Ecosystem - a community of living organisms in conjunction with the non-living components of their environment (things like air, water and mineral soil), interacting as a system.
During a day on the water we might see a bald eagle swoop down from its perch high up on a pine tree or catch sight of an osprey diving in its characteristic ‘claws first’ fashion for a fish. Quite often we’ll watch seals eyeing us as we glide by and occasionally a porpoise will surface quite close to our kayaks. And since in a day we’re paddling past literally hundreds of lobster buoys, almost everyone has a question about lobsters – how often the traps are emptied, whether they are fished year round, what’s the word out there on climate change - is it affecting the lobster catch? We see clams, mussels and other shellfish in the intertidal zone on islands along with several species of marine algae. We camp on granite islands which are covered with a layer of acid soil just deep enough for a few species of shallow-rooted trees like pine and fir.
I’m often asked by kayaking clients to include more information on the website about the island environment of Deer Isle and Stonington. So here it is… a brief survey of some of the features of the island ecosystem that we experience here during the summer months.
There are almost fifty bird groups listed in the 'Quick Key to Birds of Deer Isle', a handy booklet written by Marnie Reed Crowell and Kenneth L Crowell and published by the Deer Isle Conservation Commission. There are just a few that we see regularly in the coastal zone in summer.
Twenty years ago it was unusual to see a bald eagle in the area. Now they’re quite commonplace and last year we sighted a bald eagle on about half of our trips. The bald eagle is unmistakable by virtue of its size. With a wingspan of up to six feet or more, to see an eagle swoop down from its perch from atop one of tallest trees, with its characteristic white head and broad dark wings, is breathtaking. I’ve had clients say that the trip was worth it just to see the eagle up close. (Bald eagles, by the way, are not bald - the name derives from an older meaning of the word ‘bald’ which is ‘white-headed’)
Eagles return to same nest each year, so it’s safe to say that on a particular island we’re seeing the same bird year after year. Along with illegal hunting, the pesticide DDT was a major contributor which led to their near-extinction in the 1950s. Interestingly, DDT is not lethal to bald eagles but DDT interferes with calcium metabolism which in the bald eagle’s case resulted in thinning of egg shells. During incubation in the nest, the eggs were quite literally unable to support the weight of the adult bird. The population plummeted until measures were introduced to eliminate the use of DDT and in the 1960s to declare the bald eagle an endangered species.
We’ve seen fewer ospreys in the region in the past couple of years – last year we didn’t see any. It is possible that this is because raptors like osprey and bald eagles compete for territory. Until recently it’s been considered unlikely that an eagle would attack an adult osprey. However, in 2016 there were number of camcorder videos released which showed bald eagles harassing parents and chicks in the nest. One of them, from Hog Island, just 50 miles from Deer Isle shows a bald eagle removing an osprey chick from the nest. (http://www.audubon.org/news/this-rare-video-bald-eagle-attacking-osprey-nest-incredible-display-speed-and. You’ll know an osprey when you see how it catches fish in its characteristic way - feet first in the water. Osprey are one of only two species of raptor (along with owls) where the outer toes are reversible allowing it to grasp a fish with two toes in front and two behind.
Cormorants are colonial birds, related to the pelican, and you’ll see groups of cormorants around Deer Isle and Stonington on rocks with their dark wings outstretched and drying in the sun. They are highly efficient diving birds, diving from the surface of the water rather than from the air like the raptors and using their wings underwater to propel themselves. They have a characteristic dive which gives them a streamlined entry into the water. Since they dive deep, they’ll disappear from view for what seems like minutes. They have short wings relative to their body weight, and they are are poor fliers.
We frequently see guillemots in small groups and in the spring it’s common to come across a pair together with their newly hatched chicks swimming behind them. They belong to the auk family (as do puffins) and are easily recognizable with their black coloration and white wing patches. If you see them out of the water, they’re also identifiable by their red legs and feet which are near to the rear of their bodies, like a puffin. They bob along in small groups in flat and choppy water, occasionally diving then resurfacing to rejoin the group. They have small wings and are not particularly graceful in flight. Their diving and swimming ability, however, is legendary – they’ve been videotaped diving to depths of over 500 feet as they ‘fly’ underwater looking for fish.
We hear loons more frequently than we see them since they are easily disturbed and like to keep their distance. They have an eerie, characteristically mournful call. Often, particularly late in the season we’ll see them up close on the water in the early morning. The loon has unmistakable markings, a black head with a cross-hatched gray body and a dark ring around its neck. If you are close enough you can see that their eyes are red or dark brown. They are the size of a large duck but is distinguishable from a duck in that they seem almost to be in the water rather than on it - the rear part of their body is submerged when swimming. Getting off the water into the air is difficult – you’ll see them running across the water flapping their wings trying to get airborne since their bodies are relatively heavy. Once in the air, however, they are tremendous fliers and have been recorded as flying more than 1000km in a day.
Gulls need no introduction. It’s no accident that they that they are found in such a wide range of habitats - not only on the coast. They are among the most generalist feeders of all birds, in the air they are wonderful fliers, on land they can walk and run efficiently, and in the water, they are expert divers and swimmers. They are colonial, nesting and feeding in groups. They are highly intelligent with a whole range of methods for finding and catching food. We often see them dropping shells of clams or mussels onto rocks to get at the shellfish inside. They’ll fly some distance to find a ‘good’ rock for breaking shells and there is even a learned component to this activity in that older gulls seem to be better at it than the young ones. The technique is unique to gulls. Gulls mate for life and they return to the same location each year for nesting.
The Blue Mussel is a bivalve molusc and is an unmistakable feature of the intertidal zone and found on all the islands around Stonington and Deer Isle. You´ll find their single shells scattered on beaches at low tide and you´ll see live mussels attached to rocks either singly or in clumps. If you look closely you´ll see the fine threads on their feet which allow them to attach and hold tightly onto rocks as the tide comes in and out. When the population is reduced in a particular area they tend to aggregate into clumps of individuals, attached to each other with these same fine threads, and it´s thought that clumping may increase reproductive success in low density populations. Immature mussels are preyed upon by a variety of other invertebrates. The adult is preyed upon by seagulls which you can see picking them off the rocks, flying thirty or so feet in the air and then dropping them onto rocks to crack their shells - it´s as though the seagulls know just how high to fly to do this with maximum effect.
Found between low and high tide marks, the intertidal zone is familiar in that when we land on, or leave from, an island this is where we're standing. It's where we may find a gentle sandy slope, perfect for sliding out of or into a kayak or alternatively it's where we're in churning waves or breaking surf, finding our boats the playthings of the waves. It's where we sometimes struggle to go efficiently from land to sea. It's where we spend a lot of time on overnight trips waiting for dinner or in the mornings drinking coffee wandering on granite outcrops or on beaches made entirely of shell fragments. We see seagulls dropping clams on rocks to break them open, hermit crabs scurrying to keep pace with the moving tide, mussels and barnacles clinging to rocks, periwinkles scattered like marbles in the sand.
Organisms in the intertidal zone are adapted to an environment of harsh extremes. The intertidal zone is also home to many several species from different taxa including Porifera, Annelids, Coelenterates, Mollusks, crustaceans, Arthropods. Water is available regularly with the tides but varies from fresh with rain to highly and dry salt with drying between tidal inundations. Wave splash can dislodge residents from the littoral zone. With the intertidal zone's high exposure to the sun, the temperature range can be anything from very hot with full sun to near freezing in colder climates. Adaptation in the littoral zone allows the use of nutrients supplied in high volume on a regular basis from the sea, which is actively moved to the zone by tides. Edges of habitats, in this case land and sea, are themselves often significant ecologies, and the littoral zone is a prime example.
A typical rocky shore can be divided into a spray zone or splash zone (also known as the supratidal zone), which is above the spring high-tide line and is covered by water only during storms, and an intertidal zone, which lies between the high and low tidal extremes. Along most shores, the intertidal zone can be clearly separated into the following subzones: high tide zone, middle tide zone, and low tide zone.
Trees and plants
Crustaceans – lobsters, clams, mussels, sea urchins
Cetaceans – seal, porpoise