University of Nevada and USGS – Nearshore Pilot Monitoring Project – Periphyton Replication Project – Ward Creek study site

November 1, 2015 martin

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An exciting thing about being involved with Project Baseline: Lake Tahoe is that as time has moved forward from that “stake in the ground” beginning (2011), we have broadened our involvement into some pretty cool aspects of environmental data collection in Tahoe; which has led to some very incredible dives.

The Team formulating a strategy & logistics for our dive.

On Halloween we donned our “SCUBA diving underwater data collector and citizen scientist” costume and headed toward 200 feet. Our dive site was about one-quarter mile south of Sunnyside resort on Tahoe’s west shore. This area is a popular area of study for our hosts, UNR’s College of Science and the Nevada division of the USGS. New Millennium diver Martin M. and GUE’s Project Baseline Director, Todd K. were tasked with establishing a periphyton (algae) study transect from 3 feet out to 200 feet. Supporting us on the surface was past member of New Millennium Dive Expeditions, Byron P. Representing UNR was Dr. Sudeep Chandra and from the USGS was David Smith.

The original plan for these dives was to utilize the New Millennium dive boat but at 5pm on Friday the 30^th, NOAA put out a Lake Wind Advisory – which typically recommends small crafts like ours stay off the lake. So we heeded the advice, left the boat in the garage and explored another plan which would see us working directly off the beach. We thought we had close beach access to the study site – not to be – so we had to again readjust our plan once arriving at the lake. Turns out we needed to move equipment and supplies about 10 minutes down the beach south or about 1250 feet. Hauling our gear fully equipped and in our drysuits would have been incredibly difficult and fraught with the risk of turning an ankle on the lake rock dominated beach so, we decided that we would enter the water at the beach parking and utilize tour Dive Propulsion Vehicles (DPV’S) to transport us and our in water supplies the 1250 feet down the beach while Byron, David and Sudeep would carry other supplies to the study area as they were not diving.

The goals for today were to 1) conduct 2 dives of about 45 minutes per dive total including decompression, 2) establish transects (fixed line) from 3’ to 200’ at the Ward Creek Site and on Stateline Point, 3) place 4 bricks at each sampling depth during ascent 200ft, 135ft, 100ft, 65ft & 33ft, 4) place 4 bricks at the 9ft and 3ft sampling depths but utilizing a hold down system for the bricks due to potential rough water as we head into winter and 5) collect two similar sized rock samples from 33ft and 9ft then place them in separate and marked zip-lock bags. Spoiler Alert!!! We were only able to successfully complete the dive at the Ward Creek study area and 45 minutes underwater turned into 125!

Martin placing the 1m (3ft) stake and Todd organizing line.

Here’s our tale… we parked the vehicles at Sunnyside at approximately 9:30 and assessed the area. First obstacle overcome… distance to the study area …DPV’s. Second order of business was to strategize our underwater objectives. Because we had so many individual underwater tasks, we began with an organizational briefing and evaluation of the objectives on land. What we were basically going to do was to set up algae growth mediums at the various depths. These mediums were bricks. Two bricks would be covered with a wire mesh that let light through, necessary for algae growth, but keeping crayfish out. Crayfish were introduced to Tahoe in 1934… on purpose! They potentially feed upon the algae so the scientists need to account for this potential. The other two bricks would be uncovered. Team project one was to build 7 cages just large enough to contain the two bricks. These turned out to be about 10-12 inches square.

With the on land task of building the mesh cages complete, the next step was to figure out how to properly secure the bricks at the 3 foot and 9 foot stations. This was of concern because in a big winter storm with heavy winds, these depths could receive quite vigorous water movement and we did not want to return in 3 months to find the bricks gone as they are a critical part of this study. Once we discussed several ideas, we decided to let Byron, Dave and Sudeep create these while Martin and Todd were underwater.

Mesh cage – 12in x 8in to keep Crayfish out.

With the sampling station infrastructure designed, we then had to organize everything that was to go underwater into two cashes that would be manageable underwater by two divers. A digression here, we were supposed to have a team of 3 but one of our very loyal and committed divers ran into a huge drysuit problem and simply did not have the equipment to fix his suit in time for the dive. In hindsight, maybe we could have eliminated the photo tasks. Unfortunately this is one of the most important underwater aspects of work like this. A picture is truly worth a 1000 words and even more critical when documenting the underwater world. We would simply have to rise to the challenge; we did and laughed a bunch.

The next addition to our basic objective is that David with the USGS wanted us to place digital temperature sensors with specific markings at specific depths. Not a huge task in and of itself but the importance of placing the correctly marked sensor at the proper depth meant that we had to do some organization underwater. We felt that one more task while there was worth the data it would provide. So added to the task and equipment list, we continued.

Here was the inventory that we had to transport from the surface to depth: 20 bricks – 5 wire mesh boxes – 5 stakes to hold down the mesh boxes – a 5lb hammer to drive those stakes in – an auger to hold the end of the transect line ending at 200 feet – a spool of line with 1500’ of 1/8” line – 5 digital temperature monitors – 20, 9 inch plastic zip ties – 4 zip-lock bags – all our normal gear and the camera system (a 200’ rated camera that at 200’…did not work but thankfully worked shallower).

3m (9ft) station.

2 bricks uncovered, 2 covered & Temp Sensor (up rt cnr)

Todd, who had the most experience placing line due to his cave diving experience over the past 25 years, would run the line on the spool, carry the auger, hammer and 8 bricks (4 for the 200 foot station and 4 for the 135 foot station); his bricks would be in two separate bags. The rest, Martin would carry with the bulk of it, 12 bricks, 3 mesh boxes and 3 stakes being dropped off at 100 feet on the way down for deployment on the way up at 100ft, 65ft and 33ft depths.

With all supplies and a solid mission plan in place, the dive began about 1pm; the 3’ starting point is at the coordinates, 39.135724°, -120.151568°.

You are probably beginning to understand now why what was originally planned to be a 45 minute dive, turned out to be 125 – we just had a lot of supplies and coordination to deal with; doing these types of dives has no “instruction manual”. You simply have to formulate a plan and execute then assess for improvement.

The time factor though was effected by another issue. Typically this side of the lake is quite steep and depth increases very rapidly but, yes, you guessed it, that was not to be for us. The underwater slope here was much more gradual and we estimate that we laid down approximately 1000-1200 feet of line as it took us almost 25 minutes to reach 200 feet; our original plan was for about 10-15 minutes with a distance planned of about 750 feet per the chart based upon the coordinates we were originally provided. Unfortunately the chart was not as accurate as you would expect; we called this the Ward Creek study area but in fact we were about one-half a mile north of the Ward Creek outflow.

The only image from 200ft

Upon reaching 200’ we found a discarded steel I-Beam (typically used in dock construction and as we have seen, many construction companies simply discard their waste underwater – who is going to know! – this really pisses me off!). We tied off our 200’ end of the transect line too this I-Beam (re-purposing) and brought the auger back to use another day. After organizing all the supplies and locating the proper temperature sensor for this depth, the bricks were placed, the mesh box was placed over the two appropriately marked bricks, the temperature sensor was placed and then out came the camera. Unfortunately the camera, only rated for 200 feet, took one shot as the water pressure would not let the shutter button return to its live position. We only captured one image at the 200 foot station. We then moved up to the next depth, 135’ and repeated the station set-up steps and then moved up again over the next 30 minutes setting up all the appropriate stations at each of the selected depths.

One of the 7 Periphyton (Algae) growth stations – 100ft.

2 bricks uncovered, 2 covered, Temp sensor #5

As in any dive mission of an inaugural nature, the unknowns are many. Upon completion of this dive we could really see the shortcomings and began a much better mission plan for the establishment of the second transect to be placed at Stateline Point. The most notable realization is that this dive requires two teams of divers. One to handle the establishment of the transect line and the 200 foot and 135 foot stations and that same team moving up and completing decompression while establishing the 9 foot and 3 foot stations. The second team would drop to 100 feet and establish that station, the 65 foot station and the 33 foot station and complete their dive by gathering algae samples from bottom rocks at the 33 foot and the 9 foot depths.

Photo Credit: NatGeo – Dr. Stan Loeb diver

An important understanding here is that what the scientists are attempting to accomplish here is a replication of a study done back in 1978-1979. When we get all the transects in place, and collect the growth mediums (bricks) we will be able to compare to a baseline of information created over 30 years ago; no one has done this study since. It is very exciting to be a part of this and to see the outcome and comparisons.

The other “diving” aspect of this that is real interesting is that in 1978-1979 the divers doing this initial study completed dives to 200’ with equipment of the day that was no where near as quality as the gear is today. They did not have rebreathers, mixed gas, computers and drysuits with heaters. They had, well… crap! One of the divers from back then was the main student/scientist doing his dissertation, Stan Loeb: now Dr. Stan Loeb and is working out of the University of Kansas. We had the chance to talk with him over the past several months and he told quite a few great stories. I hope he gets to Reno someday so I can buy him a drink and treat him to lunch so he will divulge just how he pulled off these dives in wetsuits, no altitude depth gauges, AIR, single tanks, rubber masks that always leaked (silicone had not been used at the time in mask construction) and other limitations of the day. We are very fortunate to be diving in a time where technology has kept pace keeping us safe and warm.

We exited the water at 4pm and were on our way home by 5.