1.3.1 The ecological processes of the NWHI ecosystem
are dependent on the health of its vast, diverse coral reef tracts.
Often called the “rainforests” of the sea, coral reefs
are vital to maintaining the biological diversity of the oceans (Citizen’s
Guide 2006). The pristine coral reefs of the NWHI are the foundation
of a symbiotic community composed of countless millions of plants
and animals dependent upon one another for survival (Citizen’s
Guide 2006). These reefs perform important ecosystem services including
filtering water, protecting islands from sediment deposition and storms,
and providing nourishment for marine organisms.
1.3.2 Thousands of species depend on the coral
reefs of the NWHI. Hawaiian monk seals, a majority of which make their
home in the NWHI, are the only surviving marine mammal that is dependent
on coral reef ecosystems (Citizen’s Guide 2006; Cousteau 2003).
The high incidence of apex predators such as sharks, jacks, and groupers
also depends on the high productivity of this ecosystem. In turn,
the prevalence of apex predators has a significant effect on the structuring
of the fish assemblage of the area, impacting the diversity and relative
abundance of species lower on the food chain. Thus, adverse impacts
on these apex predators could cause populations of smaller fish to
quickly become unbalanced, changing the trophic structure and order
of dominance within the ecosystem (Maragos and Gulko 2002; Friedlander
and DeMartini 2002; Suthers 2004).
1.3.3 Approximately 14 million seabirds, with
5.5 million nesting annually in the NWHI, rely on the coral reef ecosystem
for food and other habitat needs (Naughton and Flint 2004). In turn,
the ecosystem is dependent on these birds’ role in the high
relative productivity and diversity of the NWHI. Nutrient-rich defecation
(guano) deposited by the birds on the islands and nearshore waters
– which subsequently is dissolved and provides significant levels
of nitrogen to the ecosystem – is thought to stimulate the prolific
growths of algae found around the islands. When high levels of algal
growth are combined with significant wave action, such as at La Perouse
Pinnacle at French Frigate Shoals, this creates favourable conditions
for the growth of other species (Maragos and Gulko 2002).
1.3.4 The ecological processes of the NWHI depend
on more than just its coral reefs. Beyond the banks and steep slopes,
between 1,640 and 14,000 feet, the ocean floor levels out at sea bottom
which contains distinct, rich habitat (Press and Siever 1986; Benoit-Bird
et al. 2001). This habitat is linked to the coral reef ecosystem by
a dense assemblage of small fish, shrimp, and squid that migrate from
the ocean depths to near the surface in regular patterns and serve
as an important food resource for many animals, including spinner
dolphins, bottom fish, tunas, and billfish (Benoit-Bird et al. 2001).
The importance of offshore and deepwater habitat is also evidenced
by the movements and diets of Hawaiian monk seals. Although part of
the seals’ diet comes from shallow-water coral reef fish, the
seals are known to travel over one hundred miles between islands and
dive to depths of greater than 900 feet when foraging for deepwater
prey, mainly bottom fish, which make up the primary part of their
diet (Henderson 2001; TenBruggencate 2006). Each of these habitats
is essential to the other, and the loss of one affects the operation
of all the others throughout the system. Accordingly, an impact on
one part of the system can threaten the entire ecosystem as well as
the diversity of species that depend on the area.