Algae

The Chesapeake Bay and its tidal tributaries are home to dozens of species of algae. Along with certain bacteria, they release oxygen and, as primary producers, form the foundation of the Bay’s food web.

Soaking up sunlight and taking in nutrients from the water, algae comprise the broadest base of Chesapeake Bay’s food web. Non-vascular, and lacking traditional leaf-stem-root systems, these plants range from microscopic phytoplankton to highly visible green algae such as Ulva (sea lettuce).

As food for grazing plankton, fish, and their predators, algae are the force behind all life in the Bay. Without them there’d be no blue crabs, no striped bass, no seabirds. In turn, algae need sunlight, carbon dioxide, and nutrients such as nitrogen and phosphorus to carry out their life’s work: producing oxygen and glucose through photosynthesis.

In early spring, increases in sunlight and nutrients fuel blooms of phytoplankton — including photosynthesizing dinoflagellates and diatoms. These single-celled organisms are often classified as algae since many — though not all — contain chloroplasts, the chlorophyll-containing cell organelle that spurs photosynthesis in all plants.

Dinoflagellates have whip-like flagella that allow them to move through the water and hunt prey — about half of all dinoflagellates must feed on other organisms for nourishment (and are therefore called heterotrophic).

Conversely, almost all diatoms are capable of making their own food through photosynthesis (and are therefore called autotrophic). Unlike dinoflagellates, they float in the water with no means of propulsion. Encased by a silica wall that resembles glass, they take on beautiful and varied shapes visible only under a microscope.

Scientists study the relative abundance of dinoflagellates, diatoms, and other algae in the Chesapeake to glean insight into the overall health and productivity of the Bay.

When algae bloom in over-abundance due to excess nutrients, they can throw the Bay out of balance, robbing bottom waters of life-sustaining oxygen. Some algae can even be toxic leading to both environmental and human health issues.