Field
- Most biological surveys of coral-reef environments are limited to depths accessible by
conventional SCUBA gear; typically about 30-40 m. Over the past two decades, the
emergence of so-called “Technical Diving”, which incorporates advanced diving equipment
and techniques (e.g. closed-circuit rebreathers, helium-based breathing mixtures, enriched
oxygen breathing gas for accelerated decompression, etc.) has allowed highly trained
marine biologists access to depths of 50-150m for scientific research. Initial surveys
conducted by Pyle and associates in Hawaii, the Cook Islands, Palau, Fiji, Papua New
Guinea, Samoa, Taiwan, Line Islands, Vanuatu, and (most recently) across the Caroline
Islands, has revealed a consistent pattern of rich biodiversity at these depths below the
more traditionally-surveyed shallow coral reefs. This habitat, variously referred to as “deep
coral reefs”, the “coral-reef Twilight Zone”, or “Mesophotic Coral Reef Ecosystems”, is
characterized by organisms typically associated with shallow coral-reef habitats (e.g., soft
corals, sponges and other reef-associated sessile invertebrates, and fishes belonging to
coral-reef fish families), a high proportion of which represent undescribed species. Through
these initial surveys, it has become apparent that the depth-zone traditionally surveyed with
conventional SCUBA represents only the upper 30% of the overall coral-reef ecosystem; the
deeper 70% of which remains mostly unexplored, and poorly understood. The non-profit
Association for Marine Exploration (AME;
www.marineexploration.org) was established
specifically to facilitate scientific exploration of undersea habitats that are otherwise
inaccessible to divers using conventional SCUBA. Since its inception in 2003, AME has
organized or participated collaboratively in five major expeditions focused on collecting
voucher specimens and tissue samples of fishes and invertebrates from coral-reef habitat at
depths of 50-150m. AME divers use the most advanced electronically-controlled closedcircuit
rebreathers available, and have perfected diving and collecting techniques that allow
efficientspecimen acquisition with minimal impact to the reef infrastructure, within very
conservative margins for safety. Each diver uses a Cis-Lunar MK-5 rebreather and carries
five separate gas supplies (primary and secondary oxygen, air for blending enriched airnitrox
during decompression, heliox for blending trimix, and a large-capacity trimix [helium/
nitrogen/oxygen] cylinder for emergency bailout). After more than two thousand rebreather
dives by AME divers, there has never been a need for a full bailout. Nevertheless, all dives
are conducted with access to a full open-circuit bailout pathway back to the surface, using
different techniques depending on specific conditions and circumstances. In-water
Recompression (IWR) has proven to be an extremely effective emergency response to
symptoms or suspected symptoms of decompression sickness (DCI), with complete success
in the very rare circumstances when it has been utilized (never during an AME project –
only in the previous experience of AME divers). Fish specimens are usually collected with
custom-built monofilament hand-nets, sometimes with barrier nets. Chemical anesthetics
and ichthyocides are sometimes used when circumstances are appropriate and proper
permits are available, but always with the utmost care to prevent bycatch or other damage
to the reef habitat. Small fishes and invertebrates are collected with the aid of a custombuilt
Electric Underwater Vacuum Cleaner (EUVC), which proved extremely effective during
an expedition to Vanuatu in 2006. All dives and most observed species are documented by
Hi-Definition video taken by one of the deep divers who is dedicated for this function. Such
video has proven valuable for documenting additional species that escape collection, and for
documenting the general habitat characteristics. For this project, we propose to contract
with AME to acquire specimens of selected organisms (fishes and marine invertebrates)
from depths of 50-150m at selected sites around Moorea. Two separate trips are planned –
approximately three weeks each – to allow diving in different areas with different optimal
seasons (swell conditions). Voucher specimens will be brought to the surface,
photographed, and processed following preservation protocols appropriate to each kind of
organism. Tissue samples will be extracted from each specimen for sequencing and
analysis, and vouchers will deposited in appropriate institutional collections. AME will be
responsible for all diving equipment and personnel involved with deepdiving activities,
except possibly for support divers (if available locally). One deep dive per day is conducted
by a team of 3-4 deep divers, with 1-2 support divers in the boat. Dives typically last from
3-7 hours each, depending on depth and duration. The maximum depth accessible by AME
divers is approximately 150m, but most dives are made in the range of 100-120m, and
some are focused on depths of 50-100m. Typically one of the deep-diving team is dedicated
to capturing Hi-Def video of the habitat and specific organisms, while other deep divers are
focused on collecting with either nets or the EUVC. Bottom times typically range from 30-60
minutes at deeper depths, and 60-90 minutes for intermediate depths; with decompression
times lasting from 2-6 hours. Ideally, decompression is conducted along a reef slope or
dropoff, but can also be conducted in mid-water following a line to the surface. Depending
on specific circumstances, deep divers may either drag a line with afloat on the surface, or
follow an underwater line or natural contour down to depth, and then deploy an inflatable
surface float upon ascent. Mechanisms for communication among deep divers, and between
the deep-diving team and the surface-support team depend on specific circumstances, and
are established well in advanced of dive trips. All personnel involved with the deep diving
activities are fully briefed on emergency protocols, including IWR.
Laboratory
- The protocols for fish were well established in the pilot MBP. Pyle's AME team
has extensive experience archiving the voucher specimens, capturing the associated
metadata, and identifying the species. A smaller tissue sampling and archival team will
accompany the AME group onsite for the processing of genetic material and stabilization of
the marine invertebrate component. Serge Planes will coordinate the tissue team and the
biocode technicians will handle the material derived from the EUVC. All samples will be
extracted at Gump and sequenced at LAB.
Timeline:
Two field trips will be made during 2009 (probably July and December).
