1. Fundamentals of Ecology
Chapter 2
Fundamentals of Ecology

2. Study of Ecology Ecology Ecosystems
Ecology
Study of relationships among organisms.
Study interactions of organisms with their environment.
Ecosystems
Composed of living things and their nonliving environment.
All ecosystems combined make up biosphere (part of the world that supports life).

3. Study of Ecology Environment Habitat: where an organism lives
All factors acting on an organism.
Biotic (living) or abiotic (nonliving) factors
Internal or external.
Habitat: where an organism lives
Marine habitats characterized by abiotic features (physical & chemical characteristics).
Abiotic features determine what type of organism can live there.

4. Coral reef habitat: large habitat containing thousands of small microhabitats, such as crevices in the coral.
Microhabitat is small subdivision of larger habitat.

5. Study of Ecology
Niche: an organism’s environmental role or occupation in habitat.
Examples: mussels stick to rocks and filter seawater for food.
Full description of niche includes range of physical & biological factors affecting ability to survive and reproduce.
Physical: water levels, salinity, exposure to air, rocks, etc.
Biological: predator prey relationships, parasites, competition for resources, etc.
Organism’s behavior also defines niche.
How it feeds, mates, social behaviors, etc…

6. Environmental Factors Affect Organism Distribution
Maintaining homeostasis
Internal balancing of factors occurring as a result of changes in the external environment.
Changes in temperature, salinity, nutrient levels, etc.
Internal adjustments to maintain a stable internal environment

7. Environmental Factors Affect Organism Distribution
Maintaining homeostasis
Homeostasis affects the distribution of marine organisms.
Range of tolerance for different environmental conditions:
optimal range – organism survives & reproduces best in this range
zone of stress – above or below optimal range
zones of intolerance – organism cannot survive

8. In zone of intolerance organisms unable to exist.
Organism survives & reproduces best when conditions within optimal range.
Organism can live within stress zone but spends energy maintaining homeostasis and not as much for reproduction.
In zone of intolerance organisms unable to exist.
© 2006 Thomson-Brooks Cole

9. Environmental Factors Affect Organism Distribution
Physical environment
Includes sunlight, temperature, salinity, pressure, nutrients, & wastes.

10. Environmental Factors Affect Organism Distribution
Sunlight
Photosynthesis
Phytoplankton: largest group of photosynthetic organisms in marine environment.
Distribution determined by amount of sunlight & nutrients available.
Vision
Needed to capture prey, avoid predation, and communication.
Desiccation
Drying out due to excessive exposure to sunlight.

11. Environmental Factors Affect Organism Distribution
Temperature
Ectotherms:
Obtain most of body heat from surroundings.
A lot of simpler marine animals.
Endotherms:
Maintain constant body temperature because of metabolism - chemical reactions within cells.
Marine mammals and birds.

12. Environmental Factors Affect Organism Distribution
Temperature influences distribution of organisms in shallow water & in intertidal zone (tide pools).
Covered during high tide & exposed at low tide.
Water temperatures in these zones change rapidly & substantially.
Organisms must adapt to large fluctuations in temperature.

13. Environmental Factors Affect Organism Distribution
Salinity
Measure of concentration of dissolved inorganic salts in the water.
All organisms must maintain balance of water & solutes in their body to keep cells alive.
Water may move across cell membranes to achieve this balance.
Cells may gain or lose too much water through osmosis.

14. Isotonic Solution:
Cell in solution with same concentration of dissolved solutes as inside the cell.
No net movement of water.

15. Hypertonic solution:
Solution has a higher concentration of dissolved solutes than inside the cell.
Cell loses water (moves out of cell), becomes dehydrated, shrivels, & dies.

16. Hypotonic Solution:
Solution has lower solute concentration than inside cell.
Net movement of water into cell, cell swells, & possibly bursts.

17. Environmental Factors Affect Organism Distribution
Salinity and marine organisms
Often live in water with a high salinity.
Open ocean is more stable environment with minor fluctuations in salt concentrations.
Coastal areas can have large fluctuations in salt content (evaporation & rain/runoff).

18. Environmental Factors Affect Organism Distribution
Pressure
760 mm Hg or 1 atmosphere at sea level.
Increases 1 atmosphere for every 10 meters (33 feet) below sea level.
Surface dwelling organisms therefore unable to survive at great depths because of increased pressure.

19. Environmental Factors Affect Organism Distribution
Special adaptations allow for survival at great depths.
Sperm whale rib cage & lungs collapse when dive to great depths.
No excessive body cavities (such as swim bladder) that can collapse under pressure.
Bones & flesh often flabby.

20. Environmental Factors Affect Organism Distribution
Metabolic requirements
Availability of nutrients affects distribution of organisms.
Nutrients: all organic and inorganic material needed for growth, reproduction, and metabolism.
Ex: nitrogen and phosphorus.
Limiting nutrients: limit the number & distribution of marine organisms.

21. Environmental Factors Affect Organism Distribution
Oxygen as a requirement for metabolism:
Produced by photosynthesis & needed in cellular respiration to make ATP.
Ability for water to dissolve oxygen depends on temperature & salinity.
Cooler & less salty dissolves more oxygen (open ocean as compared to tide pools).

22. Environmental Factors Affect Organism Distribution
Anaerobic organisms
Anaerobic survive in absence of oxygen.
Found in ocean’s depths, salt marshes, sand, & mud flats.
Aerobic organisms
Require oxygen for metabolism.

23. Environmental Factors Affect Organism Distribution
Too much nutrient material can be a problem.
Eutrophication: process of nutrient enrichment due to water runoff from land into coastal waters.
Eutrophication leads to algal bloom – large number of photsynthetic plankton.
Decomposition of plankton leads to oxygen depletion of water creating anoxic area.

24. Environmental Factors Affect Organism Distribution
Metabolic wastes
Carbon dioxide is a common product of cellular respiration.
Excretion of nitrogen rich waste products by animals.
Release of oxygen from photosynthesis.
Often waste is broken down or recycled through ecosystem.
Problem when accumulation of excess of metabolic waste to toxic levels.

25. Environmental Factors Affect Organism Distribution
Biological environment
Includes all species with which the organism comes in contact & the ways the organism interacts with these species.
Includes competition, predator-prey relationships, & symbiosis.

26. Environmental Factors Affect Organism Distribution
symbiosis: living together
Effect on one species results in a change in the other
mutualism – both organisms benefit from the relationship
commensalism – one organism benefits, whereas the other is neither harmed nor benefited
parasitism – the parasite lives off the host; the parasite benefits while the host is harmed

27. Environmental Factors Affect Organism Distribution
Competition
When organisms require same limited resource (food, mates, etc).
May be interspecific (between similar species) or intraspecific (between members of the same species).
Prevents two different groups of organisms from occupying the same niche.

28. Environmental Factors Affect Organism Distribution
Competition
May result in competitive exclusion (local extinction of less successful competitor).
Resource partitioning allows organisms to share a resource.
For example: plankton feeding fishes
some feed during day (sea bass & damselfish) & some at night (soldierfish)

29. Environmental Factors Affect Organism Distribution
predator-prey relationships
balance of abundance of prey vs. predators
Herbivores: eat plants
Carnivores: eat other animals
As predator number increases, amount of prey decreases, and predator number then begins to decrease causing rise in prey population

30. Environmental Factors Affect Organism Distribution
keystone predators
Presence in community allows other species to live
Effect on biological diversity is disproportionate to its abundance (small number of predators have large effect)

31. Populations and Communities
Population – a group of the same species that occupies a specified area.
Interact and breed with each other.
Different populations separated from each other by barriers preventing successful breeding.
Community – composed of populations of different species that occupy one habitat at the same time.
Different species related through competition, predator-prey relationships, and symbiosis.

32. Populations and Communities
Population growth
There are many ways in which a population can increase in size.
Birth rate can exceed death rate.
Recruitment: addition of new members to population through reproduction or immigration.

33. Populations and Communities
Population growth
Exponential or Logarithmic Growth
J shaped curve for rapidly growing population.
Initial growth is slow followed by rapid doubling of the population.
This type of growth only sustained for short periods of time due to resource limitation.
Example: phytoplankton undergo rapid population increase called blooms when nutrients available.

34. Populations and Communities
Population growth
Logistic growth
Original growth pattern is exponential.
Then rate of population increase reaches equilibrium & eventually becomes zero.
Population reaches equilibrium when at the maximum number of individuals that the environment can sustain (carrying capacity).
Physical or biological factors can limit population growth.

35. Exponential growth
Logistic growth: reaches carrying capacity & graph flattens out.

36. Populations and Communities
Distribution of marine communities
Designated by regions of ocean they occupy.
Pelagic division (ocean’s water or water column).
Benthic division (ocean bottom)
Divisions further subdivided into smaller zones based on distance from land, light availability, and depth.

37. Ecosystems: Basic Units of the Biosphere
Ecosystem: interaction of biological communities & their physical environment.
Examples of ecosystems: estuaries, rocky shores, kelp forests, and coral reefs.

38. Ecosystems: Basic Units of the Biosphere
Energy flow through ecosystems
Organisms require energy for all aspects of life.
Ultimate source of energy for life on earth is sun.

39. Ecosystems: Basic Units of the Biosphere
Food chains and food webs: establish feeding relationships
Food chain shows feeding relationship in linear sequence from producer to consumer (arrow shows direction of energy flow).
Food web shows several food chains linked together & more complex feeding relationships.

40. Food Chain: Linear sequence of feeding relationships

41. Food Web: interconnecting feeding relationships

42. Ecosystems: Basic Units of the Biosphere
Producers
Photosynthetic producers: convert radiant energy from of the sun into chemical energy in food molecules.
Chemosynthetic producers: use energy from chemical reactions to form organic molecules.
Example: bacteria of the ocean floor near deep sea vents.

43. Ecosystems: Basic Units of the Biosphere
Autotrophs (producers): able to make their own food & food for others.
In marine environment, primary photosynthetic organisms are phytoplankton, seaweeds (multicellular marine alga visible to naked eye), and plants.

44. Ecosystems: Basic Units of the Biosphere
Primary productivity: rate at which energy-rich food molecules are being produced from inorganic matter.

45. Ecosystems: Basic Units of the Biosphere
Consumers (heterotrophs)
First-order consumers (herbivores): feed directly on producers
Second-order consumers: carnivores that feed on herbivores
Third-order consumers: carnivores that feed on other carnivores

46. Ecosystems: Basic Units of the Biosphere
Omnivores: eat everything.
Detrivores: feed on animal waste & decaying tissue.
Decomposers: break down tissue of dead organisms & recycle nutrients.

47. Ecosystems: Basic Units of the Biosphere
Trophic levels:
Energy storage level
Number of trophic levels is limited because only a fraction of the energy at one level passes to the next level.

48. Ecosystems: Basic Units of the Biosphere
Ecological efficiency
Percentage of energy passed from one trophic level to the next.
Ten percent rule: average of 10% passed from one trophic level to the next.
Trophic pyramids
As energy passed on decreases, so does the number of organisms that can be supported.

49. Energy pyramid: decrease of available energy from one trophic level to the next.
Pyramid of Numbers: size of each box represents number of organisms supported at each level.

50. Pyramid of Biomass: mass of living organisms that each level can support.

51. Biogeochemical Cycles
Hydrologic or Water Cycle
Water is lost through evaporation & transpiration from vegetation.
Returned through precipitation and runoff.

52. Hydrologic or Water Cycle

53. Biogeochemical Cycles
Carbon Cycle
Released from organisms in the form of carbon dioxide through respiration and decomposition.
Recycled by photosynthetic producers.
Used in shells, corals and skeletons as part of calcium carbonate.
Fossil fuels formed from deposits of dead & decaying organisms.

55. Biogeochemical Cycles
Nitrogen cycle
Producers use nitrogen to synthesize proteins.
Nitrogen passed to consumers via food chain.

56. Biogeochemical Cycles
Animals excrete nitrogen in the form of ammonia, urea, or uric acid.
Bacteria recycle nitrogen from wastes and decomposing, dead organisms.
Fixation of atmospheric nitrogen by microorganisms: convert atmospheric nitrogen into usable form.