Background:

Illegal open pit mining is one of the activities that most affects water ecosystems in Colombia and the Chocó (Jigualito, Condoto), generating physical and chemical changes that are still unknown.

Goals:

To evaluate the physicochemical behavior of the disturbance and the response of the peripheral fraction in water sources affected by mining.

Methods:

In situ measurements of physicochemical variables and determination of the richness, diversity and density of perifitic algae were made in three water sources with different temporality of mining cessation (current mining, 5-10 and 30 years) and a reference source.

Results:

Mining has a marked effect on the concentration of nutrients, suspended solid material and temperature, presenting a reduction pattern from current intervention scenarios to 30 years of abandonment. There were registered 120 species, 80 genera, 51 families, 34 orders and 13 divisions, predominating Frustulia romboides, Eunotia aff. minor, Ulothrix sp. and Frustulia sp1. Mining reduces more than 50% of the wealth (35) and diversity (1.5) of periphytic algae in relation to non-intervention scenarios (72, and 3.3, respectively) and although during the first 5 to 10 years of abandonment, a process of restoration (wealth 49, diversity 2.0), the effects of the disturbance are perceived after 30 years of mining cessation, where despite the increase in wealth (78), diversity does not reach the initial level (2.7).

Conclusions:

The recovery after mining exploitation is far-reaching, given the break in the stability of physical and chemical processes that produces activity in natural water systems.