Zambian Invertebrate Scoring System (ZISS): A macroinvertebrate-based bioticindex for rapid bioassessment of southern tropical African river systems
HF Dallas1* , S Lowe2, MP Kennedy3, K Saili4 and KJ Murphy2
ABSTRACT
An extensive survey of tropical rivers, conducted during 2009–2012 throughout Zambia, collected 151 samples of benthic macroinvertebrates, located on 95 rivers in six of the nine freshwater ecoregions. Associated data for physico-chemistry, human activities and ecosystem stressors were collected. Data were used to develop and test a new Rapid Bioassessment Protocol (the Zambian Invertebrate Scoring System: ZISS) for assessment of water quality and river condition in both wadeable and non-wadeable rivers. ZISS, which is based on the South African Scoring System (SASS), includes a total of 85 taxa, of which 79 are shared with SASS. Assignment of
sensitivity weightings to new ZISS taxa was based on sensitivity weightings of closely related SASS families; known life-history modes and anatomical adaptations; and correlation of occurrence to impact ratings. The ability of the ZISS to measure impacts was assessed by determining the relationships between ZISS metrics and impacts. ZISS data for the Kafue River demonstrated the efficacy of the ZISS for detecting moderate to high impacts on water quality and river condition. ZISS represents a major step in developing a user-friendly, widely applicable, macroinvertebrate-based biotic index, which can provide easily interpretable assessments of river condition for
southern tropical African rivers.
Keywords: benthic invertebrate, biomonitoring, ecosystem stressor, freshwater ecology, Kafue River, river condition, Zambia
Physico-chemical and Water Quality Index analysis of the Okhuaihe River,
Edo State, Nigeria
NK Egun1* and CU Ogiesoba-Eguakun2
ABSTRACT
The water quality of the Okhuaihe River, Edo State, Nigeria was investigated from February to June 2016 to determine its suitability for drinking and other domestic purposes. Water samples collected from three stations were tested for fifteen physico-chemical parameters using standard analytical procedures. Biochemical oxygen demand and sodium were significantly different across the three stations. Except for calcium and iron, all other parameters were within the permissible limits recommended by the Nigerian Standard for Drinking Water Quality (NSDWQ) and World Health Organization (WHO). Water Quality Index (WQI) values ranged from 9.17 to
10.40, indicating excellent water quality. Although the quality of the water from the Okhuaihe River is suitable for drinking and domestic usage, regular monitoring of human activities along the water front and control of effluents discharged into the river is recommended to sustain and improve water quality.
Keywords: drinking water, effluent, human activities, permissible limits, pollution, water quality
The introduction, spread and ecology of redclaw crayfish Cherax quadricarinatus
in the Zambezi catchment
RJ Douthwaite1* , EW Jones2, AB Tyser1 and SM Vrdoljak3
ABSTRACT
Two of the four crayfish species brought to Zambia for aquaculture since 1979 are now naturalised. Procamburus clarkii occurs in the Maramba River at Livingstone, close to a former fish farm, whereas Cherax quadricarinatus, deliberately introduced to a number of sites in the Zambezi and Kafue River catchments since 2001, is now widespread and highly invasive. High rates of dispersal, up to 111 km y−1 downstream, might be the result of passive transport on floating vegetation. Significantly more synodontid Synodontis sp. catfish were caught in Fladen traps in the Kafue River in crayfish-free areas compared with crayfish-infested areas, but the possibility that synodontids became trap averse in the presence of crayfish was not ruled out. No difference was found in the numbers of Single-spined River Crab Potamonautes unispinus caught in crayfish-free and infested areas. Alien temnocephalans, commonly found on crayfish, are now also present on crabs P. unispinus on the Kafue Flats. The artisanal gill net fishery has been harmed by the introduction of C. quadricarinatus and no significant commercial fishery has developed. However, without more information on the adverse impacts, and stronger fisheries regulation, there is a high risk C. quadricarinatus and P. clarkii will be introduced to uninfested catchments with
irreversible consequences for artisanal fishermen and the environment.
Keywords: invasive species, Kafue River, Potamonautes unispinus, Procamburus clarkii, Synodontis
Shell morphometrics and growth rate of the invasive bivalve mollusc
Mytilus galloprovincialis in the Knysna estuarine embayment, South Africa
AN Hodgson1,2 , L Claassens1,2 and S Kankondi1
ABSTRACT
Shell morphometrics of the invasive mussel Mytilus galloprovincialis were compared at five sites and growth rate at four sites (in four seasons) in the Knysna estuarine embayment. Mussels from two sites (The Heads, Leisure Isle) where wave action was present had shells significantly lower for any length when compared with other more sheltered sites. There was no significant difference in shell width of mussels for any given length among sites. Mussels from The Heads had thicker shells than other sites, and those from Leisure Isle thicker shells than three other embayment sites where shells did not differ in thickness. Growth rate of mussels at two embayment sites
(Thesen’s Wharf and Thesen Islands Marina) was greatest in autumn and summer whereas at The Heads and Leisure Isle there was little seasonal difference in growth rate. Growth rate of mussels at Thesen’s Wharf and Thesen Islands Marina was mainly greater in all seasons when compared with mussels at The Heads and Leisure Isle. The more rapid growth rate of mussels at the sheltered embayment sites might in part explain why M. galloprovincialis now dominates the mid- to lower intertidal on hard substrata in this region of the Knysna estuary.
Keywords: Mediterranean mussel, Mytilidae, shell height, shell length, shell thickness
The spatial ecology of adult Labeobarbus marequensis and their response
to flow and habitat variability in the Crocodile River, Kruger National Park
MJ Burnett1* , GC O’Brien2, V Wepener3 and D Pienaar4
ABSTRACT
The spatial movement of Labeobarbus marequensis was evaluated by attaching radio transmitters to 16 adult fish and tracking them from August 2009 to July 2012 in the Crocodile River, Kruger National Park, South Africa. Monthly monitoring surveys acquired 1 620 manual and 64 499 remote observations. Results showed adult L. marequensis did not participate in any migrations. Habitat preferences for L. marequensis were deep runs and fast glides, and there was disproportionately high use of submerged boulders as a cover feature. Tagged individuals also made use of rapids and pools, however, avoided shallow sandy slow glides. There was a reduced activity response of tagged individuals to rapid changes in water discharge. Continued changes in flow and instream habitat might threaten the Crocodile River population. Additional investigation into the effect of altered flows and associated habitat availability to the movement of L. marequensis is needed to better understand the effect of anthropogenic water resource use on L. marequensis in the Crocodile River.
Keywords: biotopes, cover feature, diel movement, radio-telemetry, water discharge, yellowfish
Intraspecific morphological divergence in two Cichlid species from Benin
Luke M Bower1*, Laith A Jawad2, Pierre M Gnohossou3 and Ayoko Géraldine Tossou3
ABSTRACT
Selection on morphological traits can vary across the range of species, inducing a mosaic of phenotypes across populations. Intraspecific morphological divergence had been demonstrated for many fish groups inhabiting environments with varying abiotic or biotic selective pressures. Such intraspecific phenotypic variation can have a strong influence on the ecologies of species. In the current study, we examined patterns of intraspecific morphological divergence between two populations of Sarotherodon melanotheron and Coptodon guineensis in Lake Ahémé and Porto-Novo lagoon, Benin. Using multiple morphological traits, we demonstrated intraspecific morphological divergence between Lake Ahémé and Porto-Novo lagoon for these species. However, evidence for parallel divergence was found for these two species, implying a similar response to selective pressures might have been acting on labile traits. In addition, species specific morphological changes observed in the current study might be because of differing responses to similar selective forces or taxon-specific selective forces acting on labile traits. The intraspecific trait divergence demonstrated in the current study suggests several possible selective pressures acting on these populations, yet the cause of this divergence remains unknown and additional studies are required to test these inferences.
Keywords: Cichlidae, Coptodon guineensis, parallel divergence, phenotypic variation, Sarotherodon melanotheron, selective pressures
Oxidative stress responses of juvenile catfish, Clarias gariepinus exposed to
potassium dichromate at sublethal concentrations in south-eastern Nigeria
FN Ekeh1, EN Ekechukwu1, CI Atama1, FI Ezenwajiaku1, CM Ohanu1, JI Nzei1, ION Aguzie1, GE Odo1* and UME Dibuah2
ABSTRACT
The oxidative stress responses of Clarias gariepinus exposed to potassium dichromate at sublethal concentrations for 28 days were studied in 2017. Fish were exposed to 0.165, 0.0825 and 0.033 mg l −1 corresponding to 1/10, 1/20 and 1/50 of the 96 h LC50 of 1.65 mg l−1. Haematological parameters of fish decreased in haemoglobin when compared with the control and there was reduction of mean corpuscular haemoglobin concentration, mean corpuscular haemoglobin and mean corpuscular volume in presence of potassium dichromate. Significant increase in white blood cells throughout the duration of exposure and decrease in lymphocytes were observed. The lipid peroxide levels were increased in test concentrations when compared with controls of liver and gill. The fish group was subjected to oxidative stress, because of lipid peroxidation in response to reactive oxygen species generation. Gill and liver tissues showed concentration and time dependent significant increase (p < 0.05) in values of malondialdehyde, catalase and superoxide dismutase, whereas there was reduced glutathione. Similarly, potassium dichromate enhanced levels of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase as both concentration and time dependent when compared with control. Micronuclei induction was highest (7.55) on day 14 in all concentrations in the peripheral blood cells. There were alterations in values of glutathione peroxidase, superoxide dismutase, and catalase during exposure and recovery periods.
Keywords: antioxidant enzyme, biochemistry, catfish, haematology
Human health risks of metalloids and metals in muscle tissue of silver carp
Hypophthalmichthys molitrix (Valenciennes, 1844) from Lake Flag Boshielo,
South Africa
JR Sara1*, SM Marr2,3,4 , NM Chabalala1,5, WJ Smit1, LJC Erasmus6 and WJ Luus-Powell1
abstract
The Olifants River, a major tributary of the Limpopo River, is one of the most polluted rivers in South Africa. Consequently, concerns regarding the human health impact of long-term consumption of fish from the Olifants River have been raised in recent studies. Nevertheless, Lake Flag Boshielo situated on the main stem of the Olifants River has been proposed as a site for an inland fishery. Planktivorous silver carp Hypophthalmichthys molitrix (Valenciennes, 1844) is among the potential target species for such a fishery. Therefore, a desk-top human health risk assessment was conducted for silver carp from Lake Flag Boshielo. From January to November 2013, muscle samples from 50 specimens were collected and analysed for metals and metalloids. The hazard quotient based on a weekly meal of 150 g exceeded the acceptable level for As, Cd, Cr, Co, Pb, Hg, Se, V and Zn. Compared with previous studies from Lake Flag Boshielo, muscle tissue concentrations of As, Cr, Pb, Hg, Se, V and Zn for H. molitrix were higher. Based on the metal and metalloid concentrations reported in this study, long-term consumption of silver carp from Lake Flag Boshielo might pose a health risk to impoverished rural communities.
Keywords: average daily dose, hazard quotient, metal contaminants, Olifants River
Heavy metal concentrations in water and sediment of the Steelpoort River,
Olifants River System, South Africa
A Addo-Bediako*, K Matlou and E Makushu
ABSTRACT
Steelpoort River has been adversely affected by human activities in the catchment. Water and sediment quality of the river was assessed in 2015. The concentrations of some of the metals in water were found to be high and exceeded the guideline values and the concentrations of metals in sediment were found exceeding the guideline values for Cr, Cu and Zn. The high concentrations of Cu and Zn at Site 1 and Site 2 (upstream) could have originated from anthropogenic sources, such as fertilisers and pesticides from discharge of agricultural wastes, whereas the high concentrations of Cr at Site 3, Site 4 (midstream) and Site 5 (downstream) could have originated from the mine waste, and from domestic/ industrial wastes respectively. The principal component analysis results showed two main components: PC-1 with high positive loading of Cu and Mn, and PC-2 with high positive loading of Zn. These findings indicate the presence of pollution. Therefore, control measures should be implemented to reduce river contamination from anthropogenic sources.
Keywords: anthropogenic sources, fertilisers, pesticides, pollution, principal component analysis
Physico-chemical water quality characteristics of upper Ebonyi River,
Enugu State, Nigeria
NO Nweze* and EC Eze
Department of Plant Science and Biotechnology, University of Nigeria, Nsukka, Nigeria.
abstract
The physico-chemical characteristics of upper Ebonyi River, Nigeria were assessed at four locations, from September 2014 to December 2014, using standard methods, thereby providing information for documentation and the determination of pollution status in comparison with World Health Standards. Parameters, such as colour, calcium, pH, total dissolved solids (TDS), alkalinity, chloride, dissolved oxygen (DO), silica, biochemical oxygen demand (BOD5), phosphate, nitrate, potassium and lead did not significantly differ (p < 0.05) between the locations. However, water temperature, depth, flow rate, transparency and iron differed significantly. Ambient temperature,
water temperature, colour, pH, TDS, transparency, alkalinity, chloride, calcium, DO, silica, iron, BOD5, phosphate, nitrate, potassium and lead differed significantly with time (months), whereas depth and flow rate showed no significant difference. The Water Quality Index showed a medium range. The river was moderately polluted (using BOD5 level as a pollution index: BOD5 = 2.06 ± 0.92 mg l–1), shallow (41.66 ± 9.80 cm), highly transparent (26.22 ± 4.06 cm), slightly acidic (pH 6.8 ± 0.29), free of mercury, whereas phosphate (11.72 ± 2.45 mg l−1), iron (0.44 ± 0.13 mg l−1) and lead (0.09 ± 0.03 mg l−1) levels were above Word Health Standards for drinking water quality
requirements. Water from the river should be used with caution for domestic and bathing purposes, because high lead consumption might cause saturnism.
Keywords: anthropogenic effects, iron, lead, saturnism, water pollution, water quality
