Sunday, May 31, 2009

Managing ecosystems is hard!

When I was an undergrad, I kept aquaria for the fish. Now I'm keeping aquaria again, but I'm doing it for the ecosystem. I had a 10 gallon tank left over from a failed effort to develop a multitrophic level system for my students to manage - plus a guppy. The guppy was supposed to be the predator in the system - but alas, it turns out guppies are largely herbivorous, or at least they don't like to eat Daphnia. (Fish purists at this point are aghast that I choose guppies, but I was trying to come up with a LOW COST educational exercise.) I also failed miserably to grow free floating algae, and hence all my Daphnia died. But the guppy lived. Thus, my first effort at an engineered ecosystem ended with a tank full of hard, alkaline water, a coat of green slime, and a guppy. That's when I started thinking - ecosystem management isn't easy, is it?

I messed around with adding a few plants to compete with the algae for nutrients, snails and shrimp to eat the algae, but it was a lost cause. Nothing I did put a dent in the algae - although I was still trying "ecosystem management" - no chemical herbicides. Eventually I allowed myself to try physical removal, but even that was only ever a temporary fix. The algae always grew back. I did discover quite a diverse microfauna of flatworms, Hydra (these I had added in culture), and some copepods. No idea where the copepods and flatworms came from.

So - physician, heal thyself! What were my objectives? I decided that I wanted to create a stable ecosystem with at least two trophic levels and no green slime. Allochonthous productivity (i.e. fish flakes) would be allowed. I started with a completely new substrate, reduced lighting, reverse osmosis filtered water (no phosphorous!), and a larger pool of aquatic plants (primary production). Same snails (Herbivores), shrimps (detritivores) and guppies (ammonia factories? Eye candy?). So far, things are going well. My female guppy has produced lots of baby guppies, water quality is excellent, and the snails keep the glass spotless. The hornwort, duckweed, and Amazon sword plants are doing great, the other plants are clinging to life or have succumbed to ... probably snail consumption. I provide a trace element fertilizer and feed the guppies once a day with a variety of dried foods or crushed peas. The snails get a piece of lettuce to chew on once a week.

So - what have I learned about ecosystem management?
  1. The abiotic environment matters duh, that should have been a no brainer - after all the definition of an ecosystem is a community of species plus the abiotic environment. But I think terrestrial ecology doesn't give one the appreciation of power of the abiotic environment that an aquatic environment does.
  2. Biological control isn't perfect Even though my snails keep the glass and substrate clean, the green slime persists in odd corners, especially up in the fine leaves of the hornwort.
  3. Top down controls need support Although I haven't tried this yet, I think if I were to stop feeding the snails "on the side" they would starve to death pretty fast. There is NO algae in the tank. Keeping them fed means that I have more herbivores than the primary production in the tank can support, and thus makes the top down control of algae more effective.
  4. Models are critical especially when your sample size is one. Now, I don't have a simulation model of my aquarium, but I do have a pretty good conceptual model of what's going on in there. My model isn't perfect - for example my understanding of water chemistry is pretty rudimentary. But it provides a framework for thinking about what's going on, and categorizing suprises - like the fact that the water is suddenly all hazy this morning. What's going on there?
So the question remains - how to teach undergrads about ecosystem management? We expect that they will do this as professionals. Is the first time they do it going to be when they're responsible for a National Wildlife Refuge?

And if anyone wants alot of baby guppies ...

Friday, May 15, 2009

A joke of a science

This is a joke that the Possingham lab was (and presumably still is) very fond of - originally appeared in a TREE article written by Katriona Shea and colleagues at an NCEAS working group.

There were four population ecologists shivering and starving, trapped in the boreal winter – a conservation biologist, a fisheries scientist, a theoretical ecologist and a pest manager. A moose appeared on the horizon and came thundering towards them – 1000 kg of warm edible flesh. Each scientist drew on his or her expertise and dealt with the moose using all their respective discipline’s wisdom:
  • The conservation biologist couldn’t decide on an objective. He died wondering whether the moose’s existence was more important than his own.
  • The fisheries scientist used the wrong model. Based on her prior knowledge of elk, she predicted that more moose would be coming, so she starved in anticipation of a herd that never appeared.
  • The theoretical ecologist drew out his laptop and quickly wrote a program to calculate the optimal distance at which to shoot the moose. His calculations proved that the optimal distance was an imaginary number, and he would have been successful had the moose entered imaginary space.
  • The pest manager knew immediately that the moose had to be killed – the only question was with what – pesticide or natural biological control? She opted for the environmentally friendly biological control and released a wolf, which turned around and ate her.
The article is pretty short, and a pithy description of how the objectives of management are what make different disciplines different - the underlying models of population dynamics are the same. I often feel that this point is misunderstood when population dynamics gets mentioned in a seperate bullet point from habitat management - as if managing habitat has nothing to do with population dynamics.

Shea K. et al (1998) Management of Populations in conservation harvesting and control. Trends in Ecology and Evolution 13: 371-376.

Things not to forget about models

"All models are wrong; some of them are useful." - George Box

Wednesday, May 13, 2009

The nature of interdisciplinary work in Nature

Editorial in this week's Nature commenting on the divide between the sciences and humanities as portrayed by C.P. Snow in his "Two Cultures" lecture had this quote:
...those who bring disciplines together in the pursuit of scientific and technical answers find that the best people to have on board are those with deep specialized knowledge, and that such individuals can usually find a place in well-led collaborations.
This resonates with my own experience - in pursuit of "multidisciplinarity" we cannot forget the value of people with deep knowledge. Martin Kemp, in an essay later in the same issue, put the need this way:
What is needed is an education that inculcates a broad mutual understanding of the nature of the various fields of research, so that we might recognize where there special competence and limitations lie.
Such an education is not the same as having students take introductory courses in all disciplines, which is a common outcome when groups get together to train students across disciplines. I believe that a "broad mutual understanding" can only arise by working together with people from other disciplines on common problems - this needs a different course, one that is distinctly interdisciplinary. We still need people to do multiple things - biologists that take some math, and policy analysts that take some biology, but there are few people able to do math, ecology AND policy science. And yet to solve real world problems in river restoration we need to be able to bring Policy analysis, math, hydrogeology, biogeochemistry, and ecology to bear at a minimum.

Saturday, May 9, 2009

Costs of flood control

Rebecca Wodder, president of American Rivers, wrote an interesting piece in this weeks PrairieFire on the rising costs of flood control, and what some communities are doing about it. I don't know where she got her numbers from, but even after spending $123 billion in inflation adjusted federal tax dollars over the last 50 years, the annual cost of flood damage continues to rise at 2.9% per year. That's a stunning set of numbers. Forget fish habitat! Here are real costs - and we don't know how fast they will continue to rise - or what the precise effects of future climate change will be. Why do people keep building on floodplains!

Unbounded uncertainty. Levees and other engineering structures work as long as the system doesn't exceed expectations - expectations that are based on the "period of record".

Friday, May 8, 2009

Not all ecosystem services are sexy

Carcass removal - 'nuff said:

Prosser, P., C. Nattrass, and C. Prosser. 2008. Rate of removal of bird carcasses in arable farmland by predators and scavengers. Ecotoxicology and Environmental Safety 71:601-608.

roads - the ultimate evil

More evidence that roads are the work of the devil - or whatever source of ultimate evil you ascribe to in your personal belief system (actually that's an interesting thought - what is the source of ultimate evil for a humanist?) - published online today in Animal Conservation. Esteban Suárez and colleagues examined a developing wild meat market in Ecuador. The amount of meat available in the market was significantly predicted by the transportation cost from the source - and that was inversely related to access to roads constructed for oil exploitation. The cost of the meat was also very high relative to domestic meat sources, so its clearly not a "supplemental protein source" but meeting some other kind of cultural need.

Another example of how we can't always predict the indirect effects on ecosystems arising from human activities.

E. Suárez, et al 2009. Oil industry, wild meat trade and roads: indirect effects of oil extraction activities in a protected area in north-eastern Ecuador. Animal Conservation (online).

Wednesday, May 6, 2009

Answering the dinner lady

I've been sitting in on a meeting of the Adaptive Management Working Group of the Platte River Recovery Implementation Program - they are discussing the objectives and design of the "flow piece" - the experiment to test the effects of environmental flows on the Central Platte Ecosystem. I've met with these folks before, and its a vibrant and passionately interested group of folks from many different state and federal agencies. We spent the day debating the nature of the experiment, in particular what the main objective is.

But that's not what I wanted to write about - we also had dinner at a local restaurant (Front Street Steakhouse, Ogallala - they even had a pretty good vegie burger, but get the extra mushrooms and onions) - 20 odd biologists, hydrologists and engineers descended on this fine local establishment for an excellent meal and good conversation. As the last few of us were paying our bills, the woman behind the till, asked us "What are you doing with our River?". I promptly passed the buck to Chad Smith - after all, I'm merely a consultant! Chad gave a pretty good short answer - something about planning for environmental restoration - but that wasn't quite enough for her. She had two things on her mind - getting jobs in Ogallala ("Why aren't you doing it NOW") and getting the river back from the "Hunters from Cabela's" into the hands of the farmers. At the time I wasn't quite sure what to make of that last comment about the hunters, but now I think it was her label for people that want the river to do something other than provide irrigation water.

This is the essential tradeoff - water left to go down the river is water that farmers can't use for irrigation, and hence a reduced economic output for the region. Worse, the environmental restoration will not provide the jobs that the dinner lady wanted. The program has lots of money, but much of it is going to people like me - high priced consultants to help design and monitor the restoration. Much also goes to purchasing land, paying taxes and so forth, but relatively little is going to get directly into the economy of Ogallala. I don't think the full story would make the dinner lady very happy at all.

This idea that water not used is wasted isn't limited to Ogallala. I wasn't able to attend the "Future of water for food" conference held this week in my office building, but one of my colleagues that did quoted a speaker there - "water that reaches the sea is water wasted". That's a pretty radical point of view! But as an ecologist, how do I rebut that view? And, will the dinner lady ever accept my answer?

Monday, May 4, 2009

Detecting Ecological Thresholds

A fundamental problem in forecasting the future of ecological systems is the ominous possibility of non-linear responses to perturbations. Multiple stable states are one possible outcome of such things, but even if that doesn't happen, non-linearity makes a mockery of predictions from our standard theoretical tools.

Even picking up thresholds in data is hard - I've used maximum likelihood estimation of split line models to do this, but you have to decide in advance how many different "thresholds" to put into the models. Derek Sonderegger and colleagues present a different way of identifying thresholds in this weeks Frontier's in Ecology and the Environment - using a method called SiZer that examines changes in the derivatives of smooth curves fit to the data with different bandwidths. This is way cool - makes nice pictures too!

Sonderegger et al. (2009) Using SiZer to detect thresholds in ecological data. 7(4):190-195

Friday, May 1, 2009

Supporting women in AM?

Pascale Lane, a professor and blogger from my very own place, wrote a great letter about advice to her daughter as part of the "Letters to our Daughters" project started by Isis the Scientist. As my own daughter will start middle school soon, this letter seems like good advice!

I've often wondered whether I do enough to encourage women in my profession - as a male in a department DOMINATED by males I perhaps should worry about it more. Whenever I've served on search committees I've always gone in with the notion of pushing women candidates as hard as possible - but this is where my efforts go awry, because there often are no women candidates, or the women that do apply are so far down the list of candidates by any objective measure that its impossible to get them on the short list no matter how one tries to skew the numbers. I mean really really far down. So where are all the women applicants?

I've heard that many capable women scientists bail between grad school and academia, but in our case even that is hard to believe. I worry that our department is stuck in a kind of alternate stable state - qualified women don't apply *because* we are dominated by men. Many departments at UNL have used opportunity hires very successfully to dig themselves out of this state, but we're not so good at that - at least not since I've been here. The only tactic I've been able to think of is to actively seek out women that might be interested in a position and ask them to apply - but that kind of cold call requires a certain chutzpah that is in short supply for me. Any other ideas welcome.

Something to think about as I go about training students to become leaders in AM.