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An Assessment of the Effect of Industrial and Sewage Effluent on Aquatic Invertebrates: A Case Study of A Southern Urban Stream, Zimbabwe

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Trevor Dube at University of Hertfordshire
Trevor Dube
Caston Makaka at Midlands State University
Caston Makaka
Sibanda Zwelabo
Sibanda Zwelabo
Sibanda Zwelabo
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Abstract

The impact of industrial effluent discharged in Mazai stream was assessed through physical-chemical parameters and also by bio-monitoring of benthic macro-invertebrates. Samples were collected at three sites, one before the effluent discharge point into the stream (site 3) and two sites which were located downstream after the discharge points (sites 1 and 2). High levels of chemical pollutants were recorded at sites 1 and 2 (ZINWA red category) whereas site 3 (reference site) consisted of relatively clean water (ZINWA blue category). This was confirmed by the biological evaluation process. The SASS4 scores at sites 1 and 2 indicated a deterioration of water quality while site 3 there was good water quality with high species diversity. Detrended correspondence analysis (DCA) showed that pollution sensitive taxa such as Hemiptera, Trichoptera, Coleoptera and Odonata were dominant at site 3 whilst the other sites were dominated by pollution tolerant species such Chironomids. Continuous discharge of effluent could lead to extreme degradation of Mazai stream hence loss of biodiversity of macro-invertebrates.
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Journal of Sustainable Development www.ccsenet.org/jsd
210
An Assessment of the Effect of Industrial and Sewage Effluent on
Aquatic Invertebrates: A Case Study of A Southern Urban Stream,
Zimbabwe
Dube Trevor (Corresponding author)
Department of Biological Sciences, Midlands State University, P. Bag 9055, Gweru, Zimbabwe
Tel:263 -54-260-568 ext 332 E-mail: tdube@msu.ac.zw
Makaka Caston
Department of Biological Sciences, Midlands State University, P. Bag 9055, Gweru, Zimbabwe
Tel:263-54-260-568 ext 340 E-mail: makakac@msu.ac.zw
Sibanda Zwelabo
Department of Biological Sciences, Midlands State University, P. Bag 9055, Gweru, Zimbabwe
Tel: 263-54-260-568 ext 340 E-mail: zwenilabo@yahoo.com
Abstract
The impact of industrial effluent discharged in Mazai stream was assessed through physical-chemical parameters
and also by bio-monitoring of benthic macro-invertebrates. Samples were collected at three sites, one before the
effluent discharge point into the stream (site 3) and two sites which were located downstream after the discharge
points (sites 1 and 2). High levels of chemical pollutants were recorded at sites 1 and 2 (ZINWA red category)
whereas site 3 (reference site) consisted of relatively clean water (ZINWA blue category). This was confirmed by
the biological evaluation process. The SASS4 scores at sites 1 and 2 indicated a deterioration of water quality
while site 3 there was good water quality with high species diversity. Detrended correspondence analysis (DCA)
showed that pollution sensitive taxa such as Hemiptera, Trichoptera, Coleoptera and Odonata were dominant at
site 3 whilst the other sites were dominated by pollution tolerant species such Chironomids. Continuous
discharge of effluent could lead to extreme degradation of Mazai stream hence loss of biodiversity of
macro-invertebrates.
Keywords: Stream, Macro invertebrates, Sewage effluent, Bio-monitoring, Water quality
1. Introduction
Water pollution is a major problem in the global context. The problem of water pollution is being experienced by
both developing and developed countries. Sewage disposal is of major concern in most urban areas of Zimbabwe.
Wastewater from industries and sewage spillages from burst pipes around the country are released into streams
and rivers which finally discharge into dams around the cities of Zimbabwe. With the prevailing hard economic
situation in the country, most of the trade waste effluents are released into the environment untreated or partially
treated. Industrialists have adopted the use of substandard treatment methods that partially treat and in some
instances, forego the effluent treatment process. At Thorngrove sewage works, Zimbabwe, raw sewage is at
times discharged into Mazai stream to avoid plant clogging when power cuts are experienced. The same problem
is experienced in Lake Chivero catchment where raw sewage is finding its way into Manyame, Marimba and
Mukuvisi rivers, the tributaries of the lake leading to its eutrophication (Moyo, 1997). The result is an increase in
organic pollutant loads hence increased algal growth that greatly affects aquatic invertebrate diversity (Chutter,
1972).
Most studies on water quality in Zimbabwe have been concerned with assessing the physico-chemical
parameters of water (Mathuthu et al., 1997; Moyo and Worster, 1997, Magadza, 2003, Ndebele, 2009). This
study investigates the diversity of aquatic invertebrates in relation to pollutant levels in Mazai stream, a tributary
of Umguza dam in Bulawayo.
2. Materials and Methods
The study was conducted in Mazai stream of Bulawayo, Zimbabwe. The stream runs from Donnington industrial
area past Belmont, Steeldale, Thorngrove industrial areas and finally past Thorngrove sewage works effluent
discharge point (Figure 1). The stream eventually drains into Umguza dam. Water from Umguza dam is mainly
used for capture fisheries by locals and irrigation purposes by Ingwebu farm. Three sampling sites were selected
along the stream. Site 1 was at Khami Road Bridge, a point where industrial effluent is discharged into the
stream. Site 2 was downstream about 90 m away from the sewage discharge point at Thorngrove sewage works
and site 3 upstream of Mazai stream, before industrial waste and sewage discharge points (figure 1). This was
taken as a reference point with relatively clean water.
Water samples were collected over a period of six months from April 2009 to October 2009. Sampling was done
once each month. Two replicate samples were collected for each parameter and the mean results calculated.
Samples for chemical analysis, nitrates, phosphates, permanganate value and ammonia were collected into 1000
Journal of Sustainable Development Vol. 3, No. 2; June 2010
211
ml water bottles and refrigerated at low temperatures (< 4oC) prior to laboratory analysis. Temperature readings
were recorded at the sampling sites using a mercury bulb thermometer. A Mettler Toledo 320 pH meter was used
to measure pH. A Mettler Toledo MC 226 conductivity meter was used to measure conductivity. Total nitrogen
and total phosphorus concentrations were determined in the laboratory with Hach nutrient analysis kits and a
Hach spectrophotometer (DR010 Hach Co., Loveland, Colorado, USA). Turbidity levels were measured in
Nephelometric units (NTUs) using the HACH 2100A turbidity meter. Macro-invertabrates were collected using
the kick sampling method at each site (Chutter, 1994). Samples for aquatic invertebrates were collected into
collecting bottles and preserved using 10 percent buffered Formalin.
2.1 Data Analysis
Analysis of variance (ANOVA) was used to compare the physical and chemical parameters amongst the three
sites. The South African Scoring System (SASS4) was used as a biotic index for evaluating the river ecosystem
health (Chutter, 1998). Shannon-Weiner index was used to evaluate abundance and evenness of
macro-invertebrates amongst the three sites. Species occurrences were ordinated using PAST version 1.95 (Past
1999- 2009). Detrended correspondence analysis (DCA) was used to examine possible gradients in species
composition (Hill & Gauch, 1980).
3. Results
3.1 Chemical parameters of water from Mazai stream
The levels of ammonia decreased from site 1 to site 3 (S1 > S2 > S3) (Table 1). There were significant
differences in the levels of ammonia amongst the three sites (ANOVA, F(2,6) = 27.00 < Fc = 134.4, p = 0.001).
This was also true for phosphates (ANOVA, F(2,6) = 5.14 < Fc = 6.167, p = 0.05). This trend also applied for
permanganate value (PV) (Table 1). Site 1 had 63.3 mgL-1 whereas sites 2 and 3 were 36 and 4 mgL-1
respectively (ANOVA , F(2,6) = 27.0 < Fc = 57.743, p = 0.001). However the levels of nitrates were slightly higher
at site 2 than sites 1 and 3 (S2 > S1 > S3). There were no significant differences in the levels of nitrates
amongst the sites (ANOVA, F(2,6) = 5.14 > Fc = 3.66, p = 0.05).
The mean values for all chemical parameters in sites 1 and 2 fell under the Zimbabwe National Water Authority
(ZINWA) Red category (range; ≤ 40 mgL-1 for PV, ≤ 5 mgL-1 for phosphates and ≤ 2 mgL-1 for ammonia) whilst
those from site 3 comply with the Blue permit range (≤ 0.5 mgL-1 for ammonia, ≤ 3 mgL-1 for nitrates, ≤ 0.5
mgL-1 for phosphates and ≤ 5 mgL-1for PV). The Red category denotes high hazard or bad water quality whilst
the blue category denotes safe water or good water quality.
Conductivity levels decreased from site 1 to site 3 (S1 > S2 > S3) (Table 1). There were significant differences in
the conductivity levels amongst the three sampling sites (ANOVA, F(2,6) = 27.0 < 40.391, p = 0.001). However
the pH and temperature levels were slightly higher at site 2 than sites 1 and 3 (S2 > S3 >S1). There was no
significant difference in pH levels amongst the sampling sites (ANOVA, F(2,6) = 5.14 > Fc = 4.926, p = 0.05). pH
levels were slightly acidic (6.8) at site 1 but slightly alkaline (7.3) at site 2. pH levels at reference site 3 were
neutral. Samples from site 1 and 2 were highly turbid whereas the turbidity for site 3 normal and under the
ZINWA Blue limit (range ≤ 5 NTU). The mean values for conductivity in sites 1 and 2 were in the ZINWA Red
category (range ≤ 3500 µScm-1) whilst those from site 3 comply with the Blue permit range of ≤ 200 µScm-1.
3.2 Biological assessment of water quality
3.2.1 Composition and spatial variation of benthic invertebrates
Between April and December 2009, benthic invertebrate fauna from 12 taxonomic orders were collected from
Mazai stream. The most abundant taxa in terms of relative frequency were Hemiptera > 40 % at site 3 followed
by Chironomidae (> 24 % at sites 1 & 2) and Oligochaeta (19 % at site 2) (Table 2). Rare taxa included
Nematoda, Megaloptera and Plecoptera whose relative frequencies were less than 4 %. Highest diversity of taxa
was at site 3 (H' = 1.5) compared to sites 1 and 2 (H' = 1.25 & H' = 1.39) respectively (Table 3).The evenness of
distribution of pollution sensitive taxa was low at site 3 (E = 0.6) compared to pollution tolerant taxa at sites 1
and 2 (E = 0.9 & E = 0.8) respectively.
The first two axis of the DCA ordination accounted for most of the variation in the species data with eigen values
of 0.47 and 0.09 for axis 1 and 2 respectively. The first two axis explained 59.6 % of the total variation. The
gradient length was 1.73 and 0.99 for these axes. The first axis thus corresponds to the most important gradient
in the species data. It reflects variation in species amongst the three sites. Site 3 was dominated by pollution
sensitive taxa (Hemiptera, Trichoptera. Coleoptera and Plecoptera) whilst sites 1 and 2 were dominated by
pollution tolerant taxa (Simulidae, Chironomidae, Hirudenea and Oligochaeta) (Figure 2).
3.2.2 SASS score as indicator of water quality
The SASS4 score at site 1 was 10 and the ASPT was 2.5 indicating a major deterioration in water quality. The
SASS4 score at site 2 was 25 and the ASPT was 4.17 also showing major deterioration in water quality. This was
in contrast to site 3 where the SASS4 score was 134 and ASPT was 13.4 showing good water quality (Table 3).
4. Discussion
According to Chutter (1998), there is major deterioration in water quality in Mazai stream after the industrial
Journal of Sustainable Development www.ccsenet.org/jsd
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effluent discharge sites. Physico-chemical parameters were relatively high at sites 1 and 2 compared to site 3
indicating high pollution levels. Industrial effluents contributed a relatively high percentage of pollutants in
Mazai stream. High ammonia levels were noted at sites 1 and 2. The NH3-pH equilibrium contributed to low
diversity of macro-invertebrates at these sites. It has been established that the toxic effect of ammonia is directly
related to the concentration of the unionized form (Moyo and Worster, 1997; Camargo et al., 2005). In its
normal state ammonia has little or no effect on aquatic life forms. Ammonia exists either in the ionized form
(NH4+) or the unionized form (NH3). Fish kills in Lake Chivero in 1996 before the turnover period were mainly
due to ammonia toxification of water bodies which has exactly the same effects on other aquatic life forms such
as macro-invertebrates (Magadza, 1997; Moyo, 1997). The ammonia values at sites 1 and 2 are in the Red permit
classification indicating poor water quality whereas that of site 1 complies with the Blue permit indicating safe
water quality (Statutory Instrument, 2007). Phosphate levels were extremely high at site 1 almost twice the value
at site 2 which is also classified under the Red category (Statutory Instrument, 2007).
The overall water quality through assessment by physico-chemical parameters were in the Blue range at site 3
compared to the Red classification of sites 1 and 2. The results obtained through chemical analysis of Mazai
stream are directly related to those derived from the SASS4 scoring. Higher diversity of pollution tolerant
species such as chironomids, nematodes, Simuliidae and the leeches dominated sites 1 and 2. These organisms
are able to survive under extreme toxic pollutant conditions including low oxygen levels (Micheal and Kelso,
2007). The environment at site 1 is inhospitable since pollutant tolerant macro-invertebrates were also showing
very low species richness. Site 2 was also dominated with pollutant tolerant organisms though there is
resurgence of moderately sensitive macro-invertebrates. This might possibly be a result of dilution effect from
site 3 which contributes clean water into Mazai stream and the self purification process (Machena, 1997). The
macro-invertebrates from site 3 included Trichoptera, and Plecoptera which are strictly freshwater species with
high susceptibility to toxic pollutant, inorganic pollutants and anoxic conditions (Allan, 1995). Their presence
indicates good water quality implying that it is actually possible to maintain Mazai stream in good condition if
strict measures are exercised on effluent disposal.
High oxygen is required to oxidize the inorganic pollutants at site 1 as shown by the high permanganate value.
The final on macro-invertebrates is that it tends to reduce macro-invertebrate diversity at these sites. The
permanganate value lies in the Blue permit range at site 3 which is confirmed by the SASS score obtained. Sites
1 and 2 show an assemblage of macro-invertebrates from the low oxygen tolerant group to the moderately low
oxygen tolerant species (Connolly et al., 2004).
Mazai stream eventually discharges into Umguza dam. High phosphates and nitrates levels may contribute to the
eutrophication of Umguza dam (Ndebele, 2009). Regulating effluent discharge from the industries and sewage
works will significantly reduce the risk of pollution at Umguza dam. The accumulation rate of these nutrients
will continue than it can be naturally controlled through the self purification process. The distance from the
discharge sites to Umguza dam is less than 10 kilometers implying that it is difficult for self purification of
Mazai stream to be effected (Yoshida & Yasui, 1992; Machena, 1997; Mehrdadi et al., 2006). This is a result of
high accumulation rates coupled with diffuse cases of sewage leakages from the sorrounding residential areas
Makhokhoba, Mzilikazi,Trenance and Richmond.
The nutrient concentrations will continue to rise as the volume of sewage effluent increases caused by increasing
population density in the city and the need to increase the production in the industrial areas. Strict measures
should be exercised by the local authority to ensure that industrial effluent discharged into streams is treated.
There is also a need to revise penalties for the different ZINWA categories so as to discourage pollution by
industrialists.
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Ta bl es
Table 1. Mean values (± standard deviation) of chemical and physical parameters of water from Mazai stream
Parameter Site 1 Site 2 Site 3
Ammonia (mgL-1) 21.94 ± 1.81 8.16 ± 2.22 0.01 ± 0
Nitrate (mg L-1) 1.40 ± 0.5 2.07 ± 1.5 0.09 ± 0.01
PV (Absorbed O2 mg L-1) 63.33 ± 9.24 36.00 ± 6.93 4.00 ± 2
Phosphate (mgL-1) 11.62 ± 6.32 6.75 ± 0.56 0.97 ± 1.11
Conductivity (mScm-1) 89.67 ± 1.81 81.00 ± 7.2 53.67 ± 3.06
pH (units) 6.83 ± 0.12 7.30 ± 0.26 7.03 ± 0.06
Temperature (oC) 22.0 ± 2.89 25.33 ± 0.58 23.00 ± 0
Turbidity (NTU) - - 0.1 ± 0
Table 2. Total number (n) and percentage (%) of benthic macro-invertebrates caught at the 3 sites in Mazai
stream
Taxon Site 1 Site 2 Site 3
n % n % n %
Coleoptera 0 0 0 0 4 6.9
Decapoda 0 0 0 0 3 5.2
Chironomiidae 6 40 7 41.2 0 0.0
Dixidae 0 0 0 0 3 5.2
Simuliidae 4 26.7 1 5.9 0 0.0
Gastropoda 0 0 2 11.8 0 0.0
Hemiptera 0 0 0 0 30 51.7
Hirudinea 4 26.7 0 0 0 0.0
Megaloptera 0 0 0 0 1 1.7
Nematoda 1 6.7 0 0 0 0.0
Odonata 0 0 2 11.8 11 19.0
Oligochaeta 0 0 5 29.4 0 0.0
Plecoptera 0 0 0 0 1 1.7
Trichoptera 0 0 0 0 5 8.6
15 17 58
Journal of Sustainable Development www.ccsenet.org/jsd
214
Table 3. SASS4 score, diversity (H') and eveness (E) of benthic macro-invertebrates in Mazai stream
Sampling Site SASS4 Score Number of Families ASPT H1E
1 10 4 2.5 1.25 0.8
2 25 5 4.17 1.39 0.8
3 134 8 13.4 1.52 0.6
Figures
Figure 1. Map showing sampling sites in Mazai stream
Figure 2. DCA ordination of macro-invertebrate samples in Mazai stream
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  • Jun 2017
This study aimed at assessing heavy metal pollution in soil at a cable manufacturing company. The concentrations of five heavy metals which are Cu, Cd, Ni, Pb and Zn in these soils were investigated. Soil samples were collected starting from March 2015 to September 2015 by considering dry and wet seasons. The study reveals that the concentrations of heavy metals studied in soils of Burn Out Oven (BOO), Pickling Plant (PP) Cathode Cutting (CC), Metal site (MS), and Control site (CS) in dry season were higher than those in wet season at the depth of 0-10cm than 10-20cm.The data obtained was analysed using one way ANOVA significant differences were accepted at p<0.05.There was a significant difference in metal concentration recorded for Cu,Ni,Pb,Cd and Zn(p<0.05) between sites. The concentration of Cu, Ni and Zn were above USEPA (1991) maximum permissible limits at BOO,PP ,MS and CC. The Contamination Factor (CF) for all heavy metals was > 6 except for Cd in all selected productivity sites. The initial test conducted shows that waste from different processes at the company are sources of heavy metal pollution. The study recommends the organisation to monitor the copper recycling process in order to prevent soil pollution and encourages local regulatory bodies to formulate legislation that govern soil pollution by heavy metals
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... The Coleoptera was completely absent at the impacted site perhaps due to organic pollution. Trevor et al. (2010) had listed pollution sensitive taxa to include Coleoptera. The main groups of macroinvertebrates recorded during the study and their percentage contribution in the stations are presented (Table 3, Fig. 2). ...
The Influence of Abattoir Wastes on Macroinvertebrate Distribution in River Idemili, Obosi, South-Eastern Nigeria
Article
Full-text available
  • Dec 2017
The influence of abattoir wastes on macroinvertebrates distribution in River Idemili, SouthEastern Nigeria, was studied. Three sampling stations 1, 2 and 3 representing upstream of the impacted site, impacted site and downstream of the impacted site respectively were selected. The water quality characteristics, which were significantly different (p<0.05) among the study stations, include water temperature, conductivity, dissolved oxygen and biochemical oxygen demand and phosphate-phosphorus. There was no significant difference (p>0.05) in the levels of pH and nitrate-nitrogen among the study stations. Thirteen taxa composed of 201 individuals were encountered. Station 1 had the highest taxa (13) species, as well as the number of individuals (92, 45.8%), followed by station 3 with 12 species and 64 (31.8%) individuals. Station 2 had the least diversity and abundance of 6 species composed of 45 (22.4%) individuals. Macroinvertebrate abundance in the study stations were significantly different (p<0.05). Arthropoda (54.7%) was the dominant phylum. Chironomids (Family: Chironomidae) dominated the samples at all the study stations. Coleoptera was completely absent at the impacted site due to organic pollution. Margalef's species richness and Shannon Wiener index for general diversity were the highest in stations 1 and 3. The low macroinvertebrate abundance, species richness and Shannon diversity index in station 2 may be attributed to the decimating impacts of abattoir wastes entering the water in this station. Renkonen's number calculated for pairs of stations revealed that stations 1 and 3 were significantly similar, while stations 1 and 2, 2 and 3 were dissimilar. Conclusively, abattoir wastes distort water quality and affect the community structure, composition, distribution and abundance of macroinvertebrates inhabiting aquatic ecosystems.
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... The Coleoptera was completely absent at the impacted site perhaps due to organic pollution. Trevor et al. (2010) had listed pollution sensitive taxa to include Coleoptera. The main groups of macroinvertebrates recorded during the study and their percentage contribution in the stations are presented (Table 3, Fig. 2). ...
The Influence of Abattoir Wastes on Macroinvertebrate Distribution in River Idemili, Obosi, South-Eastern Nigeria
Article
Full-text available
  • Dec 2017
The influence of abattoir wastes on macroinvertebrates distribution in River Idemili, SouthEastern Nigeria, was studied. Three sampling stations 1, 2 and 3 representing upstream of the impacted site, impacted site and downstream of the impacted site respectively were selected. The water quality characteristics, which were significantly different (p<0.05) among the study stations, include water temperature, conductivity, dissolved oxygen and biochemical oxygen demand and phosphate-phosphorus. There was no significant difference (p>0.05) in the levels of pH and nitrate-nitrogen among the study stations. Thirteen taxa composed of 201 individuals were encountered. Station 1 had the highest taxa (13) species, as well as the number of individuals (92, 45.8%), followed by station 3 with 12 species and 64 (31.8%) individuals. Station 2 had the least diversity and abundance of 6 species composed of 45 (22.4%) individuals. Macroinvertebrate abundance in the study stations were significantly different (p<0.05). Arthropoda (54.7%) was the dominant phylum. Chironomids (Family: Chironomidae) dominated the samples at all the study stations. Coleoptera was completely absent at the impacted site due to organic pollution. Margalef's species richness and Shannon Wiener index for general diversity were the highest in stations 1 and 3. The low macroinvertebrate abundance, species richness and Shannon diversity index in station 2 may be attributed to the decimating impacts of abattoir wastes entering the water in this station. Renkonen's number calculated for pairs of stations revealed that stations 1 and 3 were significantly similar, while stations 1 and 2, 2 and 3 were dissimilar. Conclusively, abattoir wastes distort water quality and affect the community structure, composition, distribution and abundance of macroinvertebrates inhabiting aquatic ecosystems.
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The Investigation of Surface Water Pollution by Integrated Remotely Sensed and Field Spectral Measurement Data of Kızılırmak: A case Study
Article
Full-text available
  • Jan 2019
  • POL J ENVIRON STUD
Water quality assessment by using remote sensing and its terrestrial components is carried out in short time for larger areas. The use of remote sensing technology in monitoring and researching of water resources, a fundamental requirement for the development of countries today and in the future, is important in terms of time and cost. Pollution conditions of sea, lakes and rivers can be analyzed by using remotely sensed images. Another issue that is as important as water availability today is access to quality water. It is important to investigate the availability of analysis of remotely sensed data instead of environmental, chemical analysis that determine water quality and usability. To examine the detection of water qualities without taking water samples in situ, Hafik Region was selected as study area. In this context, spectral measurements data of water samples previously taken from İmranlı (the East of the study area), where Kızılırmak River was born, and used for spectral classification of water quality was used. Matched filtering was used for integrating spectral data and CHRIS Proba image as spectral classification method. In order to conduct an accuracy analysis, chemical oxygen demand measurement was carried out at 10 points determined as 1st and 2nd water quality in the study area on the river and the lakes according to the Ministry of Environment and urbanization. The overall accuracy of classification was calculated as %70.
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Effect of low dissolved oxygen on survival, emergence, and drift of tropical stream macroinvertebrates
Article
Full-text available
  • Jun 2004
The effect of different dissolved oxygen (DO) concentrations on the macroinvertebrate assemblages from 2 Australian tropical streams (1 upland, 1 lowland) was measured using artificial stream mesocosms. Responses to 5-d exposures were tested. Both the upland and lowland assemblages showed a similar response. Most taxa tolerated all but very low DO levels (<10% saturation), although a reduction in emergence of insect taxa at intermediate levels (25–35% and 10–20% saturation) was observed. Mayflies showed the highest sensitivity to low oxygen conditions, and lethal effects were observed at DO levels <20% saturation for several upland and lowland species. For other taxa, including several Chironomidae, mortality was observed when oxygen concentrations were below 8% saturation. A drift response was observed only when oxygen concentrations reached near lethal levels (≤10% saturation). The lack of a drift response at DO concentrations of 25 to 35% and 10 to 20% saturation indicates that, in moderately poor oxygen conditions, macroinvertebrates will remain at a location and, hence, experience sublethal effects such as suppressed emergence. It is clear that these animals can persist in hypoxic conditions in the short term. However, because of sublethal effects, understanding how low DO concentrations affect natural assemblages of aquatic macroinvertebrates may require studies of populations over several generations.
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Detrended Correspondence Analysis – An Improved Ordination Technique
Article
Full-text available
  • Oct 1980
Detrended correspondence analysis (DCA) is an improvement upon the reciprocal averaging (RA) ordination technique. RA has two main faults: the second axis is often an arch or horseshoe distortion of the first axis, and distances in the ordination space do not have a consistent meaning in terms of compositional change (in particular, distances at the ends of the first RA axis are compressed relative to the middle). DCA corrects these two faults. Tests with simulated and field data show DCA superior to RA and to nonmetric multidimensional sealing in giving clear, interpretable results. DCA has several advantages. (a) Its performance is the best of the ordination techniques tested, and both species and sample ordinations are produced simultaneously. (b) The axes are scaled in standard deviation units with a definite meaning, (c) As implemented in a FORTRAN program called DECORANA, computing time rises only linearly with the amount of data analyzed, and only positive entries in the data matrix are stored in memory, so very large data sets present no difficulty. However, DCA has limitations, making it best to remove extreme outliers and discontinuities prior to analysis. DCA consistently gives the most interpretable ordination results, but as always the interpretation of results remains a matter of ecological insight and is improved by field experience and by integration of supplementary environmental data for the vegetation sample sites.
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Association of Macroinvertebrate Assemblages with Dissolved Oxygen Concentration and Wood Surface Area in Selected Subtropical Streams of the Southeastern USA
Article
Full-text available
  • Mar 2007
Woody debris (CWD) is an important habitat component in northern Gulf of Mexico coastal plain streams, where low gradients and low flows allow accumulation of CWD and promote low dissolved oxygen (DO) concentrations. We tested the influences of CWD and DO on stream macroinvertebrates experimentally by placing two surface area CWD treatments each in three concentrations of ambient DO in two streams in Louisiana, USA, with macroinvertebrates collected from ambient woody debris used as a control. We also sampled macroinvertebrates in benthic and woody debris habitats in three streams twice yearly over 2years to examine the applicability of the experimental results. Total abundance, richness (generic), and Shannon–Wiener diversity were all higher in lower DO conditions during the experiment, and total abundance was higher in the larger CWD treatment. Stream sampling corroborated the relationship between higher diversity and low DO in both benthic and woody debris habitats, but the relationship between richness and low DO only was supported in benthic habitats. Few taxa correlated with DO or CWD in the experiment (5 of 21 taxa) or stream survey (2 of 54 taxa). Whereas most taxa were uncorrelated with experimentally manipulated and in-stream measured variables, we suggest these taxa respond as generalists to stream habitat and physicochemistry. Based on this experiment and stream sampling, we believe the majority of macroinvertebrates in these streams are tolerant of seasonally low DO conditions.
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Primary production and other limnological aspects of Cleveland Dam, Harare, Zimbabwe
Article
Full-text available
  • Jun 2009
Primary production, plankton community and some limnological aspects of Cleveland dam were investigated for 15 weeks to ascertain the health of the reservoir’s ecological system. Sampling was conducted on one site near the dam wall on a weekly basis, at a 1 m interval depth profile. The sampling period (from September 2005 to January 2006) reflected the results of a hot, dry season (from September to November) and a hot, wet season (from December to January). On average, the pH, temperature, conductivity, turbidity, dissolved oxygen concentration, light penetration and photosynthetically active radiation decreased with depth. In contrast, the primary production, phytoplankton biomass, phytoplankton density, and the total nitrogen and total phosphorus concentrations did not conform to the same pattern, instead tending to increase at a depth of 4-5 m below the water surface, suggesting it was the optimum plankton habitat. There were no significant differences between depths for all parameters, suggesting that the reservoir, although exhibiting signs of stratification, was nevertheless too shallow to exhibit the varied differences down a vertical profile typical of tropical reservoirs, at least during the sampling period of this study. Although the present limnology of Cleveland Dam confirms its oligotrophic nature, the conditions prevailing in its catchment could ultimately lead to adverse effects in the reservoir. The ecological health of Cleveland Dam is discussed in regard to land use patterns in the catchment that pose threats as potential pollution sources. Cleveland Dam is possibly in danger of being polluted. There is a need to address the legal instruments currently in place for water management in order to curb such environmental degradation as they do not adequately address the problems faced.
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EVALUATION OF THE QUALITY AND SELF PURIFICATION POTENTIAL OF TAJAN RIVER USING QUAL2E MODEL
Article
Full-text available
  • Jan 2006
Tajan River is among significant rivers of Caspian Sea water basin. Pollution sources that threaten the quality of water in Tajan River may be classified in to two categories namely point and non-point sources. Major pollutants of latter category are Mazandaran wood and pulp, Paksar dairy products and Sari Antibiotic production factories, as well as 600-dastgah residential area. On the other hand, non-point sources whose waste is considered as a distributed load consist of Sari municipal wastewater and agriculture-related pollutants that are drained towards the river. In order to model the quality of river flow, Qual2E model is taken in to consideration. Considering TDS, the river quality is completely acceptable in cold seasons. However, in spring and summer the value of this parameter is increased and this causes some restrictions in the use of this water for irrigation of specific sensitive crops. Agricultural activities and consequent irrigated waters are the major causes of higher reported TDS values in warm seasons. Current status of DO is completely acceptable and this is highly related to the relative high value of width on depth ratio along the river. BOD and COD locate in a fairly poor condition. Quality deterioration is more noticeable in cold seasons. Higher rate of precipitation and consequent greater runoff generation towards the river basin justify the relative increase of mentioned parameters in fall and winter. Generally, non-point pollution sources are more contributed in deterioration of Tajan River water quality.
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Lake Chivero: A management case study
Article
  • Jun 2003
Lake Chivero in Zimbabwe was shown to be hypereutrophic. Historical data showed that the eutrophication process had been arrested in the late 1970s. However, a combination of poor planning, multiplicity of jurisdiction, mismatch between rate of urbanization and waste management investment, recent changes in the local climate and a permissive, immature political system that called for no public accountability resulted in environmental management breakdown leading to hypereutrophication of the lake. The case of Lake Chivero is presented as an example of a wider global issue regarding the status of environmental management in competition with other priorities in emerging democracies.
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Nitrate Toxicity to Aquatic Animals: A Review With New Data for Freshwater Invertebrates
Article
  • Apr 2005
  • CHEMOSPHERE
Published data on nitrate (NO3-) toxicity to freshwater and marine animals are reviewed. New data on nitrate toxicity to the freshwater invertebrates Eulimnogammarus toletanus, Echinogammarus echinosetosus and Hydropsyche exocellata are also presented. The main toxic action of nitrate is due to the conversion of oxygen-carrying pigments to forms that are incapable of carrying oxygen. Nitrate toxicity to aquatic animals increases with increasing nitrate concentrations and exposure times. In contrast, nitrate toxicity may decrease with increasing body size, water salinity, and environmental adaptation. Freshwater animals appear to be more sensitive to nitrate than marine animals. A nitrate concentration of 10 mg NO3-N/l (USA federal maximum level for drinking water) can adversely affect, at least during long-term exposures, freshwater invertebrates (E. toletanus, E. echinosetosus, Cheumatopsyche pettiti, Hydropsyche occidentalis), fishes (Oncorhynchus mykiss, Oncorhynchus tshawytscha, Salmo clarki), and amphibians (Pseudacris triseriata, Rana pipiens, Rana temporaria, Bufo bufo). Safe levels below this nitrate concentration are recommended to protect sensitive freshwater animals from nitrate pollution. Furthermore, a maximum level of 2 mg NO3-N/l would be appropriate for protecting the most sensitive freshwater species. In the case of marine animals, a maximum level of 20 mg NO3-N/l may in general be acceptable. However, early developmental stages of some marine invertebrates, that are well adapted to low nitrate concentrations, may be so susceptible to nitrate as sensitive freshwater invertebrates.
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An impirical biotic index of the quality of water in South African streams and rivers The Rapid biological assessment of Stream and River water quality by means of Macro invertebrate community in
  • 16
  • F M Chutter
Chutter, F.M. (1972). An impirical biotic index of the quality of water in South African streams and rivers. Water Research, 6:16 Chutter, F.M. (1994). The Rapid biological assessment of Stream and River water quality by means of Macro invertebrate community in South Africa: Progress Report to the Water Research Commission, Pretoria, South Africa
The self purification capacity of the Mukuvisi river
  • Jan 1997
  • C Machena
Machena, C. (1997). The self purification capacity of the Mukuvisi river. In N.A.G Moyo (Eds) Lake Chivero, a polluted lake. University of Zimbabwe Publications, Harare, Zimbabwe.