Benthic survey

Nov 12, 2013

The Algae “Strike Back”: Post Dam Removal Benthic Surveys at the Elwha River Mouth

Algae, Benthic survey, bull kelp, Elwha River, Elwha River Dam Removal, kelp, Olympic National Park, salmon habitat, Scientific diving, U.S. Geologic Survey, Washington Sea Grant 1 Comment

By Sean Sheldrake, Steve Rubin, and Rob Pedersen

EPA science diver photographs kelp samples on board boat.

EPA diver Rob Pedersen photographs samples.

Some of you may have followed our previous blog posts about EPA’s scientific diving program, including 2011 and 2012 reports from the Elwha River mouth in the Strait of Juan de Fuca.

The field site is downstream from the largest dam removal and restoration project to date, a large scale effort to restore wild salmon habitat and other aspects of the natural ecosystem. (For a great overview of the project, check out the webinar series posted by Olympic National Park.)

In this 2013 installment, we share some interesting findings about our benthic survey on how the dam removal is affecting things at the mouth of the river.

This survey involves counting 72 species of invertebrates and 13 species of algae—all of which are experiencing changes, some dramatic, as a result of the largest dam removal and restoration project to date: an experiment of grand scale for Elwha River mouth seafloor residents! The survey is led by the U.S. Geologic Survey, and the team includes Washington Sea Grant, the Lower Elwha Klallam Tribe, and EPA divers.

Stationary light sensor placed near the Elwha River mouth.

Although divers reported seeing fewer algae, the scientists are still crunching the numbers. Early indications suggest a decrease in algae abundance, including the famed, forest-forming “bull kelp” since the removal of the dam. These changes may be due to decreased light levels, a loss of suitable substrate (a growing surface like a rock of some size, or even as small as gravel), or a combination of the two. The team of divers used light sensors at many stations to help to document whether changes in light penetration were occurring at the dive sites to supplement quantitative data about the changes in the seafloor substrate.

In addition, it seems that tubeworms are on the increase in some areas.

This year, early reports indicate a late growing season for algae, perhaps due to the “silt cloud” hanging over areas near the river mouth. A few surprises may be in the works, too, such as the appearance of the rare kelp species pictured below, a sample the team of scientific divers could not immediately identify underwater—a discovery suggesting that as algae are faced with reduced light levels, a species or two not found during previous surveys might be trying to join the party.

Mystery kelp.

Early suspicions from USGS and other experts narrowed down the mystery alga to either Laminaria ephemera or Laminaria yezoensis, and follow up examination confirmed it to be Laminaria ephemera. The unfolding story was covered in the local Peninsula Daily News.

To answer a few questions you might be wondering about all this:

Why does algae matter?
Answer: Well it’s quite a nursery for young marine life and a grocery store for young and old that live in the sea. It’s not unusual to see gray whales and their young grazing in the ‘kelp forest.’ Changes for shellfish are also of great importance to local fisheries. The river is connected to the ocean in so many ways—and the silt keeps coming!
What other changes are there?
Answer: The ongoing study will show changes for nearly 100 species of algae and invertebrates, in addition to fish, for the largest dam removal effort in North America to date.

For more information on the USGS-led study, see: http://www.usgs.gov/elwha, http://pubs.usgs.gov/sir/2011/5120/seaLife/. For a full set of 2013 photographs, see: Elwha 2013.

Read more about the latest in EPA scientific diving at facebook.com/EPADivers.

About the Authors: Sean Sheldrake is part of the Seattle EPA Dive unit and is also a project manager working on the Portland Harbor cleanup in Oregon. Sean Sheldrake serves on the EPA diving safety board, responsible for setting EPA diving policy requirements, where Rob Pedersen has served for many years. In addition, they both work to share contaminated water diving expertise with first responders and others. Steve Rubin is an aquatic biologist specializing in algal species with the USGS and a lead scientist on the survey.

Editor's Note: The opinions expressed herein are those of the author alone. EPA does not verify the accuracy or science of the contents of the blog, nor does EPA endorse the opinions or positions expressed. You may share this post. However, please do not change the title or the content. If you do make changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is www.epa.gov. Some links on this page may redirect users from the EPA website to a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.

Aug 30, 2013

Closing Thoughts, Reflecting on the Trip

Around the Water Cooler, Benthic survey, chequamegon bay, Ecosystem Research, Great Lakes, grts, lake explorer, lake superior, ponar sample, research vessel, Safe and Sustainable Water 1 Comment

By Julie Barker

The author enjoys a tow during the trip.

Our Chequamegon Bay research cruise wrapped up Tuesday, one day early! Our early return was the result of a lot of hard work and the luck of great weather (except the heat, which we northerners are not accustomed to).

Here are some take-away facts of what we accomplished in 10 days:

14 Benthic sleds (a sampling technique).
274 Ponar grabs, which means…
Research Vessel Lake Explorer II
- If you average three rounds of elutriation (separating the samples, as described in our previous post) per sample (normally our minimum), that’s at least 822 times we stuck our arms in sediments up to our elbows swirling round and round. I must say, my right hand and arm are nicely exfoliated.
- If you average 200 organisms per sample, that means we may have approximately 54,800 organisms to now pick out of woody debris, vegetation, or bits of sediment that didn’t get flushed out in elutriation. Once picked, each organism will be individually examined under a microscope and identified as close to species as possible.
830 person hours of work.
We filled out enough field sheets to fill a one-inch thick binder.
We collected approximately 28 gallons worth of samples (seperated out into varying sizes of sample jars).
Sample bottles

In addition to accomplishing the goals of our study, we also had some fun adventures. Last Friday we came across an unmanned boat while en route to a site. It was evident that the boat got loose from its dock because the bow line had parted. For the safety of others, we towed the boat to the nearest residential dock. I had the pleasure of riding in the boat while we towed it, to keep it from fishtailing. A nice lady answered our knock on her door, and agreed to let us leave the runaway boat at her dock for the coast guard.

All in all it was a productive and fun research cruise. However, the work is just beginning. We now need to process the samples in order to enumerate and identify all organisms.

Thank you for following our blog, we hope you enjoyed reading about our work!

About the Author: Julie Barker is an ORISE fellow with EPA’s Midcontinent Ecology Division, part of the Agency’s Office of Research and Development. She has been participating in coastal field study assessments, and her research includes investigating how wetland-nearshore interactions affect coastal fisheries, and exploring novel ways to detect invasive species.

Aug 22, 2013

Chequamegon Bay – Day 6: Separating Samples

Around the Water Cooler, Benthic survey, chequamegon bay, ecosystem, Ecosystem Research, elutriation, Great Lakes, grts, lake explorer, lake superior, Ponar, ponar sample, research vessel, Safe and Sustainable Water 1 Comment

The Art of “Elutriation”

By Will Bartsch

The Lake Explorer II

The benthic survey is progressing nicely. The Lake Explorer II has already sampled all of the deep spots that it can safely access and was docked yesterday.

The 90-foot vessel can operate safely in water as shallow as five meters. However, much of Chequamegon bay is shallower than that. So, we’ve enlisted other boats to join the effort. The Prairie Sounder, being able to operate in one meter of water, got an early start and has been out taking Ponars (a heavy metal sampling device as described in my first post; see below for more about this) in the shallow, coastal areas of the Bay near Ashland. In anticipation of needing another small vessel that can operate in shallow areas, we towed the Research Vessel Tullibee from Duluth on Monday. The Tullibee is 26 feet long and has a cathedral hull that offers extra stability, and was also taking Ponars.

More About Ponars

Deploying a Ponar.

A Ponar is a metal contraption that is designed to be lowered to the bottom of the lake using an overhead cable and winch. It is lowered in an open position and, because it is so heavy, will sink into soft or sandy sediment. Upon hitting bottom, the locking mechanism releases. This allows the jaws to close and collect a sample when it is retrieved. Because it needs to sink into the sediment to work properly, it is not an effective sampling method for areas with hard or rocky bottoms. Even sporadic gravel can cause problems as it doesn’t allow the jaws of the Ponar to properly shut.

Once the Ponar is out of the water, its contents are emptied into a large bin. The next step is to separate the sample into two parts. The first part is all the benthic organisms. The second part is everything else that we don’t want: mud, clay, rocks, sand, sticks and other large organic detritus.

Elutriating a sample.

This process is called elutriation. To elutriate, we mix the sample with water in a hinged basin that has an outlet connected to a fine mesh net with a bottle at the end. After mixing we pour the top water, along with any benthic creatures that were suspended in the process, into the bottle. This is repeated multiple times until only the things we don’t want remain in the basin. The sample that is captured in the bottle is preserved with ethanol and taken back to the lab.

Next we will investigate sites to deploy the benthic sled. We’ll let you know how it goes.

About the Author: Will Bartsch is an ORISE fellow with EPA’s Midcontinent Ecology Division, part of the Agency’s Office of Research and Development. He primarily analyzes data collected as part of the National Coastal Condition Assessment survey, and works on early detection methods for invasive species in Great Lakes coastal embayments.

Aug 20, 2013

Life Aboard the Lake Explorer II – Day 4

Around the Water Cooler, Benthic survey, chequamegon bay, ecosystem, Ecosystem Research, Great Lakes, grts, lake explorer, lake superior, ponar sample, research vessel, Safe and Sustainable Water 1 Comment

By Julie Barker

Research Vessel Lake Explorer II

Yesterday was the fourth day of our efforts sampling the benthic community of Chequamegon Bay. We all got a break over the weekend, but for the next five days, the Lake Explorer II (LE II) will be home to the nine of us contributing to the sampling effort.

What is life like on board? The LE II has five “staterooms” (bedrooms), four of which sleep two, and one that sleeps three (that’s my room). Each has a bunk bed, a small desk, a sink, and a space to keep your personal items (most rooms have high-school-type lockers). One of my favorite things about the staterooms is that each of the bunk beds has curtains that allow the occupant some privacy while sleeping, reading or just taking a break.

By now you may be wondering about bathrooms on the boat. Referred to as “heads,” there are two, and there are two showers aboard. We also have laundry machines available for longer trips. All of the potable water used on the vessel comes from a large storage tank that is filled before every trip.

The galley is where we eat and socialize.

The primary social area on the vessel is the “galley” (kitchen). There are always yummy snacks there. Often a group of us will spend time there in the evenings playing board games like Scrabble, or watching a movie (although we usually never finish because we are all too tired from the workday to stay up). On a typical research trip we eat all of our meals aboard the LE II because we are out in the middle of Lake Superior or docked/anchored in some remote area. However, since this research trip is based out of Ashland, WI, we have been eating breakfast and lunch aboard the vessel and going out in the evenings to explore the different restaurants in the area.

When you want to get a good vantage of your surroundings from the boat, the best place to go is the bridge (where the captain drives, controls, and monitors the vessel). We do all our sampling and sample processing (which we will describe in an upcoming blog post) off the large back deck of the vessel. Although we are not doing much laboratory work on the LE II for this trip, the vessel does have a large science area. We have been using this space primarily for research planning and organizing the benthic samples we have collected so far.

Back deck where we work.

Overall, life on the boat is comfortable, enjoyable, and a unique experience. Sampling trips such as these have been a great way to get to know my co-workers, and I’m sure we are all creating a lot of good memories.

About the Author: Julie Barker is an ORISE fellow with EPA’s Midcontinent Ecology Division, part of the Agency’s Office of Research and Development. She has been participating in field study assessments of coastal embayments, and her research includes investigating how wetland-nearshore interactions affect coastal fisheries, and exploring if underwater video can be effectively used to detect invasive species.

Aug 15, 2013

Starting from the Bottom: Sampling the Benthic Community of Chequamegon Bay, Lake Superior – Day 1

By Will Bartsch

Today is the beginning of a twelve day effort to thoroughly characterize the benthic community of Lake Superior’s Chequamegon Bay. The benthic zone is the lowest level of a body of water, including sediment at the bottom of a lake or ocean. The invertebrate organisms that live on the bottom of lakes and oceans form an important part of the lake’s food web. Because they all have varying degrees of sensitivity to environmental degradation, the presence or absence of certain species can help us determine the condition of the entire aquatic system.

Research Vessel Lake Explorer II

At 8:00 am this morning, the Research Vessel Lake Explorer II cruised out of the Duluth Superior harbor on its way to the Chequamegon Bay. The Lake Explorer II is a 90′ long EPA vessel that is based in Duluth, MN. It can accommodate up to eleven people. The six crew members and scientists aboard will reach their destination after approximately six hours of cruising.

By the time the Lake Explorer II arrives at the Chequamegon Bay, three other scientists in the 26’ Research Vessel Praire Sounder will have already started collecting Ponar samples of the sediment. A Ponar is a heavy, metal sampling device that is lowered from the boat into the soft sediment below. Its jaws automatically close upon retrieval and a sample is brought to the surface. During this survey we will take close to 300 Ponar samples and an additional dozen benthic sled samples (I’ll tell you more about the sled in a later post; stay tuned).

Locations of the survey’s sampling sites in the Chequamegon Bay.

On this twelve day sampling journey, we will travel all around the Chequamegon Bay to get samples that will give us an accurate characterization of the entire benthic community. To choose these sampling locations – or sample points – we used a method called Generalized Random Tessellation Stratified (GRTS). This method uses a spatially-balanced, random selection technique to ensure good areal coverage of the study location and minimize the chance of bias that can come from oversampling particular habitat types.

Throughout this project, my colleague Julie Barker and I will be chronicling our efforts in the field and writing a blog post every few days. We hope that you enjoy the posts and learn more about the methods used to characterize aquatic environments.

About the Author: Will Bartsch is an ORISE fellow with EPA’s Midcontinent Ecology Division, which is part of the Agency’s Office of Research and Development. He primarily analyzes data collected as part of the National Coastal Condition Assessment survey, and he works on early detection methods for invasive species in Great Lakes coastal embayments.

Sep 12, 2012

What’s changed? Post dam removal benthic surveys start at the mouth of the Elwha River

Benthic survey, Dam removal, Elwha River, Scientific diving 3 Comments

By Sean Sheldrake, Steve Rubin, and Alan Humphrey

Schizobranchia insignis tubeworms, Photo by Sean Sheldrake, USEPA.

In this second part of our story (see our earlier blog post), we return to the Elwha to talk more about the techniques involved with the survey.

This USGS-led survey involves counting over 65 species of invertebrates and 23 species of algae—all of which we had to memorize before the survey began. As if that wasn’t enough homework for the dive crews, you have to “sneak” up on your critters to actually count them!

Species like Mya truncata clams can “see” you coming and will retract if they can feel the pressure wave of the diver approaching. Likewise, tubeworms are also underwater detectives with their own early warning sensors for approaching divers. Once Schizobranchia insignis or Eudistylia polymorpha tubeworms retract they look remarkably similar!

In buddy teams, divers go down and count algae (kelp, for example) on one side of the transect, and invertebrates (such as clams) on the other. Our divers must adjust for this “shy” behavior when they reach the bottom and “change things up.” Since each diver must count critters and algae on one side of the transect only, the invertebrate scientist tries to count on the downcurrent side of the transect line. After all, the algae-counting scientist has the benefit of their “prey” not running away from them!

EPA diver Scott Grossman conducts a uniform point count along a straight line "transect" placed on the ocean floor. Photo by Alan Humphrey, USEPA.

In addition to counting all the species within one meter of the transect tape for 30 meters for algae and invertebrates respectively, a separate survey is done called a “uniform point count.” Every ½ meter, the diver puts their finger down along the transect tape and counts only what is beneath it. (Even if the most amazing anemone is an inch away, it doesn’t count!) Statistically, the point count and overall tally of species will give a representative assessment of life in the ocean ecosystem near the Elwha River mouth.

Early survey results included a decrease in algae abundance compared to levels seen before the start of dam removal. The decrease may have been due to light deprivation rather than loss of suitable substrate as there was little obvious accumulation of sand or mud on the seafloor. The divers deployed light sensors at many stations to help to document what sort of change in light penetration was occurring at each site. In addition, it seems that tubeworms are on the increase.

What other changes are there? The study will show the changes for the nearly 100 species of algae and invertebrates, in addition to fish, for the largest dam removal effort in North America to date.

Find out more about the wild survey conditions next week in part three of our story.

For more information on the study, see: http://www.usgs.gov/elwha.

For more information about the EPA dive program, check out their Facebook page at: http://www.facebook.com/EPADivers.

About the authors: Sean Sheldrake is part of the Seattle EPA Dive unit and is also a project manager working on the Portland Harbor cleanup in Oregon. He and Alan Humphrey both serve on the EPA diving safety board, responsible for setting EPA diving policy requirements. In addition, they both work to share contaminated water diving expertise with first responders and others. Steve Rubin is an aquatic biologist specializing in algal species with the USGS and a lead scientist on the survey.