Plankton distribution and abundance in the Sundays River estuary, South Africa, with comments on potential feeding interactions

Zooplankton of the St. Lucia Estuary during the current drought cycle: a comparison between open- and closed-mouth conditions

“…The main sample was then stirred vigorously so that all the organisms remained in a homogenous suspension. A 20 ml plastic vial attached to a metal rod was then used to withdraw 3 to 6 subsamples from mid-depth (Perissinotto & Wooldridge 1989, Jerling & Wooldridge 1995. Zooplankton within the samples were identified and counted with a dissecting microscope (400 ×).…”

Response of the Plankton to a Fresh Water Pulse in a Fresh Water Deprived, Permanently Open South African Estuary

“…Shifts in the total zooplankton abundances and biomass within southern African estuaries and indeed estuaries 412 worldwide, have been reported to be related to the interactive effects of temperature and food availability [2,5,17] The influence of temperature can largely be discounted as water temperatures were broadly similar during the two seasons The significant increase in zooplankton density and biomass recorded from dry to wet season during this study is, therefore, likely to be the result of elevated food availability. While the dry season biomass and densities values are in the range reported for Kariega Estuary, the wet season densities and biomass are substantially higher and are in the range reported for permanently open southern African estuaries with sustained freshwater inflow [2][3][4]13].…”

“…Successional patterns of copepods within southern African estuaries are largely driven by alterations in salinity [2]. Acartia longipatella reportedly attains the highest abundances and biomass during periods when oligohaline conditions prevail [2,5,21]. Conversely, the calanoid copepod, P. hessei can be considered as a pioneer species able to tolerate a high variance in salinity and temperature [2,21,22].…”

“…Reduced freshwater inflow into estuaries has been linked to a decrease in the phytoplankton size composition and daily production rates largely because freshwater inflow represents the primary source of nutrients necessary to sustain the growth of the phytoplankton, particularly diatoms [1,3,4]. Among the heterotrophic components of the estuarine food web, the alteration in the riverine inflow into estuaries has been linked to changes in the recruitment, biomass and species composition and distribution of both inverstebrates and vertebrates within these systems [2,5,6]. The formation of horizontal salinity gradients in estuaries is also associated with spatial patterns in the plankton biomass (so-called river-estuary interface (REI) zone [7] Finally, freshwater inflow into estuaries has been linked an increased diversity of niches and food sources available to animals in these systems [8][9][10].…”

Lake St Lucia, Africa’s largest estuarine lake in crisis: Combined effects of mouth closure, low levels and hypersalinity

“…In the laboratory a sub-sampling method 8 was used to analyse zooplankton samples. Taxa were identified and counted in a Bogorov tray (constructed in the Science Faculty Workshop, University of Zululand) using a stereo dissecting microscope (Leica MZ6, Tokyo, Japan).…”