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.

Tar Pits, Dung Beetles, and Megafauna

Today Los Angeles is a city with a reputation for excess, dominated by cars and actors, and there is a reason for this.  Money.  Money in the form of oil.  The combination of oil and money led to the nascent fossil fuel industry teaming up with the budding car industry in the early 20th century to sabotage the successful street and rail car industry in the Los Angeles basin.  Money led to loose laws which led to crime, gambling, and guerrilla movie studios moving into the LA area, searching for places that were outside the influence of the film establishment of the times.  All of these things are interesting, but without the oil it is unlikely Los Angeles would have taken the trajectory it did.

Oil Fields, Signal Hill, Los Angeles 1914

Oil Fields, Signal Hill, Los Angeles 1914 – source: National Geographic archives

Oil is usually found deep under ground, but the greater Los Angeles area up through the Santa Barbara area is one of a few places in the world where oil is not just close to the surface, it is on the surface, bubbling in cold pits of bitumen, also known as asphalt and tar.  This asphaltum has been important to humans for as long as they have lived in the region.  In the past it was primarily used to waterproof boats, water carriers, and cooking vessels or as an adhesive.  Now, of course we use it to make a whole range of products from gasoline to Vaseline, rubber, plastics, pantyhose, parachutes, paint, detergents, antifreeze, golf balls, and more.

Bitumen occurs where vast amounts of living material (plankton, diatoms, or plant material usually) were deposited in a quiet anaerobic environment, such as a lake or sea floor, and left alone for a long, long time.  In essence, it is liquid coal.  Coal beds are sometimes repositories for incredible collections of fossils.  These ancient remains and offer a window into the deep past, but for a window into the more recent past we need something a little different from coal.  Bitumen provides one of the best preserving agents for more recent remains.

Near Hollywood there is a famous bitumen pit redundantly named the La Brea Tar Pits (literally “The Tar Tar Pits”).  Between approximately 38,000 years ago and 11,000 years ago the La Brea Tar Pits were very active.  An enormous variety of animals and insects were lured to the waters of what appeared to be a rich wetland and were trapped by the sticky tar that lay beneath the shallow layer of water.  A few posts back I brought up the fact that condors are representatives of an extinct assemblage of fauna.  The La Brea tar Pits provide a window into that now extinct assemblage.  Los Angeles was a land of giant bears and jaguars, pygmy pronghorn antelope, camels, mammoths, dire-wolves, great birds of prey, giant ground sloths, and numerous other animals.  

Mural of the La Brea Tar Pits during the Quaternary

Mural of the La Brea Tar Pits during the Quaternary

Animals trapped by the sticky tar aroused the interest of predators and scavengers which were themselves trapped by the tar.  Herbivores, carnivores, mammals, birds, and insects all fell prey to the tar pits and many of them have been preserved in astoundingly good condition.

Pygmy Pronghorn (Capromeryx minor)

Pygmy Pronghorn (Capromeryx minor)

Along with the large animals is one of the best collections of preserved insects in the world.  Most people know that insects are important in a sort of general way.  In recent years honeybees have been in the news quite a bit and their importance in maintaining our food supply has reached the mainstream audience.  I’ve mentioned the importance of both ladybugs and dragonflies, but these are iconic and popular insects, very much in the public eye.  There are many other insects that have an importance far beyond what their diminutive size would indicate.  One of these is the dung beetle (Scarabaeinae).

Until recently much of the planet was home to a wide range of large animals, grouped into the catch-all term “megafauna”.  This is a generic term for any animal massing more than 45-100 kg (100-220lbs).  Most of the recent megafauna of each continent (with the exception of Africa) went extinct shortly after humans reached the respective region.  Here in North America we had great mammoths, elephant relatives, standing 4 meters (13 feet) tall at the shoulder and weighing 9 metric tons (10 short tons).  You can walk under the tusks of the mammoth skeleton in the La Brea Tar Pits, reach your hand up as high as you can, and the tusks are still out of reach.

Colombian Mammoth (Mammuthus columbi)

Colombian Mammoth (Mammuthus columbi)

Numerous types of ground sloth roamed the area, including both the Shasta and Harlan’s Sloths.  Harlan’s Ground Sloth was not the largest and even it stood 3 meters (10 feet) tall and weighed more than a ton.

Harlan's Ground Sloth (Paramylodon)

Harlan’s Ground Sloth (Paramylodon)

The Antique Bison, some 15-25% larger than modern bison roamed the region,

Antique Bison (Bison antiquus)

Antique Bison (Bison antiquus)

And there were, or course predators of all sorts.  Dire Wolves are particularly well represented in the La Brea Tar Pit fossils.

Dire Wolf (Canis dirus) skulls.  One panel of a 3-panel display.

Dire Wolf (Canis dirus) skulls. One panel of a 3-panel display.

There were large numbers of these animals and, like all animals, they had to eat.  The larger the animal, the more it eats.  Modern African elephants eat 100-300kg (220-660lbs) of food per day, so it is reasonable to expect that the Colombian mammoth would eat at least that much per day, if not more.  Then, just on the herbivore side of things, there were the giant ground sloths, horses, camelids, bison, elk, antelope, peccaries, deer, and numerous other species.  Additionally there all the predators; giant jaguars, sabre-toothed cats, dire wolves, American cheetahs, bears of all sorts, including the giant short-faced bear, and more besides them.

All animals must eat, and everything they eat must come out eventually.  This is something we don’t really think much about: what happens to all the animal dung?  How much of it was there?

We don’t really have any good idea just what the animal numbers were like in the past, but we do have a very good idea of the numbers of another kind of modern megafauna.  Cows.  The numbers of cows in the US probably only represent a middling-small portion of the total amount of large megafauna in the US portion of North America, but they give some insight into the kinds of numbers we are talking about when it comes to dung quantities.

The 2006 article by Losey and Vaughan provides some insight to those numbers.  Each cow can produce approximately 21 cubic meters of waste per year, that’s a volume roughly equivalent to 1.3 VW buses worth of dung per year per cow.  In 2004 there were nearly 100 million head of cattle in the US, that means more than 2 billion cubic meters of poop per year, just from cows… I’ll let that image settle in.  For comparison that’s enough to cover  Manhattan to a depth of about 70 feet (21 meters) or Disney World to about 60 feet (18 meters) in cow manure every year (in other news: Disney World is larger than Manhattan).  That’s just from the cows and just the ones in the US.

What happens to all that crap?  Enter the humble dung beetle.  For the portion of cattle that are fortunate enough to be in fields, dung beetles take care of the waste.  According to Losey and Vaughan each year dung beetles save ranchers $380 million dollars in clean-up costs.  A 2001 article by Michelle Thomas indicates that without dung beetles each year we would find 5-10% of each cattle acre unusable due to dung pile-up.  Dung beetles are so important that foreign species of dung beetles have been imported to the US and elsewhere for use in areas that experience heavy livestock use.

Dung beetles range in size from just a few millimeters to several inches in length.  Their size is dependent on the size of the dung they have to deal with.  Currently Africa has the largest land animals and the largest dung beetles.  North America used to have an enormous range of very large animals with correspondingly large droppings.  As you might expect there were some very large dung beetles living here to take care of those droppings.  The large beetle on the left is an extinct giant water beetle similar in size the the large, extinct dung beetles.   This beetle is about 2 inches (5 cm) long.

Different species of dung beetles found in the tar pits.  The large one is extinct.

Different species of small dung beetles found in the tar pits and an extinct giant water beetle that is about the size of the large extinct dung beetles.

Ecosystems are delicate things, subject to trophic cascades, as I have previously mentioned, full of unexpected consequences and side effects.  Most of the great predators in North America died out when the large herbivorous megafauna became extinct.  Scavengers also suffered, amongst them the dung beetles.  All the large dung beetles in North America swiftly followed the rest of the megafauna into extinction.  Currently in North America the dung beetles are small, more like the insects to the right in the image above than the large tan one (you can check out photos of them here).

For many people the response to this is a shrug of the shoulders, but the effects of these beetles going missing had a tremendous effect on the ecosystem, in particular on plant growth and distribution.  We don’t know, and probably will never know how great an effect their absence had.  Dung beetles, the Scarabaeinae, are extremely important ecosystem engineers, gathering fresh dung and burying it as a food source for their developing young.  By doing so they fertilize and aerate the soil, speeding up the cycle of nutrient return by putting the nutrients in a safe place where the plant roots can get to them and where they are less likely to be washed away by rain or desiccated by the sun and blown away.  In addition, dung beetles are important in limiting the spread of diseases and parasites by removing fly and pest breeding sites.

Understanding the details of the world, the interactions, the interconnectedness, the causality of it is difficult.  When we look at the present we have the fine resolution, but lack a context.  When we look at the past we establish a context, but lack the fine scale resolution.  When we look to the future, as we must, we need to be able to combine the insights of the past and the present to predict the consequences of our actions.

Hopefully we are getting better at this, but I cannot help but look at connections like that between the mammoth, dung beetle, the dire wolf, the distribution of plants, and the radiating effects of that interleaving and wonder what vital link, or set of links, we are failing to see right now and what what will mean for our future.

The Archives at the La Brea Tar Pits

Archives at the La Brea Tar Pits

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Apologies for the multiple posting.  I made an edit using the WordPress App on my iPad and it deleted the original post.  I had to restore it and repost.

The Beneficial Lady Beetles: Good Luck Bugs or God’s Little Cows

J.B.S. Haldane, one of the founders of population genetics, is credited with saying, “If one could conclude as to the nature of the Creator from a study of creation it would appear that God has an inordinate fondness for stars and beetles.”  Like most quotes attributed to famous people, it is probably apocryphal, but the point is valid.  There are a lot of Coleoptera species in the world, not as many as there are stars in the sky, but 1 out of 4 animal species in the world is a beetle of some sort.

Many people experience an inordinate queasiness around insects and other arthropods.  There are a few species, however, that rarely elicit distaste.  Of these the Coccinellidae or  Ladybugs (also called Lady Birds and Lady Bird Beetles) are particularly adored.  The most iconic of these are the jewel-like red and black spotted types, of which there are many.  All told there are some 5,000 species of ladybugs around the world, not all of which are red, around 450 in North America, and approximately 175 species in California alone.  All ladybugs share the endearing, rounded shape that their name, Coccinellidae (meaning “little sphere” – Note: some sources suggest that this name means “scarlet”), derives from.  These are primarily solitary little beetles that are found nearly everywhere there a lot of plants, especially in gardens, fields, grasslands, and shrublands.

Convergent Ladybug (Hippodamia convergens) on manzanita leaf

Convergent Lady Beetle (Hippodamia convergens) on manzanita leaf

The rounded shape that gives ladybugs somewhat of a bumbling appearance is actually highly effective armor to protect them from ants.  “Why do they need protection from ants?” one might ask.  Well, contrary to their appearance, they are fierce and merciless predators, specializing in aphids.  Hungry ladybugs will eat a wide variety of insects, but to reproduce they must eat aphids and eat large quantities of them.  An adult Convergent Lady Beetle (Hippodamia convergens), a common and easily identifiable ladybug found in the Americas from Canada to northern Bolivia, eats 40-75 aphids a day with the larvae eating only slightly fewer.  Aphids have a special relationship with ants.

Aphids by themselves are small, defenseless, and relatively harmless, but, as any gardener or farmer knows and fears, they can very quickly reach immense numbers.  Aphids live off of plant sap, sinking their mouthparts into soft plant tissue like miniature vampires.  Plant sap is high in sugars that the aphids excrete in the form of honeydew.  Ants, like many animals, have an affinity for sugar and collect the sweet honeydew from aphids, in some cases treating them not so differently from the way we treat free range cows.  In exchange for honeydew the ants protect the diminutive aphid herds from predators.  Predators such as the voracious and heavily armored ladybug.

Farmers and gardeners have a particular fondness for ladybugs as they can potentially save a whole crop from devastation.  The name “Ladybug” or “Lady Beetle” supposedly derives from vast numbers of ladybugs descending on pest infested fields after villagers prayed to the Virgin Mary to protect their crops.  In Germany one of the names was Mary’s Chicken, in Sweden The Virgin Mary’s Golden Hen, in Spain Gods Little Cow, in Turkey they have the name Good Luck Bug, and in Yiddish they are called Moses’s Little Cow.  In Russia seeing a ladybug indicates that a wish will soon be granted or is an indication to make a wish.  Before Christianity took over northern Europe their name was tied with the Norse goddess Frejya rather than with Mary.  Nearly all the names for ladybugs indicate how well respected and loved they are, though there are a few names reflect the burning aspect of the chemical defense they use to deter larger predators.

The Convergent Lady Beetle is particularly favored by farmers in the US as a natural pest control method.  Despite their solitary nature one acre of alfalfa suffering from an aphid infestation can support up to 50,000 ladybugs by Dr. Kenneth Hagen’s estimate.  Many farmers take preemptive steps to control aphid infestations by releasing ladybugs in bulk, purchasing buckets containing between 70,000 and 80,000 individuals per gallon.

Convergent Ladybug (Hippodamia convergens) in a hibernation swarm.

Convergent Lady Beetle (Hippodamia convergens) in a hibernation swarm.

If ladybugs are solitary, how does one collect 70,000 of them?  They migrate; I’ve mentioned insect migration before, but this is not the extraordinary long distance flight of dragon flies or monarch butterflies.  This is a short migration up into the hills and mountains where the ladybugs cluster in protected areas and wait for the weather to warm up.

Ladybugs do not fly if the temperature drops below 55ºF (13ºC) and the Convergent Lady Beetle spends the cooler months in diapause, an insect analogue to hibernation.  In California, Convergent Lady Beetles living in the Central Valley head up into the Sierras while those closer to the coast find local hollows and protected areas to gather in.  They often show fidelity to specific sites and, in the Sierras, can gather in vast numbers.  Individual sites can have as much as 500 gallons of ladybugs, or more than 37 million individuals.  Collectors scoop thee ladybugs up and sell them to agriculturalists around the country.

In the coastal portions of California the distances the ladybugs travel to wintering sites is not as great and they do not gather in the same density.

Hippodamia convergens in Redwood Regional Park

Hippodamia convergens in Redwood Regional Park

One place to see Hippodamia convergens gathering is in Redwood Regional Park in Oakland.  There is one spot that they return to, a glade near one of the streams.  They coat the low growing and dead vegetation, branches, and logs in an intermittent film of slowly moving red gems.

Hippodamia convergens on dead vegetation

Hippodamia convergens on dead vegetation

In some spots they clump like globs of foam stuck to old hemlock stalks, in other areas they gather on lichen covered logs.

Hippodamia convergens on log

Hippodamia convergens on log

They are not completely dormant.  If you sit and watch them for a few minutes you will see them slowly mill about.

Hippodamia convergens on twig

Hippodamia convergens on twig

In a few places they form a nearly even coat over branches.

Hippodamia convergens covering a branch

Hippodamia convergens covering a branch

In other spots they cluster between the stalks of old flower-heads.

Hippodamia convergens on flower head

Hippodamia convergens on flower head

Finding these conglomerations of ladybugs is particularly exciting, in part as it is so shocking even when you are expecting it.  We have so few opportunities to see large numbers of wild animals in their natural environment any more that when we do it is particularly impacting, especially if it is of a type of animal we usually see as solitary individuals.  The ladybugs are also very pretty, which is always a bonus.

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Macro photos taken with a 70-300mm lens and kenko macro-tubes at a high ISO due to the late time of day and shade.

Plant Defenses – myriad strategies

Plants, as you might imagine, devote a great deal of energy to defending themselves from predators.  We humans have a natural bias towards animals, creatures that are like us in that they are mobile and respond to stimulus on a timescale similar to ours.  Plants operate, with a few notable exceptions, on a slower timescale, but this in no way should be taken to imply that they are any less interactive vis-a-vis their surroundings.

Plants react to light and dark, sense gravity, moisture, nutrients, and toxins; some can “feel” other organisms (Venus fly traps for example) or “hear” sounds (sensitive plants).  One thing all organisms must cope with is predators and competitors, and all organisms need defenses against these threats.  Plants are no different in their needs, but they are largely immobile, so some of their defenses tend to take a different form than they do in animals.  Surprisingly, their defenses are not as different from animal defenses as one might expect.  I would break plant defenses into three broad categories: chemical, physical, and co-optive.

Chemical defenses often involve toxins of one sort or another or pungent aromas.  Some of these we assiduously avoid, such as certain members of the Sumac (Anacardiaceae) family like poison oak (Toxicodendron diversilobum) and poison ivy (Toxicodendron radicans) due to the allergen urushiol found in the sap.  Other plants using chemical defenses we consume with great relish, many of our foods and spices, for example, derive their strong flavors from the defenses the plant manufactures to deter herbivorous predators.  Mints (Lamiaceae), rosemary, cinnamon, peppers, and onions are good example of common foods we consume that utilize strong chemical defenses.  Other chemical defenses we find recreational and/or medical uses for; ephedrine from plants in the Ephedra family, THC from Cannibus, and cocaine refined from alkaloids found in the coca family (Erythroxylaceae) all have enormous economies reliant on them.

Coca cultivation in Bolivia near Coroico

Coca cultivation in Bolivia near Coroico

Chemical defenses are enormously interesting and extremely sophisticated, but they are largely hidden from us until we are affected by them.  This is part of the reason why eating unfamiliar plants is so dangerous, there are few good ways to determine if a plant is edible upon first encounter.

Physical defenses are the most obvious to us, especially when they come in the form of thorns and barbs, but those defenses barely scratch the surface of the types of physical defenses plants can employ.

An impressive but unsubtle defense - Ceiba speciosa in the Bolivian Amazon

An impressive but unsubtle defense – Ceiba speciosa in the Bolivian Amazon

Sharp pokey bits may defend plants against larger herbivores and chemicals help to protect them from insects or pathogens, but other plants themselves can be, if not predatory, at least detrimental to large trees.  Lianas and other climbing plants, epiphytes, parasitic plants, and even other large trees may need to be defended against.

Strangler fig (Ficus spp.) overwhelming a palm tree's defenses - Bolivia

Strangler fig (Ficus spp.) overwhelming a palm tree’s defenses – Bolivia

The photo above I find particular interesting as the palm tree being overwhelmed by the strangler fig usually has an effective counter to this sort of attack.  Palm trees and tree ferns both allow their old fronds to droop as they age, sheathing the trunk and providing a structure for climbing plants to adhere to.  Eventually these canny plants shed their dead fronds, and with them the uninvited plant guests that have taken up residence.  Many trees employ a similar strategy, eucalyptus and madrone have smooth bark that regularly sloughs off in strips.  The combination of smoothness and shedding makes it difficult for other plants to gain purchase.

Strangler fig is a generic term for a wide variety of tropical fig trees sharing a similar life strategy.  These are the “matapalo” or killer trees.  Rather than growing from the ground and climbing up these trees co-opt animals to carry their tiny seeds through the canopy.  A small portion of these seeds wind up in a place like the crotch of a branch or a broken limb where organic material has built up.  The young fig sends dangling roots down from the canopy in search of nutrients, eventually reaching the ground and transitioning from a vine-like life style to a more tree-like life style.  More and more ground-seeking tendrils make their way downwards, eventually ringing the host tree and strangling it.  As this happens the strangler fig uses the original host as a scaffold and sends its own canopy high enough to overshadow the unfortunate host.  The palm tree in the photo above was underneath a tree the strangler fig took root in and had the misfortune to be attacked from above rather than from below.

Color is an oft overlooked plant defense, the role of which is still being debated.  I don’t mean fruit color, that is blatant advertising and animal bribery.  The color and pattern of the leaves and trunk of plants may serve as defense against predators.

The most familiar example of this is variegation in leaves, that is the white or colored mottling seen most often in ornamental plants, but also occasionally found in the wild.

Variegated hibiscus leaf. Source

Color mottling in leaves is often a symptom of nutrient deficiency, insect predation, viral infection, or genetic chimerism (expression of more than one genetic sequence in a single organism).  In most of the above cases this indicates poor health in the plant, and a plant in poor health makes for an unappetizing meal.  Some plants seem to capitalize on this and mimic the effects of various types of poor health (eg. false leaf damage and variegation) to trick predators into avoiding what appears to a be an un-nutritious meal(1)(2).  Bark color, whether natural or as a result of mutualistic lichen growth may be a predator deterrent as well, as lighter colors may make predators more visible to other predators higher up on the food chain.

Before moving on to animal co-option I should mention one other strategy employed by some plants.  Outgrow your predators.  In this case a plant allocates few resources to defense and focuses on growth and/or reproduction.  Balsa trees follow this strategy, they grow astoundingly rapidly and produce copious numbers of seeds.  They are not long lived and have few toxins, as a result they are subject to immense amounts of predation from a wide range of species.  Some of these, such as tapirs, they avoid by growing out of their reach.  Others are more problematic.  I saw a 30 foot tall young balsa tree completely stripped of leaves by leaf cutter ants in less than two days.

Basla saplings - Bolivia

Basla saplings – Bolivia

The most interesting of the plant defenses, to my mind, is animal co-option for defense.  Ants are probably the animal most often co-opted by plants.  We don’t often think of plants as being the ones to manipulate animals, but that is more a reflection of our animal bias than of the true nature of things.  Plants are highly manipulative, in their slow manner.  Like many effective manipulators, they accomplish their ends via bribes (and in a few cases by outright lies – orchids tricking bees into trying to mate with the flowers is a classic example of vegetative duplicity).  Ants are employed as guards by a great number of plant species.

When I first arrived in the Amazon I recall thinking to myself, “Cool, I hope I get to see some of the ant/plant mutualism.”  The first plant I looked at closely was a common understory shrub in the widespread and diverse Melastomataceae family.

Melastomataceae with ant sheltering nodes at the base of the leaves - Peru

Melastomataceae with ant sheltering nodes at the base of the leaves – Peru

At the base of each leaf there was a hollow, swollen node with two small openings on the underside.  Tiny ants occupied these nodes and would rush out to defend the plant when it was bumped.  This is a surprisingly effective defense against herbivores of all sorts, insect and mammalian.  All through the Amazon (and elsewhere in the world) ants and plants have banded together.  I found arboreal ferns with hollow rootballs harboring and colonies, tall cecropia and smoke trees (“palo diablo” – devil trees) with hollow trunks harboring vast numbers of fierce and painful fire ants, and evocative single species plant stands called Chullachaqui gardens.

According to legend the Chullachaqui is a forest guardian spirit that keeps small monoculture garden plots scattered here and there in the forest.  One should be wary entering these areas, ask permission first, and be careful not to damage any of the plants the Chullachaqui grows.  This is good advice as the Chullachaqui gardens are home to a species of ant that lives underground and kills all the plants growing on the surface except for one species.  Animals that interlope are attacked also attacked and the bite and sting of the ant is painful as it contains formic acid.

One of the neatest ant-plant interactions comes in the form of hanging “ant gardens”.

Ant garden in Peru with Monstera spp.

Ant garden in Peru with Monstera spp.

The dense cluster of plants in the above photo is growing from an arboreal ant hive.  Certain plants produce seeds with fatty nodules on them that ants eat.  Ants collect the seeds and store them in their hives, clipping the edible portions off as needed.  Some of the sees sprout and send their roots into the rich material of the ant hive, reinforcing it and protecting it from rain and predators as they grow.  These hanging ant gardens are found throughout the tropics.

Ant-plant interactions are not limited to the tropics.  Some trillium species bribe ants with food to carry their seeds to good growing locations and elderberries in certain portions of North America keep a protective coterie of ants nearby by bribing them with sugar produces from nectaries grown specifically for the ants.

Co-opting an animal may well be the most sophisticated of plant strategies for its subtly, specificity, and efficiency.  Energy cost is at the root of all these strategies.  A plant only has as much energy as it can collect from the sun and soil nutrients.  It must balance its energy use amongst growth, reproduction, and defense.  Every defense a plant employs lessens the amount of energy it can devote to growth and reproduction.  Combining forces with other species can provide a relatively low-cost way for a plant to gain an aggressive, mobile, multi-pronged defense force.  Ants, for example defend their plant hosts with both physically damaging attacks and with chemicals.  That’s a two-for-one defense with an added bonus of rapid deployment for the relatively minimal investment of a home or some food.

Humans may well be mammal plants have trained best.

***

A note about the images and film vs digital in the field:

These photos (with the exception of the hibiscus leaf which is not mine) were taken in 2005 with a well used and abused Canon AE1 with a 50mm 1.4 lens and scanned from the negatives by the developing kiosks in Peru and Bolivia.  The quality of images reflects both the environmental stresses put on the camera and film and the irregular scanning quality.

For long periods of time in the field I still think that film is the better option.  I was in the jungle for months at a time, sometimes in places with no power (20+ days hiking and on a raft in Bolivia for example) and in hot, humid conditions with frequent thundering downpours and rampant mildew growth.  I love the digital camera I use now, but it would have been completely unusable for the majority of the time I spent in South America.

Film cameras do still have their place.

Chert – the birthstone of our species

Few types of stone have as long lasting and intimate relationship with our species as do those of the chert family.  Humans have been using this hard, glassy stone continuously to make tools since the time of Homo habilis, some 1.5-2 million years ago.  Our neolithic ancestors mined chert using fire to crack the stone (see video to see how it was done), at least 33,000 years ago at the Nazlet Khater site in Egypt chert was extracted from subterranean mines,  and flint (a type of chert) was used before we had matches to make fire, today we use crushed chert as the abrasive on some sandpapers, and to extract exquisitely detailed micro-fossils from the distant past.  When I worked as an archaeologist near Santa Barbara most of the projectile points, stone awls, and cutting tools we found were made from chert.

What is this “chert” we have been using so assiduously for the last 2 million years?

Chert is a microcrystalline stone made of silicon dioxide (SiO2) with a cryptocrystalline structure (crystals so fine that they are difficult to see even under a microscope) that lacks cleavage planes.  One of the most useful, for us, aspects of cryptocrystalline materials such as chert is that when they are struck they shatter in a predictable conical manner (conchoidal fracturing).  Obsidian and plate glass share this characteristic, making them and chert excellent for making extremely sharp stone tools.  Chert is more common than obsidian, but still rare enough that it was traded over great distances.  Another beneficial aspect of chert is that it is extremely hard, raking a 7 on the Mohs scale.

A number of well known minerals fall into the chert category: flint, jasper, radiolarite, chalcedony, agate,  and onyx are all types of chert, each with specific characteristics that give them enough difference from each other to warrant specific names.  The famous (and expensive) sharpening stones from Arkansas are made from novaculite, a porous, metamorphosed chert that makes an excellent abrasive.  Flints tend to be high quality cherts that are found specifically in chalk or limestone; these are deposited diagenically (via silicon replacement).  Chalcedony, agate, and onyx are a nested subset of minerals with chalcedony, a fibrous form of chert, being the parent of the group.  Jasper is usually found in association with volcanic activity and is sometimes considered to be under the chalcedony subset.  Jasper, agate, and onyx are popular semi-precious stones used for jewelry and sometimes intricately carved.

Red jasper cameo of Medusa by Benedetto Pistrucci (source)

What got me started thinking about cherts once more was a short day-hike I took with a friend in the Marin Headlands, those steep sided hills to the north of San Francisco that are so often obscured by the thick maritime fog.

Marin Headlands and the Golden Gate bridge partially hidden by fog

Marin Headlands and the Golden Gate bridge partially hidden by fog

The Northern California coast has a complex geology and is undergoing a number of divergent changes simultaneously.  This is an emergent shoreline (Geology of Northern California chapter 10, page 37), a place where the land is slowly rising in elevation.  Rising lands often suffer from high rates of erosion and the California coast has an even more drastic set of factors contributing to the erosion rare than merely rising land.  The bedrock is fractured by many faults, weakening the stone, earthquakes (most extremely minor) shake rubble loose periodically, and both wind and water eat away at the ocean facing slopes.  In addition, the sea level has risen several hundred feet since the last glaciation twelve thousand years ago, and the surf is greedily pounding on the hills, tearing parts of them away.

If you watched the video you probably noticed that the chert they were mining peeled off in plates, indeed that the whole formation was made up of sheets of stone layered atop each other like pastry dough.  About 50% of rock in the Marin Headlands is chert and has a similar texture.

Radiolarin ribbon chert cliff showing soft folds and a sharp fault-line cut

Radiolarite chert cliff showing soft folds and a sharp fault-line cut

This is ribbon chert, more formally known as radiolarite chert.  It gets the latter name because it is a biogenic stone made from the semi-gelled skeletons of radiolaria, a type of plankton that builds a silica based support structure.  These this rock was laid down over a 100 million year span beginning 200 million years ago and is filled with tiny fossils of the radiolaria.  Supposedly some of these are large enough to see with a standard hand-lens.

The folding tells us something interesting.  The folds in the above photo are smooth, meaning that this probably slumped slowly while it was still ductile.  Portions of the cliff have sharp folds where the rock broke, indicating that those deformations most likely happened more rapidly and after the stone had lost much of its ductility.

Red and greenish/blue indicate iron, either in oxodised or reduced form

Red and greenish/blue indicate iron, either in oxidised or reduced form

Much of the chert here is red, but there are many patches of vibrant blue-green and aqua as well.  The colors in chert indicate trace amounts of other minerals.  The red and the lovely greenish-blue are both indicators of iron, the red indicating that the iron has oxidised, the blue-green that it has been reduced (had the oxygen removed from it).  This is similar to the mottled gleying that one sees in wetland clay soils.  I am particularly fond of the blue and green colors in chert, perhaps because they are a bit more rare than the red.

Close-up of blue/green chert bands

Close-up of blue/green chert bands

The hardness of the chert leads to beaches with an interesting texture of sand, more like tiny glossy pebbles than the standard sand.

Chert sand

Chert sand

The combination of colors on the cliffs, beach, sky, and ocean make for a nice combination as well.

Tennessee Valley beach in the Marin Headlands

Tennessee Valley beach in the Marin Headlands

We have been using chert for nearly as long as we have been using tools, close to 2 million years now with no sign of slowing down.  If our species had a birthstone it would probably be chert.

California Condors, Megafauna, and Trophic Cascades

A long time ago I worked as an archaeologist near Santa Barbara.  I spent most of my days in the field excavating Chumash sites, recording evidence of looting, drawing maps, and hunting for unknown sites.  It was a fun job, I learned a lot, and it was my first exposure to California Condors.

The Chumash left behind a repository of exquisite petroglyphs, painted and carved into the soft sandstone that makes up much of the Transverse Range, an east-west oriented set of coastal Southern California mountains.  One of my jobs was to preserve this rock-art.  In the dust that makes up the floor of the caves and shelters the art is painted lives a bacteria that eats the organic pigments in the paint used by the Chumash.  Visitors would unwittingly kick up the dust, spreading the bacteria and speeding up the degradation of the rock art.  At several sites we paved the floor with stones to trap the dust.  One of these sites was Condor Cave in the San Rafael Wilderness; I’m sure you can guess how it came by that name.

Condor art at Condor Cave – from http://www.parks.ca.gov

It wasn’t until several years later I when was backpacking in the Ventana Wilderness with a friend that I saw my first wild California Condor.  We stopped and sat, mesmerized, watching five large birds swoop and soar around us.  Of course my camera was acting up at the time and the only photos I got were pathetic to say the best.  The experience stuck with me, all the more so because I had been studying anthropology and repercussions of the North American megafauna extinctions.  

About a week ago I was driving from San Francisco to Los Angeles along HWY 1.  It was one of those spectacular California days where the coast is shrouded by pockets of thick fog broken by regions of bright sunlight and the Pacific Ocean lives up to its name and lies tranquil in its bed.

Sun, fog, and kelp-beds along the coast between Morro Bay and Big Sur

Sun, fog, and kelp-beds along the coast between Morro Bay and Big Sur

This stretch of road is made up entirely of corners and as I rounded one I saw a pocket of people pulled over in a turn-out looking up at something on the hill-side.   I caught a glimpse of a large bird on the slope, pulled over at the next turn-out, grabbed my camera, and jogged back to find a very calm California Condor sunning itself in the late afternoon light.

California Condor soaking up the last of the sunlight

California Condor (Gymnogyps californianus) soaking up the last of the sunlight

The California Condors are in rough shape.   DDT, hunting by mis-informed ranchers who believe that condors killed calves, egg collecting, habitat loss, and lead-poisoning are all implicated in modern times for the low numbers of  the California Condor (Gymnogyps californianus).   Additionally, these long-lived birds have small clutch sizes (few eggs per breeding cycle) and reproduce extremely slowly; so slowly that a 1996 study by the Fish and Wildlife department found that it would take 1800 years at the current population growth rate of 1.0003 to achieve a stable wild population of 150 individuals.  This low population growth rate is part of why there is a captive breeding program.

California Condor (Gymnogyps californianus) in the Los Padres National Forest

California Condor (Gymnogyps californianus) in the Los Padres National Forest

In historic times the California Condor ranged from British Columbia to Baja, but during the 19th century its range was rapidly diminished to include only California.  Through captive breeding and release strategies the range has been re-expanded and now includes Arizona, northern Mexico, and a little of Utah, in addition to California.  These birds have what is known as a “relict distribution”, that is, they occupy only a fragment of their former range.

California Condor range map - from: IUCN Redlist http://www.iucnredlist.org/

California Condor range map – from: IUCN Redlist http://www.iucnredlist.org/

 

While it is certainly true that lead poisoning, DDT, and all the rest have been massively detrimental to present day condors this overlooks a very important aspect of the condor niche.  These are large birds, the largest flying birds in North America, with up to a 9.5 foot (2.9 me) wingspan and weighing up to 23 pounds (10.4 kg).  These birds are meat eaters and they need a lot of meat.  The historic population was highest along the coast, where aquatic megafauna would, and still does wash up on the beach.  Beached whales, elephant seals, sea lions, dolphins, seals, and large fish may be disturbing to see, but they provide a wealth of food for bears, foxes, coyotes, weasels, wolves, eagles, gulls, ravens, and condors.  It is true that there are still large gatherings of sea mammals along the coast, but it is also true that there are far fewer of them than there used to be and this has imparted an additional stress to the condors, among other species.

Northern Elephant Seals (Mirounga angustirostris) on the California Coast

Northern Elephant Seals (Mirounga angustirostris) on the California Coast

For birds further inland other sources of meat were, and are important.  Terrestrial megafauna is what fed and feeds inland condors.  We have no-where close to the diversity nor the biomass of large free-living terrestrial animals than we did even a few hundred years ago, let alone what we hand when humans first arrived in North America.  Shortly after the arrival of humans most of the large animals, the megafauna (generally being defined as an animal with a body-mass greater than 100 pounds (45 kg) began going extinct.  The giant beavers disappeared, the mastodons vanished, the giant sloths, camel relatives, giant tortoises, horses, and various species of deer were wiped from the continent, and along with those animals also went the animals that relied upon them; dire wolves, saber-toothed cats, short-faced bears, American lions, American cheetah, tetratorns (think condors on steroids), dung beetles, and condors.

Tule Elk (Cervus canadensis ssp. nannodes) being restored to California grasslands

Tule Elk (Cervus canadensis ssp. nannodes) being restored to California grasslands

There is vociferous disagreement as to why the megafauna went extinct, but many, if not most, scholars believe that humans hunted these animals to extinction.  Humans arrived during an ice age and the rapid change in climate (rapid in an evolutionary sense) may have placed the animal populations in a position where enthusiastic hunting had a greater impact than would be otherwise expected; but whatever the exact details the short story is that humans arrived and within a few thousand years a majority of the megafauna went extinct.  This triggered what is known as a “trophic cascade”.

You can think of an ecosystem as being analogous to a game of Jenga.  All together the blocks form a solid tower, but as you remove blocks (species) the tower (ecosystem) becomes more and more unstable.  Eventually one too many blocks is removed and the whole structure comes tumbling down.  In essence, this is what a catastrophic trophic cascade looks like.  So many animals were removed from the ecosystem that now, eleven thousand years later, we are still seeing some of the effects.  Just as blocks you never touched in the Jenga game come tumbling down, species of plants, insects, and animals that were never hunted went extinct or had their life patterns radically altered.  Some plants lost their ability to disperse their seeds, forests and grasslands were no-longer grazed as heavily and the composition of species changed drastically, watersheds and rivers changed their patterns, soils changed as they were walked upon by different animals with different behaviors, concentrations of bacteria and fungus changed, altering soil and groundwater chemistry.  Trophic cascades are a big deal.  They are ongoing, but operate in the background, running smoothly and unnoticed until something breaks the chain of events and the whole tower of blocks comes tumbling down.

The current narrow range of Condors is due, in part to the cascading effects of the megafuna extinctions and more recent changes brought by colonizing Europeans.  We know from the fossil record that prior to the megafauna extinctions several species of condors lived in North America over a range that includes the historic range of the California Condor and stretched across the southern states and up the east coast to New York.

Prehistoric US fossil sites for North American condors, courtesy of the San Diego Zoo library

Seeing the California Condors in the wild is like catching a brief glimpse into the distant past, a time when North America had wildlife diversity to rival that of Africa.  The fate of the condors is far from certain.  They are from a time and place that no-longer exists and it remains to be seen if they can adapt to the world as we have made it, even with our assistance.  I hope the condors do succeed, the world is a richer place and better place for their presence.

Preening in the late afternoon sun

Preening in the late afternoon sun