The contribution of volunteer-based monitoring data to the assessment of harmful phytoplankton blooms in Brazilian urban streams.
Urban streams are vulnerable to a range of impacts, leading to the impairment of ecosystem services. However, studies on phytoplankton growth in tropical lotic systems are still limited. Citizen science approaches use trained volunteers to collect environmental data. We combined data on urban streams collected by volunteers with data obtained by professional scientists to identify potential drivers of phytoplankton community and determine thresholds for Cyanobacteria development. We combined datasets (n=117) on water quality and environmental observations in 64 Brazilian urban streams with paired data on phytoplankton. Sampling activities encompassed dry (July 2013 and July 2015) and warm (February and November 2014) seasons. Volunteers quantified phosphate (PO43-), nitrate (NO3-) and turbidity in each stream using colorimetric and optical methods and recorded environmental conditions in the immediate surroundings of the sites through visual observations. We used non-parametric statistics to identify correlations among nutrients, turbidity and phytoplankton. We also looked for thresholds with respect to high Cyanobacteria abundance (>50,000cells/mL). The streams were characterized by relatively high nutrient concentrations (PO43-: 0.11mg/L; NO3-: 2.6mg/L) and turbidity (49 NTU). Phytoplankton densities reached 189,000cells/mL, mainly potentially toxic Cyanobacteria species. Moderate but significant (p<0.05) correlations were observed between phytoplankton density and turbidity (ρ=0.338, Spearman) and PO43-(ρ=0.292), but not with NO3-. Other important variables (river flow, temperature and light) were not assessed. Volunteers' observations covaried with phytoplankton density (p<0.05, Kruskal-Wallis), positively with increasing number of pollution sources and negatively with presence of vegetation in the riparian zone. Our results indicate that thresholds for PO43-(0.11mg/L) can be used to separate systems with high Cyanobacteria density. The number of pollution sources provided a good indicator of waterbodies with potential cyanobacteria problems. Our findings reinforced the need for nutrient abatement and restoration of local streams and highlighted the benefits of volunteer-based monitoring to support decision-making.
Departamento de Hidráulica e Saneamento, Escola de Engenharia de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-Carlense, 400, CEP 13566-590 São Carlos, SP, Brazil. Electronic address: davig@sc.usp.br.
Davi Gasparini Fernandes
DGF
Cunha
Departamento de Hidráulica e Saneamento, Escola de Engenharia de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-Carlense, 400, CEP 13566-590 São Carlos, SP, Brazil.
Simone Pereira
SP
Casali
Departamento de Ciências Ambientais, Universidade Federal de São Carlos, Rodovia Washington Luiz, km 235, CEP 13565-905, São Carlos, SP, Brazil.
Patrícia Bortoletto
PB
de Falco
Earthwatch Institute, Mayfield House, 256 Banbury Rd, Oxford OX2 7DE, United Kingdom.
Ian
I
Thornhill
Earthwatch Institute, Mayfield House, 256 Banbury Rd, Oxford OX2 7DE, United Kingdom.
Steven Arthur
SA
Loiselle
D001938:Brazil; D002947:Cities; D003256:Community Participation; D000458:Cyanobacteria / Q000254:growth & development / Q000302:isolation & purification; D004784:Environmental Monitoring / Q000379:methods*; D005068:Eutrophication; D005618:Fresh Water; D006801:Humans; D010839:Phytoplankton / Q000254:growth & development* / Q000302:isolation & purification; D045483:Rivers; D012621:Seasons; D014838:Volunteers
Citizen science; Cyanobacteria; Eutrophication; Nutrients; Urban water bodies