Thursday, November 24, 2016

Cuba's Jardines de la Reina


One of the more pristine coral ecosystems in the New World, the Jardines de la Reina, south of Cuba, was named by Christopher Columbus for Queen Isabella. This week, Anjani Ganase, marine biologist, wonders how the opening up of Cuban-US relations will affect the protected marine park that was once Fidel Castro’s favourite fishing ground. 
This feature was first published in the Tobago Newsday on Thursday, November 24, 2016
Follow Anjani on twitter @AnjGanase

Recent discussions between the USA and Cuba have begun to open up relations between the two countries. For the first time in over forty years, we consider the question how opening Cuba’s market might affect the rest of the Caribbean with respect to economic competition and trade deals. For others, there is concern that this dramatic shift in Cuba’s economy will impact its natural environment. Will Cuba be precipitated into the development faux pas experienced by the rest of the Caribbean? Or will Cuba, an observer over these years, be able to learn from everyone else’s mistakes, and be able to progress with future climates in mind? What might they now plan for the next 30 years, this island nation that was allowed to grow differently with long-term isolation.
The iconic Giant Grouper provides one of the most charismatic and important species for marine tourism in Jardines de La Reina National Park. Photo courtesy globalconservation.org

When I was younger, I saw Cuba as a place of exile, a place where political ideology was not the democratic norm. It seemed a place so uninviting because so many people were willing to jump on unstable boats and risk their lives for a different kind of life.  The US embargo in the 1960’s stalled Cuba’s “development,” while the rest of the Caribbean continued building infrastructure, taking on the role of the vacation destination for the US. This fork in the road for Cuba shifted development focus to other forms of economic growth, such as agriculture, but also investment in scientific research, especially in healthcare and conservation.  If there were one advantage to a long-term regime that is pro-science and discovery, it would be this scientific freedom to imagine, research and experiment, a luxury that is rare in the scientific world.



“The future of our country has to be necessarily a future of men of science,” – Fidel Castro 1960

However, this freedom was a trade-off. Where most universities worldwide are heavily supported by government and international institutions as well as have intense cross border collaborations, the embargo has greatly limited Cuban scientists. There is limited connectivity to on-going international research and few opportunities for collaborations, not to mention the difficulty in acquiring necessary equipment. On the other hand, the limited access to technology also made the science creative and inventive.



It is unknown whether the protection of large tracts of marine and terrestrial areas, rich in biodiversity, under Castro occurred through the country’s need or isolation; whether large virgin tracts are the result of being left out of the world market or because of Castro’s genuine love for nature. I confess a particular interest in the protected archipelago 50 km off the south coast of Cuba that is home to the renowned coral reef - Jardines de la Reina (The Queen’s Gardens). These coral gardens were named by Christopher Columbus to honour Queen Isabella.

 
Surveillance of the hundreds of cays and waterways of Jardines de la Reina requires an innovative and cost-effective human and technology-based solution. Photo courtesy globalconservation.org
The protected area is about 2000 km2, an area roughly seven times the size of Tobago. These were also Fidel Castro’s personal fishing grounds. Jardines de la Reina is considered to be one of the last remaining pristine reefs and one of the largest marine protected areas in the Caribbean. Since its declaration as a marine protected area in 1994, the park has been closed to fishing, except for lobster, and restricted use for diving and tour operations with an annual maximum quota of divers. Today, local ecologists team up with international conservation groups, such as Global Conservation, monitoring the health and protection of these coral reefs that is home to a high biodiversity of fish population that is on average of eight times greater than the rest of the Caribbean. Jardines de La Reina is teeming with top predators including grouper, snapper and hogfish, which are generally a targeted species in fisheries (Pina-Amargos et al. 2014). A high diversity and abundance of sharks can also be found in the park, a sight that is very rare elsewhere in the Caribbean today. 

Caribbean Reef Sharks are Critically Endangered and survive only in a few places on earth, one being Jardines de la Reina National Park. Photo courtesy globalconservation.org

Much of the work done by scientists at the University of Havana is focussed on the movement of fish species in relation to their different life stages; it is well understood that the fish could roam large distances in open water, and inhabit different habitats at different stages of development; areas where they may not be protected. Therefore it is crucial to understand when and where they are most vulnerable. Further west along the Cuban coastline is the Zapata swamp, a protected wetland and home to the endemic Cuban crocodile. This location and other surrounding wetlands are likely to house many of these juvenile predators as shown by other studies on coral reef –mangrove connectivity.

Unfortunately, the coral reefs were not immune to the yellow band disease in the 1980s that infected much of the Caribbean branching coral communities, or the loss of the sea urchin, a major grazer on Caribbean coral reefs. Cuban reefs do not reflect the high hard coral cover that was prevalent during the 1970s and 80s, however the remoteness of these reefs and the low impact of nutrients and runoff from land development may have prevented further degradation in the years after, leaving small areas of healthy coral cover. It will be interesting to know how the fish communities have changed in the marine parks over the last 20 plus years, since the protection was established.

As the USA and Cuba begin to open up relations, there are finally opportunities for scientific collaboration and access by the international scientific community. These doors will also give access to business opportunities and visitors on the ground, something that Cuba’s economy may benefit from. However, what is key is whether the government can balance opportunity without compromising conservation. For Cuban coral reefs, even with the best management, there will undoubtedly be some effects on the reefs as accommodations for development occur. Hopefully, Cuba will continue slow and cautious in the face of the rapidly changing world.

For more information:
http://www.nytimes.com/2015/07/14/science/crown-jewel-of-cubas-coral-reefs.html?_r=0

Roman, J., Kraska, J., (2016) Reboot Gitmo for U.S.-Cuba research diplomacy, vol 351, issue 6279


Pina-Amagós et al. (2014), Evidence for protection of targeted reef fish on the largest marine reserve in the Caribbean. PeerJ 2:e274

Thursday, November 17, 2016

Release the Kraken!


In the movie, Clash of the Titans, Zeus unleashes his ultimate weapon when he commands, “Release the Kraken!” What is this monster (pronounced krak-en)? This week, Anjani Ganase, marine biologist, tells us about the oceanic giant squid that has been invoked in other films such as Pirates of the Caribbean. Although none as immense as those described by fishermen of a thousand years ago have yet been seen, who can say what lies in the unexplored deep seas that encircle our world. 
This feature was first published in the Tobago Newsday on Thursday, November 17, 2016
Follow Anjani on twitter @AnjGanase


The Norse legend of the Kraken tells about the mythical sea creature that lived off the coasts of Norway and Greenland.  It is a giant squid that rises up from the deep to crush vessels and pull fishing boats to a watery grave. Some of these stories recounted since the 1200s were documented by the Danish naturalist, Bishop Erik Pontoppidan, as part of his written works on the natural history of Norway (1752-1753). In his tales of the marine environment, he included many accounts of encounters by fishermen with this sea monster, the Kraken. He tells of fisherman who would row far out to fish: out to sea, they would find waters teeming in fish at the surface; and in these locations, they knew that below lay the kraken. The fishermen would harvest as much fish as quickly as possible, and seemed to know that more fish in shallow water near the surface would indicate when it was time to move, for the kraken would be  making its way to the surface feasting on the schools of fish above it.

“… they find that the Kraken is raising himself near the surface and then it is not time for them to stay any longer; they immediately leave off, fishermen take to their oars and get way as fast as they can. When they have reached the usual depth of the place and find themselves out of danger, they lie upon their oars, and in a few minutes after they see this enormous monster come up to the surface of the water, he there shows himself sufficiently...” - Pontoppidan
Hetzel edition of 20000 thousand leagues under the sea. Jules Verne (Public Domain)

In his book, the descriptions of the Kraken by the fisherman closely resemble the giant sea squids except for the sheer size of the creature:

 “…though his whole body does not appear, which in all likelihood no human eye ever beheld, its beak or upper part, which seems to be in appearance about an English mile and a half circumference, looks at first like a number of small islands, surrounded with something that floats and fluctuates like seaweeds. Here and there, a larger rising is observed like sand banks, on which various kinds of small fishes are seen continually leaping about till they roll off into the water from the side of it; at last several bright points or horns appear, which grow thicker and thicker the higher they rise above the surface of the water and sometimes they stand up, as high and as large as the masts of middle sized vessels.”

Today, it is commonly accepted that the giant squid is the kraken that the fishermen described in Pontoppidan’s book. Most of the research is carried out on deceased specimens that have been stranded, from deep sea trawling, from the stomach content of their predators, and from other related species. They can be found in the deep waters of most oceans, feeding on other fish and squid. Their only predators include most famously the sperm whales, known to have bite marks from the giant squid. Other predators include the toothed whales, sharks and swordfish; and it now appears that these creatures are not the top predators of the sea as we imagined previously.

“This animal has another strange property, known by the experience of a great many old fishermen. They observed, that for some months the kraken or Krabben is continually eating and in other months he always voids excrements. During this evacuation the surface of the water is coloured with the excrement and appears quite thick and turbid. This muddiness is said to be so very agreeable to the smell or taste of other fishes, or to both, that they gather together from all parts to it, and keep for that purpose directly over the kraken; he then opens his arms, or horns, seizes and swallows his welcome guests and converts them after the due time by digestion, into a bait for other fish of the same kind.” - Pontoppidan

Today research on these so called sea monsters have slowly turned fiction into fact. The excrement that the fishermen describe may actually be the ink that squid releases, which is a thick mucous fluid composed of melanin. Often considered a smoke screen for a quick getaway from predators, the inky exudate darkens the water and blurs their vision. They can even emit an even thicker and darker cloud of mucus that retains its shape, resembling the squid itself, providing a decoy while the squid swims away. What the fishermen may have thought was a tactic for luring prey was more likely an attempt to make a quick getaway from other threats, including the fishermen themselves.
Giant Squid surfacing to feed on baited squid near the Ogasawara Islands, south of Tokyo, Photo by Tsunemi Kubodera, a researcher with Japan's National Science Museum

To date we still don’t know the global population of giant squids, and it has only been estimated by the sperm whales that feed on them. Not much is known about their hunting and feeding habits. They are considered to be strong swimmers and active hunters, even thought to have organs on their tentacles that emit light to lure in prey. Only one confirmed live encounter showed a giant squid feeding at 900 m depth on smaller squid; this was still some 1300m above the bottom. Their stomach contents also show that they do feed on crustaceans prevalent in the deep-sea bottom, indicating that they are capable of roaming at great depths. The age of these creatures is most uncertain; they are considered fast growing,  and many of the specimens caught might be merely teenagers. Finally, and most controversial of all, is the size of the giant squid. Old records suggest lengths of up to 60 m long, however there has never been any recent record of this. Recent studies have suggested a maximal length of 15m with most observed averaging about 11m; much different to the legends that speak of miles in length.

Ninety percent of our oceans are open-water environments remote from coastal environments. We know so little about the creatures that dwell there and much less about how we may be impacting them. Even these giant squids that are deep ocean dwellers aren’t immune from human activities. More strandings have been associated with exceptionally warm water, as well as from acoustic seismic soundings for petroleum. With the projections of warming waters, we can definitely expect more of these strandings to occur. The surfacing of giant squids may also be indicators of changing pelagic ecosystems under future climate scenarios– ocean acidification and warming temperature. Although they do not have calcium carbonate skeletons, their receptors for movement are calcium carbonate based and can be affected by lower pH levels. Warmer waters would limit the squids’ ability to extract oxygen out of the water column and could cause suffocation. With further science and growing education, it is hoped that we might also conserve these sea monsters of the past as living icons of the deep sea, symbols of ocean conservation and awareness.


References:
Roper, Clyde F. E. and Shea, Elizabeth K. 2013. Unanswered Questions About the Giant Squid Architeuthis (Architeuthidae) Illustrate Our Incomplete Knowledge of Coleoid Cephalopods*. American Malacological Bulletin, 31(1): 109-122.

Guerraa, A., Gonzáleza, A. F., Pascuala, S., Daweb, E. G. (2011). The giant squid Architeuthis: An emblematic invertebrate that can represent concern for the conservation of marine biodiversity. Biological Conservation 144(7):1989-1997

Pontoppidan, E. (1755) The Natural History of Norway



The following images were published in James B. Sweeney's A Pictorial History of Sea Monsters and other Dangerous Marine Life, 1972, Bonanza Books. The kraken are identified as giant squid, and alternately called octopus, calamari, or cuttlefish.







Thursday, November 10, 2016

The Caribbean War against Lionfish


This week, Anjani Ganase, marine biologist, tells us what we need to know about the presence of lionfish on Caribbean reefs. With no natural predators in the Atlantic, lionfish feed voraciously upon juvenile fish that are essential to healthy coral reefs. Introduced carelessly in Atlantic waters, man must take on the responsibility to stem the invasion.
This article was first published in the Tobago Newsday on Thursday, November 10, 2016.
Follow Anjani on twitter @AnjGanase
 
Lionfish in its native home, the Great Barrier Reef. Photo by Richard Vevers, The Ocean Agency, XL Catlin Seaview Survey 2012.
Lionfish Invasion
Naturally present in the Indo-Pacific tropical waters, the lionfish is a common ornamental fish in the aquarium trade. In the 1980s, two species of lionfish - red lionfish (Pterois volitans) and the devil firefish (Pterois miles) the less common of the two - were introduced into the marine waters along Florida’s east coast, a notorious “hotspot” for marine introductions. Lionfish is one of over 30 introduced marine species off the coast of Florida. By the 1990s they expanded their range farther along the east coast with sightings as far north as New York. Fifteen years later, in 2005, there were regular sightings in Bermuda and Bahamas and parts of the Gulf of Mexico. After this, the invasion of lionfish to the rest of the Caribbean accelerated. Lionfish continued to expand southward into the western Caribbean, invading the Greater Antilles, Cuba and Hispaniola, Belize and Mexico and parts of the Central America. By 2010, the invasion continued into the islands of the Netherlands Antilles west of Trinidad and Tobago, and the Lesser Antilles, St. Maarten and Guadeloupe to our northeast. By 2011, Barbados spotted their first lionfish so its southward track was inevitable, and Tobago had its first confirmed sighting in 2012. Although lionfish have invaded most of the Caribbean, experts don’t expect that they would be stopping here. Considering their environmental range, they predict that they will continue to spread further south along the coast of South America, to Guyana, French Guinea and eventually to Brazil inhibited only by colder waters. However, with warming climates they might even expand further.

Lionfish Strategy
In their native habitats, lionfish are uncommon and relatively unknown. On the Great Barrier Reef, an encounter with a lionfish was one to check off; but sighting these got old pretty quickly when they saturated your reef view. Lionfish are relatively rare in their native region in the Indo-Pacific; and they’re generally not considered a preferred meal because of their venomous spines. Adults are hardly considered prey, except by Cornetfish in the Indo-Pacific and Nassau Groupers in the Bahamas.

On the other hand, lionfish are incredible hunters. In one study that compared the hunting strategies and prey choices of lionfish in the native and introduced territories, they are generalist feeders, feeding typically on juvenile and small fish species. Their banded coloration helps them to blend in while hunting. They mostly hunt in low light, at dawn and dusk or overcast conditions, which is common for most predators including sharks. During daylight, they hide in cryptic environments such as under rocky crevices. They have two main strategies for hunting. They fan out their pectoral fins - similar to how batman fans out his cape before he descends on the bad-guys – to herd and corner small fish. Lionfish also have a blowing strategy where they propel water onto the prey to confuse and disorient them. Although it was found that the techniques and feeding times did not change much between the regions, it seems that the success rate is higher in the Caribbean because they are not perceived as a threat. In the Caribbean, they have been able to feed on larger fish. The blowing technique also seems to be unnecessary, as prey is more easily caught. Pacific fish species seem to be more aware of their presence.

The broad range of tolerance to different environments, occurring across significant temperature and depth ranges, has facilitated lionfish presence in the Caribbean. Lionfish can be found down to 100 m deep. They also mature quickly, have fast reproductive rates and long life spans.

Ecological Impacts
What lionfish feed on is the main cause for concern in the Caribbean. One group of fish – the parrotfish – are important grazers of macro-algae on Caribbean reefs and crucial in maintaining low cover of algae, which are the main competitors against hard corals for space.  Lionfish can feed heavily on the juvenile populations of these crucial herbivores; and on coral reefs where populations of parrotfish are already severely compromised the impacts can be disastrous for the health of our coral reefs. They also undermine the predator population by feeding on the already heavily depleted juvenile populations of groupers and snappers, reducing their recruitment levels on coral reefs, even as they compete with them for food.

What eats Lionfish
Island states have taken up the responsibility of hunting and killing lionfish in an effort to limit their populations at least within the diving limits in shallow coral reef environments. Special tools were made: a polespear and a canister were designed to kill lionfish safely while minimising damage to the reef and other marine life. The spears have to be used in close range with the lionfish. At this time, lionfish seem to be unaware of humans as a threat; but don’t miss, because they’re also quick learners. In the Bahamas and other countries throughout the Caribbean, lionfish tournaments have been organised in an attempt to cull their populations, while creating the opportunity to monitor lionfish size, numbers and distributions. Once enough are caught, the lionfish can be used in culinary competitions, and people can learn how to safely prep this fish for eating. There is a lionfish cookbook produced by REEF.org and is available on Amazon.


Invasive lionfish cruising in the daylight on the Belize Barrier Reef. How many can you see? Photo by XL Catlin Seaview Survey, Global Reef Record.

What can we do to restore balance in our marine ecosystems? The observations that Nassau Groupers were feeding on lionfish occurred within one of the best marine reserves in the Caribbean, where the grouper populations are in the top one percent compared to the rest of the Caribbean (Mumby et al. 2011). Unfortunately, groupers are delicious food fish for humans; and healthy grouper populations may be as unlikely as finding another readily available bio-control on lionfish.

Unless we drastically curb the high levels of overfishing occurring throughout the Caribbean by setting up marine protected areas and regulating fisheries, lionfish will continue to be a threat to our coral reefs. Properly managed marine protected areas offer the best solution to many of the problems of the marine environment, including a natural means of curbing lionfish. Protected coral reefs will be more resilient to ecological and human induced changes.

References:
Schofield , P. J., (2010), Update on geographic spread of invasive lionfishes (Pterois volitans [Linnaeus, 1758] and P. miles [Bennett, 1828]) in the Western North Atlantic Ocean, Caribbean Sea and Gulf of Mexico Aquatic Invasions (2010) Volume 5, Supplement 1: S117–S122
Mumby PJ, Harborne AR, Brumbaugh DR (2011) Grouper as a Natural Biocontrol of Invasive Lionfish. PLoS ONE 6(6): e21510. 

Cure, K. Benkwitt, C.E., Kindinger, T. L., Pickering, E. A., Pusack, T. J., McIlwain, J. L., Hixon, M. A. (2012) Comparative behavior of red lionfish Pterois volitans on native Pacific versus invaded Atlantic coral reefs, Marine Ecological Progress Series, Vol. 467: 181–192.
Morris, J.A., Jr., and P.E. Whitfield. 2009. Biology, Ecology, Control and Management of the Invasive Indo-Pacific Lionfish: An Updated Integrated Assessment. NOAA Technical Memorandum NOS NCCOS 99. 57 pp.


 



Thursday, November 3, 2016

What Coral Reefs tell us about Climate Change


This week, Anjani Ganase, marine biologist, shares new knowledge about Australia’s Great Barrier Reef. With a relatively newer history, Caribbean reefs and first peoples may have information important to survival on our islands; it’s time to observe and research our own environment and record the traditional stories. This feature was first published in the Tobago Newsday, on Thursday November 3, 2016.
Follow Anjani on twitter @AnjGanase

The Great Barrier Reef (GBR), one of the largest natural structures on planet Earth, is visible from space. This natural wonder is about 2300 km long and 344 400 km2 in area, larger than the UK, Switzerland and The Netherlands combined. It is one of the most diverse ecosystems in the world, home to as many as 6000 marine organisms, including species of corals, invertebrates, fish, marine mammals, sharks and turtles.  The reef is also ancient, over 500,000 years old; over this time the edge of Australia’s continental shelf and the reef connected to it has changed with the fluctuating levels of the sea.
 
View of a section of the Southern Great Barrier Reef taken by satellite. The barrier reef marks the coastline of Australia during the last glacial maximum. Image source: NASA/GSFC/LaRC/JPL, MISR Team.
Although the modern Great Barrier Reef is roughly 20,000 years old, the first scientific observations of this reef were only a couple hundred years old, and in this time marine scientists have uncovered a wealth of knowledge about the ecosystems that lay beneath the waters. The advent of underwater diving technology has served to record marine life. With satellite imaging we are able to record the Earth’s changes even underwater. Today, we are able to observe and assess changes in the coral reef community patterns and health of the Great Barrier Reef over time; we can even predict how we affect the reef in the future. However, this story is not about the present, but the past, the beginning of the time when man first made observations of the Great Barrier Reef.

Although Captain James Cook takes the credit for discovering the Great Barrier Reef in 1770, he only stumbled upon the reef when the Endeavour ran aground near Cape Tribulation in the northern part of the GBR. He was sailing his ship along the eastern coastline of Australia, unaware of the barrier reef located to the east. Years later, the naturalist Charles Darwin, carried out scientific exploration of coral reefs from aboard the H.M.S Beagle but for some reason he did not focus his efforts on the GBR. Instead he concentrated his learning on the many other coral reef islands and atolls in the Indian and Pacific Oceans. He classified coral reefs based on their structural formations – atolls, barrier and fringing reef – and theorised on the formation of coral reefs based on growth formations and spatial distribution patterns of different reef building “polypifers.”

“ I must first observe that the reef-building polypifers, not being tidal animals, require to be constantly submerged or washed by the breakers. I was assured by Mr. Liesk, a very intelligent resident on these islands, as well as by some chiefs at Tahiti (Otaheite), that an exposure to the rays of the sun for a very short time invariably causes their destruction.” – Darwin (1842)

His observations that corals thrived in a limited depth range in the shallow clear waters surrounding these islands allowed him to come up with the theory that coral reefs form and evolve over time based on uplift and subsidence of deep sea mountains and the movement of the earth’s crust. In a stable scenario, fringing reefs can form around the island. An island that is being uplifted will carry with it the attached reefs above the water’s surface. The inability of the reef to survive above the water leaves a white limestone ring around the island. On the other hand, as the island subsides then the reefs continue to grow upwards in order to maintain the suitable water depth and thereby form a barrier reef around the island with a lagoon system. Eventually the island becomes completely submerged leaving the atoll ring of growing coral reefs and the lagoon. Eventually the coral growth can no longer keep up and soon the whole ecosystem submerges.
 
Atoll of French Polynesia, showing the ring of reefs remaining after the island has subsided below the water. Image source Google Earth, LandSat
Darwin determined that the formation of the Great Barrier Reef was similar to the barrier reefs formed around the oceanic islands based on the subsidence of these islands. However this was not true in the case for Australia’s reef.  It is now thought that the formation of the GBR resulted from sea level rise about 7000 years ago following the last ice age (glacial maxima).

Today, the theory of sea level rise and formation of the Great Barrier Reef has been confirmed by science. During the last Ice Age (glacial maxima), the sea level was much lower along the coastlines around Australia. The Queensland coast occurred where the barrier reef exists today and the coral reefs fringed this coastline and outer continental islands. The sea level rose owing to the warming atmosphere and melting glaciers, the low lying lands by the sea were inundated and formed what is now the Great Barrier Reef Lagoon and the present day coastline.

Knowledge of this phenomenon was well understood by the first peoples of Australia  - the Aboriginal societies who resided in Australia for over 50,000 years after arriving from New Guinea during the lower sea levels. The Aboriginal tradition of story telling allowed stories about the environment, geography and ecosystems to be passed down from one generation to the next. These stories are elemental to the aboriginal culture and crucial for their survival. Many modern scientists regarded verbal stories as unreliable, because of the level of embellishment and alteration that might be incurred as they passed from one generation to the next. However, for the Aboriginals these were not merely stories, but accurate information about the land and sea essential to their survival. And so, for 7000 years, these stories of the sea level rise were factual and accurate. A recent study showed that the comparison of 21 independent stories of aboriginal communities throughout Australia, correspond with the scientific findings surrounding the timing of the sea level rise and the rate at which the sea level rose based on the bathymetry assessment of different areas (Nunn & Reid 2016).

One example comes from the Gungganyji people who used to live in what were coastal plains in the Northeast Australia, between Cairns and the current location of the Great Barrier Reef.

“…the barrier reef was the original coast here at a time when a man called Gunya (Goonyah) was living here. Having consumed a customarily forbidden fish, the gods caused the sea to rise in order to drown him and his family. He evaded this fate by fleeing to the hills but ‘the sea ... never returned to its original limits’ (Gribble 1932, 56–57; Nunn & Reid 2015)”  
It reminds us that although we observe our ecosystems today with scientific eyes and technology, what we observe about our natural world must be shared and passed on through scientific records or cultural traditions. Our stories are essential for our survival, which are intricately intertwined with the health of our environments.


References:
Darwin, C. R. 1842. The structure and distribution of coral reefs. Being the first part of the geology of the voyage of the Beagle, under the command of Capt. Fitzroy, R.N. during the years 1832 to 1836. London: Smith Elder and Co.

Patrick D. Nunn & Nicholas J. Reid (2016) Aboriginal Memories of Inundation of the Australian Coast Dating from More than 7000 Years Ago, Australian Geographer, 47:1, 11-47.