GBR Legacy Expedition

For the last month I have been luck enough to travel from Port Douglas to Cape York at the northern tip of Australia. This research was conducted on board the M.Y. Flying Fish , a Super yacht donated to GBR Legacy for a 3 week research trip.

The boats route on the expedition

The trip aimed to unite researchers, science communicators and media personnel to research, communicate and discover, which corals survived the 2016-2017 coral bleaching events, and what traits were important for survival.

More information to follow soon, but videos and updates can be found on the GBR Legacy site.

 

 

 

Sydney Harbour-ing unknown coral treasures

During bleaching and post bleaching recovery. Photo: Matthew Nitschke

Researchers at the University of Technology Sydney, lead by Ph.D. student Samantha Goyen, are crowd funding to raise money to study the corals of Sydney Harbour…BUT why?

Coral reefs globally are under threat, from climate induced stressors such as coral bleaching and ocean acidification, as well as local pressure such as pollution. This year alone an estimated 30% of the Northern Great Barrier Reef was killed due to warmer than normal waters associated with the El nino event. Consequently, researchers globally are looking for natural refuges for corals – areas where corals can thrive when most other areas are being degraded. Sydney Harbour has the the potential to be one such refuge!

Sydney Harbour is a long way from the Great Barrier Reef but is surprisingly home to scleractinian (hard) corals. Despite the extreme environmental conditions (low temperatures, low light) corals thrive here. Extreme environments may become the ‘norm’ for reefs and act as refuge environments, as coral reefs are at risk from pollution and global warming. Understanding how the Harbour corals are thriving in Sydney could enable us to better predict the future of coral reefs.

This research will inform biodiversity quantification, that is, the microbial communities associated with the corals, that underpins Sydney Harbour’s high conservation value. This project will uncover the Symbiodinium type (symbiotic algae) and the bacteria that are pivotal to coral resilience in extreme environments as the coral holobiont is essential for maintaining coral health and metabolism. How these communities change seasonally and under stress (see lab notes #1) is critical knowledge to understand the survival mechanisms of these hardy corals.

This data will contribute to physiological and ecological models of future coral distribution and function. This is crucial as current modelling is hindered by a lack of knowledge of coral form and function in extremes.

For more information and to get involved please check out the EXPERIMENT page here.

Anemonefish cohabitation

Part one of our research from Hoga, Indonesia has been published in Marine biodiversity. Here is the first part:

Anemonefishes have an obligate association with host sea anemones and normally occur in conspecific groups. Occasionally, heterospecific social groups are observed (Fautin and Allen1997). Here, we report the highest documented frequency of heterospecific cohabitation in the world. Observations on coral reefs around Hoga Island (Southwest Sulawesi, Indonesia) were conducted on the reef crest and slope habitats (3–15 m depth) during July and August 2014, and cohabitation was recorded in the sea anemones Entacmaea quadricolor, Heteractis crispa and Stichodactyla mertensii. Surveys revealed that 55 out of 106 surveyed sea anemones (52 %) were occupied by more than one species of anenomefish; all other observed sea anemones were occupied by only one. The following combinations of anemonefishes were observed: Amphiprion clarkii (adult)—Premnas biaculeatus (juvenile) (1.8 %), A. melanopus (ad.)—P. biaculeatus (juv.) (3.6 %), A. perideraion (ad.)—A. clarkii (juv.) (7.3 %), A. clarkii (ad.)—A. …

The Truth About Nemo

I am again lucky to have a great guest blog from a good friend and great scientist, Maarten De Brauwer. Maarten is a tropical marine ecologist who comes from Belgium and now lives in Australia. Maarten works on the extinction risk of reef fishes, ecology/importance of cryptic marine fauna and has a special interest in Indonesia reefs.

Maarten De Brauwer

Anemonefishes, also widely known as clownfishes, have long since been a favorite in the marine aquarium world. These charismatic and beautiful fish and the relationship with their hosts – sea anemones – have fascinated and amused scientists and aquarium enthusiasts for many years. The box office success of the Pixar movie “Finding Nemo” in 2003 made the fish widely known and hugely popular with the general public. Unfortunately, the message of the movie (wild fish should not be kept in tanks) got lost somewhere along the way and the exact opposite happened: an explosive increase in the trade in “Nemo”.

Amphiprion percula “Nemo”

Clownfish as a species are widely known, but besides Nemo’s relationship with its “anemenemone” and its pretty colours, surprisingly little about clownfish biology reached the general public. Amphiprion percula (= scientific slang for “Nemo”) is only one of the 28 species of anemonefishes found globally. The 28 species are found from the Red Sea all the way to French Polynesia in the central Pacific Ocean, leaving the eastern Pacific and Atlantic Ocean devoid of these beautiful creatures. They can be found as far north as southern Japan and almost as far South as Perth, Australia. Many of the species are endemics; occurring only in a very small area. In the clownfishes’ case the endemic species are often found around small oceanic islands such as Seychelles, Mauritius or Chagos Archipelago.

While the adventures of Nemo and his dad in the Pixar movie were positively thrilling, reality in the case of the clownfish far surpasses fiction. The life of an anemonefish is a big adventure, from start to finish, with lots cliff-hangers and unexpected twists in the plot. After baby clownfish hatch from their eggs, they don’t simply move into their parents’ anemone. Instead, they float on the ocean currents for about three weeks, sometimes travelling up to 400km before settling into a suitable anemone. After moving into their new anemone, they transform from a see-through, wormlike larvae into a colourful miniature version of the adult fish. However, every single one these tiny clownfish will be, without exception, male. As a matter of fact, in any social group of clownfish, every individual will be male except for the largest fish. This dominant fish is female and will only mate with the largest male in the anemone.

            Amphiprion clarkii with eggs

Amphiprion clarkii eggs

An interesting thing happens when this female dies (say, in the unlikely event she gets eaten by a barracuda), leaving the anemone looking very much like an all-male dorm room in a university, a lot of males wanting to mate, but no female to be found. To solve this problem, the biggest male will change sex, turning into the dominant female, with the next biggest male growing bigger and becoming the breeding male. (I’ll leave the human dorm room-version of this to your imagination) In other words, by the time Nemo’s father actually finds Nemo, it should really have been his mother again…which might have confused children and quite a few parents, but could have made for a very interesting movie in my humble opinion.

Unfortunately, not all is well for the anemonefishes, and the future of some species is could be in serious threat. Over the course of the last year, I collaborated with a great number of outstanding scientists to assess the risk of extinction of all 28 species of anemonefishes. The result of this collaboration is a rather large, global database, which tells us a lot of what’s happening with these fish. A few general conclusions can be made about their extinction risk.

The factor that affects the risk of extinction most strongly, is what gives these fish their name; their obligate relationship with a few species of sea anemones. Anemonefish can only use 10 species of sea anemones, and most species of fish will use only 1 or 2 host species. In the absence of anemones, the fish cannot survive on the reef; reefs without sea anemones will not have any anemonefish. Sea anemones are generally rare on coral reefs, an average of less than 0.2% of the area of coral reefs consists of suitable host anemones. Therefore, living in sea anemones might be safer for the fish which are already inside the anemone, but it makes finding a suitable place to live a lot harder for larval fish.

The quantity of host anemones is already small, but currents trends indicate that it is very likely the quantity will decrease even further in the future. Rising sea temperatures, increased acidification can cause host anemones to bleach and perish. Anemone bleaching is the same mechanism as coral bleaching; single celled algae living in the anemone are expelled, after which the anemone loses colour and is hard pressed to catch enough food to sustain itself.  As a result, anemones can shrink, are more susceptible for disease or can die off completely. In recent years, anemone bleaching events have occurred and caused localised disappearance of host anemones and the anemonefish living inside them.

While anemone bleaching might become more frequent in the future, it will rarely occur on a large enough scale to effect the anemonefish species with a wide distribution. The more area a species occupies, the less likely it becomes that the entire area will be affected by bleaching. Which brings us back the many endemic anemonefish species, these are the species that do occupy a small area. In the case of at least three species, it is entirely conceivable that the entire area occupied by the fish is so small, that all of the available host anemones could bleach in one event, potentially removing most of the habitat of the species of anemonefish dependant on it.

A last risk factor, overfishing could also play a role. The popularity of clownfish in the aquarium trade is bigger than ever before, and is likely to increase further with the sequel of “Finding Nemo” planned to be releases in 2016. Overfishing and destructive fishing practices in South-East Asia are known to have caused big declines in clownfish and host anemone populations. While these disturbances are significant on a local scale, they rarely affect the species as a whole. Furthermore, most species of anemonefish can readily be bred in captivity.

So what can we do about these threats? Since the biggest threat, bleaching is hard to remedy, the best we can do at the moment is reduce other stressors (such as overfishing and pollution) by protecting larger areas of coral reef habitat. Bleaching is most often induced by high water temperatures, which are affected by global climate change. So ultimately, the survival of some species of anemonefish, might depend on much bigger challenges, which we can all do small things about, but would take this blog too far away from clownfish.

Finally, try to follow the morale of “Finding Nemo”, don’t keep fish in tanks. And if you do feel the overwhelming need to see Nemo in your own house, make sure it has been bred in captivity and not a poor creature removed from its home anemone on a pristine tropical reef on the other side of the world.

Amphiprion perideraion on the Great Barrier Reef

Coral Reefs in Brazil

I am very lucky to have a guest blog from a good friend and great early career scientist from Brazil,  Carla Elliff. Carla is an oceanographer working with Brazilian coral reefs and the ecosystem services they provide. The main goals Carla is striving to reach are to increase ocean conservancy measures, sustainable options and public awareness.

Carla Elliff

People always talk about how unique coral reefs are as an ecosystem, but sometimes we fail to think how different each reef is to each other. This is particularly true when considering Brazilian coral reefs in comparison to other nations.

Coral reefs in Brazil have four main traits that set them apart from other reefs around the world.

The first are these amazing structures that only occur in the reefs of the Abrolhos bank, called chapeirões. These mushroom-shaped coral pinnacles can reach more than 25 m in height and 50 m in diameter. Why they grow like this and why only in Abrolhos is still quite a mystery.

Figure 1. Sketch of a small mushroom reef from the Abrolhos coastal reef arc, which is commonly found surrounding larger bank reefs.

The second is the low diversity and high endemic rates of these reefs. While coral reefs from the Indo-Pacific Ocean sum hundreds of species, in Brazil there are just under 20 species of reef-building corals. But don’t feel bad for the Brazilian reefs! Although there are few species, the major reef builders are endemic, meaning they only occur in Brazilian waters, which is pretty special. Some of these endemic species have affinities to species in the Caribbean, while others are related to Tertiary coral fauna, which means their closest relatives go way back (between 2.6 and 65 million years) and thus earned them the name of archaic species or relic forms.

Figure 2. Mussismilia braziliensis, an archaic species endemic to the Brazilian coast.

The third trait concerns the important role that incrusting coralline algae has in the construction of the reef structure in Brazil. In fact, the only atoll found in the South Atlantic Ocean, called the Rocas Atoll, is basically composed by crustose algae. This has raised much discussion regarding the accuracy of considering Rocas an actual atoll.

Figure 3. Rocas Atoll

Lastly, unlike most reef systems, in Brazil nearshore bank reefs are surrounded and even filled with muddy sediments from the continent. For most coral species this condition would make the waters uninhabitable, however, remember what I said about the endemic species? These species seem to be particularly sturdy and have developed mechanisms to cope with the higher sedimentation rates that can affect turbidity.

Figure 4. Diving in pea soup at the reef of Boipeba Island, Brazil.

Despite these differences, Brazilian reefs also support an immense biodiversity and provide important ecosystem services. Diving in Brazil is definitely a scuba-lover must!

Sea of Plastic

 

Over the last few years I have traveled to beaches in the Cayman Islands, England, Nicaragua, Cancun, Miami, and now Brazil. Despite being miles apart these beaches have a common theme…..Plastic Pollution! Plastic pollution accounting for 60-80% of marine litter that totals approximately 14 billion pounds each year.  Due to ocean gyres, trash will accumulate in massive islands with an example of the Great Pacific Garbage Patch estimated to range in size from 700,000 square kilometers to more than 15,000,000 square kilometers. 

The primary problem with plastic pollution is that most is not biodegradable which means no natural process can break it down.  Instead, plastics degrade by photodegradation. This means the absorption of photons, typically the wavelengths found in sunlight result in molecular break-down.  A plastic milk jug in the ocean will fragment into smaller and smaller pieces without breaking into simpler compounds; which is estimated to take 1 million years.  Consequently, the ocean is accumulating plastic which breaks down into smaller pieces of plastic called mermaid tears or nurdles.  

 

 

Nurdles can get sucked up by filter feeders, or eaten by other marine life which can potentially be life threatening.  In addition, nurdles can soak up toxic chemicals that can threaten an entire food chain.  The nudles ‘mop up’ chemicals or poisons that are diffuse in the water, which makes them highly concentrated and the nudles potentially toxic.  Larger plastics like shopping bags can also be mistaken as a typical food source and can be consumed by fish, marine mammals and birds. In total, more than a million birds and marine animals die each year from consuming or becoming caught in plastic and other debris.

Below are some pictures taken by a friend who was working in the Philippines.  The pictures are of a Leatherback turtle that was found dead on the beach.  An autopsy of the turtle found two plastic bags: one in the esophagus and one in the stomach which are believed to have caused the turtles death.  Plastic bags can easily be mistaken as jellyfish as highlighted by the Mediterranean Association to Save the Sea Turtle picture shown below.   

 

 

What can we do about the plastics problem?

International action by organizations such as the UN Environmental Program are helping to establishing plans to curb plastic pollution.  Plastic producers are also being held more accountable for recovering and recycling their product after it is used.  However, we can also help with the plastic pollution problem by cutting down plastic consumption in our daily lives.  We can bring our own bag to the store, choose reusable items wherever possible and try to purchase items that have recycled plastic.  If you are anything like me you probably own 20 reusable bags as you end up forgetting them when you go shopping.  However, leaving them by your shopping list or keeping one by your front door will hopefully remind you to take them with you.  Also, small changes like saying no to a plastic straw when you are out reduce plastic pollution. You can also make a commitment to recycling and can decide to take responsibility for your waste and the impact it has on the environment.  If it is in the home, the workplace or an organization set tangible goals to reduce plastic waste generation.  Finally, clean-up a beach! Whether you organize a beach clean-up at your local beach or you just wonder along and collect what you see it all helps to reduce the plastic pollution problem.  

Invisible Coral Flow

Photo Credit: VICENTE FERNANDEZ, ORR SHAPIRO AND ROMAN STOCKER

Whilst researching the boundary layer around corals I came across this amazing photograph by Professor Roman Stocker. The photograph shows the micro flow around corals that is normally invisible. The coral’s surface is covered with thousands of tiny cilia (hair-like structure) that stir the water with their oscillations. The mico flow created helps to mix the boundary layer around the coral with their surroundings, which plays an important role in their physiology, but on a larger scale is also important to ocean health and biogeochemical cycles.

The photograph won the International Science and Engineering Visualization Challenge (2013) through the use of microsclae photography. The coral used was Pocillopora damicornis and the image was created by placing the coral in seawater containing tiny nutrient particles under the lens of a microscope. The slight movement of two coral polyps and the dynamic flow of particles in the surrounding water were captured on video over a 90-minute period.

A single image was then created by superimposing information from the beginning and end of the experimental video to show the coral’s movement and the paths of the particles’ flow.  As Professor Stocker explains, “the red coral surface and gold particle tracks show the coral and fluid flow at the beginning of the experiment, while the purple and blue represent the coral and particles at the end of the period. The presence of the vortex at both points in time indicates that the water flow generated by the coral’s cilia is a consistently robust feature of the microenvironment. The proximity of the dots to one another indicates how quickly water flowed; particles further away from one another indicate faster movement.”

This image shows how much we still have to learn about the ocean and coral. To check out the other winners click here.