Ecology

1. Ecology • Study of the relations of organisms to one another and to their surroundings • We seek to understand the order of the natural world • Can we identify patterns and connections between organisms and their physical /chemical environment? • Can we find underlying mechanisms that produce the patterns? • Can we predict these patterns?

2. Natural History • Ecologists understand nature by: • Asking questions • Discovering connections • Developing a detailed understanding of natural phenomena • Natural History forms the basis of ecology

3. Levels of Complexity Solar system Planet earth Ecosystems Communities Populations Organisms Cells Molecules Atoms Sub-atomic particles

4. Ecological Questions • “Ecology starts with a question” • Proximate Questions • Questions about mechanisms or functions underlying current patterns • Ultimate Questions • Questions about selective pressures over evolutionary time

5. Individual • Autecology – relationship between individual organisms and their environment • Ecophysiology • Evolutionary ecology - study of adaptation

6. Population ecology •A group of same species inhabiting a particular area • Study of – Species properties (birth rate, death rate) – Interactions with environment that determine population size (& structure)

7. Community • Species that occur together in space and time or • An association of interacting populations, usually defined by the nature of their interactions

8. Community Structure • Species composition • Relative abundance • Size • Trophic relationships • Species diversity What controls structure?

9. Processes • Competition • Predation/grazing • Supply side ecology – settlement / recruitment • Habitat modification

10. Ecosystems Ecology • An ecosystem is a biotic community and the abiotic environment, and is the functional system that transfers and circulates energy and matter. • Ecosystems ecology is concerned with interactions between organisms and their environments, and the fluxes of energy between different elements of food webs, and of materials such as nutrients (e.g., Nitrogen and Phosphorus)

11. Ecosystems Are Energy Transformers • J.M. Teal (1962)

12. Terrestrial vs Marine Environments • Physical and Chemical Differences • Seawater is much denser than air(= organisms float in it readily) • Result: Aquatic ecosystems evolved a whole community of floating organisms (plankton) . Nothing comparable on land, and a fundamental difference. • All other marine organisms are bathed in seawater which contain this planktonic community. • Has Led to the evolution of filter feeding organisms • Dispersal stage for many organisms which produce larvae which can and do become part of the plankton

13. Terrestrial vs Marine Environments • Physical and Chemical Differences • 2. Seawater strongly absorbs light (most of the light is gone below 100m). • Most of the world’s oceans are without light which prevents primary production in these areas (they then must rely on energy that drops down on them from the productive zone above).

14. Terrestrial vs Marine Environments • Physical and Chemical Differences • Gravity –because bouyancy is provided by the seawater, organisms do not have to invest as much energy in skeletal material (bone, cellulose) • Movements on land are energetically more costly – so terrestrial forms require greater concentrations of energy. • Land formsSea forms • -carbohydrates - proteins • -long lived - short lived • slow growing - rapid growth • rich in stored energy - do not store energy Exceptions?

15. Terrestrial vs Marine Environments Physical and Chemical Differences 4. O2 can be limiting in marine environments Has consequences for the distribution and abundance of many marine organisms because areas can be so low in Oxygen that they cannot support life.

16. Terrestrial vs Marine Environments Biological Differences LandSea a. Large plants dominate the system (long lived) b. Dominant herbivores – large (insects to elephants) c. Plant Community matrix -mostly indigestible -small portion of individual plant removed at any one time by herbivores (deer taking leaves off shrubs = partial predation) a. Microscopic plants dominate (with few exceptions most areshort lived) b. Dominant herbivores – small (mostly microscopic, like copepods) c. Plant is consumed in its entirety (predation)

17. Differences in Primary Producers

18. Terrestrial vs Marine Environments Biological Differences LandSea a. Large plants dominate the system (long lived) b. Dominant herbivores – large (insects to elephants) c. Plant Community matrix -mostly indigestible -small portion of individual plant removed at any one time by herbivore (deer taking leaves off shrubs = partial predation) a. Microscopic plants dominate (with few exceptions are short lived) b. Dominant herbivores – small (mostly microscopic, like copepods) c. Plant is consumed in its entirety

19. Differences in herbivore size

20. Terrestrial vs Marine Environments Biological Differences LandSea d. On land, fauna is short lived compared to plants (commonly named by dominant plant; maple forest, tall grass prairie) e. Large animals are often herbivores (lower trophic level) f. Generally, production higher, transfer of energy less efficient (from 1st to 2nd level) d. In sea, fauna is long lived compared to plants (commonly named for dominant animal; oyster reefs and coral reefs e. Large animals are often carnivores (higher trophic level) f. Production lower, transfer of energy more efficient (from 1st to 2nd level)

21. Differences in ages Terrestrial fauna short lived in comparison to plants (deciduous forests), marine fauna are long-lived when compared to plants (coral reefs)

22. Terrestrial vs Marine Environments Biological Differences LandSea d. On land, fauna is short lived compared to plants (commonly named by dominant plant; maple forest, tall grass prairie) e. Large animals are often herbivores (lower trophic level) f. Generally, production higher, transfer of energy less efficient (from 1st to 2nd level) d. In sea, fauna is long lived compared to plants (commonly named for dominant animal; oyster bank/ coral reef e. Large animals are often carnivores (higher trophic level) f. Production lower, transfer of energy more efficient (from 1st to 2nd level)

23. Differences in predator sizes • And, the largest marine predators and their prey are larger by 1-2 orders of magnitude than continental predators and their prey

24. Terrestrial vs Marine Environments Biological Differences LandSea d. On land, fauna is short lived compared to plants (commonly named by dominant plant; maple forest, tall grass prairie) e. Large animals are often herbivores (lower trophic level) f. Generally, production higher, transfer of energy less efficient from 1st to 2nd trophic level) d. In sea, fauna is long lived compared to plants (commonly named for dominant animal; oyster bank/ coral reef) e. Large animals are often carnivores (higher trophic level) f. Production lower, transfer of energy more efficient, (thus, more trophic levels)

25. Time scale of study • Ecological: • Question is how organisms functionnow • How do contemporary processes act to maintain observed community structure? • Evolutionary • Question is the historyof how a community came to its present state over evolutionary time • How do species evolve in response to selection due to community processes?

26. Temporal and Spatial Scale Matters

27. Important Abiotic and Biotic Influences on the Distribution of Marine Organisms

28. Niches The fundamental niche is a multidimensional Ø hyperspace, defined by a species’ tolerance to all environmental variables . (Problem: how to measure all environmental variables? Answer: restrict attention to the few that matter most) The realized niche is usually a smaller Ø hypervolume, whose smaller size is due to the negative effects of biotic interactions .

30. Salinity Salts can cause organisms to lose water through osmosis. If this happens major disruptions in ionic concentrations of body fluids occur, resulting in severe stress or death. Thus, organisms that can’t regulate their internal salt content are restricted to waters where salt concentrations allow them to survive.

31. Open ocean Shallow coastal seas Estuaries Semi-enclosed seas (Baltic Sea) Hypersaline Seas (Red Sea) 32-38 (mean 35) psu 27-30 psu 0-30 psu <25 psu >40 psu Salinity varies with environment

32. Temperature in the Ocean • Temperature is one of the most important abiotic physical properties in the ocean • Temperature controls the rate at which chemical reactions and biological processes occur • As such, temperature can control the distribution and abundance of marine organisms and the function of marine ecosystems

33. Temperature controls faunal distribution patterns • Sea surface temperature varies greatly with latitude • Tropical (25oC) • Subtropical (15oC) • Temperate (5oC northern limit-2oC southern limit) • Polar <2oC

34. Temperature varies with depth • Thermocline is a A layer of water in which the temperature decreases rapidly with depth.

35. Light in the Ocean • Light is essential for many aspects of life in the ocean • Light supplies the energy used by autotrophs to convert inorganic matter into organic matter • Light availability decreases with increasing depth • Animal depend on light to move around, detect prey, predators and the timing of reproduction

36. Light penetration varies with depth and location • The depth to which different colors of light penetrate ocean waters. Water absorbs warm colors like reds and oranges (long wavelength light) and scatters the cooler colors (short wavelength light).

37. Dissolved Gases in the Ocean • Dissolved oxygen is added to the ocean via mixing with the atmosphere and photosynthesis • Dissolved oxygen is lost from the ocean via respiration by organisms • Dissolved oxygen is controlled by temperature and nutrient inputs • Increased nutrient inputs in terrestrial runoff can create hypoxia areas at the base of many watersheds which cause dramatic changes in marine communities

38. Origins of hypoxia

39. Waves and Tides • Waves transfer significant amounts of energy from the wind to the ocean • The frequency and intensity of waves and the materials they carry (wave shock) can play an important role in determining the composition of marine communities by • abrasion • crushing • pressure drag

40. Sediment Type • As a rule, muddy sediments support more infaunal organisms than do sandy sediments • More filter feeders occur in sand and more deposit feeders occur in mud

41. Nutrients • Nitrogen and phosphorus are most important, but other important nutrients for plants and animals include silicon and iron.

42. Dispersal • Planktonic larvae • Rafting • Movement by Humans

43. Biological Interactions • Factors such as competition, predation, parasitism and mutualism

44. Habitat Selection • Some organisms do not occupy all of their potential range, even though they are capable of dispersing into unoccupied areas • Therefore, individuals can choose not to live in certain areas, and the distribution of a species may be limited by the behavior of individuals in selecting where they live

45. Important New Discoveries in Marine Ecology over the Last three Decades • Deep-sea hydrothermal vents and other habitats that rely on geochemical energy rather than photosynthesis • Biodiversity of every marine habitat that is much greater than previously understood, as primarily revealed by molecular studies

46. Important New Discoveries in Marine Ecology over the Last three Decades (2) • Phytoplankton smaller than 2 micrometers, and mostly unknown, account for up to half of the oceans’ primary production • Using field experiments, ecologists found that complex, indirect effects among species (known as trophic cascades) can affect food webs profoundly and structure entire communities over large areas

47. Important Progress in Marine Ecology over the Last three Decades (3) • Humans have affected marine ecosystems world-wide and fundamentally via fisheries, aquaculture, addition of nutrients and chemical pollutants, introduction of non-native species and destruction and alteration of critical habitats

48. Shifting Baselines • http://www.shiftingbaselines.org/slideshow/index.html

49. History of Soft-Sediment Communities Ediacaran Cambrian