Standing on a hill overlooking Elkhorn Slough NERR, an observer is able to see most of the seven mile length of the estuary as it winds from the open ocean of Monterey Bay to the small seasonal creeks at the upper end of the slough. Sea otters, harbor seals, pelicans and egrets are some of the animals visible from this vantage point. Read more
After a short walk down the hill, a closer inspection of the slough reveals hundreds of small birds feeding in the mudflats now exposed at low tide. There are crabs scurrying along the muddy edge of the salt marsh and schools of top smelt rippling the water's surface. Brown Pelicans and Caspian Terns hover overhead, and then drop from the air to grab the small, surface feeding fish. The sounds and smells of life in the slough are everywhere.
The shallow, protected, nutrient rich waters of the estuary provide an important nursery for animals as different as the fat innkeeper worms and the leopard sharks that feed on them, the shy and curious harbor seals, baseball-sized moon snails, and ghost shrimp. These large animals are fun to watch. They delight and fascinate us with their behavior and sometimes cause us to wonder what their lives are like and how they survive. But what we can't see in the water, and probably don't think too much about, is even more important to the life of the estuary. What we can't see are the plankton, and everything depends upon them.
Plankton are found in almost any of Earth's many bodies of water. They exist in vast, unimaginably large numbers and form the biological base of aquatic food webs. Not only that, but the plant-like phytoplankton are responsible for most of the transfer of carbon dioxide from the atmosphere to the ocean, a process known as the carbon cycle, and produce more than 60% of the oxygen in the air we breathe.