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


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.


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.

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.

Wednesday, 19 February 2014

The Grenadine archipelago: Bequia and Mustique a study of contrasts

Alaria sailing to Bequia
Rain squalls over St. Vincent
With a brisk wind across our beam, Alaria sailed due south past the verdant mountainous island of St. Vincent to the small island of Bequia over 50 miles south of St. Lucia.  We had all of our sails up so we travelled much faster than we could with the engine.  There is something extremely satisfying sailing to your next study area powered entirely by the Trade Winds!

Alaria under full sail arriving at Bequia
Islands of Bequia and Mustique showing our survey sites
Port Elizabeth is Bequia’s major port and it is where we cleared customs to enter the country of St. Vincent and the Grenadines (actually only the northern Grenadines since the southern Grenadines are the country of Grenada).  Port Elizabeth’s Admiralty Bay has both anchorages and moorings.  We decided to anchor to keep costs down but it was a lovely spot where we watched the sun set into the sea each night.

It is obvious after just walking around for a Bequia for a little while that it is a very friendly place.  When I first went ashore to clear customs, I asked a fellow where the customs house was and he insisted on walking me to the building.  The small town of Port Elizabeth has a ‘light’ feel to it.  It is not crowded, there are enough tourists to keep shops and eateries going.  The open air market is well stocked with nice local produce.

Bequia's Port Elizabeth
In Bequia, we arranged to see Mr. Herman Belmar who is Deputy Director of Grenadines Affairs.  He was eager to have us survey the reefs in the region and especially the Tobago Cays Marine Park.  We went over the charts considering where we could work and where we can anchor.  It was clear he knew the waters around Bequia like the back of his hand.  He knew where reefs were best developed and where fishing pressure will likely be highest.  He also called over to the island of Mustique to arrange for us to work there after a bit.

Mr. Herman Balmar pointing out keep coral reefs in the Grenadines
The Grenadines are really different from anything we’ve experienced so far.  It is an archipelago of small to tiny islands that stretch about 50 miles from St. Vincent to Grenada.  Bequia is one of the larger islands but it is only a bit over 5 miles long. 

The people of Bequia have a tradition of building boats, fishing and whaling.  They have a permit from the International Whaling Commission to take up to four whales a year but often they don’t get one.  They use traditional methods.  They sail to the whale, harpoon it with a hand-thrown harpoon and then float it to a small whaling station on a tiny island off the east coast of Bequia for processing.

Bequia's whaling station
Fishing is important in Bequia.  We saw lots of folks fishing both the inshore reefs and going offshore to catch some of the larger pelagic fish such as wahoo, mahi mahi, Spanish mackerel and small tuna.  Those are the fish I saw landed at the dock.  Pelagic fish are the best choice of fish to eat because they can be fished sustainably.  Unlike reef fish these pelagic fish grow rapidly, they reproduce early and often, and they are abundant. 

Bequia's colorful fleet of fishing boats
Nice catch of fish being filleted. 
Only some fishermen can venture offshore for the larger pelagic fish.  Many people fish with spears, traps and nets the inshore reefs.  Gillnets are particularly destructive because they drape over reefs for considerable distances.  Fish try to swim through the net but their gills get caught. Chancey happened upon one such gillnet as he did his fish surveys.  He photographed lots of large parrotfish caught and dead in the nets.  These nets fish for as long as they are deployed.  If they are left too long the caught fish will rot and not be suitable to sell or eat.   Because there is not much of a market for parrotfish in Bequia,  many (or most) are discarded dead.  The site where the gillnet below was deployed had lower than average parrotfish abundance on the reef according to our fish surveys.

Gillnet strung across a coral reef (photo Chancey Macdonald)
Dead parrotfish caught in the gillnet (photo Chancey Macdonald)
Bequia’s coral reefs are modest in extent (to be generous).  Chancey and I dived on two widely separated of reefs on opposite shores of Admiralty Bay (Port Elizabeth) and then we took Alaria around to Friendship on the eastern side of the island.  There the Trade Winds blow incessantly. We anchored in a corner of Friendship cove but had to set the stern anchor to minimize our roll from a constant swell.

Alaria at anchor in Friendship Bay. 
Because we were on Bequia’s exposed coast, wave action was high on the reef we wanted to study.  So we had to take particular care on how we anchored the inflatable boat, just out of the breaking waves, and we checked the anchor at the start and end of our dive.

This was a high-energy reef so conditions were ideal for seaweed growth.  Normally we wouldn’t see much seaweed because parrotfish and other grazers would keep it mowed down.  However, this is a heavily fished reef according Mr. Balmar and grazing fish densities were low and seaweed was luxuriant.

Fishermen of Friendship Bay
Seaweed dominated reef at Friendship Bay
Overall, Bequia’s reefs were about average for the region.  Areas like Friendship that are heavily fished and where conditions for seaweed growth is good, there is a carpet of seaweed that limits baby corals so the reef is likely to remain degraded for some time.

We had learned from Mr. Balmar, that the reefs around the neighboring island of Mustique are protected from fishing and they are patrolled regularly by Mustique’s security force.  We knew we had to sail over to see if reefs were in fact different there.

Alaria viewed from the groomed shoreline of  Mustique Harbor 
Mustique is unlike any island I’ve visited.  It is a private island owned and operated by the Mustique Company.  It has a board of directors (including folks like Mick Jagger, who is also part of the environmental committee); it is where Britain’s royal family goes when they want a break from the winter chill.  The week before we arrived the Duchess of Cornwall (Kate Middleton) and her baby had been on the island for the baby’s first overseas trip.  The head of security told me in jest that “no photos were taken of them, so I get to keep my job”.

The tiny island of Mustique (only 2.5 miles long) has by far the highest per capita income of any island in the region.  Its economy comprises one quarter of the gross domestic product of the country of St. Vincent and the Grenadines!  When a powerful Christmas Eve rainstorm flooded St. Vincent (as it did in St. Lucia while I was there), Mustique donated a million dollars for the big island’s restoration.

We met with Mr. Simon Humphrey who holds several important positions within the Company but importantly he is the island’s Conservation Officer.  He has a broad view of what is happening on land and in the sea.  He worries about how the island runoff may affect the reefs.  The island has banned pesticides and landscaping looks to minimize erosion. The reefs are all currently protected from fishing.  He also wants to see the protection of the island’s coastal zone extended one kilometer offshore (he knows that will be hard but he’d love to see that happen).

Mr. Simon Humphrey explains the conservation challenges of Mustique
Mr. Humphrey arranged for us to dive from the island’s security force boat while Brian, the dive manager, was busy.  Afterwards, we dived with Brian and the dive team.  On our first dive we saw the value of Mustique’s protected area.  Parrotfish and grouper abundance (biomass) were an order of magnitude higher than the average for Bequia and the entire eastern Caribbean. 

A school of striped parrotfish swim over Mustique's coral reef

Pillar coral and fish along my transect line on a Mustique coral reef. 
We spent the week diving other sites and none quite matched up to our first dive but the average for Mustique.  However, coral cover, juvenile coral abundance, parrotfish and carnivorous fish abundance were all well above average for the region and for the eastern Caribbean.  We intend to return to Mustique to follow up a bit on what might be driving coral reefs around this island.  However, the bigger picture that is emerging is that the socio-economic status of the local area creates the need to fish the coral reefs.  Arguably, Mustique can afford to be conservative but Bequia may not.

The value of coral reefs, as with any commodity, is what the market can bear.  There are some dive operations in Bequia but there are many more fishers so the incentive to conserve the coral reefs is low.  However, truly unique and expansive coral reefs exist around Tobago Cays and there they have the Tobago Cays Marine Park, a fully protected ecotourist magnet.  There we can study reefs where the overwhelming value comes from having healthy and abundant reef fish as opposed to those sold in fish markets.

Chancey looking from Bequia to neighboring islands of the Grenadines

Wednesday, 5 February 2014

St. Lucia: stunning island, surprising coral reefs but challenges everywhere

Petite Piton and fishing boats viewed from Soufriere Harbor
To say the island of St. Lucia is stunning is an understatement.  Its volcanic mountains thrust up into the moist tropical clouds of the Caribbean bringing frequent rains keeping everything verdant.

The rain forest at the Millett Nature Reserve.

However, this small (about 20 mile long) island has only a few economic opportunities.  Tourists are the ‘top banana’ but real bananas are second.  However, they don’t make enough money to support the island population so poverty and begging (on land and in the sea) is common.

Coastal village with fishing boats and a life connected to the sea.

With this is the background lets consider the status and conservation of St. Lucia’s coral reefs.  St. Lucia is well known in among the scientific and conservation community for having developed ocean use zoning well before many countries or islands had considered it.  Their reefs are small because the slopes from the mountains are so great so fishing pressure is concentrated over a relatively small area.   That’s a prescription for rapid depletion of reef fish.  So St. Lucia set up areas where fishing was prohibited and other areas they call “Fishing Priority” areas.  The idea is that if fish stocks build up in abundance and size in the no-take reserves, they will spill over into the Fishing Priority areas.

St. Lucia's progressive marine zoning map for multiple uses.
It appears this worked for a period of time.  However, meeting with the Jeannine Compton the managers of the Soufriere Marine Management Area (SMMA) she tells me that in recent years “compliance is a problem”.  The SMMA region has Rangers who patrol the region daily but areas that are out of sight or everywhere at night has little or no patrolling.

Ms. Jeannine Compton the Director of the Soufriere Marine Management Area (SMMA).

Jeannine arranged for Chancey Macdonald and I to survey all of the important reefs of St. Lucia’s SMMA and CAMMA (Canaries Marine Management Area).  For this, SMMA Rangers would pick us up each day from Alaria for dives at two reef sites.  We did this all week and got a good feeling for the status of St. Lucia’s reefs.

SMMA Rangers Mario Justin (left) and Francois Kerjackie (right).  Great company and wonderful Rangers!

First of all, this is a high island so much of the substrates on which coral could live are boulders that rolled off the island.  They had coral growing on them – and some sites had considerable coral.   What is so odd is how little of the coral accumulated.  I have to assume that as soon as a coral dies in this environment, it gets bioeroded to sediment that is washed away.  That’s very different from most of the Caribbean reefs I’ve studied (e.g. in Belize, Mexico, Jamaica and St. Croix) where as coral dies they leave their skeleton and the reef as a geological structure persists.  Not so with few exceptions in St. Lucia.

Boulder reefs of St. Lucia (but not all reefs are like this)
Stoplight parrotfish grazes a boulder reef.  Strings are from a worm that eats particles that fall on the reef.
The other difference we found in St. Lucia’s reefs is the abundance of the black spined sea urchin named Diadema.  This sea urchin was, until 1984, one of if not THE dominant grazer on Caribbean coral reefs.  In the early 1980s this sea urchin reached population densities averaging over 15 per square meter.  It was a virtual carpet of poison-filled spines that were literally and figuratively a pain in the ass.  Well over 90% of Diadema died throughout the Caribbean and their recovery has been slow or non-existent.  However, at a few sites on St. Lucia’s reefs, Diadema population densities were enough for them to be the dominant grazer.  Where that happens, the seafloor turns pink from the calcifying red algae (called crustose coralline algae or CCA for short).  The reef takes on an entirely new look.  Light reflects off the reef, the water is clear and baby corals do very well.

Two Diadema urchins grazing with pink coralline algae and a few corals (along my transect line)
We do wonder why Diadema has come back to only a few places in the Caribbean.  After a long period where no Diadema were easy to find on reefs, they started to come back… but only to a point.  The pattern often is, they do well in some back-reef environments and they do well at 3 – 5 meters water depth (10 – 15 feet) but not usually at the 10 m (30 foot) depth where we work. 

However, we did find sites in St. Lucia where Diadema thrived at 10 m and we have to wonder why here but not in lots of other places (recall we found NO Diadema in Barbuda). 
Baby (small) corals in a well urchin grazed portion of the coral reef
One possibility is that the key Diadema predators such as queen trigger fish and some of the larger grunts (e.g. bluestriped grunts) and Spanish hogfish are rare or absent at the key Diadema sites.  Our data suggests this may be the case.  Some of the sites with relatively few Diadema predators had the highest abundance of the sea urchin.  While sites with lots of Diadema predators had relatively few sea urchins.  The data are messy and this is far from resolved but it may be that the heavily fished predators allow Diadema to thrive and when that happens the reef appears healthy.  Perhaps in an ideal world, it would be better to have the big carnivorous and big herbivorous fish of yesteryear, but alas, we are not living in a perfect world so the Diadema patch we studied was one of the nicest reefs we’ve seen in the eastern Caribbean!

Sponges, clear water and Diadema ... just a pretty reef!
Some staghorn coral (Acropora cervicornis) a rare but not absent coral in St. Lucia.

Peacock flounder (just pretty)

Very pretty small anemone that lives in a sponge.  It is called Parazoanthus
Fishing is the only option for lots of the folk.  What surprised me was they target ballyhoo and flying fish (by netting them) for food.  Ballyhoo is most commonly used for bait elsewhere but there just aren't many big fish left so this is what they eat.

Fisherman prepares the ballhoo he caught as Chauncey looks on.
Ballyhoo and other fish seasoned for tomorrow meal.
There are also ideas of trying to deploy fish aggregation devices in order to get pelagic fish to stick around.  No one was talking about them so I'm not sure they succeeded.

Fish aggregation device "guarantees bigger and better catch" but I didn't hear anyone talking about them.
Jeannine warned us that poaching within the no-take reserves has been increasing in recent years.   This doesn’t surprise us because getting one large lobster to market would be worth more than a day of begging for money.  While it is arguable that maintaining the marine reserves will sustain a healthier reef ecosystem, when you have no financial resources, liquidating the natural resources to which you have access becomes rational.  Note, that does not mean it is sustainable, just that it is a rational option given the lack of alternatives.

When the Rangers took us to our last site, which is around the back of Gros Peton (the biggest of the two famous pitons), we came across three local guys swimming.  The rangers asked them what they were doing but they had no evidence of having any fish.  Given that we were not within site of any houses, it is unlikely these guys were just out for a swim.  Nevertheless, Chancey and I had to do our surveys so we suited up and jumped in the water.  As we got to work, I noticed a fish trap not far away.  These are clearly illegal and there was a string of them.  Jeannine thinks they are checked and rebaited at night in the dark.

Illegal fish trap in the Gros Peton no-take zone.
Parrotfish (with spots) and other fish in the trap.

I’ve seen plenty of fish traps over the decades but I can’t think of many (any?) with as many fish or the diversity we saw in this trap.  I saw in this one trap, Spanish grunt, French grunts, white grunts, blue tang, ocean surgeon, surgeonfish, stoplight parrotfish, spotted drum, Caribbean king crab (Mithrax) and Caribbean lobster (Panulirus argus).  Obviously the fishing was very good in this no-take reserve.  We reported this to the Rangers and they asked that we open the trap and let the fish go (which we did).  It is unlikely the fellows swimming had anything to do with the traps (they require a boat to service) but everyone agreed that they were undoubtedly fishing but dropped their catch and their spear guns when they saw the Rangers.

The income inequality is striking and we of course were part of that.  Next to fishing villages with no opportunity for work or income are expensive cruising yachts.  St. Lucia is a destination for a range of cruising ships.  Sadly, only a tiny fraction of the wealth from a cruise ship of 3000 passengers is passed to the island community of St. Lucia.

Sailboats and big cruise ships frequent Soufriere Bay, St. Lucia.

As it happens paying for moorings is one of the best sources of income for coastal villages.  But the villagers know it is their job to try to extract as much money as possible from transient sailors.  You cannot tie up your dingy at the town dock without a boy waving at you as you approach to point out the obvious spot where you should tie up.  Then they offer their services to watch your dinghy.  This is worth the few dollars we spent for this because an inflatable dingy is vulnerable (although we had the smallest and dingiest dingy in the harbor).

After being in St. Lucia for nearly two months I could now see and feel the “edge” that divided the haves from the have-nots.  Children would paddle to the boat on a broken found surfboard asking for food or money to take our garbage.  We’d love to support them all but it would be hopeless.  There was also an aggressiveness we encountered from time to time.  People would not take “no” for an answer.  On the occasions when we gave something to one person we’d find a rapid increase in beggars wanting more from us. It is hard to say no to those in need but our giving would not change this situation. 

So it was with mixed emotions that we departed St. Lucia at 5 am under a starry canopy.  As we sailed out, we gazed at the shadows of the conical hulks of the pitons for the last time.  Just above them we saw the famous Southern Cross constellation marking our way south to Bequia (St. Vincent) where we hoped to find healthier reefs and happier communities.

The setting sun from St. Lucia.