Transcript Marine Ecology: Individuals and Popuations

Marine Ecology:
Individuals and Popuations
Individuals
Water column zonation
Dealing with life in water
Light, Nutrients, Space
Populations
The Species definition
Larval strategies and Recruitment
Endangered species
Water Column: Vertical
Zonation
Light, resources important
Shallow water, continental shelves: many neighbors
Open ocean: All organisms mobile
Uncoupled from the benthos
Schools versus individuals
Deep ocean:
Mobile in water column
“Feed or Breed”
Deep benthos
Life in the Ocean: Biogeography
Benthos usually limited to region
Some fish, mammals: all over ocean
Factors that affect biogeography:
Resource requirements: T, light, productivity, space
Larval dispersal rates, time in water column
Ocean currents, continent arrangement/ barriers
Interaction with other species
Anthropogenic effects
Life in Water: Light
Light very necessary to photosynthetic organisms
Plants, algae, cyanobacteria, symbiotic relationships
Day: photosynthesis:
Light + CO2 + Nutrients --> Sugars (E) + 02 (Released)
Night: respiration
O2 used by plants
Animals: Light is necessary
Direct: sight
Indirect: trophic pyramid
Life in Water: Nutrients
Plants: absorb from water
NO2, NO3, NH4
Iron, phospherous, potassium
Nutrients can be limiting!
Animals:
consume other organisms
decrease efficiency with
increase in trophic level
Microbial loop: recycler
Breakdown of detritus
--> release nutrients
Life in Water: Space
Not as important for mobile organisms??
Sessile organism: whole life on bottom
Space to grow, consume, breed
Can be limiting
Stone Crab
Predator on oysters on Florida Gulf coast
Space: burrows, shelters in tidal zone
Can be fairly dense population if enough oysters
Variety of predation behaviors per individual
Eat on site versus carry away and eat in privacy
Eat “continuously” versus every few days
Nutrients direct from oysters; oysters from filter feeding
on particulate matter; particulate matter ultimately
from dissolved nutrients
Light is necessary: visual sense is good
Predator avoidance: birds, humans
Populations
Group of monospecific organisms that reproduce
Small area to large area
Open or closed
Several populations with genetic contact: metapopulation
Species: can be metapopulation
The Species Concept
Species:
Biology: able to reproduce
Paleontology: morphology
--> Are there problems with these definitions?
Species potential range  actual range
New species: mutation, allopatric speciation
The idea of natural selection, “Survival of the Fittest”
Life History
r-selected species
many offspring, no parental input
K-selected species
fewer offspring with more care or parental input
r- versus K- selection is relative.
Live birth rare; most organisms: larval stage
Recruitment
Life mode: Clustering, gregarious behavior, pods, solitary
Death: recycled back into nutrients
Larval Strategies and
Recruitment
Almost all marine organisms: larvae
Invertebrates, fish
Larvae:
Planktotroph: long time in water column, feeding
Lecithotroph: settle quickly, “yolk” with nutrients
Larval survival
Recruitment
New individuals into population
Metamorphosis/settlement, survival, geneflow
* Most don’t
survive!
Population dynamics
Interannual and intra-annual variation
Larval mortality, juvenile mortality, adult mortality
Factors that regulate population size:
Limiting resources
Interactions with other species
Carrying capacity
Conchs aggregating in food search
Example: Evechinus echinoid
in New Zealand fjord
Live in shallow water, fully marine
Migrate into fjord on full moon, neap tide, spring
Aggregate and spawn
Larvae in estuary; into ocean
Eventually metamorphose and settle: few days, not far
Closed population?
Salmon: open or closed population?
Exotic species
Introduced species:
natural or human-caused
Many introduced organisms
don’t make it
Those that do are often
catastrophic to ecosystems
Outcompete local species
Decreased predation pressure
Niche expansion
Mussel
Littorina littorina sp.
Endangered Species
Population numbers too low
in danger of extinction b/c not
enough gene flow
Conservation
Goal: to increase population,
gene flow
Take off fishing pressure
Take pressure off resources
Sanctuary
Tissue samples
In the marine realm, how can this be
problematic? How is conservation
different for a clam, a fish, and a
whale?