I recently returned from the 10th Annual International Phycological Congress and Joint Phycological Society of America meeting in Orlando, FL. This was my first international meeting, and while a bit overwhelming in both its breadth AND specificity , it was a great experience. I will digest what I learned and write about what might be of general interest to you all in a later post, but here I’d like to share a few take home messages from my own talk. Starting with my Abstract:
Many field-based studies of macroalgae focus on visible sporophytes, thereby ignoring ecological parameters that may differentially affect the microscopic and difficult to identify early life history stages. This is particularly true for Macrocystis pyrifera, the dominant canopy forming brown alga, which acts as an ecosystem engineer for many kelp forest communities. M. pyrifera follows a biphasic life history typical of other Laminariales. The majority of experimental studies with M. pyrifera involving a field component, are limited to one particular life history stage or otherwise restricted to a short time scale. This study was used to track the survival through adulthood of three different size classes of juvenile M. pyrifera (embryonic sporophytes, 5-10cm, and 1m) when outplanted to the Point Loma kelp forest (San Diego, CA) in three densities. We also compared the survival of these individuals to that of naturally occurring recruits. With this study, we add to the great body of work concerning the natural history of kelp forest ecosystems by experimentally manipulating the root cause of density-dependent mortality among the limiting life history stages of M. pyrifera.
Background info for my talk:
Unfortunately around the end of f June, all of the juvenile macrocystis I collected for outplanting and had been maintaining in the lab came to an untimely end. The exact cause of death is still not clear but I believe a faulty water pump/electrical source, expired nutrient mixture, low water movement, and general stupidity may all be to blame.
Around that time, my undergrad assistant departed to go work on a fishing vessel in Alaska and I panicked for about a week while contemplating running away to southeast Asia to be a divemaster. Then I assembled a dive team of AAUS Scientific diver hopefuls and knocked out in 1 month what had taken me the 3 months prior to plan and assemble. We collected 250 juvenile kelps, braided them into 25cm^2 polypropylene rope mats (5, 15, 30 individuals a piece to represent my 3 density treatments) stored them in the lab until we got a break in the weather. Then in some of the gnarliest wave surge I have had to deal with in the Point Loma Kelp Forest, nailed all 15 mats down over the course of one fairly miserable 3-dive day.
Next we gathered up a bunch of beautiful, ripe sporophylls and got them to release zoospores at three densities in the lab (25/mm^2, 50/mm^2, and 100/mm^2). These little guys settled on 10cm^2 rope mats which were outplanted very carefully by the new hardy scientific divers. They are still microscopic and not very interesting looking, but if you’d like I can post a photo of them later.
Then, with the help of a few grad students who were sick of me begging them for dive help, we collected 70 individuals of roughly 1m in length and nailed them down in three densities:
And then up until 3 days before IPC/PSA dived like crazy trying to find where exactly we placed them during the surge and to measure and count the survivors.
Now, I expected that the low density juvies would do the best. That they would have access to all the light and nutrients they could possibly want with out having to out-compete neighbors that were crowding their space bubble. Oddly enough, juvenile Macrocysits pyrifera may be more complex than I thought. I can only show you super preliminary data, but here is what we have found over just 1 or 2 surveys:
Cool huh? I have that messed up ecological sense that variability, especially when it amounts to results that are wildly different to what you are expecting, is completely awesome. Again THIS IS ALL EXTREMELY PRELIMINARY but I couldn’t help sharing it with you and all the IPC/PSA attendees. Also, even though this deserves more than just a foot note, natural recruitment density and survival is wildly variable too and we are monitoring 30 patches of natural recruits ala Dayton et al. 1984. This is actually the main focus of my study but experimental manipulation is way more fun to do, let alone talk about.
Okay, time to get back in the lab…
P.S. If you are not down on your 90’s RnB and don’t get the reference in my title, check this: http://www.youtube.com/watch?v=uB1D9wWxd2w
And thanks to my undergrad for coming up with such a rad talk title