Saturday, February 26, 2011

Red Sea Expedition: Through Inspiration, Discovery

KAUST is a very unlikely place. A graduate-only science and technology institution with a very international population (faculty, staff, and students), KAUST also has stunning architecture, cutting-edge technology, and world-class research facilities. Situated on the banks of the Red Sea, KAUST is an ideal place to work: in the field in the morning, in the lab in the afternoon and evening, all surrounded with a lively community of students, postdocs, faculty, and visiting scholars.

KAUST placard and inside one of the lab buildings (Photos: R. Rotjan)

The KAUST motto is: "Through Inspiration, Discovery". So, it's my last day at KAUST, and I've certainly been inspired. The labs and facilities are well-equipped, the architecture is stunning. The Red Sea... well.... it speaks for itself.

The stunning Red Sea, and the stunning lab facilities (Photos: R. Rotjan)

Given all of this inspiration, what have we discovered? As you can probably tell from my guest bloggers (here, here and here) this trip, there are TONS of interesting questions to be asked, and much to discover. This is my second trip here, and on my first, Michael Berumen and I documented two new records of corallivory.

2010 "Reef Site" from last years trip to KAUST

On this trip, we've been examining the nutritional basis of corallivory; in other words, trying to find out why fish eat what they eat. Finding out what fish eat has been the subject of many research programs across the globe - the idea being that if we can understand who eats what (or who), we can understand food chains on coral reefs. However, figuring out why fish eat what they eat is a critical next step in understanding how food chains are structured, and understanding how reef organisms will change as reefs change (because food quantity, quality, or availability may be altered with disturbance). We've spent our time in the field collecting tons of samples of food sources, and will also be examining the digestive tracts of various corallivores. After all of that hard work, here is what we have to show for it:

That's right, a bunch of tubes. But don't be disheartened - the contents of these tubes contain answers and discoveries. It will take a few months of chemistry, math, and statistics to finally answer our questions, but that is actually pretty fast. We'll be looking at macromolecular nutritional content - proteins and amino acids, lipids, and carbohydrates. The pursuit of science starts in the field (at least for me), but rarely ends there. All of the post-processing work is critical, so when I get back home to Boston, I'll have quite a lot of samples to work through and keep me busy. :-) But it's not time for me to go home quite yet. Though it's my last day in Saudi, I'm off to Indonesia tonight for a joint expedition with Conservation International, National Geographic, and the New England Aquarium to explore coral seamounts, and to ask new questions. But to help with my transition, I'll keep the KAUST motto in-mind, and leave you with a photo of the Arabian setting sun.

Saudi sunset (Photos: R. Rotjan)

Friday, February 25, 2011

In the Red: balancing the taxonomic books

Though you might think of Saudi Arabia as remote and isolated, KAUST has literally created a scientific oasis in the desert. We have all traveled here from various places (Australia, New Zealand, the UK, Hawaii, and Boston.... to name a few....), but our dispersal across the globe has been for good reason: to come explore the Red Sea and do some new and exciting science. Though I might be geographically isolated at the moment, I have been in good company. In fact, I have been surrounded by a team of stars: Dr. Michael Berumen (my collaborator and host), as well as Dr. Howard Choat (JCU), our previous blog posters, a team of KAUST masters and PhD students, and now Michelle Gaither and Dr. Joseph DiBattista, from the University of Hawaii.

In the last post, Kathryn talked about how fungid corals move surprisingly far. Lizzie talked about how she's going to find out how far fish move within the course of their lifetime. And now, Joey and Michelle are asking about fish movement over evolutionary time - how closely related are different populations of fishes, how does geography influence their populations, and how do unique species form? While we humans are remarkably mobile thanks to air travel, fish movement is a bit more of a mystery. Trying to re-trace history is a tricky task-- especially here in the Red Sea.

Dr. Joseph DiBattista is a postdoc in the Bowen Lab at the University of Hawaii, who is here with HIMB graduate student Michelle Gaither. Joey did his bachelors, masters, and PhD degrees at McGill University in Canada before moving to more tropical climes.

I'll let him tell you his impressions of the Red Sea, firsthand.

Guest Post From Joey DiBattista:

Sniff, sniff ... I love the smell of rotting guts in the morning. The sights and sounds are infectious as the Jeddah fish market gets into full swing. Vendors shouting, the floor slick with a layer of piscivorous slime, colors abound.

Entrance to the Jeddah Fish Market (Photo: J. DiBattista)

Today's visit is a nice break after three days of diving outside of Thuwal in the Red Sea, although that is not to say our time spent on the boat hasn't been fantastic. Our primary goal is to collect small bits of tissue from fish species and invertebrates, for a genetics study, that we might not normally see during regular collections on SCUBA. Deepwater snappers, big groupers, and lobsters come to mind. And it seems that we are in luck, these appear to be abundant at most market stalls, each fisherman pushing his product with a wry grin.

Panulirus versicolor lobsters in the Jeddah Fish Market (Photo: J. DiBattista)

The inability to take pictures due to local customs will make identification of the more obscure fauna a bit difficult, but otherwise this place is a gold mine.

We've actually come down to the Red Sea as part of a large phylogeographic project in hopes of expansion. Indeed, over the past 5 years we have collected samples from reef fish and some invertebrate species at a number of sites in the Indo-Pacific; genetic methods have allowed us to assess the level of connectivity (and dispersal) between islands, archipelagos, and coastlines. Given that our home base is the Hawaii Institute of Marine Biology (not bad at all!!), the survey was initially focused on addressing some interesting historical questions quite close to home.

For example, Hawaii is known for the highest level of endemic (indigenous and exclusive) reef fish fauna in the world, and yet we still don't know where they came from or when they got there. The two competing hypotheses are that reef fish colonized from the west Pacific via an offshoot of the warm water Kuroshio current somewhere near the coast of Japan, or they otherwise made their way up the southern line island chain, perhaps using Johnston Atoll as a stepping stone for colonization into Hawaii. These ideas are based on the overlap of fish fauna between these regions, as well as some models that simulated larval trajectories between such sites. Sequencing DNA at mitochondrial genes (i.e., Cyt b, COI) have allowed us to address theses competing hypotheses by assigning approximate dates to population splitting or colonization events, although the verdict is still out.

The push to get into the Red Sea was spurred by the fact that this body of water is similarly renowned for a high degree of endemic fish fauna (~17% overall). That is, ~17% of the reef fish in the Red Sea are found only in the Red Sea. In fact, endemism is as high as 50% for some charsimatic taxa like the butterflyfishes.

Chaetodon semilarvatus (L) and C. larvatus (R) are both butterflyfish species found ONLY in the Red Sea (Photos: R. Rotjan)

What can explain such isolation? Well, several barriers to dispersal from the Red Sea region have been proposed. First, the narrow (18 km wide) and shallow (100 meters deep) nature of its only connection with the Indian Ocean, the Straight of Bab-el-Mandab, presumably restricts movement of planktonic larvae in and out. This is particularly true during low sea-level stands as recently as 10,000 years ago that decreased the exchange of water masses through this narrow straight and may have led to massive extinction of fish fauna.

Another potential barrier exists just outside of the Red Sea in the Gulf of Aden and Indian Ocean. Indeed, a lack of suitable reef habitat from Somalia to India or Kenya, due in part to the cold water upwelling found off most of this coastline, may greatly restrict the dispersal of reef fish larvae and thus act to reinforce endemic species. Genetic tools provide a means to test these ideas. So, it's now back to the lab to process all of these samples! Balancing the taxonomic books is not simple... but here in the Red Sea, hopefully we'll come out in the black.

Thursday, February 24, 2011

Red Sea Expedition: Acrobatic mushroom corals are fun-guys

It's another day of dissections for me, but Kathryn Furby (from WHOI) is here at KAUST working on some really great corals - Fungia! Corals are animals that typically behave like plants: they don't typically behave too much. Corals are usually colonial, and have many polyps per colony (but not fungids, see below). Each polyp is a mouth (think of each polyp as an anemone -- same idea, and indeed -corals and anemones are closely related). Many corals extend their polyps at night to feed, and keep them retracted during the day. But some corals visibly behave - for example, some soft corals (Xenia and Heteroxenia spp.) definitely showcase the animal side of corals: check out this polyp movement!

But these soft corals aren't the only ones to demonstrate why corals (Class: Anthozoa) are truly "flower animals". Check out one of the most mobile corals on the reef - the lone traveler, Fungia - a solitary polyp on the move. :-)

Guest post from Kathryn Furby, also working at KAUST in Saudi Arabia:

As a coral biologist, I often feel defensive about my level of excitement for an animal that looks like a slimy rock. Corals build islands and protect coastlines from cyclones. Coral creates structures and habitats for fish and other invertebrates to live. There are many important facts circulating in the public and scientific communities about coral reefs, but there aren't enough exciting rumors.

The corals you are most familiar with are stationary, cemented to a network of reef that can extend for miles, like one giant life form. Most tropical reef corals undergo a pelagic larval phase. This means that after spawning, the corals' gametes combine in the water to form free-swimming larvae. This is the only phase of a coral's life where it is able to select its habitat, so you can imagine how important it is.

Once the coral has "settled" on a suitable hard substrate (free of algae and other competitors), it is literally stuck there for the rest of its life. This photo shows baby Stylophora corals that have settled on a larger recently dead Acropora coral.

Meet mushroom corals, family Fungiidae, genus Fungia. These little corals are not the branching Acropora or massive boulder-like Porites coral that you know (and love). Fungia are usually single polyps, and thus are individuals instead of colonies. Fungia mushroom corals consist of a circular disk with one mouth (usually) on the surface.

Exciting rumor #1: The fastest moving coral in the world is the mushroom coral.

This coral has the same free-swimming phase as other corals and also attaches to a suitable hard substrate of its choosing. In this photograph you can see at least three young Fungia corals that are attached. You can see that from the side, young mushroom corals look like their namesake, mushrooms. However, once it reaches a certain size, mushroom corals detach from the reef.

At this point, all bets are off. No longer imprisoned by a base cemented to rock, Fungia corals can continue to move during their youth. Like a student's choice to move away from home for college, maybe backpack through Europe, the mushroom coral continues to move until it reaches a certain size.

How can a coral move?

Figure 1 from Chadwick-Furman and Loya 1992, reproduced with permission from author.

Mushroom corals can be moved passively and move actively. Being a small aerodynamic disk in an ocean environment is tough. You're at the mercy of currents and extreme storms far more than your average sedentary coral. Small mushroom corals often get picked up by current and wave action and moved. Statistically speaking, it's extremely likely that the coral gets dropped upside down. When I first started studying these corals, I got to this point in my research and was boggled by how these animals had survived natural selection. If the coral landed mouth down, it would eventually bleach and starve simultaneously. At the beginning of my fieldwork, I spent a lot of time flipping Fungia back over, saving the world one coral at a time. Or so I thought. As it turns out, Mother Nature is much more clever. Mushroom corals can swell the tissue around their skeleton and actively move. They can also use this mechanism to right themselves after being flipped over. The process is slow, it can take days to complete. If the coral is on sand, it can blow water through its mouth, making a small indentation around it. It is then able to slowly move up the side of the hole until it can flip back over.

Exciting rumor #2: Mushroom corals are also flipping corals.

Mushroom corals are the only corals that can move or be moved onto sand and live happily ever after. As they grow bigger and heavier, they tend to move vertically down the reef, mostly thanks to gravity. As a result many large mushroom corals will end up on the sandy bottom of a reef. When this coral dies, other big sedentary corals are able to colonize their skeletons as a perfect hard substrate.

This photograph shows two dead mushroom corals that are becoming part of the reef. By moving onto sand patches and becoming new reef substrate, mushroom corals are able to create and expand reefs.

In an era of rising sea surface temperatures and ocean acidification, coral reefs need all the help they can get. Fungia are just the super hero corals needed to help expand reef boundaries. They might just become the next charismatic mini-fauna to champion reef preservation. Next time you see a reef in the tropics or in an aquarium, flip out over corals!


Tuesday, February 22, 2011

Red Sea Expedition: How far do fish move?

It is a great pleasure to introduce the first of a series of excellent guest bloggers who I have been working and diving with here at KAUST, in Saudi Arabia. While I am here examining the nutritional basis of corallivory, Lizzie is busily gearing up for an ambitious and important project that will examine the movement of adult reef fishes.

Dr. Lizzie Tyler is a postdoctoral researcher at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia. She is studying the movement of coral reef fish in the Red Sea. She gained her doctoral degree from Oxford University in the UK, where she worked on marine reserves in Zanzibar, East Africa.


From Lizzie:

Marine reserves, areas in the sea which are closed to fishing or other human activities, are becoming an increasingly popular method for conserving the ocean and managing fish stocks. However, to understand how effective they are at protecting different fish, we need to know how far these fish move--or rather swim!

Coral reefs are rich in species, and fascinating to biologists and SCUBA divers, but they also provide important food fish. Here in Saudi Arabia, grouper or hammour is a prized food, especially the Nagil grouper (Plectorhinchus pessuliferus)

A 70 cm long Nagil we caught and successfully released.

In Dr. Michael Berumen’s Coral Reef Ecology lab here at KAUST, we are generally interested in how connected coral reefs are, that is, the extent to which any two reefs share juvenile or adult corals and fish.

If we protect a reef from fishing, we want to know what proportion of time our fish will spend on the protected reef, and whether they are likely to move to other reefs that are still being fished. This movement may be good: providing a supply of fish that have increased inside the protected reef to fishermen on other reefs. This movement may also help to maintain important processes on reefs where fish populations are low. For example, parrotfish are avid grazers, eating algae and dead coral and providing clean rock surfaces for juvenile corals to establish and grow.

Parrotfish in the fish market in Jeddah, Saudi Arabia.

Parrotfish are commonly caught, but are important grazers on coral reefs and if they move between reefs, they can graze on reefs that have been heavily fished, keeping them healthy.

My project focuses on measuring adult reef fish movement. We will be implanting small tags inside the stomach cavity of different fish species. These tags transmit a loud noise, at a very high frequency (above the hearing range of all marine animals).

To listen for these tags, we will place several receivers underwater on different reefs, which will remain stationary. Each tag inside a fish transmits a unique code, which is identified by the receiver. By looking at which receivers have heard which tags, we can map where fish have traveled.

An acoustic receiver being attached to a mooring line.
The receiver will be left there to listen for tags and later removed to download the stored data.

The challenging part of this project is that it requires us to be both fishermen and vets, since we need to capture fish successfully, without harming them, and then perform surgery under anaesthetic to insert the tag before they are released.

Inserting an acoustic tag in the stomach cavity of an emperor fish during surgery.
The fish are kept alive with water pumped over their gills containing anaesthetic.

A small tooth emperor (Lethrinus microdon), just released back on to the reef after surgery
(you can see the stitches on the belly!)

We hope that the results of our project will be used to help design marine reserves both in Saudi Arabia and on other coral reefs around the world. Wish us luck with the fishing!


Sunday, February 20, 2011

Red Sea Expedition: Life on a desert island

Have you ever thought: "what would I bring if stuck on a deserted, desert island?" Being extremely practical, my answer would be loads of freshwater and some form of shade. Or, in earlier years, I might have made a top-10 list of "must-have" books, or music, or something utterly useless on a desert island.

Luckily, I have never been stuck in such a situation, but today I did get to visit Abulat. To celebrate a perfect day with glassy calm seas, beautiful corals, and LOTS of scientific productivity, we ate lunch while anchored by an uninhabited desert island (scorching hot!!!).

Abulat and glassy, flat calm seas (Photos: R. Rotjan)

The island of Abulat is a raised coral island, part of the Farasan Banks off the coast of Al Lith, where we're been working for the past few days. Intriguingly, it has an emerged coral knoll, which basically means that there are old (probably fossil) corals exposed above land. If you look at the below photo, you'll see two pillars in the center. If you look closely, you might notice the radial polyps characteristic of Acropora corals.

(Photos: R. Rotjan)

These emerged coral knolls contain lots of information about what used to live in the sea. I'm not a paleobiologist or a geologist, so unfortunately I have no idea how old these islands are, but you can see an exposed bivalve shell and many other mollusks and corals exposed in the rock that are still living on Red Sea reefs today. These sorts of exposed coral outcrops are commonly used by paleobiologists and geologists to understand how reefs used to look, and to understand how past disturbances have impacted reefs. Because corals and other reef organisms are made of calcium carbonate, they leave their stories behind in the rock. In special places like Abulat, those stories are exposed for all to see (no digging required).

Photos: R. Rotjan

A quick online search revealed the following Springer Image from a book by Eric Bird called Encyclopedia of the World's Coastal Landforms. You can see from the diagram below how geologists characterize different landscape forms:

Image provided by Springer


Fig 1
Abulat Island, a raised coral island on Farsan Bank, Saudi Arabia. 1 – low coast, 2 – coast with fallen blocks, 3 – overhanging scarp, 4 – double overhang, 5 – successive overhangs, 6 – beach rock, 7 – living coral heads, 8 – fault scarp, 9 – low plain, 10 – karstic plateau, 11 – heights in metres, 12 – emerged coral knoll.

For those of you who demand live organisms in every post, here's a bonus. :-) After exploring Abulat, we spent a few minutes watching the schooling fish that swarmed around us. Unlike me, they really do spend their life by a desert island:

Photo: R. Rotjan

Now, if you look closely, you'll see that there are three different schools of fish interacting with each other, all being threatened by larger fishes below (jacks and snappers). The sandy bottom makes it easy to see all 3 fish schools.

At any rate, am tired and happy after another day of hard work in the Arabian sun, but (thankfully not stranded), am back onshore. As for that top-10 list... maybe I should bring a geology book next time. :-)


Friday, February 18, 2011

Red Sea Expedition: A remarkable chain of events

After a brief trip to freezing-cold Boston (brrrr), I'm now in Saudi Arabia, once again examining fish-coral interactions and continuing the work we started last year. I am once again grateful to be hosted by my colleague Dr. Michael Berumen, an Assistant Professor of Marine Science at KAUST, the King Abdullah University of Science and Technology.

A photo from today's dive in the Red Sea (Photo: R. Rotjan)

On my way here, I flew over Egypt, of course all-the-while wishing my friends and colleagues in Egypt a smooth and safe transition in this tumultuous time, following the recent chain of events. You'd never know from the air that anything had changed, though. I flew over Luxor (the ancient city of Thebes) at sunset, and then over the Nile, and then Valley of the Kings. Looking down at the desert with the setting sun was stunning (sorry no photos - couldn't get my camera fast enough), and I was struck at the beauty of desert mountain chains.

Now, 2 days, 5 dives, and less than 10 hours of sleep later, I am once again struck by the beauty of chains - but not mountains this time. Today's dives were full of research-related activity, but we all spent a moment or two admiring the chains of salps that were visiting the reef.

(L) A long chain of salps, curling as it gets caught in the reef; (R) Many salp chains floating above (Photos: R. Rotjan)

Salps are pretty interesting creatures. They look like jellyfish, but guess again! They are actually more closely related to vertebrates (they are in the Phylum: Chordata). They are relatively rare on reefs; the only other time I've seen them is blue water diving with Dr. Larry Madin (Woods Hole Oceanographic Institution) in the Phoenix Islands. The reason salps are so rare is because they are typically open ocean, pelagic animals. They slowly swim through open water, all-the-while filtering the water for food. Every once in a while, they get swept onto the reef from offshore. We were diving on very dramatic reefs with slopes that literally rise from the depths without much by way of ledges or shelves--just a steep wall of coral, and then an open vista of blue.

Reef wall to the left; open water to the right; salp chain getting blown in from the blue to the reef. (Photo: R. Rotjan)

Salps don't always form chains; they can also live as solitary individuals. But an individual can reproduce asexually by making clones, which form a chain. The chains start out small, both in size and number, but 10's-100's of clones can form, all tiny at first. The chains can stay together for a long time, swimming and feeding on plankton together until they eventually break apart from each other.

Chains can curl, bend, or be straight, but are always beautiful. (Photos: R. Rotjan)

They are important organisms that filter phytoplankton in open oceans. They are difficult to study, but Dr. Larry Madin is an expert (see his posts from the Phoenix Islands Expedition here).

A salp chain close up from bellow, looking up. Clouds are visible above. (Photo: R. Rotjan)

For me, salps are an important reminder that reefs are connected to the sea around them. It's tempting to think of a coral reef as an oasis in the middle of an open-ocean desert (especially in Saudi Arabia!), but the open ocean is full of life which interacts with reefs. For example, when salps get swept onto a reef, they also become food for many fishes. We observed tons of feeding behavior as tons of reef fish ventured out of their comfort zones to nibble on a small salp-snack. Nutrients in the open ocean also arrive on reefs from offshore and from deeper currents. Pelagic filter-feeders like salps also help to keep waters clean and clear (which is critically important for tropical reefs).

Red sea reef with crystal-clear water (Photo: R. Rotjan)

Typically, when I'm on a reef wall, my attention is wholly focused on the corals and my back is to the blue. But today, I had a great reason to turn around and admire the salps and remember the critically important role of the organisms in the surrounding sea.

More soon,


Thursday, February 10, 2011

Panama Expedition: Up close and personal

Hola! Things here in Bocas del Toro are going well. We have had many fish-related successes in the lab and the field. One of our more exploratory endeavors was to set out a light trap and do a plankton tow in the hopes of glimpsing some larval fish.

Three Seas Program students Jennifer and Maggie, along with their instructor (Randi) doing a night-time plankton tow to catch fish larvae. (Photos: Christopher Marks)

Most reef fish species reproduce by releasing eggs, which get externally fertilized and then drift through the plankton for days to weeks as larvae before settling on a reef. Getting a glimpse of newly hatched larval fish is a special treat. Usually, they are several days into their larval duration by the time we see them. Check out these little tiny fishes, glimpsed under the scope...

Heidi Block, our teaching assistant, found a fully grown arrow blenny that was tiny enough to necessitate some microscope investigation. Yes, this is a fully grown, reproductive adult capable of producing eggs and larvae of its own:

Lucayablennius zingaro, the arrow blenny

I could go on and on, but you're better off hearing it from an expert who works on larval fishes: Heidi Block from California State University, Northridge.

Heidi writes: Larval fish are incredibly small, often transparent and float around in large bodies of water; this makes them very difficult to study. One way to deal with this is to look at otoliths. Otoliths are calcium carbonate structures found in the ears of fish. Their function is to detect both sound and gravity however they also provide a history of an individual. They do this by the formation of daily rings, much like how trees form rings. Many species also have a settlement mark, which is a mark on the otolith formed when an individual leaves the plankton and joins a reef. Using the settlement mark and daily ring formation you can determine larval characteristics without having to deal with the difficulties related to working with larvae. By counting from the core of the otolith to the settlement mark you can determine the age at which a fish is settling on a reef, you can also determine growth rates during the larval stage by looking at the width of the daily rings, and in addition you can determine the size at which an individual settled onto the reef. Determining what is happening in the larval stage and how this influences individuals once they settle on the reef is an important step in understanding the population dynamics of reef fishes.

This is an otolith from a temperate wrasse, Oxyjulis californica. The black line indicates the area on the otolith associated with the planktonic phase of this individual. The red line is the settlement mark and the blue line is the area associated with the time this individual spent on the reef.

Randi writes:
This is the last night of the course, so we're going to sign off and head home. The students are off to take their next course (Terrestrial Tropical Ecology), but we (Liz, Clare, Heidi and I) are headed home. We hope you've learned more about the Panama reefs, and fish in general, from this Expedition. Thanks for reading!!

Randi, Liz, Clare and Heidi