Stable Ecological Conditions Research Articles

Spatial–Temporal Evolution Characteristics and Driving Mechanism Analysis of the “Three-Zone Space” in China’s Ili River Basin

The Ili River Basin (IRB) is located in the northwest of China. With its large-scale zone and abundant resources, it is believed to be a “wet island” and a biotic resource storehouse in the dry regions of Eurasia. The IRB has stable ecological conditions and abundant water resources, providing natural conditions for agricultural production and human settlements. With the population increasing and economic development advancing, the competition for land resources is becoming fierce, leading to some ecological problems in this region. Therefore, understanding the spatiotemporal changes and driving mechanisms of the “three-zone space” (TZS) in the IRB is of significant practical importance for promoting sustainable development and optimizing the territorial spatial pattern. This study first analyzes the characteristics and intensity of the TZS changes from 2000 to 2020. Then, it utilizes the optimized parameter Geodetector (OPGD) to analyze the driving mechanisms behind these changes. The results show the following. Firstly, the agricultural space (AS) increased by a total of 837.5 km2, the urban space (US) increased by 519.64 km2, and other ecological space (OES) increased by 1518.83 km2. Green ecological space (GES) decreased by 2875.97 km2. Secondly, intensity analysis indicated that the total TZS change in IRB was 11.07%. At the spatial-type level, the increased intensities of OES, US, and AS were active. In spatial transformation intensity, US and OES tended to transform into AS; AS tended to transform into US; and OES and GES had a mutual transformation tendency. Thirdly, AS converted into US around emerging cities like Khorgas and Cocodala. The conversion towards GES was scattered. The mutual conversion between OES and GES showed spatial distribution consistency, mainly occurring in the Borohoro ranges and the Halik ranges. Lastly, regarding the driving mechanisms, the evolution of US in the IRB was driven by social and economic factors. Location and climate factors accelerated agricultural development, facilitating the transformation of GES and OES into AS. Climate and economic factors played a crucial role in the scale of conversions between OES and GES. The findings can provide a basis for the governance and protection of the IRB, help to form a rational territorial spatial pattern, and offer scientific guidance for sustainable land management.

The Palaeo-Productivity Signals Chronicled from the Buxa Formation, North-East Lesser Himalaya, India

ABSTRACT The Mesoproterozoic era is known for its relatively stable ecological conditions and limited atmospheric oxygen. Despite this understanding, uncertainties remain about how ocean chemistry evolved during this time and its potential impact on the development of complex eukaryotic life forms. In response to these uncertainties; we have undertaken a study to investigate indicators of ancient productivity within the Buxa Formation of the Lesser Himalaya in Sikkim. By analyzing the isotopic values ( δ13 C and δ 18Ο values) as well as Rare Earth Element (REE) composition, a total n = 151 carbonate samples were investigated across three sections of the Buxa Formation: Jorethang to Mangalbare, Legship to Naya Bazar, and Reshi to Mangalbare, Sikkim. The study’s findings show that there was minimal variation in δ13C values, consistently ranging between –0.5 and +2.5 ‰ VPDB. This pattern suggests a relatively steady and moderately high level of productivity during that time. This productivity might have been influenced by a temporary increase in atmospheric oxygen levels. Additionally, we have also reviewed and examined stromatolites as part of the investigation.

Latest Pleistocene-Holocene sedimentary evolution from sediment records of the Tam Giang-Cau Hai coastal lagoon system, central Vietnam

The latest Pleistocene-Holocene sedimentary evolution was reconstructed from two boreholes collected in the Tam Giang-Cau Hai coastal lagoon region of central Vietnam. This research was based on analyzing radiocarbon dating, grain size, sedimentary structure, petrological components, and diatom assemblages. Besides, some high-resolution seismic data from the lagoon water body were interpreted to estimate Holocene sediment thickness. Sedimentary records of two boreholes revealed various sedimentary facies under the sea-level change since the Last Glacial Maximum (LGM): Fluvial channel facies, fluvial-lagoonal transition facies, lagoon facies, lagoonal-to-fluvial facies, and flood plain facies. Radiocarbon dating indicated that the coastal lagoon system possibly initiated around 8.8–8.5 cal kyr BP, corresponding to the meltwater pulse 1 C when saltwater intruded into the lagoon system. The borehole-sediment data combined with the high-resolution seismic data shows the thickness of Holocene sediments is approximately 20–35 m in the lagoon region. The study also suggested that the sandy barrier complex along the coast between the lagoon system and the open sea has been likely built during the transgression since 10–8.8 cal kyr BP. Additionally, five ecological zones were identified based on diatom assemblages in borehole HK02 indicating variations in marine and fluvial influence in the coastal lagoon system during the past 8.8 kyr: Dia-HK02–1 indicates a low presence of diatoms, suggesting a weak marine influence in the coastal lagoon system; Dia-HK02–02 shows the strongest marine influence and stable ecological conditions in the coastal lagoon system; Dia-HK02–03 demonstrates a partial decrease in marine influence; Dia-HK02–4 shows an increasing fluvial influence; and Dia-HK02–5 developed under completely dominated fluvial conditions on land.

Assessment of Ecological Quality and Analysis of Influencing Factors in Coal-Bearing Hilly Areas of Northern China: An Exploration of Human Mining and Natural Topography

The Changhe Basin is located in the earth–rock mountainous area in southeastern Shanxi, China, and represents a characteristic northern coal-bearing hilly area. The terrain is complex, and the area is rich in coal mines. It plays an indispensable role in maintaining ecological balance and sustainable development in North China. To investigate the changes in ecological quality in the Changhe Basin, as well as the impact of human mining activities and natural topography on ecological quality, this study constructs the Remote Sensing Ecological Index (RSEI) based on Landsat remote sensing images from 2001, 2008, 2015, and 2022, undertaking an analysis of the spatial–temporal distribution characteristics of the ecological quality and its changing trends over the past 20 years. Additionally, spatial autocorrelation distribution features are revealed using Moran’s I. The exploration extends to examining the relationship between mining activities and the surrounding ecological quality. Subsequently, we study the relationship between Topographic Wetness Index (TWI) and RSEI. The results indicate the following: (1) On the temporal scale, the average proportion of RSEIs categorized as excellent and good from 2001 to 2022 is 46.78%. Types showcasing stable ecological conditions average 52.49%. The level of overall ecological quality of the basin has remained consistently high. On the spatial scale, the western part of the Changhe River, particularly in mountainous areas, exhibits higher ecological quality. Poorer areas concentrate in Chuandi Town in the southwestern part, and are significantly impacted by mining activities. The eastern region manifests areas undergoing either rapid or gradual degradation. (2) The four-phase Moran index results reveal a robust positive correlation in the spatial distribution of ecological quality within the basin. High–High and Low–Low clusters dominate, while High–Low and Low–High distributions are scattered. (3) Mining activities exert a discernible impact on the surrounding ecological quality. As the distance from the buffer zone outside the mining area increases, RSEI gradually decreases. The impact level exhibits an initial increase and subsequent decrease from 2001 to 2022.

Differences in the vegetation dynamic patterns of three tropical secondary forests in South Sulawesi, Indonesia

Abstract. Putra PS, Yamada T, Achmad A, Nasri N, Hamzah AS, Ngakan PO. 2023. Differences in the vegetation dynamic patterns of three tropical secondary forests in South Sulawesi, Indonesia. Biodiversitas 24: 5065-5073. Degraded forests experience dynamics that drive them towards stable ecological conditions as a result of the succession process. Understanding the dynamics of forests through succession is a requirement for secondary forest management activities. The purpose of this research was to uncover the dynamics of population, species composition, and dominance in three secondary tropical forest communities: (i) Karst forest, (ii) Lowland forest, and (iii) Pinus merkusii plantation forest. Permanent plots with areas tailored to the richness of each forest community were constructed, and vegetation studies were conducted annually from 2019 to 2022. The results revealed that the ten most dominant species in each plot shared only one species. The rest were exclusive to a single community. During the four years of research, 25 out of a total of 90 species (Karst), 27 out of a total of 68 species (Lowland), and 12 out of a total of 43 species (Pine) experienced dynamics in the form of an increase or decrease in population. Tree density decreased in the Karst plot and fluctuated slightly in the Lowland and Pine forest plots. Meanwhile, the basal area cover continued to increase during the 4 years of observation. Comparing age and pre-succession land use history, soil type and restoration history appear dominant in determining the forest dynamics.

Functional morphology of prey capture in stream-dwelling sailfin silversides (Telmatherinidae) based on high-speed video recordings

Understanding how ecology shapes the evolution of morphological traits is a major goal in organismal biology. By quantifying force of motion, hypotheses on the function of fundamental tasks of animals like feeding can be tested. Ray-finned fishes use various feeding strategies, classified into three main feeding modes: suction, ram and manipulation. While manipulation feeders are usually distinct in morphology and feeding behavior, differentiation between suction and ram feeders is often fine-scaled and transitional. Previous studies have identified different feeding modes and biomechanical adaptations on interspecific and intersexual levels in lake-dwelling sailfin silversides, species of a Sulawesi freshwater radiation. Functional feeding morphology of stream-dwelling species remained in contrast unstudied. We hypothesized that different requirements of riverine habitats favor the evolution of alternative functional adaptations in stream-dwelling sailfin silversides. To test this hypothesis, we investigated feeding of two phenotypically distinct riverine species, Telmatherina bonti and Marosatherina ladigesi, and their sexes, by high-speed videos and biomechanical models. The kinematic approaches identify T. bonti as ram feeder and M. ladigesi as suction feeder. Surprisingly, the biomechanical models of the jaw apparatus provide contradicting results: only one out of three studied parameters varies between both species. Contrarily to lake-dwelling Telmatherina, sexes of both species do not differ in feeding biomechanics. We conclude that T. bonti predominantly uses ram feeding while M. ladigesi primarily uses suction feeding as its main hunting strategy. Feeding biomechanics of stream-dwelling sailfin silversides are less distinct compared to lake-dwelling species, likely due to different trophic ecologies or less stable ecological conditions.

Population dynamics linked to glacial cycles in Cercis chuniana F. P. Metcalf (Fabaceae) endemic to the montane regions of subtropical China.

The mountains of subtropical China are an excellent system for investigating the processes driving the geographical distribution of biodiversity and radiation of plant populations in response to Pleistocene climate fluctuations. How the major mountain ranges in subtropical China have affected the evolution of plant species in the subtropical evergreen broadleaved forest is an issue with long‐term concern. Here, we focused on Cercis chuniana, a woody species endemic to the southern mountain ranges in subtropical China, to elucidate its population dynamics. We used genotyping by sequencing (GBS) to investigate the spatial pattern of genetic variation among 11 populations. Geographical isolation was detected between the populations located in adjacent mountain ranges, thought to function as geographical barriers due to their complex physiography. Bayesian time estimation revealed that population divergence occurred in the middle Pleistocene, when populations in the Nanling Mts. separated from those to the east. The orientation and physiography of the mountain ranges of subtropical China appear to have contributed to the geographical pattern of genetic variation between the eastern and western populations of C. chuniana. Complex physiography plus long‐term stable ecological conditions across glacial cycles facilitated the demographic expansion in the Nanling Mts., from which contemporary migration began. The Nanling Mts. are thus considered as a suitable area for preserving population diversity and large population sizes of C. chuniana compared with other regions. As inferred by ecological niche modeling and coalescent simulations, secondary contact occurred during the warm Lushan–Tali Interglacial period, with intensified East Asia summer monsoon and continuous habitat available for occupation. Our data support the strong influence of both climatic history and topographic characteristics on the high regional phytodiversity of the subtropical evergreen broadleaved forest in subtropical China.

The importance of tropical mountain forests for the conservation of dragonfly biodiversity: A case from the Colombian Western Andes

Forests have been widely recognized as key habitats for odonate (dragonflies and damselflies) biodiversity, but the importance of forests for holding odonate biodiversity remains understudied in tropical mountains, one of the most diverse ecosystems on the planet. Here we described the odonate assemblage composition along the elevation gradient in the Tatamá Mountains (Colombian Cordillera Occidental). We analyzed the effects of elevation, habitat, and suborder on species richness and endemism. We found that the richest assemblage occurred in the foothills between 300 and 600 m, where the biotas of the Chocó biogeographic region and the Tropical Andes converge. Anisoptera richness was higher in open-habitat habitats, that of Zygoptera higher in forests. Richness and endemism decreased with elevation, and no relation between habitat and richness was found. However, the number of endemic species was strongly related to forests, which harbored 25 out of 28 endemic species. Also, forest odonates had narrower elevation ranges than open-habitat odonates. These patterns can be explained because tropical mountains were historically covered by forests, while open habitats derived from human activities (i.e., pastures) have flourished in the past centuries. The forest odonate assemblages at different elevations have been evolving for millions of years, in relatively stable ecological conditions, which could promote the high number of forest endemics in the tropical mountains. Our results emphasize the role of tropical mountain forests in the conservation of Odonata diversity.

DYNAMIC STATE OF ECOSYSTEM CARRYING CAPACITY UNDER ISLAND URBANIZATION: A CASE STUDY OF PINGTAN ISLAND IN THE SOUTHEASTERN COAST OF CHINA

The assessment of ecological environment during the large-scale development of islands is a major topic in the study of current coastal islands. Choosing the appropriate assessment method to evaluate the suitability of carrying capacity of islands and making relevant suggestions are significant to the sustainable development of islands. Ecological footprint method is used to analyze the ecological carrying capacity of Pingtan Island (PI) from 2005 to 2016 for promoting the coordinated rational development and construction and ecological environment of the island. Although PI is in rapid urban development and construction, the island maintains secure and stable ecological conditions. PI is used as a research case to analyze the sustainable development of the ecological environment through the carrying capacity of the island ecosystem.

The contrasting evolution of twin volcanic lakes (Monticchio, Mt. Vulture, Italy) inferred from literature records

Lago Piccolo and Lago Grande di Monticchio lie in the collapsed caldera of the volcanic structure of Mt. Vulture (Basilicata, Italy). In over two centuries, a number of studies on their water and on their submerged and riparian vegetation, were carried out, demonstrating an interesting biodiversity. The entire lake area, which is impacted by strong tourist pressure, is part of the "Monte Vulture" Special Area of Conservation (SAC IT9210210). The aim of this paper is to review the literature studies on these lakes, in order to identify the more suitable limnological parameters to infer the history of the trophic status of the two lakes. For this reason, we assess the current ecological status of the two lakes on the basis of physical, chemical and biological analyses deriving from two recent surveys carried out in 2005-2007 and in 2015, and compare these data with sparse, but relevant, historical records, in order to assess how human impacts affected both these lakes and to understand the differences in their present trophic status. Because of its peculiar water chemistry, Lago Piccolo is resulted in good and stable ecological conditions. On the contrary, water transparency of Lago Grande came out very low in summer, while total phosphorus and nitrogen concentration are proved high, leading to the persistence of critical environmental conditions in this lake, with high algal biomass and durable algal blooms in late summer, dominated by cyanobacteria. Finally, in absence of standard protocols and seasonal samplings, the macrophyte maximum growing depth should be considered the more reliable indicator of trophic status among those available for these specific lakes, being relatively independent from sampling methods and seasonal pattern.

Improving Ecological Restoration to Curb Biotic Invasion—A Practical Guide

AbstractCommon practices for invasive species control and management include physical, chemical, and biological approaches. The first two approaches have clear limitations and may lead to unintended (negative) consequences, unless carefully planned and implemented. For example, physical removal rarely completely eradicates the targeted invasive species and can cause disturbances that facilitate new invasions by nonnative species from nearby habitats. Chemical treatments can harm native, and especially rare, species through unanticipated side effects. Biological methods may be classified as biocontrol and the ecological approach. Similar to physical and chemical methods, biocontrol also has limitations and sometimes leads to unintended consequences. Therefore, a relatively safer and more practical choice may be the ecological approach, which has two major components: (1) restoration of native species and (2) biomass manipulation of the restored community, such as selective grazing or prescribed burning (to achieve and maintain viable population sizes). Restoration requires well-planned and implemented planting designs that consider alpha-, beta-, and gamma-diversity and the abundance of native and invasive component species at local, landscape, and regional levels. Given the extensive destruction or degradation of natural habitats around the world, restoration could be most effective for enhancing ecosystem resilience and resistance to biotic invasions. At the same time, ecosystems in human-dominated landscapes, especially those newly restored, require close monitoring and careful intervention (e.g., through biomass manipulation), especially when successional trajectories are not moving as intended. Biomass management frequently uses prescribed burning, grazing, harvesting, and thinning to maintain overall ecosystem health and sustainability. Thus, the resulting optimal, balanced, and relatively stable ecological conditions could more effectively limit the spread and establishment of invasive species. Here we review the literature (especially within the last decade) on ecological approaches that involve biodiversity, biomass, and productivity, three key community/ecosystem variables that reciprocally influence one another. We focus on the common and most feasible ecological practices that can aid in resisting new invasions and/or suppressing the dominance of existing invasive species. We contend that, because of the strong influences from neighboring areas (i.e., as exotic species pools), local restoration and management efforts in the future need to consider the regional context and projected climate changes.

Parental hormones are associated with crop loss and family sickness following catastrophic flooding in lowland Bolivia

The physiology of fatherhood is a growing field of study, and variability in hormonal mediators of reproductive effort (e.g. testosterone, cortisol) can predict variability in paternal investment. Studies often find that lower testosterone levels are associated with increased paternal investment, though most studies are conducted under relatively stable ecological conditions. In this paper, we examine parental physiological correlates of crop loss and family health problems among Tsimane forager-horticulturalists following a catastrophic flood in lowland Bolivia. Immediately after a devastating 2014 flood that impacted >75% of Tsimane communities, we conducted structured interviews examining crop losses and morbidity, and collected saliva specimens from 421 parents (n = 292 households) to analyze cortisol and testosterone. Over 98% of interviewees reported horticultural losses, with the average family losing 88% of their crops, while 80% of families reported flood-induced injuries or illnesses. Controlling for age, body mass index, and time of specimen collection, men's testosterone was negatively associated with both absolute cropland losses (Std. β = −0.16, p = 0.037), and percent of cropland lost (Std. β = −0.16, p = 0.040). Female testosterone was not associated with crop losses. Using the same control variables, both male and female cortisol was negatively associated with a composite measure of child health burden (fathers: Std. β = −0.34, p < 0.001; mothers: Std. β = −0.23, p = 0.037). These results are discussed in the cultural context of a strong sexual division of labor among Tsimane; we highlight the physiological and psychosocial costs of experiencing a natural disaster, especially for paternal caregivers in a nutritionally and pathogenically stressed subsistence population where cultigens provide the majority of calories in the diet.

Genetic structure of the Turkish hamster (Mesocricetus brandti)

We examined the natural population structure of the Turkish hamster (Mesocricetus brandti) by analysing partial mitochondrial sequences of the control region and the cytochrome b gene. Evolutionary lineages were defined on haplotype clusters in genetic trees and a median-joining network. Most significant divergence events in M. brandti nested in the lower Pleistocene. Gene flow prevented spatial genetic differentiation among most populations contrasting previous ideas about potential subspeciation in Anatolia. None of the mitochondrial lineages showed significant signs of recent expansion indicating relatively stable ecological conditions during recent population history. Furthermore, we discussed aspects of the evolution of M. brandti and the genus Mesocricetus in the context of available fossils.

Inter-annual variation in clutch size and laying date of Rufous Bush Chats Cercotrichas galactotes inhabiting an Algerian oasis

We studied clutch size and timing of breeding of Rufous Bush Chats Cercotrichas galactotes inhabiting Date Palm plantations in an oasis in NE Algeria with respect to interannual variation. Although oases may be assumed to provide relatively stable ecological conditions favourable for some insectivorous birds, including Rufous Bush Chats, we found relatively high year-to-year variation in the life history traits analysed. In general, clutch size was negatively related to the egg-laying date, with this relation differing between years. This suggests that clutch size was probably determined by a combination of within-year and between-year factors partly operating through the timing of reproduction. The most important of these factors were probably the amount of rainfall and year-to-year growth of palm trees.

Pleistocene to Holocene benthic foraminiferal assemblages from the Peruvian continental margin

The benthic foraminiferal inventory and their assemblage composition was documented along five sediment cores from the Peruvian margin between 3°S and 18°S at water depths of 500 to 1250 m, covering the lower boundary of today’s Oxygen Minimum Zone (OMZ). Emphasis was given to certain time intervals during the last 22 thousand years when different climatic and oceanographic conditions prevailed than today. In total three agglutinated and 186 calcareous species were recognised. Bolivina costata, Bolivinita minuta, Cassidulina delicata and Epistominella exigua were most abundant. The foraminiferal distributions revealed a marked change in assemblage composition particularly at the deeper cores during and after the deglaciation. The diversity declined and Bolivina species became dominant. These changes took place gradually over several millennia, and high-frequency fluctuations were not recorded. This pattern provides evidence for rather stable ecological conditions and sluggish changes in bottom water circulation during the last deglaciation.

Changes in macrozoobenthic assemblages in a shallow subtropical lake (Lake Taihu, China): 1987–1988 vs. 2007

Lake Taihu is subject to severe eutrophication due to high nutrient inputs. We compared the macrozoobenthic assemblages of Lake Taihu in 1987–1988 and in 2007. Changes in benthic communities between the two periods were significantly different among the four lake regions (the River Mouth, the North Bay, the Open Lake, and the East Bay), corresponding well with the changed environmental conditions. The River Mouth and North Bay showed the greatest changes in benthic fauna, corresponding with severe degradation in water quality. In 1987–1988, benthic communities were dominated by Tubificidae and Bivalvia in the River Mouth and the North Bay, respectively. In 2007, however, benthic fauna were mainly dominated by Tubificidae in the North Bay and total macrozoobenthos increased approximately 18-fold in abundance. The Open Lake was dominated by bivalves (mainly Corbicula fluminea) in both sampling periods, whereas an increased abundance of bivalve was observed from 1987–1988 to 2007. In the East Bay, which was covered by abundant macrophytes, the macrozoobenthos community decreased in abundance and was characterized by high species richness of gastropods. In addition, the abundance of gastropods, tubificids, and chironomids increased significantly between the two sampling periods. The relatively stable ecological conditions in the East Bay (e.g., trophic state and spatial distribution of macrophytes within the East Bay) might be responsible for the relatively small changes. Our results showed complex variation patterns of macrozoobenthic assemblages among different sections of Lake Taihu, which may be associated with the great environmental heterogeneity in this large shallow lake.

Territorial Systems, Regional Disparities and Sustainability: Economic Structure and Soil Degradation in Italy

The present study was devoted to identify the evolutionary path of a number of local systems in a Mediterranean country vulnerable to soil degradation (SD) in the last decades. A multivariate analysis was used to evaluate the socio-ecological conditions and to estimate rapidity-of-change of local systems by considering 6 bio-physical factors predisposing soil to degradation and 23 socioeconomic indicators over fifty years (1960–2010). Results indicate that systems’ development paths diverged during the investigated time period reflecting changes in the spatial organization and in the economic base of entire regions. Interestingly, economic performance and environmental quality do not seem to follow opposite trajectories. Local systems characterized by low per-capita income, agricultural specialization and population ageing, seem not to be associated with better and more stable ecological conditions. Local systems in affluent areas, featuring a mix of socioeconomic conditions with the prevalence of services in the economy and tourism specialization, showed relatively good ecological conditions and moderate-to-low SD vulnerability. Thus, affluent local systems do not necessarily reflect a higher pressure on the environment. These findings suggest that areas with a changing socio-demographic profile and a dynamic economic structure are compatible with low and stable levels of SD vulnerability.

Paleolimnological assessment of ecological integrity and eutrophication history for Lake Tiiläänjärvi (Askola, Finland)

In this study, we aim to reconstruct long-term limnoecological development of the clay-turbid Lake Tiilaanjarvi in Askola, southern Finland, using fossil Chironomidae assemblages. The study lake suffers from hypereutrophic conditions and late-winter and end-of-summer anoxia. The retrieved sediment record revealed a succession from oligo-mesotrophic (~AD 1940–2000) to eutrophic community (~AD 2000–2010) that finally reached hypereutrophic climax community in the most recent sediments. The initial state of the record was characterized by stable ecological conditions, but the biological integrity (community and functional diversity) was completely lost in the upper part of the sediment profile. The number of taxa markedly decreased following the nutrient enrichment and only one taxon (Chironomus plumosus-type), tolerant of temporary anoxia, remained in the surface sample. During the period of available observational data (since AD 1978), variance in midge community composition was mostly explained by limnological factors, namely total phosphorus (TP), whereas the influence of climate was statistically insignificant, thus enabling quantitative midge-based reconstruction of autumnal epilimnetic TP. The midge-based reconstruction showed an identical trend compared to sediment characteristics, which correspond to increased lake productivity and anthropogenic activities in the catchment. The inferred values for the initial state indicated mesotrophic conditions, which are typical for non-disturbed clay-turbid lakes in southern Finland, and a subsequent increase to eutrophic conditions, with hypereutrophic state reached at the top of the core. This development corresponds with the instrumentally monitored development. In addition, when the reconstruction was compared with the instrumental values, the inferences were mostly (75 % of the samples) within the error estimates of the model. The present results provide invaluable information on the limnoecological development of Lake Tiilaanjarvi, and more generally, support the theory that fossil remains of chironomids provide a useful tool for assessments of eutrophication history and biological integrity.

Role of environmental factors in the spread of domestic trout in Mediterranean streams

Summary Overharvesting, habitat alteration and pollution have contributed to the decline of many wild populations of brown trout in Europe. Since the mid‐19th century, stocking with domestic strains has added a further threat to their genetic integrity. In this study, we adopted a landscape genetic approach to evaluate the role of environmental factors in promoting or hindering invasion by an alien genome. Two classes of molecular markers (LDH‐C1* locus and mtDNA) were used to evaluate the level of introgression between native and domestic strains of brown trout in Central Italy. A multivariate method (redundancy analysis, RDA) was employed to find relationships between genetic diversity and 19 environmental variables that describe lithology, geomorphology, fish community and human activities. The RDA indicated that streams with more stable ecological conditions sustain almost pure native populations, whereas streams characterised by unpredictable hydrological conditions harbour populations with high levels of introgression or pure for foreign genotypes. Our study revealed that the outcome of supplementary stocking with hatchery‐reared brown trout is strongly linked to the environmental features of different drainage basins.

Response to oxygen deficiency (depletion): Bivalve assemblages as an indicator of ecosystem instability in the northern Adriatic Sea

Benthic communities represent a powerful tool for the detection of natural and anthropogenic disturbances, as well as for the assessment of marine ecosystem stability. This paper shows that bivalve assemblages could serve as excellent indicators of disturbance and ecosystem instability. The goal of this study was to compare two sets of data in order to determine the differences between two different periods belonging to bivalve assemblage in the muddy detritic bottom of the northern Adriatic Sea in the post-anoxic period during December 1989, 1990, 1991 and quite a while later, during 2003, 2004 and 2005. Abundances of some indicator species such as Corbula gibba, Modiolarca subpicta and Timoclea ovata were detected during the post-anoxic period. Recruitment in the quality of bivalve assemblages was proved by the ecologic and biotic indexes during 2003, 2004 and 2005, during a period of relatively stable ecological conditions. Fluctuation in bivalve diversity due to the ecological quality of the marine ecosystem in the eastern part of the northern Adriatic Sea is also discussed.