World Environment Day: A Conversation with Aquatic Ecologist Todd Crowl.

Todd Crowl is an aquatic ecologist and the Executive Director of the Institute of Environment at Florida International University, one of the largest institutes associated with environmental research in the country. He is a contributor to our partnership with the Luquillo LTER Schoolyard program in Puerto Rico. The Institute of Environment covers everything from freshwater ecology to marine sciences to terrestrial biodiversity and conservation. In honor of World Environment Day, Cat McGee sat down with Todd to talk about his work and the importance of celebrating this day.

Cat: Can you tell me about the research you conduct?

Todd: I study stream and river systems all over the world. I’ve worked in China, New Zealand, Australia, South America, the Colorado River, and of course I worked with Steven in Puerto Rico on the LTER, looking at the stream communities. I’m interested in water conservation, water policy issues, and now most recently, since I moved to Miami, I’m concentrating more on urban waterways, which is a relatively new thing for me. Miami is one of the densest cities so, if you think about the greater Miami area, it’s 12.5 million people and the Miami River runs right through the center of it. I’ve been thinking a lot about urban development, urban studies, urban rivers and climate change.

Cat: How did you get into this field?

Todd: It’s a story that my father told me when I was a kid. I grew up near Cleveland, Ohio, and when I was about seven or eight years old the Cuyahoga River caught on fire. The river got so polluted that a steamship that was carrying produce set a spark off and the whole river caught on fire.  I was absolutely captivated and fascinated by the fact that humans can pollute a river to the point where it could actually catch on fire. My father said I could just never let that go. The day I went to college I knew I would be studying water systems and rivers and trying to figure out how to minimize human impacts and conserve those kinds of resources.

Cat: Why is World Environment Day and its theme “Ecosystem Restoration” so important to celebrate?

Todd: It’s perfect that that’s the theme this year and that you’re talking to me about it because my group happens to oversee the Everglades restoration program, which is the largest ecosystem restoration program in the world. Our scientists have been working for 30 years helping the Army Corps engineers, all the local resource agencies, EPA, NOAA, NASA, to figure out how to restore the Everglades, which is vitally important to south Florida. One of the points I always try to make is that the Everglades have one of the largest coastal weapons in the world, basically is responsible for our ground water, which is where we get all of our drinking water. We get about 98% of the drinking water for the greater Miami area between the Everglades wetland and the Biscayne aquifer. In the last 50 years we’ve drained the Everglades so that we could have agricultural fields, developments, and we built a road through the Everglades to connect called the Tamiami Trail. Through those activities we’ve shrunk the Everglades to a little less than two-thirds what it used to be. From a pressure problem, the Everglades have gone down by a third. Now with climate change and sea levels rising millimeters a year, the saltwater is pushing against the freshwater and the saltwater is winning. We’re getting saltwater intrusion into the Biscayne aquifer, which is threatening our drinking water. I’m much more worried about losing our fresh water sources than I am about flooding and stuff like that. So, the Everglades restoration is absolutely imperative.

A mangrove branch in the Everglades

Cat: Since you began your career, have you seen more emphasis towards inviting young people to understand the importance of sustainability and respecting the environment, opening the doors to having them see that this is a career opportunity that they can explore for themselves?

Todd: Absolutely. It’s the younger folks that are our only hope. My generation did everything it could to screw up the environment. Now it’s up to the next set of generations to try to fix what we did. I don’t mean that people ever meant to do what they did, that they didn’t care; we just didn’t understand what the long-term ramifications of our activities would be for long-term environmental degradation. So now we spend a lot of our time trying to reach out to kids at early ages, to reach out to teachers, and try to get them to understand the importance in our dependence on the ecosystems that we typically take for granted. We have a plethora of resources and activities for kids to engage in on our institute website. We try to engage students and get them to think about environmental restoration conservation as a career. We have been wildly successful at having undergraduates who go through our CREST Center become research technicians with our grad students and our faculty and completely shift their careers. I have example after example of kids who are now in graduate school instead of medical school. We’re really working hard on the next generation of scientists and environmental managers for them to have a full understanding of how things need to work and then take on the responsibility and spearhead policy changes that will have to incur.

Cat: Can you talk your work with the Luquillo LTER project?

Todd: One of the things we’ve done in Puerto Rico is being able to show that this group of shrimp species that all lived together up in the mountains in these tropical streams are super important for nutrient retention, for processing things like leaf litter, how the food webs function, all the way to providing food to the big fishes that live down on the coastal areas. We’ve been able to show over the last two decades if we remove those shrimp, which is what happens when you build dams on rivers, the shrimp can’t make it up and over the dams and so they disappear because they have to go to the ocean for part of their lifecycle. They live as adults in streams, but the larvae have to go to the salt-water environment in order to complete development, and then they turn around and migrate back up. If you build a dam, they can’t migrate back up and the shrimp disappear, and that impacts the entire ecosystem and could ultimately cause a collapse in the forest. I had the great luck of meeting H.T. Odum before he died when I was a graduate student. He originated the research center down in Luquillo. He asked me what I was doing down there and I said I was sampling the shrimp and looking at how the disturbances like floods and hurricanes impact the shrimp. And he said I got it all backward, I should ask the question, what do the shrimp do for the forest? I just laughed at him and said, what do you mean, what the shrimp do to the forest? How ludicrous is that? In the end, my entire career has been spent showing what the shrimp do for the forest.

Cat: What is your connection to the Luquillo schoolyard program and how might that program inform students’ awareness of the importance of the environment?

Todd: The Luquillo schoolyard program takes our basic data on shrimp population dynamics, on shrimp communities and then the kids play with the different kinds of models that we’ve built. The coqui model is the most famous in terms of the tree frogs. But we have a shrimp model in which you can change the shrimp populations, the densities and that changes different parameters. We have had a whole series of projects now where we are getting school kids all across the island of Puerto Rico to move shrimp above dams to restore the rivers because they can’t get above all the dams. There’s only one really big river left on the whole island of Puerto Rico that’s undammed and that’s the Mameyes River. We got that river designated through legal ways as a wild safe river, so it can never be dammed. Every other major river in Puerto Rico is dammed. If you go above those dams and go to the rivers up there, they are slimy, they’re full of bacteria, they look horrible. They look like copper mines. As soon as you put shrimp back in them, the shrimp clean all that stuff up, they eat the bacteria, they clean off the rocks, and those streams look just as beautiful and clear as the ones in Luquillo. Within just four weeks, you can see a transformation.  And that kind of activity where kids are transplanting the shrimp back above the dams and then we documented the recovery of the streams, you can’t teach that in a classroom. This way you can show whole communities what happens.

Before shrimp are introduced in the river
After shrimp are introduced in the river

Cat: What has been the most surprising discovery you’ve made when it comes to the environment and sustainability in your career as a researcher?

Todd: When I first started doing all these experiments and trying to understand the importance of these shrimp, I was thinking about it more from a biodiversity conservation standpoint. If we kept building dams, we’d lose all these species of shrimp, they go extinct. But when we started doing experiments where we manipulated the shrimp communities and then measured the amount of nitrogen phosphorous and carbon that was leaking out of the forest and through the streams, never did I dream that these little tiny shrimp would be responsible for the retention of thousands of kilograms of nutrients on an annual basis. Tropical forests, in general, are nutrient limited because there’s so much rain, the soils are really poor, they’re mostly clay, everything leaches out, and so every molecule of nitrogen and phosphorous is precious to a tropical rainforest. They’re among the most productive ecosystems in the world. So, how can you have an ecosystem with no nutrients be the most productive thing in the world? It’s because they are so adapted to recycling those nutrients. But never in my life did I dream that we would be able to show that it’s this group of shrimp in the little river systems that basically are in large part responsible for the retention of those really rare nutrients.

Cat: Are there things that people can do in their day-to-day life, that they can think about doing that make a good contribution to the goals set out by World Environment Day?

Todd: All ecosystems are highly connected systems. Things like adding fertilizer to your grass so it’s a little bit greener or spraying pesticides so you don’t have as many mosquitos, in a place like Chicago, all of that stuff runs off during the next rain event and it all gets into the lake. Little things can have a huge impact. So, if you don’t have to fertilize your grass, if it doesn’t have to be one shade greener, don’t do it. If you see plastic bottles and plastic straws in the street, pick them up and throw them away, because eventually that stuff will wash into the lake. And if we’ve learned anything in the past five years that probably should be highlighted is microplastics are going to be one of our biggest issues and it’s going to be virtually impossible to solve it.

Cat:  What characteristics do you identify in young people that make for a good investigator?

Todd: Inquisitiveness. The kids who ask questions, the kids that will not take a simple answer and come back and say what about this or why this? It’s that innate need to ask questions and to understand and to not take a simple answer. Those are the kids that ultimately bloom and turn in to be the best scientists and the most important folks.

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