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

Diversity of Life

•Likely between 6-12 million species total•Likely about 1 million marine species•2000 new marine species discovered each year

• Land is more variable- leads to more species• Oceans more stable• Ex: temperature

Classifying marine organisms• Pelagic (in water)

– Plankton (drifters)– Nekton (swimmers)

• Benthic (along the bottom)

Life Cycle of a Squid

Divisions of the Marine Environment

Living in the Ocean:Advantage= Water everywhere•makes up large % of living organisms•supportive

Living in the Ocean:Disadvantage= Hard to move•Streamlining in larger organisms

Living in the Ocean:Advantage= Hard to move•Appendages to slow sinking in plankton

Common Problem:Surface Area to VolumeRatios

Primary Producers

• aka autotrophs

• Organisms that can capture solar energy and convert it to chemical energy by building organic compounds

• Photosynthesis

Fig. 12-2, p. 238

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

Figure 13.1

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)

Figure 13.18

Only 10% of “food” gets transferred to the next trophic level

Figure 13.19

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

Figure 13.6

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?

Figure 13.11a: Arctic Ecosystem

Figure 13.13a: Temperate Ecosystem

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

Figure 14.4: Foraminifers

Single-celled; shell made from calcium carbonate

CopepodsSmall crustaceans (<1 mm)Very abundant

Figure 14.5: Copepod diversity

Fig. 13-9, p. 265

Krill – Important in Antarctic Ecosystem

Fig. 13-10c, p. 266

Zooplankton

• Meroplankton– Only found in plankton for part of their life

cycle– Larvae of benthic adults & fish

Meroplankton