A Bloomin’ Mess
Written by Dr. Klaus L.E. Kaiser and Dr. Paul F. Hamblin
Once again, Laker Erie is on the verge of choking on too much nutrient. In 2011, its western basin had massive blooms of Microcystis and Cladophora sp. algae. It happened before, in the 1960’s, leading to it being declared “dead.” A new paper by AM Michalak and 28 coauthors describes the event in detail; the figure below shows a satellite image of the observed bloom.
Fig. 1. Observed algal blooms, 2011, in western Lake Erie; source: Michalak et al. (2013).
Algae begin to thrive when the concentrations of phosphorous- and nitrogen-type nutrients become overabundant. The algae produce fibers which commonly wash up on the shores. There, the rotting mass produces slimy surfaces and pungent smells. What’s worse though, the stuff not washing up on the shores dies in the water column and sinks to the bottom of the lake. There, its decomposition consumes the water’s oxygen to become uninhabitable by bottom-dwelling organisms which require that oxygen. Furthermore, Microcystis-type algae also produce natural toxins that are highly toxic to a variety of species, man included.
Lake Erie is the fourth largest of the Laurentian Great Lakes (LGLs) with ~26,000 km^2 (~10,000 square miles) of surface area. Lake most other LGLs, it is shared between Canada and the US.
When Lake Erie experienced severe algal blooms several decades, then predominantly of Cladophora sp. ago (in the western basin of Lake Erie, the toxic Microcystis algae were first observed in the mid 1990s), governments on both sides of the border sprang into action. The Great Lakes Water Quality Agreement (GLWQ) of 1972 was based on research findings, much of it undertaken by the then new Canada Centre for Inland Waters in Burlington, Ontario. The GLWQ recognized the need for limitation of excessive nutrient loadings to the lakes in order to prevent such algal blooms. Primarily, the agreement called for the construction of sewage treatment facilities which would remove excessive phosphate loadings from municipal sources.
Lake Erie responded extremely well to the new effluent controls, some people even called it “miraculous.” Within a few years, fishermen’s catches of perch and walleye increased to levels not seen for decades, the shores were no longer covered with smelly decaying algae, and all was fine, again.
Beginning with the early 2000s, blooms of algae, now predominantly of the Microcystis species, started to re-appear in Lake Erie, generally getting more severe over the decade. This trend went into overdrive in 2011.
The Year 2011
The year 2011 saw a severe change in spring time loadings of nutrients to Lake Erie, particularly the western basin. Consequently, the shallow western basin of Lake Erie experienced another dramatic algal bloom of Microcystis. A number of coincidental factors came together, foremost very heavy rainfall in the area in May. Together with winds from the east it promoted algal growth and kept the surface-water-prevalent algae in the western basin.
How that bloomin’ mess looked to a swimmer is shown in Fig. 2.
Fig. 2. Algae experienced by a swimmer.
Undoubtedly, the most important condition was the large nutrient loading from agricultural field runoff. It all combined to produce an algal bloom scenario not experienced before. Fig. 3 shows the total phosphorous (TP; total phosphate) loadings to Lake Erie between 1975 and 2012 (source: R.P. Richards).
Fig. 3. Total spring total phosphorous (TP) loadings (tons/year) to Lake Erie, 1975-2012, source: R.P. Richards.
Unmistakably, Lake Erie has experienced an unusual inflow of phosphate in 2011; we don’t doubt that at all. But there is the question, why, really, was that so? Here, our view differs somewhat from Michalak and coworkers. To understand that, let’s ask the (rhetorical) question: What has changed? Are agricultural fields suddenly so heavily fertilized that the common spring rains result in large algae blooms in Lake Erie? The (partial) answer is found below, in the Need for Yield.
The Need for Yield
The need for yield is nothing new either. However, without the possibility for a substantial increase of the acreage under cultivation, crop yield has become of paramount importance. The recent government mandates of higher minimum (bio)ethanol contents in gasoline are adding emphasis to that need for yield. That requirement creates the (exaggerated) need to grow corn which, in turn, creates a need for maximum agricultural (corn) yield which, in turn, encourages farmers to use every last piece of land to grow corn and often (over)fertilize it in the process to maximize yields.
The truth is that the Environmental Protection Agency’s mandate to convert 40% of the annual corn production to (bio)fuel (i.e., ethanol), is really driving that “Need for Yield” to new extremes. Of course, this mandate is effectively a massive subsidy to farmers that was sold to the public on the basis of energy independence and in some jurisdictions as a means to “save the planet” from “climate warming.” In practice, the opposite is being achieved.
The whole system of (bio)fuel mandates is creating environmental havoc across much of the globe. From palm oil plantations in Asia to corn-for ethanol growing farms in North America, there are many (often hidden) costs to such schemes. The over-fertilization of Lake Erie is just one of them.
What Really is Needed
Michalak and colleagues are putting much emphasis on “meteorological trends consistent with expected future conditions,” i.e. those expected for the future from current climate and precipitation models for the area.
That is where we think differently than the authors of this scientific paper. For example, if you look at the spring TP loadings (Fig. 3), you will note that in the year 2012, it was miniscule relative to 2011. If you add up the loadings for 2011 and 2012, it will be just about the average loading/year for the last few decades. Blaming “climate change” and similar concepts without looking at the actual developments in the field rarely leads to useful insights. After all, climate is defined as a thirty year average of a meteorological variable so one cannot base a climate change on two successive years. Without at least thirty years of data blaming a plankton bloom on climate change is highly speculative.
The algal bloom as described by Michalak and colleagues cannot be properly assessed without looking at the pressing need for maximum corn production, as required under the ethanol mandate. We surmise that changing agricultural practices to increase area and yield have as much or more to do with algal blooms than the climate. Such changes, for example, include changes in fertilizer application (time of year and application methods), pressing into production marginal and previously unused land, drainage of wet lands via tile beds and related changes.
Governments need to revisit the whole idea of climate-control (“-change”), the corn-for-ethanol and related biofuel mandates and other alternative energy ideas in a rational way, unencumbered by claims from NGOs and political motives. Indeed, as Michalak and colleagues point out a truly scientifically guided management is desirable.
Lake Erie would benefit from that.