This past week saw the inauguration of a new partnership between the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Virgin Islands' Department of Planning and Natural Resources (DPNR) for the purpose of maintaining the Coral Reef Early Warning System (CREWS) station located within the Salt River Bay National Historical Park and Ecological Preserve, St. Croix, USVI. This station (see photo at right), whose National Weather Service (NWS) designation is SRBV3, reports meteorological and oceanographic measurements in near-real time, delivering hourly updates by Geostationary Operational Environmental Satellite (GOES) and its data are uploaded to the National Data Buoy Center (NDBC). From NDBC the data are included in the World Meteorological Organization's (WMO) Global Telecommunications System (GTS), making them available for use by national weather services all over the world.
This new collaboration began last August, when DPNR generously provided personnel and boating support for visiting researchers from NOAA's Atlantic Oceanographic and Meteorological Laboratory (AOML) and the University of Miami's (UM) Cooperative Institute for Marine and Atmospheric Studies (CIMAS) during the station's annual instrumentation swapout. Now, thanks to the support of NOAA's Coral Reef Conservation Program (CRCP), DPNR personnel will make regular visits to the Salt River Bay CREWS station to clean and maintain the station's underwater instruments and support structures, as well as to connect a "groundtruth" Conductivity/Temperature (CT) sensor used to track the calibration of the station's permanently installed Conductivity/Temperature/Depth (CTD) sensors.
Meeting on the water this week were Paige Rothenberger and José Sanchez (DPNR), Marlon Hibbert (NOAA/CRCP), Jim Hendee (NOAA/AOML) and Mike Jankulak (UM/CIMAS). The purpose of this operation was threefold: firstly, the Miami team wanted to meet with the St. Croix people in person to give a detailed explanation of the CREWS station maintenance procedures. Secondly, it was decided to do a full instrumentation swapout a few months ahead of schedule since there had been no regular underwater maintenance visits since last summer.
The third and final motivation for this visit was to replace the station's GOES transmitter and its satellite antenna and cable. A typical CREWS station will occasionally drop a transmission due to heavy cloud cover or severe weather conditions, but when averaged over a month's time you would expect to see upwards of 96% of transmissions coming through without errors. Since the last replacement of its transmitter and antenna the St. Croix CREWS station's transmission rate has stayed at 90% success rate or lower, and for the month of February it fell to 76%. These problems may have been caused by loose connections, a too-tight bend in the antenna's co-axial cable, saltwater incursion into the antenna connectors, or any number of other factors. Rather than attempt a prolonged diagnosis of the problem in the field, it was decided to simply replace all transmitter components once again.
On Monday, May 23rd, the DPNR and AOML people met at DPNR's East End Marine Park offices on St. Croix where we assembled all of the equipment needed for the rest of the week and made plans to meet the following morning. Tuesday, all five of us went out to the station where we swapped out three of the four underwater instruments and retrieved all aerial equipment (including the control unit or "brain") for return to land. Wednesday was entirely land-based work as the local memory records were downloaded, the datalogger programming updated, the aerial sensors replaced and rewired, and the entire suite of instruments tested for several hours on land. On Thursday we connected the fourth underwater instrument (the Deep CTD, see below) and the "groundtruth" CT sensor, and reinstalled all aerial sensors and electronics. All sensors were found to be working correctly and before leaving the station we confirmed that satellite transmissions had resumed as well.
Some detailed comments about this work follow:
The Weather Transmitter (WXT), an instrument manufactured by Vaisala that provides wind speed and direction, relative humidity, barometric pressure, air temperature and precipitation readings, is mounted on an aluminum mast above the station. Last August, the bolt holding this mast in place was found to be loose, allowing the mast perhaps 10° of play (see photo at right). On this trip we returned with a power drill and we drilled and tapped a new hole to pin the mast in place more securely. This work was done on Tuesday.
- The platform supporting the GOES antenna is held aloft by two fiberglass poles that slide snugly into two aluminum masts, although there was never anything more than gravity and cable ties holding down this platform in place. On this trip we drilled holes through both support masts and bolted them securely in place (on Thursday).
- Tuesday's operation to replace all four underwater instruments (deep and shallow light sensors, deep and shallow CTDs) hit a snag during the disconnection of the Deep CTD's cable, when one of the cable's four pins broke off and was left in the instrument. Fortunately we had a spare "fish-bite" underwater cable with us so we were able to run the new cable up to the top of the pylon (Tuesday) and deploy the new Deep CTD (Thursday) as planned. Note that this is the second cable failure at this site since station (re-)deployment in 2006, as the Shallow CTD cable failed and was replaced during last August's operations.
Sometime during Tuesday's operations, the lowest aluminum rung (removable ladder rungs that are pushed through the station to allow climbing during these operations) was apparently struck by the edge of the boat and was bent. An attempt to remove this bent rung resulted in the removal of one of the fiberglass rung "inserts" as well (see photo at right), exposing the station's interior foam to the outside. Before leaving on Thursday we plugged these holes with rubber aquaseal. The DPNR maintenance team plans to separate the aluminum rung from the fiberglass insert using tools on land and then reinstall the rung insert at a later date.
Dr. Jim Hendee, the principal investigator of the Integrated Coral Observing Network (ICON) and the creator of the CREWS program, climbed to the top of a CREWS station for the first time and powered on the station once all sensors had been reconnected (see photo at right). It is believed that Dr. Hendee becomes only the fifth person to have ever performed this action on any CREWS station.
The sacrificial zinc (anode) connected to the station's base plate was discovered to be completely dissolved on this visit (Tuesday). Fortunately, the CREWS supplies on St. Croix included a replacement zinc and this was installed during Thursday's dive (see photo at right). Note however that there do not appear to be any sacrificial zincs remaining on any of the eight lengths of support chain.
- Throughout the week, Paige Rothenberger and José Sanchez conducted several dives to inspect and clean the station supports; Marlon Hibbert also did a great deal of cleaning while snorkeling; Jim Hendee and Mike Jankulak conducted our own dive operations. Paige has spoken several times about wanting to obtain diving reciprocity with either NOAA or AAUS, which would allow us all to dive together and could reduce the number of AOML travelers required for these operations. Until this happens, NOAA/UM dive operations will continued to be conducted separately from DPNR operations.
- It is still too early to know whether the transmitter and antenna replacement will have a long-term positive effect on transmitter performance. However, transmissions resumed on Thursday with a higher signal strength than previously and we take this as a hopeful sign.
All in all this week's operations were wildly successful, but the most significant accomplishment is the formal beginning of DPNR's stewardship of the St. Croix CREWS station. The original CREWS station was installed on this site in 2002, and then retrofitted and reinstalled in 2006. Throughout its lifetime it has required costly maintenance contracts with local commercial dive operators. These arrangements have been suboptimal for many reasons and in recent years the costs have become prohibitively high and they had to be abandoned altogether. Thus we are all the more thrilled to have found caretakers from the scientific and conservation community who feel as strongly about this station's mission as we do. This new relationship may foster a new era of scientific collaboration as other researchers can now bring their projects to Salt River Bay and trust that their work will be supported by St. Croix's best scientific minds.
The Miami team sends its heartfelt thanks to NOAA/CRCP and USVI/DPNR, to Paige Rothenberger, José Sanchez, and Marlon Hibbert. We'd also like to offer a special shout-out to CRCP's Dana Wusinich-Mendez who dove into her enormous rolodex last year and emerged with a half-dozen contact names for potential collaborations in St. Croix -- those names led directly to the present collaboration.
In this photo are pictured, from left to right, Jim Hendee, José Sanchez, Paige Rothenberger and Marlon Hibbert (not shown: Mike Jankulak).[Photo credits: Paige Rothenberger (Jim on pylon), Jim Hendee (base plate zinc), Mike Jankulak (all others).]
