Seasonal study on the Cd, Se, and Zn uptake by natural coastal phytoplankton assemblages

Abstract

We conducted a seasonal study of the uptake of Cd, Se(IV), and Zn by natural phytoplankton assemblages collected from two locations in Hong Kong coastal waters. Marine phytoplankton in Port Shelter was dominated by diatoms and cyanobacteria, while phytoplankton in Tolo Harbour was dominated by dinoflagellates. The natural phytoplankton assemblages were spiked with macronutrients (N and P) and metals, and the accumulation of these metals was followed for 3 to 5 d in the laboratory. The two coastal systems were mostly P limited, with N limitation observed only during the summer in Tolo Harbour. With the additions of these macronutrients, phytoplankton responded in different ways in their accumulation of trace metals. Cadmium concentrations (normalized to chlorophyll a [chl a] concentration) increased by 25 to 38% with the simultaneous addition of N and P but were roughly constant when N alone was added. In N-limited systems, the Cd concentration increased by 25% with N addition. Concentrations of Se were reduced competitively (by 40-45%) with P addition. Zinc concentrations were reduced by 23 to 38% when both N and P were added, largely because of a major increase in biomass (biodilution). Both Cd and Zn uptake rates increased with increasing growth rates. The uptake rate of Se was not related to the growth rate because of the confounding influence of P addition. The particle concentration effect was observed only for Zn, in which the increasing chl a concentration biodiluted the Zn concentration in the phytoplankton. Overall, our results suggest that macronutrients may affect trace metal accumulation in natural phytoplankton because of their controls on cell growth, which may have implications for our understanding of trace metal dynamics in coastal ecosystems during phytoplankton blooms as well as for the prediction of trophic transfer in food chains.

Contrasting biogeochemistry of six trace metals during the rise and decay of a spring phytoplankton bloom in San Francisco Bay

“…Mesocosm studies have confirmed those findings by adding nutrients to stimulate a bloom under controlled conditions. For example, Riedel and Sanders (2003) found that dissolved Zn was depleted in mesocosm studies with Patuxent River water, and Wang et al (2005) showed that phytoplankton accumulated Zn from Hong Kong coastal waters. The contrasting results in our study could be because (1) sampling started too late to capture a Zn drawdown, (2) Zn was rapidly repartitioned from the particulate phase, (3) organic complexation limited Zn bioavailability, or (4) a combination of these factors.…”

“…Along with nutrients, trace metals have also been depleted by blooms in South Bay , the Scheldt estuary (Zwolsman and van Eck 1999), coastal waters (Schoemann et al 1998;Ingri et al 2004), and laboratory mesocosm studies (Beck et al 2002;Riedel and Sanders 2003;Wang et al 2005). In South Bay, the 1994 spring bloom depleted dissolved Cd, Ni, and Zn (but not Cu) from the water .…”

“…However, the number of such studies is limited by both the difficulty of capturing a bloom in the field and attributing any observed changes in metal concentrations to bloom processes . Because of these difficulties, some researchers have used mesocosm studies (Beck et al 2002;Riedel and Sanders 2003;Wang et al 2005) or large field enclosures (Muller et al 2005) to study the effect of phytoplankton blooms on metal concentrations.…”

Lead Biosorption by a Bacterium Isolated From Industrial Effluents

“…Tolerance and removal of toxic metal ions have been studied in bacteria [14][15][16][17][18][19][20], cyanobacteria [21,22], algae [23][24][25][26] and fungi [27][28][29]. Eccles, [30] has opined that the microbiological detoxification of polluted water is economical, safe and sustainable.…”

Do the levels of industrial pollutants influence the distribution and abundance of dinoflagellate cysts in the recently-deposited sediment of a Mediterranean coastal ecosystem?

“…Chemical contaminants can affect negatively the metabolic activities of vegetative cells of various phytoplankton species, inhibiting their growth and survival at determined concentrations (e.g., Rai et al, 1998;Mosulén et al, 2003;Wang et al, 2005;Miao and Wang, 2006;Herzi et al, 2013). Until now, most of the ecotoxicological studies conducted on dinoflagellates investigated the effects of contaminants only on vegetative cells.…”