Erin I. Larson
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Colonization Experiment in the Works!

3/14/2016

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​At long last, it’s experiment time! So far, all of my work has been observational, which feels pretty typical for many grad students at the beginning of their dissertations, and I’m excited to be turning the corner into the big kid experimental world, with a pilot run of my experimental design.
 
[For those of you non-scientific method leaning folk, here’s why observations and experiments are such a good pair. First, observations let you establish a pattern – something real that’s happening in the natural world. You may be able to see some correlations with this data, like when X happens, Y also always seems to happen, but you’re not sure if X causes Y, Y causes X, Y causes Z, which causes X, or if X and Y only superficially appear related and actually behave independently. Sometimes fancy statistics help you dig deeper and further and say more about your data and what’s happening in your system, but experiments always remain the gold standard in ecology, since they let you start to unravel these causal pathways, and get at process.
 
So to recap, pattern + process = good science. I’m not knocking natural history, or working with large observational datasets to ask questions over huge spatial gradients that you couldn’t do experimentally, or anything like that, but so much cool science can happen at small spatial scales when you observe something in the natural world, and then poke and prod your system experimentally to see why you saw that pattern. ]
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So excited to start my colonization experiment!
Anyways, colonization experiment! Basically, between my community observations and drift surveys this field season, I’m gathering data to continue to add to the dataset on how communities in Ecuador have changed along a stream stability gradient since our project began sampling them four years ago. I’m also looking at drift propensity differences among macroinvertebrate communities as a possible mechanism for these differences in community stability across sites. Now, at three of these sites, I’m testing how quickly and by whom (meaning macroinvertebrates and algae) cleaned substrate is colonized over time in the stream.
 
This all may sound like glamorous and fancy science, but so far it’s meant collecting and hauling around buckets of rocks from stream banks, scrubbing said rocks to remove any organic matter clinging onto them, baking them in the oven to be extremely sure that they are clean and free of organic material, then drawing on them with paint pens, measuring them and taking pictures from them, and then putting them back in the stream. Because this feels like work that a 5 year old would find fun, I rewarded myself at the end of rock collection day with hot chocolate and animal crackers.
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Ecology fieldwork keeps you young.
 I’ll keep putting 12 rocks out into each stream every two days and then collect them all at once on day 7 to quantify the algal and macroinvertebrates that have colonized each rock. Stay tuned for results!
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One of many rocks ready to be colonized at a high paramo site.
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2016 Ecuador Field Season Update

3/7/2016

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Halfway through my second full field season in Ecuador! The halfway point of a field season always feels like the crux, when goals are starting to be achieved, and yet there's still so much to do. If a PhD is a marathon, then each field season is like another three mile chunk you have to get through on your way to the finish line. 

So far this season, I've been resurveying stream sites that I surveyed last winter for macroinvertebrate communities, basal resources and physical habitat data. In the intervening time between my 2015 and 2016 surveys, huge landslides hit many of our study sites below 3000 meters in the Papallacta drainage here. See the photos below for an extreme example at Guango, one of our most disturbed sites. I'm interested to see how communities have rebounded from this disturbance, and subsequently to understand the mechanisms behind their response. 

To better understand the mechanisms driving community recovery after landslides and floods, I'm doing a drift net study to quantify dispersal across my study streams, using some awesome drift nets that a fellow grad student helped me make. I'm also starting a pilot recolonization experiment in the coming weeks, so fingers crossed that this part of the field marathon goes smoothly.
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Guango in 2015.
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Guango in 2016.
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Drift nets catching unsuspecting bugs in Guango!
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    Above: One of my high páramo study sites in the Río Chalpi drainage near Papallacta, Ecuador.

    Intent

    To bring you into the field with me, to share science that fascinates me, and to ponder the process of doing science. For more frequent updates, follow me on Twitter (@ernlarson)

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