Memphis Project Annual Report:
July 2002 – July 2003
Submitted to:
Broward
County Department of Planning and Environmental Protection
218 SW First Avenue
Fort Lauderdale, Florida 33301
Prepared by:
Richard E. Spieler, Ph.D. and
T. Patrick Quinn, M.S.,
Oceanographic Center
Nova Southeastern University
8000 North Ocean Drive
Davie, Florida 33004
Submitted by:
_________________________
Date: _________________
Richard E. Spieler, Ph.D.
EXECUTIVE SUMMARY
The United States nuclear submarine MEMPHIS grounded in approximately 10 m of water on a southeastern Florida coral reef off Broward County in February 1993. This grounding caused extensive physical and biological damage to the reef substrate and to the coral community. As part of a mitigation plan, in July 2000 a three-year experimental restoration project was initiated. This is a report of the third year of that project. However, the annual reports are cumulative in text, data and analyses and therefore this report also contains information from the first two year’s work.
In order to gain insight into optimal methodology for restoring corals to a damage site, the project compares settlement, growth, and survival rate of corals amongst artificial reefs treated with potential attractants (iron, quarry rock, coral transplants) and no-attractant controls. Further, in order to examine appropriate structural design for restoration, the reefs are divided into four treatments of structural complexity. This allows the determination of the interactive effects of four different fish communities on coral settlement and growth. In addition, the work investigates the potential role of microbial biofilms as settlement precursors. The transplant treatments are identical replicates (same numbers of each species). This will allow the determination of species specific differential survival and growth rates of coral transplants. Finally, the four complexity treatments will yield insight into fish community restoration methodology (the hypothesis here is that multiple refuge size is required for a diverse coral reef community).
The experimental design consists of 160 small (1.13 m) Reef Ballsä organized into 40, 4-module reef units (quads) each in a square configuration with 3-m sides. Each quad has Reef Balls with the four attractant treatments, one Reef Ball per attractant (iron, quarry rock, coral transplants, or only concrete). Each Reef Ball has two standardized settlement plates incorporating the attractant treatment of the Reef Ball. The 40 quads are divided into four different levels of structural complexity. One set of 10 quads has the void spaces of all the Reef Balls empty. One set has the void spaces of all filled with structure offering small refuge (plastic caging). Another set of 10 has the void spaces of all filled with large refuge (concrete block). The final set of 10 quads is mixed and has one Reef Ball empty, one with large refuge, and the last two with small refuge.
One hundred and sixty Reef Balls, 433 settlement plates, and 1500 biofilm discs were constructed July-August 2000. The Reef Balls were deployed in November 2000. However, many Reef Balls were not deployed on designated sites and extensive delay to the research was incurred due to the time needed to adjust the positions. The final arrangement was achieved in June 2001. Settlement plates and biofilm discs were coated with concrete and attractants (iron filings, calcium carbonate sand) or concrete without attractants (controls) in July 2001 and were deployed in August 2001. Quarterly data collection was initiated in October 2001. In excess of 670 individual SCUBA dives have been made to date.
The biofilm discs were removed at 1, 3, 7, 14, 21 and 60 day intervals and examined microscopically for biofouling. The control discs and those incorporating the calcium carbonate did not differ in the settlement rate of bacteria or diatoms. However, the discs with iron filings had a significantly slower settling rate than both the calcium carbonate and control discs.
In August 2002, a study was also initiated to examine the potential for a red coralline alga (Hydrolithon boergesenii) to act as an attractant for coral settlement on restoration concrete structure. Settlement plates were formed into tent shaped modules by the addition of a concrete base and deployed at four sites, eight modules per site. One site was on a field of coral rubble with abundant H. boergesenii. A second, nearby, site on a sand field was selected as control, and cleaned of incidental algae coated rubble for a 10 m radius. The third site was adjacent to hard bottom on a rubble field with abundant H. boergesenii. Site four, the control for #3, was located on hardbottom with abundant hard corals but which lacked H. boergesenii or abundant rubble. Our hypothesis is: if H. boergesenii provides a coral attractant, more hard coral should recruit to plates surrounded by the algae than in control areas without the presence of the algae. After 12 months no coral recruits were macroscopically visible on settlement plates.
Caging and concrete fill was added to the Reef Balls in May-July 2001 to acquire differential complexity. As hypothesized, after 12 months, there were already different fish assemblages associated with the differing fill. At 24 months, for total abundance of fish, the empty reef balls did not differ from those with mixed fill however both these treatments were significantly less than either small or large fill which did not differ from each other. With species richness, the empty reef balls had fewer species than those with small fill which, in turn, had fewer than either mixed or large fill treatments which did not differ from each other. An understanding of the potential interaction of these differing assemblages with coral recruitment and mortality awaits photographic analysis of the settlement plates.
Coral species were selected for transplantation (Montastrea cavernosa and Meandrina meandrites) and donor colonies located. The first four transplants were drilled out of donor colonies using a hydraulic drill in March 2001. The holes in the donor corals were filled with concrete plugs and before-and-after photographs were taken of each site. The cores were then taken to the Reef Ball site and epoxyed into the appropriate Reef Balls. The last of the 80 transplants were completed in July 2001. After 23 months, 100% of the M. cavernosa and 27.5% of the M. meandrites transplants maintained their original tissue surface area or showed evidence of an increase in surface area. The remaining 72.5% of the M. meandrites transplants have shown varying degrees of partial tissue mortality. The donor colonies have experienced 100% colony survival. Although there has been some growth onto the plugs, none of the core hole sites have regenerated tissue over an entire concrete plug. However, there has been little tissue die back from the plug sites and so complete regeneration remains probable. Clearly, the species-specific differences in transplant growth and mortality, noted in this study, indicate that species selection must be an important consideration in future coral reef restoration efforts.
TABLE OF CONTENTS
EXECUTIVE
SUMMARY................................................................................. 2
TABLE OF
CONTENTS..................................................................................... 4
INTRODUCTION.................................................................................................... 5
METHODS AND MATERIALS...................................................................... 5
Experimental Design............................................................................... 5
Reef Ball Construction and Deployment.................................................. 6
Coral Transplantation............................................................................. 7
Complexity Fill...................................................................................... 8
Coral Attractants.................................................................................... 8
Biofilm Research................................................................................... 8
Red Algae as Coral Attractant Study....................................................... 9
RESULTS................................................................................................................... 10
Coral Transplants................................................................................. 10
Biofilm................................................................................................ 12
Fish Assemblages................................................................................ 13
Settlement Plates.................................................................................. 13
Red Algae as Coral
Attractant Study..................................................... 13
DISCUSSION........................................................................................................... 14
APPENDIX............................................................................................................... 15
Memphis Project Timeline.................................................................... 16
Final DGPS coordinates of the Reef Ball Quads.................................... 17
Map of Second Reef Depicting Site of Donor and Control Corals.......... 18
Memphis Restoration, 1st Quarterly Report........................................... 19
Memphis Restoration, 2nd Quarterly Report......................................... 19
Memphis Restoration, 3rd Quarterly Report.......................................... 21
Memphis Restoration, 4th Quarterly Report.......................................... 25
Memphis Restoration, 5th Quarterly Report.......................................... 30
Memphis Restoration, 6th Quarterly Report.......................................... 34
Memphis Restoration, 7th Quarterly Report.......................................... 36
Memphis Restoration, 8th Quarterly Report.......................................... 38
Memphis Restoration,
9th Quarterly Report.......................................... 41
Memphis Restoration,
10th Quarterly Report......................................... 43
Memphis Restoration,
11th Quarterly Report......................................... 44
Descriptive Statistics: Species Richness Per Treatment.......................... 46
Descriptive Statistics: Fish Abundance Per Treatment............................ 47
Analysis of the Initial Microfouling Communities................................... 48
Scientific Presentations......................................................................... 75
INTRODUCTION
The United States nuclear submarine MEMPHIS grounded in approximately 10 m of water on a southeastern Florida coral reef off Broward County in February 1993. This grounding caused extensive physical and biological damage to the reef substrate and to the coral community. As part of a mitigation plan, in July 2000 a three-year experimental restoration project was initiated. However, because of technical difficulties that delayed the initiation of data collection for almost a year, it was decided to continue the study for an additional 12 months. This is a report of the third year of the project. However, the annual reports are cumulative in text, data and analyses and therefore this report also contains information from the first two year’s work. A breakdown of the annual task accomplishment is provided in the project timeline and the quarterly reports (see Appendix).
In order to gain insight into optimal methodology for restoring corals to a damage site, the project compares settlement, growth, and survival rate of corals amongst artificial reefs treated with potential attractants (iron, quarry rock, transplants, and no-attractant controls). Further, in order to examine appropriate structural design for restoration, the reefs are divided into four treatments of structural complexity. This allows the determination of the interactive effects of four different fish communities on coral settlement and growth. The transplant treatments are identical replicates (same numbers of each species). This will allow the determination of species specific differential survival and growth rates of coral transplants. Finally, the four complexity treatments will yield insight into fish community restoration methodology (the hypothesis here is that multiple refuge size is required for a diverse coral reef community). In addition, two sub-studies investigate the potential role of microbial biofilms as settlement precursors and the potential of a coralline red algae (Hydrolithon boergesenii) to act as an attractant to restoration-concrete structure.
METHODS AND MATERIALS
Experimental Design
The experimental design consists of 160 small (1.13 m) Reef Ballsä organized into 40, 4-module reef units (quads) each in a square configuration with 3-m sides. Each quad has Reef Balls with the four-attractant treatments, one Reef Ball per attractant (iron, quarry rock, coral transplants, or only concrete). Each Reef Ball has two standardized settlement plates incorporating the attractant treatment of the Reef Ball. The 40 quads are divided into four different levels of structural complexity. One set of 10 quads has the void spaces of all the Reef Balls empty. One set has the void spaces of all filled with structure offering small refuge (plastic caging). Another set of 10 has the void spaces of all filled with large refuge (concrete block). The final set of 10 quads is mixed and has one Reef Ball empty, one with large refuge, and the last two with small refuge. In addition, biofilm discs were attached on Reef Balls adjacent the main study area. These discs were removed at 1, 3, 7, 14, 21 and 60-day intervals and examined for biofouling.
Reef Ball Construction
and Deployment
Construction of Reef Balls began on July 31, 2000 and was completed August 18, 2000. The construction involved a total of 494 labor hours and concluded with the completion of 168 Reef Balls (suitable for deployment), 433 settlement plates and 1500 biofilm discs. The settlement plates and biofilm discs were constructed at this time to ensure the concrete mixture was the same for Reef Balls and attractant structures. Approximately 40 additional Reef Balls were constructed that were rejected due to flaws. The Reef Balls and settlement plates were stored at Nova Southeastern University’s Oceanographic Center (NSUOC) until deployment.
On September 12, 2000 NSUOC personnel surveyed the deployment site to map the reef edge and search for hard bottom between the reefs. Deployment of the Reef Balls took place on November 17, 2000. The first quad (group of four Reef Balls) was deployed at approximately 0700 hrs and the 40th quad was deployed at approximately 1420 hrs.
NSUOC personnel attempted to map the grid of quads from November 27, 2000 to January 4, 2001 using SCUBA divers with slates. After six dives, the Reef Balls did not appear to be in a recognizable pattern and eight quads could not be found. To obtain a more detailed map and find the missing quads, NSUOC personnel chose a day (January 6, 2001) with very good surface-to-bottom visibility and live-boated over the grid area. DGPS coordinates were recorded each time the boat passed over a quad. The coordinates were then entered into a program written specifically for the purpose of charting the grid. Divers then swam the grid with a laminated hard-copy of the chart and signaled the boat each time they were at a quad. The signal was to submerge the dive flag and then hold the flag directly over the quad. The boat came up to the flag, paused and the DGPS coordinate was recorded. This was accomplished on January 11-12, 2001 and the missing eight quads were found. The coordinates were reentered into the charting program to acquire an accurate map of the grid area. It was determined that approximately 16 quads would need to be repositioned to approach the desired 30-meter separation. In addition, a number of individual Reef Balls within quads were not spaced correctly. NSUOC personnel started repositioning the Reef Balls on February 21, 2001. This involved 2-3 divers and 4-5 100 lb. lift bags for each Reef Ball. The bags were attached to a Reef Ball, inflated and the divers maneuvered the Reef Ball to obtain the correct spacing. This work was completed on February 21, 2001; however an additional two Reef Balls were later found that required correct spacing (Figure 1). Broward County DPEP and NSUOC personnel started moving quads for the desired 30 meter separation distance on March 3, 2001 and completed the task on June 5, 2001. Approximately 29 dives were made to move 80 Reef Balls. There were two sets of quads that still did not have the full 30-meter separation distance but it was decided to take this into account, if necessary, in statistical evaluations and proceed with the study. Each quad is labeled with a 3x5 inch plastic laminated tag containing the quad’s specific number. The DGPS coordinates and label numbers are listed in the appendix.
Coral Transplantation
From January 26 to February 8, 2001, 89 concrete plugs were made to fill the holes in donor corals that would be formed by removing the drilled transplant coral cores. On April 5, 2001 the plugs were shortened to better fit the donor corals. The coral transplantation work began on September 12, 2000 with a dive on the second reef, near the Memphis grounding site, to assess the area for suitable species and numbers of donor corals. Montastrea cavernosa and Meandrina meandrites were selected as transplant species due to availability and colony size. The first four colonies were drilled using a Stanley Hydraulic drill on March 14, 2001. The holes in the donor corals were filled with concrete plugs and before-and-after photographs were taken. The cores were then taken to the Reef Ball site and epoxyed into the appropriate Reef Balls (Figure 2).
Corals for donors and controls (non-drilled colonies) were mapped (see Appendix), tagged and photographed from April 2, 2001 through June 11, 2001. Requirements for controls were specimens of the appropriate size for both donors and transplants. The trigger mechanism on the drill malfunctioned in April and the drill was taken in for service. Technical problems continued with the drill finally resulting in a new drill being sent to NSUOC on June 5, 2001. Drilling of donor corals resumed on June 15, 2001 and was completed on July 6, 2001. Coral cores were placed in the appropriate Reef Balls the day each core was drilled. The cores were photographed and secured into the Reef Balls with epoxy from June 19 to June 24, 2001. Donor corals were photographed and plugged from June 24 to July 10, 2001. Approximately 61 dives were made to setup the coral transplantation and monitoring aspects of the project.
Photographs, taken at quarterly intervals, are being used to determine coral growth over the course of the study. The first complete monitoring session for 2001 was June-July. Monitoring consisted of a photographic (slide) image of each study coral. Photographic images of the transplants, the core hole sites (in the donor corals), and the small controls are recorded using a Nikonos V camera with a 28 mm lens and close up kit. Photographic images of the entire donor colonies and the large control colonies are recorded using a Nikonos V camera and a 20 mm lens with a 0.75 m2 PVC framer marked in 10 cm increments. The resulting slide images are scanned using a Hewlett Packard Photosmart S20 slide scanner. SigmaScan Pro4 image analysis software (Jandel Scientific Corporation) is being used for the analysis of the slide data. Individual slides were digitized then calibrated using a ruler, included in the image, and measured in order to determine tissue growth or retreat over time. This photographic technique has allowed growth to be measured continually using an accurate and non-invasive methodology. This technique is one of the few monitoring methods in which the coral colony is not sacrificed and in which changes in planar growth in two dimensions can be accurately assessed.
Complexity Fill
Plastic cage material and cinder block were used for the small fill and large fill respectively. Approximately 50 m of plastic cage material (2 cm grid) were cut into triangular shapes, rolled into cones and tie-wrapped into the Reef Balls by divers. The cinder blocks were dropped overboard at the location of each quad assigned to have large fill. Divers then collected the block and placed them inside the Reef Balls. This work began on May 7, 2001 and was completed on July 6, 2001.
Coral Attractants
Approximately 320 settlement plates were coated with the appropriate attractants (iron granules, quarry rock, or plain concrete) and cemented onto the Reef Balls in August 2001.
Biofilm Research
Approximately 1500 biofilm discs were made during the Reef Ball’s construction of the same concrete mix. The discs were coated with the appropriate attractants (iron granules, quarry rock, or plain concrete) and stored at NSUOC. The discs were attached in an array on extra Reef Balls deployed outside, but adjacent to, the main study area in August 2001. A preliminary technique study of biofilm attachment to the discs was accomplished in November 2001 and the results were presented at American Society Limnology and Oceanography Conference 2001 in Albuquerque, NM (Appendix). The biofilm discs were collected over a two-month period and analyzed. Data analysis was completed July 2002. A full discussion of the biofilm methods is included in an attached report (Appendix).
Red Algae as Coral
Attractant Study
A study was initiated to examine the potential for using a red coralline alga (Hydrolithon boergesenii) to enhance recruitment to restoration structure. Settlement plates, made in July-August 2000 with the other settlement plates used on the Reef Balls, were formed into tent shaped modules by the addition of a concrete base (Fig. 3) and deployed July 18 and 19, 2002. The modules were placed offshore Broward County at four sites, eight modules per site. One site was on a field of coral rubble with abundant H. boergesenii. A second nearby site on a sand field was selected as control, and cleaned of incidental algae coated rubble for a 10 m radius. The third site was on a rubble field adjacent to hard bottom. It also had abundant H. boergesenii, although on this site the algae appeared to be predominately restricted to the underside of rubble pieces. Site four, the control for #3, was located on the hardbottom with abundant hard corals, but which lacked H. boergesenii or abundant rubble. Our hypothesis is: if H. boergesenii provides a coral attractant, more hard coral should recruit to plates surrounded by the algae than in control areas without the presence of the algae. The settlement plates are examined periodically for recruitment.
Figure 3. Example of settlement module.
RESULTS
Coral Transplants
After nine months, there was a highly significant difference
(p<0.01, G-test) between the two species of transplants in growth/mortality;
100% of the M. cavernosa (Fig. 4, 5)
and 71% of the M. meandrites
transplants maintained their original tissue surface area or showed evidence of
an increase in surface area. The
remaining 29% of the M. meandrites
transplants had shown varying degrees of partial tissue mortality.
Figure 4. Transplant 4,
March 2001.
Figure 6.
Transplant 4 on March 2003.
After nine months, the donor colonies have experienced 100% colony survival. Although the core hole sites had not regenerated tissue over the concrete plugs, there had been little tissue die back from the plug sites, and a little growth (about 1%) in some cases. These data were presented at the International Society for Reef Studies in September (Appendix).
After 23 months, 100% of the M. cavernosa and 27.5% of the M. meandrites transplants maintained their original tissue surface area or showed evidence of an increase in surface area (Fig. 6). The remaining 72.5% of the M. meandrites transplants have shown varying degrees of partial tissue mortality (Fig. 7, 8, 9); 35% have died back completely (Fig. 10) and the mortality remains ongoing (Fig.11, 12). The donor colonies continued to experience 100% colony survival. Although there has been some measurable growth (about 4%) onto some plugs, none of the core hole sites have regenerated tissue over an entire concrete plug. However, there has been little tissue die back from the plug sites and so complete regeneration remains probable.
Figure 9.
Transplant 57, June 2003. Figure 8.
Transplant 57, June 2002. Figure 7.
Transplant 57, July 2001.
Figure 10. Example of dead M. meandrites one year
post transplant.
Biofilm
The biofilm study was completed in 2002. The control discs and those incorporating the calcium carbonate did not differ in the settlement rate of bacteria or diatoms. However, the discs with iron filings had a significantly slower settling rate than both the calcium carbonate and control discs (see Appendix for full report and complete results).
Fish Assemblages
As hypothesized there are different fish assemblages associated with the differing fill. For total abundance of fish the empty reef balls did not differ from those with mixed fill however both these treatments were significantly less than either small or large fill (p<0.05, ANOVA, SNK) which did not differ from each other (p>0.05, SNK). With species richness, the empty reef balls had fewer species than those with small fill which, in turn, had fewer than either mixed or large fill treatments (p<0.05, ANOVA, SNK) which did not differ from each other (p>0.05, SNK) (see Appendix).
Settlement Plates
Several corals have recruited to and grown on the Reef Ball attached settlement plates sufficient to allow ready recognition as scleractinian corals (Fig. 13). However, additional growth is required for more specific identification and additional recruitment is required to provide adequate numbers for rigorous statistical evaluation among settlement treatments. In the coming year, we intend to photograph and analyze growth with the same methodology used with the transplanted corals.
Red Algae as Coral Attractant Study
Photos were taken of the settlement plates six months after placement followed by a cursory macroscopic reexamination after one year. No noticeable coral recruits were recorded.
DISCUSSION
The similarity of the microbial fouling of concrete and calcium carbonate coated biofilm discs is interesting. Concrete leaching affecting the results can still not be entirely discounted, as the thin layer of calcium carbonate sand may not have been sufficient to reduce any leachate from the biofilm disc. The significant decrease in the rate of fouling of the iron-coated discs is unexpected; possibly the filings were oxidizing and sloughing off too rapidly for the biofilm to be maintained. Until additional results provide a clear indication of coral settlement preferences, or lack thereof, the results of the biofilm study are difficult to evaluate relative to their potential role in coral recruitment.
The
difference in fish assemblages associated with the differing Reef Ball fill
treatments was anticipated. An understanding of the potential interaction of
these differing assemblages with coral recruitment and mortality awaits the
photographic analysis of the settlement plates. Likewise, the study on the
potential of H. boergesenii to
attract coral to restoration structure has only been underway for a year and
results of this study also await future photographic analysis of settlement
plates. For both the Reef Ball and H.
boergesenii studies there has been
insufficient coral recruitment to date to allow for rigorous analysis. For this
reason, we have extended the study duration for another 12 months. A final
study report will be provided to DPEP July 2004.
However, the data on coral
transplant does already provide some definitive results on species-specific
mortality. The cause(s) of the
mortality difference of the transplants is not clear. M.
meandrites donor corals were
apparently as resistant as M.
cavernosa to the stress of coring.
In addition, when entire colonies of M.
meandrites are transplanted either locally (Vernacchio
and Gilliam, unpublished data) or elsewhere (geology.uprm.edu/Morelock/GEOLOCN_/myzfinalRPT.htm), there is a low rate of mortality. Presumably the difference is due to
differential responses to some other aspect of the coring methodology or
perhaps a species-specific requirement for minimum transplant size. It has been
hypothesized (Kevin Helmle, NSUOC, personal communication) that the mortality
difference between the species may be due to differences in internal structure.
M. cavernosa colonies consist of discrete (plocoid)
monostomodaeal polyps. In contrast M. meandrites colonies are highly integrated (meandroid) and polystomodaeal. Thus, M. cavernosa may simply lose individual polyps to a gross injury, such as coring,
whereas a much larger portion of the M.
meandrites colony may be affected
and a small portion of the colony, such as a core, may not be able to repair
itself. If this is the case, similar differences in transplant mortality might
extend to other monostomodaeal (e.g., M. annularis complex) and
polystomodaeal (e.g. Diploria spp.) species. Obviously, more research is
needed for a causal determination. Nonetheless, the dramatic difference
in survival and growth between M.
cavernosa and M. meandrites transplants clearly
indicates that species selection and potential species-specific responses to
transplant methodology (e.g. coring) must be critical considerations in future
coral reef restoration efforts.