Mystery solved: Kelp off Elwha River mouth a rare spring variety found in late summer
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Steve Rubin, a fishery biologist for the U.S. Geological Survey, prepares to place a layer of cheesecloth over a kelp sample from the Elwha River mouth area of the Strait of Juan de Fuca at the Feiro Marine Life Center in Port Angeles last week. The kelp turned out to be a variety normally found in spring near the ocean entrance to the Strait. -- Photo by Keith Thorpe/Peninsula Daily News

By Arwyn Rice
Peninsula Daily News

PORT ANGELES — A mystery kelp found during a survey of Clallam County offshore sea life has been positively identified as a regionally native but rare growth known as Laminaria ephemera.

“Mystery solved,” said Steve Rubin, a fisheries biologist for the U.S. Geological Survey.

The kelp, collected by a team of scientists studying the ecology of the floor of the Strait of Juan de Fuca off the mouth of the now-free flowing Elwha River, was initially thought to be one of two species — L. ephemera or L. yezoensis — neither of which had been recorded at the site before.

After examination under a microscope by Tom Mumford, a retired state Department of Natural Resources kelp specialist in Olympia, it was determined that the kelp was the ephemera variety.

The relatively small, short-lived spring kelp is native to the Strait of Juan de Fuca, but had been known only to grow at Neah Bay, Port Renfrew across the Strait from Neah Bay and in a few areas inside Puget Sound, according to Journal of the California Native Plant Society.

There is a chance L. ephemera is new to the area, with spores carried on the currents from Neah Bay or Vancouver Island into a changed and newly welcoming habitat for the species, he said.

However, Rubin said he thinks the rare kelp always might have grown in Freshwater Bay, into which the Elwha River empties, but was hidden by spring runoff and a lack of previous research.

It is possible the rare kelp normally has a very early spring growth cycle and is gone by the survey's first July visits, Rubin said.

The kelp beds near the Elwha mouth had not been studied before 2008, he said, and there is no spring survey, so there is little known about the area.

Large amounts of sediment has been released during the removal of the Elwha and Glines Canyon dams that begun in September 2011 as part of the $325 million Elwha River restoration project.

The mouth of the Elwha River has undergone dramatic changes since then.

Elwha Dam was removed in March 2012, restoring some sediment flow, and the taller Glines Canyon Dam has been lowered, releasing much of the sediment that had been trapped behind the dams.

Much of that sediment already has moved downstream, clouding the water and covering some sea life that had moved to the mouth after fine sediments ceased flowing from the river by dam construction 100 years ago.

The cloudy water, Rubin theorize, could have blocked sunlight and delayed the development of the short-lived seasonal kelp, and when the water cleared during the summer, the spring kelp began its cycle late.

The multi-agency team has been studying the Elwha offshore sea floor between July and September since 2008 to document the changes in ecology as the river began its free flow.

Rubin said that even in the early July surveys, the team never found aged, mature examples of L. ephemera that might have remained from a spring growth.

This year, the July survey found little seaweed or kelp to be found of any type.

But in August, a large number of young kelp began emerging from the kelp beds, Rubin said.

He asked the team to collect samples during the September survey, when the team found the L. ephemera growing abundantly.

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Reporter Arwyn Rice can be reached at 360-452-2345, ext. 5070, or at arwyn.rice@peninsuladailynews.com.

Last modified: September 23. 2013 7:11PM
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