Monday, November 21, 2011

CERF 2011

Where have I been?  I've been in Daytona Beach Florida, where the 2011 Coastal and Estuarine Research Federation's Biennial conference was held.  
But wait!  What am I doing at a coastal/marine conference?  Excellent question.  I've been working for the last year plus on Great Lakes rivermouth ecosystems, which are the freshwater analogs to estuaries on the coasts.  In fact, they really are estuaries, except for the nit-picky detail of not having salt gradients.  Now, salt gradients in estuaries cause all kinds of interesting density gradients and thus unique water mixing regimes in estuaries.  Those same gradients exist in Great Lakes rivermouths, but they are driven by thermal differences rather than salinity.  Estuaries are also characterized by tidal influences.  Tides are present in Great Lakes rivermouths, but they are very small (on the order of 2-ish cm).  However, Great Lakes are strongly influenced by seiches (wind-driven 'slosh') which are periodic, highly variable and capable of moving large quantities of water and material into rivermouths from the adjacent Great Lake.
See?  Freshwater analogs to estuaries.
Ok, so now that we've established that, let's talk about the CERF conference.  Three things stand out:
  • Estuary researchers don't really pay any attention to any nutrient except nitrogen.  There are a few talks I saw for which this wasn't true, but for the most part nitrogen is the whole focus.  I could go on and on about this, but let's just say I feel this focus on nitrogen alone is probably an oversimplification.
  • Estuary researchers don't really pay much attention to the landscape.  This seems to be changing, but the literature seems to pretty much ignore landscape processes and how they control the delivery of nutrients and water to the estuary.  There were many talks at this conference that also ignored those linkages, but it does seem like there is an increasing focus on how the watershed properties influence the estuarine (and maybe coastal) processes.
  • Estuary researchers don't really seem to apply results from one system to other systems.  This is the one that is hardest for me to get my head around.  So a focus on N might be somewhat justified by bioassays showing N limitation and the lack of N-fixing bloom species in the coastal ecosystems, and treating the watershed as pretty mundane might be ok for systems where oceanic inputs are really high (and far more stable).  But I talked to several researchers at this conference who genuinely believed that their conclusions could not reasonably be applied to other estuaries elsewhere.  This is very much the context dependency discussion we see everywhere in ecology taken to a whole different level.  I'm extraordinarily skeptical that there are not unifying processes that can be identified across the population of estuaries (beyond the salinity/mixing story, which is pretty universally applied).  This is so bad that if you ask someone why they saw a particular result in (for example) the Chesapeake Bay and another researcher saw the opposite result in a Rhode Island Bay, they really can't even begin to explain it.   
Keep in mind these are just my impressions.  Maybe the other thing that stood out is the ignorance so many of these people have of the research that has been done on freshwater ecosystems, and the general disdain they express for that research.  There was a whole session devoted to ecological stoichiometry, and the first 2 talks were combined into 1 so that the topic could be introduced!  Isn't eco-stoich pretty basic to our understanding of how life works at this point?  Am I missing something?  Why was an introduction to the topic at a world-class technical conference necessary?
If I come off as sounding a bit cynical here, it is probably only because I spent a week being looked down on for working in freshwater ecosystems.  The quality of the research I saw at this conference, as a whole, was phenomenal.  I'll try to compile my notes over the next week so that I can highlight the best talks I saw.  I've decided that after a few confrontations for posts I've made in the past about "bad" talks, I'm going to hold off on naming names when I criticize speakers (and just try to be less critical in general). 
However, I have a message for those of you who are accomplished scientists and are going to give a talk at a national conference:

PRACTICE YOUR TALK!!  Trust me, it shows when you don't.

Friday, October 28, 2011

Interesting papers: Wind in Kansas and spider-hopping rivers

  • I wrestle quite often with whether or not to use this blog space to criticize individual papers or presentations.  On the one hand, I feel that scrutiny is a critical part of science, and we should point out all the problems with studies that make them questionable.  On the other hand, actual people are really sensitive to criticism.  I most cases, irrationally sensitive.  I can't count the number of people who got upset about criticisms they received, even when (as far as I can tell) those criticisms were both justified and constructive.  I'm certainly not immune to this myself.  Anyway, thinking about this kind of thing occasionally keeps me from posting.
  • I'm a little too close to this issue, but Kansas Chapter of the Nature Conservancy has published a paper in PLoS ONE mapping out areas where wind development in Kansas will and will not cause environmental problems.  I imagine this paper (and analysis) will become very politicized.
  • River-crossing spiders in Madagascar.  Are they catching bats and birds?  Holy cow.  The paper is actually about the evolution of this ability.
  • Here's a connection I've seen people talk about but never really quantify.  How does the source of carbon to stream biota (allo vs. auto) affect their mercury load?  Since mercury is associated with carbon, you would think the kind of carbon is important.

Tuesday, October 25, 2011

Ecosystem function in a brown world    I highlighted this paper a few days ago as looking interesting, but after reading it, I felt like expanding a bit.  The paper is by Rubbo et al (2011, Aquatic Sciences) and is entitled "Species loss in the brown world:  are heterotrophic systems inherently stable?"
   Before I get into this paper, I think it is probably worthwhile to put this in some sort of perspective.  There are a few fundamental, objective units in biology.  One of these is the cell, one is the individual.  Within a particular ecosystem, in a particular point in time, another might be the species.  Species definitions get confusing when you start thinking about them over evolutionary time-scales or across huge ranges.  In most settings, it is pretty clear that individual cricket frogs form a distinct and unified group when compared to (for instance) Daphnia magna.  In the minds of old-school natural history biologists, and the general public, species are important.  The whole idea of biodiversity is rooted in the idea that more species is somehow better.
   However, when people started thinking about ecosystem functions (nutrient cycles, primary production) and ecosystem services (carbon sequestration, food production, waste disposal), it was trickier than you might imagine to connect biodiversity to these ecosystem processes and products.  Some research suggested it is particular species, rather than diversity that drove ecosystem function.
   The impression I get (although I'm certainly not an expert) is that certain species are thought to be more likely to have big effects on ecosystem processes than others:  Species that dominate overall biomass, top-predators and other 'keystone' species.
   So what did they do in this paper?  Well, essentially they were extending these relationships between ecosystem processes and community composition into very heterotrophic ecosystems:  Forested vernal ponds. These ponds probably don't get a lot of sunlight, so not a lot of primary production.  Instead, most of the system's energy comes from material that falls in from the nearby terrestrial system.
   The authors have done quite a bit of work on these systems.  They decided to see what would happen if they removed the top predators out of these vernal ponds.  So the authors removed all the frogs and salamanders from 12 ponds, and then added them back in to a randomly selected subset of those ponds.
  The really surprising thing is that nothing seemed to happen.  The "ecosystem processes" that they measured (essentially production and respiration) varied a lot, but didn't vary in response to the presence of these frogs and salamanders.  The authors speculated that because this is a heterotrophic system, the base of the food web (being microbial) has such high turnover that changing grazing pressure wasn't able to affect the overall movement of energy up the food web.  Hence the title suggesting the "Brown world" is more resilient.  That sounds good, but doesn't that suggest algae based systems would be very resilient?  Have these kinds of studies been done in streams (which are also heterotrophic)?
   This is a perfect example of a nice study that is simple, easy-to-understand and extremely well-written.  I don't usually think of Aquatic Science as a top-tier journal, but if this is the caliber of paper that is routinely published there, then I feel like I need to change my thinking.

  Michael J. Rubbo, Lisa K. Belden, Sara I. Storrs-Mendez, Jonathan J. Cole, & Joseph M. Kiesecker (2011). Species loss in the brown world: are heterotrophic systems inherently stable? Aquatic Sciences

Wednesday, October 19, 2011

So many interesting papers: Stream fragmentation and the end of NABS.

  • I think I mentioned before, but the North American Benthological Society elected to change its name during the last annual meeting (last Spring).  I don't think changing the name was a horrible idea by any means (the "North American" part is semi-ridiculous and "Benthological" doesn't cover everything the society/journal covers), but it feels really weird to think of NABS as now being SFS (Society of Freshwater Science).  Anyway, this is the last issue of JNABS you will ever see published.  From now on, the journal is Freshwater Science.  Considering there are already journals out there going by the name Freshwater Biology and Freshwater Ecology and Aquatic Sciences and Aquatic Ecology (all of which are comparable or not as good as JNABS), I feel like Freshwater Science now is part of a group as opposed to standing out.  At any rate, I can't imagine this will affect the quality and appeal of the articles published, which is a good thing because....
  • ...JNABS always seems to have articles I'm really interested in.  Just published is a whole special issue on fragmentation in low-order streams (link goes to the intro).  I'm really glad I know longer have to keep a lengthy file on stream obstruction literature just to argue with watershed districts wanting to build dams, but I'm still interested in how connectivity affects ecosystem function.  As far as I know, hardly anyone has looked at that.  Most studies, like these, are focused on simply establishing community composition changes as a result of impoundments.  That's definitely useful, and you can extend that into functional changes in ecosystems, but not directly as far as I know.
  • Burning to prevent tree invasion is pratically gospel in many parts of the central U.S.  I'm not entirely sure why, except that alternative methods of preventing tree invasion seem more difficult and costly (and usually it probably is).  However, this paper in Eco Apps suggests just removing the trees is sometimes sufficient. 
  • Again, the papers I'm mentioning in these bullet-posts look interesting, and I've read the abstracts.  In some cases I've even read the whole paper before posting here.  However, I'm not really evaluating the significance of these papers to the literature or the appropriateness of the methods.  In this case this is particularly true.  This seems really, really cool.  I just don't quite know what it means.
  • Linguistics is pretty cool.  I hardly ever read anything about the topic, but every time I do I find it fascinating.  Like this about word order and the first language of humans.
  • I think my contract (ha!) says I have to point out anything I see that involves spade-foot toads.  In this study, the authors show that the rapidity with which an individual undergoes metamorphosis doesn't really seem to affect the age at which they reach maturity.

Monday, October 17, 2011

Interesting papers: The search for paleo-shoreline caves, burning through carbon reduces N accumulation, and more!

  • I'm not going to lie.  This paper, on how increasing temperature affects nutrient ratios, is in my queue, but I haven't read it yet.  So I shouldn't try to briefly tell you how amazing it looks or that I think it is great...because theoretically it might not be.  But here I am, telling you I think it looks really interesting and I can't wait to read it!
  • I'm fascinated by predator effects that don't involve the predator actually touching or directly interacting with the prey.  I'm particular fascinated by this in stream ecosystems, where I would assume the "smells" of predators would be pretty quickly diluted, but it seems like these effects continue regardless.  At any rate, here's a neat paper on "non-consumptive" effects of predators.  The authors point out, these aren't necessarily non-lethal
  • This article on the search for paleo-nearshore caves in Bermuda is really fascinating.  Kinda amazing how many areas we really still don't know much about. 
  • I've never heard of the term "brown world" used to describe heterotrophic ecosystems before, but I guess it makes sense.  Also very interesting to see that removal of a top predator in this kind of ecosystem apparently doesn't do anything.   
  • Ok.  Really, I haven't read any of these papers in detail yet.  I'm just skimming them and pointing out how interesting they look.  When I read through these, I may include detailed reviews on a few of these.

Caddisflies through time
I recently had a paper from a co-worker (Jason Veldboom) come across my semi-ridiculous RSS feed.  This paper does something a little bit different than any other publication I've seen:  Follow the elemental composition of a population and its (presumably) primary food resource through time.  
The study is straight-forward, in that the authors simply sampled a filter feeding caddisfly larvae and seston through time.  There's interesting stuff all over this paper.  First off, there are 4 streams sampled here, and initially, the caddisflies from those 4 streams have very different nutrient ratios.  As the caddisflies prepare to emerge, however, the nutrient content in all the streams converges.  The paper can't really pinpoint why this is (are all the larvae without this nutrient ratio dying?), a lot of the difference seems to be driven by carbon content (i.e., fat and energy reserves).  
Secondly, the sheer difference in mass among sites is pretty astonishing.  At the beginning of the study, one of the streams has caddisflies that are >3 times bigger than the other streams!  These are streams with virtually identical thermal regimes, in close geographic proximity and we're talking about a single species of caddisfly.  Why would one stream have individuals who start out their life-cycle with such a massive size difference?  This study really can't even address that, but it is definitely interesting.
Third:  A handful of previous studies have sampled particular species in different locations and generally found minimal differences in elemental composition.  This is really the primary form of evidence in favor of a homeostatic model when it comes to elemental composition in invertebrate consumers.  I've never been a fan of these studies being cited as compelling evidence for homeostasis, because although the presumption is that food quality differs among locations, there's no guarantee that's true.  Further, the evidence from experimental manipulations almost always finds biota are more flexible in their elemental composition.  This study actually suggests even finding a lack of variation among sites might be luck all the way around, since only at the very end of their aquatic life-stage (just at pupation) did these caddisflies have similar elemental composition.
Finally, the whole point of the paper is to look at whether growth in these caddisflies is affected by the imbalance between consumer demand and the nutrient composition of the available food resources.  The surrogate for this imbalance is the imbalance between elemental composition of consumer and food (seston), and it does appear to be related to growth rates (at least for P).  However, these relationships are week (R2 ~0.16-0.25).  I imagine this is because this estimate of elemental imbalance is probably only a crude reflection of the imbalance between demand and available nutrient ratios.  
Overall, this paper was excellent.  I'm interested to see other studies on how elemental composition changes though different life-history stages.  I'd be particularly interested to see how tropical and temperate species compare, since energy storage for low-productivity winter months seems likely to strongly affect elemental composition in temperate biota.

Veldboom, J.A., & Haro, R.J. (2011). Stoichiometric relationship between suspension-feeding caddisfly (Trichoptera: Brachycentridae) and seston Hydrobiologia

Thursday, October 13, 2011

Interesting Papers: Trophic levels matter, recharging aquifers, and a special issue on intermittent streams!

  • I saw Mary Power talk last night at UW-La Crosse.  Dr. Power is famous for having demonstrated the effect that trophic cascades can have on aquatic ecosystems.  She did this study where she showed adding fish to a mesocosm can decrease algal production, even though fish preferentially feed on algal grazers.  The reason is that fish aren't very good predators on these algal grazers (they hide effectively), but they are very good predators on invertebrate predators, which are themselves good predators of the algal grazers.  So the fish wipe out the intermediate predators and the grazers go crazy.  And what shows up here in my reader today?  An interesting article about a similar predator-induced cascade in the wolf-coyote-fox chain.  Very interesting. 
  • This paper on fish in a tropical river demonstrates the importance of floodplain nutrients (even when inundated for just a short time) on highly mobile big fish.  I'm not sure why people who build dams don't understand this, but river regulation is just plain bad for most fisheries. 
  • Recharging aquifers using surface water has become a bit of a hot topic.  There are lots of concerns about the quality of the water going back into the rock (does it have contaminants or not?).  I wasn't aware of any real scienctific studies exploring any of these issues, but now I am
  • Oooh look!  Apparently there's a special issue on intermittent streams being published in Aquatic Sciences.  As far as I can tell though, the only thing published so far is the foreword.  Looking forward to the rest of the articles getting out there.