Alevin escape at Poultney Elementary I was greeted this morning by this e-mail from Keith Harrington of Poultney Elementary School. Subject: Disaster in Poultney Good morning Joe: I came in to a disaster at Poultney Elementary this morning. Our breeder basket had dislodged and was floating upside down in the tank. I don't know what happened other than I was using a new type of basket that uses suction cups to attach to the tank instead of metal hooks. It has been fine, but for some reason the basket broke away from the cups. Everything was fine when I left. We had mesh covering on the filter but checked just to make sure. Nothing was in there but the usual waste. They must have gone straight down into the rocks. I have seen a couple swimming around down there when I stirred things up. Is it possible that they will survive down there and swim up when it is time? Should we attempt to vacuum them out or just leave them alone? As I told the students, we have had several very successful years and have been lucky. Some schools have not been as fortunate. Sometimes things happen. Here's how I responded: You’re probably safer leaving them in the gravel at this point. I think vacuuming them up could be stressful. If, however, they start coming out of the gravel a bit such that you’d be able to net some of them and put them back in the breeder basket, I’d recommend you do that. Your alevin are doing what they would do if they were in the wild. The hardest part of having them out of the basket is that you’ll have a difficulty seeing when some of them die. As a result, their decaying bodies will contribute to ammonia and nitrite problems. (In nature, of course, that problematical water chemistry would just be diluted and flushed away by the flowing stream.) The other problem is that way down on the bottom where they are—20” below the surface of the water where the dry food will float—the fry won’t be as likely to notice food when it is offered to them. In the breeder basket, they’re only about five inches from floating food. You might want to show your students the Brook Trout Life Cycle and/or The Way Of a Trout videos that are on the VTTIC Website. Here's the Brook Trout Life Cycle. It's less than four minutes long. Here's The Way Of a Trout video. It's 30 minutes long but, in my opinion, well worth the time. Both can be found on the Other Trout Videos page of the VTTIC Web site. Deformities On Monday, two different teachers sent me photos of deformed alevin. Suzanne Alfano, of Maple Street School, sent this e-mail: Hi Joe- I pulled this guy out because I thought he was a goner, and then he started swimming around. Have we seen this before? Alevin with a bent tail? Suzanne I responded by saying that, while I've never seen an alevin exactly like hers, a number of teachers over the years have reported and sent me photos of alevin/fry with bent tails. Then soon after, I heard from Dawn Adams, at Rutland High School, wrote, "Thought you might like to see this." And I thought you might like to see Dawn's e-mail signature: O o Dawn S. Adams O o Rutland High School O ><(((*> Science Department o O ><(((*> Alpine Coach o <*)))>< ><(((*> ><(((*> Clever, huh? So how many other deformed fish are there out there? And, if we distributed roughly 10,000 eggs, what's the percentage of deformities? How does that compare to abnormalities in humans and other species? Salinity (What's in your water?, part 1) I also got an interesting e-mail from Rich Carter, at the Greenwood School, who sent this: Hi Joe, Trout are all doing well so far and hoping that continues! We have recently been investigating the relationship between conductivity and the intensity of road salting within our local watershed. This brought up the question of how much salt may be getting into our school's ground/well water. We tested a number of locations of the school's drinking water (various taps, pre and post water softener, pre and post chlorination, direct from the well pump) and found the numbers coming out of our taps are considerably higher (150 vs 450 µS/cm) than or local streams. We then decided to check our trout tank and discovered the numbers were even higher still (600 µS/cm). Last year we had very low ammonia and nitrite numbers (below 0.5) yet still lost around 70% of the fish. Any chance conductivity is playing an issue in our fish loss? I asked whether the school had a water softener. In a follow-up e-mail, Rich added this: It does have a water softener. I figured that was the culprit, but we sampled before and after the softener (according to out facilities guy) and the numbers were the same- both around 450. Before it hits the softener, it gets chlorinated and pumped to a holding tank. Straight from the well (before chlorine and holding tank) the numbers were around 250. From a little digging, I gather the chlorine can increase conductivity, though we add a conditioner to the water before putting it in the tank. But what causes it to increase from 250 to 450? Hmmm! I also sent Rich's question to some of our more knowledgeable TIC experts. Here's how Robb Cramer replied: 600 is a bit high for a closed system for sure but not that much higher than levels often found in water ways. Not being a trout biologist, I can’t specifically comment if that level would affect young developing brook trout. It is higher, as they noted, then you would normally find in a healthy Vermont trout stream. My Maryland friend Chuck Dinkel came back with this. Several years ago one of my Frederick County schools lost its alevin as well as the fish I replaced them with. The teacher and I had a conversation with the building engineer and we found out a water softener had been installed on the school's water supply. The engineer was able to provide us with water pre-softener and the next load of fish did great. I am attaching an article with information I researched during that time. ... I'm also a firm believer in well water. (The article Chuck sent us in short and interesting. It forces you to think about the unintended consequences of modern conveniences we take for granted, e.g., in some situations, water softener use can be like dumping a 40# bag of salt into your local river!) Fractions, proportions, and salinity One of our correspondents in this chain mentioned that the salinity of the water in Rich's tank might be at least partly due to evaporation. How does that work? To keep things simple, let's assume (1) that Rich's measure of "conductivity" can be used as a proxy for salinity, (2) that he starts out with 50 gallons of water in his tank, (3) that every month 50% of the water evaporates and is replaced. and that (4) the salinity of the Greenwood School's tap water is 200. So:
Get the idea? Evaporation can almost continuously raise the salinity. You can use this exercise to help students practice fractions and proportions. Winter road treatments I write this after two consecutive "snow days," when a large portion of Vermont's schools were closed. And over those two days, what was happening out on our roads? The state, town, and city trucks were plowing, yes. But they were also sanding and salting. Rich Carter's interest in/concern about salinity led me to look up the State of Vermont's snow and ice control plan. You can click the link to read it for yourself, but it describes sodium chloride as the "primary snow and ice control material" and adds that "unless combined with other chemicals, sodium chloride is only effective down to approximately 15 degrees F." One of the other materials used is brine. The plan says, "Salt brine is road salt dissolved in water." It mentions that brine can be combined with deicing liquids, which typically include a "corrosion inhibitor." I know that it's become important for people to travel in winter and, if they're going to do that, they need to be safe, but all of this sounds a bit mysterious to me. The question for me--and perhaps for Rich and his students, is: Where does all that salt, brine, deicing liquids, and corrosion inhibitors end up going? Some of your students might want to investigate a question like that.
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Joe Mark is Lead Facilitator of Vermont's Trout in the Classroom program.In June 2012, I retired after 40 years in higher education, having spent the last 32 years of my career as dean at Castleton. One of the first things I volunteered to do in retirement was to work with a parent-friend to help the Dorset School, where his kids and my Vermont grandkids attend, start a TIC program. Gradually that commitment grew into my current role, which is both demanding and highly rewarding. Archives
December 2019
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