. FEF cultures were categorized by morphotype and identified through analysis of internal transcribed spacer (ITS) sequences. FEF colonization frequency was 100% across all sites, and we identified 68 distinct morphotypes. Genetic identification of a subset of cultures suggests highly diverse FEF communities within this study system. Leaf gas exchange traits showed significant correlations with elevation at the site level, supporting the hypothesis that water stress increases with increasing elevation. However, further research is needed to determine associations between FEF communities and elevation. These findings, especially considering the limited sample size and small spatial scale of this study, indicate that the southern Appalachians are a promising region for future studies of FEF in forest systems. Full article

Moroccan vegetation faces significant pressure particularly from human activities and climate change, while most ecosystems lack detailed assessments. Phytoecological studies and species assessments are implemented using vegetation sampling, analysis of climate data, geological substrate maps, and the Digital Elevation Model (DEM). The study area hosts 565 plant species distributed into 74 families, with Asteraceae being the most abundant family, representing 17.7%. In addition, the correspondence analysis test demonstrates that species are grouped into six distinct blocks. Block 1 comprises a set of Quercus ilex forests. Block 2 encompasses Juniperus phoenicea lands and transition zones between Quercus ilex and Juniperus phoenicea. Block 3 represents Pinus halepensis forests and pine occurrences within Quercus ilex and Juniperus phoenicea stands. Block 4 indicates the emergence of xerophytic species alongside the aforementioned species; it forms the upper limits of Blocks 1, 2, and 3. Block 5 corresponds to formations dominated by Juniperus thurifera in association with xerophytes. Block 6 groups together a set of xerophytic species characteristic of high mountain environments. Additionally, Quercus ilex colonizes the subhumid zones and prefers limestone substrates, Juniperus phoenicea and Tetraclinis articulata, and Pinus halepensis occupies the hot part of the semi-arid in limestone, clays, and conglomerates, while the Juniperus thurifera and xerophytes inhabit the cold parts and limestone substrates. The thermo-Mediterranean vegetation level occupies low altitudes, dominated by Tetraclinis articulata, Juniperus phoenicea, and Olea europaea. The meso-Mediterranean level extends to intermediate altitudes, dominated by Quercus ilex and Juniperus phoenicea. While the supra-Mediterranean level is dominated by Quercus ilex, Arbutus unedo, and Cistus creticus. The mountain Mediterranean level, located in the high mountains, is dominated by Juniperus thurifera associated with xerophytes. Finally, the oro-Mediterranean level, found at extreme altitudes, is dominated by xerophytes. Some species within this region are endemic, rare, and threatened. Consequently, the implementation of effective conservation and protection policies is recommended. Full article

Pluchea ovalis (Pers.) DC. is an invasive alien plant species. It has spread widely on the island of Tenerife since it was first introduced, becoming a major threat to the island’s flora. The aims of this study are to analyze its germination capacity under different environmental conditions (e.g., light and temperature) and determine its effects on soil properties and native plant communities. Germination assays were carried out both in a germination chamber and in a greenhouse. Twelve plots were also established in the field to determine its effect on soil properties and plant species composition. Our results reveal that the germination capacity of Pluchea ovalis decreases under high temperature ranges and increases on flooded substrates. In addition, Pluchea ovalis can modify soil physicochemical properties by increasing soil magnesium content. As its invasive potential has been demonstrated, this study contributes with evidence of its effects on environmental conditions and species composition. Moreover, we recommend its inclusion in the Spanish Alien Invasive Species Catalogue and the development of further studies about its potential distribution and effects in the Canary Islands. Full article

Catastrophic wind events play important but poorly documented roles in shaping bottomland hardwood forest structure and composition. The objective of this study was to survey a forested wetland area in Illinois, USA, twenty years following a severe tornado (wind speeds ranging from 333–418 km/h). Part of the damaged area had a subsequent salvage logging operation, and we compared the stand structure and composition of these damaged areas to adjacent reference sites. Stem density, basal area, and diversity differed significantly but slightly among disturbance types (p < 0.05). The density of Quercus spp. decreased in regenerated stands, while the density of Fraxinus pennsylvanica and invasive non-native species cover increased (p < 0.05). Salvage logging further increased the density of key bottomland taxa: Salix spp., Taxodium distichum, and Nyssa aquatica, as well as early successional species such as Liriodendron tulipifera (p < 0.05). Productivity did not differ between wind-impacted areas that were logged and not logged (p > 0.05). Recognizing the need for caution when informing management with case studies, this study highlights the value of delaying the assessment of even extreme wind disturbance impacts in hardwood forest recovery until the contribution of crown regrowth of severely wind-damaged trees, along with post-disturbance origin regeneration, can be ascertained. Full article

The widespread distribution of microplastics (MPs) is causing increasing concern among the scientific community and the public. Marine mammals are considered indicators of the ecological health of marine ecosystems, and many species, suffering from numerous anthropogenic factors, have been granted protected status. Pinnipeds (Pinnipedia) are susceptible to ingestion and bioaccumulation of MPs from their environment, through direct consumption and trophic chain transfer. This literature review describes MP exposure for representatives of the three pinniped families—true seals (Phocidae), eared seals (Otariidae), and walruses (Odobenus)—and is based on 26 studies. Data on MP content was reported in scat in 17 articles, in the gastrointestinal tract (GIT) in 8 articles, and in the blubber in 1 article. Plastic material was detected in 22 studies, with its overall occurrence varying from 0 to 100% of samples. In addition to the quantitative assessment of MP content, one study provides data on the correlation between MP levels in animal organisms and pollution biomarkers such as phthalates and porphyrins. The contemporary experience of studying MP ingestion and MP exposure for pinnipeds (Pinnipedia) is discussed step-by-step, focusing on: (1) collection, (2) extraction, and (3) identification methods. This review provides current and collated information on the methods and results of studies concerning MP exposure for pinnipeds (Pinnipedia), which can serve as a guide for future researchers in this area. Full article

The European Turtle Dove (Streptopelia turtur) has experienced significant population declines across its European breeding range, primarily due to habitat loss. Our study aimed to provide a new reference for the conservation of Turtle Doves in Evros province, a biodiversity hotspot. We used Maximum Entropy (MaxEnt) modeling to assess Turtle Dove breeding habitat suitability and account for the area of suitable habitats that is not protected or have been affected by a recent mega-fire. The best performing model identified tree cover density, the percent cover of permanently irrigated land and heterogenous agricultural areas, proximity to non-irrigated agricultural land, and forest edge length as the most important predictors of habitat suitability, signifying the importance of an interplay between open and forested land. Our results indicate that 39% of the study area provides a suitable breeding habitat, with the majority located in central and southeastern regions. Conversely, irrigated agricultural areas in the northeast are unsuitable. We found that more than 60% of suitable habitats fall within the Natura 2000 network, underscoring the importance of protected areas for conservation. However, wildfires pose a major threat, with almost 25% of suitable habitats being affected by a recent mega-fire, highlighting the need for recovery in these areas. Our study provides a foundation for targeted habitat management and restoration efforts in NE Greece and contributes to the broader understanding of the species’ habitat requirements across its breeding range. Full article

Accurately assessing the natural variation in biodiversity is crucial as a baseline for monitoring trends and attributing them to natural or anthropogenic drivers. To assess this baseline, we estimated the species richness, composition and abundance of plants, beetles and ants in Evolution Canyon II (Israel), a protected reserve in the Eastern Mediterranean that is known both for its heterogeneity and for faster-than-average climate change. Consecutive sampling over 24 months in three divergent microhabitats of the canyon (south-facing xeric and north-facing mesic slopes and the valley bottom) during 2019–2021 was conducted using the same methods employed at the same site during 1998–2000, enabling us to also study seasonal and inter-annual variation. Altogether, 459 beetle species, 349 plant species and 47 ant species were found. These taxa exhibit substantial and persistent divergence between canyon slopes. Despite substantial species turnover rates between periods in all the taxa, almost no change was found regarding the biogeographical origins of plant and beetle species composition. In addition, species richness differences between microhabitats persisted between study periods, and year-round sampling revealed many dominant winter-peaking beetle species. These findings reflect the importance of thoroughly surveying diverse taxa, microhabitats, seasons and annual weather patterns when characterizing the natural baseline of a monitoring program. Full article

For the first time, field surveys for exploring the diversity and composition of shallow-water polyplacophorans in West Antarctica have been conducted. During the austral summer sampling campaigns of 2022, 2023 and 2024, a total of 1717 specimens of four species were collected from 21 localities. The composition, abundance, and diversity estimate of the assemblages showed that richness decreased southward due to changes in species composition. The ordination analysis showed a high similarity among localities. Thus, of the seven shallow-water chiton species previously recorded in Antarctica, only four were recorded here. Of them, Tonicina zschaui, Leptochiton kerguelensis, and Hemiarthrum setulosum were the most common and abundant, while Callochiton bouveti was the rarest and least abundant species. The diversity of shallow-water polyplacophorans in this area of Antarctica is low compared to the higher number of species reported in other sub-Antarctic regions. It is suggested that the effect of ice cover on shallow-water habitats could affect the abundance and diversity of chitons. In turn, the high similarity of assemblages may be due to the transport of larvae and juveniles by ocean currents and rafting between the studied sites. Full article

The urbanization and the expansion of human settlements led to the adaptation of many animal species to living close to humans, often using buildings for roosting. Panel buildings are particularly attractive to rock-dwelling animals such as swifts, swallows, pigeons, and bats due to their numerous cracks and crevices. The abundance of these structures in Eastern Europe has led to the establishment of numerous bird and bat colonies in the cities. However, the recent renovation and insulation of these buildings, while beneficial to residents, threatens the roosts. Construction workers are sometimes unaware of animal presence and inadvertently destroy nests or colonies. Rapid assessments before renovation are essential to rescue individuals and ensure the planning of alternative roosts for bats and birds. We conducted a pilot survey of 61 residential buildings in five municipalities in Bulgaria: Razgrad, Popovo, Haskovo, Dimitrovgrad, and Bobov Dol, to assess bird and bat biodiversity. We performed field assessments using direct observation, thermal cameras, ultrasonic detection, sunset counts, and endoscopic cameras. The most commonly detected bird species were the house martin, barn swallow, common swifts, the Eurasian jackdaw, pigeons, and sparrows. The most commonly detected bat species were the common pipistrelle, noctule, and Kuhl’s pipistrelle. Additionally, we discuss the specifics of the “soviet-type” buildings as nesting facilities for pigeons and the impact of the pigeons on the “micro ecology” of the blocks. Our study aimed to guide conservation actions and awareness during the expanding renovation efforts of old buildings in Bulgaria. Full article

The relationships among species and the mechanics of those relationships are very complicated in mixed forests, and allelopathy is one of the most important mediators of these relationships. The types and quantities of allelopathic chemicals are different in coniferous and broadleaved trees; studying the responses of some sensitive plants, such as certain crops, to allelopathy mediated by the leaf extracts of coniferous and broadleaved trees would be an effective technique to evaluate the relationships among species in a mixed forest. In this paper, the effects of leaf extracts from Metasequoia glyptostroboides, Cedrus deodara, Liquidambar formosana, Platanus acerifolia and a mixture of of coniferous and broadleaved trees on seed germination and seedling growth of Sesamum indicum at a constant concentration (50 gDW/L) were investigated using an indoor filter paper culture dish method. The test results were evaluated using the response index (RI) and the synthesis allelopathic effect index (SE). The results showed that: (1) Four kinds of leaf extracts inhibited the germination and seedling growth of S. indicum. The order of the allelopathic inhibitory effects were as follows: L. formosana > M. glyptostroboides > C. deodara > P. acerifolia; (2) In this experiment, the single leaf extract of the coniferous species (M. glyptostroboides and C. deodara) and the single leaf extract of the broadleaved species (L. formosana and P. acerifolia) did not exhibit significant differences in the direction of the allelopathic effect on S. indicum; (3) Compared to their corresponding single leaf extracts, M. glyptostroboides + P. acerifolia and C. deodara + P. acerifolia mixed leaf extracts promoted the allelopathic effects of S. indicum, namely, the coniferous-broadleaved mixed leaf extract > one single leaf extract > another single leaf extract. The rest of the coniferous-broadleaved mixed leaf extract treatment groups neutralized the allelopathic effects of S. indicum, namely, one single leaf extract > coniferous leaf mixed extract > another single leaf extract. The conclusions could provide a scientific basis for managing forests, especially mixed forest ecosystems. Full article

Parancistrocerus fulvipes (Saussure) (Hymenoptera: Vespidae), a predatory potter wasp, plays a crucial role in ecosystem services by preying on microlepidopteran larvae. This study investigated the effect of the temperature on the spring emergence and survivorship of P. fulvipes. We used seven different temperature regimes ranging from 5 to 38 °C to determine the developmental rate and thermal requirement for the emergence of P. fulvipes at each temperature. The development rates were determined using linear regression and a biophysical model (i.e., the Lactin model). Adult emergence occurred between 22 and 33 °C, and the lower developmental thresholds were 18.5, 17.1, and 17.8 °C for males, females, and both genders combined, respectively. The optimal temperature and upper-temperature threshold for spring emergence were 33 and 38 °C, respectively. The degree-day requirements for adult emergence were 201, 218, and 208 for males, females, and both genders combined. The lowest mortality was observed at 22 °C, while no P. fulvipes emerged at ≤13 °C and ≥38 °C. These findings provide a predictive model for the spring emergence of P. fulvipes, which can optimize ecosystem service programs in various agricultural systems, particularly in the context of climate change and pest management. Full article

Secondary metabolites (SM) in plants play crucial pharmacological, ecological, and nutritional roles for humans, wildlife, and livestock. Environmental Heterogeneity (EH) encompasses the variability of biotic and abiotic factors that influence biological responses of plant species. Advancements in remote sensing have enhanced the ability to assess plant functional traits more affordably and comprehensively by integrating spectral reflectance data with detailed plant metabolomics. However, studies investigating the relationship between EH—quantified using Rao’s Q heterogeneity index from remote sensing data—and SM diversity remain limited. Here, we present the first report demonstrating that the biotic component of EH, measured as Rao’s Q, is positively associated with SM diversity in mesquite pod extracts—higher Rao’s Q values correspond to greater SM diversity. Generalized additive models (GAMs) revealed that Rao’s Q contributed the most explanatory power, accounting for 21.2% of the deviance, compared to pod weight (13.7%) and pod length (2.03%). However, only the relationship between Rao’s Q and SM diversity was statistically significant (p = 0.029). The Rao’s Q index derived from remote sensing serves as a scalable proxy for identifying SM hotspots, facilitating the targeted discovery of regions with high pharmacological or nutritional value. Full article

Convolvulus persicus L. is an endangered narrow-range taxon, characteristic of the habitats along the coastal regions of the Caspian and the Black Seas. The aims of our research were to update the actual distribution area and the genetic evaluation of three representative populations from the western coastline of the Black Sea located in Sulina, Agigea, and Durankulak. ISSR amplifications were used to assess the genetic intrapopulation diversity and the genetic differentiation among populations. The average genetic polymorphism was 57.8 ± 16.03%. The intrapopulation genetic diversity parameters indicated that the Agigea population exhibits a higher genetic diversity, with this small population being part of the Agigea Marine Dunes Reserve. Although the interpopulation genetic distance was reduced (0.176–0.223) and the distribution of the total variation (AMOVA) was 57% within the population and 43% among the populations, the interpopulation genetic differentiation (PhiPT) was high (0.428, p < 0.001), probably due to the large geographical distances between the remaining populations. The populations’ genetic structures showed a lower genetic distance between the Agigea and Sulina samples. The clonability test supported the vegetative multiplication on the Durankulak and Sulina beaches. Our results showed that the genetic diversity and the distance among the populations in C. persicus were influenced by habitat conditions, destruction, and fragmentation, but also by conservation measures. Full article

The sustainability of reforestation initiatives depends on the involvement of local communities, whose lack of ownership compromises efforts to combat deforestation in the Lubumbashi Charcoal Production Basin. This study assesses reforestation activities in two village areas (Milando and Mwawa), based on individual interviews (50 individuals/village area) and floristic inventories carried out in two types of habitats (reforested and unexploited) for each village area. The hypotheses tested were the following: (i) Reforested habitats and tree species were selected collaboratively, ensuring an inclusive approach; (ii) ecological parameters—density per hectare, quadratic mean diameter, basal area, and floristic diversity—of reforested sites were comparable to those of unexploited miombo due to protection allowing natural recovery; and (iii) ethnobotanical and floristic patterns reflect varying levels of anthropogenic disturbance and the limited diversity of species used in reforestation. Thus, the interviews gathered data on habitat and woody species selection for reforestation and management practices, while the inventories assessed the condition of these reforested habitats in terms of density per hectare, basal area, quadratic mean diameter, and floristic diversity. The results show that in both village areas, the selection of habitats for reforestation was carried out concertedly (22.00–44.00% of citations). Woody species were chosen according to the needs of local communities (40–52%) and the availability of seeds (18.00–44.00%). Furthermore, management practices for these reforested habitats include planning/assessment meetings (26.00–38.00%) and maintenance activities, such as firebreaks (38.00–46.00%) and surveillance of reforested habitats (24.00%). Additionally, these practices are being increasingly neglected, jeopardizing reforestation efforts. However, density/ha, basal area, quadratic mean diameter, and floristic diversity did not show significant differences between reforested and unexploited habitats, particularly at Milando (p > 0.05). Furthermore, floristic similarity is 55.56% for reforested habitats and 93.75% for unexploited habitats but remains low between reforested and unexploited habitats (40.00–47.62%). This similarity between ethnobotanical and floristic lists is also low (43.75–31.58%). Finally, a total of 442 woody individuals were recorded in reforested habitats and 630 in unexploited ones, with Fabaceae dominating both habitat types. Despite some cited reforestation species like Acacia polyacantha being absent, Brachystegia spiciformis emerged as the most prevalent species in both reforested and unexploited areas. The results of the present study suggest a sustainable and continuous management of these reforested habitats for an effective reconstitution of the forest cover. To reinforce the sustainable management of these reforested habitats, it is recommended that decision-makers conduct awareness-raising campaigns and establish payment for environmental service mechanisms to motivate communities. Full article

The Central European fauna, in the last decades, has been undergoing a strong transformation due to four main factors: the retreat of living organisms that require cool and wet habitats, the proliferation of organisms that thrive in warm and dry conditions, the northward migration of Mediterranean organisms, and the gradual establishment of plants and animals with tropical origins. In this study, we detail the changes in the orders Diptera, Hymenoptera, and Lepidoptera and analyze the establishment of non native insects and the northward migration of Mediterranean insect species. The transformation towards a Mediterranean-type fauna is prominently indicated by the population in total abundance increase of xerothermic Aculeata, bee flies (Bombyliidae), and horse flies (Tabanidae). Additionally, groups that require cool and wet ecological conditions, particularly hoverflies (Syrphidae), but also sawflies (Tenthredinidae) and tachinid flies (Tachinidae), have shown a notable decline. In nocturnal moths, we observe a decrease in species richness in certain areas, as well as frequent outbreaks in populations of some less climate-sensitive species. Some species of butterflies are less sensitive to the current extent of climate change, exhibiting significant population in total abundance growth under protected conditions. However, most of the previously sporadic and rare butterfly species have proven to be climate-sensitive, unable to achieve significant population in abundance growth even under strict nature conservation. In recent decades, the influx from Mediterranean regions and the establishment of tropical non native insect species have turned at an exponential rate. We have reviewed the presence of alien insect species, recording 803 alien insect species in our region; 298 of them have arrived in the past quarter-century, with a significant proportion (54%) originating from tropical and Mediterranean regions. Full article

Benthic diatoms are being used as indicators to assess the biological quality of surface waters in Kosovo. The Klina River is the left tributary of the White Drin River Basin, with a length of 69 km. The study assessed the level of surface water quality in the Klina River using 12 diatomic indices calculated with the Omnidia program. For this purpose, three stations monitored the river Klina in the autumn of 2021 to conform to international standards. A total of 88 diatom taxa were identified, with the dominant species being Rhoicosphenia abbreviata (C. Agardh) Lange-Bertalot, Gyrosigma acuminatum (Kützing) Rabenhorst, Cocconeis placenula Ehrenberg, Gomphonema minutum (Ag.) Agardh f. minutum, Gomphonema clavatum Ehr, Meridion circulare (Greville) C.A. Agardh, Cocconeis pediculus Ehrenberg, Diatoma vulgaris Bory, and Nitzschia dissipata (Kützing) Grunow ssp. dissipata etc. This study assessed the surface water quality in the Klina River using diatom indices, indicating that the river is in good to moderate ecological condition. Environmental variables such as hydrogen ion concentration (pH) and dissolved oxygen (DO) had significant positive correlations (<0.01) with the biological diatom index (IBD), Descy’s pollution metric (Descy), Sladeček’s pollution metric (SLA), the European index (CEE), and Watanabe’s Index (WAT), while the total suspended solids (TSS) also showed a strong negative significant correlation (<0.01) with the generic diatom index (IDG), Indice Diatomique Artois Picardie (IDAP), the eutrophication pollution index (EPI-D), the trophic diatom index (TDI), the Pampean diatom index (IDP), and Steinberg and Schiefele’s index (SHE). Total phosphorus (TP), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) presented a significant negative correlation (<0.05) with the IBD, Descy, SLA, CEE, and WAT indices. Our findings provide insights for organizations dealing with the state of the environment and water protection in Kosovo, and these results can be used as a starting point for assessing the ecological quality of water and monitoring environmental pollution in the Kosovo region. Full article

Riparian zones, acting as transitional areas between aquatic and terrestrial ecosystems, boast a rich diversity of plant species. However, alterations in river hydrological regimes can significantly impact plant growth and distribution. In this study, seven typical reaches of Yongding River Basin were selected, and xylem water, soil water at different depths, and river water were collected in May and August. By measuring δ²H and δ¹⁸O values and combining with MixSIAR model, the proportion of water utilization by plants from different sources was quantified. The findings revealed that δ²H and δ¹⁸O values of river water, soil water, and plant xylem water were higher in August compared to May. While there was no significant difference in δ²H and δ¹⁸O values between river and soil water during different periods (p > 0.05), significant differences were observed in δ¹⁸O in plant xylem water (p = 0.022). Regardless of whether it was May or August, herbaceous plants utilized river water more extensively than trees and shrubs, and hydrophytes exhibited a higher dependence on river water compared to mesophytes and xerophytes. Some hygrophytes (P. anserina, etc.) utilized river water for over 90% of their total water intake. There were significant differences between herbs and trees and shrubs in the proportion of river water usage in August (p = 0.001). Moreover, considerable variations existed in the proportion of river water usage among different water ecotypes in both May (p = 0.005) and August (p < 0.001). Our findings provide a scientific basis for the rational allocation of plants in the process of riparian vegetation restoration. Full article

Between 1995 and 2022, 19 measuring points in small and medium sized streams in the Harz National Park, Germany, were sampled. The samples were evaluated in terms of their macroinvertebrate (MI) biology and hydrochemistry. Nearly all streams showed a natural hydromorphology, and low values of biological oxygen demand (BOD) characteristic for rivers not contaminated by organic matter. Nevertheless, in the 1990s, most streams were still only settled by a small number of MI species. However, by 2022, the MI species number had doubled or tripled in most cases, with a maximum increase from 14 to 52. There is a clear correlation between species number and pH. At 15 of the 19 sampling sites, the acidity class has gotten better by at least one value. Thus, acid-sensitive species, mainly from the taxonomic orders Trichoptera, Plecoptera, and Ephemeroptera, have been able to settle higher altitudes, as well as formerly acidic reaches. In general, the streams contain a very specific macroinvertebrate fauna that emphasizes the conservation value of the Harz National Park. Attenuation of acidification has not only influenced the MI diversity. Along with the increase in pH, fish populations have recovered, and formerly fish-free stream sections have been recolonised. The biological recovery of the streams has also been fostered by the breakdown of spruce forest monocultures in the surroundings, the natural development of deciduous trees on the banks, and increasing levels of DOC (dissolved organic carbon). Full article