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Transcript
8/11/14 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 1 8/11/14 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 2 8/11/14 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 3 8/11/14 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 4 8/11/14 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 5 8/11/14 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! 6 8/11/14 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! 7 8/11/14 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! 8 8/11/14 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 9 8/11/14 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 10 8/11/14 Biofouling = similar to epiphytism but growth on anthropogenic structures, i.e. human effects 11
