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 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 Volume Ratios

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/m 2 /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 O 2 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

Copepods Small crustaceans (<1 mm) Very abundant

Figure 14.5: Copepod diversity

Fig. 13-9, p. 265 Krill – Important in Antarctic Ecosystem

Fig c, p. 266

Zooplankton Meroplankton –Only found in plankton for part of their life cycle –Larvae of benthic adults & fish

Meroplankton