Tracking Coral Larvae to Understand Hawai'i Reef Health

Scientists can predict almost to the hour when the reef-building "rice coral" off Oahu will spawn, but no one knows where the resulting floating coral larvae go.

From June 11-16, 2010, the U.S. Geological Survey, the University of Hawai'i at Mānoa's Kewalo Marine Laboratory, and Malama Maunalua will use satellite-tracked drifters to track the coral larvae's dispersal along O'ahu's south shore in an effort to better understand why certain reefs in Maunalua Bay are doing well and others are doing poorly.

The next coral spawning event will begin after the next new moon, which is June 12. The scientists will use underwater instruments to monitor tides, waves, currents, temperature, salinity, chlorophyll, and water clarity throughout the bay. They will release satellite-tracked drifters to float along with the buoyant coral eggs and larvae and monitor the drifters' positions all night to determine if they are being transported into, retained in, or dispersed out of Maunalua Bay.

During the experiment, boaters and swimmers should keep an eye out for, and avoid the small (8-inch diameter) orange drifters and some small yellow floats marking instrument packages, all with "USGS" markings.

Maunalua Bay has been degraded by polluted runoff and sediment, invasive algae, and unsustainable harvesting. Reduced water and bottom quality tied to watershed discharges and invasive algae affect not only the corals in the bay, but the ability of larvae from elsewhere to replenish depleted populations. Community-based efforts to remove invasive algae and reduce runoff and sedimentation will ultimately lead to improved coral and fish resources. Recovery of the Bay also depends in part on the reproductive health of the local and adjacent coral reefs as sources of coral seed.

Because they are living organisms, corals are born and die. If new corals are not produced and able to settle, replacing those that die from both natural and human-induced causes, the reefs will eventually disappear, along with the other associated marine resources. Once scientists understand the circulation, larval dispersal patterns, and "connectivity" between reefs, managers can identify where recovery efforts should be focused.

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Hawaii at Manoa.

Spectacular Deep-water Coral Province Discovered Off Ireland's West Coast

NUI Galway researchers, during a recent deep-water expedition, have confirmed the existence of a major new coral reef province on the southern end of the Porcupine Bank off the west coast of Ireland. The province covers an area of some 200 sq. km and contains in the order of 40 coral reef covered carbonate mounds. These underwater hills rise as high as 100m above the seafloor.

The deep-water research expedition took place earlier this month aboard the Marine Institute research vessel, the RV Celtic Explorer. The research used the new national Remotely Operated Vehicle (ROV) Holland I to survey the seafloor and capture unique video footage. The expedition, led by Dr Anthony Grehan, was a collaboration between NUI Galway and the Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER) and involved researchers and students from both institutions.
Dr Anthony Grehan, NUI Galway, said: “These are by far the most pristine, thriving and hence spectacular examples of cold-water coral reefs that I’ve encountered in almost ten years of study in Irish waters. There is also evidence of recent recruitment of corals and many other reef animals in the area suggesting this area is an important source of larvae supply to other areas further along the Porcupine Bank”. Dr Grehan suggested that given the rugged terrain, its unsuitability for trawling and its well defined boundaries, that the area would be an excellent additional candidate to the four existing off-shore coral Special Areas of Conservation (SAC). He said that NUI Galway’s Department of Earth and Ocean Sciences would in due course provide a copy of all video footage to the National Parks and Wildlife Service to facilitate them in their work of further SAC designations to comply with the European Union's Habitat Directive.
The expedition began in French waters with a series of ROV dives in previously unexplored canyons in the Bay of Biscay which confirmed the presence of coral and geogenic reefs that will be notified to the new French Marine Protected Area Agency. Dr Brigitte Guillaumont from the newly established agency, said: “The video and images obtained from the high definition video camera of the Irish ROV are very impressive and will greatly assist us in our work of designating areas for the protection of corals”.
Moving into Irish waters, the use of high resolution bathymetry charts, provided by the Irish National Seabed Survey, a collaboration between the Geological Survey of Ireland and the Marine Institute, enabled the identification of new areas likely to support coral reefs. The ROV was then used to dive on one of these areas, the Archipelagos Mounds (or Arc Mounds), to reveal a seascape of spectacular coral reefs. Anna Rensdorf, a Griffith Geoscience PhD student in the Department of Earth and Ocean Sciences, NUI Galway, who had previously worked on tropical corals, said: “I can’t believe that coral reefs like these can be found in the cold waters of Ireland. On many of the mounds surveyed, living coral thickets stood up to 2m high where ordinarily they are less than half a metre in height”.
The NUI Galway study is part of a larger pan-European project funded by the European Commission’s 7th research Framework Programme, called ‘CoralFISH’ that is studying in detail the interactions between corals, fish and fisheries. Dr Grehan, coordinator of the European study, said: “At the recent International Council for the Exploration of the Sea (ICES) deep-sea symposium delegates expressed increasing concern about the level of bottom fishing related damage sustained by vulnerable marine ecosystems (VMEs) in the High Seas (i.e. areas beyond national jurisdiction). Because cold-water corals remain the best example of VMEs, much research is focused on them. One of the key areas in the management of fisheries now appears to be improving our understanding of how fish use habitat. We need to understand what effect damage or removal of that habitat will have on fish stocks and communicating that knowledge to fishermen”.
Dr Grehan noted that vulnerable marine ecosystems such as coral reefs represent one of the last untapped reservoirs of potentially useful bio-compounds that might support the development of new anti-viral or anti-bacterial pharmaceuticals. Currently, there is a major biodiscovery programme underway at NUI Galway funded through the Marine Institute under Sea Change – A Marine Knowledge, Research and Innovation Strategy for Ireland 2007-2013.
Adapted from materials provided by Marine Institute - Foras na Mara, via AlphaGalileo.

Deep sea corals may be oldest living marine organism

Deep-sea corals from about 400 meters off the coast of the Hawaiian Islands are much older than once believed and some may be the oldest living marine organisms known to man.Researchers from Lawrence Livermore, Stanford University and the University of California at Santa Cruz have determined that two groups of Hawaiian deep-sea corals are far older than previously recorded.Using the Lab's Center for Accelerator Mass Spectrometry, LLNL researchers Tom Guilderson and Stewart Fallon used radiocarbon dating to determine the ages of Geradia sp., or gold coral, and specimens of the deep-water black coral, Leiopathes sp. The longest lived in both species was 2,740 years and 4,270 years, respectively. At more than 4,000 years old, the deep-water black coral is the oldest living skeletal-accreting marine organism known."And to the best of our knowledge, the oldest colonial organism yet found," Guilderson said. "Based on the carbon 14, the living polyps are only a few years old, or at least their carbon is, but they have been continuously replaced for centuries to millennia while accreting their underlying skeleton."The research appears in the March 23 early online edition of the Proceedings of the National Academy of Sciences.Using a manned deep-sea research submersible, the team used samples that were individually collected from the Makapuu and Lanikai deep-sea coral beds off the coast of Oahu, Keahole Point deep-sea coral bed off the coast of the Big Island and Cross Seamount about 100 miles south of Oahu.Carbon dating uses radiocarbon (carbon 14) to date the age of an object. Radiocarbon is the most widely used geochronological tool in the earth sciences for the late Quaternary (the last 50,000 years).Earlier radiocarbon studies showed that individual gold coral colonies from the Atlantic and Pacific oceans have life spans of 1,800 to 2,740 years, but the results remain contentious with some biologists. In particular, some have questioned whether the corals feed on re-suspended sediment (which could be old) and not on recently photosynthesized carbon that falls through the water column, or that they grew faster and then stopped growing when they reached a certain size.To answer these questions, the group analyzed not only polyps (the living animals that make up corals) but a branch of one specimen.The living animals had the same carbon 14 concentration as the overlying surface water. This shows that the carbon in the polyps was recently photosynthesized in the surface prior to being "eaten" by the polyps. The skeleton's carbon 14 concentration mimicked that of the overlying surface water's 'post-bomb' time series: the time since the late 1950s when the testing of nuclear weapons augmented the natural abundance of carbon 14 in the atmosphere.The radial growth rate during the last 50 years is similar to the long-term growth rate of the 300-year branch. The radial growth rate also is consistent with that derived from larger fossil samples. The radial growth rate is similar within a rather small range of tens of microns per year for all specimens analyzed.In the recent research, the Geradia coral was assumed to be much younger when amino acid and growth band methods were used. With radiocarbon dating, the average life span of the analyzed specimens is 970 years and ranges from about 300 years for a small branch (with a radius of 11 millimeters) to about 2,700 years (with a radius of 38 mm)."These ages indicate a longevity that far exceeds previous estimates," Guilderson said. "Many of the Geradia samples that we have analyzed are branches, not the largest portions of the colony and so the ages may not indicate how old the entire individual is."Hawaiian deep sea corals face direct threats from harvesting for jewelry and from commercial fisheries that trawl the ocean bottoms. In addition, the close relationship between deep sea corals (and the mid-water ecosystems) and ocean's surface means that they can be affected by natural and manmade changes in surface ocean conditions including ocean acidification, warming and altered stratification.The antiquity of the coral is an additional call for action, Guilderson said."The extremely long life spans reinforce the need for further protection of deep-sea habitat" he said. "The research has already had an impact for activities in Hawaiian waters where a harvesting and fishing moratorium has been enacted to protect certain areas. There are similar habitats in international waters and it is hoped that the results will provide the scientific basis for agreements under the Law of the Sea, and United Nations Environment Programme."Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration.Lawrence Livermore National Laboratory

Seamounts May Serve As Refuges For Deep-sea Animals That Struggle To Survive Elsewhere

Over the last two decades, marine biologists have discovered lush forests of deep-sea corals and sponges growing on seamounts (underwater mountains) offshore of the California coast. It has generally been assumed that many of these animals live only on seamounts, and are found nowhere else.

However, two new research papers show that most seamount animals can also be found in other deep-sea areas. Seamounts, however, do support particularly large, dense clusters of these animals. These findings may help coastal managers protect seamounts from damage by human activities.
Tens of thousands of seamounts dot the world's ocean basins. Although some shallower seamounts have been used as fishing grounds, few seamounts have been studied in detail. Davidson Seamount, about 120 kilometers (75 miles) offshore of the Big Sur coast, is an exception. Since 2000, researchers have spent over 200 hours exploring its slopes and peaks using the remotely operated vehicle (ROV) Tiburon.
Two of the expeditions to Davidson Seamount were led by Andrew DeVogelaere of the Monterey Bay National Marine Sanctuary and were funded by the National Oceanic and Atmospheric Administration's Office of Exploration. Other expeditions were funded by the David and Lucile Packard Foundation (through MBARI) and were led by MBARI biologist James Barry, who studies seafloor animals, and by geologist David Clague, who studies undersea volcanoes.
Following each expedition to Davidson Seamount, marine biologists at MBARI studied high-resolution video taken by the ROV and identified every animal they could see. Over 60,000 of these observations were entered in MBARI's video annotation and reference system (VARS). Craig McClain and Lonny Lundsten, the lead authors of the two recent papers, used the VARS database to find out which animals were unique to Davidson Seamount and which had been seen elsewhere.
Altogether, 168 different species of animals were observed on Davidson Seamount. McClain's search of the VARS database showed that 88% of these animals had also been seen or reported in other deep seafloor areas, such as the walls of Monterey Canyon. Three quarters of the species on Davidson were not even unique to the California coast, and had been seen in seafloor areas over 1000 kilometers (620 miles) away, including the Hawaiian Islands, the Sea of Japan, and Antarctica.
Only about seven percent of the species at Davidson Seamount had never been seen anywhere else. Of these 12 apparently "endemic" species, most were new to science. Thus, their full ranges are still unknown.
Although few animals are "endemic" to Davidson Seamount, the research demonstrated that this seamount does support distinctive groups of animals, which are dominated by extensive "forests" of large, "old-growth" corals and sponges. These same species of corals and sponges also grow on the walls of Monterey Canyon, but usually as smaller, scattered individuals. Conversely, sea cucumbers are common on the walls of Monterey Canyon, but are rare at Davidson Seamount. Thus, animals that are common on Davidson Seamount are uncommon in other seafloor areas, and vice versa.
The researchers speculate that Davidson Seamount is a good habitat for deep-sea corals and sponges because it has favorable bottom materials (bare lava rock), a steady food supply (drifting particles of the right size and type), and may be less disturbed by strong bottom currents than other seafloor areas. Craig McClain, one of the lead authors, explains, "The large groves of corals and sponges are unique to seamounts. The crests of seamounts are particularly good because they provide flat rocky surfaces that don't accumulate much sediment. This is partly due to the fact that seamounts are so far offshore."
In contrast, McClain points out, "When you look at the seafloor in Monterey Canyon, it's mucky. That makes it tough for filter feeders, especially sponges. Any flat surface in the canyon collects mud. This makes it tough for corals to settle anywhere except on near-vertical surfaces. Just staying attached to these surfaces can be a challenge in itself."
McClain and Lundsten's research also suggests that seamounts such as Davidson Seamount may be ecologically important as breeding grounds for animals that are rare in other habitats. As McClain writes in his paper, "seamounts are likely to be sources of larvae that maintain populations of certain species in sub-optimal, non-seamount sinks." He explains, "Sources are places where certain species do really well—they're self sustaining populations. Sinks are areas where these species can live, but do very poorly. Populations in sink areas will die out if they're not continuously replenished by new animals from source areas." The researchers suggest that future DNA studies of seamount animals would help scientists find out if seamounts are indeed sources of larvae for other seafloor areas.
Lundsten's paper emphasizes the fact that not all seamounts are alike. For example, Rodriguez Seamount, a smaller seamount offshore of Point Conception, once extended above sea level. Thus, Rodriguez Seamount has a flat, sediment-covered crest that is partially covered with ancient beach sands. These sands have been colonized by a very different set of animals from those at Davidson Seamount. In fact, sea cucumbers are the most abundant animals on Rodriguez Seamount.
In 2008, Davidson Seamount was added to the Monterey Bay National Marine Sanctuary. Findings from McClain's and Lundsten's papers will provide critical information for managing Davidson Seamount, and could be useful in other sea-life protection efforts around the world. Prior to this study, seamounts were considered isolated biological "islands," which might require management to protect certain unique species. This study, on the other hand, suggests that seamounts should be managed as entire communities, whose dense populations of animals release larvae that help colonize other, less optimum environments. Either way, the authors point out, seamounts are well worthy of our protection.
Adapted from materials provided by Monterey Bay Aquarium Research Institute.