Tega Treasure Edegbene Ovie

Freshwater systems, including urban streams and groundwater, are increasingly affected by climate change through altered precipitation, rising temperatures, droughts, floods, and changing water demand. This narrative review synthesizes evidence on how these pressures modify groundwater–stream connectivity and the resulting ecological, conservation, and sustainability implications in urban environments. The literature shows that groundwater supports baseflow, thermal buffering, hyporheic exchange, and habitat persistence, but that urbanization can simultaneously reduce natural recharge and create new anthropogenic recharge pathways. Studies of urban streams document flashier hydrographs and ecological degradation under conventional urbanization, whereas infiltration-focused low-impact development has been shown in some catchments to increase baseflow and reduce seasonal variability. Climate change adds further pressure: global modelling projects substantial warming of shallow groundwater by 2100, while long-term stream studies show taxon-specific community responses to warming and extreme events. Major knowledge gaps include limited long-term paired groundwater–stream observations, scale mismatches among hydrology, ecology, and governance, and underrepresentation of arid, semi-arid, tropical, and Global South cities. Addressing these gaps requires coupled hydrological–ecological research, functional indicators, and context-specific nature-based and hybrid management strategies that maintain or restore groundwater–stream connectivity as a component of urban freshwater resilience.

In Nigeria, pollution of freshwater ecosystems by anthropogenic activities is a matter of urgent concern as it threatens the productivity and sustainability of the ecosystems. Freshwater ecosystems...

The use of macroinvertebrates metrics, has gained popularity globally. In Hadejia River, the intersection of increasing human settlements and agricultural activities along the bank of the river have given rise to pressing environmental concern—contamination. From November 2018 to August 2019, we collected physico-chemical and macroinvertebrate samples in Hadejia River and three tributaries of the river namely Rivers Kafin Hausa, Hadiyau and Ringim. Metrics of the collected macroinvertebrates in Hadejia River were used to explore the ecological health conditions of the rivers, and also used to develop a simple multimetric index MMI (MMIhadejia) for the river. The statistical analysis using pair-wise t-tests and PERMANOVA provides insights into the comparability of various stations and seasons based on physico-chemical parameters. The metrics we identified during the test for sensitivity play a crucial role in discerning differences between the sampled stations, emphasizing their significance in biomonitoring efforts. Furthermore, seasonal stability in certain metrics in the study proved valuable for ensuring the reliability of the selected indicators over time, providing consistent information regardless of seasonal changes. Metrics such as Mollusca abundance, Coleoptera richness, and Shannon Diversity stand out as reliable indicators, offering both discriminatory power and stability across seasons. The redundancy test results revealed that Shannon Diversity and Evenness Index were deemed non-redundant. We summed up the scores assigned to each of the four metric components integrated into the MMI. The validation process for MMIhadejia showed that water quality assessment based on this validation dataset of the three tributaries of Hadejia River revealed distinct categories for each river and station.

Urban pollution is increasing at an alarming rate within the catchments of forested riverine systems in sub-Saharan Africa, Nigeria inclusive. Assessing the impact of pollution in riverine systems in the Niger Delta region is still within the use of physico-chemical variables and biota-based assemblage. In covering this important gap in freshwater biomonitoring, we developed a macroinvertebrate-based multimetric index (MMI) that would be useful in monitoring, assessing, and managing forested riverine sites affected by urban pollution. We collected macroinvertebrates and physico-chemical samples monthly at 20 sites in 11 streams. Physico-chemical variables were analysed using standard methods while a kick sampling procedure was employed in collecting macroinvertebrates. The physico-chemical variables were used to classify the sites into three disturbance categories: least-impacted sites (LIS), moderately impacted sites (MIS), and heavily impacted sites (HIS). Fifty-nine candidate macroinvertebrate metrics were selected and screened for developing our MMI. We employed sensitivity, seasonality, repeatability and redundancy tests, and metric scoring in screening and arriving at the final metrics for the MMI development. Five metrics were finally selected for the MMI development: Trichoptera abundance, %Chironomidae+Oligochaeta, Coleoptera richness, Simpson diversity, and Shannon–Wiener index. Correlation in the selected metrics with physico-chemical variables showed that Simpson diversity was negatively correlated with pH in the MIS and Coleoptera richness was positively correlated with dissolved oxygen (DO) and water depth in the LIS. Nitrate, biochemical oxygen demand (BOD), conductivity, and water temperature were negatively correlated with %Chironomidae+Oligochaeta in the HIS. This MMI can aid river and stream managers in assessing the ecological conditions of rivers and streams in the Niger Delta region of Nigeria.