Influence of environmental changes on picophytoplankton and bacteria in Daya Bay, South China Sea

Abstract

Environmental changes driven by intense human disturbance and natural processes govern the abundance and distribution characteristics of two picophytoplankton groups (Synechococcus and picoeukaryotes). Picophytoplancton and high DNA (HDNA) and low DNA (LDNA) bacterial groups, identified by flow cytometry, were assessed during the autumn monsoon transition period in Daya Bay (South China Sea). The abundance of Synechococcus and picoeukaryotes ranged from 2.16 × 104 to 1.45 × 105 cell mL–1 and from 0.78 × 103 to 7.95 × 103 cell mL–1, respectively. The abundance of HDNA bacteria in surface water (mean: 5.58 × 105 cell mL–1) was greater than in bottom water (mean: 3.74 × 105 cell mL–1), with significant difference (n = 12, P = 0.05). The difference in LDNA abundances between surface (mean: 7.06 × 105 cell mL–1) and bottom (mean: 4.83 × 105 cell mL–1) waters was insignificant (n = 12, P > 0.05). The results of the principal component analysis showed that both picophytoplankton (Synechococcus and picoeukaryotes) and bacteria (HDNA and LDNA) were positively related to nutrients (NO3-N, NH4-N, and SiO3-Si). Three subsystems in the bay were identified as follows: the west and east parts, the central and northwest parts, and the mouth and central part.

Spatiotemporal distribution of the bacterial contamination of agricultural and domestic wastewater discharged to a drainage ditch (Sinaloa, Mexico)

“…As in our research, Cheng et al (2013) found a negative correlation between the levels of dissolved oxygen and the density of E. coli; wetland aeration favored the development of E. coli predators and promoted the photooxidative damage. In Daya Bay (China), the presence of bacteria and microalgae were mainly associated with the concentration of nutrients (nitrates, ammonia, and silicates), which are highly impacted by anthropogenic activities, whereas dissolved oxygen showed a lower correlation (Wu et al 2014). In regard to pH, the values obtained for the samples from all the SS comply with the guidelines given in NOM-001-ECOL-1996 (pH = 5-10), which establishes the permissible maximum limits of pollutants in wastewater discharges in national waters.…”

“…Las principales actividades económicas de Sinaloa dependen de abundates recursos hídricos y de la calidad del agua (CONAPESCA 2012). Hoy en día se conoce que el agua contaminada de los canales de drenaje agrícola afecta de manera negativa la vida acuática y terrestre en Sinaloa (Escobedo-Urías et al 1999, Haws et al 2006, Ochoa Izaguirre y Soto-Jiménez 2013), México y el mundo (Bagordo et al 2012, Matano et al 2013, Riera et al 2013, Valdés et al 2014, Wu et al 2014. Por otra parte, los canales de drenaje pueden funcionar como humedales artificiales de flujo superficial y disminuir la contaminación del agua y sus efectos negativos, pero éstos deben transportar bajos flujos de agua para favorecer el establecimiento de las plantas acuáticas (Kadlec y Wallace 2009).…”

“…Fecal coliforms, found in the intestine and feces of animals, are indicators of pollution and consequently of water quality, and thus warn about the possible presence of human pathogens. The presence of fecal coliforms in aquatic environments may be due to the abundant incorporation of water contaminated by sewage and other organic wastes from anthropogenic activities (Cupul-Magaña et al 2006, Bagordo et al 2012, Sidhu et al 2012, Barrera-Escorcia et al 2013, Ochoa-Izaguirre and Soto-Jiménez 2013, Valdés et al 2014, Wu et al 2014.…”

“…Las bacterias coliformes fecales, encontradas en el intestino y heces de animales, son indicadores de contaminación y consecuentemente de la calidad del agua, y advierten así sobre la posible presencia de organismos patógenos que pueden afectar la salud humana. Su presencia en ambientes acuáticos puede deberse a la incorporación abundante de aguas contaminadas con excretas y otros desechos orgánicos derivados de actividades antropogénicas (Cupul-Magaña et al 2006, Bagordo et al 2012, Sidhu et al 2012, Barrera-Escorcia et al 2013, Ochoa Izaguirre y Soto-Jiménez 2013, Valdés et al 2014, Wu et al 2014.…”

“…Hence, the main economic activities of Sinaloa depend on sufficient water resources and good water quality (CONAPESCA 2012). It is now known that contaminated agricultural drainage water adversely affects aquatic and terrestrial life in Sinaloa (Escobedo-Urías et al 1999, Haws et al 2006, Ochoa-Izaguirre and Soto-Jiménez 2013, in Mexico, and around the world (Bagordo et al 2012, Matano et al 2013, Riera et al 2013, Valdés et al 2014, Wu et al 2014). On the other hand, agricultural drains can function as artificial surface wetlands and reduce water pollution and its adverse effects, but the drainage flow must be low permitting the presence of aquatic plants (Kadlec and Wallace 2009).…”