Blooms intensifying – or at least trying to

It appears that the notification for my last post wasn't sent out for some reason - hopefully this one makes it passed my computer.

Click on the image for a larger view.

Just a short note to share the most recent clear satellite image of the lake, dated August 16th. This image shows the blooms intensifying somewhat in both basins of the lake, and the narrows. Not surprising given the weather we have experienced lately. The north basin bloom seems to be staying predominantly along the clear/turbid water interface on the east side north of Berens River. Similarly, the south basin bloom appears to be trying to take hold at that interface as well. Any protected nearshore areas will also be susceptible to surface bloom formation. Also interesting is the intense erosion occurring along the north shore. Unfortunately, Two-Mile Channel is obscured by a small cloud, but you can still see how Playgreen Lake is impacted by the two outflows from Lake Winnipeg, the constructed Two-Mile Channel and the natural outflow at Warren's Landing. Reminder that the complete set of 2014 satellite images is in the image library above.  
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Long weekend forecast should please both humans and blue-greens alike

First post of the field season – and yes, a little late, I know. I have myself and zebra mussels to blame for that - another story, perhaps for another day. Despite my negligence in the writing part of the blog, I do tend to keep up with the imagery. So if the urge to view Lake Winnipeg from space strikes you at any time, simply visit the Image Gallery. If nothing else, check out the July 3 image - a veritable work of art. Below is an image from July 30th – unfortunately a bit hazy but still revealing. Noteworthy is an obvious surface bloom forming on the east side of the north basin (north of Berens Island). If these hot, relatively calm conditions persist, one would expect this bloom to get larger wherever the water clarity is sufficient to support photosynthesis. Also of note - if you zoom into the image, there are hints of surface algal growth in the narrows and south basin. Given the higher turbidity* in these areas, the weather will play a particularly important role in determining the extent to which these patches develop into blooms in the next little while. In the south basin of Lake Winnipeg, water clarity is generally the limiting factor for algal growth - lots of nutrients but not enough light. Calm conditions can result in clearer water (less turbid is perhaps more accurate for the south basin) because particles can settle out of the water column and there is less re-suspension of bottom sediments. Add some hot, sunny days to the mix and you may have the makings of a surface bloom, likely dominated by cyanobacteria (aka the infamous blue-greens), who like it hot but not turbulent. Last I checked, the long weekend forecast was hot and calm - this should please both humans and blue-greens alike. *Turbidity - suspended (inorganic) particles in the water have a tan colour in the image. The dark brown colour is due to dissolved organic carbon (DOC) - similar to a cup of tea - coloured but with no particles floating around. Many of the eastern rivers contain high levels of DOC - especially visible near the mouth of the Winnipeg River, albeit somewhat diffuse due to mixing with lake water.

July 30, 2014 - click on the image to enlarge.

There is a general tendency, especially by the Press, to describe algal blooms in Lake Winnipeg as toxic (among other unfortunate and inaccurate descriptors – don’t get me started…). Based on microcystin-LR data collected primarily by the Province of Manitoba over the last 10+ years, concentrations of this toxin are, to date, generally extremely low and rarely exceed the recreational water quality guideline. Unfortunately, you can’t tell if an algal bloom is producing toxins or not simply by looking at it. Thus, it is always preferable to not swim in or drink water from an algal bloom, pets included. Have a wonderful long weekend – and to those celebrating a birthday, Happy Birthday!
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Mushrooms, snakes and… algae

August 28 - click on the image for a larger view

I was hoping to post a clear image of the entire lake before the long weekend but the best I can do is from August 28. The north basin is largely obscured by cloud, although one can still see a surface bloom all along the eastern shore.  Another surface bloom is clearly visible in Fisher Bay, and perhaps of most interest to beach-goers is the bloom in the central south basin off Victoria Beach. Hedy Kling (Algal Taxonomy and Ecology Inc.) recently examined samples from this area and sent a few images for your viewing enjoyment (below). Samples were collected by Hannah, an enthusiastic soon-to-be grade 8 student who started her science fair project early this year! Based on these recent samples, Hedy found that cyanobacteria (aka blue-greens) currently comprise the algal community in the Victoria Beach area. More specifically, the bloom is dominated by Aphanizomenon flos-aquae complex, with three species of Microcystis and some Pseudanabaena* also present. Noteworthy is that all of them have the ability to produce toxins. I do not have any toxin data from this bloom to share; however, based on the Provincial dataset for microcystin-LR (an algal toxin), levels in Lake Winnipeg algal blooms are generally well below the recreational water quality guideline in inshore samples, and usually below detection in offshore samples. Nevertheless, just as one doesn’t snack on wild mushrooms during a casual walk in the forest, or play with unidentified snakes, one shouldn’t swim in a blue-green algal bloom – just in case… *Before I sign off to enjoy the long weekend, I would like to add that it was Hedy who first described Pseudanabeana rutilis-viridis as a new cyanobacterial species - and the samples were from, you guessed it, Lake Winnipeg. Click on her images below for a closer look.  

Aphanizomenon flos-aquae - sampled near Victoria Beach, August 13, 2013. Photo: Hedy Kling

 

Microcystis - sampled near Victoria Beach, August 13, 2013. Photo: Hedy Kling

 

Pseudanabeana rutilis-viridis - Traverse Bay. Photo: Hedy Kling

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Nutrients alone do not an algal bloom make

We have had some clear satellite imagery as of late. Below is the image from August 14th – the rest are in the Image Gallery. I encourage you to scroll through the collection to see the development of this summer’s blooms (after reading this post, of course.)

The satellite image below shows an extensive surface bloom in the north basin, confined largely to the area north of Sturgeon Bay and Berens River, but starting to extend south to Fisher Bay and Bloodvein. According to early results from Hedy Kling (Algal Taxonomy & Ecology Inc.), the composition of the north basin algal community varied spatially during the summer research survey. The bloom on the east side was dominated by cyanobacteria (aka blue-greens), notably Dolichospermum species (formerly Anabaena) with a low abundance of Aphanizomenon flos-aquae complex. The Dolichospermum also contained a lot of heterocysts (specialized structures that  allow the cells to carry out nitrogen fixation) indicating nitrogen limiting conditions in that area of the lake. Conversely,  there were few cyanobacteria on the western side near the Saskatchewan River, and instead the community was dominated by a number of different diatom species. Areas in the centre of the north basin had comparatively little algae at the time of sampling (late July) but this has since changed, based on the satellite imagery. It is anticipated that the composition of the north basin algal community will continue to change as the summer progresses, and it will likely become dominated by Aphanizomenon species - they like it hot. If you look closely, there is a small surface bloom in the south basin. Although insignificant compared to the north, the potential for this minor surface bloom to develop further is high for a number of reasons. The first is nutrients – needless to say, Lake Winnipeg generally has plenty of nutrients, which serve as food for algae. (I say “generally” because nutrients can be limiting in Lake Winnipeg, like nitrogen and silica – a topic for another post.) However, nutrients alone do not an algal bloom make – algae also need light. The darker patches in the south represent clear water, or at least clearer than the tan-coloured areas, which have more floating particles. Clear water allows greater light penetration, thus, it is in these darker (clearer) areas that one would expect the existing small blooms to continue growing. Lastly is the weather  - notably hot and calm - although today is windy, which will certainly stir things up quite a bit. Generally, good beach weather for us means good blooming weather for cyanobacteria. Calm conditions also allow the larger particulate material to settle out rendering the water clearer, which can further contribute to favourable bloom-forming conditions. Although persistent high winds and cooler weather could change the outlook, it appears that we currently have the key ingredients for the development of considerable cyanobacterial blooms in the south basin and continued development in the north.

August 14th - click on the image to enlarge

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‘Tis the season…

‘Tis the season for the development of cyanobacterial surface blooms on Lake Winnipeg (and many other lakes). Recent satellite images (yesterday’s image is below) show a persistent bloom near Reindeer Island on the west side of the north basin and a newer bloom on the east side from Berens Island northward to the outflow of the lake. Surface blooms in the south basin and narrows are not as obvious as in the north, although Washow Bay has had a notably visible bloom come and go over the last week. There is also a small bloom developing north of Fisher Bay, near Jackhead. Also of note - the south basin is becoming more turbid as the lake continues to mix – shown by the tan colour, which is due to suspended particles in the water column. These particles can block sunlight - one of the ingredients that algae need to grow – which is why the south basin generally has less extensive blooms than the north. Despite the promise of increasing turbidity, there are still areas of clear water (dark in colour) in both basins and the narrows - the makings are certainly there for a festive algal season. Reminder - I post satellite images more often than I blog. Please visit the Image Galleries tab above to view a more complete collection of images.

July 15, 2013 - click on the image for a larger view

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A stunning satellite image to start the season

I was going to start this season's blog with a comparison of images to show how late ice-out was this year compared to previous years. However, upon closer examination of the images from this spring (which are all in the satellite image gallery by the way), there appears to be something else that deserves mention. The satellite image below - absolutely stunning I might add - was taken on June 2, not long after the north basin became ice free. It shows a very heterogeneous lake, as is often the case at this time of year as the inflowing rivers mix and begin to influence the water clarity of the lake. What caught my eye (in addition to the amazing mixing that is taking place) was the apparent diatom bloom in the north, from about Dauphin Bay to the central north basin and outflow at Warren Landing. (Diatoms are a group of algae that are an important source of food for invertebrates, which in turn support higher organisms like the forage fish community.) This bloom appears to be quite extensive and persistent even after ice-out. The first evidence of this bloom was at the outflow in mid-May when the north basin was still frozen, which suggests that it started to form under the ice. Under ice diatom growth is not unusual especially in years when there is not much snow, thereby allowing light to penetrate through the ice and support photosynthesis. Early results from Hedy Kling (the authority on Lake Winnipeg algae) show this year's south basin algal community made up almost entirely of diatoms - primarily Aulacoseira icelandica - with some green algae (also a good source of food) - see Hedy's images below. North basin samples are being collected this week off the Namao so it will not be long before we know which species comprise the north basin bloom; Hedy is putting her money on A. icelandica. The ultimate fate of this bloom is important. The assumption of many, especially the media, is that if there is an algal bloom, it will decompose, use up oxygen, and suffocate the animals that live in the lake - hence the terms 'choking' and 'dying'. Low oxygen events have been measured in Lake Winnipeg, but very rarely and they do not persist, at least based on the data that we have - this is largely due to the fact that Lake Winnipeg is an extremely shallow and, therefore, well mixed system. A more likely fate, especially for spring diatoms, is being consumed by invertebrates such as zooplankton (small, floating animals) and benthos (the animals that live in the sediment at the bottom of the lake) since diatoms are an excellent source of food. Interestingly, the weather can also play a role in both the growth of algae and its fate - windy conditions can hamper the growth of surface blooms and effectively mix the lake, while warm, calm conditions can do the opposite. Updates on the bloom will follow - in the meantime, click on the images below for a larger view of this wonderfully dynamic and complex system.

June 2, 2013

Photo by Hedy Kling (Algal Taxonomy & Ecology Inc.)

Photo by Hedy Kling (Algal Taxonomy & Ecology Inc.)

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Blue-greens in the Red – getting ready for winter

It has been a long time since the last post. This is primarily due to the unusually cloudy conditions as of late - since October 1st, there was one lonely satellite image that was clear enough to download and process - it is in the 2012 archive if you wish to view it. (While there, check out the new 'Students' gallery.) All the while, the Science and Education Programs on the lake wrapped up for another  season, the research vessel Namao has been shut down for the winter, and ice is starting to form on the rivers and shallow bays. And we mustn't forget - the akinetes are forming!

Decaying algal cells on the bank of the Red River in Winnipeg. (R. Brynjolson)

In early November, I was contacted by local artist, Rhian Brynjolson, who was wondering about some blue-green algae along the banks of the Red River. Intrigued, I asked her to get a sample, which she somehow managed to do despite the waist deep mud. Algal taxonomist, Hedy Kling, kindly took a look at the sample and found a variety of blue-greens (cyanobacteria) including Aphanizomenon flos aqua (dominant in the sample but decaying), Microcystis (a rare occurrence), and Aphanocapsa holsatica. Hedy also noted an abundance of akinetes, or dormant/resting-state cells. She believes that a dying algal bloom came down either the Assiniboine or Red River and was well on its way to settling on the bottom of the river when the water levels went down (thereby revealing it to the passing artist). Perhaps most interesting is that if the akinetes survive the winter, they could provide the 'seed' for some of next year's blooms in the lake. Click on the images for a larger view.

Microcystis (H. Kling)

                 

Aphanizomenon flos aqua - decaying cells. (H. Kling)

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September 15th – clear skies reveal a not so clear lake

September 15

The persistent high winds over the last week appear to be mixing the lake quite effectively. Consequently, the water looks increasingly turbid in most areas of the lake. The plume of suspended clay originating from the north shore now extends further into the lake before exiting via Two-Mile Channel and Warren's Landing. It is difficult to see amidst the swirls of suspended sediment in the north, but there does appear to be a surface bloom near the north shore of Limestone Point and offshore in the central part of the basin. I suspect the higher turbidity will curtail further development of this bloom, with perhaps the exception of the area northeast of Grand Rapids where some clear water remains. In the south basin and narrows, small patches of surface blooms persist despite the winds, but generally, the water appears very turbid due to the suspended sediment. Thus, it is not likely that extensive new blooms will form under these conditions. (Click on the image for a closer look.)
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September 3rd – worth a closer look

September 3, 2012

At first glance, this image doesn't look like much but it's worth a closer look. I included Lake of the Woods because there appears to be a sizeable surface bloom there. The south basin of Lake Winnipeg is particularly interesting -- again, a considerable bloom is present, especially visible in the southern portion near the mouth of the Red River. In that area, you can also see clearer water along the southern edge of the bloom. The lake appears to be quite turbid northeast of Victoria Beach, and the Winnipeg River plume with its high dissolved organic carbon is also visible as it mixes with the turbid water in the bay. The narrows region is obscured by clouds, as is some of the north basin. Nevertheless, if you zoom in, it looks like a small bloom is present near Limestone Point -- given the clear water in the vicinity, this 'little' bloom could become a big one. There also seems to be a lot of clay being eroded from the north shore and making its way into Playgreen Lake. Overall, this image nicely illustrates how heterogeneous Lake Winnipeg can be.
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August 30th image

August 30, 2012

August 30, 2012. The south basin bloom appears to be further south now, nearer to the mouth of the Red River and the west side of the basin. Although not as obvious, there is some evidence of a surface bloom south of Hecla and Black islands as well. The north basin remains comparatively quiet in terms of bloom formation. There appears to be considerable erosion occurring along the north shore and, with the exception of the central basin near Limestone Point and east of Reindeer Island, the rest of the basin appears quite turbid, especially near-shore. (Click on the image to enlarge it.)

Additional images are in the 2012 gallery.

 
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