‘BEAUTY & THE BEACH’: A CLOSE LOOK AT SOME ABACO SHELLS
UGLY BUG BALL…
All shells – & the spider crab carapace – collected from the beach at Casuarina
UGLY BUG BALL…
All shells – & the spider crab carapace – collected from the beach at Casuarina
On 26th October 2012, the ‘roof’ of the geological feature at the southern tip of Abaco known for centuries as Hole-in-the-Wall was blasted apart by Hurricane Sandy. The combination of huge waves and powerful winds proved too much for a structure that had existed since the last ice age. I posted in detail about this event last year HERE so now I will concentrate on some geological aspects.
The photo below shows the Hole a year or so before its destruction. At the left-hand end of the bridge there is a paler area underneath where limestone rock had recently fallen into the sea, suggesting an underlying instability. At close quarters there were plenty of cracks in the apparently solid structure. (I’ve no idea why I didn’t straighten the image. Let’s say… Artistic Perspective)
This photo was taken a few days after the collapse, the first to be published of the new view. The clean white rock at either end of the ex-bridge is clearly visible. The section on the left became a new islet at the southern extremity Abaco, separated from the mainland for the first time in history. I proposed various names for it (not all serious) – Sandy Cay (or Isle) was the clear, indeed obvious, winner…
This close-up of the south side of the bridge shows the detail of the rock fragmentation. Tara’s photographs are (as far as I know) the very first of the new gap and of Abaco’s new islet, predating John Haestad’s by a day.
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We recently went to a beach near Crossing Rocks that we had never explored before (plenty of interest there for later posts). We were struck by the fragmented and pitted nature of the limestone rocks on the shoreline. We noticed some pale exposed rock surfaces, similar to those at Hole-in-the-Wall. We watched the incoming waves scouring and undercutting the rocks, leaving overhangs (see video below). Erosion is increased by the double action of the waves. The immediate area hinted that there may even have been a very small Hole at one time. On the day we were there, the sea was gentle. It’s easy to imagine how the hugely destructive force of the wind and crashing waves resulting from hurricanes such as Sandy can eventually shatter solid rock that has been gradually eroded and destabilised over centuries by wave action.
Photo credits as shown / RH. You have Mrs RH to thank for a shorter (50 secs) video than the one I originally made (75 secs). Now I’ve redone the thing, I agree – one wave does look very like the next…
ADDENDUM Just remembered that I took an aerial photo of HitW from the plane the other day. It’s a phone photo through BahamasAir window glass, and I’ve had to tweak it a bit. It shows the relevant area…all the blurry dark stuff is part the pine forest of the National Park
ADDENDUM 2 In response to a comment about the power of hurricanes, here is an image I have posted previously of a large rock some way out from the Delphi beach. Before Hurricane Irene in 2011, it was a solid rectangular slab. This is what it was like after Irene had moved on northwards
Bonefish are difficult to see in the water at the best of times. Shining silver out of water, but pale grey shadows underwater. Fishing under cloud cover and / or (especially ‘and’) when there’s a ripple on the water can be atritional. Sight-casting becomes impossible, and the best recourse is to locate the cloudy patches of water that show where the fish are feeding on the bottom. Chucking the fly into – or beyond – one of these and stripping back may be the only way to get a fish in such adverse conditions. What’s needed is clear sky, sunlight, good polaroids, patience, and keen eyes to scan the water for dark shadows moving across the sand… Or, in my case, simply waiting for the guide to hiss “Hey! Rolling Harbour. Three fish, 40 feet, 10 o’clock moving right, see them? Go now!”. By then, there’s a 50 / 50 chance I may have located them and got my act together enough to (try to) cast at them…
Two days later we went to Casuarina with friends who wanted a day’s wading on the extensive flats there. This photo shows a juvenile fish close to the beach there, on a glorious sunny day with a light breeze (the header picture [double-click] was taken the same day - low water over pale sand as far as the eye can see). I’d never have noticed this little fish, had I not seen the dark shadow it cast on the sand, magnified by the distorting effect of the ripples.
Without the distortion from surface ripples, the bonefish shape can be clearly seen. It’s hard to imagine that by the time this little fish has reached a weight of 2 lbs, he will be capable of stripping your line down to the backing in seconds… or could he?
“Since May 2011, Christopher Haak, a PhD student (and avid fisherman) at the University of Massachusetts, Amherst, along with other scientists, has been trying to solve the mystery of where juvenile bonefish live, from settlement through the time they join adult populations on the flats. Exhaustive efforts to locate juveniles along the densely-developed coastlines of Florida were met with little success, leading researchers to the comparatively pristine shorelines of The Bahamas to continue their search.
For the past one-and-a-half years, they have scoured the coastlines of South Eleuthera, conducting 1000+ seine hauls, encompassing a broad range of coastal habitats. This project is funded by Bonefish & Tarpon Trust and based out of CEI. These efforts (with the help of South-Eleutherans; thanks Denny and Kelsey Rankin!) have succeeded in locating over 800 juvenile bonefish as small as one inch in length, and have revealed some intriguing trends. For example, contrary to what might be expected, juvenile bonefish do not appear to frequent the mangrove creek systems or expansive tidal flats commonly used by adults, preferring instead to remain along shallow, sheltered shorelines near deeper basins or channels.”
“Perhaps the most remarkable finding to date is that nearly every bonefish collected was in the company of much greater numbers of like-sized mojarras (a common schooling baitfish known to Bahamians as shad). These juvenile bonefish exhibited markings and coloration not apparent in adult bonefish, but very similar to the mojarras with which they were caught. By blending in with considerably greater numbers of the model species, the mimics may be reducing their predation risk, and increasing their chances of survival. In the case of bonefish, this hypothesis would also explain why juveniles are so rarely observed; they are well hidden within schools of mojarras! From a conservation perspective, this suggests that bonefish populations may be dependent upon healthy mojarra populations, important information for resource managers.
This research is also producing valuable information about the diverse juvenile fish communities that inhabit Eleuthera’s shores. Myriad seine hauls of the island’s beaches, bays, sounds, and creeks have catalogued juvenile fishes from a wide array of species, including other flats inhabitants like permit, reef fish such as parrotfish, jacks, and wrasses, and some very unusual demersal critters such as shortnose batfish. The high densities and diversity of juvenile fishes revealed by this study serves to highlight the importance of these nearshore habitats to healthy adult fish populations of all kinds, underscoring the need to preserve and care for our coastlines.”
ADDENDUM With thanks to Aaron Adams of the BONEFISH & TARPON TROUT for use permission, here is a great size indicator for baby bonefish, taken by him some years back in connection with a juvenile bonefish project.
The legendary CONCH SALAD TV is a great resource for Bahamas wildlife and way-of-life enlightenment. Their instructive videos are very well put together, and cover Nature, Marine, Art, Science, Music, Culture, Cooking, and broader Bahamas issues. The video below is 9 minutes of Bottlenose Dolphin action, and is recommended for relaxation, gentle instruction, and Kalik-swigging accompaniment…
It time to catch up with last month’s Cetacean sightings around Abaco. The Manatee reports are of Georgie in the Cherokee area – alas no longer resident on Abaco but safely at Atlantis where she is being cared for. To know more about the Blainville’s beaked whale on Abaco, click HERE
BMMRO’s executive director DIANE CLARIDGE has been awarded her PhD by St Andrews University for her research on beaked whales. Dr Claridge’s new status is celebrated by humans and cetaceans alike (see image ©BMMRO below…)
BLACK & WHITE WARBLERS (Mniotilta varia)
WINTER VISITORS TO ABACO
By no stretch of the imagination are the images below very impressive. Sorry about that. The wonder is that we noticed this little bird at all – also, that it stayed still for long enough for me to get a bead on it. I credit the sharp eyes of Mrs RH (from whom little is hid) for spotting a fleeting movement on a pine trunk along the Delphi drive. Unlike any other warbler, these small birds feed in the manner of nuthatches or tree / brown creepers. They run rapidly up and down tree trunks and branches foraging on insects in the bark with their sharp little beaks.
The next 2 photos (yes, I agree, they’re not very good, nor taken – the top one, anyway – from an elegant angle) are included to demonstrate the remarkable length and dexterity of the bird’s legs. During the minute we watched it before it flew off, we noted this characteristic legs-splayed ‘pausing pose’ several times.
We passed these fine Royal Terns during the boat ride ride out to the bonefishing grounds of the Abaco Marls. The single dead tree lay alone in a vast expanse of open water near the mangrove swamps, providing a perfect perch and vantage point for the birds. Their positioning on the tree suggested a distinct “pecking order”, which turned out to be literally true. The terns were unembarrassed by our presence, but at one stage they all took off and circled lazily round once before settling back on the tree. Those that tried to take a higher perch were aggressively treated by the original occupant. In the end, things settled down much as before. However, one disappointed claimant to promotion was dispossessed of the main trunk entirely. He ended up, uncomfortable and huffy, on a small stump facing the opposite way to the rest of the birds – perhaps from wounded dignity, or to make his feelings known through body language….