Effect of tannins on survival and development of Daphnia menucoensis and the abundances of bacteria

Abstract

Polyphenols -products of organic-matter decomposition entering water bodies from autochthonous and especially allochthonous sources -affect primary producers, bacterioplankton, and zooplankton to consequently modify food webs. Cladocerans are widely used in research experiments because they constitute the most frequent prey of high-trophic-level organisms in the majority of lakes, and certain species symbolise the ecologic prototype of the generalist filter feeder. In our study area's shallow lakes, cladocerans, though generally of low abundance, do attain significantly high biomasses. We accordingly evaluated the mortality of the cladoceran Daphnia menucoensis Paggi, 1996 exposed to different tannin concentrations along with the bacterial abundance. In two experiments D. menucoensis females exposed to high tannin concentrations reproduced inefficiently, exhibited high mortality, and manifested altered behaviour, such as reduced reflexes and diminished mobility. Though tannins apparently affected algal abundances, the cladoceran herbivory strongly reduced those numbers. Positive effects on bacteria, however, were not recorded. High-allochthonous-organic-mattercontaining water bodies support trophic webs because bacterioplankton provide an alternative energetic base for the zooplankton, as possibly occurs in shallow lakes of the SaladoRiver basin, characterised by cyclic hydrologic periods alternating between draught and flooding and intensive land use. In conclusion, tannins diminish D. menucoensis's survival, locomotion, and the capacity to respond to stimuli. ARTICLE HISTORY

Strategic population responses of Daphnia spinulata Birabén, 1917 to salinity changes through laboratory bioassays

“…They may be found in highly fluctuating environments, such as ponds, marshes and shallow coastal lagoons (Dodson et al, 2009; Santangelo et al, 2008), thus constituting an informative model or research on the response to environmental stress. Because of these characteristics, among the more than 700 species of Cladocera (Smirnov, 2017), certain members of the genus Daphnia have received special attention (Sarma et al, 2005) because they are considered ecologic models for the generalist filter feeders and have been used to evaluate how stressful agents modify features of their life history (Alvarez et al, 2016; Euent et al, 2008; Lampert, 1997; Steinberg et al, 2010).…”

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