Marine Ecology Species – a group of similar organisms whose members interbreed and produce viable...
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![Page 1: Marine Ecology Species – a group of similar organisms whose members interbreed and produce viable offspring. Population – members of the same species that.](https://reader034.fdocuments.us/reader034/viewer/2022051517/56649e9c5503460f94b9d131/html5/thumbnails/1.jpg)
Marine Ecology
• Species – a group of similar organisms whose members interbreed and produce viable offspring.
• Population – members of the same species that live together in the same area at the same time.
• Community – all the populations of different species that live and interact together within an area at the same time.
• Ecosystem – a community together with its physical (abiotic) environment.
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How Populations Work in a Community
• Population growth– More individuals– Birth rates > death rates– Decrease in resources
• Food, nutrients, space• Until the available
resources can no longer support more growth
– Lag phase• Period of relatively slow
growth
– Post-lag phase…• Linear, Exponential, or
logistic growth
• Renewable resources: replenished by natural processes at a rate comparable or faster than its rate of consumption.
– solar radiation, oxygen, tides, food, water, and winds
• Non renewable:– used at a rate greater than the
environment's capacity to replenish them
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• Linear growth– Constant numerical
increase; constant slope– Doubling occurs relatively
slowly
• Exponential growth– Growing numerical
increase; “J” curve– Doubling occurs rapidly– Occurs with no limits to
growth– e.g fig. 10.2b
(dinoflagellates…much like these bacteria)
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Exponential growth until?
• Environmental resistance– Limiting factors
• Supply restricts the growth of a population (e.g. food)
• Logistic growth– Converts a “J” curve to an
“S” curve (fig. 10.4)– Sets carrying capacity
• Population size sustained by available resources
…as resources decrease, competition increases
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Organisms interact within a community
• competition, predation, symbiosis
• Competition– organisms compete for
same resources• Intraspecific (within same
species)
• Interspecific (between species)
– Superior competitor wins• Outcompeting to the point
of eliminating the other = competitive exclusion
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Sharing to avoid exclusion
• Resource partitioning– Specializing in part of
the resources• slightly different food• different spaces• different times
– Dividing the resources– Lends to smaller
populations of a single species
• Giving up some of the resources is limiting
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Symbiosis (living together)
• Mutualism– Both organisms benefit
• “Cleaner” shrimp & fish (facultative)
• Zooxanthellae & Cnidaria (obligate)
• Commensalism– One organism benefits w/o
affecting the other• E.g. whale barnacles
(shelter & food)
• Parasitism– One organism benefits at
the expense of the other• E.g. intestinal worms(Nematodes in fin whale gut)• Ectoparasitic isopods
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Marine communities• Lifestyles
– Benthic (bottoms)– Pelagic (open-water)
• Plankton: drifting in the currents
– Phytoplankton» autotrophic
– Zooplankton» Heterotrophic
– Nekton: free swimming
• Environment/structure– Transitional: land & sea– Depth– Topography Fig. 10.12
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Flow of energy w/in ecosystem• How energy passes through the
ecosystem– one way flow (Fig. 10.13)
• Producers– autotrophs (self nourishment) that
use simple inorganic molecules to make complex organic molecules (photosynthesize)
• Consumers– heterotrophs (different
nourishment) that eat producers to gain energy, cannot gain energy just from simple inorganics
• Decomposers– heterotrophs that break down
dead material to make energy• At each level some heat is given
off or lost– energy that is unavailable to the
next level
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Most food webs are complex… this
Antarctic example is considered simple:
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Trophic levels
• Steps of energy transfer
• Each level relies on the level(s) below
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Energy efficiency
• 10% E (ave) passes to next level– Only a small amount
goes toward actual growth
• Sustains fewer organisms
• 10 times more biomass is required to sustain the level above
Fig 10.16
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Primary productivity
• Amount of carbon converted (fixed) from CO2 to usable organics– Gross primary production– Net primary production
• Leftover after respiration
gC/m2/day
gC/m2/year
• Can also measure O2 production via photosynthesis
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• Productivity depends on:– Light– Location– Depth– Abundance of
organics– Etc…
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Carbon cycle
• CO2 is highly soluble– 50 times >
atmosphere
• Converted by photosynthesis
• Broken down by respiration– Consumers,
decomposers, & producers
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Homework (due 4/30/08)
• Review pgs. 231-240
• Describe the human impact of burning fossil fuels & increasing the amount of CO2 in the atmosphere
• What does this do to global temperatures?
• How does this impact our oceans?
• How does this impact the marine trophic levels?