The Subtidal 1

The Subtidal

Life on the Continental Shelf

The Subtidal 2

The Continental Shelf

The Subtidal 3

Sampling the Benthic Habitat

•Bottom trawls•Grabs •Dredges

The Subtidal 4

The Continental Shelf What we know about this community:

Very few species are dominant and constitute most of the biomass

Parallel bottom communities Many analogies can be drawn to similar areas

Different species but are ecologically equivalent These communities are extremely stable over time Animals are distributed in a patchy manner and

organisms occur at various depths in the substrate

The Subtidal 5

Abiotic Factors Species distribution varies from the

poles to the tropics

Shallow water is affected by currents and wave action

Nutrients are not limiting

The Subtidal 6

Soft-bottom Subtidal Communities

This substrate dominates the worlds continental shelves Animals are distributed in this

community based on sediment particle size, stability of the sediment, light and temperature

Organisms usually occur in patches, due to planktonic settlement

Metamorphose and “tasting settlement sites”

The Subtidal 7

Unvegetated Soft-bottom Communities

Notable is absence of large plants and algae There is little primary

production so the filter feeders and suspension feeders rely on detritus brought from estuaries

Deposit feeders and bacteria dominate fine sediments due to high organic content

The Subtidal 8

Seagrass beds Areas that are

carpeted by flowering plants

They develop best in sheltered shallow areas along the coast

Eel grass is our most common representative

The Subtidal 9

Seagrasses Thick mats of eel grass

provide lots of habitat for animals to hide

By stabilizing the sediment it decreases the turbidity Dead sea grasses

provide lots of detritus that benefit suspension, deposit and filter feeders

The Subtidal 10

Sea Grass Food Web

The Subtidal 11

Rocky subtidal bottoms and Kelp Forests

Animals that are present have the same characteristics as those of the rocky intertidal

Kelp is a macroalgae which can reach amazing sizes

The Subtidal 12

Kelp and Kelp Forests