Week 11: Classifying organisms, productivity and rocky intertidal communities Flashcards
Plankton
DRIFTERS
- surface
-most of earth’s biomass
Nekton
SWIMMERS
-can move around all throughout water
Benthos
BOTTOM DWELLERS
-touching bottom
Phytoplankton
Autotrophic- produce own food via photosynthesis (primary producers)
Zooplankton
Heterotrophic- cant produce own food
Plankton- classification
Life cycle
1. Holoplankton: organisms that spend entire life as plankton
2. Meroplankton: organisms that spend their juvenile or larval stages as plankton, then mature (ex squid)
Size
1. Picoplankton
2. Macroplankton
Benthos- Classification
- Epifaunal- on sediment
- Infaunal- in sediment
- Nekobenthos- swimming just above ocean bottom
Benthos- Life strategies
- Burrowers (infaunal): wiggle into sediment
- Epifaunal: attatch to sediment via byssal threads
- Borers: bore into hard rock
Divisions of the marine environment- based on sunlight
Photic zone
Aphotic zone (no sunlight)*below 600m
Photic zone
- Euphotic zone: bulk of biological productivity in the ocean; sunlight for photosynthesis (70m)
- Disphotic: not enough sunlight for photosynthesis (600 m)
Divisions of the marine environment - pelagic zones
- Epipelagic (200m)
- Mesopelagic (1000m)
- Bathypelagic (4000m)
- Abyssopelagic (6000m)
- Hadopelagic
Epipelagic
Light present
High O2
Mesopelagic
Twilight zone - little light
Low O2 levels
Bathylpelagic and abyssopelagic
Dark, create own light via bioluminescence
High pressure
Live on detritus (remains of organisms)
Divisions of the marine environment- Benthic environment
Intertidal
Sublittoral
Bathyal
Primary productivity
Rate at which organisms store energy through the formation of organic matter (carbon-based compounds) from inorganic carbon
*Biomass formation
Measuring primary productivity
gC/m2/yr
What effects primary productivity?
- Solar radiation
- Nutrient availability
- Water temp
Solar radiation and productivity
Light reaches 1000m deep but not enough for photosynthesis, has to be euphotic zone
- more nutrients, light doesn’t travel as deep
- less nutrients, light travels deep
Limiting factor
A biotic or abiotic factor that restricts number or production of an organism
Red light and phytoplanktons
Phytoplankton absorb red light wavelengths which doesn’t extend far into the ocean so they stay at surface
Limiting factors bc it keeps primary productivity at surface
Gross and net primary productivity
Gross primary productivity= total amount of organic material created by producers
Net production ( gross productivity -respiration)
Compensation depth for photosynthesis
Gross photosynthesis is balanced by respiration
Water depth at which light is limited so that net photosynthesis =zero
- amount used= amount produced
Nutrient availability- phosphorus
Phytoplankton cant reproduce without it
Nutrient availability- nitrogen
Needed for nitrogen fixation
Supports photosynthesis, aquatic plant growth and protein synthesis
Nutrient availability -nitrate
Increased abundance w depth bc of upwelling
Brings deep water nutrients to surface
Nutrients- Redfield ratio
Nutrient concentrations in tissue of phytoplankton
106 carbon: 16 nitrogen: 1 phosphorus
Why are conditions optimal with 16:1 ration of N:P
Organic processes tend to control proportions of these elements in the water
ex. denitrification and nitrogen fixation by diazotrophs
Nutrient availability- Limiting factor
Can be too much or too little of nutrients (ex. N, P, Fe)
Eutrophication
Excessive loading of water w nutrients
ex. N and P
Effects of eutrophication
Increased biomass production
Increased O2 consumption and O2depletion
Algal blooms lead to hypoxic conditions and creates dead zones
Impacts of eutrophication
Food security
Ecosystem health
Disruptions in tourism
Fisheries and health industries
Iron (Fe)
Essential micronutrient; controls phytoplankton productivity
Iron limitation
HNLC
High nutrient, low chlorophyll areas but bioavailable Fe is scarce
Why is iron low in seawater?
Limiting nutrient
High reactivity of Fe2+ w O, so less Fe2+
Low solubility of Fe3+
Sources of Fe
Hydrothermal activity releases Fe to be upwelled
Dust
Carbon dioxide removal (CDR) technique
Artificially add Fe to the ocean’s surface to stimulate growth of phytoplankton which capture CO2
Will CDR work?
Wont be able to make enough phytoplankton
Over oxygenation creating dead zones
Direction of energy flow in marine ecosystems
Unidirectional
Producers
Autotrophic
Consumers
Heterotrophic; herbivores, carnivores, omnivores
Decomposers
Break down organic compounds
Energy flow in marine ecosystems
Energy transferred up to higher trophic levels
Primary producer- primary consumer- secondary consumer- tertiary consumer
Microscopic algae- Phytoplankton
Autotrophic- create glucose through photosynthesis
Occupy the euphotic zone
90-96% of surface ocean’s carbohydrate
What are the types of Phytoplankton- microscopic algae
Coccolithophores
Diatoms
Dinoflagellates
Coccolithophores
Moderate to low nutrient conditions
Tend to live in waters that are brightly lit, warm
Phytoplankton blooms
Exponential growth, reproduce asexually
Seasonal (bloom in spring and fall) and depend on latitude (higher)
Factors:
- Favourable winds and currents
- Overfeeding
- High water conditions
Dinoflagellates
Flagella: allow organism to adjust its orientation and vertical position in the water to obtain best light and nutrients
-Bioluminescent
- explosive growth causes red tides and harmful algal blooms
Where are phytoplankton?
Phytoplankton distribution corresponds to nutrient distribution in the water (upwelling areas)
Phytoplankton- Marine cyanobacteria
Smallest known photosynthesizers (Prochlorococcus)
Nutrient poor water (oligotrophic)
Macroscopic algae (seaweed)
Unicellular/ multicellular algae (not plants)
- photosynthesize
- diverse shape and size
- non-vascular
-dont grow below euphotic zone, can thrive in shallow water
Limiting factors of algae
Temp
Nutrient supply
Substrate
Light
Green seaweed- Chlorophyta
Intertidal, shallow water
Red seaweed- Rhodophyta
Most abundant
Widely distributed
Attached to substrate or encrusting
Brown seaweed- Phaeophyta
ex. rock weed and kelp
Marine angiosperms
Plants that reproduce w flowers and seeds
Sea grasses and mangroves
Autotrophic, vascular plants (hydrophytes, macrophytes)
Mangroves
Trees that grow in water
Grow in intertidal zone
Lower latitudes (dont like cold)
Can expel salt
**kelp and mangroves never in same place
Chemosynthesis
Conversion of one or more C-containing molecules into organic matter
Oxidation of inorganic compounds as a source of energy
No light -aphotic zone
Who performs chemosynthesis?
Deep ocean or hydrothermal vent communities
ex. gutless giant tube worms have symbiotic relationship w bacteria
ex. yeti crabs
Intertidal community
Area above water at low tide and underwater at high tide
Who lives in the intertidal community?
Invertebrates (benthic)- The molluscs
Gastropods, bivalves, cephalopods
Molluscs- gastropods (snails)
Periwinkles
Limpets
Dog whelks
Arthropods
Lobster, crabs, shrimp, barnacles
Arthropods - Barnacles
Cementers
Sessile suspension feeders (use cirri)
Stalkless- acorn barnacles
Stalked- goose barnacles
Types of barnacles
Semibalanus (light colour)- lower intertidal, long life, high mortality
Chthamalus (dark colour)- upper intertidal, fast growing, short life)
Competition of barnacles
“Competitive dominance”
Semibalanus outcompetes chthamalus by crowding or smothering
Chthamalus occupy higher tide levels resistant to dessication
Echinoderms
Sea stars and urchins
Cniadaria
Sea anemones
Difficulties of rocky intertidal communities
- Rapid temp changes
- Dessication
- Salinity changes
- Moving substrate
- Wave shock
- Exposure to marine and terrestrial predators
Ways to combat dessication
Hide in low lying area
Clam up to preserve moisture
Protect body by covering w shells
Lose an arm (starfish)
Ways to combat wave shock
Well anchored
Find shelter
Wedge in cracks
How do sea anemones combat wave shock?
Can adjust height based on wave action
ex. shorter in high wave activity
Why live in rocky intertidal communities?
Abundant food
Many nutrients
Abundant dissolved gases
Numerous places to live
Biotic community
Assemblage of organisms that live together within some definable area or habitat
Ecosystem
Biotic plus abiotic community- organisms exchange energy
