Mercury in the water of small rivers of the Onega Bay basin of the White Sea

The results of the expeditionary studies of the mercury behavior in the water of small rivers of the Onega Bay basin of the White Sea are presented. Priority forms of mercury migration have been identified and the forms of its location along the trunk of the Kyanda River have been calculated. The relationship between the content of various forms of mercury on the one hand and salinity, pH, Eh waters on the other has been analyzed. The influence of hydrological phases on the transformation of inorganic forms of mercury has been revealed. Differences in the levels of content of dissolved mercury and its connection with the salinity in the extuar areas of the marginal filters of the Subarctic rivers in natural conditions and the environment of anthropogenic impact were established.

Shannon Entropy for Measuring Spatial Complexity Associated with Mean Annual Runoff of Tertiary Catchments of the Middle Vaal Basin in South Africa

This study evaluates essentially mean annual runoff (MAR) information gain/loss for tertiary catchments (TCs) in the Middle Vaal basin. Data sets from surface water resources (WR) of South Africa 1990 (WR90), 2005 (WR2005) and 2012 (WR2012) referred in this study as hydrological phases, are used in this evaluation. The spatial complexity level or information redundancy associated with MAR of TCs is derived as well as the relative change in entropy of TCs between hydrological phases. Redundancy and relative change in entropy are shown to coincide under specific conditions. Finally, the spatial distributions of MAR iso-information transmission (i.e., gain or loss) and MAR iso-information redundancy are established for the Middle Vaal basin.

Co-occurrence patterns of fish communities in littorals of three floodplain lakes of the Orinoco River, Venezuela

The co-occurrence patterns of fish communities in the littorals of three lagoons of the Orinoco River floodplain in Venezuela were studied during four hydrological phases: low, rising, high and falling waters, from 2008–2009, using null models. The analyses were made separately for each floodplain lake and for each habitat type within them. During low waters only one lake showed a segregated pattern in beaches covered with leaf litter, whereas in the other floodplain lakes the communities were randomly assembled in all habitats during the four hydrological phases. Despite the absence of a significant overall structure, several significantly aggregated and segregated species pairs were observed in the three lakes. The temporal variation might be the main factor responsible for the co-occurrence patterns observed in these floodplain lakes due to the periodic reshuffling of littoral habitats.

Abiotic variability among different aquatic systems of the central Amazon floodplain during drought and flood events

This paper examines water properties from lakes, (depression lakes, sensu Junk et al., 2012), channels (scroll lakes with high connectivity, sensu Junk et al., 2012) and paleo-channels (scroll lakes with low connectivity-sensu Junk et al., 2012, locally called ressacas) located in Mamirauá Sustainable Development Reserve, in Central Amazon floodplain, Amazonas, Brazil. We analysed surface temperature, conductivity, pH, dissolved oxygen, turbidity, transparency, suspended inorganic and organic matter, chlorophyll-a, pheophytin, total nitrogen, total phosphorus, organic and inorganic carbon in 2009 high water phase, 2009 and 2010 low water phases. Multivariate statistical analyses of 24 aquatic systems (6 ressacas, 12 lakes and 6 channels, 142 samples) were applied to the variables in order to: 1) quantify differences among aquatic system types; 2) assess how those differences are affected in the different phases of the hydrological year. First, we analysed the entire set of variables to test for differences among phases of the hydrological year and types of aquatic systems using a PERMANOVA two-way crossed design. The results showed that the all measured limnological variables are distinct regarding both factors: types of aquatic systems and hydrological phases. In general, the magnitude and amplitude of all variables were higher in the low water phase than in the high water phase, except for water transparency in all aquatic system’s types. PERMANOVA showed that the differences between aquatic system’s types and hydrological phases of all variables were highly significant for both main factors (type and phase) and for the type x phase interaction. Limnological patterns of Amazon floodplain aquatic systems are highly dynamic, dependent on the surrounding environment, flood pulse, main river input and system type. These patterns show how undisturbed systems respond to natural variability in such a diverse environment, and how distinct are those aquatic systems, especially during the low water phase. Aquatic systems in Mamirauá floodplain represent limnological patterns of almost undisturbed areas and can be used as future reference for comparison with disturbed areas, such as those of the Lower Amazon, and as a baseline for studies on the effects of anthropogenic influences and climate change and on Amazon aquatic ecosystem.

Dynamics of the Copper Content in the Podborenka River Surface Water

Outcomes of studying of the urbanized environment impact on the status of the Podborenka River that is the part of the catchment area of the Izhevsk Reservoir, an important city-forming body, are presented. The river hydrological and hydro/chemical characteristics and the copper content dynamics in surface waters during the main hydrological phases have been discussed. It has been found that the main mass of copper is supplied into the water body from the local relief with the atmospheric precipitation surface runoff.

Diel responses of phytoplankton of an Amazon floodplain lake at the two main hydrological phases

AIM: This study examines the short-term changes of phytoplankton in an oxbow lake on the floodplain of the Acre River, Amazonia, Brazil. METHODS: Samples were taken with a Van Dorn bottle, at three depths (surface, middle and bottom), in two periods (low waters and high waters), for seven consecutive days in two schedules, night and morning. RESULTS: Phytoplankton was represented by 198 taxa and the Class Euglenophyceae, with 62 taxa, was the best-represented group in both periods. There were abrupt changes in the community during the high waters (potamophase). During this period, in conditions of partial atelomixis, we recorded higher values of phytoplankton biovolume and dominance of Gonyostomum semen (Ehr.) Dies. (Raphidophyceae). CONCLUSIONS: In the low waters (limnophase), conditions in the lake were more stable, the diversity and rate of change in the community were lower, and the frequent periods of stratification and mixing were responsible for the dominance of Geitlerinema sp. (Cyanobacteria).