I'm going to try something new - here's a thread of the talk I gave at #WSN2019 with @Matt_Leray. The talk was about the diet of the giant plumose anemone ๐๐ฆ๐ต๐ณ๐ช๐ฅ๐ช๐ถ๐ฎ ๐ง๐ข๐ณ๐ค๐ช๐ฎ๐ฆ๐ฏ and how it compared to the plankton community. Please ask questions!
PC: T. Dwyer.
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PC: T. Dwyer.
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You may be asking: "Why should I care about the diet of anemones?" Well, for one, it's eating some of the things you may like to eat: fishes, clams, and crabs to name a few. They can dominate a system and have been shown to beat out most other things attached to the bottom.
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The bottom of the ocean, especially in the shallows, is dominated by predators consuming the prey floating by (plankton) and can have major impacts on the plankton. Several studies found that this community can completely deplete the nearby floating microalgae.
PC: T. Dwyer
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PC: T. Dwyer
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That's not to say that plankton can't defend themselves. They can be toxic, have standing defenses, or avoid predators. This thread is all about prey selectivity: the consumption of prey in a ratio different from available prey.
PC: P. Bryant - http://nathistoc.bio.uci.edu/crustacea/Larvae/Larva1.htm
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PC: P. Bryant - http://nathistoc.bio.uci.edu/crustacea/Larvae/Larva1.htm
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Why do these types of study matter? They help us understand the effects of predators on their ecosystem, how prey are captured, and how predators partition the available prey. Unfortunately, quantifying the diet of animals that eat plankton is difficult.
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Plankton are frequently microscopic and soft-bodied plankton are digested quicker than hard-bodied ones (think
v
). This makes it difficult to identify plankton beyond the most broad of groups using traditional diet analyses.
PC: B. Vellutini
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PC: B. Vellutini
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For those that aren't aware of how one would traditionally examine gut contents, here's the recipe for working with anemones: Collect an anemone, ice it, cut it in half
, scrape out the contents, rinse with LOTS of alcohol (for the mucus and preservation), ID everything.
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In this dish of gut contents, you can see an amphipod (relative of 
+
) circled. There's a whole lot of anemone tissue also. With new molecular techniques like DNA metabarcoding, we can analyze diets a lot faster, more cheaply, and with less need for taxonomic expertise.
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To metabarcode a sample, all you need to do is collect a community sample, grind it all up, extract the DNA, send that DNA off to a sequencing center, and then match those sequences to previously collected sequences to identify what's in the gut contents.
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We used metabarcoding to compare anemone diets to the available plankton. Plankton was collected with two mesh sizes: 80 um (nearly everything) and 330 um (big things). We wanted to know, ๐๐ต๐ถ๐ฐ๐ต ๐ผ๐ณ ๐๐ต๐ฒ๐๐ฒ ๐๐ฎ๐ ๐บ๐ผ๐ฟ๐ฒ ๐น๐ถ๐ธ๐ฒ ๐๐ต๐ฒ ๐ฎ๐ป๐ฒ๐บ๐ผ๐ป๐ฒ'๐ ๐ฑ๐ถ๐ฒ๐.
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This work was all done at Friday Harbor Labs ( @MarineBiol_FHL ) as part of my PhD work. FHL is located on the San Juan Islands in the Salish Sea in Washington and is a wonderful place to learn about the field of invertebrate zoology, amongst other fields.
PC: J. Mabel
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PC: J. Mabel
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We had two questions for this project: ๐๐ผ๐ฒ๐ ๐๐ต๐ฒ ๐ด๐ถ๐ฎ๐ป๐ ๐ฝ๐น๐๐บ๐ผ๐๐ฒ ๐ฎ๐ป๐ฒ๐บ๐ผ๐ป๐ฒ ๐ต๐ฎ๐๐ฒ ๐ฎ ๐๐ฒ๐น๐ฒ๐ฐ๐๐ถ๐๐ฒ ๐ฑ๐ถ๐ฒ๐ ๐ฎ๐ป๐ฑ ๐ต๐ผ๐ ๐ฑ๐ผ๐ฒ๐ ๐บ๐ฒ๐๐ฎ๐ฏ๐ฎ๐ฟ๐ฐ๐ผ๐ฑ๐ถ๐ป๐ด ๐ฐ๐ผ๐บ๐ฝ๐ฎ๐ฟ๐ฒ ๐๐ผ ๐๐ฟ๐ฎ๐ฑ๐ถ๐๐ถ๐ผ๐ป๐ฎ๐น ๐ด๐๐ ๐ฐ๐ผ๐ป๐๐ฒ๐ป๐ ๐ฎ๐ป๐ฎ๐น๐๐๐ถ๐?
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Now for some results. You can see that there is ๐ฎ ๐๐๐ฟ๐ผ๐ป๐ด ๐๐ถ๐บ๐ถ๐น๐ฎ๐ฟ๐ถ๐๐ ๐ถ๐ป ๐๐ต๐ฒ ๐ฐ๐ผ๐บ๐ฝ๐ผ๐๐ถ๐๐ถ๐ผ๐ป ๐ฏ๐ฒ๐๐๐ฒ๐ฒ๐ป ๐๐ต๐ฒ ๐ฎ๐ป๐ฒ๐บ๐ผ๐ป๐ฒ ๐ด๐๐๐ ๐ฎ๐ป๐ฑ ๐๐ต๐ฒ ๐ด๐ฌ ๐๐บ ๐ณ๐ถ๐น๐๐ฒ๐ฟ๐ฒ๐ฑ ๐ฝ๐น๐ฎ๐ป๐ธ๐๐ผ๐ป and less between the 330 and gut contents.
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If we break up the Arthropoda group and look at subgroups, the differences between the plankton and the anemones becomes more apparent. Blue bars: anemone diets; red bars: plankton. There are some large differences you can see here (including 9% of the diet being insects)!
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The DNA for these insects matches the yellow meadow ant which, at the time of this work, was releasing winged queens and drones, some of which likely ended up in the water. This is an interesting link between the terrestrial and marine environment!
PC: Getty
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PC: Getty
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Here's an nMDS plot. While the nem gut contents (GC) overlap the 80 um plankton samples (indicates similarity), the GC are more dispersed - ๐ป๐ฒ๐บ๐ ๐ฐ๐ฎ๐๐ฐ๐ต ๐ฝ๐ฟ๐ฒ๐ ๐ผ๐๐ฒ๐ฟ ๐ต๐ฟ๐ ๐๐ต๐ถ๐น๐ฒ ๐ฝ๐น๐ฎ๐ป๐ธ๐๐ผ๐ป ๐๐ฎ๐บ๐ฝ๐น๐ฒ๐ ๐ฎ๐ฟ๐ฒ ๐ฎ ๐๐ป๐ฎ๐ฝ๐๐ต๐ผ๐ ๐ถ๐ป ๐๐ถ๐บ๐ฒ.
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When compared to either plankton sampling, there were many species that were significantly less abundant in the gut contents (pref. avoidance or can't be captured), but no significantly more abundant (no. pref. consumption).
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What this means is ๐๐ต๐ฒ๐ฟ๐ฒ ๐ถ๐ ๐ฝ๐ฟ๐ฒ๐ ๐๐ฒ๐น๐ฒ๐ฐ๐๐ถ๐๐ถ๐๐ ๐ถ๐ป ๐๐ต๐ฒ ๐ด๐ถ๐ฎ๐ป๐ ๐ฝ๐น๐๐บ๐ผ๐๐ฒ ๐ฎ๐ป๐ฒ๐บ๐ผ๐ป๐ฒ; they seem to consume all prey that they can capture, missing species that are too small (like rotifers) and good swimmers (like copepods).
PC: Kils
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PC: Kils
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Now let's compare traditional techniques to metabarcoding. Columns are different studies and shaded boxes indicate that that group was present. There's a much higher diversity of groups found using the metabarcoding approach (26 v 7 groups).
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TL;DR:
1. There was prey selectivity
2. Diet was similar to the 80 um plankton samples
3. Surprising amount of terrestrial input (
) in the diet
4. Metabarcoding was an excellent approach for examining the diversity of prey in a plankton predator
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1. There was prey selectivity
2. Diet was similar to the 80 um plankton samples
3. Surprising amount of terrestrial input (

4. Metabarcoding was an excellent approach for examining the diversity of prey in a plankton predator
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This work was done with funding from @AMNH, @UWBiology, and @MarineBiol_FHL. We had lots of lab and field help from @chiton_chitoff, @thefishbotherer, and C. Alexandra.
Thanks to @WSN_Secretariat for the conference and thank you for taking a read!
Thanks to @WSN_Secretariat for the conference and thank you for taking a read!