Ecosystems

1. Ecosystems

2. Important Terms • Ecosystem = a group of organisms and how they interact with their living and nonliving environment • Niche = an organisms role • Biotic = living or having lived recently • Abiotic = nonliving, long dead • Producer = converts energy from the sun, also called an AUTOTROPH

3. Consumer = eats other living things, also known as a HETEROTROPH • Primary, Secondary, Tertiary, Quaternary • Body of water = lake, river, pond, etc • Food chain = each organism feeds on the one below it • Food web = overlapping food chains in a community

4. Types of heterotrophs • Herbivores = eat plants • Carnivores = eat animals • Omnivores = eat both plants and animals (omni = all) • Detritivores = eat dead matter (called “detritus”) • Decomposers = break down organic matter

5. Decomposer • Organic matter = was or is living, made mainly out of carbon • Inorganic matter = non living, not made out of carbon • Biodiversity = diversity of life

6. Biosphere = the part of the earth where life exists • Environment = all the external factors influencing the life of organisms, such as light or food supply • Photosynthesis = to convert energy from the sun (more details to come later) • Population = the number of individuals in a species in one ecosystem

7. For the following slides, write in your notes whether the picture is a food web or food chain • List the producers and consumers in the pictures and what they eat.

13. Biogeochemical Cycles • What is a Biogeochemical Cycle? • Only so much matter on earth because it is acts as a closed system. • Energy enters as sunlight, but no matter usually exits or enters. • Open system: Energy AND matter are exchanged. • These cycles act as a way to recycle matter within the biosphere from one form to another.

14. Energy Vs. Matter • Energy is TRANSFERRED • One-way flow of energy through food-chains and food webs. • Energy from sun goes to plants, which then goes to consumers. • Each trophic level loses ~90% of energy as heat. • Only 10% of energy is used for life processes. • Matter is TRANSFORMED • This is why we have biogeochemical cycles. • Only have a given amount of matter because Earth is a closed ecosystem.

15. Nutrient Cycles • Carbon - key ingredient in living tissue • “Carbon-based” life forms • Nitrogen - required for amino acids used in protein synthesis • What are our sources of protein? • What do we use proteins for? • Phosphorus - required for DNA and RNA • Why is this important?

16. Water Cycle • Water is required by all living things on Earth, including us. • Cycles through atmosphere, ocean, and land

18. Water Cycle • Major processes that bring water into the atmosphere • Evapotranspiration • Evaporation - water heats up, forming water vapor, which then moves into atmosphere. • Transpiration - water from plant leaves evaporates. • Condensation • Cloud formation as water vapor in atmosphere cools, condensing into the small droplets that form clouds.

19. Water Cycle • Major process that brings water out of the atmosphere: • Precipitation • Droplets that formed clouds become to large and are released as snow, sleet, hail, or rain.

20. Water Cycle • Processes on land: • Runoff • Precipitation “runs” along land until it reaches a body of water, such as a lake, river, or ocean. • Seepage (aka infiltration) • Precipitation “seeps” (moves into) soil to form ground water below the soil’s surface. • Root uptake • Plants absorb ground water from soil via their roots.

21. Water Facts • 390,000 cubic kilometers of water evaporates and enters atmosphere each year. • Equivalent to 185,000,000,000,000,000 bottles of 2 litre soda pop. • Most evaporates from and precipitates back into the oceans… Why is this? • Ocean makes up nearly 75% of Earth’s surface. • Water that precipitates on land runs back through streams and rivers.

23. Carbon Cycle • How is carbon taken up and released? • Photosynthesis, respiration, decomposition • Erosion, volcanic activity, and other geological activity • Fossil fuel formation (deposition) • Human activity • All these activities transfer carbon dioxide.

24. Carbon Facts • 71% of world’s carbon is in the oceans. • Mostly as carbonate and bicarbonate (dissolved ionic forms of carbon dioxide). • 22% exists as fossils. • 3% contained in dead organic matter and phytoplankton. • 3% held in terrestrial ecosystems. • Only 1% within the atmosphere as carbon dioxide.

25. Carbon Cycle • How can carbon get into the ocean? • Respiration by ocean animals • Precipitation that contains dissolved carbon dioxide • Erosion of carbonate rocks formed from animal skeletons and shells

28. Phosphorus Cycle • Where is a majority of phosphorus located? • On land in rock and soil minerals. • In the ocean as sediment. • Small amount in living organisms, bound within organic molecules such as DNA and RNA as well as in skeletons of animals. • Unlike other nutrients, it DOES NOT enter the atmosphere.

29. Phosphorus Cycle • What is the major form that phosphorus is found in? • Phosphate compounds (PO43-)

31. Nitrogen Cycle • What form does most nitrogen exist in? • Nitrogen gas in the atmosphere (N2) • Why is this a bad thing? • This form is not readily usable by most organisms and is often considered inert. • “Inert” because of a triple covalent bond, which is a very strong chemical bond.

32. Nitrogen Cycle • How do we get to a usable form? • Bacterial nitrogen fixation • Atmospheric nitrogen fixation • Decomposition and excretion • Haber-Bosch process = synthetic fertilizer • What are these usable forms? • Ammonia (NH3), Nitrate (NO3-) and nitrite (NO2-).

33. Nitrogen Cycle • What can “fix” nitrogen to a usable form? • Bacteria • On root nodules of legumes such as beans; convert nitrogen gas to ammonia. • In soils, convert ammonia to nitrates and nitrites • Enzyme necessary for this requires that no oxygen be present.

34. Nitrogen Cycle • What process removes usable nitrogen? • Denitrification • Bacteria convert nitrates back into nitrogen gas

38. How Nutrients Effect an Ecosystem • Nutrient limitation • Similar to when a person has a deficiency in a vitamin or necessary nutritional component (like iron or calcium), ecosystems can have a deficiency in a given nutrient. • This nutrient is called the limiting nutrient, because it limits the primary productivity of an ecosystem.

39. How Nutrients Effect an Ecosystem • What is primary productivity? • The rate at which organic material is created by producers, such as plants on land or phytoplankton in the ocean. • What happens when a limiting nutrient no longer becomes limiting? • In the ocean, this creates an algal bloom.

40. How Nutrients Effect an Ecosystem

41. Limiting Nutrients • A limiting nutrient limits the amount of primary productivity an ecosystem is capable of… • In the ocean, nitrogen is limiting. • In freshwater, phosphorus is limiting. • An increase in a limiting nutrient can lead to algal blooms…

42. Algal Blooms • Increase in algae as a result of increased nutrient. • Step 1: Algae grow and reproduce rapidly. • Step 2: Algae die. • Step 3: Decomposers (bacteria) in the water take up all the oxygen via respiration as they break down the dead algae. • Step 4: Limited to no oxygen left for other animals in the water column. • Step 5: Other animals such as fish, die due to lack of oxygen.

43. Harmful Algal Blooms • Chemicals released from bloom can be dangerous • Paralytic shellfish poisoning (picture on right - Alexandrium tamarense) • Ciguatera (picture on left - Gambierdiscus toxicus) • Neurotoxic shellfish poisoning (Gymnodinium breve)