|The Transect Line – January 2012||Newsletter Archive|
|Reef Check Spotlight: Why Do Hammerheads Have Hammer Heads?|
|By Cara Hodgson
Sharks are one of the increasingly rare organisms seen on coral reefs. They have been eliminated from many reefs due to demand for their fins to make shark fin soup, a Chinese delicacy. In 2011, there were some big “wins” for sharks with shark finning and trading banned in several areas. Because shark sightings are now so rare just about everywhere, Reef Checkers are asked to record any sharks during their dives – even of those observed off of the transects.
One type of shark has always held a fascination as a kind of prehistoric-looking oddity that one might think was dreamed up by a Hollywood horror filmmaker – not a result of millions of years of evolution. This is the hammerhead shark. A related shark is the bonnethead – with a head shaped more like a shovel.
Looking at the wide separation between the hammerhead’s eyes, and the flat surface of the head, one wonders about the evolutionary advantage of this design?
Several hypotheses explaining the evolution of the hammerhead shark’s head – called a “cephalofoil” – have been proposed.
One is Stephen M. Kajiura’s enhanced electrosensory hypothesis. All sharks have special gel-filled pits on their lower jaw and around their “face” that are used to detect electromagnetic radiation, such as the nerve impulses in the muscle of a fish hiding in the sand. A preferred prey item for hammerheads is the stingray – often resting buried under sand. Hammerheads have more electrosensory pores (called Ampullae of Lorenzini) than other sharks because they are spread over the wider cephalofoil of the hammerhead. Kajiura hypothesizes that the wider, flatter head allows hammerheads to have electroreceptor pores more spaced out so that the sharks can search and forage a larger area – sort of like a wide beam flash light.
A second hypothesis is that since the hammerhead’s eyes are positioned at the ends of the cephalofoil, some researchers think that this helps them to see better than other sharks. This could be because of a wider overlap in binocular vision.
The third hypothesis proposed is the ability of the cephalofoil to improve the shark’s movement in the water by providing hydrodynamic lift. Most sharks need to swim continuously to pass water over their gills. The additional lift provided by the cephalofoil may reduce the effort needed for hammerheads to swim. Also, hammerheads have more muscles around their head and vertebral column which results in greater flexibility and greater ability to move their heads. Other sharks do not have musculature to allow them to depress their heads.
This extreme movement is needed for sharks that feed on benthic prey since the shark needs to make a rapid turn away from the ocean floor after attacking its prey. If the turn is not made sharply enough, the shark could end up running into the ocean floor. In addition, since it is dangerous to capture stingrays, hammerheads have developed a way to hold the stingrays down with their cephalofoils until they are traumatized and immobilized, so that they can feed on it without being impaled by the stingray’s tail spines.
The cephalofoil also seems to provide a similar function to the pectoral fin on other sharks since the hammerheads have a much smaller pectoral fin than other species. Because the cephalofoil is larger than a pectoral fin and is further from the center of gravity on the shark, it therefore is better for movement and provides better hydrodynamic lift than a fin centered in the middle of the shark’s body.
Regardless of the ultimate cause or causes of the evolution of the hammerhead shark’s head, the hammerhead has adapted to become an aggressive and efficient predator while remaining one of the most identifiable creatures of the sea.
|Reef Check California Update|
|By Reef Check California Director Dr. Jan Freiwald
The 2012 training schedule is up! Join our ranks as a citizen scientist by participating in one of our trainings. There are seven courses, from Ft Bragg to San Diego, available for new Reef Checkers. If you are interested in surveying with us again this year, there are seven opportunities to be recertified. Spots are limited, so sign up today at http://reefcheck.org/rcca/training_schedule.php
In preparation for the upcoming field season, we have been entering the last of our 2011 data. We are looking forward to getting back into the water soon to build on the success of last year, having completed 13 training courses and 10 recertification courses. We expanded the geographic range of our program and trained 244 Reef Checkers statewide.
We also have organized several trainings, lectures and events for the upcoming weeks. We will have several lectures at the Monterey Bay Aquarium, volunteer parties in Monterey and Long Beach, and Reef Check California will be at the Underwater Parks Day at the Long Beach Aquarium on January 21st. Stay tuned for details on these events at the Reef Check forum.
We wish you a Happy New Year and are looking forward to seeing you all in 2012!
|Marine Parks Show Success in Indonesia|
|By Jenny Willis, Reef Check Indonesia
Recent research supports observations from Reef Check Indonesia that marine reserves increase the diversity and abundance of plants and animals within them.
The Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) has completed a review of more than 200 peer-reviewed recent scientific publications about 150 marine protected areas in 61 countries, and has concluded:
• Biomass, or the mass of animals and plants, increased an average of 446%.
It also found that increases were similar in places of different latitude, in both temperate and tropical reserves.
Reef Check Indonesia Field Officer, Derta Prabuning said the finding of the PISCO research is supported by anecdotal reports given to him by local fishermen.
“Additional to the ecological monitoring we do regularly, the best indication comes from what we hear from the fishermen’s experience. Fishermen are saying there appears to be increasing fish abundance since the Locally Managed Marine Areas (LMMAs) were set up in Bondalem (2008) and Tejakula (2009).”
Derta also said it now appears that more rare ornamental fish can be found in the LMMAs and that there appears to be lots of new coral growing. More research is needed in Indonesia to verify these observations.
You can read the report from PISCO here at http://www.piscoweb.org/publications/outreach-materials/science-of-marine-reserves-0
For more information, contact Reef Check Indonesia at email@example.com
|Coral Bleaching Management in Malaysia|
|By Reef Check Malaysia
Coral reefs are valuable resources, attracting millions of visitors each year to Malaysia. It is estimated that coral reefs in Malaysia are worth some US$600 million annually through direct and indirect revenues from the tourism and fisheries industries and coastal protection.
In the Indo-Pacific, bleaching events have been widely reported since the 1980s. Coral bleaching occurs when corals are stressed by environmental conditions such as unusually high sea temperatures, low salinity, and exposure to toxic chemicals. It is characterized by the loss of microscopic algae called zooxanthellae that live within the tissues of most corals. Zooxanthellae not only provide corals with a food supply, they are also responsible for giving corals their distinctive green and brown coloration.
More recently, Malaysia experienced bleaching events in 1998, 2004 and 2010. Widespread coral bleaching occurred in Peninsular Malaysia from mid April to June 2010 and bleaching in East Malaysia was reported from mid May to early June 2010. Coral bleaching seems to be increasing in frequency due to the rapidly changing environment and increasing anthropogenic threats.
Some scientists are predicting that coral bleaching will occur annually in the coming decades. While bleaching cannot easily be prevented or stopped, steps can be taken to promote coral recovery after a bleaching event.
Acknowledging this, Reef Check Malaysia has teamed up with the Department of Marine Parks Malaysia to establish a framework response for coral bleaching management. A Bleaching Response Plan is being drafted that will define a set of pre-determined actions to be taken in response to bleaching-related events. It represents an urgent need for collaboration between managers, government, non-governmental agencies and concerned stakeholders to take immediate actions to improve reef ecosystem resilience, aiding recovery from the stress events. The objective is to put in place a simple mechanism to react to bleaching events with appropriate actions.
The response plan will have 4 major components:
1. Early warning system
2. Ground-truthing survey
3. Public awareness and communication exercise
4. Resilience building action plan
The bleaching response plan is a post-occurrence, short term action plan. Our real focus should be first and foremost to mitigate the causes of coral bleaching i.e. reducing emissions of greenhouse gasses that cause climate change. Everyone can help. Simple steps such as switching off electrical appliances when not in use, turning off the tap while you are brushing your teeth, using public transport or car pooling, will go a long way. Even though you might be physically detached from the reefs, you can still do your part to save them from disappearing.
For more information, contact Reef Check Malaysia at firstname.lastname@example.org
|Koh Tao’s First Ever Reef Check Training of Trainers|
|By Reef Check EcoDiver Course Director Nathan Cook
In the week leading up to Christmas, Thailand’s island of Koh Tao & Crystal Dive played host to its first Reef Check Training of Trainers program.
We were joined by Reef Check scientist Suchana “Apple” Chavanich for some of the classroom sessions. It was great having Apple present for part of the course to answer some of the more in-depth questions and provide further information on the role of Reef Check in Thailand and worldwide.
During the course, the participants undertook detailed classroom lectures on organism ID and their roles in the ecosystem before diving on local reefs. During the dives, new instructors were given the reins to manage and coordinate the relevant surveys to confirm they would be capable of handling this role in the future. We also threw some potential problems at students to check their proficiency in addressing and correcting problems.
On the final afternoon we headed to a local dive site, Twins, where our new instructors took control of a full Reef Check survey which has since been submitted to Reef Check Headquarters for inclusion in the worldwide database.
Congratulations to participants in the course including Crystal Dive instructors Nicolas Hebrant & Liran Barkan, Chad Scott of Marine Conservation Koh Tao and Hariharan Lyyappan from India.Comment on this article
|Save the Reefs, Save the Oceans Gala: September 8, 2012|
This year's Save the Reefs, Save the Oceans Gala will be be held September 8, 2012 at the Jonathan Beach Club in Santa Monica, California. The evening will recognize the contributions of our “Heroes of the Reef” each having demonstrated an exemplary commitment to ocean conservation.
Sponsorship opportunities are available. We are also looking for donated items for our live and silent auctions. Please contact email@example.com or 1-310-230-2371 for information.
Proceeds from the gala will fund educational programs for children and the conservation of tropical coral reefs and California rocky reefs.
Details on the 2011 gala can be found at http://www.reefcheck.org/events/gala2011/
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