¹ Department of Biology, Ochanomizu University Otsuka, Bunkyo-ku, Tokyo JAPAN

mhatta@cc.ocha.ac.jp

　

²Akajima Marine Science Laboratory Zamami-son, Okinawa, JAPAN

　

Coral reefs are the bases of marine ecosystems and environments in tropical and sub-tropical regions. Despite their importance, coral reefs all over the world are declining at an alarming pace as a consequence of direct and indirect human activities even though preservation and management measures have been taken. On the other hand, methodologies for restoration of degraded marine ecosystems, particularly coral reefs, are still in their preliminary stages.

　

In Indo-Pacific reefs, the coral genus Acropora is especially important since it consists of major components of the reefs, and coral communities are maintained in a large part by recruitment of their larvae. Huge numbers of larvae are produced by sexual reproduction, but most of the larvae are lost prior to metamorphosis and settlement in nature. If the larvae are collected and grown to colonies under controlled conditions, they could be used as donors for transplantation without damaging existing coral communities. The problem had been lack of ways to control metamorphosis and settlement of Acropora.

　

We found that one of hydra neuropeptides can induce metamorphosis and settlement of Acropora larvae at 100% efficiency. The hydra peptide is thought to mimic the endogenous peptide hormone(s) and trigger metamorphosis. The peptide is successfully used to produce primary polyps on proper substrates from collected larvae of Acropora. The primary polyps could be used for transplantation aiming reconstruction of denuded reefs. We believe that these findings will first provide a breakthrough to turn "coral seedlings production" into reality.

　

　

¹Department of Mechanical and Environmental Informatics Tokyo Institute of Technology Tokyo, JAPAN

nadaoka@mei.titech.ac.jp

　

²Tokyo University of Science, Chiba, JAPAN

³Okinawa Subtropical Environment Remote-Sensing Center Communications Research Center Okinawa, JAPAN

⁴Okinawa Prefectural Fisheries Experiment Station, Okinawa, JAPAN

⁵Research Institute for Subtropics, Okinawa, JAPAN

⁶Aakajima Marine Science Laboratory, Okinawa. JAPAN

⁷Alec Electronics Co., LTD., Tokyo, JAPAN

　

For examining the long-distance transport of coral larvae (planulae), which may be important for the recruitment in the restoration process of the heavily damaged coral reefs due to mass bleaching, we have made field measurements with slick tracking using an air craft, newly developed GPS-installed drifters, an HF-ocean radar system, a plankton netting, and others to reveal the larval transport process from the Kerama Islands to the west coast of Okinawa Island, Ryukyu Islands. Japan, and have examined larval movement and settlement rate in the laboratory studies.

　

In the field measurements performed in 1999 and 2000, we found that the current characteristics in the shelf region including the Kerama Islands and those in the area beyond the shelf edge is quite different; i.e., in the former the currents are dominated by tidal motion and in the latter appreciable effects of the Kuroshio-related warm water may appear in unsteady manner. In 2001, we made a field survey by focusing the direct larval tracking using the drifters, and found that surface particle (planulae) dispersed from the Kerama Islands to the west coast of Okinawa Island in 3.5 to 4 days after spawning. Planulae were observed around the drifters reached near Okinawa Island, indicating that the drifters tracked well the larval transport trajectories. These periods correspond with the time to show the highest rate of larval crawling on the substratum, suggesting that planulae disperse and recruit from the Kerama Islands to the west coast of Okinawa Island.

　

　

Marine Laboratory, University of Guam Mangilao, GUAM

richmond@uog9.uog.edu

　

Coral reefs throughout the world have been affected by human-induced disturbances. The scale of damage ranges from individual patch reefs impacted by ship groundings to regional events, (e.g., bleaching attributed to global climate change) affecting tens to hundreds of thousands of coral colonies. Synergisms among stressors can exceed the ability of coral colonies and entire reef communities to persist and/or recover. Reductions in coastal water quality can affect coral growth and reduce fecundity of coral colonies. Increased levels of specific pollutants, including freshwater and heavy metals can prevent or disrupt the formation of larvae during mass spawning events. Sedimentation and pollution from pesticides and hydrocarbons can inhibit recruitment of coral planulae larvae requiring specific metamorphic inducers found in crustose coralline algae. Eutrophication from sewer outfalls and fertilizer runoff can lead to increased growth of fleshy algae preventing coral larvae from finding appropriate settlement substrata. If populations of herbivorous fishes are depleted, an alternate stable state can arise. Predictive indicators of sublethal stress are needed to serve as early warning systems allowing responses before outright mortality occurs. History has taught us that reefs can recover from large-scale mortality events, however, recovery depends on restoration of conditions that allow corals and associated organisms to survive, grow, reproduce and recruit. The future of coral reefs relies on effective partnerships among resource managers, researchers, stakeholders, policy makers and educators.

　

　

Palau International Coral Reef Center Koror, PALAU

surculosa@yahoo.com

　

The effect of copper on fertilization and settlement in corals is of environmental concern because there are numerous sources of copper to coral reefs. Fertilization and the settlement process are an important life history events leading to successful recruitnent of new individuals to maintain coral populations. Little is known of the sensitivity of early developmental stages in corals to pollution. Inhibition of fertilization and settlement of gametes from Acropora surculosa was assessed in response to solutions of copper (CuSO₄) using laboratory based bioassay.

　

Spawned gametes were collected and exposed to nominal concentration of copper for 5 hour and for 12 hours. After exposure to the solution, the number of fertilized and developing embryos and unfertilized eggs were counted and recorded to determine percentage fertilization. High fertilization rates of 99% was observed in the control after 5 hour exposure. Copper inhibited fertilization to 90% in 10 ppb and to 90% in 200 ppb. The estimated EC50 for gametes was 38.04 μg/1.

　

Laboratory cultured larvae that were five days old were exposed to the same concentration of copper used in the fertilization bioassay. Larvae were given a substratum (artificial or natural) in two separate bioassays to settle and metamorphose on for 48 hours. In both bioassays, larval settlement was significantly different from the control at copper concentration of 75 ppb and 100 ppb. There was no different on settlement rate with regard to the type of substratum that were used.

　

These data indicate that fertilization success and larval settlement in corals may be sensitive to the presence of contaminants in seawater. Tropical islands surrounded by coral reefs have come under tremendous development pressure that can increase the potential for leaching of contaminants to affect the life cycle of corals. As annual spawning events are predictable, management initiative can be develop to protect coastal waters during these critical periods.

　

　

Australian Institute of Marine Science Queensland, AUSTRALIA

e.wolanski@aims.gov.au

　

Fouha Bay is a 400 m long funnel-shaped, 10 m deep, coral-fringed embayment on the southwest coast of Guam. It drains a small catchment area (5km²) of steeply sloping, highly erodible lateritic soils. River floods are short-lived and the sediment load is very large, with suspended sediment concentration exceeds 1,000 mg 1-1. The resulting river plume is about 1 m thick and pulses in a series of 1-2 hours long events, with outflow velocity peaking at 5 cm s-1. Turbulent entrainment results in an oceanic inflow at depth into the bay. As soon as river flow stops, the plume floats passively and takes five days to be flushed out of Fouha Bay. The suspended fine sediment flocculates in 5 min and aggregates on ambient transparent exopolymer particles to form muddy marine snow flocs. In calm weather, about 75% of the riverine mud settles out of the river plume into the underlying oceanic water where it forms a transient nepheloid layer. This mud ultimately settles and is trapped in Fouha Bay. Under typhoon-driven, 4-m swell waves, the surface plume is at least 7 m thick and bottom entrainment of mud results in suspended sediment concentration exceeding 1,000 mg 1-1 for several days. Observed rates of sedimentation and marine snow deposition are proving to prevent coral larval recruitment and cause mortality in small coral colonies. It is suggested that management of coral reefs adjacent to volcanic islands may not be possible without appropriate land-use management in the surrounding watershed.