KRABS: Kelp Rocks Along Beaches

A "kelp rock"

In 2009 I posted about observations of kelp-mediated clast transport (essentially non-buoyant kelps attaching to cobble in the shallow sub-tidal zone, and subsequently being transported apparently due to the increased drag of the kelp) in the Elwha coastal zone. These observations stayed with me as I wrapped up my dissertation and started with Washington Sea Grant. It didn't take long for an opportunity to arise to look further into how important this mechanism of sediment transport really is. With Dan Lieberman at the North Olympic Peninsula Skills Center I developed the KRABS (Kelp Rocks Along BeacheS) project, which was designed to fit in with existing projects that Dan's students' lead that look at marine debris and dead birds on local beaches. The essential idea behind the KRABS project is that students are quantifying the delivery of kelp-attached rocks to beaches on the Elwha delta and Dungeness Spit every month - at this point we have almost two years of data!

Karsten Turrey, a student at the Skills Center who has worked on the project, recently put together an essay titled, "Something Kelpish Going On"...

"Students on the Olympic Peninsula are conducting real-world research at the Elwha River to discover the marine environment, local beaches and themselves. In this blog post I will explain a little about what a kelp rock survey is, why kelp rock surveys are done, and where, when and how the surveys are done.

Some of the crew surveying the beach (from left, Hunter Baker, David Harwell, Karsten Turrey, Dan Lieberman and Conan McCarty).

Kelp is any large, brown, cold-water seaweed, it is not the small green seaweed. It grows in the cold water any where from 2 meters to over 30 meters along the Pacific Coast. A few of the species of kelp common in this area are Alaria marginata “Winged Kelp”, Cymathere triplicata, Nereocystis leutkeana “Bull Kelp” and Pterygophora. The part of the kelp that is attached to the rock is called the “holdfast.” Here is the history of kelp rock surveys on the Olympic Peninsula. The first person to want to do the surveys around here was Ian Miller, the University of Washington, Sea Grant Coastal Hazard Specialist. The first kelp rock survey and protocol on the Peninsula conducted by the North Olympic Natural Resources students was done on the 15th of March, 2011.

A kelp rock survey is where you have a team of people that comb the beach looking for rocks that have kelp attached to them. The group measures the size of the rock, gathers the GPS location, photographs the rock and kelp, determines what type of kelp it is and the condition the kelp is in (old, fresh). Kelp rock surveys are done to see how much of the sediment or rock which has washed up onto the shoreline are from the kelp and if this amount of sediment dragged up has an impact on the shoreline.

Surveys are done monthly on various beaches by Natural Resources students. The surveys are done along beaches. Here on the Olympic Peninsula, my Natural Resources class and I do them along the East Elwha Beach and the West Elwha Beach. Other students of Natural Resources Options Class do the same surveys along the Dungeness Spit in Sequim. There are 4 reaches at each of the Elwha Beaches. There is one reach at the Dungeness Spit. A reach is defined as a length of beach between any two points. For our surveys Ian Miller determined the reaches. We always start with reach 1, but if we finish reach 1, we roll a die and the number it lands on is the next reach we do, if it lands on 1,5 or 6 we roll again. It is important to have materials and procedures ready before starting the kelp rock survey, then we start walking the beach. When we find a kelp rock we put the ruler down to provide scale and take a picture of the rock. After the picture, we measure the rock size on the 3 axes, smallest, intermediate and largest, then we get the GPS location and then identify what type of kelp. We cut the kelp off of the rock so we do not recount it next time we survey.

During my class, October was the time of year we found the most kelp rocks. In one survey my class found over 90 kelp rocks in a small length of shore-line, around 100 yards. I think this is because the fall has stormy weather and rougher currents so it dragged more to shore, or maybe the life cycle of the kelp also has a role to play in it.

It is a very exciting project that I am glad I got to be a part of and I hope that future students can be a part of it as well. Here is a link to the site with all the kelp rock data thank you for reading my blog."

A big piece of kelp with small rocks on it