Water Quality Variability and Flow Regimes Modulating Reproduction and Population Dynamics of Freshwater Fish

Abstract

Water quality deterioration and alteration of water regimes have become an emerging challenge for
freshwater ecosystems and are very important factors that affect the reproductive success of freshwater
fish communities. This study investigates the effect of fluctuation in water quality and modification
in the water flow regime on the reproduction and population dynamics of freshwater fish species in
certain rivers and lakes. The study is done through physicochemical characterization of the water
quality, analysis of hydrologic cycle water flow, and the reproductive capacity of the fish community
over a period of one year. Water quality parameters measured included dissolved oxygen, pH,
temperature, turbidity, ammonia, nitrate, and biochemical oxygen demand (BOD), while the flow
parameters measured included discharge rate and seasonal variability. Gonadosomatic index (GSI),
fecundity, egg viability, and larval survival rates were used to assess reproductive success, while catch
per unit effort (CPUE), species abundance, and recruitment pattern were used to evaluate population
dynamics. The results showed good statistical correlations for fish reproductive performance with
environmental conditions. Larval survival had a strong positive correlation with dissolved oxygen
(