|By Reef Check EcoDiver Course Director Stephan Moldzio
During our Reef Check (RC) surveys in February 2012 at Marsa Shagra, Red Sea, Egypt, we observed some strange circular blotches on a fire coral Millepora dichotoma. We sent these pictures to RC and made an inquiry to several experts with no conclusive outcome.
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Initially we took the following explanations into consideration:
- Feeding scars by Coralliophila snails
- Feeding scars by juvenile Crown of Thorns seastars (COTS)
- Some kind of coral disease
- Anomaly of Millepora
Coralliophila is frequently observed on Porites corals, where it produces slight feeding scars, whereas the tissue remains mainly alive and intact. But Coralliophila feeds exclusively on Porites and is most unlikely to feed on any other corals, including Millepora. Another point against Coralliophila is that they were obviously absent on Millepora, whereas they are usually observed in close vicinity due to their small feeding territory.
Juvenile COTS are ruled out, because COTS tend to create paths instead of single blotches. We actually have observed a young COTS feeding scar on a Favia coral during our surveys; the tissue was completely removed – in contrast to those circular blotches on Millepora that appeared a bit bleached but not grazed down to the bare skeleton. Later, we found out from Prof. Rupert Ormond that COTS actively avoid Millepora because they are stung by it!
Some kind of coral disease might also have been the cause, but an infection with ciliates or bacteria tends to spread over the whole colony and does not form such equal sized and sharp edged blotches.
At that time, we preferred the explanation of an anomaly of Millepora. I observed in my aquarium that Millepora often forms "tissue bubbles" at branches as well as "bleached" small areas; but not such perfectly round patches.
So we uploaded the pictures to RC Europe´s homepage and posted an inquiry through the “NOAA Coral List Server,” from which we received more than 20 emails with possible explanations. These ranged from feeding scars by COTS, Coralliophila, Drupella, parrotfish, damselfish, butterflyfish, filefish, blennies (Exallias brevis), corallivorous flatworms, White Pox disease, a secondary infection of a feeding scar and a special form of bleaching.
Zvuloni et al. (2011) described exactly the same phenomenon in Millepora as “Multifocal Bleaching”, but they didn´t determine the reason for these patches. They suggested a form of bleaching, a “new syndrome in Millepora,” possibly caused by a microbial infection.
Finally, Dr. Bruce Carlson in Hawaii solved this mystery by uploading a video showing the feeding behaviour of the leopard blenny, Exallias brevis, and describing the exact mechanism of how it forms these remarkable feeding scars: Exallias brevis is an obligate corallivore that scrapes off the tissue with its upper jaw while anchoring the mouth with its lower jaw, producing sharp edged, circular feeding scars! Indeed, all of those blotches, even those published in Zvuloni´s paper, showed a faint white line under the circular feeding bite! “That line represents the lower jaw that anchors the mouth while the upper jaw sweeps over the coral and removes the tissue,” Carlson stated. He also mentioned that on the picture “some of the older scars have regenerated a bit and a newer scar overlaps the older scar. That can only be produced by feeding, i.e., it rules out bleaching or disease.” Carlson is submitting a paper to Marine Ecology Progress Series with a complete description of the feeding behavior of Exalllias brevis.
Carlson (1992) found out that only the superficial coenosarc tissue was removed while the polyps remained mostly intact within calyces and that these marks regenerated within 50 days. He observed E. brevis feeding exclusively on living corals, at rates of 13.9 and 28.4 bites per hour for males and females, respectively. He sized the circular feeding bites on Porites lobata to 2.04 ± 0.42 cm².
Dr. Carlson has observed E. brevis feeding on Millepora as well at Enewetak Atoll in the Pacific. Dr. Jürgen Herler stated that E. brevis removes coral tissue, at least for breeding, and he sent a photo with the fish and its egg patches on a Millepora in the Red Sea. Finally, Christian von Mach confirmed that he observed E. brevis feeding on Millepora in the Gulf of Aqaba/northern Red Sea.
In the following days we had a lively discussion upon this matter….
Why have these circular patches not been reported until now?
Why has it been such a problem (for many experts) to determine these patches as Exallias brevis feeding scars?
We have conducted RC surveys in that area for four years, but this was the first year we observed these circular patches. If Exallias brevis is not very abundant, divers would have seen just a minor density of feeding scars. Thus, this phenomenon may not have been obvious, being perceived only by a watchful observer, who knows about coral diseases, coral bleaching and feeding scars. Additionally, E. brevis hides deep within Millepora thickets, so any observer would have to come really close and rest for a while to watch E. brevis feeding. Such an observer would have to be quite persistent to get an answer about whatever is responsible for these blotches. So we think that this phenomenon has simply not been recognized and/or been acknowledged to be published so far.
Furthermore, most divers and snorkelers may avoid coming too close to Millepora, because it´s also called “fire coral”. Also, the preferred habitat of Millepora and E. brevis is around the reef crest at shallow depth, whereas most divers are going to 10-30m depth.
E. brevis may show some ecological differences within its range from the Red Sea, Madagascar and India, to Australia and Hawaii. In the Egyptian Red Sea we´ve observed E. brevis always within the Millepora thickets at shallow depth around the reef crest. We didn´t observe it on any other corals, e.g. Porites, where it was mainly observed by Dr. Carlson in Hawaii.
It´s quite possible that in some cases, disease may in fact simply be some kind of feeding scar.
Stories like this one happen when thousands of Reef Checkers put their eyes on the reef, with a focus on all kinds of human impacts, coral damage, recently killed corals, bleaching, coral diseases, and COTS feeding scars.
But one part of this mystery remains: similar scars on Millepora complanata have been observed by scientists from Bermuda, the Florida Keys, the Mexican Caribbean and Pernambuco, Brazil. So far, no one has identified the fish that creates these spots. Exallias brevis does not occur in the Caribbean but it has close relatives there. Charles Delbeek mentioned that Ophioblennius atlanticus has a very similar mouth structure to E. brevis and lives in close proximity to stands of Caribbean fire coral.
There are many secrets on the reef waiting to be uncovered and we are still searching for a corallivore equivalent of E. brevis in the Caribbean.
|By Stephan Moldzio, Reef Check Team Scientist & EcoDiver Trainer
Since we started our Reef Monitoring Programme with Red Sea Diving Safari (RSDS) in 2009, we have run four EcoDiver courses with 19 participants from ten different countries. Every participant has successfully been certified as a Reef Check EcoDiver. With this dynamic team we have conducted 20 Reef Check surveys at the ten most important RSDS dive sites. Each location has been surveyed twice along two depth contours (3.5 m & 8.5 m depth), so all in all we have contributed 40 data sets that have been included in the international database at Reef Check HQ, which currently includes 8,513 surveys in 99 countries & territories.
As in previous years, participants appreciated the opportunity to learn and apply the Reef Check method to monitor the abundance of specific reef organisms, and human impacts that reflect the condition of the coral reef ecosystem. A particular motivation for participating in Reef Check is that volunteers are contributing to real science by collecting valuable data about the health status of coral reefs. The data is an important tool for local reef managers and decision makers, as well as scientific publications such as the “Status of Coral Reefs in the World” report. This year, everyone was very keen to start with the field work, so our group conducted five surveys at Marsa Egla, Elphinstone, Marsa Gabel El Rosas, and two sites at Wadi Lahami.
Within our 40 surveys, we found a total coral coverage (hard and soft corals) of 50.8% ± 4.3% compared with a value of 50.5% ± 3.1% in 2009/2010. At 3.5m depth we found coral cover of 52.2% ± 3.7% and at 8.5m depth 49.7% ± 4.8%. For all non-living substrate categories - rock, rubble, sand, silt, and recently killed coral - we recorded an average percentage cover of 47.6% ± 4.6% for all surveys. In 2009 and 2010 we found 47.7% ± 3.1% non-living cover.
The 2012 fish counts remained relative to those conducted in 2009 and 2010. Again, the most abundant indicator group were butterflyfish with 6.0 ± 1.5 individuals/500 m³, followed by parrotfish (2.5 ± 0.9 Ind./500 m³). The average abundance of groupers was 1.3 ± 0.4 Ind./500 m³, a slightly increased value with respect to 2009 and 2010 (0.7 ± 0.3 Ind./500 m³).
With regard to coral cover, our Reef Check surveys indicate that reefs at the ten surveyed sites remain generally healthy. Sewage and other pollution, as well as sedimentation from soil erosion do not seem to be a problem. We did not observe any coral diseases, excessive nutrient indicator algae, or sponges at the surveyed sites. Coral recruitment was good, especially at places with anchor damage where new coral colonies were beginning to grow and build up the next generation.
Perhaps the most striking finding was that the results were quite similar to the previous years’ surveys, possibly due to the application of permanent transects.
To read the full Marsa Shagra Annual Report, please click here.
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By Reef Check Italia’s Gianfranco Rossi
Divers of Subtridente Pesaro, scientists of Reef Check Italia Onlus and public institutions came together in June for the protection and conservation of biodiversity of the northern Adriatic Coastal Marine Environment.
The northern Adriatic Sea gives the Mediterranean basin one of the highest rates of biodiversity on the entire planet. Promoting this fact and involving the public is crucial so that the legacy of this sea will be conserved and protected for our own well-being, and so that future generations can learn that it is a duty of every institution from the highest level to single citizens to keep this ecosystem healthy.
For these reasons Subtridente Pesaro, Province of Pesaro-Urbino, Natural Park of S. Bartolo and Reef Check Italia Onlus organized an event on June 8th & 9th, 2012, included in the activities promoted by the United Nations, to celebrate the International Day for Biological Diversity. During these two days, scientific reports and monitoring activities took place, involving a great number of citizens.
Prof. Roberto Danovaro, Director of the Department of Science of Life and Environment (DiSVA) at the Polytechnic University of Marche (UNIVPM), has summarized the results of more than ten years of research concerning the Census of Marine Life project. These data show that the number of species present in the Mediterranean basin is about 17,000, but this is surely an incomplete number. The diversity of microbial species is certainly underestimated and the deepest areas of the sea are still unknown.
As a whole, unfortunately, we are witnessing a decrease in biodiversity throughout the area. Nearly all major species belonging to the macrofauna, and best known by people in general, are in progressive decline. On the contrary the number of alien species, coming in particular from the eastern part of the basin, is constantly increasing.
These species are rapidly spreading westward because of the warming of Mediterranean waters and constitute a real threat to the biodiversity throughout the area. Throughout the Mediterranean there are clear and visible signs of overfishing, pollution, loss of habitat and biodiversity, primarily coming from impacts of anthropic origin. Along with climate change, these are the main threats against these unique ecosystems.
Following these assumptions dott. Carlo Cerrano, researcher at DISVA, and president of Reef Check Italia Onlus, has focused his attention on what constitutes a biodiversity "hot spot" inside the main "hot spot" of the entire Mediterranean basin. He has discovered that the northern Adriatic Sea, namely that portion of the northern basin enclosed north of the line joining the cities of Ancona and Zadar, fits within the criteria.
The current knowledge of the biodiversity of the whole Mediterranean region dates back to the distant past, to Greek and Roman times with Aristotle and Pliny. It continues through the findings of Linnaeus to the recent discoveries of J. Jacques Cousteau. Ecological research and the discovery of species in the Adriatic region come from detailed studies by various authors starting from the famous manual of R. Riedl. Several publications in recent years have tried to focus the interest of researchers and people in general on the northern Adriatic Sea. This change has produced very important scientific results because only through a deeper understanding of the biodiversity and dynamics that characterize this particular kind of habitat will it be possible to start the most useful initiatives to increase the value of an environment as precious as it is misunderstood and underestimated.
The day after this event was the start of the monitoring activities of the sea bottom and the beach in front of the natural park of San Bartolo. With the help of many volunteer scuba divers of Subtridente Pesaro and students at the high school Liceo Scientifico G. Marconi of Pesaro, began the first monitoring activity using the Marine Coastal Environment protocol of Reef Check Italia Onlus.
This activity has been very helpful in designing a map of this area that will be a useful baseline for future monitoring. Increased and regular monitoring in subsequent years will help us to collect a greater number of data. Free access of data on RCI’s database for agencies will be a useful tool for conserving and protecting the resources of this area and ultimately of the entire Mediterranean basin.
For more information, visit the Reef Check Italia website.
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With September 8th right around the corner, Reef Check is organizing its annual "Save the Reefs, Save the Oceans" gala at the Jonathan Beach Club in Santa Monica.
The evening will recognize the contributions of our “Heroes of the Reef” each having demonstrated an exemplary commitment to ocean conservation.
Our honorees include California Assemblymember Paul Fong, who will receive the Reef Stewardship Award for his commitment to the conservation of our seas, demonstrated by his leadership in the authoring and successful passage of the bill banning the sale or possession of shark fins in California, as well as his current efforts to raise awareness and protect the Leatherback Sea Turtle.
Receiving the Poseidon Award are Commissioner Richard B. Rogers from the California Fish & Game Commission, William W. Anderson and Gregory F. Schem from the MLPA Blue Ribbon Task Force, and Don Benninghoven, MLPA Blue Ribbon Task Force member and former California Fish & Game Commissioner. They are being recognized for their leadership and public service in the creation of a statewide network of marine protected areas in California through the Marine Life Protection Act (MLPA).
Our Gala will also include silent and live auctions featuring fabulous vacations, fun activities, and an assortment of gift certificates. Don’t miss your opportunity to be part of a wonderful night, tickets can be purchased at http://www.reefcheck.org/events/gala2012/
Sponsorship and auction donation opportunities are also available.
For additional information please call Reef Check at 310.230.2371 or email email@example.com