Hello. My name's Linda McNally and I knew through growth and habitat use, juvenile life in lake located in one domain. So my research question was, does die and growth information with trophic levels using stable isotopes of carbon and nitrogen determine if changes and trophic level correspond to changes in growth rates. This isn't grand to the Highland make Association and suburban communities which surround it. To understand the importance of DALYs spawning patterns, and eating habits. And I'll show you some of my methods that I use. So on the left is a marvel tonight, and that is derived from the back of our boat from very slow speeds and for five minutes. And that catches super small fish. And I'll show you later make official like but the middle picture is the fish that we caught from the picture on the right, which is called a purse seine, that and the pursing that has weights on the bottom of it and flow 0s on the top. And we drag it around in a circular formation and its a 100 DeLong. So it's really long and creates a big circle. And that basically captures like a certain sub-sample of the late, how many our swimming in it. And we go at night because the fish dispersing sounds at night and school during the day. So it's easier to get an estimate of how many fish are in the lake if they're just sparks rather than swimming in large groups. So we sampled every two weeks. And the fish usually arrive early May to late May this year. They arrived later in May. I think this is because of temperature and of the lake and how much rain. So the firsts, David, what sampling or night was on July tenth of 2019 and the last day was October 24th, 2019. Because these fish go to the osha and once they are large enough to grow and then they return to the rivers and lakes to spawn. So those are some methods of how I caught fish. Obviously with help I had like two or three years sometimes for people on the boat. So once we got back to the lab on the boat, we had to euthanize the fish with clove oil, which is a humane way to do it. And then we put them over ice and then they put them in the freezer. And when I was ready to dissect them, I had to take him out which location of the lake that we sampled in. We would sample in three sections. So each bag had a letter a, B, or C. And then I had to take out the bag, thaw it out, and get their length and weight of each fish. Assign a personal fish number. Because if I wanted to look into that fish later, use it for what I'm about to tell you, then we would really have to know what Fisher was. And then so it would get its own violence. >> We have to do intensive note-taking to see where that issue went. >> So then I did otoliths dissection, which OLS aren't your bone, and they're located underneath the brain of the fish. Basically there And around hard disks that have circles almost like tree rings, and you can count them and that is how old they are in days. So I had to dissect a bunch of fish, get their otoliths out there, or two per fish? Well, actually there's four, but I had to use two because they're the biggest ones. And then I had to map them in this slide with crystal bonding. I had to wash them and not too hard because they can break. And then I had to look under a microscope and count all the rays. And that was crazy because some other rings are, microscopes are very delicate and the rings are so focused that it really took a lot of power in that microscope to really see down. So they could be off by like one or two days based on fulfilled if the line was for visible. So then another method I did was the stable isotope packing. And another super intensive focused method that I had to take that fish out of the viola, the specific fish number, put it in another vial and then put it in the drying up in a taken out of the drying of in probably like a day or two later, crush it up. >> And then I had to packet entities, tin foil cups, and I'll show you what that looks like, so okay, so the top left is the otolith, and that was a fish caught on June 28th, 2018, is 40 millimeters long. >> And if you count all the little minds, that's how old it would be in days. That's a very clear otolith in the background bonding, that's really cool. And then on the right is the stabilized to packing and use a little spoon almost to put the ground up fish on the, in the tiny tin cut and then put it on the, on the scale and then currently into those tiny little balls in the left. And those were super interesting because they couldn't have any holes actor, you squish them out because you don't want to lose the amount that you weighed on the scale. That's super important to the ratio of how much fish you'd had in there or, and in the isotope reading in general. So and then you would put the tiny little ball in a tray. In that tray would have a number as well, the tracer girls, so that you wouldn't lose the which fish is in wich tray. Cuz that's can get really confusing because they all look the same since they're all tiny little tin foil balls. So here are some of my results. I caught 1285 fish total. I measured in wave them all. So in the top right picture, those are larval airwaves, and those are caught by the larval tone at the one that you dragged behind the boat. You couldn't catch those per se in the purse seine, that because they're too small and they'll slip out of the net. They're super clear and they're hard to see without light. >> So that picture is a pretty good one. >> The largest specially caught was 74 millimeters caught on October 24th. As they grow, they like to go out to see. So I think it was really interesting to see that big of a fish, even though it's not big at all actually. But in general, those pretty big for the fish that I was looking at. The result was that we saw similar patterns in growth as 2018, which was and it's interesting, the bottom left, I mean right picture is Daphnia. That's the zooplankton and a less than ten millimeter fish. And as you can see, the fish would have no way of eating that zooplankton. But as they get older, and they definitely would, and that's what they usually eat. >> And these fish were caught on joint test of 2019. >> So here my stable isotope data, this is for nitrogen. So the more fish eat, the higher nitrogen reading that they will have. So eager they were to increase nitrogen reading that they read. And this was consistent throughout 20182019, which was really cool to see. And then here's my carbon stabilize tube readings. >> Now I'll explain to you what this means. >> So the zooplankton at the bottom, do you see him on the graph there? That's a Daphnia. What they like to eat when they're older. And there's carbon isotope reading is usually negative 33 around there. So the smaller fish like to swim in the pelagic zone. And as you see the 20 millimeters and around there, those Fisher swimming around, negative 29 Carbon. And as you get bigger, like a 40 to 50 millimeters there swimming and like to negative 28 range. And that means that's the littoral zone. And littoral zone as the lock shower. It's where you can a scene of your invader phage. So the smaller fish don't go there because, you know, to get a lot easier. So the small fish like to hang out in the pelagic zone, whereas lot bigger, lot darker, and hard to see where you can't get in. So that's why those fish are swimming where they are. And when they get bigger, they just kind of swim wherever. I think that's what we decided ward like around 60 to 70. They kind of go back to the middle area. So here's my length and weight summary. The red is from 2018 and the blue is the 2019. >> You can see in the weights that day steady line just grew. >> And then in 2019 they had a little wobbly line. I'm not sure why it was different, but it's an interesting time for sure on these fish were caught by person and it was all by the mean Bassos, all the fish calculated that I caught. Here's what I did with the otoliths. So the length of the fish is old compared to what I got is basically the amount of days that they are caught. So or D, So how will they are? So let's look at gray dot from July of 2019 at the bottom, around 18 millimeters long. He's basically a 20 day old fish. >> So the, the date that it was hatched is the same as the length and distance of the length. So pretty interesting. >> And then here are hatched states that I calculated. So they were all caught on same date of July tenth, 2019. And then I have lengths 17-24 3741 millimeter fish. And so as they're older, as you know, their lengths are different. So onto away way, right is the age at capture, which is how many days old I counted them to be. So then I projected their hatch state wishes all in June. And as you remember, I said that the fish arrived late May. It makes sense that they spawn and then created their eggs and hatched all in June, which is really interesting to me. So my conclusions were that the fish group quicker in 20182019, if you remember me showing the weights and how linear it was when it picked up their fish swim in the pelagic zone. Mm, yummy MOOC. The littoral zone. When younger and the earliest touched I got was June sixth of 2019. I probably could've gotten a younger fish. But if I were to measure five millimeter fish or something that tiny, the otoliths small. And I had a hard time getting out of there because it was super hard to get out. So now what I'd like to dissect that small fish, but I'm stands for time sadly, and I want to thank Karen most send for everything that she did for me. I wouldn't have had the bow or anything. I knew nothing about fish really before going into this, and I love fish, but I didn't know anything about, um, so that was awesome. Issues there to guide me through that. Madison, who was she did the 28 teamwork and page Valerie, who is out there all summer with Me, funded by the lake association, and then Sarah Reagan's who also helped with the four steps of the sorting, cuz that was a message to get through, but we did it, so thank you, everyone.