Seagrass, Algae, and Coral Reefs Shallow Seas Seagrass, Algae, and Coral Reefs

Seagrass vs. Algae Seagrasses Algae Found in the plant kingdom Have actual roots below the mud, transport tubes (xylem and phloem) for transporting nutrients and water around the plant Algae Found in Kingdom Protista Can be multicellular or unicellular Have structures to attach them to surfaces, but no underground root systems No transport tubes

Seagrass Beds General Characteristics The only flowering plants that live entirely in the sea

Growth of Seagrasses Grow best in shallow, sandy areas with clear water, like lagoons or enclosed bays Thrive in tropics Tolerant of varying salinity levels

Structure Roots – (unlike seaweeds) absorb nutrients from the sediments / mud and anchor the plant This recycles nutrients that would otherwise be locked up below the surface Underground Roots are intertwined, wrapped around each other This helps Stabilize the sand and sediment of the ocean bottom Protects from erosion Encourages buildup of sediments helps other species to gain a foothold in the shifting sand.

Structure Leaves Flower Perform photosynthesis, providing the plant with a source of glucose Flower Structure for reproduction

Seagrass Bed Communities Seagrass beds are highly complex Attracts a high biodiversity of species that live and rely on them

Biodiversity in Seagrass Beds Seaweeds (algae) grow on the leaves or fronds of the seagrasses

Biodiversity in Seagrass Beds Sedentary organisms- live on the grasses Ascidians Hydroids (sea lace) bryozoans

Camoflauge in Seagrass Beds Some animals live in seagrass beds their entire life, and have evolved to be adapted for it Seahorses & seadragons crabs

Seagrass Beds as Nurseries Some species use seagrass beds to raise their young

Seagrass Beds as Food Sources Some animals eat the seagrass plants dugongs manatees Sea urchins

Algae – Kelp Forests

General Characteristics Kelp refers to a type of brown seaweed Kelp forests grow best in cold, nutrient-rich waters, extending into polar regions

Kelp Growth Live attached to rocks in semi-shallow water, top edge of some kelp beds can be seen at the lowest tides. Grow densely on rocks and rocky slopes down to around 30-70 feet deep Need light for photosynthesis Can grow deeper in clearer water, but sparsely due to less light for photosynthesis

Kelp Structure: multilayered environment that different organisms live on Holdfast- Instead of roots, kelp has a root-like anchor that helps keep the kelp to the rocky bottom Frond- palm like leaf structure, One stipe, with pneumatocysts (gas bladder) and blades, make up a single frond. Blade- like a leaf. It extends horizontally in the water to get sunlight for photosynthesis Gas Bladder- floats on the stem; Gas-filled sections of the stipe, called pneumatocysts, help keep the kelp upright and oriented towards the surface Stipe-stem or trunk, transports nutrients to the holdfast below and the blades above.

Kelp Communities: within the kelp forests the water is calmer Supports rich marine communities Used mostly as shelter Only about 10% of kelp is eaten directly The rest enters the food chain as detritus or dissolved organic matter.

Holdfast Habitats Small animals hide from predators in the small spaces of the holdfast Sea urchins and limpets found grazing on the ocean bottom, on the red seaweeds growing on the kelp in deeper water

Frond Habitats Actively growing kelp Fronds are coated in slime for protection from being eaten as growth slows later in the season, the fronds may become covered with bryozoans, hydroids, and tube worms. Some species grow or live on the fronds Reduce the light reaching the fronds for photosynthesis Kelp shed their fronds to get rid of the pests sea floor beneath the kelp may be covered with marine growth, or relatively barren if heavily grazed by sea urchins Bryozoans Hydroids Tube worms

Seagrass and Kelp Nurseries Seagrass beds and kelp forests are important refuges for young fish that need to hide from predators until they reach maturity. Many fish do not live among seagrasses or kelps as adults, but come into these habitats to spawn, giving their young a greater chance at survival.

Seagrass and Kelp Nurseries Small fish find an abundance of small prey in the form of tiny worms, crustaceans, and mollusks among the seagrasses and in the sediment beneath. These young fish are often camouflaged in shades of green and brown to avoid detection.

Seagrass and Kelp Nurseries Some herbivorous fish from surrounding reefs come into seagrass beds only at night. Seagrass beds are important nurseries for some commercial invertebrates, including shrimp and cuttlefish Many young fish are camouflaged for this environment, and look completely different than the adults