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 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 2002 Brooks Cole a division of Thomson Learning Inc 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 Figure 10 11 Trophic Levels Each link in the food chain is called a trophic level troph means food 1st Primary Producer Ex plants algae 2nd Primary Consumer Ex Grazer herbivores 3rd Secondary Consumer Ex Carnivores 4th Tertiary Consumer etc At each level detrivores and decomposers are turning biomass into nutrients Food Web Because organisms consume at various trophic levels it is really more like a web not a chain Figure 10 13 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 2002 Brooks Cole a division of Thomson Learning Inc 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 1g 2 10 g g Bi oma o C n r a m Pri 100 g 1000 3 ns o C rs e sum on C y ar m Pri ss rs e su m ro P y r e c du s Figure 10 14b Figure 10 14a Feeding Relationships 2002 Brooks Cole a division of Thomson Learning Inc Figure 15 02 Pelagic Primary Producers Phytoplankton Diatoms Pelagic Primary Consumer Pelagic Primary Consumer Larvacean Holoplankton Holoplankton Jelly Meroplankton Nekton Primary Productivity Oceanic productivity is measured in gC m2 yr 2002 Brooks Cole a division of Thomson Learning Inc Global Primary Production Global Productivity Figure 15 25b Continental Shelf Richest part of the ocean with the world s most important fishing grounds Extends from the subtidal to the shelf break the outer edge of the continental shelf where depths drastically increase The average depth is around 150 m Varies in width from less than 1 km to over 750 km Important characteristics to organisms Relatively shallow Temps vary more here than in the deeper ocean Affected by waves currents and storms Tides can cause particularly strong tidal currents Wind waves can affect to 200m Turbulence prevents stratification Therefore more productive than the open ocean Close to land Rivers discharge into this zone of the ocean bringing nutrients phytoplankton and sediment These combine to make the water murkier than farther offshore Murkier water means light doesn t penetrate as deeply reducing the euphotic zone depth Figure 13 05 Soft Bottom Organisms The Epipelagic The pelagic realm of the ocean describes the vast open ocean The epipelagic realm is the upper part of this environment Depths only to about 200m Corresponds to the depth of the euphotic zone Euphotic depth the depth below which where there is no longer enough light for organisms to grow Divided into coastal or neritic waters that lie over the continental shelf and oceanic waters Epipelagic Food Web Seasonal Productivity Tropics Seasonal Productivity Temperate Seasonal Productivity Polar CO 12 Figure 12 01 Figure 12 11 Figure 12 12 Figure 12 13a Figure 12 13b Figure 12 14 Figure 11 19b Figure 11 25b Figure 11 33 Figure 11 34
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