A century of human-induced environmental changes and the combined roles of nutrients and land use in Lake Victoria catchment on eutrophication

Njagi, Dennis M; Routh, Joyanto; Odhiambo, Moses; Luo, Chen; Basapuram, Laxmi Gayatri; Olago, Daniel; Klump, Val; Stager, Curt

doi:10.1016/j.scitotenv.2022.155425

Cited by 36 publications

(17 citation statements)

References 92 publications

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“…Agricultural runoff (including pesticides and herbicides), untreated industrial waste, pharmaceuticals from nearby metropolitan areas like Kisumu, Kampala and Mwanza and household sewage from lakeshore settlements are the major sources of wastes in Lake Victoria (Nassali et al., 2020). Agricultural operations surrounding Lake Victoria have significantly grown over the last three decades, resulting in high quantities of phosphorus and nitrogenous contaminants being thrown into the lake (Njagi et al., 2022).…”

Section: Resultsmentioning

confidence: 99%

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Threats to aquatic biodiversity and possible management strategies in Lake Victoria

Muthoka,

Ogello,

Outa

et al. 2023

Aquaculture Fish & Fisheries

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Lake Victoria is the second‐largest freshwater lake in the world, with a surface area of 68,800 km2. The lake is rich in natural resources that are essential to the local economy and livelihoods. However, International Union for Conservation of Nature (IUCN) ranks 76% of freshwater species endemic to the Lake Victoria Basin as threatened with extinction. The biodiversity richness of the lake is still diminishing, and the risk of species extinction is increasing. Many species are yet to be identified, and thus the number of species threatened with extinction exceeds what is currently known. Furthermore, the lake is home to species that are found nowhere else on the planet, but its protection is never given the attention it needs. Genetic diversity loss is harmful to future populations and influences sustainability of the ecosystem. The decline in Lake Victoria's biodiversity is primarily attributed to various pressing issues, including water pollution, invasive species, climate change, overexploitation and the challenges stemming from high human population density. These problems are exacerbated by inadequate regulatory enforcement and a lack of comprehensive data and information to inform and guide conservation efforts. If these factors are not addressed, they may have a detrimental impact on Lake Biodiversity. This article aims to document the main threats to aquatic biodiversity as well as potential management strategies for preventing further losses of the aquatic biodiversity in Lake Victoria. The study recommends reviewing, bolstering and reinforcing the rules and regulations governing the extraction, accessibility and discharge of nutrients into the lake. The national governments should work with local governments, non‐governmental organizations and local people to safeguard and conserve the lake's biodiversity. The national governments of the riparian nations should also reserve funds each fiscal year specifically for research that would inform effective management measures to prevent further losses of the lake's biodiversity.

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Section: Resultsmentioning

confidence: 99%

“…Man has also occupied areas that were formerly home to wildlife near aquatic habitats (Njagi et al., 2022). Hippopotamus and sitatungas, which are threatened with extinction in some areas of the LVB due to wildlife hunting, have been affected.…”

Section: Resultsmentioning

confidence: 99%

Threats to aquatic biodiversity and possible management strategies in Lake Victoria

Muthoka,

Ogello,

Outa

et al. 2023

Aquaculture Fish & Fisheries

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“…Our study confirmed a negative correlation between macrophyte diversity indicators (except for the proportion of emergent vegetation) with agricultural use and urbanised areas. Increasing agricultural intensity and urbanisation in lake watersheds leads to increased nutrient delivery to the lake littoral [ 48 , 49 ]. This leads to eutrophication, which ultimately reduces lake macrophyte diversity [ 50 ].…”

Section: Discussionmentioning

confidence: 99%

Response of Macrophyte Diversity in Coastal Lakes to Watershed Land Use and Salinity Gradient

Grzybowski

Burandt

Glińska-Lewczuk

et al. 2022

IJERPH

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Coastal lakes are subject to multiple stressors, among which land use, hydrological connectivity, and salinity have the greatest effect on their biodiversity. We studied the effects that various land cover types (CORINE) of coastal lake watersheds had on macrophyte diversity in ten coastal lakes along the southern Baltic coast as characterised by twelve phytocenotic indices: these being a number of communities, Shannon–Wiener diversity, evenness, and indices of taxonomic distinctiveness of plant communities: vegetation coverage; colonisation index; share of the phytolittoral area in the total lake area, as well as shares of nympheides, pondweeds, charophytes, marine, emerged and submerged communities in the total lake area. The effects were checked for three groups of lakes distinguished by differences in salinity–freshwater (F, 5), transitional (T, 4), and brackish (B, 1)—in which a total of 48 macrophyte communities were identified. The most abundant in aquatic phytocoenoses were lakes of T type. A partial least squares regression model (PLS-R) showed a stronger impact of land-use types in immediate vicinities and entire watersheds than the impact of physico-chemical properties of water on phytocenotic indices in the lakes. Macrophyte diversity was relatively low in urban and agricultural catchments and relatively high in forest and wetland areas. Agriculture had a negative impact on the number of macrophyte communities in F lakes and, in T lakes, on the number of macrophyte communities, biodiversity, evenness, and proportion of emerged, submerged, and marine communities. Urban areas contributed to lower values of evenness, vegetation coverage, and share of marine communities in F, but, in T, to lower the number of macrophyte communities, evenness, and proportion of submerged and marine communities. Our results confirm the significant impact of land use on macrophyte diversity in coastal aquatic ecosystems. Combined analysis of anthropogenic and natural descriptors is a prerequisite for analysing human threats to biodiversity in coastal lakes. Macrophyte community-based measures of biodiversity are sensitive indicators of anthropogenic impact on the ecological condition of coastal ecosystems.

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“…sedimentation and nutrient runoff (e.g. Vanni et al ., 2011; Abell et al ., 2011; Njagi et al ., 2022). In addition, land use change introduces numerous other stressors to the lake environment such as trace metal pollution (e.g.…”

Section: Responses Of Native Fish Communities To Disturbances In Lakesmentioning

confidence: 99%

An integrative approach to assess the impact of disturbance on native fish in lakes

Thomson‐Laing,

Schallenberg,

Kelly

et al. 2023

Biological Reviews

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Freshwater fish are in a perilous state with more than 30% of species considered critically endangered. Yet significant ecological and methodological complexities constrain our ability to determine how disturbances are impacting native fish communities. We review current methods used to assess the responses of fish communities, especially native fish, to disturbances, with a focus on lakes. These methods include contemporary population surveys, manipulative experimental approaches, paleolimnological approaches and Indigenous Knowledge and social histories. We identify knowledge gaps, such as a lack of baseline data for native fish, an inability to assess the impact of historical disturbances, stressor response dynamics in contemporary multi‐stressor environments, and natural disturbance regimes. Our assessment of the current methods highlights challenges to filling these knowledge gaps using the reviewed methods. We advocate strongly for the implementation of an integrative approach that combines emerging technologies (i.e. molecular‐based techniques in contemporary surveys and paleolimnology) and underutilised knowledge streams (i.e. Indigenous Knowledge and social histories) which should be used in concert with conventional methods. This integrative approach will allow researchers to determine the key drivers of decline and the degree of change, which will enable more informed and successful management actions.

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A century of human-induced environmental changes and the combined roles of nutrients and land use in Lake Victoria catchment on eutrophication

Cited by 36 publications

References 92 publications

Threats to aquatic biodiversity and possible management strategies in Lake Victoria

Threats to aquatic biodiversity and possible management strategies in Lake Victoria

Response of Macrophyte Diversity in Coastal Lakes to Watershed Land Use and Salinity Gradient

An integrative approach to assess the impact of disturbance on native fish in lakes

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