We ran the experiment for 17 months and took time point buoyant weight measurements at 0, 3, 9, and 17 months.
We found that corals moved nearshore grew faster in the nearshore than in their home environment and that corals moved offshore struggled to grow much at all!
In fact, nearshore corals grew faster than offshore corals regardless of where they came from.
Which left us wondering WHY???
For context, here is some in-situ temp data and light intensity data. Blue = offshore, red = nearshore site.
We can see that temps overall aren't that different BUT that the extremes (highs and lows) are more extreme (for temp) in the nearshore. Light is also lower nearshore
So, is there a slight metabolic effect (from barely warmer average temps) nearshore? Is light stress an issue? What about nutrient availability and heterotrophy? Or the symbiont community?
If you are interested in the microbiome or algal endosymbiont response I still have samples that I'd love to see analyzed (I currently don't have the equip, expertise, or $ to do this myself). But I can talk about some nutrients and heterotrophy!
We utilized C and N stable isotopes to assess if we could see a signal of land or mangrove derived nutrients in nearshore coral diets. We were also curious about trophic position.
13C on the X, 15N on the Y.
A gross oversimplification is that top left is more heterotrophic and bottom right is more autotrophic.
In general, we would consider more enriched in 15N = more heterotrophic.
We see that nearshore corals are likely to be more heterotrophic. OR...
at least the pool of nutrients between the two reefs appears different. This isotope project was an undergraduate summer project that Isabel G did during her @IDEAGeoscience summer at UNC :)
PS: isotope data are for coral tissue only. Algal endosymb tissue was sadly contaminated w/ carbonate skeleton fragments (isonerds might recognize that this is bad...-- We learned a lesson here).
Plenty more data and figs including physiology (protein, lipid, carbs) using the new methods that @DrSeaBove put together (see previous tweets) are in the paper!
Takeaways: over the short term (17 months) and in the absence of bleaching events, these two species grew faster nearshore than they did offshore. We suspect some degree of heterotrophy or nutrient utilization by corals from/moved nearshore may be the driver there.
In terms of acclimatization, it seems the populations from nearshore struggle to acclimatize to offshore but it is possible that corals moved from offshore to nearshore may have the capacity to acclimatize to the warmer, more variable, and more nutrient rich ecosystems. **...
Of course, take this statement with a grain of salt and recognize the local scale of this experiment and the local scale of variation that exists on these reefs.
More work like this (with more species in more places for longer) is needed to get a good grasp of these dynamics
and the physiology that underlies the responses we and others have seen and will see.
Lastly, I want to circle back and say that this work was not done by me alone. It took a team. A great one! Thanks to @DrSeaBove for being co-PI on this one and our divemaster!
Thanks especially to the many Belizeans that were involved here. We learned so much from ya'll and we are so happy to have a collaboration and friends in Placencia.
Lisa et al at @FOH_Belize were invaluable in all ways and we hope to work together more and that our science is useful/beneficial to you and other folks doing the hard work on the ground every day.
And with that, the last chapter of my phd dissertation is out in the world. As always, you can totally @ me. We can talk about stuff. Methods, trials, tribulations, successes, failures, etc. My "door" is open.
One more thing. IRL friends in the field are so valuable. Thanks to @tacourtne @jp_rippe @DaviesswPhD and more for being sounding boards, idea people, and troubleshooters during all of this.
And thanks to twitter friends like @coraloha who will talk to strangers about isotopes:)
PS: if you are interested in how connected the nearshore and offshore coral pops are in Belize, stay tuned. I heard that @jp_rippe is digging into that :)

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More from @jbaumann3

9 Jun
New pub alert :) #CoralReports
We show that environmental variation and nutrient sources can impact mounding coral growth in Southern Belize. Thread incoming.
DOI: doi.org/10.1007/s00338…
FYI: If anyone wants the pdf please get in touch. You can also check my website for an author proof version :)
This project was a great collaboration between @DrSeaBove @FOH_Belize and I. We were supported by a team of awesome Belizean friends and colleagues without whom we would never have completed the work! Thanks to ya'll who aren't on twitter and those who are (@MoniqueVernonBz )
Read 7 tweets

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