Diatom-based water quality assessment in streams influence by urban pollution: effects of natural and two selected artificial substrates, São Carlos-SP, Brazil

Abstract

Braz. J. Aquat. Sci. Technol. 15(1): 54-63. ISSN 1983-9057. Diatoms are good indicators of water quality in lotic systems. The purpose of this study was to provide information about the effects of natural and artificial substrates on diatom-based water quality assessment. Two artificial substrates (bricks and glass) were placed at 6 sampling sites and left for a month during summer base-flow period (2008). Water quality variables were measured at the beginning and end of the experiment. The IndVal method was used to find indicator species and species assemblages characterizing the three substrates. Species richness, diversity and equitability differed among sampling sites, tending to be higher in relatively unpolluted compared to polluted sites. The relatively less polluted upstream sites were characterized by such species as Aulacoseira ambigua, Aulacoseira granulata, Cymbopleura naviculiformis, Eunotia bilunaris, Fragilaria capucina and Gomphonema angustatum. On the other hand, the highly polluted downstream sites were characterized by Gomphonema parvulum, Nitzschia palea, Pinnularia amazonica and Synedra ulna. Species diversity and richness differed between the substrates, tending to be high on natural compared artificial substrate. Indicator species analysis showed that common diatom species were not restricted to single substrate. However, some species tended to prefer certain substrates as suggested by their highest indicator values in these preferred substrates. Specificity was generally high for natural compared to artificial substrates. Among the artificial substrates, more species tended to prefer glasses compared to bricks. Pollution tolerant species, N. palea, G. parvulum and Achnanthidium minutissimum, were highly associated with artificial substrates. Substrate differences may affect the interpretation of water quality results because the absence of a particular species on a given site is can be mistaken for the effects of the perturbations under study. The use of natural substrate is recommended compared to artificial substrate given the advantages of the former compared to the latter.

A re-examination of the type material of Entomoneis paludosa (W Smith) Reimer and its morphology and distribution in African waters

“…The relationship between diatoms and pH is strong, as pH exerts a direct physiological stress on diatoms and influences other water chemistry variables such as resistivity and conductivity (Bere & TunDiSi 2011). Changes in the pH and resistivity levels might have had a physiological effect on the species, thereby affecting their abundances across the study months.…”

Colonisation and community structure of benthic diatoms on artificial substrates following a major flood event: A case of the Kowie River (Eastern Cape, South Africa)

“…At each study site, 18 tiles were placed vertically in 6 tile structures (30 × 18 cm) punctured with regular holes to allow the free flow of water around the tiles (Fig. 3), as per Peterson (1983), Lane et al (2003) and Bere and Tundisi (2011). Each structure was anchored in the stream using a rope tied to the nearest tree in the riparian zone.…”

“…The affinities of diatoms to various cations have not been sufficiently investigated or demonstrated, but are likely to be linked to physiological mechanisms (Bere et al, 2013). The pH level can exert a direct physiological stress on diatoms and also strongly influences other water chemistry variables such as resistivity and conductivity (Bere and Tundisi, 2011). The pH values at the upstream site were largely alkaline (6.4-8.9), while at the downstream site they were circumneutral; thus most of the species were either alkaliphilic or circumneutral-tolerant.…”

Phytoplankton diversity and abundance in water bodies as affected by anthropogenic activities within the Buea municipality, Cameroon

“…Microscopic analyses of water samples provide information on the diversity and density of algal species which could potentially be useful as early warning signs of deteriorating conditions . The use of algae as aquatic environmental indicators has long been documented (Battarbee et al, 1986;Michelutti et al, 2001;Simboura and Zenetos, 2002;Muriel et al, 2004;Smol and Stoermer, 2010;Oberholster et al, 2010;Jafari and Alavi, 2010;Bere and Tundsi, 2011). Palmer (1969) published a list of algae tolerant to organic pollution in water environments.…”