L2 - Introduction to Marine Ecology Flashcards
What is marine ecology?
Scientific method
Scales of study
Major divisions of the marine environment
Comparison of marine & terrestrial ecosystems
“…the study of the principles which govern temporal & spatial patterns for assemblages of organisms.” (Fenchel 1987)
“…the study of the relationship between organisms and their physical and biological environments.” (Ehrlich & Roughgarden 1987)
Intrinsic value
Why study ecology?
But what we tell the funding agencies is that …..
Effective management requires:
Knowledge about how ecosystems function
ie. What processes govern the spatial and temporal variability in organism abundance
Then (maybe)….
Isolate natural variability from anthropogenic disturbance
Prediction
Scientific method
Scales of Study: The Ecological Hierarchy
Biosphere > Ecosystem
(Global warming will impact Ecosystems through acidification, changing nutrient cycles)
Ecosystem > Community
Acidification and Nutrient cycle changes in the above cascades down to the:
Population
Individual
May affect population numbersd, restructure communities and alter the ecosystem
Biosphere
Interaction between environment and life on earth
Global carbon cycles, effects of climate change on biosphere
Dark green = photosynthesis and plant biomass
ocean bright colours represent phytoplankton biomass
annual cycle of biosphere breathing
Ecosystem
Assemblage of interdependent biological communities in a single geographic area
Boundaries set by researcher
Quantify environmental effects on energy flow
Not interested in individual performance
Interest is how nutrience and energy flows through system
example: oceanic ecosystem
interested in the relationship between how much solar energy inout from sun and how much primary production as a result.
Variations in cloud cover and solar radiance affecting the amount of fixed carbon
(not looking at how many individual species of phytoplankton)
The role of bacteria and decomposition and the regeneration of nutrience
LARGER SCALE QUESTIONS
ECO SYSTEM CONSTRAINTS ON PRODUCTION?
HOW DOES SOLAR RADIATION AFFECT FIXED CARBON?
CONSEQUENCES FOR HIGHER TROPHIC LEVELS?
Assemblage of interacting species
Studies focus on interspecific interactions
(most ecologists work at this scale)
Dropping down through the ecological heriechy the unit of scale becomes smaller and the focus and questions become different.
Interested in interactions between individuals
Predation (+ -)
Benefit for one and negative for prey
Parasitism (+ -)
Benefit for parasite and negative for host
Competition (+ - or - -)
Positive for winner (gain territory/food)
Negative for Loser
Or cost of interaction a negative for both participants if damage done
Territoriality (+ - or - -)
Winner positive
Loser negative
Neagtive for both if damage inflicted
Commensalism (+ 0)
an association between two organisms in which one benefits and the other derives neither benefit nor harm.
Mutualism (+ +)
Both positive effect for other
Community Studies
Address processes affecting species distribution and abundance (ie community composition)
Includes
Dispersal
Interspecific competition
Predation
Disease & parasitism
Disturbance
Facilitation
Example: Removing Grazing Community
-Green grass a result of opertunistic algae in the absence of grazers
Population
A group of individuals that are affected by the same environment and are relatively unconnected with other populations of the same species - A management unit.
Important in fisheries management as when we remove biomass or remove individuals from a population we’re adding mortality to a system.. If that mortality is not compensated through new individuals arriving through emmigration/immigration? or more critically through recuitment to that population then that population can crash and abundance will can down.
Individual
These studies are done at much smaller scales
- Physiologically independent from other organisms
- Studies at this scale are concern with organism growth & behavioura
Ecological cascade
Biosphere all the way to individual and we begin to think about top down affects which is occuring at the scale higher which cascades back down but there is also bottom up affects where individual performance (extra nutrience in system) may cause good recruitment years which affect populations in communities and eco systems.
TIERS ARE NOT ISOLATED FROM THOSE ABOVE AND BELOW IT, THEY ARE CONNECTED THROUGH THESE INTERFACES.
55 % of the pelagic environment by volume is deeper than 2000 m
80 % of the benthic environment by area is deeper than 2000 m
Ocean divided in two ways
Pelagic = Water Collumn
Benthic = Sea Bed
Epipelagic (first 200m)
- The depth of light penetration
- Where most of the primary production is occuring
- Average depth of ocean is 7000m deep, all the biomass in the ocean is supported by the top 100-200m of water where organic matter is being fixed
Mesopelagic (200-1000m)
Depth of permanent thermocline occurs. Where seperation of water in contact with atmosphere seasonally/regularly is seperated from the top of the atmosphere.
As we move near shore to offshore, envrionmental variability decreases (salinity, temp, nutrient availability)
The closer to land, the more terrestrial infuence and climatic variations
Intertidal zone = Extreme climatic variations
Offshore: Less environmental variability.
Deep ocean: Environmental variability decreases further
Surface area: Day night variance
The further and deeper you go.. the less environmental variance
Neritic = Near Shore
The distinction between these two points is generally made at the continental shelf where the water depth is at around 200m. This is where the seabed begins to get deeper very very quickly.
Neritic Zone: Water influenced by run off from the continent
(Fresh water from rivers, sediments, nutrience)
Lots of Primary Production occuring, way more productive than oceanic environment. Sub division made because of influence of terrestrial run off in the near shore environment.
Oceanic Zone
Sufficently far offshore where the effects of land run off don’t impact upon the ecology or systems that are working there.
Oceanic zones further sub divided by depths
(WILL NOT COME UP IN TEST)
Light & Temperature
Marine vs Terrestrial Ecosystems
Water provides buoyancy
Planktonic life forms, no need for structural components
Narrow temperature range
Dispersal medium for organisms, eggs & larvae
Universal solvent
Plants acquire nutrients directly from the water
Dilutes & disperses metabolic wastes & pollutants
Third habitat dimension (water column) supports many organisms not found on land
Water is wet air is dry!
Obvious statement
Water: wet
Air: dry
Fundamental shift in terms of the ammount of stuff you need to survive in that environment
Surviving in terrestrial very difficult
Surviving in water easier
High thermal capacity but low temperature range
Organisms don’t have to worry to much about heating
Number of higher animal taxa (endemic)
Marine Vs Terrestrial
Terrestrial
Primary production is dominated by large (carbon fixing) autotrophs
(trees, grasses, shrubs)
Consumed by large warm blooded herbivores
Consumed by large warm blooded predators
Marine
Predominantly based on microscopic autotrophs
(small phytoplankton)
Eaten my microscopic herbivores
(zoo plankton)
Eaten by Herring
Eaten by squid and higher order predators
Marine vs Terrestrial Production
Marine
- Primary production is carried out by small phytoplankton
- Phytolankton are high in protein
- Majority of production is readily consumed and digested by herbivores
- Primary production = 50-350 g C m-2 a-1
- P/B ratio = 100-300
- High secondary production (cold-blooded, buoyant fluid, high reproductive output)
Terrestrial
- Primary producers are large trees & grasses
- Terrestrial plants are high in carbohydrates & cellulose
- Most production enters the food chain via decomposition cycles
- Primary production = 0-3900 g C m-2 a-1
- P/B ratio = 0.5-2.0 a large fraction of production is used to maintain the high biomass
- Lower secondary production (warm blooded, gravity, parental care)
-Phytoplankton very high in protein
(They don’t need structual elements so just about all of their form is highly nutritional)
-Terrestiral plants high in carbohydrates and cellulose
(Alot of non-nutritional material for example in grasses and also in trees and shrubs such as bark)
Marine
Zooplankton cold blooded
Buoyant so little energy expenditure
High reproductive output
Terrestrial (herbivores)
Warm blooded
Gravity to fight (energy expenditure)
Parental care (energy expenditure)
Costs mean that energy can’t be cast up the food chain
Oceans contribute 35 % of the World’s plant production
but accounts for 80 % of the animal biomass production
Primary production turns over very fast and its highly nutritional and its going into animal production that has high reproductive output with low cost.
Although more carbon fixed in terrestrial systems, alot of carbon unavailable to the animal production as its being respired to support the structure and alot of it is indigestible and the animal production is warm blooded and its not using it for production and growth.
