Grain Size Distribution and Fate of Transplanted Corals at Kawaihae, Hawaii: Field work of 1996-1997 (NODC Accession 0001141)

Large-scale transplant method Divers first placed 1 m x 1 m squares of chicken wire (5 cm mesh) on the substrate adjacent to the collection site. A float was tied on one end of a 25 m line and a large spring clip tied to the opposite end. The line was clipped onto to one corner of the chicken wire mesh, serving as a visual marker for the divers. This line was used later to haul the corals off the bottom. Divers then moved corals and placed them on the chicken wire. Most corals were loosely attached to the substratum or rested on unconsolidated material and were easily moved. Occasionally, a sledgehammer was used to loosen corals that were too large or firmly attached.When the chicken wire was amply covered with coral, divers secured the four corners with the clip, forming a sling. The divers then returned to the boat and completed the operation with no personnel in the water. When all personnel were safely out of the water, the boat engines were started and the boat maneuvered alongside of the floats. The float was retrieved, and the two or more persons hauled the bags off the bottom.The bags were hoisted close to the surface, and the lines were tied off on cleats. Generally four bags of corals were carried on each boat trip. The boat slowly transported the corals to the transplant sites. Bags were lowered to the bottom, and the floats thrown clear of the boat, after which time the boat was anchored and secured. Divers then entered the water to set up the transplant stations. Corals remained fully immersed in water throughout the operation. All of the corals moved in this operation were massive colonies typical of high water motion environments. These corals can be handled with little or no breakage. Much more care would have been required if we were transplanting delicate species. Establishment of the eight transplant plots: The position of each transplant site was established using sightings on prominent land features. At each experimental site, a 2.5 m x 2.5 m squareof wire mesh was firmly attached to the bottom using stakes cut from steelreinforcing rod and large nails. Corals were then placed and secured to the grid with wire. Four sediment traps were attached to stakes at each site. Photographs and video were taken and used to compile detailed maps of the corals located at each transplant site. These maps were subsequently used by divers to monitor survivorship of corals. A total of 47 bags of coral were moved. Bags are estimated to weigh between 45 and 70 kg buoyant weight. Taking an average of 58 kg, an estimated 2,700 kg buoyant weight was moved. The ratio between buoyant weight and wet weight for Porites compressa, one of the dominant species in the area, was calculated to be 2.76. Thus approximately 7,500 kg (16,000 lbs) wet weight was moved. Monitoring of transplant plots at approximately monthly intervals (depending on weather andsurf conditions) the plots were visually sampled for condition of corals. Depth of sediments at the 35 Ft. and 45 Ft. sites was measured using permanent stakes. Sediment traps were replaced and the contents analyzed. Sediment Sampling Polyvinylchloride plastic (PVC) cylindrical pipes, interior diameter 5.2 cm, were used as sediment traps. The recommended diameter to length ratio of 1:3 (Gardner 1980a, b) was used. Four traps were deployed at each site, with one placed on each corner of the 2.5 x 2.5 m wire grid, with the mouth of the traps held 30 cm above the substrate with plastic stands. Trap contents were collected at roughly monthly intervals by capping the open tops of the traps and bringing the unit to the surface. Sediments were collected on pre-weighed filters and air dried to a constant weight. Bulk samples, characteristic of the benthic substratum, were collected at each site in November 1996. Scoop samples of approximately 50 g were collected from the top 10 cm of the substratum at each site. Sediment Analyses: Grain Size Analysis: Samples were homogenized and wet filtered through a large mesh sieve (2.8 mm) to remove small rocks. The remaining material was wet filtered through sieves representing gravel (>500 um), coarse sands (between 500 and 250 um), fine sands (between 250 and 63 um), and silt (<63 um) (McManus, 1988). Sieved materials were collectedon pre-weighed filters and dried to a constant weight. The proportion of material in each size class was determined. Organic and Carbonate Fraction Samples were dried and homogenized. Sub samples of approximately 10 g were dried at 60 deg C for 8 hours, and then ashed at 500 deg C for 12 hours. Organic fraction is expressed as Losson Ignition (LOI). The samples where then ashed at 1000 deg C for 4 hours to break down the carbonate (Parker, 1983; Craft et al.,1991). Sediment Mobility: Depth of the sediments at the 35 Ft. and 45 Ft. sites were measured monthly using permanent stakes. Two stakes were installed at each site: one close to the existing hard coral substratum and one centrally located within the sand channel.