Two bleached anemones were found on Lord Howe Island (one is shown here), a sign that future monitoring of these reefs is vital.
OUR SMALL VESSEL ROCKS GENTLY back and forth in the southern end of the Lord Howe Island lagoon. A breeze whispers from the south around two rainforest-clad mountains shrouded in mist. Their flanks descend precipitously into the sea.
The view is spectacular, but we barely have time to take it all in. We are faced with a pressing task - to discover Lord Howe Islands own Nemo, the McCullochs anemonefish found only in this tiny corner of the world, and their host anemones.
Tiny corner though it may be, Lord Howe Island has some big designations to uphold. This most southerly barrier reef in the world is listed as a World Heritage Area, and is also protected as a marine park. It lies in the Pacific, 435 miles north-east of Sydney, and 620 miles south of the Great Barrier Reef.
The islands clear waters and surrounding blue lagoon are influenced by both tropical and temperate currents, resulting in an unusual mix of species, including 16 fish found nowhere else on Earth. One, the McCullochs anemonefish, has the smallest geographical range of any of the 29 anemonefish species.
From our vessel, the water below is so clear that it would be possible to study the reef and milling colourful fish just by looking over the side - but wheres the fun in that We are at the first of our survey sites, and marine biologist Jean-Paul Hobbs of James Cook University can barely contain his excitement as he explains the project.
Its simple really, says Jean-Paul. Monitoring all the species on the reef can be overwhelming, so we focus on a single species, such as this anemonefish, which acts as an indicator species.
Global warming can kill corals and anemones, and anemonefish cant survive without anemones. By monitoring this species, we get an indication of how healthy the reef is.
LIKE HARD CORALS, SEA ANEMONES have a symbiotic relationship with a species of algae called zooxanthellae.
The anemone provides shelter for the microscopic algae, which in turn provides carbohydrates to the host as a by-product of photosynthesis. When anemones experience an increase in water temperature, such as that caused by global warming, the food-producing algae may be expelled.
Its the zooxanthellae that provide the anemones bright colours, so when it is expelled the anemone appears pale and bleached, and will eventually perish if the zooxanthellae are not reabsorbed.
Anemonefish populations depend entirely on the availability of suitable host anemones for habitat and protection, so a loss of anemones results directly in a loss of anemonefish.
Occasionally, complete reefs can be affected by an increase in temperature. Known as mass-bleaching events, such phenomena have been reported throughout the worlds tropical waters over the past 5-10 years.
The two most recent occurred in the summers of 1998 and 2002. The Great Barrier Reef was hardest hit in 2002, but the greatest global effect was observed in 1998, with an estimated 16% of the worlds coral reef destroyed.
The response of coral reefs to adapt to an increase in temperature depends on the ability of the zooxanthellae to adapt and acclimatise to warmer temperatures.
A recent project by PhD candidate Laura Wicks of Victoria University of Wellington examined the diversity of zooxanthellae found in corals at Lord Howe Island.
Laura determined that the diversity there is of particular significance with respect to global climate change, because different types of zooxanthellae exhibit striking differences in their susceptibility to temperature increases.
The diversity of zooxanthellae is high at Lord Howe Island, which means that there may be species that can tolerate greater temperature variation, resulting in anemones and corals that are more resilient to changes in temperature, says Laura.
This project does not stop with the research team - the whole Lord Howe Island community is eager to be involved. Lord Howe Islanders have strong environmental values, brought about by living in a World Heritage Area, which in some instances runs generations deep.
In March 2009, the Lord Howe Island Central School, Lord Howe Island Marine Park Authority and three glass-bottomed-boat tour operators conducted the inaugural anemonefish surveys, and are keen to continue the monitoring in future years. They recognise the importance of conserving their reefs for future generations.
Dean Hiscox of Lord Howe Island Environmental Tours says of the tour operators: Without the reef, we would lose both an environmental jewel and also lose our livelihood.
We have a great opportunity to educate visitors about issues such as global-warming, bleaching and unique features of the region, such as the McCullochs anemonefish. Its great to see peoples eyes light up when the message gets through to them.
AND THE MESSAGE IS GETTING THROUGH. Julian Mostert, Principal of the Central School, told me: This project has really allowed our staff and students to learn more through first-hand experiences. We didnt realise that the marine creatures on coral reefs were in so much trouble. Its exciting to have this opportunity to help these reefs survive.
Jean-Paul joins each operator to conduct their first surveys. Peter Busteed from Islander Cruises selects a site. Jean-Paul explains to Peter that the anemonefish are counted first and then the anemones, which can be individually identified because they retract to a gentle touch.
To continue the assessment of Nemos future, the team spends the afternoon collecting juvenile McCullochs anemonefish samples to be used for genetic analysis. As I sit staring into the anemone at the small black and white fish moving back and forth, net and spray bottle of clove oil in hand,
I wonder how this will be possible.
Jean-Paul swims past, separates the small fish from the anemone with a simple hand movement, gives a few quick sprays of clove oil (just enough to make the fish drowsy) and scoops the small fish into his net.
All the tiny fish are collected in this way, and placed in a holding bag.
IN A MATTER OF SECONDS we take a small fin-clip, much like a fingernail clipping. Within a minute the fish has woken up and is returned to its anemone home.
The tiny fin-clip holds the DNA that is the key to the species future.
Back in the laboratory, the genetic analysis will determine the genetic diversity of the population. This information is then used to determine the species ability to adapt to change and, more importantly, to assess their risk of extinction.
As we complete our underwater surveys at the final site, we feel a sense of relief. The prognosis is very good.
The Lord Howe lagoon has some of the worlds highest densities of anemonefish, and is a clear stronghold for the endemic McCullochs anemonefish.
While Lord Howe Island still has an abundance of these fish, the future outlook for the worlds coral reefs is bleak. As the oceans temperature rises with global warming, the frequency and severity of mass bleaching is expected to increase.
However, the establishment of the monitoring program at Lord Howe Island means that local people can keep an eye on their reefs. Working together, scientists, marine-park managers and the local community are striving to ensure the long-term future of this iconic coral reef fish, and ensure that Nemo can always be found.