Physical and Chemical scenario
All rock pools were classified as shallow (≤ 5 m), with warm and mixed waters (≤ 36.7 Co) and low light availability (Zeu : Zmix ≤ 1) was observed. The pH values ranged from acidic to slightly alkaline (≤ 10.2) (Table 1).
We identified 55 species and morph species; the highest biomass from the phytoplankton community was associated with Microcystis sp. in rock pools I (maximum 22.8 mg.L-1), II (maximum 269.5 mg.L-1) and VII (maximum 2366.2 mg.L-1) (Table 1). In the absence of Microcystis sp., Chlorococcales were dominant (XV and XIII). Submerged macrophytes (Chara martiana J. Wallman) were only found in VIII and IX, which coincided with the highest values of Z eu : Z mix(≤ 1) (Figure 2).
Traditional knowledge and Rock pool use
For many decades, the Rio Direito community has been witnessing a series of changes since rock pools were introduced. One of the most important historical events occurred when emergency rock pools were constructed, which elderly people reported as a project created and maintained by the government.
Besides the construction of these ecosystems, other ecosystems emerged that received specific names, as reported by some informants.
The deepest Lagoa da Cobra;
As well as Lagoa da Batata,
Lagoa da Mucunã, Baixa detrás da lagoa, Piscina, Lagoa Velha,
Tanque de Severino Tito, Tanque Inácio Roberto,
Cortume de Maria Simão, Baixa do Anel, Tanque Baixa de Rita,
Baixa de Tia Francisca, Tanque de Santo Moura, Baixa de Alexandrina,
Loca de Lotero, Baixa escondida, Tanque do Pereiro, Tanque da Caubêira,
Tanque dos Nêgro. (R,M.F, 81)
Here we have twenty rock pools, some big,
others not, some are very shallow and will dry up soon,
the deepest ones last longer...
(R. F, 48)
Among the management techniques to reduce water evaporation, residents reported the use of wood (so-called stake) and stones. The main objective was to prevent animals, leaves, and twigs from entering the rock pools, favoring increased water quality (Figure 3). Most people understood water quality concepts well and how to correctly apply them (Table 2), specifically about watercolor. One common association was low water quality with green colored rock pools. In general, the green color was correlated to cyanobacteria blooms (Table 1). Overall, the residents did not recognize floral diversity, calling all species (or biological groups) sludge or paste.
In the present study, cisterns were more commonly used than rock pools. Thus, some informants reported cisterns as the best water storage method:
“In cisterns the water is cleaner than in rock pools” (J.C.F, 44).
According to informants, the use and management of rock pools were reduced after the implementation of the governmental programs, among these the P1MC (One Million Cisterns Project). The quality of life of inhabitants in the Rio Direito has improved, and rock pools have been forgotten about by most of its inhabitants and those from neighboring locations, remaining for domestic uses such as laundry and consumption (Table 3). Regarding the water used, over time water has been used for domestic activities, farming and livestock and human supply. The farmers had their own perspective about water quality, including sweet taste and transparency, i.e., more transparent, and sweeter water is better. The relationship between cleaning rock pools and water quality was unanimous.
“How can a rock pool be found?"
The residents used certain parameters to find rock pools, among which included the presence of soil between the rocks, rock quality (hard and mid-hard rocks), and if rocks were continuous, shattered or presented fissures. Over time, the people have tested and enhanced this perception. In specific cases, these rock pools received human adaptations, e.g., wall built with cement or concrete. Most informants reported that they did not know the origin of the water bodies, whereas others claimed it was “nature's blessing”.