The influence of fish culture in floating net cages on microbial indicators of water quality

Abstract

This work was carried out to analyse the microbiological parameters of the water quality of a reservoir used for the irrigation and culture of tilapia (Oreochromis niloticus) in floating net cages. The physico-chemical parameters, counts of mesophilic total aerobic bacteria, total and thermotolerant coliforms and fecal streptococci, and the presence of Escherichia coli in samples of water collected in three sites of the reservoir (pre-culture site, culture site, post-culture site) were analysed. The levels of ammonia (0.047-0.059 mg/L), nitrite (0.001-0.021 mg/L) and total phosphorus (0.050-0.355 mg/L) in the water did not show significant differences (p > 0.05) between sampling sites. The levels of total bacteria in the water varied between 1.3 x 10 4 and 67.3 x 10 4 CFU/100 mL. The MPN values of thermotolerant coliforms (< 930 MPN/100 mL) were within values recommended for water used for fish culture and/or irrigation. The presence of E. coli and fecal streptococci were verified in 48% and 56% of analysed samples, respectively. The site with floating net cages showed more samples contaminated with E. coli and fecal streptococci than other sampling points.Keywords: fish culture, tilapia, cage, coliforms, faecal streptococci. Influência da piscicultura em tanques-rede sobre os microrganismos indicadores da qualidade de água ResumoEste trabalho foi realizado para analisar os parâmetros microbiológicos da qualidade da água de um reservatório destinado a irrigação e à cultivo de tilapia do Nilo (Oreochromis niloticus) em tanques redes. Foi realizada análise de parâmetros físico-químicos, quantificação de bactérias totais aeróbias mesófilas, coliformes totais e termotolerantes, estreptococos fecais e a detecção de E. coli em amostras de água coletada em três pontos distintos do açude (pré-cultivo, cultivo, pós-cultivo). Os níveis de amônia (0,047-0,059 mg/L), nitrito (0,001-0,021 mg/L) e fósforo total (0,050-0,355 mg/L) na água não apresentaram diferenças significativas (p > 0.05) entre os pontos de coleta. As contagens de bactérias aeróbias mesófilas variaram entre 1,3 x 10 4 e 67,3 x 10 4 UFC/100 mL nas amostras de água. O NMP de coliformes termotolerantes (< 930 NMP/100 mL) se apresentou dentro do limite permitido para águas doces destinadas a piscicultura e/ou irrigação. A presença de E. coli foi constatada em 48% e de estreptococos fecais em 56% das amostras de água analisadas. O local de cultivo de tilápia em tanques-rede apresentou maior número de amostras contaminadas com E. coli e estreptococos fecais que outros pontos de amostragem.

Nitrogen and phosphorus flux from the production of Nile tilapia through the application of environmental indicators

“…However, as in any other activity directed to agricultural production, if not well managed, it can cause environmental damage (Gorlach-Lira et al, 2013;FAO, 2014). In search of sustainable aquaculture, it is necessary to consider the production, social development and environment al protection (Valenti, 2000).…”

Recent update on the prevalence ofVibriospecies among cultured grouper in Peninsular Malaysia

“…Result showed that the floating net cages had significantly ( p < 0.05) higher number of Vibrio isolates compared with the hatchery. There were several factors involved in increasing of bacteria density at the floating net cages such as large stocking density of fish, uncontrolled water quality and surrounding activities that cause pollution to water environment (Gorlach‐Lira, Pacheco, Carvalho, Melo Júnior, & Crispim, ; Lin, Jing, Lee, Chang, & Sui, ).…”

The Development of Marine Spatial Planning and Its Application for Floating Fish Net Culture

“…The intensive floating fish net culture can lead to the eutrophication of water bodies and to the emergence of deleterious effects on the water | 49 quality, such as the blooms of toxic cyanobacteria harmful for wildlife and humans (Gorlach-Lira et al, 2013). There are several works on the effect of fish culture in cages on water quality (see Jahani et al, 2012;Mente et al, 2006;Ntengwe & Edema, 2008;Price et al, 2015;Price & Morris Jr, 2013;Schenone, Vackova, & Cirelli, 2011;Wu, 1995;Yin, Harrison, & Black, 2008).…”

“…This fact indicates the opportunity of floating fish net culture to improve the national product of high economic species such as groupers, snappers etc. However, the floating fish net culture deals with several problems, such as seedlings, capital, infrastructure, technological aspect, deleterious effects on the water quality and lack of integrated spatial planning of the coastal area (De Silva & Phillips, 2007;Gorlach-Lira et al, 2013). Hence, marine spatial planning model should be beforehand used to determine the location of the floating fish net culture and its impact to the environment.…”