1

MARINE ECOLOGY TERMS

Ecology - study of the relationship of living organisms (biota) to the environment (abiotic or non-living part)

Each organism is structurally, chemically or behavioral adapted for a particular habitat (place) and occupies a particular niche (job).

2

Major marine habitats are divided into 2 groups:

1. Pelagic Zone - photic zone containing plankton (floaters) and nekton (swimmers)

a. neritic - coastal areas

b. oceanic - open water

2. Benthic Zone - substrate on the margins or basins

a. aphotic - 90% dark area of open water

b. abyssal - deep bottom of the ocean floor

3

These habitats are occupied by five levels of biota:

1. Individual - ONE plant or animal of a species

a. plankton - organisms that can not make a forward motion against a current

(1) phytoplankton - photosynthetic primary producers

(2) zooplankton - primary consumers

b. nekton: swimming animals ex. fish, mammals, birds, reptiles

4

c. benthos - bottom dwellers

(2) infauna - live in the substrateex. worms

(1) epifauna - walk on the substrateex. crabs

d. demersal - hover, swim or rest ex. flounder, skate, rays

e. sessile - attached ex. barnacles, sponges

NOAA

5

2. Populations - 2 or more individuals of the same species who must compete for mates, food, light, and space because they occupy the same niche and habitat.

DNA studies are used to identify which individuals are part of a population. Population density is the number of individuals divided by the size of the habitat.

Density is affected by geography, seasonal factors, pollution, and birth-death ratio based on the number of adults.

6

3. Communities - 2 or more populations occupying different niches in the same habitat.

Community living has an advantage by reducing competition, increasing variety and diversity. The general niches are:

a. producers - phytoplankton, start the food chains

b. consumers – eat others - herbivores, carnivores, omnivores

c. decomposers - scavengers, break down organic compounds into nutrients for producers

photo credit: Florida Keys National Marine Sanctuary

7

Communities age in a process called Biological Succession.

a. Pioneer - first populations move into a habitat such as the polychaete worm pictured here.

b. Juvenile - young populations; simple food chains

c. Mature - older communities with complex food webs,stable populations are those where natality = mortality

Dr. James P. McVey, NOAA Sea Grant Program

8

4. Ecosystems have 2 or more communities whose life style is related to a unique habitat.Ex: coral reefs, polar seas

Changes in the components will have unpredictable effects, but ecosystems have remarkable ways of restoration.

5. The biosphere is composed of many ecosystems, exhibiting great diversity, that are related by the interdependence of living things.

NOAA