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 increase in trophic level

Microbial loop: recycler Breakdown of detritus --> release nutrients --> 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.

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? Endangered Species