Main Water Body Research Articles

Electrical Potential of Leaping Eels

When approached by a large, partially submerged conductor, electric eels (Electrophorus electricus) will often defend themselves by leaping from the water to directly shock the threat. Presumably, the conductor is interpreted as an approaching terrestrial or semiaquatic animal. In the course of this defensive behavior, eels first make direct contact with their lower jaw and then rapidly emerge from the water, ascending the conductor while discharging high-voltage volleys. In this study, the equivalent circuit that develops during this behavior was proposed and investigated. First, the electromotive force and internal resistance of four electric eels were determined. These values were then used to estimate the resistance of the water volume between the eel and the conductor by making direct measurements of current with the eel and water in the circuit. The resistance of the return path from the eel's lower jaw to the main body of water was then determined, based on voltage recordings, for each electric eel at the height of the defensive leap. Finally, the addition of a hypothetical target for the leaping defense was considered as part of the circuit. The results suggest the defensive behavior efficiently directs electrical current through the threat, producing an aversive and deterring experience by activating afferents in potential predators.

Seletividade da pesca da viola Loricariichthys anus (Siluriformes: Loricariidae) na Lagoa Mirim, RS, Brasil

A Lagoa Mirim é um dos principais corpos hí­­dricos do sistema lagunar meridional da América do Sul e possui regime de águas compartilhadas entre o Brasil e o Uruguai. A atividade pesqueira na região apresenta diminuição dos ní­­veis de captura, fazendo com que os pescadores aumentem o esforço de pesca. A viola (Loricariichthys anus) é uma das espécies nativas mais importante da região para a pesca artesanal, sendo assim, faz-se necessário o estudo de seus estoques e do esforço pesqueiro adequado. O objetivo do trabalho foi identificar o tamanho de malha que apresenta maior eficiência do ponto de vista econômico e sustentável para a pesca da viola. O estudo foi desenvolvido utilizando-se 10 redes de malha de 60 mm, 10 redes de malha 70 mm e 10 redes de malha 80 mm entre nós opostos. A pesca foi realizada com o conjunto das diferentes malhas, dispostas intercaladas, por um perí­­odo de 12 horas í­Â noite, de acordo com o procedimento dos pescadores locais. O número total de peixes capturados em cada malha foi distribuí­­do por classe de comprimento total e determinada a seletividade. O resultado indica que a malha 70 mm é mais eficiente, capturando peixes com tamanho mí­­nimo superior ao da primeira desova, o que a torna, portanto, a mais recomendada para a pesca da viola na Lagoa Mirim, RS.

Characteristics of tidal action sedimentary system and distribution of favorable sand bodies of Silurian in Tazhong area, Tarim basin, NW China

The 3rd upper sub-member of the Silurian Kepingtage formation has developed marine clastic sediments and is an important petroleum exploration and development set in Tazhong area, Tarim basin, NW China, of which the sedimentary system and favorable reservoir distribution have been researched in detail based on the drilling, logging, seismic, experimental data and the theory of sequence stratigraphy. The results show that it was overlap and edge away layer by layer from northwest to southeast. On the background of marine transgression, the depositional systems of tidal flat, estuary and tidal reformation delta were developed and controlled by palaeogeomorphology, while different types of sand bodies and sedimentary formations were developed owing to the difference of types and energies of main action water bodies. In the sedimentary system of tidal flat, the main types of sand bodies are subtidal tidal channels which show significantly banded distribution vertical to the coast with a complete three-tier structure. The sand bodies of tidal bars are common in the estuary sedimentary system and extend far parallel to the axis of the estuary with thin layers of mudstone. The sand bodies of underwater distributary channels are developed with upward-finning positive rhythm and large erosion surfaces in the tidal delta sedimentary system and distributed like a bird-foot shape. By above research, the depositional mode of tidal flat-estuary-delta in Tazhong area has been established and the distribution of favorable reservoirs has been predicted.

LARGE SCALE VERTICAL ELECTRICAL SOUNDINGS SURVEY IN ANTHEMOUNTAS RIVER BASIN FOR EVALUATING HYDRAULIC COMMUNICATION BETWEEN SUB BASIN AQUIFERS

In Anthemountas river basin a number of studies have taken place mainly because of the significant drop of underground water level observed in the beginning of the last decade. Data from existing hydrowells show the existence of a complex aquifer with the two main underground water bodies situated east and west of the region of Vasilika and Galarinos villages respectively. A large scale geophysical survey took place consisting of Vertical Electrical Soundings (VES) and Electrical Resistivity Tomography (ERT). The main area of interest is in the central region of the basin between Vasilika and Galarinos villages where eighty five (85) VES (Schlumberger array), located on a regular grid revealed a three dimensional model for the sedimentary formations while mapping the bedrock down to a depth of more than 600m has been achieved. In the same area, ERT measurements and geological information derived from borehole data are used to obtain a more detailed geological model for the area of interest. From surface to bedrock depth, the hydraulic communication between these two water bodies is examined. Furthermore significant geological features are observed and discussed.

Latvijas zemieņu un augstieņu upju īpašību pētīšana ar Latvijas hidroģeoloģiskā modeļa palīdzību

The Water Framework Directive of European Union recommends applying the river drainage basin principle for defining the boundaries of groundwater bodies. This principle has been used in Latvia for establishing boundaries for the main water bodies of the country. By using the hydrogeological model of Latvia (LAMO), scientists of Riga Technical University tested the applicability of the principle for lowland (Iecava) and hilly (Malta) river drainage basins. The groundwater mass balances of basins were examined and the MODPATH particle tracking was applied. It was discovered that only for the Quaternary system, the principle can be used, because there the groundwater flow through the basin border was relatively small. The principle does not hold for the primary strata. In Latvia, drinking water is mostly provided by the primary strata. For this reason, the boundaries of the main groundwater bodies should be revised. The research was supported by the Latvian State Research Program EVIDEnT.

Enhanced greenhouse gas emission from exposed sediments along a hydroelectric reservoir during an extreme drought event

An active debate has been underway on the magnitude and duration of carbon (C) emissions from hydroelectric reservoirs, yet little attention has been paid to stochastic C emissions from reservoir sediments during extreme climatic events. A rare opportunity for field measurements of CO2 efflux from a hydroelectric reservoir in Korea during an extreme drought event was used to examine how prolonged droughts can affect microbial organic matter processing and the release of CO2, CH4 and N2O from exposed sediments. Chamber measurements of CO2 efflux along an exposed sediment transect, combined with high-frequency continuous sensor measurements of the partial pressure of CO2 (pCO2) in the reservoir surface water, exhibited extraordinary pulses of CO2 from exposed sediments and the turbulent inflowing water in contrast to a small CO2 sink in the main water body of the reservoir and a low efflux of CO2 from the flooded sediment. Significant increases in the production of CO2, CH4 and N2O observed in a laboratory incubation of sediments, together with enhanced activities of phenol oxidase and three hydrolases, indicate a temporary activation of microbial organic matter processing in the drying sediment. The results suggest that drought-triggered pulses of greenhouse gas emission from exposed sediments can offset the C accumulation in reservoir sediments over time scales of years to decades, reversing the trend of declining C emissions from aging reservoirs.

Water mass circulation and weathering inputs in the Labrador Sea based on coupled Hf–Nd isotope compositions and rare earth element distributions

The Labrador Sea is one of the key areas for deep water formation driving the Atlantic thermohaline circulation and thus plays an important role in Northern Hemisphere climatic fluctuations. In order to better constrain the overturning processes and the origins of the distinct water masses, combined dissolved Hf–Nd isotopic compositions and rare earth element (REE) distribution patterns were obtained from four water depth profiles along a section across the Labrador Sea. These were complemented by one surface sample off the southern tip of Greenland, three shallow water samples off the coast of Newfoundland, and two deep water samples off Nova Scotia.Although light REEs are markedly enriched in the surface waters off the coast of Newfoundland compared to north Atlantic waters, the REE concentration profiles are essentially invariant throughout the water column across the Labrador Sea. The hafnium concentrations of surface waters exhibit a narrow range between 0.6 and 1pmol/kg but are not significantly higher than at depth.Neodymium isotope signatures (ɛNd) vary from unradiogenic values between −16.8 and −14.9 at the surface to more radiogenic values near −11.0 at the bottom of the Labrador Sea mainly reflecting the advection of the Denmark Strait Overflow Water and North East Atlantic Deep Water, the signatures of which are influenced by weathering contributions from Icelandic basalts. Unlike Nd, water column radiogenic Hf isotope signatures (ɛHf) are more variable representing diverse weathering inputs from the surrounding landmasses. The least radiogenic seawater ɛHf signatures (up to −11.7) are found in surface waters close to Greenland and near the Canadian margin. This reflects the influence of recirculating Irminger Current Waters, which are affected by highly unradiogenic inputs from Greenland. A three to four ɛHf unit difference is observed between Denmark Strait Overflow Water (ɛHf∼−4) and North East Atlantic Deep Water (ɛHf∼−0.1), although their source waters have essentially the same ɛNd signature. This most likely reflects different weathering signals of hafnium delivered to Denmark Strait Overflow Water and North East Atlantic Deep Water (incongruent weathering of old rocks from Greenland versus basaltic rocks from Iceland). In addition, the ɛHf data resolve two layers within the main body of Labrador Sea Water not visible in the ɛNd distribution, which are shallow Labrador Sea Water (ɛHf∼−2) and deep Labrador Sea Water (ɛHf∼−4.5). The latter layer was formed between the late 1980’s and mid 1990’s during the last cold state of the Labrador Sea and underwent substantial modification since its formation through the admixture of Irminger Water, Iceland Slope Water and North East Atlantic Deep Water, which is reflected in its less radiogenic ɛHf signature. The overall behavior of Hf in the water column suggests its higher sensitivity to local changes in weathering inputs on annual to decadal timescales. Although application of Hf isotopes as a tracer for global water mass mixing is complicated by their susceptibility to incongruent weathering inputs they are a promising tracer of local processes in restricted basins such as the Labrador Sea.

Extreme drought causes distinct water acidification and eutrophication in the Lower Lakes (Lakes Alexandrina and Albert), Australia

Droughts are set to increase in frequency and magnitude with climate change and water extraction, and understanding their influence on ecosystems is urgent in the Holocene. Low rainfall across the Murray-Darling Basin (MDB) of Australia resulted in an unprecedented water level decline in the Lower Lakes (Lakes Alexandrina and Albert) at the downstream end of the river system. A comprehensive data covering pre-drought (2004–2006), drought (2007–2010) and post-drought (2010–2013) was firstly used to unravel drought effects on water quality in the contrasting main parts and margins of the two Lakes, particularly following water acidification resulting from acid sulfate soil oxidation. Salinity, nutrients and Chl-a significantly increased during the drought in the Lake main waterbody, while pH remained stable or showed minor shifts. In contrast to the Lake Alexandrina, total dissolved solid (TDS) and electrical conductivity (EC) during the post-drought more than doubled the pre-drought period in the Lake Albert as being a terminal lake system with narrow and shallow entrance. Rewetting of the exposed pyrite-containing sediment resulted in very low pH (below 3) in Lake margins, which positively contributed to salinity increases via SO42− release and limestone dissolution. Very acidic water (pH 2–3) was neutralised naturally by lake refill, but aerial limestone dosing was required for neutralisation of water acidity during the drought period. The Lower Lakes are characterized as hypereutrophic with much higher salinity, nutrient and algae concentrations than guideline levels for aquatic ecosystem. These results suggest that, in the Lower Lakes, drought could cause water quality deterioration through water acidification and increased nutrient and Chl-a concentrations, more effective water management in the lake catchment is thus crucial to prevent the similar water quality deterioration since the projected intensification of droughts. A comparative assessment on lake resilience and recovering processes should be undertaken with a post-drought monitoring program.

The spatial spread of schistosomiasis: A multidimensional network model applied to Saint-Louis region, Senegal

Schistosomiasis is a parasitic, water-related disease that is prevalent in tropical and subtropical areas of the world, causing severe and chronic consequences especially among children. Here we study the spatial spread of this disease within a network of connected villages in the endemic region of the Lower Basin of the Senegal River, in Senegal. The analysis is performed by means of a spatially explicit metapopulation model that couples local-scale eco-epidemiological dynamics with spatial mechanisms related to human mobility (estimated from anonymized mobile phone records), snail dispersal and hydrological transport of schistosome larvae along the main water bodies of the region. Results show that the model produces epidemiological patterns consistent with field observations, and point out the key role of spatial connectivity on the spread of the disease. These findings underline the importance of considering different transport pathways in order to elaborate disease control strategies that can be effective within a network of connected populations.

Spatial–Temporal Dynamics of Wetland Vegetation Related to Water Level Fluctuations in Poyang Lake, China

Hydrological properties are driving forces of wetland systems. The influence of water level fluctuations on vegetation distribution is of growing interest as wetlands are increasingly disturbed by climate change and intensive human activity. Based on time series MODIS (Moderate Resolution Imaging Spectroradiometer) imagery from 2000 to 2012, we investigated the spatial–temporal dynamics of wetland vegetation in Poyang Lake using a combined Sen’s slope and Mann–Kendall (MK) test approach, and explored their correlations with water level fluctuations in different hydrological periods. The results showed that more than 34% of wetlands at lower elevations of Poyang Lake had experienced an increasing trend in the enhanced vegetation index (EVI), whereas EVI in about 11% of the wetlands at higher elevations decreased significantly. Responses of grassland area extracted from MODIS EVI were found to be more sensitive to water level fluctuations in the southern lakes. The change rate of grassland area decreased with the rising water level during the rising period, but increased with the rising water level during the retreating period. Correlations between grassland area and water level were much weaker in the dry period. In addition, we found fluctuations of the main water body had negligible effect on grassland area since the water level at Xingzi station was below 14 m. These results provide new insights for predicting future changes of wetland vegetation influenced by the ongoing threats from climate change and human activity, and form a foundation for ecosystem management of Poyang Lake.

The use of phytoplankton as an indicator of internal hydrodynamics of a large seaside reservoir – case of the Sasyk Reservoir, Ukraine

The Sasyk Reservoir, one of the largest seaside reservoirs on the northwest shore of the Black Sea, the former river delta currently detached from the sea with a narrow bar of sediments, was investigated for spatial distribution of water quality characteristics with the use of bioindication method. A three day preliminary sampling campaign of phytoplankton held in the summer 2013 revealed that the reservoir's dominating species belonged to moderate temperature, freshwater, low acidic and low alkaline indicative groups. They suggest standing to slow-moving hydrodynamics of water masses, that contain a medium amount of oxygen. The indices of ecosystem status, such as index of organic pollution according to Watanabe, modification of Sládeček, water quality classes based on saprobity, trophic state indicator groups, nitrogen metabolism indicator groups, as well as Shannon index coincided, showing medium polluted Class III (saprobity) eutrophic water with prevailing moderate concentrations of organically bounded nitrogen. Environmentally homogeneous water masses were dominated with local anomalies on the locations of inflows of waters of different physicochemical characteristics from rivers and the Danube-Sasyk Canal, saline waters from the sea, and nitrogen enriched groundwater from intensive agricultural area. Two types of ecosystems were identified, the one connected with the main water body and the other with the shallows. The sampling was performed in the condition of no outflow, but the wind direction and the wind driven internal dynamics of the reservoir were the major influencing factors for phytoplankton distribution. A gradient of water pollution in the direction of the north–south section of the receiving water from the Danube-Sasyk Canal was revealed. Although the reservoir ecological processes seems to be effective enough in metabolizing the incoming pollution, the symptoms of progressing deterioration of water quality (small-cell forms of organisms) indicate the need for further monitoring and proper management. The bioindicative method appeared to be in some cases more sensitive in ecosystem and abiotic factors analysis then a standard physicochemical analysis, which creates a ground for further developing of its predictive potential.

Nutrient load concept-reservoir vs. bay impacts: a case study from a semi-arid watershed.

Large flow-through reservoirs and lakes possess environmental gradients and monitoring programs are mostly adapted for cost and time effectiveness. Bay areas are often more isolated from the main water body and are likely to have unobserved different environmental processes and impacts. This study was performed at the Itaparica Reservoir, São Francisco River, located in semi-arid Northeast Brazil, with dendritic form. Water residence time in the Icó-Mandantes Bay was estimated by hydrodynamic flow and transport simulations. The P-chlorophyll a relationship was used to develop the P use efficiency coefficient for critical P load estimation of 25 μg P L-1. Phosphorus sources and input rates into a bay and the respective reservoir were calculated and compared regarding their different origins for the period after flooding (1988) and for 2013. After impoundment, the P load highly exceeded the carrying capacity because of leaching and mineralization processes. In 2013, P inputs were still above this threshold, whereas inflow and sub-basin P export during the rainy season were crucial. But eutrophication processes have increased in the bay relative to the main water body. Hence, water in hydraulic isolated parts is prone to eutrophication processes, thus, bays have to be specially considered in water resource management.

Rapid survey of Dragonflies (Insecta: Odonata) of Kribi forest and Campo Ma'am national Park, Southern Cameroon

A five day survey was carried out to assess the odonate fauna associated with the riverine sections of two forests (Kribi Forest and Campo Ma’am National Park) of southern Cameroon. The primary objective of the study was to determine the species composition and community structure of the odonate fauna occurring in the forests. The goal is to infer the health status of the two forests. Three study sites were selected, one in each of the main water bodies in the forests (Rivers Kienke and Linde in Kribi forest, and River Bitande in Campo Ma’am National Park). All the specimens collected were identified to the lowest taxonomic level. A total of one hundred and ninety four (194) individuals of Odonata were collected in the forests comprising 10 families, 24 species of Anisoptera and 30 species of Zygoptera. Anthropogenic activities were less prevalent at Campo Ma’am National Park, an area in which all the 10 families were incidentally recorded. The community structure of the southern forest revealed that only River Bitande with Shannon-Wiener diversity index (H`) of 3.80 was having a stable environmental condition. Others were close to stable condition (River Kienke H` 2.99 and River Linde H` 2.95) with mild disturbance caused by human activity. Simpson index range (0.94 – 0.98) at the three study sites revealed that the vegetation was matured and stable. The distribution of dragonflies and damselflies revealed a stable environment (Evenness 0.90 – 0.95). Kribi Forest appears to be more impacted by anthropogenic activities as fewer (six) families were recorded there. The relative distribution of the species in the two forest ecosystems seemed to have some relationship with human interference therein. Key Words : Damselfly, Dragonfly, Diversity, Forest, River

Spatial and temporal assessment of environmental contaminants in water, sediments and fish of the Salton Sea and its two primary tributaries, California, USA, from 2002 to 2012

The Salton Sea, the largest inland surface water body in California, has been designated as a sensitive ecological area by federal and state governments. Its two main tributaries, the New River and Alamo River are impacted by urban and agriculture land use wastes. The purpose of this study was to temporally and spatially evaluate the ecological risks of contaminants of concern in water, sediments and fish tissues. A total of 229 semivolatile organic compounds and 12 trace metals were examined. Among them Selenium, DDTs, PAHs, PCBs, chlorpyrifos and some current-use pesticides such as pyrethroids exceeded risk thresholds. From 2002 to 2012, measurements of chlorpyrifos in sediments generally declined and were not observed after 2009 at the river outlets. In contrast, pyrethroid concentrations in sediments rose consistently after 2009. In water samples, the outlets of the two rivers showed relatively higher levels of contamination than the main water body of the Salton Sea. However, sediments of the main water body of the Salton Sea showed relatively higher sediment concentrations of contaminants than the two rivers. This was particularly true for selenium which showed reductions in concentrations from 2002 to 2007, but then gradual increases to 2012. Consistent with water evaluations, contaminant concentrations in fish tissues tended to be higher at the New River boundary and at the drainage sites for the Alamo River compared to sites along each river. The persistent contaminants DDTs, PAHs, chlorpyrifos and several pyrethroid insecticides were associated with the toxicity of sediments and water collected from the rivers. Overall, assessment results suggested potential ecological risk in sediments of the Salton Sea as well as in water and fish from the two rivers.

A baseline classification of riparian woodland plant communities in the Okavango Delta, Botswana

In the Okavango Delta information on the riparian woodland vegetation community composition and distribution is generally lacking. Past studies in the Delta were mainly focused on the quantitative classification of seasonal floodplain herbaceous vegetation communities. The aim of this study was to determine riparian woodland vegetation communities in the Okavango Delta. Vegetation sampling was conducted in 20 m × 50 m randomly placed plots. The plots were placed along a gradient from the main water body to the drier fringe of the riparian zone. Plant species present in each plot were recorded with their estimated percentage cover using the Braun–Blanquet cover abundance scale. Hierarchical cluster analysis was used to determine vegetation communities. Indicator species analysis was used to calculate indicator values for species groups defined from the cluster analysis. Plant species and diversity were determined for each vegetation cluster. Multi-response permutation procedures (MRPP) were used to determine significance of differences between communities. The Kruskal–Wallis test was used to compare species diversity and richness between vegetation communities. Four vegetation communities were identified: Croton megalobotrys– Hyphaene petersiana, Vachellia erioloba–Diospyros lycioides, Syzygium cordatum–Phoenix reclinata and Garcinia livingstonei–Senegalia nigrescens. In this classification, the Syzygium cordatum–Phoenix reclinata and Garcinia livingstonei–Senegalia nigrescens plant communities are found in frequently flooded regions, whereas the Croton megalobotrys–Hyphaene petersiana and Vachellia erioloba–Diospyros lycioides are in occasionally flooded regions. Total number of species was highest in the Garcinia livingstonei–Senegalia nigrescens and lowest in the Syzygium cordatum–Phoenix reclinata vegetation communities. The MRPP showed that there was significant (p < 0.05) differences between vegetation communities. Species diversity and richness were significantly (p < 0.05) higher in the Garcinia livingstonei–Senegalia nigrescens vegetation community. This study provided an inventory of riparian woodland plant communities, which can be used as a vital monitoring tool of vegetation change in the Okavango Delta.

Anticipatory Real-time Management in the Lake IJssel: Implementation and Practical Application

In the Netherlands, flood protection has always been a key issue to protect settlements against storm surges and riverine floods. In addition, with the expected effects of climate change being more extreme, there is a need to address not only floods, but also droughts. In doing this, it is essential to adopt integrated and anticipatory techniques which are able to manage both.In our research we present the application of such an anticipatory real-time control technique for the daily management of three connected lakes, together forming a large fresh-water reservoir in the hearth of the Netherlands. The main controlled water bodies are the Lake IJssel, which is the largest lake in Western Europe, and the neighboring Lake Marker and the Lakes Veluw. The area has a vital function both in preventing floods en droughts in the Netherlands: the lakes receive water from the River IJssel and from the neighboring water systems, managed by local Regional Water Authorities (Waterboards). Lake IJssel discharges during low tide in the downstream Wadden Sea. An anticipatory approach is very beneficial for this water system in order to release water in anticipation of high inflows or reduced discharge potential due to high sea levels. During droughts, real-time control techniques support the optimal distribution of limited available fresh water.In collaboration with the National Water Authority (Rijkswaterstaat), an advisory module based on Model Predictive Control has now been implemented in the Operational Management System for Regulated Water Bodies for the Netherlands (RWsOS-IWP) and produces a daily operational advice for the management of the structures regulating the lakes. We explain how we set-up the prediction model (RTC-Tools) into the Operational System (Delft-FEWS), which real time forcing are used and how the different optimization goals are implemented. Special attention is paid to the presentation of the complex output of the advisory modules to the operators.

Length-weight relationships of 15 fish species from Tembeling River, Pahang, Malaysia

Summary This study reports the length–weight relationships (LWR) of 15 fish species from Tembeling River, Pahang, Malaysia. The river flows adjacent to the National Park, Pahang, and supplies fishes for local consumption. In addition, this river also functions as a main water body for protection and breeding of commercial fish species. A total of eight LWRs were unknown to FishBase, and five new maximum lengths were identified from the study.

Land cover changes assessment using object‐based image analysis in the Binah River watershed (Togo and Benin)

AbstractIn this study, land cover changes between 1972 and 2013 were investigated in the Binah River watershed (North of Togo and Benin) using remote sensing and geographic information system technologies. Multitemporal satellite images—Landsat MSS (1972), TM (1987), and OLI‐TIRS (2013)—were processed using object‐based image analysis and post–classification comparison methods including landscape metrics and changes trajectories analysis. Land cover maps referring to five main land cover classes, namely, agricultural land, forest land, savannah, settlements, and water bodies, were produced for each acquisition date. The overall accuracies were 76.64% (1972), 83.52% (1987), and 88.84% (2013) with respective Kappa statistics of 0.69, 0.78, and 0.86. The assessment of the spatiotemporal pattern of land cover changes indicates that savannah, the main vegetation type, has undergone the most dominant change, decreasing from 67% of the basin area in 1972 to 56% in 1987 and 33% in 2013. At the same time, agricultural land has significantly increased from 15% in 1972 to 24% in 1987 and 43% in 2013, while some proportions of agricultural land were converted to savannah relating to fallow agriculture. In total, more than 55% of the landscape experienced changes between 1972 and 2013. These changes are primarily due to human activities and population growth. In addition, agricultural activities significantly contributed to the increase in the number of patches, degree of division, and splitting index of forest and savannah vegetations and the decrease in their effective mesh sizes. These results indicate further fragmentation of forest and savannah vegetations between 1972 and 2013. Further research is needed to quantitatively evaluate the influences of individual factors of human activities and to separate these from the impacts of climate change‐driven disturbances.

Spatial Distribution Of Lead, Zinc And Chromium In The Bottom Deposits Of Lake Sunia

Abstract Various elements are accumulated in bottom deposits in concentrations that significantly exceed the levels observed in lake water. Under certain conditions, this can lead to secondary contamination of water, posing threat to aquatic organisms. The aim of this study was to evaluate the spatial distribution of Pb, Zn and Cr pollutants in the bottom deposits of Lake Sunia. The investigated water body is situated in the Olsztyn Lakeland western part of the Masurian Lakeland), approximately 30 km north of the city of Olsztyn, in the municipality of Swiatki. The lake has a total area of 111.6 ha and a maximum depth of 8.8 m. The inflow to and the outflow from lake are situated in its south-western and north-western part, respectively. The lake features a bay which is separated from the main water body by a shallow zone. Its catchment area comprises mainly agricultural land. The total area of supply of lake is 450 ha of which inflow catchment area is 70 ha. Most of the catchment area is agricultural land (91%), and in particular arable land, the rest of the area (5%) are the barren, and trees (4%). the area of the lake is dominated by power-sandy loam soil in the passing sands and clay loam strong little sandy. In terms of particle size are a summary of the soil that is difficult permeable to water and nutrients. Taking into account the valuation of soil classification in the vast quantities of soil are included in the class IVa, IIIa and IIIb. The average content of organic matter in the lake was determined at 24%. Significant accumulation of organic matter results from intense inflow of biogenic substances from farmed areas in the catchment. The average concentrations of trace elements in the analyzed water body were arranged in the following series: Cr &lt; Pb &lt; Zn, and their ratios were determined at 8.1 &lt; 22.9 &lt; 45.2. Higher levels of heavy metals were observed the profundal zone, whereas lower concentrations of the analyzed elements were noted in littoral zone sediments.

Out of the Black Sea: phylogeography of the invasive killer shrimp Dikerogammarus villosus across Europe.

The amphipod Dikerogammarus villosus has colonized most of the European main inland water bodies in less than 20 years, having deteriorating effect on the local benthic communities. Our aim was to reveal the species phylogeography in the native Black Sea area, to define the source populations for the colonization routes in continental Europe and for the newly established UK populations. We tested for the loss of genetic diversity between source and invasive populations as well as along invasion route. We tested also for isolation by distance. Thirty three native and invasive populations were genotyped for mtDNA (COI, 16S) and seven polymorphic nuclear microsatellites to assess cryptic diversity (presence of deeply divergent lineages), historical demography, level of diversity within lineage (e.g., number of alleles), and population structure. A wide range of methods was used, including minimum spanning network, molecular clock, Bayesian clustering and Mantel test. Our results identified that sea level and salinity changes during Pleistocene impacted the species phylogeography in the Black Sea native region with four differentiated populations inhabiting, respectively, the Dnieper, Dniester, Danube deltas and Durungol liman. The invasion of continental Europe is associated with two sources, i.e., the Danube and Dnieper deltas, which gave origin to two independent invasion routes (Western and Eastern) for which no loss of diversity and no isolation by distance were observed. The UK population has originated in the Western Route and, despite very recent colonization, no drastic loss of diversity was observed. The results show that the invasion of the killer shrimp is not associated with the costs of loosing genetic diversity, which may contribute to the success of this invader in the newly colonized areas. Additionally, while it has not yet occurred, it might be expected that future interbreeding between the genetically diversified populations from two independent invasion routes will potentially even enhance this success.