Catchment landscape and seasonal hydrology driving water quality in community-managed fish spawning sites of shallow Lakes Chilwa, Chiuta and Mpoto Lagoon in southern Malawi
Description
This dataset provides a comprehensive, multi-variable assessment of the environmental conditions within community-managed fish spawning sites across three shallow tropical waterbodies in southern Malawi: Lake Chilwa, Lake Chiuta, and Mpoto Lagoon. The data was collected to quantify the dual influence of overarching catchment characteristics (land use and hydrology) versus localized spatial protection on the water quality of vital inland fisheries. The dataset encompasses two distinct hydrological periods: the wet season (February 2024) and the dry season (November 2024). It contains in situ water quality readings collected via multi-parameter sondes across six designated spawning sites (categorized as protected sanctuaries or unprotected zones). Core water quality parameters include temperature, dissolved oxygen, pH, turbidity, electrical conductivity, chlorophyll-a, and dissolved nutrients (nitrates and phosphates). And this dataset also provides site-level catchment predictors derived for a 5-kilometer buffer around each spawning site. These spatial metrics include Land Use and Land Cover (LULC) changes (specifically agricultural expansion, bare soil, and dense vegetation/forest cover), estimated local population densities (WorldPop 2020), and seasonal rainfall totals. This multi-tiered data structure allows researchers to independently model variance partitioning, assess the efficacy of localized spatial closures in buffering against environmental degradation, and explore the overarching impacts of agricultural runoff and seasonal evaporative concentration in endorheic lake systems.
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Steps to reproduce
1. Water Quality Sampling: In situ water quality parameters (Temperature, DO, pH, Turbidity, EC, Salinity, Chlorophyll-a, pH) were recorded using multi-parameter water quality sondes, the YSI 6600V2, the YSI 600XL and Rinko Profiler ASTD101. Measurements were taken during the wet season (February 2024) and dry season (November 2024) across six designated community-managed spawning sites (protected and unprotected) in Lakes Chilwa, Chiuta, and Mpoto Lagoon. 2. Nutrient Analysis: Water samples were collected at each station, filtered and analyzed in the laboratory for dissolved nutrients (Nitrates and Phosphates) following standard APHA limnological protocols. 3. Catchment Spatial Analysis: A 5-kilometer spatial buffer was established around the geographic coordinates of each sampling site. Within these buffers, Land Use and Land Cover (LULC) metrics (such as bare soil, built-up areas, and dense vegetation) were extracted using remote sensing data. 4. Demographic and Hydrological Data Integration: Local population estimates within the 5km buffers were extracted using WorldPop (2020) spatial datasets. Seasonal cumulative rainfall data (mm) corresponding to the sampling periods were retrieved via Google Earth Engine (GEE) using satellite-derived meteorological datasets. 5. Data Compilation: All field readings, laboratory results, and spatial metrics were compiled, cleaned, and organized into the Excel workbook provided in this repository, structured for variance partitioning and multivariate statistical modeling.
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Funders
- Government of MalawiGrant ID: SFAD-WM Project Code: P-MW-AFF-003