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Reefs with relatively high biodiversity, such as those

Anotherimportantconsiderationistherelativelynarrow

in the Indo-Pacific, have generally shown greater

area to which some marine species, particularly reef

resilience to disturbances than have reefs with

organisms, are restricted. Corals, for example, have

fewer species, such as those in the Caribbean1. A

quite specific light and temperature requirements.

Range-restricted organisms are more vulnerable to

similar pattern has been observed recently on the

perturbations and extinction than are more wide-

Mesoamerican Reef, where preliminary 2006 survey

ranging organisms.

results indicate a greater resistance to climate change

and bleaching among the more diverse inshore reefs.

Today, loss of marine biological diversity is occurring at

Other factors -- ones unrelated to biodiversity -- may

an alarming rate. Despite the ecological and economic

also contribute to differences in resilience.

significance of many species, marine biodiversity is

significantly threatened by overexploitation, pollution,

When planning to protect biodiversity, it is important

habitat alteration and global climate change. Scientists

to remember that marine ecosystems are inherently

have documented at least one recent MAR marine

different  from  their  terrestrial  counterparts.

extinction. The Caribbean monk seal, once vigorously

Conservation lessons learned on land cannot be

hunted for its blubber, has not been officially sighted

simply transferred to marine areas.

since 19522.

Marine ecosystems are generally open systems, with

larvae, juveniles and adults often moving from one

Maintaining high species diversity within key functional

habitat to another at different life stages. Dispersal

groups (such as coral and fishes) and preventing further

of many free-floating marine larvae occurs over very

extinctions are important elements of preserving reef

large areas, and marine larval distributions may

ecosystem health3.

demonstrate greater variability than would be typical

Indicators selected to track biodiversity are:

for terrestrial species. For example, preliminary

models of connectivity between fish spawning sites

S1

Coral Diversity

and predicted settlement reefs showed reefs in

Mexico and Northern Belize receiving larvae from

S2

Fish Diversity

Cuba in some years, but not in others, due to the high

variability of weather and oceanographic patterns,

S3

Focal Species Abundance

including eddy formation and duration1.b.. Activities

that act as barriers (e.g., habitat fragmentation or

disruption of larval flow) can reduce genetic diversity

and overall ecosystem function. In the MAR ecoregion,

the destruction of mangrove nursery areas is a

particular concern.

S

Rachel T. Graham

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