MANGROVE DIE-BACK IN THE ABACO MARLS: THE FACTS


Mangroves, The Marls, Abaco, Bahamas (Keith Salvesen, Rolling Harbour)

MANGROVE DIE-BACK IN THE ABACO MARLS: THE FACTS

For some time now, there has been understandable concern about the increasing evidence of mangrove die-back in the Abaco Marls and elsewhere in Abaco waters. Scientific investigations are ongoing and you will find some of the survey results so far on the excellent Abaco Scientist interactive map HERE. You’ll find other relevant and authoritative mangrove material if you check out the BLOG menu of the website.
Abaco - The Marls

The ‘200 sq. miles’ in my map is debatable, depending what one includes. Other estimates are of 300 or even 400 sq. miles. Whichever, the Marls cover a massive area of mangroves, islets, flats, channels and wonderfully diverse wildlife. A large proportion of the many species – fish, birds, turtles etc – depend on the complex ecology of the mangroves for food, shelter and breeding. Depletion of the mangroves from whatever cause will have a direct effect on the creatures of the Marls.

Stingrays Abaco Marls 6

Ryann Rossi, a PhD student with North Carolina State University, has been researching the worrying phenomenon of mangrove die-back in the Marls this summer. She has written an interesting and informative  account (conveniently in the RH ‘Facts about…’ style) that was published in Abaco Scientist last week. The blue links will take you to the ABSCI site for further information on each topic. I’m grateful to Ryann and ABSCI for permission to use the material.

Five Things to Know About the Mangrove Die-back in The Marls (at this point, anyway)

1. This die-back appears to be the result of multiple stressors acting together. Think of it in the sense of our own body – when our immune system is down, we are often more susceptible to getting sick. The same thing is likely happening to the mangroves.Mangrove Die-back 1 (Abaco Scientist : Ryann Rossi)

2. It appears as though a fungal disease may be taking advantage of already stressed mangroves and causing die-back. We did preliminary surveys across Abaco and found fungal lesions nearly everywhere. However, the fungus was present in different densities in different areas. In the die-back area nearly all the leaves remaining on trees have lesions. We think that this pathogen capitalized on the mangroves being weakened by other stressors such as hurricanes, which cause extensive leaf drop, change in the movement of water, change in sedimentation and erosion.

Mangrove Die-back 2 (Abaco Scientist : Ryann Rossi) jpg

3. We are still working on identifying the pathogen associated with the lesions we’ve found. We are confident that it is a fungus and are currently growing fungal cultures in the lab to examine defining morphological characteristics in addition to using DNA sequencing to identify the culprit.

4. We have documented the presence of the Robust Bush Cricket (Tafalisca eleuthera) in the die-back areas as well as other areas with high densities of lesions. These crickets are documented to consume Red and White mangrove leaves. As such, we were concerned about their potential role in die-back. We set out a caging experiment to exclude the crickets from certain dwarf Red mangrove trees to see just how much grazing they may be doing in the die-back area. This experiment is ongoing.

Mangrove Die-back 3 (Abaco Scientist : Ryann Rossi) jpg

5. The take home: there is likely more than one causal agent of the die-back in The Marls. Many factors govern mangrove productivity and functioning: nutrient availability, salinity, sedimentation rate, herbivory, and disease are just a few of the factors that contribute to overall mangrove function making it very difficult to pin point which factors may be driving the die-off. On the bright side, we are confident that we have a lead on the causes and we are working hard in the field and laboratory to fully understand what is going on in The Marls.

By Ryann Rossi|August 26th, 2015|Disease, fungus, Insects, Mangroves and Creeks, The Marls
All pics below taken while fishing on the Marls except Melinda’s shark (I’ve never got a good one)
Hawksbill Turtle, Abaco Marls (Keith Salvesen)Bonefish Gotcha - Abaco Marls (Keith Salvesen)Shark 4 ©Melinda Riger @ G B Scuba copyOsprey - Abaco Marls 1 Reddish Egret (White Morph), Abaco MarlsRoyal Tern, Abaco, Bahamas (Marls) 3Willet, The Marls, AbacoSouthern Stingray, Abaco Marls (Keith Salvesen 4)
FRIENDS OF THE ENVIRONMENT has also included an article on die-back by Ryann in its latest Newsletter:

Mangrove Die Off on Abaco by Ryann Rossi, NCSU

This summer Stephanie Archer and I continued research efforts focused on determining the cause of the mangrove die-off in The Marls (work funded by the National Science Foundation). Our efforts were predominantly focused on the fungal pathogen we found associated with the die-off site. We created a small citizen science and outreach project to document the presence or absence of the pathogen across Abaco. This project consisted of short surveys and leaf collections. In total, 92 areas were surveyed including locations from Abaco and San Salvador. We also took this outreach project to the annual Bahamas Reef Environment Education Foundation (BREEF) teacher training conference.  There we disseminated survey packets to teachers from islands throughout The Bahamas who will help us collect more data on the presence (or absence) of this pathogen on other Islands.

3 men on a skiff, Abaco Marls (Keith Salvesen : Rolling Harbour)

Three men on a skiff – Abaco Marls

On Abaco, we constructed an experiment to investigate the role of grazing and the presence of fungal lesions on Red mangroves. We simulated grazing using crafting scissors to cut small sections on 600 leaves in 4 different mangrove creeks. We observed the leaves for 28 days to determine if cutting leaves predisposed leaves to fungal infection. At these sites we also trapped for insects to gain an idea of what kind of grazers may be chewing on the leaves. We also did a series of disease incidence surveys that will be routinely monitored for disease progress over the next 2 years. These surveys will allow us to systematically track the progress of the disease. In addition to our field work, we spent many hours in the laboratory isolating fungi from leaves to grow in culture. These cultures were brought back to North Carolina State University and will be sequenced in order to help us identify the fungal pathogen responsible for making the lesions on the mangrove leaves.

Mangroves, Abaco Marls (Keith Salvesen)

Credits: Source material Ryann Rossi; Abaco Scientist; all photos © Keith Salvesen @ Rolling Harbour except those by Ryann / ABSCI in the main article and Melinda Riger’s cool shark

SHARING SHEARWATER SEASHORE SHOCK ON ABACO…


Great_Shearwater_RWDz9 Dick DanielsSHARING SHEARWATER SEASHORE SHOCK ON ABACO…

I return reluctantly to the “Great Shearwater” phenomenon to give, I hope, closure to the topic for this season and with luck for several years to come. A great many people have engaged with the debate about the large number unfortunate birds found either dead or dying in the water or (especially) on the beaches of Abaco and beyond. You can see the original post, a tabulation and map based on the reports I received or came across, and the views of the experts HERE

This occurrence appears to have declined considerably from its peak last week, presumably because the migration has moved rapidly northwards. Already, reports from the eastern US Atlantic coast (e.g. Cape May) of a great shearwater influx are coming in, so we must hope that the attrition rate in the Northern Bahamas has stopped, or will stop within the next few days. This is evidenced by this FB clip from Tom Reed, a photographic contributor to THE BIRDS OF ABACO

TR clip

The ABA (American Birding Association) has taken an interest in the problem on Abaco, and reported the incidence of shearwater die-off HERE. For the sake of completeness, I have updated reports I have received or found over the last few days below, together with an updated distribution map. More sad images are included because, pitiful though they are, photographs are of real assistance in the study of migratory die-off. For example, it is likely that juvenile birds are more likely to be affected by exhaustion in the course of their 10,000 mile journey than adults. Photos enable an assessment of the age of the birds to be made.

Exhausted shearwater, Delphi beach. Is this a juvenile, less able to make a huge journey than an adult?Great Shearwater, Delphi, Abaco (Sharon Elliott)The yellow tip to this bird’s beak shows that it is a different species of shearwater, the Cory’s.  Like the Greats, these birds are also rare transients on Abaco, and also make long-distance migrations. A Cory’s was photographed a couple of weeks ago swimming happily off the Delphi beach. This one has obviously run out of stamina. It has the chance to recover, but it is vulnerable in this state; and turkey vultures are quick to move in on fatalities…

 UPDATED REPORTS (SINCE JUNE 24) IN RED
  • Delphi Club Beach – 20 plus + 1
  • Schooner Bay – 5
  • Bahama Palm Shores – ‘many many’ dead birds washed up on the shore
  • Casuarina Beach – 1
  • Cherokee (Watching Bay) – 3 or 4
  • Cherokee (Winding Bay) – 4
  • Little Harbour – 3
  • Marsh Harbour area – about 5
  • Great Guana Cay, southern end   – 1 (possibly a gull)
  • Tilloo Cay – 13 at least on Junk Beach, more than ever seen (see photos below)
  • Elbow Cay – 2 + 1 Atlantic side beach near Abaco Inn
  • Elbow Cay – 2, North End
  • Green Turtle Cay beach – 2
  • Green Turtle Cay, offshore – “a lot in the water”
  • Man-o-War Cay – 1 by the roadside
  • Ocean 20m from HT Lighthouse – 2 in the sea

also Exuma Sound (5 birds), Shroud Cay Exuma (gull?”), Briland Beach,Harbour Island Eleuthera (“some” + 4) , and Church Bay, South Eleuthera – 10 + 2

Ellen Bentz, who reported the Church Bay birds, has frozen 3 of them for research purposes; it will be extremely interesting to see what results from their examination, from the ages of the birds to condition to likely cause of death. She also took photographs to aid species identification and diagnostic efforts.

unnamed unnamed-4 unnamed-2  unnamed-1unnamed-3

Abaco distribution map. Earlier reports marked in green, two new sites in blue
Shearwater Map, Abaco update

Here is the wonderful Crossley ID guide tableau of great shearwaters, showing every facet of the birdGreat_Shearwater_from_the_Crossley_ID_Guide_Britain_and_Ireland
WHERE DO THESE BIRDS COME FROM & WHERE DO THEY GO?
Sean Giery of the excellent ABACO SCIENTIST has also commented on the recent phenomenon, concluding “…if you haven’t looked up Gough Island, the probable origin of these Greater Shearwaters, do. Use Google Maps to get an impression of how far these amazing birds travel. It’s truly amazing.” By great good fortune, I’ve done the legwork for you… Let’s take a closer look.
Great shearwaters breed almost exclusively the small area of the globe that includes the Gough Islands, Tristan da Cunha and a few lesser-known islands in that area. There is also a small breeding population in the Falklands. Whichever, they are not so very far from Antarctica. Their range, however, is massive and involves long migrations over the Atlantic ocean to the far north – as far as the Arctic – and back each year.
gtshearmap
 And, as the shearwater flies, this is the distance from the breeding grounds to Abaco; 2/3 of their total journey. Now, factor in a first-season juvenile shearwater facing the vagaries of food supply, weather conditions and stamina… The fact that some die-off occurs every few years at some stage of the migration becomes less surprising.
Gough Island to Abaco 6300 milesGough Island to Abaco jpg
I’ll conclude with a photo of a great shearwater flying ‘at the shear’, which I am certain is how best we’d like to think of these wonderful seabirds…
Great_Shearwater_RWD3b Dick Daniels
Credits: to the 30 or so people credited in the original post I add with thanks Molly Kemmer Roberts, Susan Drwal, Sharon Elliott, Ellen Bentz, Dick Daniels and open source maps chaps.

RANDY: LOOKING FOR MANATEE LOVE IN ABACO?


Randy the Manatee, Abaco (BMMRO)

RANDY: LOOKING FOR MANATEE LOVE IN ABACO?

Strangely, the opportunistic title of this post may not be as contrived or daft as it looks. The facts are these.

THE FEMALE In 2012 GEORGIE, a young female manatee, left her mum in the Berry Islands and braved the crossing to Abaco. She reached the Marls; went right round top and down the east side; and eventually settled in the Cherokee / Casuarina area. She managed to hole up there safely during hurricane Sandy but became sick and was removed to Atlantis for medical treatment and rehab, before being released back to the Berry Is. This spring she set of again for Abaco and seems to have made straight for Cherokee, where she has now been resident for several months. 

Georgie the Manatee as a calf in 2012, checking out the BMMRO boatGeorgie the Manatee Calf checks out the BMMRO Boat

THE MALE Randy also originates from the Berry Is, where he was born. He too set off on an expedition to Abaco in the spring, presumably following Georgie. He was seen at Gorda Cay in mid-August and then fetched up at Sandy Point. After spending the summer there, he too took a trip right round the top of Abaco and down the east side. By early September he had got as far as Little Harbour. However, the big question is whether he can, in some way, tell that a lady manatee is a shortish swim away. And if so, will he make the short trip down the coast? And might that lead to baby manatees on Abaco…? Here are some of the photos of Randy’s sightings along the way

RANDY AT SANDY POINT 

Sirenians and cetaceans are generally recognised from particular patterns to flukes or fins. The second image shows the notch in Randy’s tail that confirms IDRandy the West Indian Manatee, Sandy Point, Abaco, BahamasRandy the West Indian Manatee (tail), Sandy Point, Abaco, Bahamas

RANDY IN THE LITTLE HARBOUR AREA

Randy’s notched tail is clearly visible in the first pictureRandy the Manatee, Little Harbour, Abaco (BMMRO)Randy the Manatee, Little Harbour, Abaco (BMMRO)

This could be everyone’s favourite picture – almost like a ‘Randy Selfie’ with a GoPro…Randy the Manatee, Little Harbour, Abaco (BMMRO)

RANDY’S JOURNEY & THE DISTANCE BETWEEN HIM AND LOVE…

Excuse me while I anthropomorphise excessively here. Randy may only be appearing to follow Georgie; the route and the area may happen to suit manatees who may be a short distance apart yet completely ignorant of the presence of the other. Or else… Anyway, more news as (if) it breaks. Here are a couple of maps, of the sort that the red-top press might put together to go with the headline “Lovelorn Randy – A Man Manatee Seeks His Sirenian Siren”. Pictures, page 8, 9, 10 and in sports section.

Randy's the Manatee's trip Berry Is. to Abaco copy Page_1 copy 3

STOP PRESS SEPT 21

Oh dear. The course of love is rarely straightforward. Randy has retraced his route and returned to Castaway Cay. Meanwhile Georgie remains happily at Cherokee.

RELATED POSTS

GEORGIE at Cherokee, 2012

GEORGIE” the manatee movie (on location, Cherokee)

GEORGIE taken to Atlantis for medical treatment

GEORGIE Is she related to an elephant?

Credits: BMMRO + Heather Albury, Andrew Lowe & Richard Appaldo for pictures & reports, Loggerhead Productions, Abaco Scientist 

mantsw~1

‘MEN AT WORK’: CLEANING UP MAN’S DEBRIS IN THE OCEAN


bird1

‘MEN AT WORK’: CLEANING UP MAN’S DEBRIS IN THE OCEAN

I keep an eye on the website SCUBAZOO. As ever, the alert ABACO SCIENTIST (highly recommended to follow) has beaten me to this latest post from Jason Isley, diver / photographer and creative thinker. He demonstrates the wonders and (human) blunders of the deep with wit and style. In the gallery below, he tackles the issue of man’s pollution of pristine waters. In a simple way, he manages to use humour to get across a message  that can easily become obscured by lengthy sermonising. See what you think.            

Pollution01Pollution02Pollution04Pollution03pollution06pollution05

SHARK FINS – OOOP! A MODEL USE OF HUMOUR TO CONVEY ASERIOUS MESSAGE (VIDEO)


306092_500604003294327_1470960886_n

SHARK FINS – OOOP! A MODEL USE OF HUMOUR
TO CONVEY A SERIOUS MESSAGE
(VIDEO)

The CAPE ELEUTHERA FOUNDATION has produced a short video about sharks and shark fins that manages to be both amusing and to carry a powerful conservation message. It’s a hard trick to pull off successfully. Attempts to use humour to leaven a serious message or to modify earnestness in presentation so often trespass into the no-man’s land known as ‘Meh’ (twinned with ‘Wotevah’). I’m grateful to the always-interesting ABACO SCIENTIST for sharing this item. Photo credit: Melinda Riger, with thanks for use permission [I am posting this from NYC via iPhone, so any weird formatting or typos will have to be dealt with next week]

ABACO PARROTS & CHICKS – A 2012 BREEDING SEASON PICTURE GALLERY


ABACO PARROTS & CHICKS

A 2012 BREEDING SEASON PICTURE GALLERY

Time to write some more about Abaco’s most famous bird, the unique ground-nesting Amazon / Cuban parrot sub-species that makes Abaco its home, and breeds in the pine forests of the Abaco National Park in the south of the island. You’ll find lots of information and photos on the dedicated page ABACO PARROTS.

This post covers the 2012 breeding season, and highlights the success of scientist Caroline Stahala and her team in helping to secure the future of these rare endangered birds. The population had shrunk to around 2500 (or fewer) some years ago. More recently it had risen to 3000. An intensive conservation program, including anti-predation measures, has proved effective; and a systematic ringing program has enabled the team to keep a close eye on recovering parrot numbers. Caroline says that the population is now in the region of 4000, confirming an encouraging reversal of a dismal decline towards extinction for these beautiful birds.

ABACO PARROTS IN THE PINE FOREST

The parrots breed only in the pine forest, where they nest in quite deep holes in the limestone rock. This makes the nests and the areas round them vulnerable to predation from feral cats and rodents etc; but conversely it offers protection from the forest fires that would destroy tree nests. 

The holes are often well concealed in the undergrowth and take some searching for…

Both parents are involved in the nesting and later chick care. The female lays 2 – 4 eggs.

The chicks hatch after an incubation period of around 26 days

Some of the nest holes are remarkably deep: the parent parrots clamber up and down the sides

The chicks grow the beginnings of feathers, remaining quite unattractive except to their parents

The parent parrots share feeding and care duties

The chicks / fledglings stage are ringed so they can be identified – see ABACO PARROT CHICKS

By coincidence, as I was producing the post above, Craig Layman at THE ABACO SCIENTIST was also ruminating on the topic of Abaco parrot breeding. He posted the comments below, which raise the very interesting question whether the Abaco parrots, with their increased population, may be starting to breed outside the National park. Caroline can probably answer this (see COMMENTS), but does anyone have any direct evidence to suggest a wider breeding habitat? I guess there would need to be a suitably pitted rock structure for the nests, and an absence of the usual cat- and rat-type predators that one might find nearer human populations. Answers welcomed via the comment box…

(Sort of) A Bahama Parrot Study

Posted by laymanc 26 Nov 2012

It isn’t really much of a study, but the only “science” I have been able to do over the last week with the continued turbidity of  nearshore waters.

The Bahama parrot (more information HERE and HERE) is one of the iconic Bahamas animals, and the main factor behind the establishment of the ABACO NATIONAL PARK in southern Abaco.  But my study has been conducted instead from my desk in Little Harbour.  My main finding is simple: the range of the parrot has clearly expanded; it has now been a full calendar in which parrots have been in the area.  Just a few days ago two dozen were squawking around the harbour.  The key will be whether they begin nesting here as well – I havent heard reports of that yet.  But if they do, the expanding nesting range will substantially increase long term viability of the parrot on Abaco.  That ends my first ever Bahama parrot study (I really need more time in the water when I come back).

HOLE-IN-THE-WALL TO GAP-IN-THE-WALL: HURRICANE SANDY SMASHES ABACO LANDMARK


HOLE-IN-THE-WALL TO GAP-IN-THE-WALL

HURRICANE SANDY SMASHES ABACO LANDMARK

A ‘heads-up’ from the excellent ABACO SCIENTIST shows the devastating power of a hurricane-force wind, even at Cat 1 level. After centuries, the eponymous Hole-in-the-Wall has been blasted by Sandy into a Gap-in-the-Wall. Abaco has acquired a new islet, as yet to be named (I propose ‘Sandy Isle’… Or maybe ‘Storm Rock’). The photo below is by Justin Sands, and shows the new view of the southeastern extremity of Abaco. There was until recent times a very similar rock formation on Eleuthera, the Glass Window. It, too, was smashed by a storm and a new road bridge had to be built to link the separated parts (see end of post for image).

This is what the same view looked like until last week, with the ‘bridge’ still standing

Here is a very good close shot by well-known and all-knowing Abaco nature guide Ricky Johnson. There won’t be any more photos like this now… You can see what a large amount of combined wind and wave force it must have taken to blow the bridge apart.

The landmark lighthouse and defunct outbuildings at Hole-in-the-Wall sit just north of a promontory, a sort of Land’s End jutting into the ocean between Abaco and New Providence. The road to it is 15 miles of deteriorating surface through the pine forest of the National Park, and is not for the faint-hearted… see TO THE LIGHTHOUSE

A while ago I traced the history of Abaco, and in particular Hole-in-the-Wall, in maps. I got back as far as 1584 for Abaco itself, a map by Ortelius where Abaco appears as ‘Haraco’ and the geographical relationships are… vague.

The first mention of Hole-in-the-Wall that I managed to trace was on a map by Couvens in 1737. The name is shown as ‘Hole in the Rock’, and that name alternated with the present one in both English and French, with variations, until settling on ‘Hole-in-the-Wall’ in the c20.

To see the full cartographical post see HISTORY OF ABACO / HOLE IN THE WALL IN MAPS

I also researched the pictorial history of Hole-in-the-Wall. Eventually I came across what may be the first pictorial representation of the Hole in the Wall. It is a fascinating aquatint from 1803 by J. Wells, published in The Naval Review and based on a sketch by a ship’s officer that accompanied a description of the southern end of Abaco for the Review. To put the picture’s age into perspective, it was completed 2 years before Nelson’s decisive victory against the combined French and Spanish navies at Trafalgar.

If you are still awake & would like to see the full post, click HOLE IN THE WALL: 1803 DESCRIPTION & AQUATINT

AN ARTISTIC PUZZLE OF LOCATION ATTRIBUTION – A WORK IN PROGRESS

The other notable depiction of Abaco is a print made by (or in conjunction with) the famous artist Winslow Homer, at the time that he was commissioned to produce work in the Bahamas in the 1880s. This print is the subject of ongoing research by myself and others. It is called ‘On Abaco Island’ and clearly shows the Hole in the Wall as we knew it until last week.

Winslow Homer also produced a well-known painting, the original of which is in the Brooklyn Museum, entitled ‘Glass Windows’. It doesn’t take a great leap of imagination to conclude that the painting is based almost exactly on the view in the print. Even if one ignores the geological evidence (eg the structural detail of the rock at the apex of the arch), note the cloud formations that match perfectly. The print predates and was the template for the painting. If the print was the result of Homer’s time in the Bahamas and an undocumented (?) visit ‘On Abaco Island’, so must the painting be…

However, the Homer / Brooklyn painting ‘Glass Windows’ is generally identified with the similar ‘rock hole’ formation on Eleuthera that is actually known as the Glass Window. As I mentioned earlier, the Eleuthera formation suffered the same fate in a storm, and a new road bridge now connects the two sides.Picture credit http://www.eleuthera-map.com (see also http://www.abacomapbahamas.com)

It isn’t easy to tell whether there is any geological similarity between rock structure in the painting and the Glass Window on Eleuthera. However the contention (mine, anyway) is that the Winslow Homer painting ‘Glass Windows’ is of the Hole in the Wall, Abaco and should be recognised as such. The poignancy of last week’s events at HitW – the loss of a well-loved island feature that can never be replaced – arguably makes the thesis more significant.

One further nugget in support of the case is that I have very recently discovered contemporary written evidence that in the second half of the c19, around the time that Homer was working in the Bahamas, the Hole in the Wall, Abaco was known locally as the ‘glass window’. That would explain Homer’s naming of the painting based on the Abaco print, and strengthens (concludes?) the argument that it is, indeed, of Abaco and not Eleuthera. QED. Repatriate Winslow!

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