Realms of Sand

In this guide, we have chosen to consider both the dune system and the sandy beach as one ecosystem, as these two areas are tightly intertwined and effect one another greatly. While we encourage visitors to appreciate the area, keep in mind that the ecosystem is very delicate and it only takes a few careless acts to ruin the beach forever. Coexist with nature and please do not walk on the dunes!

Sandy beaches are areas of sand exposed between the extreme high-tide and extreme low-tide marks. They are for the most part low lying and flat. The bulk of sand on the beach is derived from the weathering and decay of rocks. Every grain of sand on New England beaches has a long and eventful history. Before it became sand, the grain was crushed by glaciers and ground and polished by the surf. The boulders and cobbles washed in by northern seas represent stages along the way from primal rock to sand grains; the end result of this erosion process is a fine-textured silt.

The term “sand” denotes a specific range of sizes within a sediment classification based on particle diameter ranging between 1/16mm and 2mm. The greater part of most beach sand consists of quartz, the most abundant of all minerals, found in almost every rock. It is also the most likely to survive grinding. Many other minerals are found among the grains as well, such as feldspar, also light in color, distinguished from quartz by its lack of glassy luster.

Certain dark particles found in a handful of sand are in fact garnets of deep purplish red, whose larger fragments can be used for jewelry. You may often see patches of darker colored sand on the beach. This is due to selective sorting by the wind. The wind may be strong enough to blow the quartz grains higher up on the beach, but not powerful enough to sweep away the heavier minerals, and so they are left as separate, distinctly colored patches. The blowing and sorting of sand grains by the wind also build up dunes, which are in essence the extension of a beach, rising above on the beach in the inland side.

Dune habitats are exposed shoreline systems of one or more sand ridges derived from wind and wave transported material. The extent to which a coastal dune system will develop depends upon the sediment supply, degree of erosion and stabilizing plant growth. Nonetheless, every dune system has a successional sequence, only some are more developed than others.

The sandy beach is the first part of the coastal ecosystem and sits directly in front of the dunes. The first portion of the dune system is the area seaward of the frontal dune ridge and is referred to as the fore dunes. It is formed after periods of sand accumulation by the wind and is distinguished by its comparatively low vegetative density due to insufficient nutrients. Beach grass usually represents the dominant form of plant life on the fore dunes.

The back dunes are dry dunes that form inland of the frontal dune ridge. They are commonly composed of larger dunes with a higher density of vegetative cover due to greater organic and water content in the soil.

The dune ecosystem has a low species diversity in the early stages of succession. Primary production is sparse due to low nutrient levels and exposure. On a sequential dune system, bare sand is stabilized by beach grass. As the stable soil increases organic content and water retaining capability, the beach grass community is replaced by a variety of species

The flora

The Flora-Our Sandy Beach-Acadia Oceanside Meadows Inn

Due to many stress factors such as land accretion, erosion and exposure to salt spray, plant life is very limited in both diversity and abundance on sandy shores. The plants that are able to survive in these regions have been forced to adapt to the harsh environment. Their adapations primarily facilitate resistance to desiccation (drying up) and competition under stress. 

They maintain themselves on the upper levels of the sandy beach above the farthest line of blackened rockweed left by the tide where the dunes begin to form, thereby referred to as dune plants.

There are several dune plant communities living in the different portions of the dune system, which we can characterize by dominant species and sub-associations.Realms of Sand-Acadia Oceanside Meadows Inn

The dune grass community, dominated by beach grass, is found on the fore dunes. Beach grass, also called marram grass (from the Latin “mare” – the sea), is characterized by its rapid growth after burial. It can survive up to one meter of sand burial and, in fact, is healthier when buried by a few centimeters of sand each year. Beach grass is abundant on Sand Cove beach at Oceanside Meadows. Beach pea and gooseberry are species often present in the dune grass community in addition to beach grass. Keep an eye out for these plants as you walk down to the shore.

The dry dune slack community is found on the back dunes, where salt spray and sand burial rates are lower than those at the dune grass community. Beach heather is the community’s dominant specie, its occurrence significant since there are probably fewer than 100 acres of this plant in Maine – and some of those are at Oceanside Meadows! The presence of lichens, fungus-algae symbiotes associated to the dry dune community, is a result of the high incidence of coastal fog.

The shrub community is a community of dense tangled bushes consisting of several species. Thickets of beach plum and bayberry are interspersed with Rosa rugosa, or ‘salt spray rose’, a rose able to survive exposure to salt spray that is fatal to other roses. Above the reach of the waves in the sandy inland areas grows a shrubby, evergreen plant with very small leaves: the broom crowberry.

The fauna

For most of the fauna of the sand beaches, the key to survival is to burrow into the wet sand and survive below the surface layers, lest become a snack to predatory fish and birds. The fauna is increased in both diversity and abundance in sheltered conditions, where the sand grades into sandy mud. Polychaetes, bivalves, mud snails and echinoderms are typical in the muddy flats.

As a subsurface deposit feeder, the lugworm is a common species in the area. The worm lies within the sand in the shape of a “U”, with its posterior end close to the surface. Clams are also inhabitants of the muddy bottoms. They have shells made of two halves (hence the name “bivalves”), hinged together with large muscles to keep the shell shut tight. They also have a foot for burrowing and two siphons.

Clams push the siphons through the sand to draw incoming water through their gills, extracting oxygen and trapping food particles that are sent to the mouth. Many snails also live below the surface of sandy mud. The moon snail hunts blindly through the dark sand in search of clams. Upon contacting its prey, the moon snail holds the victim in place with its strong foot and drills a hole through its shell, out of which it sucks the soft tissue. A chain of small parchment capsules, one end free and the other buried under the sand, indicates that a whelk lies below, laying and protecting her eggs.

Mud snails share their dark environment with several echinoderms. Sand dollars live beyond mean low water on top of or just beneath the surface of sandy or muddy areas. The spines on the somewhat flattened underside of the animal allow it to burrow or to slowly creep through the sand. Fine, hair-like cilia cover the tiny spines. These cilia move food to the mouth opening, which is in the center of the star shaped grooves on the underside of the animal. Heart urchins are also echinoderms buried within the sediment of the sea floor. Sandy shores provide important feeding grounds for a variety of shore birds, including sandpipers and plovers. Flounders and other fish come in to feed at high tide.

Many small animals reside on the inland side of the sandy beach. Toads occasionally wander along the far edge of the dunes. Dune grasshoppers as well as beetles are common inhabitants of the dunes. Tiger beetles live in sandy areas such as sand dunes, often away from the water. Sadly, many beetle species, such as the northeast tiger beetle, are endangered. They have disappeared from many beaches along Northeast America because of off-road vehicle use and excessive human trampling. 

Many microscopic organisms are adapted for living in the spaces between sand grains and are referred to as the “meiofauna”. This group includes representatives of every major phylum of animals that are vital to the coastal ecosystem.

Three Little Whelks from Poole

Three little whelks from Poole are we,

Filled to the gills with whelk-like glee,

Univalve all, as you’ll agree,

Three little whelks from Poole!

Every part of our shells is grey,

That’s of nought in the mud anyway,

Here on the estuary floor we’ll stay,

Three little whelks from Poole!

Three little whelks all quite unwary,

Live on the bed of an estuary,

Under the keel of the harbour ferry,

Three little whelks from Poole!

Three little whelks from Poole!

One little whelk is enticed by a crumb,

Caught on a hook from a boat, come, come,

Served in a chowder, yum-yum-yum!

Two little whelks from Poole!

Two little whelks from Poole!

Two little whelks having reached their coda,

All of the genus Gastropoda,

Slightly possessed of a fishy odour,

Two little whelks from Poole!

Two little whelks from Poole!

- Anonymous