Marine Biology What it takes to be alive

© 2002 Brooks/Cole, a division of Thomson Learning, Inc. Being Alive What are characteristics of all living things? Living things:  contain matter in a highly organized state  can capture, store and transmit energy  are capable of reproduction  can change through time and adapt to their environment (in other words, they can evolve)

Energy Flow All living things need energy. Living things cannot create new energy, but they can convert one form of energy to another (plants convert light energy to chemical energy; animals convert chemical energy to energy of movement, etc) The main source of energy for living things is the sun.

Primary Production The synthesis (production) of organic materials from inorganic substances by photosynthesis or chemosynthesis is called primary production.

Primary Production –Photosynthesis is the process by which producers convert light energy from the sun into food energy uses sunlight, nutrients, carbon dioxide and water and produces glucose & oxygen –Chemosynthesis is the production of organic molecules (food) from inorganic molecules in the environment Energy is released when substances such as sulfur, ammonia, and hydrogen are oxidized by certain organisms (bacteria)

Think-a-minute….. 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Do ALL organisms undergo photosynthesis? Which ones do? Do ALL organisms undergo cellular respiration? respiration photosynthesis

© 2002 Brooks/Cole, a division of Thomson Learning, Inc. The Cycling of Matter The cycling of matter through living systems.

Terms used to describe feeding relationships Autotrophs – organisms that make their own food, also called producers (ex. plants, some bacteria) Heterotrophs - organisms that must consume other organisms for energy, also called consumers (ex. herbivores, carnivores, omnivores) Carnivores – organisms that eat other animals Herbivores – organisms that eat plants Omnivores – organisms that eat both animals and plants Decomposers - Obtain food (energy) from feeding on dead organisms, releasing nutrients back into the ecosystem (Ex: most fungi, many bacteria) Feeding Relationships

What terms are used to describe feeding relationships? Trophic pyramid - a model that describes who eats whom (similar to a food chain) Producers are at the base. Primary consumers - these organisms eat producers Secondary Consumers - these organisms eat primary consumers Top consumers - the top of the tropic pyramid Feeding Relationships

The Trophic Pyramid 10% energy transfer from one level to the next

Fig Trophic Pyramid - Example

Check for Understanding Make a Trophic Pyramid

Trophic Pyramid, Food Chains, & Food Webs Trophic Pyramid & Food Chains are similar, because it is a straight line from one organism to the next. –Phytoplankton (producer) get eaten by zooplankton or herbivorous fish (1° consumer), which get eaten by carnivorous fish (2° consumer). –Smaller fish get eaten by other, bigger fish (3° and 4° consumers).

Food Webs (fig. 13.6) A never ending cycle which shows energy flow through an ecosystem. As organisms feed on each other, energy – in the form of food – flows through the ecosystem. Producers Plants, Phytoplankton Consumers Animals Decomposers Bacteria, Fungi Nutrients Na, S, Cl, N, P

Food Webs (fig. 13.6) Food webs are more realistic because they account for other organisms, and environmental influences.

Elements of Life Four elements make up 99% of the mass of all living things –Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N) Nine other elements make up almost all of the rest of the mass Table 13.2

© 2002 Brooks/Cole, a division of Thomson Learning, Inc. Physical Factors Affecting Marine Life Any aspect of the physical environment that affects living organisms is a physical factor. What are the most important physical factors for marine organisms?  light  dissolved gases  temperature  acid-base balance  salinity  hydrostatic pressure  dissolved nutrients

Light Photosynthetic organisms need light!

Light Sunlight approaching the surface at a low angle gets reflected Some colors penetrate deeper than others (blue goes deepest) Depth of penetration depends on clarity of water (turbidity) Figure 13.11

Temperature Varies with depth (thermocline) and latitude Most marine organisms are cold-blooded Metabolic rate (rate at which energy- releasing reactions happen within an organism) varies with temperature –Metabolic rate increases at higher temperature (within limits)

Salinity Variable at surface due to rainfall, evaporation, runoff, etc Less variable at depth Change in salinity can damage cell membranes Change in salinity affects density of water & therefore the buoyancy of organisms (buoyancy=how well they float) Salinity can cause water to enter or leave a cell (osmosis)

Dissolved Nutrients Nutrient – compound required for the production of organic matter All organisms need nutrients to survive Main nutrients needed for primary production are nitrogen and phosphorus Nutrients are brought to the surface by upwelling

Dissolved Gases 3 main gases dissolved in seawater: –Nitrogen (N 2 ), Oxygen (O 2 ), Carbon Dioxide (CO 2 ) Where does nitrogen come from? –Exchange with atmosphere Why is nitrogen important? –Component of proteins, chlorophyll, and nucleic acids –Most organisms can’t use N 2 (gas) directly; it must first be fixed (bound with oxygen or hydrogen) into usable forms by specialized organisms, usually bacteria

Dissolved Gases 3 main gases dissolved in seawater: –Nitrogen (N 2 ), Oxygen (O 2 ), Carbon Dioxide (CO 2 ) Where does oxygen come from? –Exchange with atmosphere & photosynthesis How does oxygen get used up? –Respiration & decomposition Why is oxygen important? –Required by plants & animals for cellular respiration

Dissolved Gases 3 main gases dissolved in seawater: –Nitrogen (N 2 ), Oxygen (O 2 ), Carbon Dioxide (CO 2 ) Where does carbon dioxide come from? –Exchange with atmosphere, respiration & decomposition How does carbon dioxide get used up? –Photosynthesis Why is carbon dioxide important? –Required by plants for photosynthesis

Dissolved Gases Surface water contains more O 2 than deep water - Why? Exchange w/ atmosphere & plants are photosynthesizing at the surface Deep water contains more CO 2 than surface water - Why? No plants to use it up, more decomposition, cold water holds more gas, water under pressure holds more gas

Acid/Base Balance Average pH is around 8 (slightly alkaline) Dissolved substances in seawater help prevent broad changes in pH –When dissolved in water, CO 2 can turn to carbonic acid Warm, productive surface water slightly more alkaline (pH 8.5) –Producers using CO 2 Cold, deep water slightly more acidic (pH 7.5) –Respiration of animals & bacteria means more CO 2 present

Carbonate buffering

Hydrostatic Pressure Hydrostatic pressure – The constant pressure of water around an organism –Pressure increases with depth Moderate changes in pressure have little effect on organisms Organisms from deep can’t be brought to surface; most organisms from the surface can’t go too deep

Check for Understanding List the 7 physical factors and name one way each affects marine life

Limiting Factors A physical or biological necessity whose presence in inappropriate amounts limits the normal action of the organism A limiting factor is a factor found in the environment that can be harmful if present in quantities that are too large or too small. Any factor required for life can become a limiting factor.