Author Archives: Brian Swisher, Animal Caretaker

Why was a famous local Brewmaster talking about zebra mussels?

This article by Brian swisher first appeared in Below the Surface – the blog of the ECHO Lake Center and Aquarium

Are Zebra Mussels Ruining Your Beer

Greg Noonan
photo courtesy of Vermont Pub & Brewery

Are Zebra Mussels Ruining Your Beer

In 2006 Greg Noonan, the late founder of Vermont Pub and Brewery in Burlington wrote this about the water the brewery uses to brew its beers:

[pullquote]“(W)hen we began brewing at Vermont Pub and Brewery 18 years ago, our water was very soft. However, in the intervening time our own “great lake” Champlain has been invaded by zebra mussels. When the little suckers die, their shells disintegrate into calcium carbonate. Our water supply has become much more carbonate, and therefor (sic) more alkaline. As Jim Koch of Sam Adams pointed out to me years ago, alkalinity produces dull-flavored beers.” – from “Brewing Water: Tips from the Pros” in Brew Your Own Magazine, Sept. 2006[/pullquote]

So zebra mussels affect beer brewing?

There is another link between aquatic critters and beer other than isinglass?  As a home brewer and an aquatic ecologist, I was intrigued by this notion.  I had also been putting off any real effort toward understanding water chemistry despite these personal interests.  I decided to investigate this idea that an invasive mussel might affect how beer is made locally and perhaps learn something along the way.

Are Zebra Mussels Ruining Your Beer

Zebra mussels
photo courtesy of Wikimedia commons

First lets clarify what Greg Noonan was saying regarding water softness and alkalinity.  To do this well, we need to understand a bit about the chemistry of water.  Most of us know that water is made up of two hydrogen molecules attached to one oxygen molecule (ie. H two O).  These three molecules arrange themselves in space in a way that more electrons hang out near the oxygen atom, leaving fewer electrons near the two hydrogen atoms.  This means that a molecule of water has a slight negative charge near oxygen and a slight positive charge near the two hydrogens.  This property allows water to react with a wide variety of charged particles (called ions), including other water molecules.  When other substances are added to water, like when water flows through the Basin’s watershed or when a brewer combines malted barley with warm water, reactions between those substances and water will change where electrons spend their time and the numbers of positively and negatively charged ions in the liquid.  Scientists have developed the pH scale to describe the amount of certain positively-charged ions in a liquid.  When there are equal numbers of positively and negatively charged parts of water (like in distilled water) the pH is 7.  When positively charged parts of water out-number the negative the liquid is acidic, pH drops below 7 (with a minimum of 0); when negatively charged parts of water out-number the positive the liquid is alkaline and the pH rises above 7 (with a maximum of 14).  Typically, the pH of Lake Champlain’s water is around 7.8 to 8.

Water hardness is a measure of two particular minerals in water: calcium and magnesium.  Soft water has low concentrations of these minerals and hard water has high concentrations of them.  These minerals typically exist as mineral salts, with positively-charged mineral ions bonded to negatively-charged ions like carbonate and sulfate.  When added to water, these ions separate from one another and react with other charged ions and with the oppositely-charged areas of the water molecules.  In aquatic environments, water can react with rocks like limestone (calcium carbonate) or gypsum (calcium sulfate).  Lake Champlain’s Basin has very little of these minerals in the rocks themselves, but has some calcium carbonate in the form of mussel and snail shells.  When the negatively-charged carbonate ions are in abundance in water, the pH is higher than 7 and is alkaline.

Are Zebra Mussels Ruining Your Beer

A home-brewed German altbier
photo courtesy of B. Swisher

In the statement above, Greg attributed the changes in the water at his brewery to the infestation of zebra mussels, with the death of older zebra mussels adding carbonate and alkalinity to his brewing water. Aha! An ecological hypothesis in disguise!

Did the arrival and subsequent infestation of zebra mussels in Lake Champlain cause a change in levels of carbonate ions?  Although zebra mussels and other freshwater mussels do have shells composed almost entirely of calcium carbonate, the animals themselves grow their own shells by taking in calcium from their aquatic environment and binding it with carbonate.  In fact, the earliest life stages of mussels have no shells at all and swim in the water column.  Current research suggests that in most cases, lakes have to have enough dissolved calcium (8-20 milligrams per Liter) to support an infestation of zebra mussels. Therefore, the overall amount of calcium carbonate in Lake Champlain likely hasn’t changed because zebra mussels have to have the component parts in their environment to create calcium carbonate.  Efforts by the Vermont Department of Environmental Conservation’s Lake Champlain Monitoring team to detect any changes in calcium concentrations caused by zebra mussels confirm this.

However, it is possible that zebra mussels have altered how much calcium carbonate is dissolved in the water (rather than bound up in shells) of Lake Champlain at any given time.  Like most organisms in the lake, they likely grow fastest in the warmer months and cease growing (with older ones dying) in the colder water temperatures of winter.  So it is possible that calcium carbonate levels rise in winter when zebra mussels are no longer taking it up from the water.  Unfortunately the publicly available data (here) collected by the VT DEC is collected only three times each year which makes it unsuitable to answer this question.

Water is the single-most largest ingredient in beer.  

Even before brewers ever understood the complexity of water chemistry in the ways that Mr. Noonan alludes to, the local sources of water shaped the variety of beer styles across the globe.  With the scientific understanding of water and brewing chemistry we now have, anyone can replicate the chemistry of water from well-known brewing centers as Munich, Pilzen, Dublin, London, and Burton-on-Trent.Although Greg Noonan’s hypothesis about why his source water at the Vermont Pub and Brewery changes over time may not be entirely supported by the data, it serves as a shining example of how the ecology of Lake Champlain touches us in unique and perhaps unanticipated ways.

Want to find out more about the flavors and origins of beer? Come join us in sampling the beer styles of Germany at ECHO’s FeBREWary Beer Event on February 14.  More information here.

Lake Trout Moving “Below the Surface” of Lake Champlain

We at ECHO are fortunate to have a wonderful resource in the UVM Rubenstein Ecosystem Science Laboratory housed with us at the Leahy Center for Lake Champlain.  The “Rube” as its called, is the home of some of the most current research on the Lake and its Basin– all done by a dedicated, interested, and sharing group of UVM faculty, students, and staff.  Among them is Dr. Ellen Marsden, who has been studying lake trout in Lake Champlain for a long time.  As you may already know from our video about Champ, Dr. Marsden has a knack for communicating scientific concepts concisely and in an accessible manner.  Sometimes a moving picture can tell us what words cannot.  For instance, she and her graduate student, Bret Ladago, built a underwater Remote Operated Vehicle (ROV) that is capturing remarkable footage of lake trout staging for spawning in shallow reef habitats in Lake Champlain (for the best viewing, maximize the view):

In this one, several lake trout are “shoaling” — staying in one area where they may later spawn.  Several trout in this small group have adult sea lampreyattached to them; some show wounds from previous parasitism by sea lamprey.  To my eyes, the proportion of fish with either sea lamprey attached or wounds is dramatic; yet overall I only can get a really good look at perhaps a dozen individual lake trout.

In this one, a much larger number of fish are moving past the ROV while “schooling.”  Again, there are signs of sea lamprey parasitism on a portion of these fish.  In this case, I can see that there are many more fish in the area and I can examine many more fish for signs of parasitism by sea lamprey than in the previous footage.

This amazing footage provides never-before-seen glimpses into the appearance and behavior of Lake Champlain’s lake trout.  But yet it is important to understand that these are glimpses- just a very small snapshots of the large population of lake trout.  For example, the shoaling video alone could make us believe that despite our efforts to control the numbers of sea lamprey in the Lake, a majority of fish show signs of parasitism.  The second video may lead us to temper that view somewhat.  More footage might reveal other impressions.  How do we know what the true rate of parasitism of lake trout by sea lamprey is?  Are efforts to control sea lamprey changing this over time?

While the video footage is certainly engaging, its not the best tool for estimating rates of sea lamprey parasitism.  For example, because we cannot always see both sides of the trout, we do not know if individual trout may be seen multiple times.  Furthermore, there appears to be behavioral differences between the sets of footage which might indicate that the fish we see may not be average or typical members of the population.

Fisheries science provides the tools we need to answer these questions.  By actually capturing and examining hundreds of large lake trout in a standardized way, the Lake Champlain Fish and Wildlife Management Cooperative has collected data year after year to provide answers.   According to their data (presented here from Lake Champlain Basin Program’s 2012 State of the Lake Report), rates of wounding on both lake trout and atlantic salmon by parasitic sea lamprey have been declining since 2007:

Taken from: http://sol.lcbp.org/biodiversity_impact-sea-lamprey-on-salmon-trout.html

For 2011 around 40% of large lake trout had scars from infestation of sea lamprey.  Ideally, this rate will continue to drop over time and achieve the 25% target rate set by fisheries managers for lake trout.

There are many reasons that we should care about the health of lake trout populations in Lake Champlain.  As large, deep water fish-eating predators, they exist with Atlantic Salmon as one of the top predators in the Lake, playing a role in maintaining the structure of the Lake’s food web.  By virtue of their size and habitat, they are part of the economic draw to the Lake, supporting the business of fishing guides, equipment sales, and fishing license sales.  Some of these dollars get invested back into conservation activities of our state and federal governments.  Additional public dollars support management activities to control the numbers of immature sea lamprey growing up in local streams and rivers and to rear young lake trout for stocking.  Last but not least, as these videos attest, they are graceful, resilient, and beautiful members of our Lake community.

For more information about lake trout in Lake Champlain, check out this story from UVM’s University Communications series, or visit Dr. Marsden’s website.

Shrinking the Phosphorus Cycle: Lake Champlain, Phosphorus, and Time (and Patience)

This interesting article from

Anytime I hear about, read about, overhear, or talk about algae blooms in Lake Champlain an image like this one surfaces in my brain:

Shrinking the Phosphorus Cycle
from: St. Francis University (http://www.stfrancis.edu/content/ns/bromer/ecology/student1/Ecology%20Web%20Page.htm#top)

This graphic representation of the phosphorus cycle, is at the heart of water quality concerns in our Basin and a huge number of basins around the world.  If you follow the arrows which show where the essential nutrient phosphorus flows on the earth to support life as we know it.  Nearly every arrow leads to a living thing, with a few having one step in-between (like the link between the fish and the bacteria and fungi decomposers).  You can follow the arrows of flowing phosphorus for quite a while before reaching a dead end, where phosphorus no longer “feeds” some living things but actually leaves the cycle.  Where does this happen?  At the lake bottom:

Phosphorus only leaves the cycle when either dead organisms get buried in the lake bottom deep enough that decomposers (which actually lie on the lake bottom) do not break them down, or as precipitated phosphorus that settles to the bottom.
Who cares?  Why does this matter?
Getting rid of phosphorus doesn’t happen quickly and because it feeds the growth of organisms that we don’t care for, we struggle about what to do.  In other words, our desire to “clean-up the lake” depends upon changing how much phosphorus flows in the cycle.

I recently attended an informative presentation of the Lake Champlain Basin Program’s State of the Lake and Ecosystem Indicators Report by Bill Howland, the Program Manager for our partner organization.  At the outset, Mr. Howland set the stage for his talk by clarifying that the report is about the status of the lake as shown by the data chosen as indicators since the last report in 2008.  As such, he did not cover what management responses are being implemented in the Basin.  Much of the data he presented centered around phosphorus in the Lake and the Basin’s waters that feed it.  The reports section on phosphorus addresses three questions: How are phosphorous levels in Lake Champlain?  Where does the phosphorus come from?  What is being done to reduce phosphorus concentrations?  Given the media, political, environmental, and regulatory attention that phosphorus gets in our Basin, it makes a lot of sense to pay attention to phosphorus.  Despite the wealth of data about phosphorus entering the lake, its role in producing nuisance algae blooms, and the human desire to reduce the amount of phosphorus in our waterways, I rarely see the questions– “Where does phosphorus go?” and “How long will it take to get there?” — being addressed anywhere.  The answers are important, because without knowing when and how phosphorus may decline in Lake Champlain we cannot know when to see the effects of our collective efforts to “clean up the lake.”

Are there fish in your beer?

As a craft beer lover and avid home brewer I was thrilled when Linda Bowden, ECHO’s Life-Long Learning coordinator, announced that she was planning the beer-themed event called “FeBREWary: The Science of Beer.” As an aquatic biologist, I’m always seeking ways to link our local aquatic fauna to things that people really identify with and care about… like beer!

As it turns out, there is a quite a long history of using fish parts to clarify beer and other fermented beverages. Many fish would sink without some extra buoyancy provided by a structure called an air bladder. An air bladder is essentially a bag made of collagen into which fish can add or remove gas as they move up or down in depth. This allows fish to maintain neutral buoyancy- not sinking or floating, but hovering in one place. As with many anatomical features, air bladders can provide additional functions beyond buoyancy control.

For example, drum use the air bladder to produce and amplify a thumping sound (like a bass drum) during spawning season. Other fish, like long-nose gar and bowfin, can thrive in warmer waters that have low amounts of dissolved oxygen by gulping air and passing oxygen from surface air into their blood stream via their air bladders.

The air bladder is an essential structure for many fish, but it’s the collagen from which it’s made that matters to beer lovers. Consumers of the vast majority of beer styles look for clarity in the glass along with satisfying flavor. Most modern breweries use some form of clarification to achieve the bright clear appearance that consumers expect. Among several options for achieving clarity is isinglass, which is made from- you guessed it- fish air bladders. By extracting and processing fish air bladders, the collagen building blocks are dissolved into an acidic solution to make isinglass. When the isinglass is added to beer, millions of tiny charged collagen particles bind to oppositely charged particles of suspended yeast cells and other dissolved by-products of fermentation (hop oils, protein, etc.) that can make beer cloudy. Once added, the binding action of isinglass forms larger, more dense particles that sink to the bottom of the container and the beer “drops clear.” In as little as two days, a batch of beer will go from hazy (photo on left) to clear (photo on right) and be ready to carbonate and drink.

How the use of fish parts in the brewing process got started is not well known. One of the most likely scenarios that I’ve come across is one in which ancient people used air bladders to carry liquids, including beer. Acidic beverages, like beer and wine, likely dissolved some collagen and created favorable conditions for clarification to occur. Perhaps some ancient ale drinker set down his or her bladder of beer for a day or two, only to discover a clearer drink later on.

Want to find out more about intersection of science and the enjoyment of good beer? Join us at ECHO on the evening of February 9th. Prost!