Beaufort Sea, Blog, Boulder Patch, Field Season, Methods, Uncategorized

Algae rocks!

Whither a Boulder Patch without rocks?

The whole reason the Boulder Patch kelp bed exists is because of a large deposit of rocks in Stefansson Sound. These rocks originated in Canada and were dumped by glacial activity in the otherwise silty, muddy Alaskan Beaufort. Over thousands of years, algae and animals began growing on and around these rocks, developing into the diverse ecosystem we see today.

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Sponges, hydroids, and algae taking full advantage of some nice rocks
This field season, we are looking closely at these rocks – collecting them via SCUBA diving, taking them into lab, poking at them – to see how what’s growing on them (aka the epilithic community) changes across the Boulder Patch. Do environmental gradients (e.g. near vs far from river input) and/or the presence of certain key species lead to changes in diversity or algal production? We’re trying to find out. Our results will allow for better predictions of what will happen to Arctic Ocean ecosystems with perturbations such as increased storm frequency, increased river runoff, and decreased sea ice.
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Arley uses Very Scientific Equipment to get encrusting algae off of rocks

 

We see striking differences between rocks from different parts of the Boulder Patch. Observe rock A and rock B:

A. ‘Nearshore’ Rock

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This rock was collected from a shallow, nearshore site

 

B. ‘Offshore’ Rock

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This rock was collected from a deeper, more offshore site

Rock A has relatively high amounts of fluffy red algae. It also has a lot of invertebrates growing on it (can you see the silty barnacles?). Rock B, on the other hand, is mostly covered with beautiful, pink crustose coralline algae (CCA), a red algae that makes a limestone skeleton. in the tropics, CCA is known for ‘gluing’ coral reefs together. In temperate kelp forests, it is resistant to the intense grazing that causes urchin barrens. It is usually a very slow grower compared to other algae.

What is causing these differences? It sure seems to be related to distance from shore… but that is intertwined with other variables such as depth, light, and salinity. With the help of these rocks, we hope to untangle which factors are the most important in determining diversity and productivity across Arctic rocky reefs.

Rock on.

/end rock puns

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