Ecology

1. Ecology • Oikos= house • 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 describe patterns and connections between organisms and their physical /chemical environment? • Can we predict these patterns? • Can we find underlying mechanisms that produce the patterns?

2. 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

3. Diversity • Natural world contains a diversity of living things

4. Interconnections • Species are dependant on one another for their survival

5. Natural World is Dynamic • Constant tension between change and equilibrium • Removal of organisms by death • Replacement by birth • Disturbance • Renewal and Replenishment

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

7. Ecological Inquiry is a Process • Question - generated through observation and exploration • Hypothesis - develop ideas about the answers to those questions • Test - evaluate competing possible answers through systematic observation and experimentation • Inference - use the results of observation and experimentation to make inferences about the natural world

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

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

10. 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)

11. Community • Species that occur together in space and time (Begon et al. 1990) • An association of interacting populations, usually defined by the nature of their interactions (Ricklefs 1990)

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

13. Patterns and Processes • Distribution, Abundance and Diversity • Competition • Predation/grazing • Supply side ecology – settlement / recruitment • Habitat modification

14. 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)

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

16. Terrestrial vs Marine Environments • Physical and Chemical Differences • Seawater is much denser than air(= organisms float in it readily) • Result: Aquatic ecosystems evolved 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. • Led to the evolution of filter feeding organisms • Dispersal stage for many organisms which produce larvae which can and so become part of the plankton

17. 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 (must rely on energy that drops down on them from the productive zone above).

18. 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?

19. 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.

20. 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 a shrub = partial predation) a. Microscopic plants dominate (few exceptions) (short lived) b. Dominant herbivores – small (mostly microscopic; copepods) c. Plant is consumed in its entirety

21. Differences in Primary Producers

22. 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 a shrub = partial predation) a. Microscopic plants dominate (few exceptions) (short lived) b. Dominant herbivores – small (mostly microscopic; copepods) c. Plant is consumed in its entirety

23. Differences in herbivore size

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 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)

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

26. 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)

27. 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

28. 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 2ndtrophic 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 trophic level)

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

30. Temporal and Spatial Scale Matters

31. Ecological vs. Evolutionary questions • Ecological studies much more readily done • Evolutionary studies rely less on direct experiment and more on comparative, observational, & theoretical methods • Evolutionary questions imply ecological questions • Ecological questions do not necessarily imply evolutionary questions

32. How can the fossil record be used to understand marine ecosystems? • Fossils provide the only direct evidence that life has evolved, or experienced radiation, over long spans of geological time. • Fossils also offer the only concrete evidence that millions of species have disappeared from the Earth, or suffered extinction at key points in the Geological Time Scale. Ottowia Olenoides Wiwaxia Amiskwia Anomolacaris Haplopherentis Naraoia Pikaia Hallucigenia Aysheaia Marrella Opabinia

33. Causes of species extinction • Typical life history traits: • Sessile life style enhances extinction (bivalve species) • Large body size increases extinction risk • Slow reproductive rate increases extinction risk • Lack of genetic variability increases extinction risk?

34. Some problems in using the fossil record to answer evolutionary questions • Perhaps the greatest challenge is in describing the enormous diversity of fossils, many of which are altered after they have been buried. • Only a small proportion of animals with hard parts leave recognizable fossils, thereby biasing the record of biodiversity.

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

36. 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 nich e is usually a smaller Ø hypervolume, whose smaller size is due to the negative effects of biotic interactions .

38. 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.

39. Salinity is not uniform within the world’s oceans

40. Salinity Varies with Latitude • Salinity is influenced by freshwater runoff from land, precipitation, and evaporation.

41. 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

42. Salinity increases with depth • Halocline is a layer of water in which the salinity increases rapidly with depth.

43. 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

44. 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

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

46. 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

47. 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).

48. 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

49. Origins of hypoxia

50. 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