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Marine Biology. Study of living organisms in the ocean LIFE = ? Ability to capture, store, and transmit energy Ability to reproduce Ability to adapt to their environment NASA: A self-sustained chemical system capable of Darwinian evolution. Evolution.
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Marine Biology • Study of living organisms in the ocean • LIFE = ? • Ability to capture, store, and transmit energy • Ability to reproduce • Ability to adapt to their environment • NASA: A self-sustained chemical system capable of Darwinian evolution
Evolution • Explains the unity and diversity of life • Charles Darwin and Alfred Wallace • Definition? • Change • Mechanism = natural selection • reproduction, mutation/variation, selection
Land is more variable- leads to more species • Likely between 6-12 million species total • Likely about 1 million marine species • 2000 new marine species discovered each year
Classifying marine organisms • Pelagic • Plankton • Nekton • Benthic
Living in the Ocean: Advantage= Water everywhere
Living in the Ocean: Disadvantage= Hard to move
Living in the Ocean: Disadvantage= Hard to move
Common Problem: Surface Area to Volume Ratios
Primary Producers • aka autotrophs • Organisms that can capture solar energy and convert it to chemical energy by building organic compounds • Photosynthesis
Primary Producers • Others use chemosynthesis • Much less common • Use the oxidation of inorganic compounds as energy source, • ex: bacteria use hydrogen sulfide at hydrothermal vents
Cellular Respiration • Opposite of photosynthesis • Breakdown of food • All organisms
Consumers • aka heterotrophs • Must consume (eat) other organisms
Consumers • Primary consumers • Eat producers • Secondary Consumers • Eat primary consumers • These all are Trophic Levels
Food webs • Complex representation of who eats who
Primary Productivity • Refers to how active the producers are • grams of Carbon bound into organic material per square meter per year (gC/m2/y)
Only 10% of “food” gets transferred to the next trophic level
Ocean’s Primary Producers • Algae – in Kingdom Protista • Have chlorophyll but no vessels to conduct fluids • Unicellular = phytoplankton – pelagic • Multicellular = seaweed – benthic • Plants • Angiosperms = flowering plants
The Pelagic Zone • Pelagic organisms are suspended in the water • Plankton = drifters • Phytoplankton= unicellular photosynthetic algae • Zooplankton = “animal” plankton • Nekton = swimmers
Phytoplankton • 95% of ocean’s primary productivity • Mostly Single-celled organisms • Diatoms & Dinoflagellates
Diatoms • Dominant (>5600 species) • Silica shell – two valves • Produce large portion of O2 in ocean and atmosphere
Dinoflagellates • Mostly autotrophs • Most are free living (except zooxanthellae) • Two whip-like flagella • “Red tides” or HABs (Harmful Algal Blooms)
Phytoplankton Distribution • Depends on: • light availability • nutrient concentration • Varies with: • Depth, Proximity to land, Location on the earth
Phytoplankton Distribution • Compensation Depth • Where rate of photosynthesis = rate of respiration • Below this phytoplankton will die
Phytoplankton Distribution • Higher near coast • Runoff • upwelling
Phytoplankton Distribution Varies across the globe – How?
Phytoplankton Distribution • Tropics • Low • Nutrients trapped below thermocline
Phytoplankton Distribution • Poles • Mostly Low (except for summer peak) • Insufficient light
Phytoplankton Distribution • Temperate Regions • Highest overall • sufficient light & nutrients • Spring Peak • Increasing sunlight • Fall Peak • Increasing mixing of nutrients
Zooplankton • Animal plankton – many different types • Heterotrophic – primary consumers • Based on the phytoplankon abundance graph…how would you expect zooplankton abundance to vary?
Zooplankton • Major types – • Radiolarians • Foraminifers • Copepods • Krill
Zooplankton • Holoplankton • Spend their entire life in plankton • Major types – • Radiolarians • Foraminifers • Copepods • Krill • Jellyfish (cnidarians) and comb jellies (ctenophores)
Figure 14.3: Radiolarians Single-celled; Hard shell made of silica