{"id":234,"date":"2019-04-28T20:07:48","date_gmt":"2019-04-29T00:07:48","guid":{"rendered":"https:\/\/www2.whoi.edu\/staff\/rgast\/?p=234"},"modified":"2019-06-04T14:47:10","modified_gmt":"2019-06-04T18:47:10","slug":"remixed","status":"publish","type":"post","link":"https:\/\/www2.whoi.edu\/staff\/rgast\/remixed\/","title":{"rendered":"REMIXED"},"content":{"rendered":"

R<\/u><\/strong>esearch E<\/u><\/strong>xamining MIX<\/u><\/strong>otrophic E<\/u><\/strong>cology and D<\/u><\/strong>iversity \u2013 what does that actually mean and why are we interested? \u00a0Traditionally, microbial eukaryotes (algae and protists \u2013 not bacteria) are considered either phototrophic (use sunlight to grow) or heterotrophic (eat prey to grow).\u00a0 Mixotrophy refers to an organism\u2019s ability to utilize a combination of these trophic strategies.\u00a0 We are specifically interested in the micro-algae that are able to eat prey.\u00a0 They are not unique to the Antarctic, but this alternative nutritional strategy may help them survive several months of darkness in the polar winter.\u00a0 There is also growing interest in understanding the role that these organisms play in the transfer of nutrients through the food web.\u00a0 In my post on krill I wrote about algae being the \u201cgrass\u201d of the ocean, but not all algae are equal in terms of their nutritional quality \u2013 kind of like iceberg lettuce versus kale.\u00a0 And just like us, heterotrophs can be picky about what they eat.\u00a0 My grandfather used to say that not even rabbits would eat kale (this was a very long time ago, before kale became a \u201csuperfood\u201d).<\/p>\n

BUT, the reason we are studying the mixotrophs in Antarctica is to understand what species are actually using this strategy, how their abundances change in different seasons, what conditions stimulate their grazing activity, and how much they contribute to photosynthesis versus how much they eat.\u00a0 Different mixotrophs are triggered to graze by different environmental conditions, and they will eat different amounts.\u00a0 They will also differ in the amount that they rely on photosynthesis versus grazing.\u00a0 Ultimately this means that their nutritional quality is likely different from \u201cregular\u201d algae, and perhaps better (or worse) for organisms higher in the food web.<\/p>\n

So, how do<\/em> we do this?\u00a0 We are running several different experiments here, but I\u2019m only going to tell you about how we determine the abundance of active mixotrophs in this post.<\/p>\n

First, we collect water \u2013 remember the CTD?\u00a0 Well, it\u2019s still not working, so we\u2019re using those backup buckets (we named them \u201cBob\u201d – see picture below).<\/p>\n

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The water is then placed into clear plastic bags, and fluorescent plastic microspheres (ok, beads) are added.\u00a0 These are about the size of bacteria (0.5 micrometers in diameter), and yes, many of the \u201cgrazers\u201d are stupid enough to eat them.\u00a0 At least briefly.\u00a0 Once they realize the beads are not food, they spit them out.\u00a0 We allow the cells to eat for only 30-45 minutes, then preserve the sample and collect the cells on filters.\u00a0 Now we head to the microscope where we use fluorescence to examine the sample.\u00a0 Algae contain chlorophyll, and this fluoresces red.\u00a0 The DNA is stained with a chemical that makes it look blue\/white.\u00a0 And the beads, they are bright green.\u00a0 Take a look at the image below and see if you can identify the mixotrophs \u2013 there are at least two.\u00a0 They will have a red chloroplast, a blue nucleus and a small green (or yellow-green) dot.\u00a0 The answer will be in my next post.<\/p>\n

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We do lots of these experiments, with replicates, and we count the number of mixotrophs, as well as the number of phototrophs and heterotrophs to get estimates of how many there are.\u00a0 The experiments go pretty quickly, but we spend A LOT of time at the microscope counting cells.<\/p>\n

For those of you wondering what a lab on a ship looks like, I\u2019ve included pictures of our space.\u00a0 We are in the Hydro Lab, in case you want to go to the Antarctic program site and look up the ship layout.\u00a0 It\u2019s quite spacious, although all 4 of us usually end up over in the far corner at several times during the water processing!<\/p>\n

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Research Examining MIXotrophic Ecology and Diversity \u2013 what does that actually mean and why are we interested? \u00a0Traditionally, microbial eukaryotes (algae and protists \u2013 not bacteria) are considered either phototrophic (use sunlight to grow) or heterotrophic (eat prey to grow).\u00a0 Mixotrophy refers to an organism\u2019s ability to utilize a combination of these trophic strategies.\u00a0 We…<\/p>\n","protected":false},"author":46,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[3],"tags":[],"_links":{"self":[{"href":"https:\/\/www2.whoi.edu\/staff\/rgast\/wp-json\/wp\/v2\/posts\/234"}],"collection":[{"href":"https:\/\/www2.whoi.edu\/staff\/rgast\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www2.whoi.edu\/staff\/rgast\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www2.whoi.edu\/staff\/rgast\/wp-json\/wp\/v2\/users\/46"}],"replies":[{"embeddable":true,"href":"https:\/\/www2.whoi.edu\/staff\/rgast\/wp-json\/wp\/v2\/comments?post=234"}],"version-history":[{"count":3,"href":"https:\/\/www2.whoi.edu\/staff\/rgast\/wp-json\/wp\/v2\/posts\/234\/revisions"}],"predecessor-version":[{"id":243,"href":"https:\/\/www2.whoi.edu\/staff\/rgast\/wp-json\/wp\/v2\/posts\/234\/revisions\/243"}],"wp:attachment":[{"href":"https:\/\/www2.whoi.edu\/staff\/rgast\/wp-json\/wp\/v2\/media?parent=234"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www2.whoi.edu\/staff\/rgast\/wp-json\/wp\/v2\/categories?post=234"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www2.whoi.edu\/staff\/rgast\/wp-json\/wp\/v2\/tags?post=234"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}