Oceanography Lecture Notes Outline

Life in the Ocean - An Overview

 

I. Lecture Content

            Definition of Life – What Does it Mean to be "Alive"?

            Biogeochemical Cycles – Carbon, Nitrogen, and Others

Physical Controls Affecting Life – Matter, Energy, and the "Zone"

Biological Controls Affecting Life – Life's Affect on Life

            Evolution of Marine Life – Change through Time

Classification of Marine Life – Taxonomy and Phylogenies

            Classification of Marine Habitats – The Various Living Zones

 

II. Defining Life

      A. Precise Formal Definition is Elusive

 

                        1. A definition of life must have the following criteria:

 

·        Highly organized structure(s)

 

·        Low-entropy state

 

·        Capture, store, transmit, and transform energy

 

·        Capable of reproducing

 

·        Adapt to the environment

 

·        Change through time

 

2. The intimate exchange of matter and energy between

    living and nonliving systems makes it difficult in many

   cases to draw a line where one stops and the other starts

 

3. The essential difference between living and nonliving

    systems is the living system's:

 

·        Ways of utilizing energy to move, grow and maintain

 

·        Functioning cells

 

·        Ability to reproduce

o       Generate new entities with similar cells

 

B. Life and Matter

            1. All living systems on Earth contain matter

·        Consist of 23 of 107 known chemical elements

 

·        Only four of these make up nearly 99% of the mass of all

     living things:

o       Oxygen

o       Carbon

o       Hydrogen

o       Nitrogen

 

                        2. The 23 elements in living things combine to form several

 classes of biochemicals essential to all life.  They are:

·        carbohydrates (sugars, starches, and cellulose)

·        lipids (fatty acids, fats, waxes, and oils)

·        proteins and enzymes

·        nucleic acids

 

3. The across-the-board sameness and occurrence of all

 the above substances in all living things on Earth strongly

 suggest a common origin (ancestor) to all groups of life

           

C. Life and Energy

            1. All living systems capture, store, transfer, and transform

     energy

 

2. Living systems not able to create energy - only change it

 

3. Different living systems have unique variations in how

     they capture, store, transfer, and transform energy

·        Photosynthesis of plants

 

·        Chemosynthesis of certain bacteria

 

4.  Organisms utilize energy input to both move, grow and

       maintain their highly ordered structures

 

·        Temporarily delays Second Law of thermodynamics

 

·        Work against entropy = lowering degree of disorder

 

5. Life derives its energy principally from the sun

·        Directly - Photosynthesizers (autotrophs)

·        Indirectly - Consume autotrophs (heterotrophs)

·        There are a few exceptions

o       Deep sea vent bacteria

 

6. Typical path of energy in living systems

·        Sunlight ▬► chemical energy ▬► kinetic energy ▬► heat

 

III. Biogeochemical Cycles

      A. Biogeochemical cycles defined

1. The movement of the atoms and small molecules (that

  life depends upon) between living and nonliving systems

 

2. The atoms and small molecules that life depends upon

   (making up the living tissue of organisms) are either:

 

o       Always on the move in and out of living systems

 

o       Locked away in the Earth

Ø      Sediments

Ø      Deeply buried rock

 

B. There are Several Major Biogeochemical Cycles

Ø      Carbon

Ø      Nitrogen

Ø      Silicon

Ø      Phosphorus

Ø      Iron

Ø      Trace Metals

 

             C. The Carbon Cycle

                         1. The largest of all cycles in terms of mass (see fig. 13.3)

·        Reservoirs include life, land, ocean and atmosphere

 

·        Forms include carbonate sediment and rock, hydrocarbon

fuels, gaseous CO2 in the atmosphere and dissolved gas in the

                                    ocean, in bodies of organisms, dissolved organic carbon, and

                                dissolved inorganic carbon-based ions, like carbonic acid

 

                         2. Carbon is the basic building block of all life on Earth

·        Ability to form long chains to which other atoms can attach

 

               3. Carbon enters the atmosphere and ocean in several ways

·        Life respiration

·        Volcanic eruption

·        Uplift, weathering, and erosion of carbonate rock

·        Burning of fossil fuels

 

               4. Carbon initially enters the living world in one main way:

·        Carbon fixation by photosynthesis

·        Either from the atmosphere or ocean

 

               5. Carbon moves through the living world in several ways:

·        Moving within a living organism

o                Incorporated into cells of organism for growth

§         45% of total used for organism growth

o                Respiration (converted to end product - CO2)

§         45% of total used in respiratio

o                Excreted as dissolved organic carbon (DOC)

§         10% of total lost to waste as DOC

 

·        Moving between living organisms

o       Plant matter eaten by animals

o       Animals eat other animals

 

                         6. The dissolved organic carbon is taken in by bacteria

 

                         7. Dead falling organic matter in ocean mostly converted to

                                    CO2 by respirating bacteria who consume detritus

 

                         8. The less than 1% of organic detritus not converted to

                      CO2 by bacteria in the water column or ocean bottom is

                      incorporated into carbonate sediment and buried

 

                         9. Buried carbonate sediment and rock in ocean bottom

                             will at some point get recycled back into the life cycle by

·         Uplift, weathering and erosion

·    Volcanic gas release of melted subducted sediments

 

             D. The Nitrogen Cycle

                         1.  The second largest of all cycles in terms of mass

·        See figure 13.4

 

·        Reservoirs include life, land, ocean and atmosphere

 

·        Forms include nitrate rocks and sediment, organic matter,

 gaseous N2 in the atmosphere, dissolved N2 in the ocean, in

                                    bodies of organisms, dissolved organic nitrogen, and

                                dissolved inorganic nitrogen-based ions like NH4+, NO3-, and

                                NO2-

 

                         2. Nitrogen is a basic building block of all life on Earth

·        Critical element in production of proteins, nucleic aids, and

   chlorophyll

 

               3. Nitrogen enters the atmosphere and ocean as follows:

·        Volcanic eruption

·        Uplift, weathering, and erosion of nitrogen material

 

               4. Nitrogen initially enters the living world in one main way:

·        Fixation of nitrogen by special organisms

·        Either from the atmosphere, land, or ocean

 

               5. Nitrogen fixation is the process by which nitrogen is

                    bound to either oxygen or hydrogen into a usable form

                    by living organisms

 

                      6. Usable nitrogen moves through the living world:

·        Moving within a living organism

o                Incorporated into cells of organism for growth

 

o                Denitrifying bacteria use reduced forms of nitrogen

       ions for respiration

 

o                Excreted as dissolved organic carbon (DON)

 

·        Moving between living organisms

o       Plant matter eaten by animals

o       Animals eat other animals

 

                         7. The nitrogen cycle is shown in Figure 13.4 (page 324)

 

             E. The Phosphorus Cycle

                         1.  The phosphorous cycle is relatively simple

·        Cycles in three loops (see Fig, 13.5)

 

·        Reservoirs include life, land, and ocean

 

·        Forms include phosphate rocks and sediment, organic

     matter, dissolved PO4 in the ocean, and in bodies of

    organisms

 

                         2. Phosphorus is a basic building material of all life on

                                    Earth

·        Critical element in binding of nucleic aids

·        Used in the molecules that fuel cells

·        Goes into calcium phosphate for bones, teeth, nails,

and shells

 

               3. Phosphorus enters the ocean as follows:

·        Volcanic eruption via precipitation and rivers

·        Uplift, weathering, and erosion of phosphorous material

     via rivers

 

               4. Phosphorus has three different cycles

·        Fast cycle - direct life-death-life

o       Days to years

·        Slower cycle - life-death-ocean

o       Hundreds of years

·        Slowest cycle -life-death-Earth

o       Millions of years

 

             F. The Silica Cycle

1. Very similar to phosphorus cycle

 

2. Silica used in connective tissue and marine shells

 

             G. The Iron Cycle and Other Trace Elements

1. Similar to phosphorus and silica cycles

·        Simple loops

·        Reservoirs include land, ocean, and organisms

·        Forms include iron-rich rock and sediment, iron oxides,

      dissolved iron, and iron in organisms

 

                        2. Iron is nearly insoluble seawater

·        Typically very low concentrations

·        Very reactive in seawater

·        Easily partitions into marine sediment

 

                        3.  Iron concentrations are typically so low that it becomes

                                    a limiting factor to the growth of organisms

 

             H. Limiting Factors in the Marine Environment

                        1. A limiting factor is any physical or biological necessity

                            whose presence in inappropriate amounts limits the

                            normal function of an organism

·        Element or nutrient

·        Sunlight

·        Temperature

·        Proper pH

·        Salinity

            

IV. Physical Factors Affecting Marine Life

             A. The Ocean is Marine Life’s Support System

1.      Depend on the oceans chemical constituents

 

2.      Depend on stable physical conditions

 

3.      Very intimate interrelationship between marine life and

            its ocean environment

 

4.      The various chemical and physical aspects that marine

     life rely on to survive are termed physical factors

 

5. The most critical physical factors for marine life are:

Ø      Sunlight

Ø      Temperature

Ø      Salinity

Ø      Dissolved nutrients and gases

Ø      pH balance

Ø      Hydrostatic pressure

 

             B. Sunlight is Essential to Most Marine Life

                         1.  Absolutely essential to photosynthesizing organisms

 

                        2. Transparency of ocean water to sunlight allows

                              photosynthesis to occur down to over 100 meters deep

 

                        3. Differential absorption of various wavelengths of light

                             with depth

 

                        4. Depth of water penetration also limited by particulate

                              matter in the water column

 

                        5. Latitude and atmospheric cloud cover also affect amount

                                    of sunlight penetrating ocean surface

 

             C. Water Temperature

                        1. Ocean temperatures vary with latitude and depth

 

Ø      Vast bulk of ocean’s water is near freezing

 

Ø      Only tropical and temperate surface waters get

     warmer

 

Ø      See Figure 13.12 for seawater temp variations

 

                        2. Great majority of marine organisms are “cold-blooded”

Ø      Cold-blooded = ectothermic or poikilothermic

 

Ø      Warm-blooded = endothermic or homeothermic

 

                        3. Rates at which biochemical reactions take place depend

                            on seawater temperature

 

Ø      Metabolic rate roughly doubles with a 10°C (18°F)

    increase in sea temperature

 

Ø      Warmer water ectothermic organisms have higher

     metabolic rates than their colder water cousins

 

4.  All marine organisms have external temperature ranges

 

Ø      Endothermic organisms have fairly narrow ranges

 

Ø      Ectothermic organisms have wider ranges

            

             D. Salinity

                   1. Ocean salinity can vary tremendously from place to place

Ø      Coastal areas near rivers

 

Ø      Isolated, high evaporative seas

 

Ø      Less variable with depth

 

Ø      Slightly saltier with depth

 

                        2. Salinity levels affect cell membranes of organisms

Ø      Changing salinity can damage cells membranes

 

Ø      Affects internal cell salt-water balance

 

Ø      Also affects buoyancy of an organism

 

             F. Dissolved Nutrients and Gases

                   1. Dissolved nutrients and certain gases are required by

                                    organisms to stay alive – they include:

Ø      Nitrogen (NO3-)

Ø      Phosphorus (PO43-)

Ø      Calcium

Ø      Silica

Ø      Iron

Ø      Trace elements

Ø      Oxygen

Ø      Carbon dioxide

 

                        2. The above necessary dissolved nutrients and gases are 

                          generally in short or limited supply in much of the ocean

 

Ø      Exception is CO2, which is rather abundant

 

Ø      These materials are depleted during times of rapid

     growth and/or reproduction cycles

 

3. Rapid photosynthesis depletes CO2 , but increases O2

 

4. Rapid respiration depletes O2, which in turn can cause a

 die-off, whereby decomposition of bodies by bacteria will

further decrease O2 levels, causing a larger, broad die-off

 

G. Acid – Base (pH) Balance

            1. Seawater is slightly alkaline

 

Ø      pH averages around 8

 

            2. Variations between 8.5 and 7.0 occur in seawater

 

Ø      Much smaller than that of soils

 

Ø      Affects dissolved concentrations of nutrients and gases

 

H. Hydrostatic Pressure

                        1. Great hydrostatic pressure has little to physical effects

                                     on marine life in ordinary situations

 

Ø      Deep water fish rapidly hauled to the surface by

      fisherman may experience critical effects

 

2. Hydrostatic pressure can affect degree of dissolution of

     elements and gases

 

I. Importance of Intermixing Physical Factors

  1.  Physical factors are closely interrelated

 

Ø      A change in one factor will typically cause a

     change in one or more other factors

 

Ø      See chart in Figure 13.13 for an example

 

V. Biological Factors Affecting Marine Life

             A. Biological Factors Defined

                        1. Biological factors are aspects of the marine environment

                         that are generated by marine organisms, which in turn

                         affect living marine organisms

 

                        2. Biological factors include the following:

 

Ø      Feeding relationships

Ø      Organism (population) density (crowding)

Ø      Organism waste products

Ø      Defensive behaviors

 

 

VI. Marine Life Adaptations to Marine Conditions 

             A. Diffusion, Osmosis, and Active Transport

                        1. Importance of moving water, food and wastes in an out

                                     of cells

 

                        2. Importance of moving water, food and wastes in an out

                                     between organism and environment

 

             B. The Surface-to-Volume Problem

                        1. Finding the right surface area to volume for both cells

                                     and the size of organism for optimum functioning

 

            C. Density and Buoyancy

                        1. Control of vertical movement of organism in water

                                     column

 

            D. Viscosity – Drag versus turbulence

                        1. Optimization of organism body shape for movement

                                    through seawater

 

                        2. Small animals have a drag problem

 

                        3. Large animals have a turbulence problem

 

            E. Water Movement

                        1. Ocean Currents

Ø      Pelagic drifting organisms

Ø       Vertical movements

 

                        2. Tidal fluctuations

                                   

                        3. Wave and surf action

 

VII. Evolution of Life in the Ocean

             A. Observations of Present Day Life on Earth

                        1. There is a great diversity of life forms

Ø      Millions of different species are already known

 

Ø      Filling millions of different environmental niches

 

                        2. There are a great number of similarities amongst life

Ø      Obvious

o       External structures and functions (body parts)

 

Ø      Hidden

o       Internal design (cellular and genetic levels)

 

             B. Observations of Ancient Life in Earth's Rock Record

                        1. First signs of life found in rock almost 4 billion years old

 

                        2. Earliest life was very simple and primitive

Ø      Bacteria

Ø      Cyanobacteria

 

                        3. First animals with hard parts showed up around 500

                             millions years ago

Ø      Exclusively marine animals

 

Ø      Most of these organisms have been long extinct

o       Archeocyathids

o       Trilobites

o       Various shelled invertebrates

 

                     4. There has been a great diversity of life ancient forms

Ø      Hundreds of thousands of different species documented

 

Ø      Filling many different environmental niches

 

                        5. Number of similarities amongst ancient life

Ø      Obvious

o       External structures and functions (body parts)

 

                        6.  The assemblage of documented ancient organisms

               (now fossils) living at any given time in the past is

               totally unique to both, earlier or later assemblages of

                                    preserved ancient life

 

Ø      Shown at any given geographic level - local, regional, or

    global

 

Ø      Most recent fossils found in rock closely resemble the

     organisms alive today

 

Ø      Increasingly older fossils are progressively different

 

Ø      Systematic disappearance (extinction) of old forms

 

Ø      Systematic appearance (speciation) of new forms

 

Ø      Complexity of organisms has increased with time

o       Prokaryotes to eukaryotes

o       Single-celled to multi-celled organisms

o       Invertebrates to vertebrates

o       Fishes to Amphibians to Reptiles to Mammals

 

                        7. Great extinctions events happen every 50 to 100 MY

 

Ø      Each event wiped out a quarter to half of all species

 

Ø      Extinction events attributed to bolides & eruptions

 

                        8. Extinction events followed by explosion of new life forms

 

Ø      Uniquely new organisms would fill in new niches or old

     niches left open from recently extinct life forms

 

             C. What is Evolution?

                        1. Evolution defined:

Ø      Change through time

 

2. Facts about Nature:

Ø      The Universe has changed through time

Ø      Our solar system has changed through time

Ø      The physical Earth has changed through time

Ø      Life on Earth has changed through time

 

3. Interpretations that Best explain the observed changes:

Ø      The Big Bang theory

Ø      Theory of Stellar evolution

Ø      The Solar System accretion theory

Ø      The Plate tectonic theory

Ø      The theory of Biologic evolution

 

D. The Theory of Life Evolution

            1. Biologic Evolution defined:

Ø      The change in heredity characteristics of groups of

    organisms over the course of generations due to the

    combined affects of genetic mutation, natural selection,

    and geographical isolation

 

2. Charles Darwin is credited with proposing evolution by

natural selection

 

                        3. Natural selection defined:

Ø      Greater reproductive success among particular members

     of a species arising from genetically determined

     characteristics that confer an advantage in a particular

     environment

 

4. Genetic mutation defined:

Ø      Inheritable change in the make-up of an organisms genes

    (traits)

 

Ø      Both favorable and unfavorable mutations occur

 

Ø      Favorable mutations are the ones that provide an organism

     with an environmental advantage

 

5. Geographical isolation defined:

Ø      Physical barriers to gene flow

o       Mountain ranges

o       Oceans

o       Deserts

 

Ø      Physical barriers come and go with time

o       Plate tectonics the primary agent

 

6. New species emerge when natural selection and genetic

                    mutation are able to proceed within a geographically

   isolated population (gene pool) with sufficient time 

 

7. Opposition to the Theory of Evolution has come mainly from

                              Christian groups who favor creationism or intelligent design

Ø      Nonscientific views based mainly on Bible scripture

 

VIII. Classification of Marine Life

   A. Classification Systems Divide Life Based Upon Likeness

                        1. Study of biological classification is termed taxonomy

 

                        2. A classification system based upon only on gross

external physical and behavioral similarities is termed

an artificial system of classification

Ø      Example is grouping all life forms that swim into a single

     category or group

Ø      List would include humans, polar bears, seals, whales,

        all types of fish, squid, jellyfish, etc

 

            3. A classification system for living organisms based upon

       on the total number of structural and biochemical

      similarities is termed a natural system of classification

 

Ø      Arranged in an order that is

o       Logical

o       Systematic

o       Hierarchal

 

Ø      Example is grouping of all types of turtles into a

      single category or group, regardless of whether

      or not they can swim

 

            4. A classification system for ancient organisms based

       upon on the total number of structural similarities is

       also considered a natural system of classification

 

Ø      Arranged in an order that is

o       Logical

o       Systematic

o       Hierarchal

 

Ø      Example is grouping of all types of ancient

      trilobites into a single category or group, based

      on unique morphological characteristics

 

B. Modern Natural Classification System of Life Forms

            1. Modern phylogeny is based upon several criteria:

 

Ø      Physical, biochemical, and genetic structures

 

Ø      Evolutionary relationships

 

      2. Father of modern biological phylogeny - Carolus Linnaeus

 

               3. Contains Six Supreme Categories

Ø      Termed Kingdoms

 

Ø      Five are "natural"

o       Archaea

o       Bacteria

o       Fungi

o       Plantae

o       Animalia

 

Ø      One is "unnatural"

o       Protista

 

Ø      Study Figure 13.9 and Table 13.2

 

3. Further subcategories based on hierarchy

Ø      Degree of similarity, complexity, grade, or class

 

Ø      Largest category at the top

o       Kingdom

o       Very few groups at kingdom level

 

Ø      Smallest category at the bottom

o       Species

o       Very large number of groups at species level

 

4. Seven hierarchal subcategories beneath kingdom

Ø      Phylum

Ø      Subphylum

Ø      Class

Ø      Order

Ø      Family

Ø      Genus

Ø      Species

 

Ø      See Figure 13.10

 

5. Naming a specific animal includes two names

Ø      Genus

Ø      Species

Ø      An animal's scientific name

 

IX. Classification of Marine Habitats

             A. Based Upon Homogeneity of Environmental Features

                        1. Classification based on similar sunlight characteristics

 

                        2. Classification based on similarity in physical location

            B. Classification by Sunlight

                        1. Classification is based upon the intensity or absence of

                                    sunlight within the ocean water column

 

                        2. Photic zone

Ø      Uppermost layer of the ocean that is sunlit

 

Ø      Includes the upper 600 meters of ocean column

 

Ø      Varies in maximum depth according to location

 

Ø      Region where photosynthesis takes place

 

                        3. Euphotic zone

Ø      Upper part of photic zone

 

Ø      Plant production by photosynthesis exceeds the loss of

     carbohydrates by plant respiration

 

                        4. Disphotic zone

Ø      Lower part of photic zone

 

Ø      Loss of carbohydrates by plant respiration exceeds plant

     production by photosynthesis

 

                        5. Aphotic zone

Ø      Lies beneath the disphotic zone

 

Ø      Photosynthesis is unsustainable or impossible

 

Ø      This dark zone is the largest region of the ocean

 

            C. Classification by Location

                        1. Primary division is between ocean water column and

                             ocean bottom

Ø      Pelagic zone = Open water

 

Ø      Benthic zone = Sea bottom

 

                        2. Pelagic zone divided into two subzones:

Ø      Neritic zone = near shore over the continental

                               shelves

 

Ø      Oceanic zone = Offshore over deep water

 

Ø      Free-swimming and floating organisms dwell here

 

 

                        2. Benthic Zone is divided into several subzones

Ø      Littoral zone = intertidal bottom

 

Ø      Sublittoral zone = continental shelf bottom

                                                      seaward of littoral zone

 

Ø      Bathyal zone = Continental slope and rise bottom

 

Ø      Abyssal zone = Vast true ocean basin bottom

 

Ø      Hadal zone = super deep ocean bottom; trenches

 

Ø      Burrowing, attached, crawling, and swimming

       organisms found on or in the bottom

 

            D. Classification of Organisms by Behavior

                        1. Primary division is based upon both, the organism’s    

                                    ability, or lack of ability, to stay suspended in the

                                     water column

 

Ø      Pelagic = Floating, suspended in water column

 

Ø      Benthic = Living on or in the bottom

 

                        2. Pelagic organisms divided into two groups

 

Ø      Plankton = suspended; passive-swimmers

 

Ø      Nekton = active swimmers

 

X. Life In the Ocean Vocabulary - Chapter 13

 

abyssal zone

active transport

adaptation

Animalia

aphotic zone

Archaea

artificial system of classification

Bacteria

bathyal zone

benthic zone

biogeochemical cycle

biological factor

carbon factor

convergent  evolution

Darwin, Charles

denintrifying bacteria

diffusion

disphotic zone

dissolved organic carbon (DOC)

dissolved organic nitrogen (DON)

drag

ectotherm, ectothermic

endotherm, endothermic

energy

entropy

eukaryote

euphotic zone

evolution

hadal zone

hierarchy

hydrostatic pressure

hypertonic

hypotonic

isotonic

kingdoms

limiting factor

Linnaeus, Carolus

littoral zone

mass extinction

metabolic rate

mutation

natural selection

natural system of classification

nekton

neritic zone

nitrifying bacteria

nitrogen cycle

nutrient

oceanic zone

osmosis

pelagic

pelagic zone

photic zone

phylogeny

physical factor

plankton

Plantae

prokaryote

Protista

scientific name

second law of thermodynamics

species

sublitttoral zone

surface-to-volume ratio

taxonomy

theory of evolution

turbulence

viscosity

zone