Download Biotic Factors The Biotic Factors

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Biotic Factors
= living components that shape an ecosystem
The Biotic Factors
1. Marine Ecology
-  populations
-  communities
-  ecosystems
2. Strategies
-  succession
3. Interactions
-  symbioses
-  competition
-  predation
-  biofouling
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Marine Ecology
Populations
= groups of individuals that occupy an area, evaluated in terms
of their age structure, survival, germination and mortality
(death)
Longevity
1.  Annual
< 1 year
2.  Biannual
2 year
3.  Perannial
> 2 years
4.  Pseudo-perannial > 2 years, part of year
in reduced stage
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Survival (Mortality)
ex. Macrocystis
pyrifera
= giant kelp
up to 95% of
sporophytes do
not survive
following
Communities
= populations of species that coexist and interact in a
particular habitat
Continuous community
Alaria fistulosa
Laminaria sp.
Agarum clathratum
benthic reds and green algae
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Communities
= niches within communities
example: Gulf of Mexico (seagrass beds)
Thalassia testudinum
large portion of seagrass
beds dominated by
Thalassia
Halodule and Syringodium
generally found towards
edge of seagrass beds
Thalassia only =
fundamental niche
Halodule
wrightii
Syringodium
filiforme
Mix = partial niche
Ecosystems
= community of living organisms (not only including algae) in
conjunction with abiotic components of their environments
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Productivity of Primary Producers
Morphology!
Construction!
Examples!
Blades,
filaments!
thin, 1-few cells thick, Ulva, Dictyota!
soft, filamentous,
Ceramium,
delicate!
Cladophora!
Coarsely
branched!
Erect, many cells
thick, fleshy to wiry!
Gracilaria,
Codium!
Thick or
leathery!
Branches or blades
thick, corticated,
rubbery!
Laminaria, Fucus!
Flexible,
calcareous!
Calcified but jointed,
hard surface!
Corallina,
Halimeda!
Crustose!
Calcified or not,
encrusting, prostrate!
Petrocelis,
Clathromorphum!
Pictures!
Ecological Strategies
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Succession
Communities are not static
Succession
In marine environments:
I. Pioneer
= usually annuals, rapid growth,
high reproduction
II. Stable
= usually perennials, higher
species diversity
Disturbance through disasters
and catastrophes
Examples of Succession
Seagrass Beds (i.e. Gulf of Mexico)
Pioneers!
Halimeda, Udotea,
Penicillius, Caulerpa!
Stables!
rhizophytic,
add organic
matter!
Syringodium,!
Thalassia!
seagrasses grow
on improved
sediments!
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Examples of Succession
Coral Reef Communities (i.e. Hawaii)
Pioneers!
Stables!
Enteromorpha,
Ectocarpus!
Green, brown
filamentous!
Centroceras,
Taenioma!
Thin, branched
alge then
encrusting!
Examples of Succession
Kelp forests (i.e. Alaska )
Pioneers!
Nerocystis, Alaria!
Stables!
Mixed kelp
canopy!
Costaria, Laminaria! understory!
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Examples of Succession
Rocky shores (i.e. New England )
Pioneers!
Ulva!
Stables!
Early, productive, thin
green algae!
Fucus,
Ascophyllum!
Tougher, may be
exposed to dessication!
Characteristics of pioneers and
late successional seaweeds
Early-state (Pioneer)
species!
Late-stage (Mature) species!
No seasonally controlled
reproduction!
Seasonally controlled
reproduction!
Disturbed locations!
Replacement !
Annuals, short life histories!
Perennials, long life histories,
complex lifecycles!
Simple construction, high
productivity, high surfacevolume ratio!
Complex construction, low
productivity, low surface areavolume ratio!
Escape grazing!
Slow growth, defenses!
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Biological Interactions
…. best known are plant-animal interactions
Symbiosis
= may be of several kinds, parasitism, mutualism, commensalism
(epiphytes)
comparable to epiphytic vascular on nonvascular plants =
tropical rainforest
Polysiphonia lanosa on Ascophyllum nodosum
Notheia anomala on Hormosira banksia
Smithora naiadum on Zostera marina
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Competition
= active demand by 2 or more organisms for a resource,
exploitative or interference
zonation rocky shores
mangroves
shading in Gulf of Mexico
Predation
= biological interaction, predator (generally an animal)
consumes a prey item (plant or animal) to sustain themselves
changes in predator levels can lead to chain reactions:
gulls and Strongylocentrotus purpuratus
may change succession
extreme grazing is observed in many environments, exception
are seagrass beds
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Biofouling
= similar to epiphytism but growth on anthropogenic structures,
i.e. human effects
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