Sunday, 27 July 2014

Taking stock and taking off for home


St. Croix sunset.










Knowing we were about to leave St. Croix (and the Caribbean), we had an intense sprint to finish all of our research.  In our last month we conducted our standard coral reef and fish assessment surveys, measured grazing visually, with small “GoPro” video cameras and with bits of seagrass that we measured being munched.  We studied patch reefs, fore reefs and along depth gradients.  We quantified reef components around all of my long-term study areas and measured light intensities in the water in front of all of our study sites. 

Chancey lowers light sensor from the Zodiac, Doug reads the integrated light measurements on Alaria.

Our research team turned over during this final month.  We began our research in St. Croix with Dr. Peter Mumby and Ms. Natalia Rincon-Diaz joining Chancey Macdonald and me, when they left they were replaced by Dr. Doug Rasher (reef ecologists who focuses on plant-herbivore interactions) and David Conover who heads Compass Light Productions specializing on video documentaries about marine conservation.

St. Croix science team (Peter Mumby, Bob Steneck, Chancey Macdonald, Natalia Rincon Diaz - right to left).
Last team including David Conover and Doug Rasher (left and 3rd from left).
The waves of new people kicked us into high gear with some of our dive teams having as many as eight dives in a day (all shallow).  After they all departed and it was time to prepare Alaria for the long sail home.  I removed all of the research gear including donating the very functional compressor to the East End Marine Park who desperately needed one.  All of the sailing and cruising equipment had to be inspected and readied for our passage.
Jose Sanchez accepts our compressor as a donation to the St. Croix East End Marine Park. 

















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TAKING STOCK: WHAT DID WE LEARN?

I set out to study the coral reefs of the eastern Caribbean because they represented a conspicuously understudied region in the Caribbean.  By focusing primarily on low islands, I hoped to minimize pollution and sedimentation effects attributable to runoff.  Since these eastern most islands will not likely have significant upstream pollution.  It is equally unlikely that adjacent islands affect would one another because of the strong equatorial current running between isolates virtually each island.  We assume that climate and atmospheric effects such as ocean warming or acidification would affect reefs equally.  What we wanted to determine was whether reefs displayed different conditions of “health” and if so, what conditions most contribute to healthier coral reefs?

All study sites, number of transects and quantity of data generated throughout the eastern Caribbean.
We studied coral reefs on 15 islands along the eastern Caribbean archipelago over an 8-month period.  Live coral cover averaged about 20 percent ranging from 0 to 66%.  Some of the sites with higher coral cover were protected from fishing but that pattern is not necessarily cause and effect since sites with higher coral cover could have been selected for protection (e.g. Soufriere Marine Management Area in St. Lucia).  It is clear that seaweed is bad for coral reefs.  Where seaweed was abundant, adult and juvenile corals abundance were less abundant.  Harmful seaweed was usually less abundant where Diadema sea urchins and/or herbivorous fish such as parrotfish and tangs were abundant.  In this case, the relationship IS likely cause and effect.  The herbivores that eat algae keep the coral reefs relatively algae-free.  We found the conditions ascribed to “healthy” coral reefs most commonly found on coral reefs with relatively little fishing pressure.
Seaweed covered reef with little live coral and poor habitat architecture.
Reef with little seaweed, abundant coral, herbivorous tangs and considerable habitat for fish and other reef-dwellers.

The sea urchin, Diadema, does well in fished areas.  This may be because fish that eat it are heavily fished in many areas of the Caribbean.  So reefs with sea urchins and considerable fishing can do well as can reefs that are not fished at all but have large and abundant parrotfish.  Trouble is that most reefs fall between those two extremes.
Reef well grazed by Diadema sea urchins (very little seaweed).

Possibly more interesting than the critters we found were the critters we didn’t find (or rarely found) on this odyssey.  Specifically, almost all large bodied fish were absent from most coral reefs.  We saw only a few large groupers and sharks.  Several large predatory fish that were common 40 years ago such as barracuda and some groupers are largely absent now.   Non-native (invasive) lionfish were surprisingly rare at most of our sites. We only saw a few during the entire project.

There is still much to do.  We have mountains of data to analyze on reef corals, seaweed, patch reefs, fish and sea urchin fauna as well as time trends for all of these factors for some sites .   David Conover is working on the footage he took to see what sort of public vehicle might be best for getting the word out.

Doug Rasher and David Conover work in Alaria on their data and video documentary, respectively.

Nevertheless, we can make some conclusions about the coral reefs of the eastern Caribbean.  Obviously, they have degraded over recent decades.  There is less live coral, fewer fish and water clarity has declined.  However, we also see seeds of hope in the abundant elkhorn coral that is springing up around St. Croix and elsewhere.

Relatively healthy elkhorn coral reef in St. Croix's Buck Island National Monument.
One of our last Caribbean sunsets before departing.
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SHOVING OFF FOR MAINE

Our long-haul crew for the trip home included Dr. Ansley Sawyer (life long sailor and “Mr. Fixit”) who sailed with me on the way down, Dr. Lew Incze (oceanographer and professor at the University of Maine who’s summer job during college was to deliver sailboats from New York to Maine), Mr. Ed James who sails from Chesapeake Bay and has myriad long-haul cruises under his belt.

The "long-haul" sailors, Lew Incze, Ansley Sawyer, Ed James and me (right to left).                                                                  
After readying the boat, stocking it with food, fuel and water, we cleared customs and departed for parts north.
Departing the Caribbean.
Where to go?

If you draw a straight line from St. Croix to Maine it nearly goes through Bermuda, which is a bit over 900 miles away.  However, we were watching the weather and storm after storm swept over North America, and out to sea north of Bermuda.  Those storms are NOT something to mess with… they can be intense and we are a small boat.  We thought we could get to Bermuda easily enough but we weren’t sure we’d find the weather window we need to leave from there to Maine.  In fact we realized that we could be pinned down in Bermuda for weeks and none of us were excited about that possibility.  So, we set sail for Norfolk Virginia.  It would be over a 1300-mile run that would take us 13 days but once there, we’d have lots of options for working our way up the coast dodging storms along the way.
Our cruise track back to Maine (a circle marks noon of each day of our journey to Norfolk Va.)


Alaria holds 30 gallons of diesel fuel and we had an additional 20 gallons in carboys lashed to the rails.  This would give us about 4 days of motoring time – so clearly we had to sail most of the way.  We also were mindful of our water capacity.  We hold 70 gallons of freshwater in two 35-gallon tanks that we use sequentially.  We also have a 6-gallon “emergency” supply of freshwater lashed to the rail.  I’ve learned over the last 7 months that if we conserve, four people use about 5 gallons per day so we would have about 14 days of water for a journey that took us 13 days to complete.  Actually, we had a bit of luck regarding water.  On day 6 of our cruise we were hit with a downpour that allowed us to wash our deck and plug the drains (called “scuppers”) so water accumulated over the fill cap for water tank #2 (the one near the cockpit).  When I opened the water tank cap, water cascaded into the tank and in about 2 minutes the tank was full.  We had another 14-day supply, which we knew would be more than enough for this passage.

Lew flying our spinnaker.

During our long crossing, we had generally good weather except for a storm that packed winds over 40 knots.  This gale rattled the boat and rigging despite having two reefs in the main sail (making the sail shorter) and we were sailing only with the tiny staysail before the mast.  After a while we decided to “heave to” which amounts to setting the sails so the boat stalls where it is heading into the waves so we just go up and down under remarkably stable conditions.  We call that “parking the boat”….  Once done, we all went down below and rode it out until the winds were down to a manageable level.  We had very big seas and the wind was blowing the tops off the waves but I didn’t think to take a photo of that fury.

We arrived in Norfolk early on Saturday 10 May.  We went straight to a marina where we could take showers, buy provisions and get a few meals in restaurants.  After a solid day of cleaning and shopping we were ready to go and the weather looked good for an early Sunday departure for points north.

The weather remained unstable so we made passages close to shore and took the New York City – East River run to Long Island so we wouldn’t be trapped outside with no harbors of refuge.  We were now coastal-cruising…  so we could drop an anchor and wait out bad weather rather than struggling against it. 

Approaching New York City.

The new World Trade Center (left) and Brooklyn Bridge (right).

After waiting out a 20 knot blow that would put wind on our ‘nose’ heading down Long Island Sound, we began our final push to home.  We motor sailed directly to Onset Massachusetts where took on our last load of fuel and water while waiting waited for a favorable tide to push us through the Cape Cod Canal.  Along the way, we noticed that the main sail had developed a small tear along its outer edge.  Fortunately, the wind was now at our back so we sailed across the Gulf of Maine with only our Yankee fore sail pulling us home. 

Finally, all of the islands of Midcoast Maine such as Damariscove, Fishermen, and Outer Heron came into clear sight.  These are the islands I’ve worked around studying lobsters and sailed around on various boats over the past three plus decades. 

Sailing past Maine's Damariscove Island heading to South Bristol.

We motored through The Gut in South Bristol to Bittersweet Boatyard where our wives had assembled to greet us.  It was a terrific homecoming.  Maine’s verdant Spring looked wonderful.  It wasn't tropical at all.  It was home!

Alaria back at our point of departure on our mooring in South Bristol, Maine

Wednesday, 23 April 2014

Life, Death and Rebirth of a Coral Reef: Witnessing ecosystem change over the past 42 years




1972 St. Croix -- I'm getting ready to dive into a career in marine science (but with a clipboard and a spear?)
























HEADING NORTH TO ST. CROIX

At first light on March 18th we departed the Grenadines for St. Croix.  It’s a 370 nautical mile run that took most of three days.  The first 24 hours we had 20-knot winds on our beam and we sailed over 7 knots the entire time…. Terrific!

Approaching St. Croix from the south.
St. Croix and its coral reefs.  Our focus was on the reefs around Buck Island and on St. Croix's northeast shore.
Logistics dictated that St. Croix (U.S. Virgin Islands) would be the last research site of the Antilles Expedition.  Ironically, it happened to also be the place where I was first introduced to coral reefs as an undergraduate student in 1972.

Students at West Indies Laboratory 1972 - I'm reclining shirtlessly

THE WAY THINGS WERE….
A BRIEF HISTORY OF ST. CROIX’S REEFS OVER THE PAST 10,000 YEARS

The coral reefs surrounding the east half of St. Croix including Buck Island are among the best developed of the eastern Caribbean.  The Tague Bay Reef along the northeast shore reef runs nearly 6 kilometers without a break.  It is also one of the best-studied coral reefs in the Caribbean.  My first job after I graduated from college in 1973 was to assist Dr. Walter Adey of the Smithsonian Institution in drilling through St. Croix’s coral reefs and algal ridges to determine how thick they are and how long they took to develop that thickness.  What we learned was that these reefs are 30’ (10 m) thick and they developed mostly over the past 7,000 to 10,000 years.  Reefs were mostly built by the remarkably large branching elkhorn coral (Acropora palmata).  So, this is a wonderful site to study because we know it was a great place for coral reefs to grow for millennia (the same cannot be said for some of the rocky reefs we studied in places like St. Maarten and St. Lucia).
Studying the algal ridges at Isaacs Bay 1973
For younger reef scientists, it is hard to imagine the structure of coral reefs of the 1970s.  The shallow reefs were an expansive tangle of complexly branched elkhorn coral that went on for miles and miles.  The reef fish used the branching habitat for the food and myriad “hidey holes” it provided.

Buck Island elkhorn coral reef in 1973. In the center of the photo lurks a large barracuda
On a few occasions I would get my Nikonos I camera with only enough film to take 36 black and white photos of the coral reef.  I would often photograph large predators such as barracuda, groupers and large snappers. 
Tiger grouper on Tague Bay reef 1973
Everything made sense.  I was taught as a student that highly complex ecosystems such as coral reefs were highly stable.  Scientists of the 1970s published articles speculating that the only thing that could change this coral-dominated state would be another Ice Age over the next 10,000 years.  This was the widely held consensus among most coral reef scientists at the time.  As the famous coral reef scientist, Jeremy Jackson, has frequently pointed out – most of the world’s best coral reef scientists were using the best scientific methods available at the time but none predicted the widespread collapse that we have observed in recent decades.

Speaking for myself, I was studying the St. Croix’s coral reefs for my PhD dissertation (with Jeremy Jackson as my advisor).  I set up experiments on the Tague Bay fore reef in 1979 and continued to follow the dynamics of change there until 1995 (so this included period after I was hired by the University of Maine in 1982).  Over that short period of a decade, I saw the coral reefs of St. Croix collapse into an unrecognizable wasteland.

My 2 and 5 meter sites on Tague Bay forereef collapsed from 1980 to 1990
The 1980s was the disastrous decade for Caribbean coral reefs.  Two diseases hit about the same time but the rate of their impacts were very different.  Chronologically, the first disease was the White Band disease that infected the elkhorn and staghorn corals beginning in the late 1970s.  It was easy to spot.  It attacked the elkhorn and staghorn corals at the base and progressed slowly upward.  The lethal white band spread considerably faster than these corals can grow.  It created a wave of death visible from low flying airplanes. Bill Gladfelter, a scientist working at St. Croix’s West Indies Lab, published a paper in 1982 showing the elkhorn coral mortality and suggesting that if this disease continued, it could eliminate the dominant coral of Caribbean reefs.  His paper was largely ignored until late in the 1990s when it dawned on reef scientists that he was right.  The elkhorn and staghorn corals had died throughout most of the Caribbean.
The black-spined sea urchin Diadema and its well grazed reef.
The second disease attacked the black-spined sea urchin “Diadema” (Diadema antillarum).  This sea urchin had attained remarkable population densities throughout the Caribbean.  In St. Croix on the Tague Bay reef I was studying, we documented over 17 per square meter at my 15’ (5m) site.   So, imagine your desk is about 3’ by 3’ or one square meter.  Now imagine that desk with over 17 large sea urchins with long spines packed with poison.  Until 1983 these were the bane of most coral reef scientist’s existence.  Most scientists and tourists at the time had close encounters of the most unfortunate kind.  Although these urchins hurt, scientists such as Bob Carpenter, Paul Sammarco and John Ogden were conducting experiments to see how they functioned in coral reefs.   All the studies pointed out that Diadema keeps coral reefs and the surrounding areas ‘mowed’ down so no seaweed was present on most Diadema dominated coral reefs.  Studies of experimental removal of all the Diadema showed a very rapid shift to harmful seaweed.

My experiment (coral settlement plates) at 5 m in 1980 with Diadema nestled around the base of the corals.
Suddenly everything changed.  Starting in 1983 and progressing to 1984, Diadema suffered a mass mortality from a disease.  The disease began in Panama so speculation is high that a pathogen from the eastern Pacific caused this outbreak but to this date we simply do not know how the disease started or where it came from.  Nevertheless, what we do know is that the early experiments showing how important this sea urchin is as an herbivore was absolutely correct.  Within a month of the sea urchin disease outbreak, coral reefs throughout the Caribbean were overgrown by seaweeds.  The earlier sea urchin removal experiments were spot-on.  This was an important grazer that kept the coral reefs of the 1970s healthy and free of seaweed.

Because Diadema was so abundant and when the disease hit a reef all of the urchins died in a day or two, there was no mistake that a serious epidemic had struck the Caribbean coral reefs.   The slowly creeping White Band Disease (WBD) was often conflated with the effect of the Diadema mass-mortality (I published a paper in 1994 pointing out the impact of herbivore loss without mentioning that the coral decline was likely from WBD).

The combined effects of herbivore loss and increase in area where seaweed can grow (due to WBD of the dominant coral) effectively diluted the grazing pressure from the remaining herbivorous reef fish such as parrotfish.  With such low levels of herbivory the coral reef “flipped” into becoming a seaweed reef.

By the end of the 1980s none of the reef scientists were saying complex and diverse coral reefs were stable.  What we had all witnessed was one of the World’s most rapid and widespread collapse of a complex ecosystems.

THE DEATH SPIRAL OF CORAL REEFS LOCKED INTO SEAWEED REEF STATE

As I’ve been studying reefs of the eastern Caribbean, I’ve come to recognize the alternative state of coral reefs is one dominated by seaweed.  It is an alternative state from which it is difficult to recover.   Based on all of my surveys at 30’ (10m) depth from this expedition, the abundance of seaweed still exceeds the abundance of coral.  Arguably, these should no longer be called “coral reefs” and since it has been 30 years since coral-dominated reefs became seaweed-dominated reefs, this could now be considered an “alternative stable state”.

Returning to St. Croix for perhaps the last time in my professional career had me thinking that this was going to be just another example of a fully collapsed coral reef ecosystem.  The only reason it was worth studying is that I was revisiting the exact same reef sites using the same methods over the decades before, during and after reef collapse.

REBIRTH OF A CORAL REEF

We revisited the exact area of the Tague Bay reef where I conducted my PhD research starting in 1978.  That was before we had “global positioning systems” (GPS) so I had used distinct houses on the shore to line up my study sites.  Remarkably, they were still there so I was on my old study site!

Swimming up the reef from 30’ depth, the reef hadn’t changed much but then I started to see Diadema and coral.  At 5 and 2 m (15 and 6’) it was clear that the grazing Diadema were back, seaweed was relatively rare, coral was more abundant (so were the baby corals).  To me, it seemed I was witnessing a rebirth of a coral reef.

Trends in abundance of corals, diadema and seaweed from 1980 to 2014 at 2, 5 and 10 m (6, 15 and 30 feet).  Note that the trends are positive at shallow two depths.
Make no mistake, the reef had a long way to go.  While there was some elkhorn coral scattered about, it was nothing like the elkhorn that was here in 1980.  But all of the shallow water trends were positive!

Tague Bay forereef at 5 m (15')  1980.
Tague Bay forereef at 5 m 2014 (same site as the photo above from 1980)

Nevertheless, seeing large proud elkhorn coral at my 2 m site and also seeing lots of baby elkhorn coral indicated to me that the real reef builder could be coming back

Tague Bay forereef at 2 m 1980 - 1988.  No elkhorn coral was alive in 1988.

Tague Bay forereef at 2 m 2014 (same place as above) with numerous live elkhorn coral!
We then travelled to Buck Island National Monument.  This is now a no-take reserve where fishing is illegal (they started enforcing the no-take regulation around 2003).  While some of the coral I had seen in 2003 had died, in the shallow zone, was the most extensive stand of elkhorn coral I’ve seen in the last 30 years.

An elkhorn coral reef on the southern bank barrier reef on St. Croix's Buck Island.   This is the densest stand of elkhorn coral that I've seen anywhere in the Caribbean in over 30 years!

Elkhorn coral is among the fastest growing corals in the Caribbean.  At this Buck Island site, I had placed coral settlement plates for Park scientists to study but that hadn’t happened.  So, the plates were still there.  It was a great opportunity for me to see what had happened to them in the past 12 years.  Some large corals had overgrown the settlement plates.  Baby corals that had attached to them were now adult corals.   It is amazing what you can learn from accidentally leaving an experiment for more than a decade!

Terracotta coral settlement plates I deployed in 2002 (left) and how corals have grown on and over them in the past 12 years

 However, the biggest surprise was coming upon a plate that was completely enveloped by the base of an elkhorn coral.  The coral had grown 60 cm and and across 1 m (24”, 39”, respectively).  That’s an impressive amount of growth.  As I looked around and saw how many baby elkhorn coral I could see, I thought I was in fact seeing the rebirth of a coral reef!

Elhorn coral growing over a terracotta settlement plate (plate is 10 cm or 4").

Elkhorn coral that grew up and over a coral settlement plate (coral is 60 cm high and 100 cm wide or 24" and 39")

THE RETURN OF THE KING!  ..... maybe?

The biggest source of despair among Caribbean coral reef scientists has been the loss of elkhorn coral because it has produced far more coral reef rock than all other species of coral combined.  It grows fastest, it has the capacity to produce coral reefs best able to keep up with rapidly rising sealevel (which is predicted to occur in the next century).  So, the ample evidence that elkhorn corals are proliferating here in St. Croix is great news and offers renewed optimism for the future of Caribbean coral reefs.



I sure hope an assessment of these coral reefs 40 years from now is as positive as this entry.



Sunday, 23 March 2014

Coral reef oases in the eastern Caribbean

Alaria at Tobago Cays Marine Park
Coral reef at Tobago Cays Marine Park

After Mustique, we sailed south to the drop-dead gorgeous Tobago Cays Marine Park (“TCMP”).  There, the Park Rangers took us to reefs they have been monitoring for some time. We spent a week there before we sailed on to Union Island from which we traveled to Petite St. Vincent again courtesy of the TCMP Rangers and their fast boats.  Finally, we sailed to Carriacou in the country of Grenada.  This was our most southern station where we surveyed the island’s reefs along its windward east coast and south coast.  So after over 170 coral transects and nearly 500 fish transects we had surveyed most of the coral reefs we had targeted in the eastern Caribbean.  Now, we can consider what, if any, patterns we’ve found.

The Grenadines with the most extensive coral reefs (right inset)
Fig. of eastern Caribbean Islands including Grenadines

A “SNAPSHOT” OF THE EASTERN CARIBBEAN CORAL REEFS

Living coral comprised less than 20% of the hard surfaces we surveyed from Anguilla to Carriacou.  This is a low number but it is comparable with most coral reefs of the Caribbean today.  Nevertheless, three regions -- St. Lucia, Mustique and Tobago Cays -- had higher than average coral cover and a higher than average abundance of baby corals.   Similarly, two of those three regions had lower than average abundance of harmful seaweed.  Grazing fish such as parrotfish and surgeonfish were most abundant at Mustique but they were either average of above average at those three regions.  The most prized reef fishes to eat are groupers and they were most abundant at both Mustique and Tobago Cays.

The relatively healthy reef at Mustique
Relatively healthy reef at Tobago Cays Marine Park
In short, it appears that all of the reefs with better than average conditions for coral reef health (abundant coral, baby corals, little seaweed, many and grazers and relatively abundant predators) were all found in no fishing “marine reserves” with effective enforcement.  In the larger view this included St. Maarten, St. Lucia (Soufriere Marine Management Area), Mustique and Tobago Cays Marine Park.

Average coral, seaweed and baby coral abundance.  The blue horizontal line represents the Antilles average.  Note that St. Maarten, St. Lucia, Mustique and Tabago Cays have enforced marine protected areas.

There are, of course caveats to the pattern that reefs with less fishing are “healthier”.  For example, it is possible that areas with high coral cover were targeted for protection.  That certainly happened in St. Lucia and possibly Tobago Cays Marine Park.  However, Mustique’s protection was established with little specific knowledge of what coral reefs existed there.

Specific reefs within managed sites vary greatly.  Sometimes this is due to natural variability found in any ecosystem.  However, in some places we think we see some patterns that may have caused the local variations.  To address why adjacent reefs differ, we targeted a few sites for more detailed studies with some more expertise.

OUR RESEARCH TEAM GROWS!

For help on why reef fishes and seaweed abundances vary so much among local coral reefs Dr. Peter Mumby (University of Queensland) and Ms. Natalia Rincón Díaz (Universidad Nacional de Colombia) joined our team.  Both of these scientists will spend a month working on these problems from Alaria. 

Dr. Pete Mumby (reef fish ecologist) sailing to our study site on Alaria.

Natalia Rincon Diaz (a seaweed expert) joins our group.
In the way of introductions, Dr. Peter Mumby is an Australia Research Council, Laureate Fellow and heads the University of Queensland’s Marine Spatial Ecology Lab.  He is the President of the Australian Coral Reef Society but most of his research over the past few decades has been on coral reefs of the Caribbean.  He is one of the world’s leading experts on the ecology of coral reef fishes (Google him if you are curious).   Natalia is a masters student at her university who is studying the relationship between herbivorous fishes and the algae they eat.  I saw this a great opportunity to help advance her career while helping us with our studies.  She will have full access to all of our data to help her in her masters thesis research.

Science discussions intensify during our sunset chats.
WHY ARE SOME CORAL REEFS SO DIFFERENT FROM OTHERS NEARBY?

While it is great that there are areas with higher than average coral cover and fish abundance, it is also interesting to consider why another reef nearby is different.  We suspect there are two big factors affecting reefs.  One is one is the variability of reef structure (that is, its habitat architecture), the other is how fishing pressure changes from place to place.  These are by no means the only factors causing the variability we observed but we think they may be factors contributing to the differences.

Corals create the architecture of reefs.  This includes those corals alive today and the skeletons of corals past.  This architecture may take centuries to develop but it provides places for fish and other critters to live or to hide.  The habitat architecture of reefs increases the surface area on which seaweed can grow and herbivores such as parrotfish can graze.  So, we wondered if differences in habitat architecture may explain the differences we see among adjacent and nearby coral reefs.

A simple and relatively featureless reef in Barbuda.
A complex elkhorn coral reef at Tobago Cays Marine Park.
To examine these questions in greater depth we set out to measure habitat architecture by measuring the length of coral structure under each meter along a 10 meter transect.  With our measurements we learn how high and how dense the coral structures thrust into the overlying water.  We get a sense of how much reef surface area there is in any given space.

Bob measuring spatial complexity of the coral reef (photo Pete Mumby).

We also measure how the topography of the reef is being used by grazing fishes.  We watch for 5 minute periods and via small video cameras, the bite rates on the reef by parrotfishes and tangs.   As the surface area of reefs increase, so to does the area on which seaweed can grow. So it may be necessary in high complexity areas for more parrotfishes grazing just to keep the reef clean of harmful seaweed.

Natalia quantifying the rate at which herbivorous parrotfish and tangs bite tops, sides and bottoms of complex reef surfaces.
Because it is also possible that fish behave differently on these reefs, Peter Mumby documented the grazing behavior of the dominant parrotfish including juveniles and adults.  We also deploy video cameras to film fish grazing at sites that range from high to low complexity

Pete quantifying bite rates for different size and species of grazing parrotfish.
One of several compact GoPro video cameras quantifying fish grazing without a human presence.
We will need to considerable analyses beyond what I’ve presented here.  However, we are beginning to see patterns that make sense.  This is also information that reef managers will want to know.  In a future blog I’ll describe how we have been meeting with managers at each of the islands we are studying.  All of them are eager to hear what we have learned.

The beauty of coral reefs today.  All these photos happen to be from reef protected areas.

Elhorn coral in TCMP

Neon gobies on a star coral.
Sponges in the Soufriere Marine Management Area

A green moray in Mustique's Lagoon reef.