Water, water everywhere — but it’s all covered in algae. Photo: © John Delmotte
By Patrick Doran, Director of Conservation, The Nature Conservancy in Michigan
I felt many things as the news unfolded of the Toledo water shutdown and Lake Erie algal bloom last month.
Surprise was not one of them.
When I first heard of the water shutdown, my first thoughts went to the old mariner’s rhyme:
Water, water, every where,
Nor any drop to drink.
Nor, I might add, a drop for fishing, or swimming, or waterskiing, or…
Consider this: Almost a half-million people sat on the shores of one of the world’s greatest freshwater resources, and relied upon plastic water bottles carted in from destinations unknown.
Are we suffering the plight of the ancient mariner and his crew?
Recipe for an Algal Bloom
An algal bloom in Lake Erie’s western basin. Photo: © John Delmotte
Lake Erie, in particular the western third of the lake, is the warmest and shallowest of the Great Lakes. This, in turn, makes the lake highly productive – for fish, insects and birds.
Lake Erie is also surrounded by people. It is the most developed and the most utilized Great Lake – over half the registered boats in the Great Lakes region are on Lake Erie. I grew up there, angling for some of those fish and waterskiing on the calm waters.
But the landscape has been highly modified and the lake suffers the impact of many stressors (see Allan et al.), with one of the biggest stressors being the loading of phosphorus into the system from agricultural, industrial, and urban sources.
Add a bunch of nutrients to a shallow, warm body of water and you have a recipe for an algal bloom.
Algal blooms, and the algae that form them, naturally occur in the system. In Lake Erie, a bloom of Microcystis, and the subsequent production of microcystin, a toxin, was the culprit that shut down the Toledo water supply.
Microcystis is the most common cyanobacterium in Lake Erie, basically occurring all across the lake in all seasons of the year, but usually at densities that don’t result in problems for those using the lake for recreation or as a source of drinking water.
But sometimes populations of these organisms take off, causing a Harmful Algal Bloom (HAB).
Many factors contribute to the increased incidence and extent of HABs occurring in Western Lake Erie and other parts of the Great Lakes and almost each of these are a result of our human impacts.
* Invasive zebra and quagga mussels both selectively avoid cyanobacteria, allowing them to survive in the system. They filter the beneficial green algae out of the water but not the blue-green algae (which the cyanobacteria uses as habitat). This leads to a disproportion of blue-green algae which in turn promotes cyanobacteria growth.
* Agricultural practices, mainly the management of phosphorus and soil moisture (through tile drainage) necessary to produce crops that feed the region, have changed in recent decades in a way that has increased the amount of dissolved reactive phosphorus, or DRP, in the system which is a readily available form of this essential nutrient on which cyanobacteria like Microcystis can thrive.
* Climate patterns in the region are changing. Warmer air temperatures lead to warmer water temperatures, again creating better conditions in which to grow cyanobacteria.
* Spring precipitation has increased which, in turn, increases the delivery of phosphorus to the system, just at the time of greatest need for cyanobacteria.
* All these factors, combined with random seasonal events such as changes in wind patterns, create a recipe for HABs.
The Electric Green Algae Test
Photo: © NASA Earth Observatory
But why should we care about HABs? Well, there multiple impacts to both people and nature beyond the well-publicized recent water shutdown.
First, the simple fact is that people do not want to swim or waterski or go boating or fishing when the water is colored electric green.
In the least it is annoying, but there exists the potential for skin irritations, and, if ingested, rarer cases of gastrointestinal problems or, in extreme cases, liver failure.
People can at least avoid the lake; fish cannot. The algal blooms can lead to low oxygen conditions in portions of Lake Erie which causes fill kills and negatively impacts the fisheries. Furthermore, there is evidence that HABs can impact birds as well.
The need to abate the potential of these blooms cannot be overstated.
In 2011, the lake experienced the largest harmful algal bloom on record. It didn’t shut down any water supplies, but did impact the use of the lake and the associated economies A 2013 bloom did shut down water supplies, but “only” to a couple thousand people just to the east of Toledo. These were big local stories but at the time didn’t capture national attention.
The 2014 bloom was predicted to be above average, similar to that of 2013. But the bloom began and the wind and currents blew it right over the Toledo water supply. Shortly thereafter Microcystis became a household name.
The thing is, we know what to do. But I am not sure we know how to do it.
The agricultural industry is part of the solution. A big part. The blooms can be predicted from the amount of water and total phosphorus leaving the Maumee river in the spring of the year. Most of this phosphorus comes from our agricultural lands.
Other sectors of society are part of the solution. We still have phosphorus entering from our municipal water infrastructure, like sewage and wastewater overflow.
In addition, there are other legacy sources of phosphorus – in the banks of the tributaries and in the sediments of the lake.
But rather than pointing fingers at one another to assign blame, we need to raise hands and step up to be part of the solution.
We need to agree upon goals and collaborative strategies for phosphorus reduction that will ensure we develop and effectively use the tools, technologies, practices, and policies that truly address the problem, rather than the symptoms.
Outside our front doors, we can look out upon one of the world’s greatest freshwater resources. And this summer over a half million people could not drink the water.
How will we free ourselves from the curses of these self-imposed burdens? The answers may not be easy but we all have to be part of finding them, unless we want the Rhyme of the Ancient Mariner to become an annual reality.
Opinions expressed on Cool Green Science and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of the Nature Conservancy.