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
•Likely between 6-12 million species total•Likely about 1 million marine species•2000 new marine species discovered each year
Classifying marine organisms• Pelagic (in water)
– Plankton (drifters)– Nekton (swimmers)
• Benthic (along the bottom)
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
Consumers
• Primary consumers– Eat producers
• Secondary Consumers– Eat primary consumers
• These all are Trophic Levels
Primary Productivity
• Refers to how active the producers are
• grams of Carbon bound into organic material per square meter per year (gC/m2/y)
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
• 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• Holoplankton
– Spend their entire life in plankton
• Major types – – Radiolarians– Foraminifers– Copepods– Krill– Jellyfish (cnidarians) and comb jellies
(ctenophores)
Zooplankton
• Meroplankton– Only found in plankton for part of their life
cycle– Larvae of benthic adults & fish