Marine Ecology
010
Ecology = the study of the interaction of organisms with their environments.
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, O2, pollution
The word "ecology" coined from Greek word "oikos", which means "house" or "place to live”.
• population growth
• competition between species
• symbiotic relationships
• trophic (=feeding) relationships
• origin of biological diversity
• interaction with the physical environment
Energy Flow & Nutrient CycleEnergy Flow & Nutrient Cycle
Food ChainsFood 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
• 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
Food ChainsFood Chains
NutrientsNutrients• 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
EnergyEnergy• 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
Energy Flow
Primary Producer
Primary Consumer
Secondary Consumer
Tertiary Consumer
Food Chain
Decomposer
zooplankton larval fish
fish
fungi
Energy Flow through an EcosystemEnergy Flow through an Ecosystem
heat heatheat
phytoplankton
sun
water
Nutrients
Transfer EfficienciesTransfer Efficiencies• Efficiency of energy transfer called
transfer efficiency
• Units are energy or biomass
Et = Pt
Pt-1
Pt = annual production at level t
Pt-1 = annual production at t-1
Transfer Efficiency ExampleTransfer Efficiency Example• Net primary production = 150 g C/m2/yr• Herbivorous copepod production = 25 g C/m2/yr
• Typical transfer efficiency ranges*Level 1-2 ~20%*Levels 2-3, …: ~10%
Et = Pt
Pt-1
= Pcopepods
Pphytoplankton
= 25 = 0.17150
Primary producers
Tertiary consumers
Secondary consumers
Primary consumers
1,000 J
10% efficiency
Deposit feeders, filter feeders, grazers
1,000,000 J sunlight
10,000 J
algae, seagrass, cyanobacteria, phytoplankton
100 J
1st order carnivores
10 J
2nd order carnivores
Feces
Growth
CellularRespiration
Food WebsFood Webs
• 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
Antarctic Food Web
Some Feeding TypesSome 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 LoopRecycling: 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
Solar Energy
Microbial Loop
CO2
nutrients
Phytoplankton
Herbivores
Planktivores
Piscivores
DOC
Bacteria Nanoplankton(protozoans)
Keystone Species
A species whose presence in the community exerts a significant influence on the structure of that community.
Keystone predator hypothesis - predation by certain keystone predators is important in maintaining community diversity.
Paine’s study on Pisaster and blue mussels
Keystone SpeciesKeystone Species
Algal turf farming by the Pacific Gregory (Stegastes fasciolatus)
An Ecological Mystery
An Ecological MysteryAn 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 OttersVanishing Sea Otters
• 1997: surveys repeated• Sea otter populations had declines by 90%
- 1970: ~53,000 sea otters in survey area- 1997: ~6,000 sea otters
• Why?- Reproductive failure?- Starvation, pollution disease?
Cause of the DeclineCause 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.
Ecological Succession
Climax StageClimax Stage
New Bare SubstrateNew Bare Substrate
Colonizing StageColonizing Stage
Successionist StageSuccessionist Stage
PRIMARY SECONDARY
Growth occurs on newly exposed surfaces where no soil exists
Ex. Surfaces of volcanic eruptions
Growth occurring after a disturbance changes a community without removing the soil
2 types of succession
• 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
Mount St. Helens
prior 1980
Mount St. Helens
May 18, 1980
Sep. 24, 1980
Mount St. Helens
Fireweed 1980 after eruption
2004
2012
Hanauma Bay Tuff Ring(shield volcano)
Succession after Volcanic Eruption
What organisms would appear first?
How do organisms arrive, i.e., methods for dispersal?
Volcanic eruption creates sterile environment
Mechanisms of Succession
Facilitation
Inhibition
Tolerance
Early species improve habitat.
Ex. Early marine colonists provide a substrate conducive for settling of later arriving species.
As resources become scarce due to depletion and competition, species capable of tolerating the lowest resource levels will survive.
Competition for space, nutrients and light; allopathic chemicals.
First arrivals take precedence.
r & K Selected Species
Pioneer species- 1st species to colonize a newly disturbed area
r selected
Late successional species
K selected
low competitive abilityshort life spanhigh growth rate
higher maternal investment per offspringlow reproductive output
high reproductive output
slow growth ratelong life spanhigh competitive ability
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)
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
Reef
Case 3
Case 2
Case 1Deep reef slope
Reef slope beneath reef crest
Near reef crest
Ecological Succession on a Coral ReefThe Big Island
Ecological Succession on a Coral Reef
Ecological Succession on a Coral Reef
Ecological Succession on a Coral Reef
Ecological Succession on a Coral Reef
Ecological Succession on a Coral Reef
Ecological Succession on a Coral Reef
Ecological Succession on a Coral Reef
Successional Models and their Impacts
Successional Models and their Impacts