Aquatic Ecology - Content Study Guide

How are terrestrial and aquatic ecosystems different in terms of primary producers?

• Primary production 

  • aquatic ecosystems: microscopic phytoplankton (their size allows for floatation and drift. Rooted plants only have a minor role in nutrient production.

  • terrestrial ecosystems: large visible forms like grasses and trees that are rooted firmly in substrate 

How are terrestrial and aquatic ecosystems different in terms of structural support?

• Aquatic Ecosystems: density of water provides structural support for aquatic organisms 

• Terrestrial Ecosystems: plants require roots for anchoring and trunks for support 

  • meaning they need production of carbohydrates like cellulose and lignin to promote the strength and rigidity (aquatic plants do not need this) 

  • Terrestrial animals also need to invest more in skeletal support 

How do terrestrial and aquatic ecosystems differ in nutritional content? 

• Aquatic ecosystems: phytoplankton are primary composed of protein

  • Little of this production enters the decomposer cycle  

• Terrestrial/transitional: primary production is in the form of inedible/indigestible components (cellulose and lignin contained in bark, trunks, roots). *Only 5-15% is eaten by herbivores 

  • most of the indigestible material enters the food chain via the decomposition cycle.

How do terrestrial and aquatic ecosystems differ in their autotroph-heterotroph ratio?

• Aquatic ecosystems: phytoplankton are very small and have high protein content —> they are very efficient producers 

  • Because phytoplankton are so small, the aquatic ecosystem food pyramid is flipped

• In terrestrial ecosystems the numbers, biomass and energy levels are always higher for autotrophs and heterotrophs (more plants than animals!)

How do terrestrial and aquatic ecosystems differ in their productivity?

• Primary production (Kcal of energy captured per square meter) in aquatic ecosystems is lower than on terrestrial ecosystems

• Transitional areas (including marshes) are as productive if not more productive than terrestrial ecosystems

How do terrestrial and aquatic ecosystems differ in their production to biomass ratio? 

• Aquatic ecosystems: phytoplankton has low biomass but they are extremely fast growing 

  • high production to biomass ratio 

• Terrestrial ecosystems: have high biomass but are slow growing and long lived. 

  • lots of the primary production is used to maintain respiration and nutrition of that biomass 

  • Terrestrial gestation has lower production to biomass ratio 

How do terrestrial and aquatic ecosystems differ in their production efficiency and energy requirements?

• Aquatic: most animals are cold blooded with lower energy requirements, are buoyant and use little energy in locomotion instead the energy is put toward growth and reproduction 

  • production efficiency is 10x higher in aquatic cold blooded animals, this means that aquatic systems have a higher secondary production compared to terrestrial systems 

• Terrestrial:  most animals are warm blooded,

How do aquatic and terrestrial systems differ in their dominant species? 

• Aquatic ecosystems: dominated by animals 

• Terrestrial ecosystems: dominated by plants

  • Ex. Ocean contributes only 35% of the world plant production, but it accounts for nearly 80% of animal production

How do aquatic and terrestrial ecosystems differ in their changes to physical/chemical environment? 

• water is more constant that air, terrestrial ecosystems change significantly throughout the year and day

  • Ex. Long Island can fluctuate 80C in a day, where as marine temps may only fluctuate 27C

How to aquatic and terrestrial ecosystems differ in their nutritional sources? 

• Terrestrial: organic food is located in living organisms 

  • terrestrial plants absorb nutrients through their roots, but terrestrial animals cannot absorb nutrients directly from the air/soil

• Aquatic: every gram of living organisms is 10 grams of dead organic matter and 100 grams of dissolve organic matter 

  • most plants and animals absorb nutrients directly from the water

  • Phytoplankton have high surface to volume ratio which promotes uptake of nutrients directly through the cell wall

How do aquatic vs terrestrial systems differ in animal/protozoan biodiversity?

• of the 37 animal phyla, 36 are mostly aquatic or marine

• nearly 90% of terrestrial fauna is insects (which are absent from marine waters)