Spatial distribution of littoral invertebrates in the lower Murray - Darling River system, Australia

1998 ◽  
Vol 49 (2) ◽  
pp. 171 ◽  
Author(s):  
Fran Sheldon ◽  
Keith F. Walker
Keyword(s):  
Spatial Distribution ◽  
River System ◽  
Littoral Invertebrates ◽  
Paratya Australiensis

The abundance and richness of macroinvertebrates in the lower Murray and Darling rivers were examined at a macroscale (rivers), mesoscale (billabongs, backwaters, channel) and microscale (vegetation, snags, substrata). In the Darling, insects dominated (85% of taxa, 81% of individuals); the richest taxa were Diptera (26 taxa) and Coleoptera (15 taxa) and the most abundant were Hemiptera (47%) and Diptera (35%). In the Murray, insects again dominated (84% of taxa, 52% of individuals), particularly Diptera (22 taxa), Coleoptera (12 taxa) and Hemiptera (9 taxa), but there were more crustaceans (9% of taxa, 47% of individuals, particularly the atyid shrimp Paratya australiensis). Both assemblages were uneven: in the Darling, >50% of biomass was Micronecta spp. (Corixidae), Dicrotendipes sp. (Chironomidae) and Macrobrachium australiense (Palaemonidae); in the Murray, 70% of biomass was P. australiensis and Caridina mccullochi (Atyidae) and the insects Micronecta spp. (Corixidae) and Chironomus sp. (Chironomidae). Abundances generally were greatest in the Murray. Hydrologic and geomorphic factors influenced assemblages at the macroscale, whereas microhabitat diversity dominated at the mesoscale.

Population dynamics and spatial distribution of monogeneans on the gills of Oreochromis mossambicus (Peters, 1852) from two lakes of the Limpopo River System, South Africa

2010 ◽  
Vol 85 (2) ◽  
pp. 146-152 ◽  
Author(s):  
G.N. Madanire-Moyo ◽  
M.M. Matla ◽  
P.A.S. Olivier ◽  
W.J. Luus-Powell
Keyword(s):  
Spatial Distribution ◽  
Dominant Species ◽  
Parasite Species ◽  
Parasitic Infection ◽  
River System ◽  
Oreochromis Mossambicus ◽  
Seasonal Fluctuations ◽  
Parasite Abundance ◽  
Gill Parasite ◽  
The Mean

AbstractAn investigation was conducted into the parasitic infection of an indigenous cichlid, Oreochromis mossambicus, collected seasonally from the Nwanedi-Luphephe dams of the Limpopo River System from July 2007 to April 2009. Of 157 host specimens examined, 115 (73.25%) were infected by at least one gill parasite. In all, 1565 monogenean specimens were collected, belonging to five different species and two genera: Cichlidogyrus (C. halli, C. sclerosus, C. tilapiae and C. dossoui) and Scutogyrus (S. longicornis). Infracommunities were poor, with only 27 (17.20%) hosts harbouring four of the five species observed. Cichlidogyrus halli was the dominant species, with a prevalence of 73.25%. Prevalence values for each of the other four species were less than 50%. The mean intensities for each of the five species were low ( < 8 parasites/host). The parasite abundance and intensity levels were not influenced by either the sex or the size of the host. The abundance of all parasite species except for S. longicornis exhibited seasonal fluctuations, reaching peaks in winter and summer. The spatial distribution of each parasite was studied on different regions of the gill, and positive associations among some species were revealed.

scholarly journals The River Systems in Small Catchments in the Context of the Horton’s and Schumm’s Laws – Implication for Hydrological Modelling. The Case Study of the Polish Carpathians

2015 ◽  
Vol 34 (1) ◽  
pp. 85-98 ◽  
Author(s):  
Tomasz Bryndal
Keyword(s):  
Spatial Distribution ◽  
System Development ◽  
River System ◽  
Hydrological Models ◽  
Ungauged Catchments ◽  
Stream Length ◽  
Small Catchment ◽  
Catchment Areas ◽  
The Mean ◽  
The Law

Abstract In ungauged catchments, flood hydrographs are usually simulated/reconstructed by simple rainfall-runoff and routing models. Horton’s and Schumm’s ratios serve as the input data for many of these models. In this paper, more than 800 Carpathian catchments (up to 35.2 km2 in area) were investigated in context of the “Horton’s and Schumm’s laws”. Results reveal that the “law of stream number” and “law of stream areas” are fulfilled in almost all catchments. The mean that values of the bifurcation ratio (RB) and the area ratio (RA) reach 3.8 and 4.8, respectively, and are thus comparable to values reported in other regions of the world. However, the “law of stream lengths” is not fulfilled in more than half of the catchments, which is not consistent with many theoretical studies reported in the literature. Only 383 (48%) catchments fulfill the “law of stream length”, with the mean value of the length ratio (RL)=2.3. There was no relationship found between the geological/geomorphological settings that influence river system development and the spatial distribution of catchments where the “law of stream length” was or was not was fulfilled. A similar conclusion was reached for the spatial distribution of the RB, RL, and RA ratios. These results confirmed that the use of Horton’s and Schumm’s ratios for the evaluation of the influence of geological/geomorphological settings on the river system development is limited. Among the lumped hydrological models, those requiring the RB, RL, and RA ratios have been extensively studied over last decades. This study suggests that the application of these models may be limited in small catchment areas; therefore, more attention should be placed on the development of hydrological models where the RB, RL, and RA ratios are not necessary.

Spatial distribution of copper content in sediments of the Yangtze River system

1997 ◽  
Vol 42 (15) ◽  
pp. 1294-1297
Author(s):  
Chaosheng Zhang ◽  
Shen Zhang ◽  
Jianbang He
Keyword(s):  
Spatial Distribution ◽  
Copper Content ◽  
Yangtze River ◽  
River System ◽  
The Yangtze River
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