Читать книгу Oceans For Dummies - Joseph Kraynak - Страница 80

When you start to need some sort of flotation device (or a boat) to keep your head above water, you’re in the neritic zone (also known as the sublittoral zone). This area starts at the low tide mark and continues to the edge of the continental shelf in the ocean — about 200 meters (660 feet) deep. While that may sound really deep, it’s relatively shallow compared to how deep it gets out in the open ocean, which is much, much, much deeper.

Biodiversity is at its peak in the neritic zone, and no wonder — everyone wants to live here! Virtually every marine plant and thousands of coastal animal species (vertebrates and invertebrates) call this zone home. Consequently, the neritic zone is where 90 percent of all marine life resides. Diverse ecosystems flourish in and around coral reefs, seagrass beds, and kelp forests, all of which rely on sunlight-powered photosynthesis.

Why is it such a popular place? Well, conditions in the neritic zone are ideal for supporting diverse marine communities — the presence of sunlight throughout the zone; moderate, stable temperatures, pressures, and salinity; plenty of oxygen and carbon dioxide; and an abundance of nutrients that make their way from the land into the ocean (which under normal circumstances is good but can be bad when it’s too much).

In fact, the neritic zone is such a pleasant place, it’s also a popular hangout for sea creatures that move between deeper open ocean and shallow coastal waters, such as some sharks, turtles, and dolphins. And that’s not all — common visitors include those that feed in coastal waters but can also haul out onto land, such as some marine reptiles, pinnipeds (seals, sea lions, walruses), and penguins.

Even though the neritic zone accounts for only about 10 percent of the ocean, it produces roughly 90 percent of all the fish and shellfish we harvest, making it very valuable for us humans too.