Kling H.J.,Algal Taxonomy and Ecology Inc |
Watson S.B.,Environment Canada |
Mccullough G.K.,University of Manitoba |
Stainton M.P.,Northwest Atlantic Fisheries Center
Aquatic Ecosystem Health and Management | Year: 2011
Over the past 40 years, hydroelectric, agricultural and urban watershed development and changing hydrology have transformed Lake Winnipeg into a highly eutrophic reservoir with annual outbreaks of widespread surface algal blooms, shoreline and net fouling, and concerns with intermittent cyanotoxin production. To provide a better understanding of the magnitude of these changes and the major causes, we examine long-term increases in phytoplankton biomass and shifts in phytoplankton species dominance in the context of both in-lake and watershed processes. We compare phytoplankton and water quality data from early (1969) and recent (1994-2007) lake-wide surveys, and information from paleolimnological analysis of sediment cores and satellite remote sensing. Our results demonstrate a recent and dramatic rise in severe algal blooms and increased dominance of cyanobacteria beginning in the mid-1990s, coincident with a large increase in phosphorous loading to the lake. Distinct increases in sediment core accumulation of nutrients and chlorophyll, cyanobacteria and diatom microfossils coincided with hydroelectric and agricultural development, increased Red R discharge and shifts in water transparency patterns across the lake. There has been a dramatic increase in phytoplankton biomass, accompanied by marked shifts in seasonal community composition. Spring diatoms blooms are of shorter duration and increasingly dominated by more eutrophic diatom taxa while summer blooms show reduced taxonomic diversity and an increased predominance of nitrogen-fixing cyanobacteria. Satellite images showed annual development of vast summer surface blooms, mainly in the north basin, with chlorophyll highest in regions of relatively low suspended sediment concentration and high transparency. There is an increasing dominance of potentially toxic cyanobacteria taxa and high levels of microcystins in nearshore samples of surface blooms. The combined effects of nutrient increases, algal species shifts and toxin production represent a potential threat to the sustainability of ecosystem function and productivity. © 2011 Crown copyright.
Zhang W.,Environment Canada |
Zhang W.,University of Toronto |
Watson S.B.,Environment Canada |
Rao Y.R.,Environment Canada |
Kling H.J.,Algal Taxonomy and Ecology Inc.
Ecological Modelling | Year: 2013
This paper describes a simple modelling framework to predict water quality and algal biomass in large, complex lakes with insufficient and often multifarious data and challenging logistics. We applied a linked model design to Lake of the Woods (LOW) as a case study, using output from hydrodynamic, mass balance and empirical models to predict spatial differences in nutrients (total phosphorus (TP)), and algal and cyanobacterial standing stock (chlorophyll-. a (chl. a), biovolume-derived biomass and cyanobacterial dominance). Our models reproduced observed temporal and spatial distribution of TP and chl. a well. The central and south segments behaved like shallow lakes with strong variability in TP and phytoplankton biomass, whereas two relatively isolated and deeper segments in the north were characterized with less variability in TP and lower phytoplankton biomass. Algal biomass and cyanobacterial dominance were best predicted in the more eutrophic southern sectors; however the fit was strongly dependent on the source of biomass data. The results reinforce the need to apply a multi segmental model to these systems which cannot be effectively modelled using a single box approach because of spatial differences in hydrodynamics and topography. © 2013.
Orihel D.M.,University of Alberta |
Bird D.F.,University of Quebec at Montréal |
Brylinsky M.,Acadia University |
Chen H.,Shenzhen University |
And 13 more authors.
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2012
Although the cyanobacterial toxin microcystin has been detected in Canadian fresh waters, little is known about its prevalence on a national scale. Here, we report for the first time on microcystin in 246 water bodies across Canada based on 3474 analyses. Over the last 10 years, microcystins were detected in every province, often exceeding maximum guidelines for potable and recreational water quality. Microcystins were virtually absent from unproductive systems and were increasingly common in nutrient-rich waters. The probable risk of microcystin concentrations exceeding water quality guidelines was greatest when the ratio of nitrogen (N) to phosphorus (P) was low and rapidly decreased at higher N:P ratios. Maximum concentrations of microcystins occurred in hypereutrophic lakes at mass ratios of N:P below 23. Our models may prove to be useful screening tools for identifying potentially toxic "hotspots" or "hot times" of unacceptable microcystin levels. A future scientific challenge will be to determine whether there is any causal link between N:P ratios and microcystin concentrations, as this may have important implications for the management of eutrophied lakes and reservoirs.
Kling H.J.,Algal Taxonomy and Ecology Inc |
Dail Laughinghouse H.,University of Maryland University College |
Dail Laughinghouse H.,Smithsonian Institution |
Smarda J.,Masaryk University |
And 5 more authors.
Fottea | Year: 2012
A new morphotype of the genus Pseudanabaena (Cyanoprokaryota, Oscillatoriales) was identified from bloom samples of Aphanizomenon flos-aquae Ralfs ex Bornet et Flahault taken from large central North American water bodies, Lake Winnipeg (LWPG) and Lake of the Woods (LOW), which drains into Lake Winnipeg (Fig. 1) and a strain of this morphotype was isolated from LOW in the fall of 2009. Here we describe the morphology and basic ecology, cytology and phylogenetic position of this new chromatic adaptive and colony forming planktonic species and propose a new species Pseudanabaena rutilus-viridis Kling et al. Preliminary research has indicated that it has the ability to produce the toxin microcystin and further research is under way to assess its ability to produce taste-odour and other toxins and nitrogen-fixing capacity. © Czech Phycological Society (2012).
Strong spatial differentiation of N and P deficiency, primary productivity and community composition between Nyanza Gulf and Lake Victoria (Kenya, East Africa) and the implications for nutrient management
Gikuma-Njuru P.,South Eastern Kenya University |
Guildford S.J.,University of Minnesota |
Hecky R.E.,University of Minnesota |
Kling H.J.,Algal Taxonomy and Ecology Inc
Freshwater Biology | Year: 2013
Study of phytoplankton nutrient status, biomass, productivity and species composition was carried out between March 2005 and March 2006, along a transect between north-eastern open Lake Victoria and the large, shallow Nyanza Gulf in order to examine how the terrestrial run-off can influence phytoplankton community and nutrient status and determine whether nutrient management of catchment run-off has the potential to control the algal blooms in the gulf. Hydrological and nutrient differences between the open lake and the gulf create a transition from P deficiency for phytoplankton within the gulf to nitrogen deficiency in open lake. The shallow and turbid gulf was continuously dominated by non-nitrogen-fixing filamentous and chroococcale colonial cyanobacteria, but seasonal stratification and deeper mixing depth in the open lake favoured diazotrophic cyanobacteria and diatoms. Seston ratios and metabolic nutrient assays indicated the gulf to be sufficiently phosphorus deficient to impose P limitation on phytoplankton growth and biomass. In contrast, the open lake is not P deficient and is more likely to experience N deficiency that favours diazotrophic cyanobacteria. Because of high turbidity in the gulf, the euphotic zone is very shallow, limiting integral primary productivity compared to the less turbid open lake; high PAR extinction may also favour Microcystis blooms in the gulf. Increased P loading into the gulf may translate to higher algal biomass, mainly of the bloom-forming and potentially toxic cyanobacteria, and therefore, reduction in P loading into the gulf should be a management priority. However, a review of historical data indicates that the greatest change in water quality in the gulf is increased turbidity that reduces light availability and may limit algal growth more than P deficiency in years of high rainfall and river discharge. © 2013 John Wiley & Sons Ltd.