scholarly journals An assessment of the factors determining rotifer assemblage in river-lake systems: the effects of seasonality and habitat

2019 ◽  
Vol 36 ◽  
pp. 1-5
Author(s):  
Moacyr Serafim-Júnior ◽  
Gilmar Perbiche-Neves ◽  
Fabio Lansac-Toha
Keyword(s):  
Species Richness ◽  
Aquatic Macrophytes ◽  
Hydrological Cycle ◽  
High Water ◽  
Water Levels ◽  
Natural Environments ◽  
Ecological Attributes ◽  
Lake System ◽  
The Mean ◽  
Lake Systems

Zooplankton exhibit several trends of variation in space and time, and these trends can be more evident in natural environments without anthropic perturbations. Examples of anthropic factors are climate change, eutrophication and construction of reservoirs. This study evaluated the influence of three factors – seasonality, type of environment and the presence of aquatic macrophytes – on various ecological attributes of rotifers in a river-lake system located in the Paraná River floodplain. Monthly samplings were conducted during 1993 and 1994. The mean species richness per sample was 60 species. The seasonality and the type of environment influenced the ecological attributes of rotifer assemblages, while the presence or absence of aquatic macrophytes did not. Species richness was highest in the lake system and during the months when water levels were low. Multivariate analysis indicates a small group of species associated with the low water-level phase. In contrast, many species were associated with high water levels or increasing water levels. The seasonal variation of hydrological cycle and the type of environment are the most important factors for rotifer structure in natural conditions.

scholarly journals PRE- and POST-STORM LiDAR SURVEYS FOR ASSESSMENT OF IMPACT ON COASTAL EROSION

2019 ◽  
Vol XLII-3/W8 ◽  
pp. 261-266
Author(s):  
A.-L. Montreuil ◽  
M. Chen ◽  
A. Esquerré ◽  
R. Houthuys ◽  
R. Moelans ◽  
...  
Keyword(s):  
Management Practices ◽  
Morphological Changes ◽  
Storm Surges ◽  
High Water ◽  
Water Levels ◽  
Airborne Lidar ◽  
Coastline Change ◽  
The Mean ◽  
The Impact

<p><strong>Abstract.</strong> Sustainable management of the coastal resources requires a better understanding of the processes that drive coastline change. The coastline is a highly dynamic sea-terrestrial interface. It is affected by forcing factors such as water levels, waves, winds, and the highest and most severe changes occur during storm surges. Extreme storms are drivers responsible for rapid and sometimes dramatic changes of the coastline. The consequences of the impacts from these events entail a broad range of social, economic and natural resource considerations from threats to humans, infrastructure and habitats. This study investigates the impact of a severe storm on coastline response on a sandy multi-barred beach at the Belgian coast. Airborne LiDAR surveys acquired pre- and post-storm covering an area larger than 1 km<sup>2</sup> were analyzed and reproducible monitoring solutions adapted to assess beach morphological changes were applied. Results indicated that the coast retreated by a maximum of 14.7 m where the embryo dunes in front of the fixed dunes were vanished and the foredune undercut. Storm surge and wave attacks were probably the most energetic there. However, the response of the coastline proxies associated with the mean high water line (MHW) and dunetoe (DuneT) was spatially variable. Based on the extracted beach features, good correlations (r>0.73) were found between coastline, berm and inner intertidal bar morphology, while it was weak with the most seaward bars covered in the surveys. This highlights the role of the upper features on the beach to protect the coastline from storm erosion by reducing wave energy. The findings are of critical importance in improving our knowledge and forecasting of coastline response to storms, and also in its translation into management practices.</p>

GRUPOS FUNCIONAIS FITOPLANCTÔNICOS EVIDENCIAM DIFERENÇAS AMBIENTAIS EM UMA PLANÍCIE DE INUNDAÇÃO TEMPERADA

2021 ◽  
Vol 25 (03) ◽  
pp. 648-661
Author(s):  
Felipe Morais Zanon ◽  
◽  
Patrícia Iatskiu ◽  
Michael Joseph Lemke ◽  
Luiz Felipe Machado Velho ◽  
...  
Keyword(s):  
Species Richness ◽  
Primary Productivity ◽  
Hydrological Cycle ◽  
Biogeochemical Cycles ◽  
Water Levels ◽  
Illinois River ◽  
River Floodplain ◽  
Flood Pulses ◽  
High Turbidity

Floodplain environments have high biodiversity and provide many ecosystem services maintained by the flood pulses. The phytoplankton is essential to the functioning of these ecosystems, acting upon primary productivity and biogeochemical cycles. We evaluated phytoplankton in a river-lake flood system (Illinois River floodplain-USA) during a hydrological cycle and compared the taxonomic (species) and functional (morphologic-based functional groups – MBFG) approaches. As expected, greater species richness was registered in the river and higher biovolume in the lake, as well as the predominance of different MBFGs in each environment. Furthermore, seasonality drove richness and biovolume temporal variation due to the higher water levels during spring. The MBFG IV (i. e. without specialized traits), V (phytoflagellates) and VI (diatoms) were more important for richness and biovolume in both environments. We reinforce the fundamental role of the hydrodynamics characteristics, with higher phytoplankton biovolume values in the lake. Using MBFG resulted in a better explanation to the phytoplankton-environment relationship. Constant water column mixture and high turbidity selected species with traits (e.g. small size, presence of silica) specifically adapted to these conditions.

scholarly journals Stability and spatio-temporal structure in fish assemblages of two floodplain lagoons of the lower Orinoco River

2009 ◽  
Vol 7 (4) ◽  
pp. 719-736 ◽  
Author(s):  
Nirson González ◽  
Carlos Lasso ◽  
Judith Rosales
Keyword(s):  
Aquatic Vegetation ◽  
Fish Assemblages ◽  
Hydrological Cycle ◽  
Temporal Structure ◽  
Biotic Interactions ◽  
High Water ◽  
Water Phase ◽  
Fish Assemblage Structure ◽  
Biological Interactions ◽  
The Mean

Fish assemblage structure and variability were analyzed in two floodplain lagoons (Las Arhuacas and Los Cardonales) along the lower Orinoco over a hydrological cycle. Every three months during continuous three-day sampling, experimental gill nets (5 to 12.5 cm of mesh opening) and 1 mm-mesh seine nets were utilized according to the types of habitats presents. A total of 133 fish species were found in Las Arhuacas and 95 species in Cardonales. Fifty five and 17 species were exclusive to Las Arhuacas and Los Cardonales respectively, and 77 were common to both lagoons. In Las Arhuacas, the most speciesrich orders were Characiformes, Siluriformes, Perciformes and Gymnotiformes and in Los Cardonales, the most species-rich orders were Characiformes, Siluriformes, Clupeiformes and Perciformes. The richness, abundance and biomass were significantly higher (p < 0.001) in Arhuacas than in Cardonales. In general, the fishes assemblage was highly variable during the high water phase and moderately stable during low water phase in both lagoons, with more stability or less variability in Cardonales than Arhuacas. Also, there were significant differences in the fish assemblages between the two lagoons, mainly during low waters (ANOSIM; p < 0.001). The species that contributed most to the mean dissimilarity between the lagoons were Hypostomus argus, Aphanotorulus ammophilus, Potamorhina altamazonica, Prochilodus mariae, Loricaria gr. cataphracta, Oxydoras sifontesi, Hydrolycus armatus, Hyphopthalmus edentatus and Pterodoras rivasi. The last four species were more commonly collected in Los Cardonales. Also, the species of small size (mainly SL < 5 cm) such as Rhinosardinia amazonica, Moenkhausia sp. 1 "lepidura", Moenkhausia sp. 2, Aphyocharax alburnus, Characidium sp. 1, Moenkhausia sp. 3, Exodon paradoxus and Roeboides dientonito contributed to the mean dissimilarity among the beach and aquatic vegetation habitats. The patterns of the species assemblage organization were related to the dynamics of the floods. Non-random (i. e., deterministic) associations between species caused by the selection of habitats and/or to biological interactions, apparently were more common during low waters when there is an increased density of fish and so the biotic interactions are intensified. Stochastic associations, on the other hand, seemed to be more common during high water when species are more dispersed.

Number, seasonal movements, and residency characteristics of river dolphins in an Amazonian floodplain lake system

2004 ◽  
Vol 82 (8) ◽  
pp. 1307-1315 ◽  
Author(s):  
A R Martin ◽  
V M.F da Silva
Keyword(s):  
Site Fidelity ◽  
Animal Movement ◽  
Water Levels ◽  
Seasonal Migration ◽  
Floodplain Lake ◽  
Lake System ◽  
Inia Geoffrensis ◽  
Lake Systems ◽  
Permanent Residents

The size and structure of a community of Amazon river dolphins or botos, Inia geoffrensis (de Blainville, 1817), was investigated using boat surveys and long-term observations of recognisable animals. Year-round, some 260 botos occurred in or near the 225-km2 Mamirauá várzea floodplain lake system, of which half were permanent residents by our definition. Seasonal variation in water levels influenced distribution between habitats but not the overall number of botos. Ninety percent of marked botos encountered within the lake system were permanent residents. There appeared to be a cline in site fidelity between those that always live in or near the system and those that visit at intervals of years. We estimated that 270 botos were "significant users" of the lake system (i.e., occurred within it for sufficient periods in a year to be observed at least once) and that many others visited for short periods. Individuals moved many tens to hundreds of kilometres along the rivers, but there was no broad-scale seasonal migration. The boto population of the central Amazon, at least, may be structured on the basis of floodplain lake systems, with extensive animal movement between systems. We estimate that 13 000 botos occur in the 11 240 km2 Mamirauá Sustainable Development Reserve, which covers an estimated 11%–18% of várzea habitat in Brazil.

scholarly journals 300 years of coastal salinization research in Germany – the Homann (1718) map of the Christmas Flood of 1717

2018 ◽  
Vol 54 ◽  
pp. 00011
Author(s):  
Georg J. Houben
Keyword(s):  
The Netherlands ◽  
Agricultural Land ◽  
High Tide ◽  
High Water ◽  
Water Levels ◽  
The North ◽  
The North Sea ◽  
The Mean ◽  
The Village ◽  
Two Sides

The Christmas Flood of 1717 was one of the most destructive storm floods in the North Sea region and affected large parts of the shores of Germany, the Netherlands and Germany (e.g. Jakubowski-Tiessen 1992). It occurred in the night from the 24th to the 25th of December 1717, when a strong northwesterly storm front pushed massive volumes of water into the funnel-shaped German Bight. Adding to the astronomical high tide occurring this night, water levels rose up to 4 m higher than the mean tidal high water mark. This lead to widespread overtopping and breaching of the dikes, which had been neglected in the preceding years due to extended periods of war and unrest. Since the event happened at night, the population was unable to react. About 9,000 people in Germany lost their lives and around 2,500 in the Netherlands. The small German town of Jever alone lost 1,700 people. In the village of Stollhamm, located on the peninsula of Butjadingen, which was exposed to the flood from two sides, 582 out of a population of 1,200 perished and only a third of the houses were not destroyed. In Eastern Frisia, 922 houses were completely destroyed and 1,672 damaged. In all of the affected regions in Germany, at least 3,000 houses were completely destroyed. Agriculture was severely affected by the salinization of large tracts of agricultural land and the loss of 2,300 horses, 9,500 cows, 2,800 sheep and 1,800 pigs was recorded in Eastern Frisia. In the following years, famines and epidemic plagues took a further toll on the population. Many people emigrated. It took several decades to reconstruct the dikes and to restore the livelihoods of the population.

scholarly journals Effects of hydrological regime and connectivity on the interannual variation in taxonomic similarity of periphytic algae

2009 ◽  
Vol 69 (2 suppl) ◽  
pp. 609-616 ◽  
Author(s):  
VM. Algarte ◽  
NS. Siqueira ◽  
EA. Murakami ◽  
L. Rodrigues
Keyword(s):  
Aquatic Macrophytes ◽  
Hydrological Regime ◽  
High Water ◽  
Flood Pulse ◽  
Paraná River ◽  
Water Levels ◽  
Periphytic Algae ◽  
Parana River ◽  
Eichhornia Azurea ◽  
Flood Pulses

The aim of this study was to analyze the effects of flood pulses (intensity) on the richness and composition of periphytic algae in lentic environments of the Upper Paraná River floodplain, over a six-year period. Other factors, such as connectivity of the environments with the main channel of the river and the availability of substrate for the periphyton, were also evaluated. For qualitative analyses, periphyton community was sampled from adult petioles of Eichhornia azurea Kunth taken from the littoral regions of the lakes studied. A total of 457 taxa of periphytic algae, distributed within 141 genera and 10 classes, were registered in the four environments. The greatest richness of periphytic algae was observed in connected floodplain lakes, especially in 2007 and during high water periods. In both connected and disconnected lakes, richness correlated positively with water levels of the Paraná River. Richness was also positively correlated with the number of taxa of aquatic macrophytes. The specific composition of periphytic algae differed between high and low water periods, and between connected and disconnected lakes. Therefore, among the considered variables, it is evident that flood pulse constitutes the principal force acting on periphytic algae communities of the floodplain, followed by the degree of connectivity and the presence of aquatic macrophytes.

scholarly journals Delineating the influence of water conditions and landscape on plant communities in eutrophic ditch networks

2021 ◽  
Author(s):  
André Mauchamp ◽  
Olivier Gore ◽  
Jean-Marc Paillisson ◽  
Benjamin Bergerot ◽  
Anne Bonis
Keyword(s):  
Species Richness ◽  
Plant Communities ◽  
Water Regime ◽  
High Water ◽  
Quality Parameters ◽  
Water Levels ◽  
Human Occupation ◽  
Landscape Characteristics ◽  
Management Actions ◽  
Influence Of Water

AbstractMarshlands and floodplains are generally characterized by a long history of human occupation and management, with strong impacts on biodiversity. In these landscapes, ditch networks often represent the last or most significant aquatic habitat, and significantly contribute to regional biodiversity. To determine the drivers of biodiversity in ditch networks, especially the importance of the water regime, we monitored vegetation in ditches in 11 sites (independent blocks of ditch networks) of an Atlantic marshland (the Marais poitevin, France) over a 4-year period, and a panel of local environmental conditions and landscape characteristics. Large differences in the species richness and composition of ditch plant communities were observed among sites. The water regime had a predominant effect on all descriptors of ditch plant communities. High water levels combined with strong temporal variability, including drying-out periods, were found associated to the communities with the highest species richness. By contrast, water quality parameters did not influence plant communities across sites. Among landscape variables, woodland cover combined with high hedge cover along the ditches significantly influenced plant composition and species richness. These results are discussed in terms of management actions that may promote the diversity and composition of ditch plant communities and address conservation challenges.

scholarly journals Hydrological evidence and causes of seasonal low water levels in a large river-lake system: Poyang Lake, China

2016 ◽  
Vol 47 (S1) ◽  
pp. 24-39 ◽  
Author(s):  
Jing Yao ◽  
Qi Zhang ◽  
Yunliang Li ◽  
Mengfan Li
Keyword(s):  
Yangtze River ◽  
Water Resource Management ◽  
Poyang Lake ◽  
Large River ◽  
Water Levels ◽  
The Yangtze River ◽  
Lake System ◽  
Spatial Differences ◽  
Northern Portion ◽  
Lake Systems

Seasonal variations in local catchments and connected rivers lead to complex hydrological behaviours in river-lake systems. Poyang Lake is a seasonally dynamic lake with frequent low levels in spring and autumn, which may be triggered by the local catchment and Yangtze River. Based on two typical years, a hydrodynamic model combined with long term hydrological observations was applied to quantify the spatiotemporal impacts of the local catchment and Yangtze River on spring and autumn low water levels in Poyang Lake. As a first attempt, this study explored the spatial differences of the two influences. Simulation results showed that the contributions of the catchment and the Yangtze River were approximately 70% and 30% in spring 1963, and 5% and 95% in autumn 2006, respectively. The area of catchment influence was mainly distributed in channels and southern floodplains, with relatively uniform water levels. The area impacted by the Yangtze River mainly spanned from the northern portion of the waterway to the central lake, with strong spatial variability. This study focused on two typical years; however, the results can be extended to explain common hydrological phenomena and improve future strategies of water resource management in this river-lake system.

Das waldreiche obere Theresiental (Transkarpatien, Ukraine) – geografisch-ökologische und sozioökonomische Beschreibung | The forest-rich upper Theresian Valley (Transcarpathia, Ukraine): a geographic-ecological and socio-economical description

2007 ◽  
Vol 158 (1-2) ◽  
pp. 14-21
Author(s):  
Vasyl Sabadosh ◽  
Oleg Suprunenko
Keyword(s):  
Forest Management ◽  
High Water ◽  
The State ◽  
Water Levels ◽  
Private Companies ◽  
Foreign Investors ◽  
Wood Processing ◽  
Job Opportunities ◽  
Orange Revolution

The upper Theresian Valley lies along the southwest-facing ridge of the Ukrainian Carpathians. Despite expansive forestation high water levels are frequent. The forest belongs to the state and is centrally administrated. Felling is sometimes outsourced to private companies and private companies have also been founded to process the timber. Job opportunities have become fewer and illegal work is increasing. A new democratic awareness has emerged since the «Orange Revolution» in 2004. With foreign investors, however, new risks emerge. The authors recommend giving monies from forest management to the communities, the founding of new wood processing enterprises and more transparent information.

Lake and inland dunes as interconnected Systems: The story of Lake Tresssee and an adjacent dune field (Schleswig-Holstein, North Germany)

The Holocene ◽  
2020 ◽  
pp. 095968362098168
Author(s):  
Christian Stolz ◽  
Magdalena Suchora ◽  
Irena A Pidek ◽  
Alexander Fülling
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Environmental Changes ◽  
High Water ◽  
Alluvial Fan ◽  
Water Levels ◽  
Lake Area ◽  
Dune Field ◽  
The North ◽  
Sand Drift

The specific aim of the study was to investigate how four adjacent geomorphological systems – a lake, a dune field, a small alluvial fan and a slope system – responded to the same impacts. Lake Tresssee is a shallow lake in the North of Germany (Schleswig-Holstein). During the Holocene, the lake’s water surface declined drastically, predominately as a consequence of human impact. The adjacent inland dune field shows several traces of former sand drift events. Using 30 new radiocarbon ages and the results of 16 OSL samples, this study aims to create a new timeline tracing the interaction between lake and dunes, as well, as how both the lake and the dunes reacted to environmental changes. The water level of the lake is presumed to have peaked during the period before the Younger Dryas (YD; start at 10.73 ka BC). After the Boreal period (OSL age 8050 ± 690 BC) the level must have undergone fluctuations triggered by climatic events and the first human influences. The last demonstrable high water level was during the Late Bronze Age (1003–844 cal. BC). The first to the 9th century AD saw slightly shrinking water levels, and more significant ones thereafter. In the 19th century, the lake area was artificially reduced to a minimum by the human population. In the dunes, a total of seven different phases of sand drift were demonstrated for the last 13,000 years. It is one of the most precisely dated inland-dune chronologies of Central Europe. The small alluvial fan took shape mainly between the 13th and 17th centuries AD. After 1700 cal. BC (Middle Bronze Age), and again during the sixth and seventh centuries AD, we find enhanced slope activity with the formation of Holocene colluvia.

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