Pink sand beaches might be what attracts visitors to our shores, but only ten percent of our island’s shoreline is actually a beach. Ironically, however, the islands of Bermuda are nothing but fixed sand dunes sitting on an extinct volcano. Also incongruous is the fact that some of the greenest leaves, brightest flowers and most fascinating eco-systems can be found flourishing in one of the saltiest, windiest and least nutrient-dense environments around.
Taking The Bermudian for a walk through the sandscape from Warwick Long Bay to Chaplin Bay is geologist Robert Chandler who, despite complaining about his age and eyesight, has the remarkable ability to spot tiny “sand fleas,” fast-moving ghost crabs and knows the Latin names for nearly every living thing we see. “No two beaches are the same,” he begins. “Some have sand dunes at the back of them, others don’t. There are more beaches on the south shore, which is a high energy environment. Less beaches on the north shore.
“South shore beaches tend to be a little steeper. North shore beaches have less gradient on them. Some of our beaches are pink, some are ephemeral.” By ephemeral, he means they come and go.
Sand
The pink, he explains, is a single-cell organism called foraminifera, which thrives on the offshore boiler reefs: “The proximity of the reef here, to the beach, is very close, so we have a lot of pink. Where the beach is further away from the reef, particularly the boiler line, there is less pink.” This is why you won’t find pink beaches on the north shore. The rest of the “dead stuff,” as Chandler refers to it, is made up of calcium carbonate from organisms such as green, brown or red coralline algae, which produce a skeletal frame, and a variety of shells that get broken up and washed ashore along with sea urchins and other calcareous material. This “dead stuff,” however, is a magnet for life, particularly beneath the surface, where it provides homes to a myriad of microscopic organisms called meiofauna. These include roundworms, bristle worms and tardigrades, as well as larger creatures such as the ghost crabs.
Intertidal Swash Zone
The most active area is the intertidal swash zone, where shore birds can often be seen running down to the water looking for something to eat, and then, like small children, running back up again quickly to avoid getting wet feet. “If the ratio of plankton and diatoms in the water is just right, a breaking wave will foam,” says Chandler. “Sometimes you can get foam that stays like soapy suds in the kitchen basin.” The onshore wind and waves, he points out, create a steep step called a berm. On the day we visit, this can be seen all the way down the beach and “is an indication that the waves in the past few days have been a little stronger and it’s done some erosive work.” Another example of erosive work is when waves come in at an oblique angle to the shoreline. This is more common in the winter when the wind direction changes and becomes more intense. As the wave energy washes back down, it deposits sand, creating, he explains, “little scallops, repetitive in the beach, about 20-feet wide, called beach cusps.”
Wrack Lines
When walking along a beach, Chandler is always fascinated by what he might find in the wrack line, also known as a strand line. These are the drift lines from what the last tide or storm has brought in. Wrack lines are a crucial feature of sandy beach life for two reasons. Firstly, they provide the foundation on which sand dunes build, and secondly, they provide food for birds and nutrients for the meiofauna and other life beneath the surface. Nowadays, sadly, these wrack lines are comprised of man-made as well as natural materials, especially plastic and discarded fishing gear, which can be deadly to marine and bird life. The most common natural material found in the wrack lines is sargassum, in particular Sargassum natans, which has a spike at the end of its float bubbles, and Sargassum fluitans, which doesn’t. When you flip it, the sand hoppers, also known as sand fleas, start leaping about. “They’re not fleas, they’re not insects; they’re crustaceans,” says Chandler. “This is what some of the shore birds are after.”
Dune Building
This area of the south shore is famous for its sand dunes, and these start with the wrack line. “What happens is, onshore wind blowing dry sand will go through this seaweed and lose a little bit of its energy as it’s carrying material on a windy day,” explains Chandler. “So, sand gets deposited slightly behind the strand line, and then forces the wind up and over the little hump that’s been deposited, little eddy current on the back side, and so more sand is deposited, and slowly, we have a dune starting.
“In fact,” he continues, “dunes themselves form all of Bermuda. As we travel the highways and byways, you’re travelling over sand dunes that have been deposited during the last ice ages. There have been six dune building periods in the last two million years, which we call the Pleistocene.” These dunes have been fixed by plants and the chemical process diagenesis, which turns them into rock.
Dune Vegetation
Keeping these south shore sand dunes in place is a mass of trees, plants and grasses, the most striking of which on the day we visit is the seaside morning glory, which thrived in the late summer rain. It not only covers the base of the dunes, but its long runners, with their striking purple flowers, cascade down onto the beach. These runners maximise the plants’ rainwater collection capabilities. Chandler describes this vegetation as xerophytic halophytes. Xerophytic means a plant has adapted well to survive in an environment with limited water and a halophyte is a salt-tolerant plant. “Any of these leaves, you can lick it and taste the salt,” he says.
Another common adaptation is very deep roots, such as those of the tassel plant. “It looks like little curtain tassels that you would have on your curtain tiebacks,” he points out. Dune vegetation also has the ability to grow quickly because “they don’t know about the next storm that might wash them away, so they have an urgency about their life cycle.” This is particularly the case with “pioneer plants” such as the seaside morning glory. “Pioneer plants are very important after big storms washed away the base of the sand dunes. They come in and get the whole fixing of the dunes started again,” says Chandler. Sandscapes are always changing, but nothing has transformed them more than invasives, such as the casuarinas and Hawaiian naupaka. The acidic needle fall of the casuarinas alters the chemistry of the soil and the thick layer means understory plants can’t grow.
The Hawaiian naupaka, also known as the Hawaiian half-flower, first appeared in Bermuda around twenty years ago, probably via a seed that survived a journey from the Pacific to the Atlantic. It is now starting to dominate these dunes. Its interesting flowers have five petals facing downwards, and the top half is missing. There is also a Bermudian naupaka, but sadly that is now less common. Another invasive we see is the Australian umbrella tree, which has big leaves hanging down.
As we walk through the dune field west of Warwick Long Bay, we notice several buckeye butterflies. “Males need salt to produce sperms and so they’ll land on leaves and try to take up salt,” explains Chandler. Moths are also common here at night. There is one that covers itself in the pollen of the yucca plant, which only flowers in the evening. It then flies to another flower on a different plant and fertilises it. That plant then produces seeds, the moth lays its eggs where the seeds are developing, and then the pupae have food when they hatch. Another moth-pollinated flower is the seaside evening primrose, which again, only flowers at night. We are lucky enough to catch a glimpse of yellow though, as it is a cloudy day so it hasn’t withered and fallen yet.
In spite of the large number of invasives, we still enjoy seeing the beach croton, prickly pear, seaside goldenrod, bay grapes, ink berry, iodine bush, bay bean, spider lilies, and tamarisk bush. We also stop to smell fennel and common sage. “It used to be used by the early settlers for cleaning their teeth,” says Chandler of the sage, which has a slightly rough texture.
Also abundant on these dunes are West Indian seashore rush and burr grasses, the latter being the reason you never want to go off-trail with bare feet. In spite of the potential for prickly feet, however, “it’s a wonderful environment,” says Chandler. “It’s a margin between the vast wilderness of the open ocean and terra firma.”s for Gray who would bring her children down regularly when they were young. Since this time, the landscape has changed very little, but the life has varied. There are many more West Indian topshells, but far fewer fish. West Indian topshells are a protected species, which has helped them to thrive, and Gray strongly believes that such protections need to be extended. “If we want the ecosystem to stay intact, habitats should be protected, not the individual species,” she says. The rocky shoreline, for example, and everything in it.
