For those of us relatively new to island conservation,
picking up on all the island lingo can be tricky. What is an atoll? (And how do
you say it?) How do you know if a species is endemic or just indigenous? And
why are mangroves so important?
To answer these and other questions, I've compiled an island
cheat-sheet. Read on for the first post in Seacology U's Islands
101 lecture series!
Island Geography
While some island
features, such as mountains and beaches, are well-known, others might be less familiar
to land-lubbers.
Archipelago An archipelago is a cluster of small
islands. There are hundreds of archipelagos around the world; the largest, Indonesia,
has been the site of many Seacology
projects. Archipelagos are often formed when underwater volcanic activity
causes magma to create rock formations that eventually reach the water's
surface.
Atoll: An atoll is an
island of coral that encircles a lagoon partially
or completely. Many of the islands where Seacology works are atolls, such as Manihiki
Atoll in the Cook Islands. Like
other island types, atolls are formed from the subsidence of an ocean volcano. Corals
grow around an underwater mountain or volcano, gradually building upwards
toward the water surface, while the mountain sinks. Eventually, the layers of
dead coral become islands surrounding a lagoon.
And it's normally pronounced A-toll, as in "Yay, toll for this island is free!"
You can see an example of an atoll in the picture to the left, and find more information on them here.
Lagoon: Though not exclusive to islands, lagoons form
in atolls and near other island features. Lagoons are shallow pools, with
either salty or brackish water, that are separated from the ocean by thin
barriers, such as sandbanks or coral. While many beautiful creatures
can be found in lagoons, Seacology's projects, such as our work in the Cook
Islands, focus protecting highly productive lagoon ecosystems from
exploitation or development.
Island Ecosystems
Although islands host
a wide range of environments, Seacology's work often focuses on certain
critical ecosystems.
Coral Reefs: Coral reefs are complex and highly
biodiverse marine ecosystems. They are built on corals, an animal whose calcium
carbonate exoskeleton forms a strong foundation for other underwater plants and
animals. Reefs are usually found in shallow tropical waters, although some deep
water reefs exist. They are highly sensitive to climate change, since increased
carbon dioxide in the oceans (from released greenhouse gases) prevents the
coral from properly forming the exoskeleton, which causes harm to the entire
ecosystem. With the many threats to coral reefs today, Seacology has frequently
funded coral protection projects, such as one Kimbe
Bay, Papua New Guinea. You can learn more about ocean acidification here.
Mangrove: Mangrove can refer to a specific type of
tree; usually, however, the term "mangrove" indicates the wetland ecosystem
that mangrove trees foster. Adapted to thrive in salt water wetlands, mangrove
swamps (also called mangrove forests) are found on tropical coastlines around
the world. The large roots of mangrove trees keep the trees anchored through regular tidal
changes in water level, while other adaptations allow them to access oxygen,
release excess salt, and bear seeds that will grow even in the harsh wetland
climate. (You can see these unique roots in the picture at right, courtesy of Wikimedia Commons.) Like other wetland ecosystems, mangroves are critical because of their
ability to filter contaminants and protect coasts from erosion. They also serve
as fish nurseries, providing important habitat for many young fish. Mangroves
are currently threatened by coastal development, overfishing, harvesting of
trees, and climate change. Seacology and many other organizations are
encouraging mangrove
restoration projects that will renew these fragile ecosystems and protect
their islands.
Rainforest: Most people associate rainforest with the
Amazon or Congo,
the world's largest tropical rainforests. But much of the world's rainforests can
also be found on islands--Indonesia
alone has 10% of the remaining tropical rainforest. Since rainforests are the
most biodiverse terrestrial ecosystem in the world, preserving them is critical
to the health of the planet. Seacology has funded many projects protecting rainforests
in Indonesia and on other islands.
