Insights from the Niger Delta Region, Nigeria on the impacts of urban pollution on the functional organisation of Afrotropical macroinvertebrates.

Anthropogenic activities, including urbanisation and industrialisation threaten stream ecological integrity, ecosystem community structure and ecosystem functioning of rivers and streams worldwide. However, developing sustainable monitoring strategies for ecological health remains a critical challenge in Africa. We examined the effects of urban disturbance on macroinvertebrate Functional Feeding Groups in selected streams in the Niger Delta Region of Nigeria. We sampled 11 sites between 2008 and 2012 and grouped into three site groups (Site groups 1 > 2 > 3). The groups represent an increasing gradient of urban pollution. Our result showed that urban-induced disturbances affected physicochemical variables in the study area (PERMANOVA; p < 0.05), with nutrients NO2-N, PO4-P, and electrical conductivity being significantly higher in impacted Site group 3 (ANOVA, p < 0.05). Predators and gatherers were the most dominant Functional Feeding Group recorded in the study area, while shredders were the least abundant macroinvertebrate Functional Feeding Groups. The multivariate RLQ analysis revealed that shredders, predators, and scrapers were tolerant of urban pollution, whereas gatherers were sensitive to increasing urban pollution. Overall, macroinvertebrates Functional Feeding Groups responded differentially to urban pollution in the Niger Delta Region. Identifying pollution indicator Functional Feeding Groups is seen as an important step towards developing a reliable, low-cost tool for riverine monitoring of urban pollution effects in Africa.

Functional groups of Afrotropical EPT (Ephemeroptera, Plecoptera and Trichoptera) as bioindicators of semi-urban pollution in the Tsitsa River Catchment, Eastern Cape, South Africa.

We examined the distribution patterns of Ephemeroptera, Plecoptera, and Trichoptera functional feeding groups (EPT FFGs) in five streams that drain semi-urban landscapes in the Tsitsa River catchment, Eastern Cape Province of South Africa. We undertook macroinvertebrate and physicochemical analysis over four seasons between 2016 and 2017 at eight sites in three land-use categories (Sites 1, 2 and 3), representing an increasing gradient of semi-urban pollution. Five EPT FFGs (shredders, grazers/scrapers, predators, collector-gatherers and collector-filterers) were fuzzy coded and analyzed using RLQ-R (environmental characteristics of samples), L (taxa distribution across samples) and Q (species traits) and fourth-corner analyses. Physicochemical variables, including phosphate-phosphorus, total inorganic nitrogen and temperature, were the most influential variables that significantly influenced the distribution patterns of EPT FFGs in the Tsitsa River. RLQ and the fourth-corner model revealed varying responses of FFGs to semi-urban pollution. Of the five FFGs, collectors were the most abundant EPT FFGs in the study area, exhibiting disparate responses to disturbances, with collector-gatherers associated with impacted sites and significantly associated with phosphate-phosphorus. On the other hand, collector-filterers decreased with increasing semi-urban disturbance and exhibited a significant negative association with phosphate-phosphorus, total inorganic nitrogen and temperature. Overall, this study provides further insights into the environmental factors that influence the distribution patterns of FFGs in Afrotropical streams and the potential use of FFGs as indicators of anthropogenic pollution in tropical streams and rivers.

Are zooplankton useful indicators of ecological quality in Afrotropical ephemeral stream impacted by human activities?

Ephemeral river systems in Nigeria are under severe threat by increasing anthropogenic pollution. However, little is known about the ecological health of ephemeral rivers in Afrotropical regions, especially Nigeria. It is also unclear how zooplankton communities respond to anthropogenic stressors in ephemeral rivers in the African continent. In this study, we explored the responses of zooplankton to environmental indicators of human activities to assess the health of River Kafin Hausa, an ephemeral river system in north-western Nigeria. Our specific objectives were to explore the response patterns of zooplankton communities to anthropogenic pollution in the north-western ephemeral rivers and examine their potential use as reliable indicators for long-term monitoring of ephemeral systems impacted by different human activities. We collected zooplankton and physicochemical variables from three sites in five months, from January to February and April to June 2018. One-way ANOVA showed air temperature, water temperature, pH, salinity, BOD5, phosphate and nitrate varied significantly (p < 0.05) between the sites across the 5 months. We recorded four zooplankton groups, namely Cladocera, Copepoda, Protozoa and Rotifera. The cluster analysis revealed that the organisms were grouped mainly by sites rather than by seasons. The multivariate canonical correspondence analysis (CCA) revealed a weak association between the zooplankton community assemblages and physicochemical variables. However, there were differential responses of zooplankton to physicochemical variables in the river system, with species such as Eurytemora affinis, Acartia tonse and Sinodiaptomus sarsi being sensitive, indicating positive associations with DO concentration. Conversely, species such as Macrothrix rosea and Bosmina longirostris were tolerant, demonstrating their usefulness as bioindicators of bad water quality as they associated positively with TDS, water depth, nitrates and salinity. Overall, the study revealed further insights into the responses of zooplankton communities to pollution, and their potential use as indicators organisms in ephemeral rivers.

Searching for indicator macroinvertebrate traits in an Afrotropical riverine system: implication for ecosystem biomonitoring and sustainability.

In the past three decades, macroinvertebrate traits have been explored and employed in the biomonitoring of riverine systems globally, but much attention has not been given to the trait-based approach (TBA) in Nigeria. Therefore, in this study, the distribution patterns of macroinvertebrate traits in selected stations exposed to varying degrees of perturbation in River Hadejia, north-western Nigeria, were explored to assess the ecological health of the river. Three stations were selected, representing an increasing gradient of pollution: station 1 > station 2 and station 3, and were used to search for potential indicator traits. Four traits, including body size, respiratory, mobility, and body shape, were selected and classified into 12 trait attributes. The RLQ analysis revealed macroinvertebrates possessing medium and large body sizes, climbing and crawling, tegumental, gills, and aerial: lungs respiratory traits, and streamlined body shape were associated with station 1. Conversely, macroinvertebrates possessing very small and small body sizes, aerial: spiracle and aerial/vegetation, sprawling, swimming, and skating, flattened, spherical, cylindrical, and rhomboidal were mainly associated with stations 2 and 3. In searching for potential indicator macroinvertebrate traits aside from the RLQ analysis conducted, a fourth-corner analysis was further performed, which showed traits including medium and large body sizes, tegumental, and aerial: lung respiratory traits to be sensitive to pollution. Equally, aerial/vegetation, flattened body shape, and very small body size were found to be tolerant of pollution. A more robust trait-based biomonitoring study using more trait classes such as feeding mechanism, food preferences, voltinism, and attachment mechanism is recommended for future study in this region. The study would be helpful in biomonitoring of ecosystem health and enhance the sustainability prowess of the TBA in the studied region.

Are Ephemeroptera, Plecoptera and Trichoptera traits reliable indicators of semi-urban pollution in the Tsitsa River, Eastern Cape Province of South Africa?

The taxonomy-based response pattern of macroinvertebrates to pollution gradient is well established, with tolerant taxa increasing in impacted conditions, while sensitive taxa increase with decreasing deterioration, typical of rural pollution. This study identified rural indicator and sensitive traits of Ephemeroptera, Plecoptera and Trichoptera (EPT) taxa by examining their trait distribution pattern in relation to rural pollution. Physicochemical parameters and EPT were sampled seasonally from August 2016 to April 2017. Eight sites were selected and categorised into three site groups. Site group 1 served as the least impacted site group and Site group 2 as the moderately influenced, whereas Site group 3 was the most impacted. Seven traits were selected and categorised into 27 trait modalities. The response of EPT traits to physicochemical parameters was analysed using the simultaneous analysis of the information contained in three tables: R (environmental characteristics of samples), L (taxa distribution across samples) and Q (species traits) (RLQ) and confirmed with fourth-corner analysis. Three trait attributes, large (10-20 mm), swimming, shredding, streamlined body shape and large body size (≥ 10-20), were considered tolerant signature traits of semi-urban pollution. These trait attributes were associated with the influenced Site group 3 and indicated a significant positive affinity with at least one physicochemical indicator of increasing semi-urban pollution (NH4-N, NO3-N, NO2-N, PO4-P, EC, turbidity, temperature and pH). Conversely, small body size (< 10 mm), operculate gills, spherical body shape and a preference for sediments were correlated with the least influenced Site group 1 and were considered sensitive traits of semi-urban disturbance. Overall, this study provided critical insights into EPT responses to disturbance, revealing that semi-urban activities influenced EPT traits differently in the Tsitsa River.

Ephemeroptera, Plecoptera and Trichoptera (EPT) functional feeding group responses to fine grain sediment stress in a river in the Eastern Cape, South Africa.

Sedimentation arising from agricultural run-offs, riparian habitat fragmentation and channel bank erosion has long been known to impair the structure and ecological functioning of stream and river ecosystems. This study examined the effects of fine sediment grain sizes on the functional feeding group structure of Ephemeroptera, Plecoptera and Trichoptera (EPT) in the Tsitsa River catchment in the Eastern Cape Province of South Africa. Fine sediments and EPT were sampled between August 2016 and April 2017 from eight selected sampling sites. The eight sites were classified into four groups in terms of fine sediments and turbidity to represent a gradient of sediment stress, with site groups 4 and 3 being less influenced and groups 2 and 1 as the highly influenced groups. EPT genera/species were assigned to five functional feeding groups (FFGs) and their responses to sediment stress assessed. The results of the study showed that of the five FFGs, four (i.e. collector-filterer, collector-gatherer, scraper/grazer and shredder) were significantly different between the four groups, separating the impacted groups from the less impacted groups. Redundancy analysis (RDA) showed that FFGs such as scraper/grazer, collector-gatherer and shredder were tolerant to fine sediment, especially during the dry season. Collector-filterers and predators were the most sensitive FFGs observed in the studied river systems. The RDA results showed that the coarser grain size fractions (very coarse and coarse silt, very fine sand and turbidity) displayed more severe negative effects on EPT FFGs when compared with the finer grain size fractions such as very fine and fine silt. The results obtained in this study provided more insights into the response patterns and functional dynamics of EPTs in the Tsitsa River systems, a knowledge that can contribute to trait-based biomonitoring in South Africa.

Evaluating the responses of taxa in the orders Ephemeroptera, Plecoptera and Trichoptera (EPT) to sediment stress in the Tsitsa River and its tributaries, Eastern Cape, South Africa.

Excessive delivery of fine sediment has been implicated as the main water quality stressor in the Tsitsa River catchment. This study evaluates the responses of the taxa Ephemeroptera, Plecoptera and Trichoptera (EPT) to suspended sediment and grain size distribution in eight selected study sites in the Tsitsa River catchment. The sampling of macroinvertebrates took place seasonally from August 2016 to April 2017 and EPT identified to either genus or species level. To avoid site redundancy, the sites were clustered into four groups, with groups 1 and 2 being more impacted when compared to groups 3 and 4. The results of the sediment grain size analysis revealed that sediment grain size distribution ranged from 0.121 to 5.61 µm; percent clay and percent silt were the most dominant sediment fractions across all groups. Among the EPT metrics examined, Shannon index, Simpson's index, evenness, Ephemeroptera abundance, EPT abundance and Trichoptera abundance were sensitive, differentiating between sediment groups 3 and 4 (less impacted groups) from 1 and 2 (highly impacted groups). Site groups 3 and 4 supported more EPT species, in terms of the number of individuals and diversity. Species such as Caenis sp., Pseudocloeon glaucum, Oligoneuropsis lawrencei and Baetis sp. were considered sediment-tolerant, displaying strong positive association with influenced groups. Taxa such as Hydropsyche sp., Pseudocloeon sp., Cheumatopsyche sp. and Afronurus sp. were considered sediment-sensitive. Overall, the present study revealed that genera/species within the order EPT were differentially sensitive to fine sediment stress and grain sizes, proving to be useful bioindicators.