It has been a busy year and we have been diving nearly every week to keep up with all the projects in the lab. Last week we dove Sulphur Springs to exchange some instrumentation that had been in the spring conduit since November and to get some much needed samples. This week we went back to Hospital Hole. For the first dive we dropped a bucket of cement as a weight tied to a line that connected to a surface buoy. You can see the buoy in the photo below. It immediately attracted all the manatees. Bobby and Dr Garey went down the line, measuring the distance from the line to the wall using a hand held underwater sonar device. We determined that the hole is about 50 ft across at the top, and about 130 ft across at the bottom. We removed the bucket and buoy at the end of the dive. On a second dive, we did some exploratory diving, documenting many of the smaller vents and odd patches of biofilm. It was a cold day and Madison did a great job providing boat support.
We went to Hospital Hole to collect samples for Madison's project. It took all day as Roger's Park is still closed and we had to launch the boat at an alternate site several miles down river. Bobby and Dr. Garey did three dives, collecting water, biofilm and sediment samples from a number of locations at depths of 40-130 feet deep. Madison did boat support and took care of all the samples. The manatees were in full force. In the winter they leave the chilly water of the Gulf of Mexico and come up the spring-fed rivers where the water is always 74 degrees F. Usually in the winter there are several families of manatees present around Hospital Hole. Back at the lab, everyone had a very late night doing all the water chemistry measurements.
Our last dive of the calendar year was to Jewfish Sink, a deep sinkhole located about a km offshore, just south of Aripeka, FL. We left the lab around 9 AM and arrived at the Aripeka boat ramp at about 10:30. The tide was low so we had to be careful maneuvering out the channel. It was slightly foggy at first and we saw a terrific fog bow just after we left the ramp. It became a beautiful day with glassy smooth water and we saw a couple of sea turtles and some small bonnet head sharks along the way. We anchored at the hole and Bobby and Dr. Garey suited up with Vickie doing boat support. Gulf water was 65 degrees F and. the air temperature was about 75 so a bit chilly for us Floridians. The first dive was along the wall down to the anaerobic zone where we collected water and biofilm samples at about 110 ft. The hole is about 18 ft across at the surface but gradually widens to about 200 ft wide, so the divers had to swim back under the overhead as they headed toward the wall. After a bit of decompression and a good surface interval, the second dive followed a line we had left on an earlier dive. This line terminates on the debris mound at about 160 ft where we collected sediment for Madison's experiments. At that depth there is no light, no oxygen and a lot of hydrogen sulfide. All went well and we had a great trip back to the dock, and again, a long night processing samples.
We visited Double Keyhole Spring to harvest the first set of microcosms for Vickie's senior thesis carbonate dissolution project. We left the lab at 7 AM and arrived at the Aripeka FL boat ramp at 8:15. It was a beautiful calm cool day. We launched the boat and motored to the Spring with a bunch of dolphins riding our bow wave part of the way. We arrived around 9:30 and were in the water a little after 10 AM. High tide was at noon, and we have to collect water samples an hour or two prior to high tide as the tide can cause the spring to reverse flow. We need to be sure the water we collect is from the spring and is not Gulf water brought in with the high tide. The goal was to bring one set of 12 microcosms out along with a full set of water samples, sediment samples, and microbial mat samples from the wall of the conduit. The microcosms are pvc tubes containing crushed limestone. It took Bobby and Dr. Garey a little over an hour to collect all the samples but took all night for the lab members to process them all once we got back to the lab.
The lab visited Hospital Hole in the Weeki Wachee River to obtain samples for Madison. Dr. Garey and Bobby made the dives with Madison in charge of the boat and sampling strategy and sample processing. Hospital Hole is a highly stratified sink located under the Weeki Wachee River near Weeki Wachee Gardens in Florida. It takes about 90 minutes to get there from USF. Our normal boat launch site is Roger's park which was closed for some parking lot resurfacing so we had to go to another park further downstream. Once we launched it took about 30 minutes to reach the site. We hit the water around 1:30 PM and made a series of dives. We collected water from the overlying river, from the hypoxic zone, an active vent in the hypoxic zone, the chemocline, and the deeper anoxic zone. We also collected biofilm from some zones and sediment from the bottom. In total we filled about 50 sample bottles. It was getting dark when we headed back and there was a beautiful sunset along the river. Then the students pulled an all nighter in the lab getting all the samples processed and all the tests run.
Most of the lab came to the GSA meetings. Dr. Garey, Madison, Christina, Bobby, Vickie. All made the trip. Dr. Garey and Christina made oral presentations on Sunday, while Madison, Bobby and Vickie did poster presentations. We visited Pike's Market, went on a Ferris wheel, saw the Space Needle, and wandered around beautiful downtown Seattle. The first day was rainy but it has been cool and sunny Sunday and Monday. We met a lot of people doing interesting research in karst.
We visited Double Keyhole Spring located on the west coast of Florida. The Spring discharges into the Gulf and we have published several papers describing how this spring creates an "invisible" estuary that is a sensitive ecosystem supporting juvenile fish. Vicki is running a carbonate dissolution experiment begun by former student Rachel (now graduated). It is a long term measurement of how fast carbonate dissolves in a variety of conditions. This experiment is in its third year. Carbonate dissolution is what enlarges conduits and creates sinkholes and other karst features over time.
We drove to Aripeka, put the boat in the water and motored several miles to Double Keyhole Spring. Bobby and Dr. Garey made the dive with Vicki there to help with the boat and handle the samples we collected. The experiment is set up in a shallow conduit that is about 8 feet in diameter back in about 200 ft at a depth of 25 ft. We collected one set of microcosms (pvc tubes with sorted limestone gravel) and also collected biofilm from rock surface and from the pvc frame that holds the microcosms. Finally, we collected sediment and water samples. It was a lot of samples and we did it in two 45 minute dives. Then back to the boat, back to the dock, and back to USF and another long night of sample analyses with all the lab members pitching in.
Bobby and Dr. Garey made their first post-hurricane Irma dive on Tuesday October 3rd. The flow was as strong as we have encountered and it took a major effort to get in, especially with all of the sampling gear and instrumentation we had to carry. Luckily there is a thick rope tied of inside the cave along the right side as you enter, which helps when you can't simply swim in. Once we got in to where the cave opens up, the current drops off and we proceeded to our instrument station about 300 ft in at a depth of 80 ft. We swapped out the ADV and Hydrolab and went to our 90 ft deep sampling station about 20 feet further in the cave. There we collected water, sediment and biofilm samples. Total dive time was about an hour. Then the students pulled another long night analyzing all the samples. It is a lot of work on dive day!
We visited Hospital Hole to collect samples for Madison's project on September 28th. Bobby and Dr. Garey went as divers while Madison and Chelsea did boat support, surface sampling and took care of all the samples. It was a beautiful Fall day. Hospital Hole is a deep sink (140 ft deep) located in the Weeki Wachee River in Florida. Normally the deep water is anoxic with the walls at the deepest point covered in biofilm. This soon after Hurricane Irma there had been a change and none of the normal biofilm was found in the deepest part. However, on the way up we passed a normally inactive vent that was discharging water at a tremendous rate and it was surrounded by various types of biofilm. Luckily we had spare sample bottles and made a second dive to collect water and biofilm samples from the vent. All went well, we returned to the lab and all the students were up much of the night processing all the samples. We expect some very interesting results.
On Tuesday, we visited Jewfish Sink, a site we have been studying since 2003. It is located in the Gulf of Mexico about half a mile offshore, a mile south of Aripeka, FL. The sink is about 200 ft deep. See Garman et al. 2005 and 2011 for details. The purpose of the dive was to collect sediment, water and wall biofilm samples from the deeper anaerobic portion for Madison and Chelsea's projects. Bobby and I made two dives. The first was down the center of the sink to the debris mound at 154 feet where we collected sediment. After a one hour surface interval we made a second dive along the eastern wall to 112 feet where the biofilm is particularly thick and we were able to collect plenty of biofilm with large plastic syringes. We also collected water column samples. Although the surface water is well over 80 degrees this time of year, the deep water in the sink was only 66 degrees so we were glad to get into the warmer water for decompression. One of the things we want to see is how similar the microbial communities in this offshore sink might be compared to those in similar saltwater coastal sinks found on shore. Madison and Chelsea provided boat support. It was a beautiful day, glassy smooth with no wind. There were dozens of dolphins feeding in the area and we saw a number of large rays and sea turtles as well. We left the lab at 8 in the morning and returned around 6 at night. All the other students were in the lab when we returned to help process the samples well into the night. It was a fantastic day and a successful trip!
As I write this, we are waiting to see where Hurricane Irma will be heading as it will likely have an effect on the lab's activities next week. Hopefully all will be well.
Bobby Scharping and Dr. Garey completed a dive in Hudson Grotto yesterday. The goal was to bring a full set of samples from the deep section (132 ft deep). It was Bobby's first scientific dive using a rebreather. We dropped down to the bottom of the grotto and headed to the south wall, and turned left until we found a section of wall with extensive microbial mat. Although the surface water was 89 degrees, the bottom was 74 degrees in this anchialine system. We collected a water sample for stable isotopes, and then filled 9 syringes with microbial mat samples from the wall. After that we moved a few meters away to avoid the sediment we disturbed and collected water column samples, and finally, some sediment samples. We spent another 30 minutes or so decompressing and making our way to the surface. Once we arrived back in the lab, Madison, Vickie and others were there to process the samples and carry out the chemistry tests and DNA extractions. So it was another great day!
Thanks to graduate student Christina Moss, we have a new Garey Lab website. We are trying out a blog to keep interested folks up to date on the lab activities. Now in early August we are planning a dive next week to Hudson Grotto to collect some deep microbial mat samples for Madison Davis' project. Other than that, lab members are catching up on LH-PCR and qPCR runs and analyzing some Illumina sequence datasets collected earlier this year. I include a photo of a lab meeting in the office taken late last year.