scholarly journals Restoring dissolved organic carbon subsidies from floodplains to lowland river food webs: a role for environmental flows?

2016 ◽  
Vol 67 (9) ◽  
pp. 1387 ◽  
Author(s):  
Darren S. Baldwin ◽  
Matthew J. Colloff ◽  
Simon M. Mitrovic ◽  
Nick R. Bond ◽  
Ben Wolfenden
Keyword(s):  
Food Webs ◽  
Environmental Flows ◽  
Ecological Condition ◽  
Lowland River ◽  
River Channels ◽  
Apparent Lack ◽  
River Floodplain ◽  
Main River ◽  
Main River Channel ◽  
Terrestrial Subsidies

Environmental flows are managed events in river systems designed to enhance the ecological condition of aquatic ecosystems. Although not traditionally seen as important in lowland rivers, there is mounting evidence that terrestrial subsidies can be an important energy source in aquatic metazoan food webs. We argue that the apparent lack of importance of terrestrial subsidies to many lowland river food webs may reflect an artefact resulting from historical anthropogenic changes to lowland river–floodplain ecosystems, including the loss of lateral connectivity between rivers and their floodplains, changes in floodplain land use and carbon stores, and loss of sites of transformation within the main channel. The loss of floodplain subsidies to the main river channel can be partially redressed using environmental flows; however, this will require mimicking important aspects of natural high-flow events that have hitherto been overlooked when targeting environmental flows to a limited suite of biota. We suggest that key biotic targets for environmental flow releases may not be achievable unless river–floodplain subsidies are sufficiently restored. Environmental flows can go some way to addressing this shortfall, but only if floodplain subsidies to river channels are explicitly included in the design and management of environmental flows.

Structural variability and invasions of pioneer plant communities in riparian habitats of the middle Adour River (SW France)

1995 ◽  
Vol 73 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Eric Tabacchi
Keyword(s):  
Exotic Species ◽  
Life Forms ◽  
River Channels ◽  
Main River ◽  
Main River Channel ◽  
Pioneer Plant ◽  
Littoral Zones ◽  
History Of ◽  
Number Of Individuals ◽  
Sw France

The pioneer vegetation of five distinct littoral zones along the middle Adour River (SW France) was investigated during three successive low water periods. There was a high year to year variability in the hydrology of the river during the period of study with a normal (1987), a wet (1988), and a dry year (1989). Changes in population and life forms density of both native and exotic species were analyzed. Communities were species rich when 45% of the 428 species present in the study area (2-km-long stretch) were found in the 10 × 10 m plots. Most of the species were annuals, but perennials were also abundant. The exotic component represented nearly 20% of the species and of the total number of individuals. There was high spatial variability in pioneer communities; sites of the main river channel differed from those along abandoned arms in species composition and population densities. The communities responded to changes in the hydrology of the preceding growing season. Sharp year to year differences were found in population and species density. The nature of the hydrological change drove those changes. Plots located in the oldest arms of the river showed a greater sensitivity to flooding conditions than those located in young littoral zones, with an increase in hygrophilous species. Alternatively, plots adjacent to active river channels showed greater sensitivity to drought conditions, as the density of short-lived and exotic species increased. Comparatively, exotics appeared to be more sensitive to the type of hydrological changes than natives. Warmer years also affected native plants, which reacted like invasive species. Relationships between the observed changes, the level of hydrological disturbance, and the recent history of each site are discussed in this paper with the possibility of using introduced species as descriptors of climatic and hydrologic changes. Key words: riparian vegetation, pioneer community, community structure, biological invasions, hydrological perturbation, variability.

scholarly journals Crevasse splays within a lignite seam at the Tomisławice opencast mine near Konin, central Poland: architecture, sedimentology and depositional model

Geologos ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 25-37 ◽  
Author(s):  
Lilianna Chomiak
Keyword(s):  
Middle Miocene ◽  
Structural Features ◽  
Fine Grained ◽  
Opencast Mine ◽  
Main River ◽  
Main River Channel ◽  
Lignite Mine ◽  
Flooding Event ◽  
Crevasse Splay ◽  
Sandy Sediments

AbstractThe present article focuses predominantly on sandy deposits that occur within the Middle Miocene lignite seam at the Tomisławice opencast mine, owned by the Konin Lignite Mine. As a result of mining activity, these siliciclastics were available for direct observation in 2015–2016. They are situated between two lignite benches over a distance of ~500 m in the lower part and ~200 m in the higher part of the exploitation levels. The maximum thickness of these sandy sediments, of a lenticular structure in a S–N cross section, is up to 1.8 m. With the exception of a thin lignite intercalation, these siliciclastics comprise mainly by fine-grained and well-sorted sands, and only their basal and top layers are enriched with silt particles and organic matter. Based on a detailed analysis of the sediments studied (i.e., their architecture and textural-structural features), I present a discussion of their genesis and then propose a model of their formation. These siliciclastics most likely formed during at least two flood events in the overbank area of a Middle Miocene meandering or anastomosing river. Following breaching of the natural river levee, the sandy particles (derived mainly from the main river channel and levees) were deposited on the mire (backswamp) surface in the form of crevasse splays. After each flooding event, vegetation developed on the top of these siliciclastics; hence, two crevasse-splay bodies (here referred to as the older and younger) came into existence. As a result, the first Mid-Polish lignite seam at the Tomisławice opencast mine is currently divided in two by relatively thick siliciclastics, which prevents a significant portion of this seam from being used for industrial purposes.

scholarly journals Habitat factors differentiating the occurrence of Ostracoda (Crustacea) in the floodplain of a small lowland River Krąpiel (N-W Poland)

2020 ◽  
pp. 23
Author(s):  
Agnieszka Szlauer-Łukaszewska ◽  
Vladimir Pešić
Keyword(s):  
Abiotic Factors ◽  
River Channel ◽  
Water Bodies ◽  
Oxbow Lakes ◽  
Factors Associated ◽  
Main River ◽  
Main River Channel ◽  
Habitat Factors ◽  
Sediment Sorting ◽  
Physical And Chemical

We analysed the occurrence of ostracods in a small river, taking into account all the types of water bodies in the floodplain − these included helocrenes, oxbow lakes, and ponds, as well as the main river channel. The objective of the study was to investigate the variation in ostracod communities and identify those factors determining species distribution. The environmental factors considered were the type of water body, responsible for 17% of the variance, the physical and chemical water properties (29%), and the biotic and abiotic factors associated with the substrate type (23%). Among the factors associated with the substrate, sediment sorting, plant coverage and insolation were the most important. The ostracod fauna of the helocrenes differed from that of the other water bodies in the floodplain. In the water bodies of the Krąpiel valley and in the main river channel, 33 ostracod species were recorded, of which 26 were found in the main river channel. Refugia in the floodplain were the main source of the diversity and abundance of ostracods in the main river channel. The mean density in the main river channel was very low, at 330 indiv. m−2, while in the water bodies of the floodplain it was the greatest, reaching up to 5568 indiv. m−2.

scholarly journals Coleoptera associated with macrophytes of the genus Salvinia in four oxbow lakes in two river basins in southeast Brazil

2015 ◽  
Vol 75 (4 suppl 1) ◽  
pp. 108-118 ◽  
Author(s):  
M. C. Paula-Bueno ◽  
A. A. Fonseca-Gessner
Keyword(s):  
River Basins ◽  
River Channel ◽  
The State ◽  
The Other ◽  
Oxbow Lakes ◽  
Aquatic Fauna ◽  
Southeast Brazil ◽  
Main River ◽  
Main River Channel ◽  
The Difference

Abstract Macrophytes in oxbow lakes represent an important substrate for the Coleoptera. Two oxbow lakes the Rio Paranapanema were studied and the other two Rio Mogi-Guaçu, in the State de São Paulo, Brasil. In this study, there is greater similarity between the communities of Coleoptera of lakes greater connectivity with the main river channel or the difference in the species of Salvinia collected in the lakes studied interferes Coleoptera fauna that uses as substrate. A total of 9,222 specimens of Coleoptera were collected and identified in 10 families and 40 genera. The analysis MDS for abundance of Coleoptera showed the grouping of the oxbow lakes the Paranapanema River and a distancing the oxbow lakes the Mogi-Guaçu. The PERMANOVA test did not reveal any difference in the fauna between the wet and dry periods. It was concluded that the connectivity between river and lake is not decisive for the richness and abundance of aquatic fauna of Coleoptera. Therefore, the richness and abundance of aquatic Coleoptera associated vary with the species of Salvinia used as substrate.

scholarly journals Impacts of hydrological restoration on lowland river floodplain plant communities

2020 ◽  
Vol 28 (3) ◽  
pp. 403-417
Author(s):  
Daniel R. Richards ◽  
Helen L. Moggridge ◽  
Philip H. Warren ◽  
Lorraine Maltby
Keyword(s):  
Plant Communities ◽  
Lowland River ◽  
River Floodplain

High prevalence of non-native fish species in a remote region of the Mamberamo River, Indonesia

2020 ◽  
Vol 26 (3) ◽  
pp. 293
Author(s):  
Arif Wibowo ◽  
Dwi Atminarso ◽  
Lee Baumgartner ◽  
Anti Vasemagi
Keyword(s):  
Native Species ◽  
River System ◽  
New Guinea ◽  
Current Status ◽  
Native Fish ◽  
Fish Diversity ◽  
Main River ◽  
Main River Channel ◽  
High Prevalence ◽  
Major River

Indonesian freshwater fish diversity is threatened by human activities such as logging, land clearing, pollution and introduction of non-native species. The latter may pose serious threats to endemic freshwater fauna even in relatively pristine and isolated habitats. One such area, West Papua in the island of New Guinea, is one of the least studied regions in the world and a biodiversity hotspot. The Mamberamo River contains the highest proportion of non-native fish compared to other major river systems in New Guinea. To document this, we conducted a field study to validate and further temporally characterise the fish biodiversity to ascertain its current status. Since the last ichthyological survey 15 years ago, we detected two additional non-native species (Leptobarbus melanopterus and Oreochromis niloticus) that have established in the river system. Moreover, our survey revealed that non-native fish are extremely common in the mid reaches of the Mamberamo River, comprising 74% of total catch, with non-native Barbonymus gonionotus (family Cyprinidae) now established as the dominant species. The biomass of non-native B. gonionotus now exceeds that of all native fish combined in the main river channel. These results highlight the serious threat of invasive species in remote regions that support high levels of endemic biodiversity. Plans for containment, prevention through education programmes, and management are urgently required.

scholarly journals Quantitative fidelity of recent freshwater mollusk assemblages from the Touro Passo River, Rio Grande do Sul, Brazil

2006 ◽  
Vol 96 (4) ◽  
pp. 453-465 ◽  
Author(s):  
Alcemar R. Martello ◽  
Carla B. Kotzian ◽  
Marcello G. Simões
Keyword(s):  
Dominant Species ◽  
Rank Order ◽  
Rio Grande ◽  
Taxonomic Composition ◽  
Small Scale ◽  
Rio Grande Do Sul ◽  
Main River ◽  
Main River Channel ◽  
Structure Of Communities ◽  
Uruguay River

This study represents one of the first contributions to the knowledge on the quantitative fidelity of the recent freshwater molluscan assemblages in subtropical rivers. Thanatocoenoses and biocoenoses were studied in straight and meandering to braided sectors, in the middle course of the Touro Passo River, a fourth-order tributary of the Uruguay River, located in the westernmost part of the State of Rio Grande do Sul. Samplings were carried out through quadrats of 5 m², five in each sector. A total area of 50 m² was sampled. Samplings were also made in a lentic environment (abandoned meander), with intermittent communication with the Touro Passo River, aiming to record out-of-habitat shell transportation from the lentic communities to the main river channel. The results show that, despite the frequent oscillation of the water level, the biocoenosis of the Touro Passo River shows high ecological fidelity and undergoes little influence from the lentic vicinal environments. The taxonomic composition and some features of the structure of communities, especially the dominant species, also reflect some ecological differences between the two main sectors sampled, such as the complexity of habitats in the meandering-sector. Regarding the quantitative fidelity, 60% of the species found alive were also found dead and 47.3% of the species found dead were also found alive, at river-scale. However, 72% of the dead individuals belong to species also found alive. This value might be related with the good rank order correlation obtained for live/dead assemblages. Consequently, the dominant species of the thanatocoenoses could be used to infer the ecological attributes of the biocoenoses. The values of all the indexes analyzed were very variable in small-scale samplings (quadrat), but were more similar to others registered in previous studies, when they were analyzed in a station and river scale.

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