Catherine Pringle (UGA Aquatic Ecosystem Ecology)


Thank you, Sonia. It’s a pleasure to be
here. I’m really looking forward to highlighting the strength of our aquatic
ecosystem ecology program and the many people who have contributed to that
legacy. We have 11 people on our faculty that are heavy into aquatic, freshwater
ecosystem ecology. So I’ve got to speak fast. I realized if I wrote every word down, I was going to say and did not put any extraneous comments in,
I could finish in eight minutes. But I’ve already taken up a minute
by telling you that. Okay so, I got my dream job at the University of
Georgia’s Odum School, Institute of Ecology back then, 25 years ago. and I was totally thrilled to join the group of aquatic ecologist and others who worked
here. I had been influenced by their work since graduate school. And here are some
of the people that really influenced me. I was thrilled to have close
interactions with these folks when I came here, from Judy Meyer
who’s known for international leadership in stream ecosystem ecology
and her long term stream research at the Coweta LTER site. Bruce Wallace known for his groundbreaking ecosystem level research
on headwater streams. Rebecca Sharitz’s internationally known
wetland ecologist. Gene Helfman, we all know him for his book on fish ecology and Karen Porter and Larry Pomeroy well-known for the microbial loop. You can see there’s a pretty strong female mentorship back then. At a time, in
the early 90s, when that was not always the case in academia. Patty Gowaty and I were hired the same year and we felt like we died and gone to heaven. That was not always the case in other places as I said. As the youngest
faculty member back then, it was like being a kid
in a candy shop and I will be forever grateful to these people for creating
such a nurturing atmosphere of collegiality early in my career. Over the
past two decades the Odum School has developed a strong
focus on tropical freshwater ecosystems and we owe a lot of thanks to these
three gentlemen. Frank Golley’s pioneering research in Puerto Rico, his role in the
development of the Organization for Tropical Studies. Carol Jordan’s
pioneering research in Puerto Rico and All of the work he’s done to contribute
to our understanding of neotropical systems. He’s got multiple books on the subject. And stay tuned he’s
writing another book and that should be out shortly. Ron Carroll’s holistic view of ecosystem ecology and perhaps he’s a little bit
less well known for his pivotal role in the acquisition of eco-lodge San Luis which is a tropical field station in Costa Rica, now under UGA’s umbrella. Research in my lab is
characterized by site-specific, long-term research on tropical, primarily tropical
systems. I only have time to briefly discuss one of these projects in Costa
Rica, which I began when I finished graduate school 30 years ago. I’m one of the oldies in this group tonight– this evening– this afternoon. You can tell I just
got back from Puerto Rico I’m still recovering. Playing bumper cars there’s
no traffic lights because the electricity is out. So, the Costa Rica
project was begun right after I got into grad school and it’s based at the La Selva
Biological Station which is run by the Organization for Tropical Studies. And the project has involved 7 PhD students, 12 master’s students, and 36 undergraduates from the University of Georgia. And this next slide shows all
the PhD alumni of this project. Most of them are now in, all except for one, in faculty positions. Elizabeth Anderson over there… Elizabeth Anderson right
above me here. She’s here with us today. She moderated the special session
yesterday that RBC hosted. She’s a professor at Florida International
University. Okay, so the evolution of this project in Costa Rica: We started out
studying one thing and we never dreamed we would be studying climate change. It’s been consistently funded by a National Science Foundation since 1986, and we
just received our sixth round of funding, which is going to take us to 2022. We have the longest stream chemistry dataset, that we’re aware of published for
South America, the Neotropics. When we began looking at ground water- surface water interactions, we never dreamed we would be looking at climate change, as I
said. But emergent patterns in this long-term stream chemistry dataset led us in
a new direction. We started to see episodic drops in pH. pH would drop to
four and stay that way for four to five months at a time. And these were… We we’re very intrigued by this and we changed our research direction. The maxim ‘be flexible so you don’t get bent out of shape’ applies to this. As I always tell my
students go where the data takes you. So, La Selva when you’re there under the
canopy you forget you’re the base of a dormant volcano. Here, we are at the base
of the volcanic Cordillera. La Selva is at the terminus of two rivers. The
joining of two rivers and the terminus of some old lava flows and there are
these natural inter-basin transfers of volcanic groundwater that’s geothermally
modified because of a hot magma source inside the volcano that run laterally
underground and then emerge at La Selva biological station and some
of the streams at La Selva are affected by this. So as a result we have
two different stream types at La Selva: high-solute
water, which is loaded with phosphorus everybody thought my stream chemistry
was off, when I started this project. Up to 200 micrograms per liter and it’s
also highly buffered with bicarbonate and then these low-solute rivers, the
blue rivers not the red the red is the high solute that are like distilled
water. So, the water runs laterally underground like this from south to
north. And it emerges at this 50 meter
gradient break where the lava flows terminate. So these two different water
types respond differently to climate variation. Ten-year dataset showing the
solute-rich streams in red, solute-poor streams in blue. The high solute streams
have lots of bicarbonate. They’re buffer against pH changes that occurred it was
really dry weather followed by rainfall and the low solute streams are really
vulnerable. The pH you can drop and stay that way for quite a while. So, we define our hypothesized mechanism of this decline in an ‘Ecosystems’ paper. Severe ENSO events result in increased labile carbon in the
soil, lots of litter fall, with the onset of
the wet season you have increased respiration, the water table rises more CO2
gets into the water, it doesn’t invade, you get carbonic acid forming. So the take-home message here is the poorly buffered streams… poorly buffered streams throughout the neotropics poorly buffered streams throughout the
Neotropics are vulnerable to pH declines and most of the streams the tropics are
poorly buffered and since climate model predictions are predicting increased incidents of ENSO-like conditions we have an issue here. The hydrologic conductivity plays a role here though in mitigating effects of
acidity in the case of La Selva because these inter-basin transfers of high
solute water buffer climate-driven acidification in lowland streams. So moving at we have a strong aquatic ecosystem program here; lots of tropical
work. Moving to Puerto Rico. And I’m gonna go really quick now. Our lab has been
involved in long term research at the El Yunque National Forest with the Luquillo LTER project. Alan Covich has been with this project since it’s inception, playing a key role in its long-term success. I don’t have time to tell you
how we were just given this incredible opportunity in the form of tragedy two
back-to-back hurricanes: Irma and Maria have hit the island and now
we’re changing our drought studies to incorporate post-hurricane response. We’re also looking at effects of dams, but I don’t have a chance to talk about
that right now. The amphibian declines project T.A.D.s,
Tropical Amphibian Declines has been a really interesting project lasting for
13 years. Where we’re looking at stream ecosystem response disease driven, Chytrid fungus extirpation of entire assemblages of amphibians. The larval amphibians, the tadpoles when they’re gone the streams turned green, there’s lots of
algae, this is very simplistic but basically there’s no evidence now after
eight years that there’s any functional redundancy in the ecosystem, where other animals are taking over the role of the tadpoles. Scott Connolly and Amanda Rugenski are both on our faculty. They had a lot of … They’re primarily
responsible for this work. They contributed to it when they were
graduate students. We have Jill Anderson with us. She’s got a cross appointment with
genetics. She’s looking at the effects of neotropical
fruit-eating fishes on seed dispersal in wetland plant regeneration. Krista Capps, she’s looking at consumer-driven nutrient cycling a lot of work in the
tropics plus the temperate zone and then In our own backyard, Bud and Mary Freeman have been focusing on aquatic biodiversity. And they have this huge
data collection of long-term work that track dynamics of fish and they’ve laid
a foundation for conservation relevant research on how ecosystems respond to
environmental change. Amy Rosemond’s work on effects of nutrients is well known. Her whole stream experimental approach to examining nutrient effects and detrital
resources Her work’s resulted in numerous key papers only her science paper here is cited And she just got a big new grant with Jonathan Benstead, another alum of UGA, Odum school of ecology, to look at the
effect of stream warming. Finally, the river basin ties us all together, as evidence by yesterday’s very well-attended, I think maybe 1/4 of this
whole room was in this special symposium or workshop designed by the River Basin
Center a freshwater ecosystem ecology reunion if you will and they tie us
together provide infrastructure and so on. So, finally to get back to the man, Gene Odum, himself we have moved forward
beyond describing nature to measuring and understanding her metabolism, we’ve
still got a long ways to go but the Odum school of ecology has provided a
wonderful place to do that. Thank you!

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