Multi-Temporal Surface Water Classification for Four Major Rivers from the Peruvian Amazon

We describe a new minimum extent, persistent surface water classification for reaches of four major rivers in the Peruvian Amazon (i.e., Amazon, Napo, Pastaza, Ucayali). These data were generated by the Peruvian Amazon Rural Livelihoods and Poverty (PARLAP) Project which aims to better understand the nexus between livelihoods (e.g., fishing, agriculture, forest use, trade), poverty, and conservation in the Peruvian Amazon over a 35,000 km river network. Previous surface water datasets do not adequately capture the temporal changes in the course of the rivers, nor discriminate between primary main channel and non-main channel (e.g., oxbow lakes) water. We generated the surface water classifications in Google Earth Engine from Landsat TM 5, 7 ETM+, and 8 OLI satellite imagery for time periods from circa 1989, 2000, and 2015 using a hierarchical logical binary classification predominantly based on a modified Normalized Difference Water Index (mNDWI) and shortwave infrared surface reflectance. We included surface reflectance in the blue band and brightness temperature to minimize misclassification. High accuracies were achieved for all time periods (>90%).

BIVALVE MOLLUSCS (BIVALVIA: UNIONIDAE, DREISSENIDAE, SPHAERIIDAE) OF UDMURTIA

The results of the studies of fauna of bivalve molluscs of Udmurt Republic are summarized. The annotated check-list of species of bivalve molluscs of the waterbodies of Udmurtiya is presented. After examination of own collections and critical assessment of published data, 26 species of bivalves from 74 localities (14 rivers, 2 reservoirs, 8 pounds and 2 oxbow lakes) have been included into the final list. In studied region 11 species of bivalves are recorded for the first time. From the zoogeographical point of view most species belong to the European-Siberian faunistic group (46 %), also a considerable part of fauna are European species (26,9% of overall species composition), which are located in the region at the Eastern border of the range.

The importance of oxbow lakes in the floodplain storage of pollutants

Oxbow lakes are important stores for fine-grained sediment, which potentially makes them critical sinks for sediment-associated pollutants. We leverage an exhaustive public archive of coring data, supplemented by our data collection, to provide a quantitative assessment of the role of oxbows as off-channel sinks. We investigated loading trends of sediment-sorbed polychlorinated biphenyls (PCBs) within oxbows of the Housatonic River, an actively meandering river in western Massachusetts, USA. Our results reveal the efficiency of oxbows as sinks, with average PCB concentrations (14.8 ppm) that are nearly twice that of the surrounding floodplain (7.56 ppm). Even though the 5.83 km2 floodplain is the largest sink of PCB-laden material, storing as much as 14.1 t of PCBs or 2.42 g m–2, oxbows store more than 20% of all PCBs (3.63 t of PCBs or 11.2 g m–2) while making up just over 5% of the floodplain surface area. Nearly 85% of the oxbow storage of PCBs occurs within the first 50 m of floodplain, making clear the significance of regular oxbow production to the off-channel storage of sediment-associated pollutants.

Environmental Characterization of Two Ecologically Distinct Gangetic Oxbow Lakes Using Zooplankton Taxonomic Indices In Ecological Monitoring: A Comparative Approach

In recent years closed and seasonally open oxbow lakes and river floodplains are subjected to eutrophication due to disconnection from river that compromises the hydro-ecological functions. This requires systematic studies to assess the ecological health of the water bodies using different indices and suggest appropriate strategies to manage the resources. The zooplanktons are closely link with surrounding environment throughout their life cycles and change rapidly in their growth and population when changes occurs in the surrounding, hence act as potential indicator of eutrophication. The present study examined the assemblage pattern of zooplankton community and trophic state of two ecologically distinct oxbow lakes based on eco-hydrological characteristics and community structure of rotifers and planktonic crustaceans seasonally over a period of 2 years. Comprehensive trophic state index (mTSI), rotifer trophic state index (mTSIROT) and Crustacean based indices (TSICR) were used to assess the degree of eutrophication. The Kruskal-Wallis test confirmed the heterogeneity of the eco-hydrological factors between the oxbow lakes. A total of 68 zooplankton species were identified of which rotifers (69%), cladocerans (18%), copepods (3%), ostacods (3%) and protozoans (7%). Seasonal fluctuation of relative abundance and frequency of species in both lakes have been well presented. Both lakes showed transition from high meso-eutrophic to moderately eutrophic state with mTSI, mTSIrot and mTSIcr values of 54.90±11.71 and 56.95±15.64, 59.55±4.54 and 60.26±4.48, 55.79±4.76 and 60.00±4.03 in Khalsi (seasonally open) and Akaipur (closed) respectively. The Canonical Correspondence analysis (CCA) revealed water quality parameters comparison NO3-N, water temperature and pH have contributed more in enhancement of abundance of eutrophication indicator species Brachionus and Keratella. The TSIs values indicated a prompt aquaculture fisheries management measures like stocking of planktivorous fish (Labeo catla and Puntius sp.) for both the lakes before they reach in plunged state at which their restoration might become a challenge. An overview of worldwide use of rotifer and crustacean based indices in assessment of TSI has also been synthesized. The use of these zooplankton indices to evaluate the trophic status of the ecologically distinct lakes is highly recommended for water quality assessment and management. Based on this study strategies could be developed to plan and manage floodplain oxbow lakes for fisheries enhancement programme as well as as conservation of biodiversity.

Supplemental Material: The importance of oxbow lakes in the floodplain storage of pollutants

Radiometric data from Woods Pond, Massachusetts, loss-on-ignition data from cores collected along transect T1, and coordinates of core locations.<br>

Supplemental Material: The importance of oxbow lakes in the floodplain storage of pollutants

Radiometric data from Woods Pond, Massachusetts, loss-on-ignition data from cores collected along transect T1, and coordinates of core locations.<br>

Present tendencies in landscape planning and recognition of the opinion of local citizens on the example of the Tiszazug

A survey based on online and face-to face interviews with 104 persons who live in the Tiszazug in the central part of the Great Hungarian Plain. According to the answers the character of the landscape here would change dramatically by disappearance of oxbow lakes, floodplain forests and vineries. The decreasing population and aging of the citizens result in decreasing intensity of landuse, increasing number of abandoned buildings and the attractiveness of the landscape is spoiled by illegal waste disposals and weedy water banks.

An availibility of arctic lakes organic sediments to microbial degradation: a laboratory incubation experiment

The water ecosystems of the Arctic region are most vulnerable to modern climatic changes since the global biogeochemical processes mostly occur on the territories of the permafrost zone. Aquatic ecosystems show a high degree of sensitivity to climatic changes; both in these and in other ecosystems, the biogeochemical processes are intense. These water bodies are located in the permafrost zone, which is vulnerable to temperature increases. The paper gives new insights into the fundamental research question of how fast the organic matter of thawing permafrost can be converted to greenhouse gases emitted into the atmosphere (CO2, CH4). We aimed to assess the microbial response and the associated release of CO2 and CH4 from the Arctic lakes in response to temperature increase. We investigated lakes located in the Lena River delta in the Samoylov Island, Russia, at 72° 22′ N, 126° 28′ E. Bottom sediments from three thermokarst and three oxbow lakes were anaerobically incubated in the laboratory at two temperature regimes (at 4 °C and at 25 °C). All the oxbow lakes have shown similar dynamics of methane emission both at low temperatures (4 °C) and at high temperatures (25 °C). The shift of carbon isotopic composition in methane has indicated that methane is emitted in all the oxbow lakes with a similar composition of microbial communities. In the thermokarst lakes, the emission of methane in the sediments proceeded differently at low and at high temperatures. These results have indicated a dissimilar composition of methanogenic / methanotrophic populations in the thermokarst and oxbow lakes. In both cases, the temperature increase caused a growth in methane emission from the sediments of the Arctic lakes. The thermokarst lakes will make a greater contribution to methane emission than the oxbow lakes. Thus, it is believed that the emission of methane from the thermokarst lakes will rise from 6 to 46 times due to ambient temperature increase. Methane emission from the oxbow lakes will grow from 1.8 to 7.6 times. Our results suggest that with the global warming both thermokarst and oxbow lakes could become a great source of methane emission into the atmosphere.

Wetland dynamics at the transition between humid and semiarid environments of inland Brazil: São Francisco river morphodynamics and implications for the Pandeiros wetland.

&lt;p&gt;The presence of wetlands as a result of local fluvial and hydrological conditions constitutes a frequently observed feature of such rivers. Therefore, they are important elements of the basin, because besides functioning as buffer zones for CO&lt;sub&gt;2&lt;/sub&gt; and sediments they also house important ecosystems, playing an important role in the control of water circulation.&amp;#160;Brazilian wetlands have different typologies and sizes, varying from huge swamplands such as the Pantanal do Mato Grosso, to flooded savannas called &amp;#8220;veredas&amp;#8221; or oxbow lakes. Their distribution in inland areas depends on the variety of flood pulses mainly linked to seasonality with the presence of distinct dry and wet seasons (Junk et al., 1989).&amp;#160;This strong seasonality affects the S&amp;#227;o Francisco River (SFR), the 4&lt;sup&gt;th&lt;/sup&gt; largest river in Brazil, which has frequent marginal lakes and swamps as it passes through five Brazilian states. This research aims to analyze the effect of the variation of the SFR level from 1925 to 2018, on the flow of the Pandeiros River which is one of many tributaries on the left side of SFR and on its wetland (&amp;#8220;Pantanal Mineiro&amp;#8221;). This wetland is hydrogeomorphologically linked to the SFR and receives water inputs during SFR flood periods.&amp;#160;Measurements of the SFR water level performed once daily in the morning were obtained from gauging station n&lt;sup&gt;o&lt;/sup&gt; 44200000 belonging to the Companhia de Pesquisa de Recursos Minerais (CPRM) [altitude 445 m; 15&amp;#176;56'57.84&quot;S; 44&amp;#176;52'4.68&quot;W. The hydrological year starts at the end of the dry season on October 1st. Time series analyses (level duration curve, Seasonal Trend Decomposition (STL) of the daily level data, monthly level, mean, maximum, minimum level for each day of the year) were conducted to describe the hydrological regime and to assess temporal changes of the SFR levels and how these affect the magnitude, frequency and duration of flooding of the Pandeiros&amp;#8217;s River wetland.&amp;#160;Field observations (March 14, 2018) show that when SFR, which is Pandeiro&amp;#8217;s base level, reaches a level of 5.0 m this leads to flooding conditions of the Pandeiros River wetland.&amp;#160;Over the full period of record (1925-2018) the average level of the SFR was 3.86 m, with a minimum annual average of 2.43 m during the dry season (winter) and maximum of 5.98 m during the wet season (summer), with an average annual range of 3.55 m between both seasons. The SFR was above the 5.0 m threshold flooding level for 20% of the time 1925-2018, which corresponds to an average of 77.8 days of flooding per year in the wetland. The longest period of inundation was 178 days in 1926, when the SFR reached its maximum recorded level, and the shortest was 1 day in 2015, when it reached its minimum. The number of days per year of inundation have decreased over the full record, but that this is mainly due to a significant decrease since 1985. Prior to this, cyclic differences between wetter (1925 and 1985) and drier periods (1925 to 1945, 1945 to 1965) are observed.&lt;/p&gt;