Structure of benthic macroinvertebrates and dynamics in the northern lagoon of Tunis

2009 ◽  
Vol 89 (7) ◽  
pp. 1305-1318 ◽  
Author(s):  
S. Tlig-Zouari ◽  
T. Mami ◽  
F. Maamouri
Keyword(s):  
Benthic Macroinvertebrates ◽  
Benthic Community ◽  
Benthic Communities ◽  
Remarkable Change ◽  
Abiotic Parameters ◽  
Gulf Of Tunis ◽  
Physico Chemical ◽  
Marine Influence ◽  
The One ◽  
As Effects

Sampling data on abiotic parameters and benthic communities in the northern lagoon of Tunis were obtained seasonally from November 1999 to November 2000. Abiotic parameters studied revealed evident improvement of water quality compared with previous. Indeed, management has re-established a tidal marine influence (Gulf of Tunis), induced a remarkable change in physico-chemical parameters and as a consequence, a regulation of the lagoon environmental quality. A total of 90 species of benthic macroinvertebrates, belonging to seven different taxa were collected in the northern lagoon of Tunis. A comparison of ecological indices indicate significant variations in the spatial and seasonal distribution and structure of the benthic community and reflect changes that might be related to open marine water and climatic influences as well as effects of discharge of the neighbouring city. Generally, the lagoon macrobenthic community appeared to be better structured, richer and more diverse than the one described before sanitation works began. However, significant disturbance of the benthic communities is detected in the south-eastern lagoon zone (C) and is dominated by disturbance indicator species. In contrast, the Station A2 which is sufficiently influenced by marine currents, is dominated by species of marine affinity and indicates an undisturbed zone. Multivariate analysis indicates heterogeneity in the benthic community structure between stations and suggests that the most significant variations of abundance occur in the groups: Anthozoa, Placophora, Cephalopoda, Ascidia and Echinodermata. The results of correspondence analysis also testify to a gradational distribution of benthic species in relation to hydrological and edaphic (organic matter) factors.

scholarly journals Assessment of the Impact of Small Hydropower Plants on the Ecological Status Indicators of Water Bodies: A Case Study in Lithuania

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 433
Author(s):  
Laima Česonienė ◽  
Midona Dapkienė ◽  
Petras Punys
Keyword(s):  
Water Quality ◽  
Benthic Macroinvertebrates ◽  
Suspended Solids ◽  
Ecological Status ◽  
Fish Abundance ◽  
Water Bodies ◽  
Small Hydropower ◽  
Hydropower Plants ◽  
Physico Chemical ◽  
The Impact

Hydropower plants produce renewable and sustainable energy but affect the river’s physico-chemical characteristics and change the abundance and composition of the aquatic organisms. The impact of large HPPs on the ecological conditions of surface water bodies have been extensively studied, but less attention has been paid to environmental impact studies of small hydropower plants (SHPs). The impact of hydropeaking on both the river flow regime and ecosystems has been well-studied for peaking mode plants, mainly medium to large-sized ones. However, for small hydroelectric power plants, and especially for those in lowland rivers, the available information on water quality, benthic macroinvertebrates communities and fish abundance, and biomass is not sufficient. Ten small hydropower plants were selected, and the ecological status of water bodies was assessed in different parts of Lithuania. The studies were performed at the riverbed upstream from the SHPs, where the hydrological regime has not changed, and downstream from the SHPs. It was found that the small hydropower plants do not affect the physico-chemical values of the water quality indicators. This study demonstrated that the total number of benthic macroinvertebrates taxa (TS) is influenced by the concentration of nitrogen and suspended solids, the water flow, the river area, and the current speed; the number of EPT (Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies)) taxa is influenced by the concentration of nitrogen and suspended solids. The studied indicators do not have a significant impact on biomass. The SHPs affect the fish abundance and biomass. The Lithuanian fish index (LFI) is influenced by the average depth and area of the river. Some SHPs operating in lowland areas may yield somewhat significant hydrograph ramping but more detailed investigation is needed to support the significance of this impact on the biological indices.

scholarly journals Colonization by benthic macroinvertebrates in two artificial substrate types of a Riparian Forest

2016 ◽  
Vol 28 (0) ◽  
Author(s):  
Lívia Borges dos Santos ◽  
Cyntia Goulart Côrrea Bruno ◽  
Jean Carlos Santos
Keyword(s):  
Benthic Macroinvertebrates ◽  
Benthic Community ◽  
Riparian Forest ◽  
Organic Substrate ◽  
Ecological Succession ◽  
Artificial Substrates ◽  
Significant Difference ◽  
Inorganic Substrates ◽  
Dry Seasons ◽  
Inorganic Substrate

Abstract: Aim To analyze the efficiency of organic and inorganic substrates in samples of benthic macroinvertebrates of riparian forests from the Cerrado. Specific objectives (i) characterize the ecological succession and taxonomic richness of benthic macroinvertebrates in stream affluent of a riparian forest; (ii) analyze the influence of seasonality on the colonization of macroinvertebrates; and (iii) determine the effect of the types of artificial substrates on the richness, composition and abundance of the benthic community. Methods Sampling was carried out in the rainy and dry seasons, and we installed in the watercourse two types of substrates: organic (leaf packs) and inorganic (bricks), organized in pairs. Six samples per season were done to verify colonization, succession, richness and abundance of benthic community. The substrates were carefully sorted and the organisms were identified to the lowest possible taxonomic level. Results The ecological succession was clearly observed, with the initial occurrence of Chironomidae and Baetidae (considered early colonizers), and a late occurrence of organisms such as Helotrephidae and Trichoptera (considered late colonizers). No significant difference was found in the richness and abundance among the studied seasons (rainy and dry), but the organic substrate was significantly higher than the inorganic substrate for these parameters. Conclusion Organic artificial substrates are more efficient in characterizing the community of benthic macroinvertebrates in the study area, because they are more similar to the conditions of the substrate found naturally in the environment.

scholarly journals Tolerance of benthic macroinvertebrates to organic enrichment in highland streams of northeastern Rio Grande do Sul, Brazil

2014 ◽  
Vol 26 (2) ◽  
pp. 119-128 ◽  
Author(s):  
Aline Correa Mazzoni ◽  
Rosane Lanzer ◽  
Alois Schafer
Keyword(s):  
Cluster Analysis ◽  
Benthic Macroinvertebrates ◽  
Benthic Communities ◽  
Rio Grande ◽  
Interquartile Range ◽  
Organic Enrichment ◽  
Rio Grande Do Sul ◽  
Pollution Levels ◽  
Chemical Index ◽  
And Cluster Analysis

AIM: the aim of this study was to determine the ecological valence of benthic macroinvertebrates at different pollution levels in highland rivers and streams of Rio Grande do Sul; METHODS: the dataset proceeds from samplings performed between 2002-2011 in 35 lotic ecosystems. The Chemical Index was used to determine pollution levels. Indices of richness and Shannon diversity were applied to characterize the structure of benthic communities. The descriptors used to determine taxa's ecological valence were selected according to Coefficient of Variation and regression analyses. Groups of tolerance were identified using Interquartile range and cluster analysis; RESULTS: Conductivity and Chemical Index were the descriptors best related with diversity of benthic macroinvertebrate community. These metrics were used to determine the tolerance range of 38 taxa. Interquartile range and cluster analysis revealed three groups of taxa, according to their occurrence in different levels of pollution: taxa with narrow amplitudes, present at sites with very low or very high load of organic enrichment; taxa with moderate amplitude, found until moderately polluted sites; and taxa with occurrence in widespread environmental conditions. The results, when compared to other studies in Brazil, showed differences in some taxa's tolerance. This observation indicates the need to assess the bioindication potential of these taxa in genus and species level; CONCLUSION: the present study contributes to increase knowledge about the bioindicator potential of benthic macroinvertebrates. Therefore, the study supports an advanced biomonitoring of ecological quality in mountain streams of southern Brazil.

scholarly journals MRI Relaxivity Changes of the Magnetic Nanoparticles Induced by Different Amino Acid Coatings

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 394 ◽  
Author(s):  
Iryna Antal ◽  
Oliver Strbak ◽  
Iryna Khmara ◽  
Martina Koneracka ◽  
Martina Kubovcikova ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Chemical Properties ◽  
Hydrodynamic Diameter ◽  
Contrast Imaging ◽  
Dispersed Particles ◽  
Physico Chemical ◽  
The One ◽  
Molecular Contrast ◽  
The Impact ◽  
Positively Charged

In this study, we analysed the physico-chemical properties of positively charged magnetic fluids consisting of magnetic nanoparticles (MNPs) functionalised by different amino acids (AAs): glycine (Gly), lysine (Lys) and tryptophan (Trp), and the influence of AA–MNP complexes on the MRI relaxivity. We found that the AA coating affects the size of dispersed particles and isoelectric point, as well as the zeta potential of AA–MNPs differently, depending on the AA selected. Moreover, we showed that a change in hydrodynamic diameter results in a change to the relaxivity of AA–MNP complexes. On the one hand, we observed a decrease in the relaxivity values, r1 and r2, with an increase in hydrodynamic diameter (the relaxivity of r1 and r2 were comparable with commercially available contrast agents); on the other hand, we observed an increase in r2* value with an increase in hydrodynamic size. These findings provide an interesting preliminary look at the impact of AA coating on the relaxivity properties of AA–MNP complexes, with a specific application in molecular contrast imaging originating from magnetic nanoparticles and magnetic resonance techniques.

scholarly journals Development of mango (Mangifera indica L.) energy drinks

2017 ◽  
Vol 70 (1) ◽  
pp. 8115-8121
Author(s):  
Carlos Julio Márquez Cardozo ◽  
Carlos Andrés Jiménez Castañeda ◽  
Carolina Sofía Salazar Ripoll
Keyword(s):  
Confidence Level ◽  
Carboxymethyl Cellulose ◽  
High Density Polyethylene ◽  
Mangifera Indica ◽  
Storage Period ◽  
Soluble Solids ◽  
Browning Index ◽  
Physico Chemical ◽  
Off Flavors ◽  
The One

The effect of two hydrocolloids, pectin and carboxymethyl cellulose (CMC), was evaluated in mango beverage stability (Mangifera indica L.) formulated and developed with caffeine at a concentration of 30 mg/100 mL. The physico-chemical and sensory characteristics of color, acidity, viscosity, total soluble solids, pH, flavor, aroma and texture were studied every three days over a 12-day period. The beverages were packaged in high-density polyethylene containers with a 250 mL capacity and were stored at 5 °C and 90% RH for the duration of the experimentation period. The drinks with added pectin showed greater stability and lower acidity values than the control, but higher values than those prepared with CMC. The drinks made with CMC had a significantly higher viscosity at a 95% confidence level than those made with pectin or the control beverages. The treatment that showed the lowest browning index was the one added with pectin. Concerning the sensory evaluation, the drinks showed significant differences at a 95% confidence level; the drink made with pectin was the most widely accepted. It was concluded that the most stable drinks were those made with pectin because they presented the lowest height in millimeters of precipitate solids over the storage period. No off-flavors in beverages were perceived by the judges.

scholarly journals Depth moderates loss of marine foundation species after an extreme marine heatwave: could deep temperate reefs act as a refuge?

2020 ◽  
Vol 287 (1928) ◽  
pp. 20200709
Author(s):  
Ana Giraldo-Ospina ◽  
Gary A. Kendrick ◽  
Renae K. Hovey
Keyword(s):  
Transition Zone ◽  
Community Composition ◽  
Benthic Community ◽  
Benthic Communities ◽  
Foundation Species ◽  
Temperate Reefs ◽  
Environmental Extremes ◽  
Deep Reefs ◽  
Clear Shift ◽  
Western Australian

Marine heatwaves (MHWs) have been documented around the world, causing widespread mortality of numerous benthic species on shallow reefs (less than 15 m depth). Deeper habitats are hypothesized to be a potential refuge from environmental extremes, though we have little understanding of the response of deeper benthic communities to MHWs. Here, we show how increasing depth moderates the response of seaweed- and coral-dominated benthic communities to an extreme MHW across a subtropical–temperate biogeographical transition zone. Benthic community composition and key habitat-building species were characterized across three depths (15, 25 and 40 m) before and several times after the 2011 Western Australian MHW to assess resistance during and recovery after the heatwave. We found high natural variability in benthic community composition along the biogeographic transition zone and across depths with a clear shift in the composition after the MHW in shallow (15 m) sites but a lot less in deeper communities (40 m). Most importantly, key habitat-building seaweeds such as Ecklonia radiata and Syctothalia dorycarpa which had catastrophic losses on shallow reefs, remained and were less affected in deeper communities. Evidently, deep reefs have the potential to act as a refuge during MHWs for the foundation species of shallow reefs in this region.

Rock revolution or time-no-changes: visions of change and continuity in rock music

Popular Music ◽  
1985 ◽  
Vol 5 ◽  
pp. 97-121 ◽  
Author(s):  
Alan Durant
Keyword(s):  
Popular Music ◽  
Rock Music ◽  
Musical Style ◽  
Remarkable Change ◽  
The One ◽  
Underlying Processes

Discussions of rock or contemporary popular music are very often suffused with suggestions of massive and remarkable ‘change’ (in musical style, in surrounding fashions, etc.). Just as often, however, they are filled with virtually opposite visions of endless repetition, or continual ‘sameness’ (the music all merely sounding alike). Diverging in this way, views of change in popular music tend towards extreme polarisation – so much evidently depending upon the scale and scope of comparison, and indeed much of the problem centring on the domain or level in music isolated as the one most likely to offer explanation of the underlying processes.

Is freshwater quality adequately defined by physico-chemical components? Results from two drought-affected estuaries on the east coast of South Africa

2001 ◽  
Vol 52 (3) ◽  
pp. 267 ◽  
Author(s):  
C. F. Mackay ◽  
D. P. Cyrus
Keyword(s):  
Water Quality ◽  
East Coast ◽  
Chemical Properties ◽  
Benthic Fauna ◽  
Chemical Components ◽  
Physico Chemical ◽  
Marine Influence ◽  
Chemical Conditions ◽  
Biological Component ◽  
Two Populations

From 1992 to 1994 the physico-chemical conditions of two systems on the east coast of southern Africa shifted from estuarine to freshwater as a result of mouth closure during the prevailing drought. Although there was gradual colonization by freshwater benthic invertebrates, both systems were dominated by estuarine benthic infauna. The upper reaches of the Siyaya Estuary were entirely characterized by freshwater taxa (95%) by 1994, whereas Nhlabane Estuary showed a smaller increase in the number of these fauna. Non-metric multidimensional scaling plotted benthic populations as separate groups each year. These groups were not the result of a gradual shift in benthic fauna from an estuarine towards a freshwater bias. Rather, the upper estuarine reaches were dominated by taxa characteristic of freshwater environments, despite similar water quality conditions along all reaches. Three quarters of the zoobenthic communities (expressed as density m–2) were still estuarine in nature. The two populations were comparable to those occurring in nearby freshwater coastal lakes, which have been subject to marine influence in geological history. It was concluded that assessment of the biological component in addition to the physico-chemical properties should be considered when defining water quality in such systems.

scholarly journals Effects of scallop dredging on macrobenthic communities in west Iceland

2006 ◽  
Vol 63 (3) ◽  
pp. 434-443 ◽  
Author(s):  
Elena Guijarro Garcia ◽  
Stefán Áki Ragnarsson ◽  
Hrafnkell Eiríksson
Keyword(s):  
Benthic Community ◽  
Stock Assessment ◽  
Benthic Communities ◽  
Fishing Effort ◽  
Early Years ◽  
Total Catch ◽  
Macrobenthic Communities ◽  
Modiolus Modiolus ◽  
Cucumaria Frondosa

Abstract Effects of scallop dredging on benthic communities in Breidafjordur, west Iceland, were investigated by analysing bycatch data from scallop stock assessment surveys and effort data from the commercial scallop fishery. Bycatch constituted 28% of the total catch, with eight benthic macrofaunal taxa alone making up nearly 98% of the bycatch. Modiolus modiolus and Cucumaria frondosa dominated in terms of abundance and biomass in most of the study area regardless of intensity of fishing effort, although both have been identified as sensitive to fishing in other studies. The macrofaunal benthic community in Breidafjordur consisted mostly of hard-shelled molluscs, holothurians, crabs, and starfish. Emerging epifauna was absent in the samples taken since 1993. These results suggest that our study was carried out within an already altered community that would have suffered the greatest impact during the early years of the scallop fishery. However, the available data are not enough to endorse this assumption with complete certainty.

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