TECHNICAL SCIENTIFIC DIVING WORKSHOP DIVE PROJECTS
EILAT, ISRAEL JUNE 20-25, 2010
Dive Projects at the Technical Scientific Diving workshop in June 2010–04–19
In-situ photosynthetic measurements in a
seagrass meadow along a 50 m depth/light gradient
Project leader: Yoni Sharon; PhD candidate at the Tel Aviv University
The macro-benthic community of the Red Sea includes diverse auto-phototrophic organisms, dominating by
hermatypic corals, macro algae and seagrasses. The seagrass Halophila stipulacea grows in the Gulf of Aqaba
(northern Red Sea) from the intertidal to depths of ~50 m. Along that depth gradient, there is more than an order
of magnitude difference in irradiance and the spectrum narrows to mainly blue light with the absence of red and
UV wavelengths [at the depth limit of this plant]. In a prolonged study during the last 4 years we have found
different physiological adaptations featured by this seagrass, which may explain its ability to grow along an
impressive depth (light) gradient, down to the twilight zone.
In order to explore one physiological adaptation, we'll use an in-situ PAM fluorometer (Diving PAM, Walz,
Germany) to conduct rapid light curves under natural conditions. In this project we'll conduct a single dive to 50
m with a bottom time of 40 min, using a closed circle re-breather.
Underwater Pneumatic Coring: Technical Scientific Diving Workshop
Project leader: Dr Beverly Goodman; Haifa University
In the uppershelf marine environment, it is common to encounter sandy sediments. For the scientist who is
interested in fine resolution sampling, larger drilling machinery does not preserve the finer structure of the
samples, gravity or piston cores cannot penetrate the horizon, and vibracoring tends to distort the materials.
Percussion, or hammering, is an excellent option for achieving good penetration depth with least disturbance of
the sample. To this end, a diver-operated pneumatic hammering system was developed for use in the upper shelf
zone.
This is a relatively shallow (30-35m) yet long and fairly complex dive from the IUI research vessel. Dive leaders
(but not necesseraly the participants) will use rebreathers to be able to complete their mission. Workshop
attendees who choose to join this project will take a turn on the pneumatic hammer. Divers must wear hoods as
ear protection and observe the worksite at a distance (to be explained at the briefing). Once the rig is erected
participants will rotate into the worksite to operate the hammer. The work will be monitored by an ROV such that
it will be viewable from the deck. The dive to the site will occur midway between the construction of the worksite
and the core removal. All divers will return to the ship before the final stages of the core extraction and will be
able to watch the activities topside from the ROV monitor.
Drilling into a fossil fringing reef at water depth of ~65 meters
Project leader: Gal Hartman; PhD candidate at the Haifa University
A fossil fringing reef was revealed along the northern shelf of the Gulf of Eilat/Aqaba during a geophysical study.
This reef is one of six sequences of fringing reefs generation that was interpreted from high resolution seismic
data. The reef is traced at water depth of ~65 m and has a major role in the understanding the stratigraphy of the
northern shelf. The reef is cross-cut by a major segment of the Dead Sea Transform and has a sinistral offset of
~30 meters. Sampling and dating the reef will improve our understanding of the chronostratigraphy of the
northern shelf and the mechanisms of the Dead Sea Transform in the region.
In the dive we plan to obtain a core from the fossil reef using hand core driller. The participates will view the
work on site and expected to observe the general structure of the fringing reef. The maximum depth of the dive
will be 65 m with maximum bottom time of 20 minutes. All participants must be experienced and certified trimix
divers. We will appreciate presence of scientists with affinity to marine geology or reef structures and evolution.
Coral photosynthesis in the mesophotic zone – experimental design.
Project leader: Dr. Dan Tchernov; Haifa University
We plan to establish a long term transplantation experiment to try and establish acclimatization and adaptation
traits in the holobiont.
We will transplant 10 colonies of shallow(3m) Stylophora p. in three stages to 65 m depth. We will transplant 10
Stylophora p. colonies to 45 m depth and after careful monitoring we will start to gradually taking them up over
the next months. We shall also transplant 5 deep (65m) colonies to a neighboring site at the same depth as a
control. Another two sets are planned : 5 shallow colonies will be transplanted to the space beneath the IUI peer,
and 5 more will be incubated on shore under a blue 467 nm narrow band filter. We will also try to shine
underwater red light on 5 deep colonies (65m) with red L.E.D’s powered by a battery pack and try to shine extra
blue light on 5 deep colonies (the same L.E.D system).
We will need very small table–like stands for the colonies, two for ten small colonies, and six more for five
colonies each.
We will conduct several dives according to the progress of the experiment but basically:
1.
2.
3.
Set-up deep collection dive and initial transplants.
Light set-up dive 65m
Sampling deep dive in the end of the work shop.
iui@vms.huji.ac.il
Fish sampling in the mesophotic reef
Project leader: Dr Eran Brokovich; Tel Aviv University
This project is a part of a research for studying the biodiversity of mesophotic coral reefs. There is very little work
on the cryptic fish fauna in our area in general and in depths greater than 30 m in particular. These small cryptic
fish form the base of the food chain for some of the coral reef fishes living in mesophotic reefs. Some of them are
already suspected as new records or new species.
Cryptic fishes are extremely abundant and visual methods will only sample ca. 30% of the actual species and
individuals.
In this project we will use technical diving to sample fish for quantitative assessment of cryptic species.
For this end we shall use Rotenon, a natural poison made from the roots of a South American plant. In deep
diving when every minute counts it is actually the only method worth considering. We start by marking the
circumference of the study area apply Rotenon and collect the fish.
Rotenon starts affecting the fish within 10-15 min and is active for about 40 minutes before it its diluted to
insignificant amounts (depends on the current).
The poisoned fish will be collected into jars, brought up to the surface for identification, preserved in ethanol and
delivered to the national fish collection at the Tel Aviv University.
The dive will be to 50 m depth. Project leaders will use rebreathers to complete the project. Participants can use
OC diving gear and stay according to their dive plan.