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2.2.2 Abiotic factors in Marine Ecosystems. Marine Ecosystems. Limiting Factors. Too much or too little of a single physical factor can adversely affect the function of an organism.
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Limiting Factors • Too much or too little of a single physical factor can adversely affect the function of an organism. • Limiting factors are physical or biological necessities whose presence or absence in inappropriate amounts limits the normal action of the organism.
Light is needed for photosynthesis and vision. • Blue light penetrates deepest. • Limited also by particles in the water.
Temperature influences the metabolic rate, the rate at which reactions proceed within an organism.
Most marine organisms are ECTOTHERMIC having an internal temperature that stays very close to that of their surroundings. • A few complex animals (mammals & birds) are ENDOTHERMIC, meaning they maintain a stable internal temperature. • Ocean temperature varies in both depth and latitude. • Ocean temperatures vary less than on land.
Salinity greatly affect cell membranes and protein structure. • Disrupts cells osmotic pressure. • Varies because of rainfall, evaporation and runoff from land.
Dissolved Gases are necessary for photosynthesis and respiration. • CO2 dissolves more easily in water than O2. • CO2 is more abundant in deep waters than surface water. • O2 decrease dramatically where light penetration decreases.
Pressure from the layers of water above. • Increases with increasing depth. • Pressure affects buoyancy (ability to float). • To counteract the mass of heavy muscles and bone, many swimming fishes have gas-filled bladders. • Deep-sea fish don’t have gas bladders, but light bones and oily watery flesh.
Marine Zones • Areas of homogeneous physical features. • Usually based on light, temperature, salinity, depth, latitude, behavior and/or water density.
By light Photic zone sunlit layer of water at the ocean’s surface. • Upper zone is called the Euphotic zone and is where the rate of photosynthesis is high. • Lower zone is called Disphotic zone and is where organisms can see, but there is sufficient light for photosynthesis. Aphotic zone where no light penetrates.
By Location Pelagic zone between water and ocean bottom. a. Neritic zone = near shore over the continental shelf
b. Oceanic zone = deep-water beyond the continental shelf. i. Epipelagic = photic zone of the ocean. ii. Mesopelagic = middle ocean waters. iii. Bathypelagic = ocean floor. iv. Abyssopelagic = deep-ocean trenches.
