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).

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

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

c. benthos - bottom dwellers (1) epifauna - walk on the substrate ex. crabs infauna - live in the substrate ex. worms d. demersal - hover, swim or rest ex. flounder, skate, rays e. sessile - attached ex. barnacles, sponges NOAA

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.

a. producers - phytoplankton, start the food chains 3. Communities - 2 or more populations occupying different niches in the same habitat. photo credit: Florida Keys National Marine Sanctuary 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

Communities age in a process called Biological Succession. Dr. James P. McVey, NOAA Sea Grant Program 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

Ex: coral reefs, polar seas DCI: LS2.A LS2.B LS2.C SEP : 2,4,8 CCC: 1,2,4,5,6,7 DCI: LS2.A LS2.B LS2.C SEP : 2,4,8 CCC: 1,2,4,5,6,7 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

Ecosystem Energy In ecosystems, energy is cycled through these niches: autotrophs - produce food by photosynthesis heterotrophs - consume autotrophs and other heterotrophs decomposers - rearrange organic materials into nutrients for autotrophs The amount of energy available to support life or the largest population that can be sustained by the available resources is called the carrying capacity.

Food chains represent the steps in transferring energy through the ecosystem. Complex and integrated food chains are called food webs. A keystone species is the critical biomass in an ecosystem because the food web is built around that particular organism. Energy can be represented by trophic pyramids that compare the number of organisms in a population, or the weight (biomass) of organisms, or the productivity (energy calories).

Generally, only 10% of the energy is passed on to the next higher level. Why does the amount of energy change if energy is never created or destroyed? 1. It can be converted into unusable forms such as heat or for an organisms’ respiration, metabolism, and predation. 2. Not all parts of an organism have food value or provide calories. ex: bones, scales USDA

The amount of energy available is calculated as net productivity or primary productivity. Primary productivity of the ocean is 22-28 billion tons of carbohydrates (mostly glucose). Gross productivity - respiration = net productivity given in units of g/m2/yr. Respiration is the amount of energy used at each level to maintain life (estimated at 90% of the available calories). If one trophic level has 100,000 calories available, only 10,000 can potentially be transferred to the next trophic level.

phytoplankton krill baleen whale The more levels in the ecosystem pyramid the less energy is available in a useable form at the next higher level. Shorter food chains are more efficient. The reason the ocean can support the tremendous expense of endothermic (warm-blooded) mammals is because they eat low on the food chain.