Energy Flow & Nutrient Cycle 8/25/2015

Transcription

1 It involves understanding biotic and abiotic factors influencing the distribution and abundance of living things. Biotic Factors Competitors Disease Predators Food availability Habitat availability Symbiotic relationships Abiotic Factors ph Temperature Weather conditions Water availability Chemical composition of environment nitrates, phosphates, ammonia, O 2, pollution Energy Flow & Nutrient Cycle population growth competition between species symbiotic relationships trophic (=feeding) relationships origin of biological diversity interaction with the physical environment 1

2 Food Chains Artificial devices to illustrate energy flow from one trophic level to another Trophic Levels: groups of organisms that obtain their energy in a similar manner Food Chains Total number of levels in a food chain depends upon locality and number of species Highest trophic levels occupied by adult animals with no predators of their own Secondary Production: total amount of biomass produced in all higher trophic levels Nutrients Inorganic nutrients incorporated into cells during photosynthesis - e.g. N, P, C, S Cyclic flow in food chains Decomposers release inorganic forms that become available to autotrophs again Energy Non-cyclic, unidirectional flow Losses at each transfer from one trophic level to another - Losses as heat from respiration - Inefficiencies in processing Total energy declines from one transfer to another - Limits number of trophic levels 2

3 Energy Flow sun Energy Flow through an Ecosystem Food Chain Primary Producer Primary Consumer Secondary Consumer Tertiary Consumer phytoplankton zooplankton heat heat larval fish heat fish water Nutrients fungi Decomposer Transfer Efficiencies Efficiency of energy transfer called transfer efficiency Units are energy or biomass E t = P t P t-1 P t = annual production at level t P t-1 = annual production at t-1 Transfer Efficiency Example Net primary production = 150 g C/m 2 /yr Herbivorous copepod production = 25 g C/m 2 /yr E t = P t = P copepods = 25 = 0.17 P t-1 P phytoplankton 150 Typical transfer efficiency ranges *Level 1-2 ~20% *Levels 2-3, : ~10% 3

4 10% efficiency Tertiary consumers 10 J 2 nd order carnivores Secondary consumers 100 J 1 st order carnivores Primary consumers Primary producers 1,000 J Deposit feeders, filter feeders, grazers 10,000 J algae, seagrass, cyanobacteria, phytoplankton 1,000,000 J sunlight Feces Growth Cellular Respiration Food Webs Antarctic Food Web Food chains don t exist in real ecosystems Almost all organisms are eaten by more than one predator Food webs reflect these multiple and shifting interactions 4

5 Some Feeding Types Many species don t fit into convenient categories Algal Grazers and Browsers Suspension Feeding Filter Feeding Deposit Feeding Benthic Animal Predators Plankton Pickers Corallivores Piscivores Omnivores Detritivores Scavengers Parasites Cannibals Ontogenetic dietary shifts Recycling: The Microbial Loop All organisms leak and excrete dissolved organic carbon (DOC) Bacteria can utilize DOC Bacteria abundant in the euphotic zone (~5 million/ml) Numbers controlled by grazing due to nanoplankton Increases food web efficiency Microbial Loop Solar Energy CO 2 nutrients Phytoplankton DOC Herbivores Planktivores Piscivores Keystone Species A species whose presence in the community exerts a significant influence on the structure of that community. Bacteria Nanoplankton (protozoans) 5

6 Keystone predator hypothesis - predation by certain keystone predators is important in maintaining community diversity. Paine s study on Pisaster and blue mussels Keystone Species Kelp Forests 6

7 An Ecological Mystery Keystone Species Algal turf farming by the Pacific Gregory (Stegastes fasciolatus) An Ecological Mystery Long-term study of sea otter populations along the Aleutians and Western Alaska 1970s: sea otter populations healthy and expanding 1990s: some populations of sea otters were declining Possibly due to migration rather than mortality 1993: 800km area in Aleutians surveyed - Sea otter population reduced by 50% Vanishing Sea Otters 1997: surveys repeated Sea otter populations had declines by 90% : ~53,000 sea otters in survey area : ~6,000 sea otters Why? - Reproductive failure? - Starvation, pollution disease? 7

8 Cause of the Decline 1991: one researcher observed an orca eating a sea otter Sea lions and seals are normal prey for orcas Clam Lagoon inaccessible to orcas- no decline Decline in usual prey led to a switch to sea otters As few as 4 orcas feeding on otters could account on the impact - Single orca could consume 1,825 otters/year Ecological Succession The progressive change in the species composition of an ecosystem. 8

9 Ecological Succession New Bare Substrate Colonizing Stage 2 types of succession PRIMARY Growth occurs on newly exposed surfaces where no soil exists Ex. Surfaces of volcanic eruptions SECONDARY Growth occurring after a disturbance changes a community without removing the soil Successionist Stage Climax Stage For example, new land created by a volcanic eruption is colonized by various living organisms Disturbances responsible can include cleared and plowed land, burned woodlands 9

10 Mount St. Helens Mount St. Helens prior 1980 May 18, 1980 Sep. 24, 1980 Mount St. Helens Succession after Volcanic Eruption What organisms would appear first? How do organisms arrive, i.e., methods for dispersal? Fireweed 1980 after eruption Volcanic eruption creates sterile environment Hanauma Bay Tuff Ring (shield volcano) 10

11 Mechanisms of Succession Facilitation Early species improve habitat. Ex. Early marine colonists provide a substrate conducive for settling of later arriving species. Inhibition First arrivals take precedence. Competition for space, nutrients and light; allopathic chemicals. Tolerance As resources become scarce due to depletion and competition, species capable of tolerating the lowest resource levels will survive. r & K Selected Species Pioneer species- 1st species to colonize a newly disturbed area r selected high reproductive output high growth rate short life span low competitive ability Late successional species K selected low reproductive output higher maternal investment per offspring high competitive ability long life span slow growth rate r & K refer to parameters in logistic growth equation Ecological Succession on a Coral Reef Successional Models and their Impacts Case 1: No Disturbance (Competitive Exclusion Model) Case 2: Occasional Strong Disturbance (Intermediate Disturbance Model) Case 3: Constant Strong Disturbance (Colonial Model) 11

12 Case 1: No Disturbance (Competitive Exclusion Model) As the reef becomes complex, organisms compete for space. Dominant organism outcompetes other species. Occurs in stable environments. Results in low species diversity. Highly protected patch reefs within lagoons or protected bays Deeper water Case 2: Occasional Strong Disturbance (Intermediate Disturbance Model) Storms and hurricanes allow for other species to move in Dominant species would not be allowed to reach competitive exclusion After each disturbance have a recovery period Area of high diversity Case 3: Constant Strong Disturbance (Colonial Model) Constant exposure to disturbance Shallow environment High turnover of species r-selected species Case 2 Case 3 Near reef crest Reef slope beneath reef crest Case 1 Deep reef slope 12

13 The Big Island 13

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15 Successional Models and their Impacts TUGAS 3 Aliran Energi dan daur ulang nutrient di ekosistem pantai berbatu Semua organisme yang hidup dalam komunitas pantai berbatu membutuhkan energi untuk bertahan hidup. Bagaimana energi ini diperoleh dan berapa banyak yang diteruskan? Bagaimana organisme ini mendapatkan atom dan molekul untuk pertumbuhan dan perbaikan? dan bagaimana nutrisi ini diteruskan? Jawab Pertanyaan tersebut dalam bentuk MAKALAH 15