The first month on Cat Ba Island – getting my bearings

My apologies for the long gap between posts, life has been a bit busy.

I recently began a new position in Vietnam, on Cat Ba Island to be specific.  My first impressions are that this is a damp and precipitous landscape.  I have not seen the sun since I arrived in Vietnam on March 4th.  For Cat Ba Island this means a riotous profusion of greenery tempered by the steep terrain and lack of soil.

Where the northern end of the road terminates

Where the northern end of the road terminates

This is a land where Ymir’s bones lie close to the surface, broken and weathered, their calcium leaking back into the waters from which these precipitous cliffs rise.  The geology is the first thing that strikes you here.  The cliffs have been weathered by millions of years of rain, the ever-so-slightly acid rainwater eating into the ancient limestone creating a mature karst landscape.  Like bones, coral, and seashells, limestone is primarily made up of calcium carbonate, which in other forms makes marble and dolomite.  This is probably one of the reasons this is a place where snail diversity is immense, ranging from tiny frilled creatures more akin to limpets to giant land snails, many of which are still unknown to science.  Snails need lots of calcium to make their shells.

Unknown frill terrestrial snail

Unknown frilly terrestrial snail

Land snail shells collected around the office - and a wasp nest

Land snail shells collected around the office – and a wasp nest

The banded limestone found here is a relic of abundant diatom (a type of plankton) skeletons laid down five hundred million yeas ago and subjected to the vagaries of time.  Limestone, while soft to the chisel and hammer, is a remarkably durable stone at the macro-scale, one of the reasons climbers like it, but at a chemical level it is easily weathered.  We are often told that water has a pH of 7, that is it neutral.  Natural rainwater, we then assume, should also have a pH of 7, but it is closer to 5.6 due to the dissolution of carbon dioxide into the water making carbonic acid.  A pH of 5.6 is about as acidic as a cucumber or an onion for comparison.  Of course, other environmental factors can reduce this tremendously, leading to extremely acidic rain.  Rain falling on the limestone erodes small channels in the rock that look like thumbprints in wet clay.

Rainwater erosion on limestone

Rainwater erosion on limestone

Eventually these concentrate water flow, carving small holes in the stone reducing it to a swiss-cheese like structure with an extremely jagged and sharp exposed surface.  These little caves connect into larger caves.  In these protected, damp environments bacteria grow, exuding waste products and creating hydrogen sulfide that mixes with the water and makes a weak sulfuric acid, increasing the chemical weathering.  This cycle persists, eventually leading to enormous caves.

The airflow in these caves evaporates the mineral rich water tricking through the now porous stone and the calcium carbonate re-solidifies into stalagmites, stalactites, soda straws, and any number of strangely beautiful and complex cave structures.

Caves often form in weak portions of the stone and, eventually, gravity takes its toll and the weakened rocks collapse leaving behind steep spires and fields of slowly eroding boulders.

Limestone spi

Limestone spire in the north end of Cat Ba Island

Cat Ba and Ha Long Bay are examples of a drowned karst landscape, a mature karst landscape that has been flooded by rising waters.  What little soil does form is washed down into the many bays, coves, and channels of the region, leaving little for plants to sink roots into.  In the shallow waters of the bays mangroves find nutrients, in abundance.  Here mangroves are near the northern margin of their range, their numbers restricted and the trees short, making low dense forests.

Gray mangroves on the south western side of the island

Gray mangroves (Avicennia marina) on the south western side of the island

As in many places, the mangroves are in trouble here, often cut down to make shrimp farms.  This leads to reduction in local fisheries, increased erosion, and lack of protection from storm surges and tsunamis.  The local government is taking steps to protect what remains and to, potentially, restore some of the previous mangrove forests.  In the rich mud of the mangrove regions there are numerous animals, among them one of my favorites, mudskippers, amphibious fish that hop about in the mud protecting their little territories.

Mudskipper amongst mangrove roots

Mudskipper amongst mangrove roots

On the cliffs however there are few nutrients and plants grow in what cracks and declivities they can find.  As per many islands there are a number of endemic species, here one of the most commonly seen ones is the Ha Long Cycad (Cycas tropophylla), an ancient type of gymnosperm that looks like a cross between a fern and a palm tree.

Ha Long Cycad (Cycas tropophylla), endemic to a 400km square area, globally rare, locally abundant

Ha Long Cycad (Cycas tropophylla), endemic to a 400 square km area, globally rare, locally abundant

The season here is shifting into spring and some of the trees have begun blooming, among them the hoa gạo or Cotton Tree (Bombax ceiba), so named for the kapok-like fibers that are found in the seed pod.

Hoa Gạo (Bombax ceiba), Cotton Tree in English.  The Vietnamese name translates to "Rice Flower"

Hoa Gạo (Bombax ceiba), Cotton Tree in English. The Vietnamese name translates to “Rice Flower”

 

I still have not seen the little primates I came here to work with, they are few in number and they clamber about on the vertical cliffs like, well, monkeys.

Soon though.

A New Job, a New Voyage, An Endangered Species

The rain has finally come to California, bringing with it the promise of new growth and greenery.  As it rains outside the window I am inside,  surrounded by loosely organized piles of clothes, books, outdoor gear, and laptop peripherals attempting to fit my life into two 20kg bags.  Before I go I need to take care of all those technological tasks our life is filled with as well, back up my computers, transfer my iPhone and iPad to a different computer (Apple, you really need to make that easier to do), and do the final run-through on what I am taking with me.  Despite all this, my mind is only partially on the task at hand.

Several weeks ago I was offered a position working on primate conservation in northern Vietnam and my mind is on the location, the people I will be working with, and the upcoming tasks.

The Gulf of Tonkin - NASA image

Northern Vietnam, Southern China, and the Gulf of Tonkin – NASA image

This is exciting, not in the least because Vietnam, like much of South East Asia, (and Southern China) lies firmly in one of the great biodiversity hotspots of the world.  Northern Vietnam is on the edge of Sundaland, a name for the vast expanse of what used to be land connecting the Southeast Asian mainland to Borneo and the Indonesian islands, now mainly under water and expressed as the Sunda Shelf.  During the last ice age this is thought to have been a broad grassland spotted with mountain forests and laced with broad rivers.  For nearly 100,000 years plants and animals moved back and forth across this landscape, becoming wide-spread and subsequently isolated as the rising seas flooded the lowlands, leaving the complex arrangement of islands and peninsulas we now see.

This exposure and inundation of land in this part of the world has been taking place for a long time.  This combined with the vigorous tectonic activity of the region has led to a wonderfully complex region topographically, and subsequently (or in conjunction) biologically.

Sundaland showing current and proposed past rivers

Sundaland showing current and proposed past rivers (source)

This submerged region is now thought to be the cradle of the Asian population, the “Out of Sundaland Theory”, although there is a competing “Out of Taiwan Theory” as well.  Where I will be working is only loosely in former Sundaland, a melding point between Sundaland and the complex geography of Southern China and Northern Laos.  In any event hominids, and later humans have been exploring and living in South East Asia for a long time, and that span of time has allowed tremendous cultural and linguistic complexity to develop as well.  This is one of the places that our most successful and long-lived hominid ancestors, Homo erectus, lived.

I will be on the edge of this region, just off the coast of northern Vietnam, on the northern margin of the Red River delta not too far from the Chinese border.  The location is Ha Long Bay, a dramatic karst landscape that is both mature and submerged.  The ingredients for a karst landscape are limestone and time, lots of both.  In some parts of the world the only signifying features of kart landscapes are rich soils (lots of cations) and , if it is wet, periodic sinkholes.  Where water is in abundance caves are common, as groundwater is often mildly acidic which erodes the limestone.  Over time continued erosion wears down the limestone bedrock to such a great degree that all that is left are startlingly steep sided hills, separated by flat valleys.  This is a mature karst landscape.  In Sundaland some of these mature karst regions were flooded when the sea level rose resulting in a dream-like landscape that looks like something Hayao Miyazaki would imagine if he were to direct a pirate movie.

Ha Long Bay mature submerged karst landscape (source)

Places like Ha Long Bay are excellent examples of island biogeography.  Islands are often home to endemic species, the tortoises and finches on the Galapagos Islands are the classic example of this, made famous by Darwin.  Animals and plants that make their way to an island, or are trapped by rising seas or continental drift become isolated and diverge from their ancestors.  This is the essence of island biogeography and the recognition of how finch beaks on the Galapagos changed in response to the limited food sources available on the islands helped Darwin to recognize how evolution takes place.  My personal hero in the tale of evolution, Wallace, worked in the submerged island remnants of Sundaland and experienced the same insights as Darwin.  Ha Long Bay is a small area, but has its own endemic species, many of them we probably know little to nothing about.

One we do know of is the Cat Ba Langur (Trachypithecus poliocephalus poliocephalus), a dark haired leaf eating monkey with white heads and brilliant golden furred babies.  They are found only on Cat Ba Island, one of the largest islands in the Ha Long Bay, and are critically endangered.  Critically is an understatement, there are less than a hundred of these primates alive in the world.  And. That. Is. All. There. Are.

Cat Ba Langur on limestone cliffs. [EDIT – the photo I previously had here was of the closely related White-Headed Langur – it was mislabeled as a Cat Ba Langue at the source I found it]

In 25 hours I get on a flight to Hanoi to take part in an effort to both keep these primates from going extinct and to conserve the biodiversity of the island.  There are a lot of moving parts in the project, many partners at all levels, and only a few of us on the ground to keep everything running smoothly.

I’m excited, eager, and somewhat intimated.  I leave tomorrow.