Interactions

Biotic and abiotic interactions shape, determine and define the success (or lack there of) for all habitat.

Cocos Island and the Gemelas Seamounts

In September 2009, National Geographic Fellow Enric Sala, National Geographic Explorer-in-Residence Sylvia Earle, and a team of leading marine scientists from Central America and across the globe gathered together in Costa Rica. Destination: Cocos Island—Isla del Coco, ringed by some of the most shark-rich waters anywhere—and the submerged and all-but-unexplored summits of the Gemelas (“Twin Sisters”) Seamounts.

The team worked with local marine scientists and conservation organizations to document these aquatic ecosystems. The data, they hope, will help to establish new scientific baselines for intact—and critically important—environments.

While Cocos has helped define the world’s image of an untouched island paradise for centuries, the Gemelas Seamounts have lurked, mostly unseen and unknown, beneath hundreds of feet of seawater. But marine creatures know them as fertile and important waypoints on their wanderings. These rich feeding grounds may be critical to the survival of many of the migratory predators that pass through them.

This could all be endangered through intentional and unintentional interactions with coastal environments.

As climate change has warmed the Earth, oceans have responded more slowly than land environments. But scientific research is finding that marine ecosystems can be far more sensitive to even the most modest temperature change.

Global warming caused by human activities that emit heat-trapping carbon dioxide has raised the average global temperature by about 1°F (0.6°C) over the past century. In the oceans, this change has only been about 0.18°F (0.1°C). This warming has occurred from the surface to a depth of about 2,300 feet (700 meters), where most marine life thrives.

Perhaps the ocean organism most vulnerable to temperature change is coral. There is evidence that reefs will bleach (eject their symbiotic algae) at even a slight persistent temperature rise. Bleaching slows coral growth, makes them susceptible to disease, and can lead to large-scale reef die-off.

Other organisms affected by temperature change include krill, an extremely important link at the base of the food chain. Research has shown that krill reproduce in significantly smaller numbers when ocean temperatures rise. This can have a cascading effect by disrupting the life cycle of krill eaters, such as penguins and seals—which in turn causes food shortages for higher predators.

Higher Sea Levels

When water heats up, it expands. Thus, the most readily apparent consequence of higher sea temperatures is a rapid rise in sea level. Sea level rise causes inundation of coastal habitats for humans as well as plants and animals, shoreline erosion, and more powerful storm surges that can devastate low-lying areas.

Stronger Storms

Many weather experts say we are already seeing the effects of higher ocean temperatures in the for m of stronger and more frequent tropical storms and hurricanes/cyclones. Warmer surface water dissipates more readily into vapor, making it easier for small ocean storms to escalate into larger, more powerful systems.

These stronger storms can increase damage to human structures when they make landfall. They can also harm marine ecosystems like coral reefs and kelp forests. And an increase in storm frequency means less time for these sensitive habitats to recover.









Try a tide simulator don't forget to click on the neap/spring identifier.

Two oceanic bulges—one on the side of the Earth facing the moon and the other on the side opposite from the moon—move in relation to our satellite as it orbits us, causing in most places two high tides a day as our planet rotates on its axis. The moon's gravity pulls the ocean toward itself to create the near-side bulge, but this doesn't account for the bulge on the far side.

Here, follow a step-through animation that explains why water rises on the side of the Earth away from the moon. Tides also make a difference in our interactions on a quite regular schedule..

(More cool stuff )

Why do the biggest tides happen when the moon is new and full?

Although tides are affected mainly by the moon's gravity, gravity from the sun also pulls on the oceans. In fact, the tidal force of the sun is almost half ( 46%) that of the moon. When the moon, sun, and Earth line up, we see either a full moon (if we're between the moon and the sun) or a new moon (if the moon is between us and the sun). At these times, the gravitational forces of the sun and moon work together, increasing the overall pull on the Earth and its oceans.

Why is the tide cycle 24 hours 50 minutes long instead of just 24 hours long?

You might think that, because the length of the tide cycle is determined by the Earth's rotation, the tide cycle should be 24 hours long. The reason it's longer is that, during a 24-hour period, the moon travels about 12 degrees of its 360-degree orbit. The extra 50 minutes is how long it takes any spot on the Earth to "catch up" to the moon's new position.





So... what do you think?

Questions?