Energy in Marine Ecosystems: Marine Food Chains Begins with the primary producers They are autotrophs (‘self’-‘feeders’) - Organism capable of making organic compounds, –Photoautotrophs, such as plants, use solar energy to help make these compounds in a process known as photosynthesis. Primary producers are consumed by primary consumers –Primary consumers, are heterotrophs (‘other’- ‘feeders’)- Organisms incapable of making organic compounds from inorganic material, they obtain their nutrition by consuming autotrophs and derive energy through respiration. Primary consumers are consumed by secondary consumers, a.k.a. tertiary producers. And so on…Food chains vary in length.

© 2002 Brooks/Cole, a division of Thomson Learning, Inc. Capture and Flow of Energy The flow of energy through living systems.

© 2002 Brooks/Cole, a division of Thomson Learning, Inc. The Cycling of Matter The cycling of matter through living systems.

Food Chains Food Chain- Energy and matter move from one organism to another as each eats a lower member and, in turn, is eaten by a higher member

Decomposers Organic matter not eaten by a higher-level consumer is decomposed by decomposers –Break down non-living organic matter into its original components: carbon dioxide, water and nutrients. When this matter dissolves in the water and is known as dissolved organic matter (DOM). Decomposers are important to the food web because they regenerate nutrients, which are then used by the autotrophs. Ex: Fungi, Bacteria

Detritus Dead organic matter in solid form, such as decaying seaweeds, is called detritus. –Detritus is an important energy pathway in marine ecosystems because many organisms feed on it, especially those that live below the euphotic zone. –Marine Detritivores- Worms, sea cucumbers, clams

Figure 10.11

Trophic Levels Each ‘link’ in the food chain is called a trophic level. (troph means food) –1 st =Primary Producer Ex: plants, algae –2 nd = Primary Consumer Ex: Grazer, herbivores –3 rd = Secondary Consumer Ex: Carnivores –4 th = Tertiary Consumer, etc… At each level, detrivores and decomposers are turning biomass into nutrients

Because organisms consume at various trophic levels, it is really more like a web, not a chain. Food Web

Figure 10.13

© 2002 Brooks/Cole, a division of Thomson Learning, Inc. Antarctic Ocean Food Web Diatoms, and other primary producers, convert the energy from the sun into food used by the rest of the oceanic community.

Ecological Efficiency and Ecological Pyramids About 90% of biomass is lost when transferred from between trophic levels –Ecological efficiency= 10% As trophic levels increase, biomass decreases –Why there are more squirrels than wolves in the world

Ecological Pyramid 2° Consumers 3° Cons g Biomass 100 g 10 g 1 g Primary Producers Primary Consumers

Figure 10.14b

Figure 10.14a

© 2002 Brooks/Cole, a division of Thomson Learning, Inc. Feeding Relationships

Figure 15.02

Pelagic Primary Producers Phytoplankton- Diatoms

Pelagic Primary Consumer

Pelagic Primary Consumer Larvacean

Holoplankton

Holoplankton- Jelly

Meroplankton

Nekton

© 2002 Brooks/Cole, a division of Thomson Learning, Inc. Primary Productivity Oceanic productivity is measured in gC/ m 2 /yr.

Figure 10.15

Figure 10.16

Global Primary Production

Carbon Cycle

Nitrogen Cycle