EEMB 142A Exam 1 Study Guide.docx

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University of California - Santa Barbara
Ecology, Evolution & Marine Biology

I Marine Biodiversity: Theory and Process Two kinds of Populations i)Demographically closed- only changing size because of local births and deaths ii) Demographically open- local births and deaths plus movement of individuals Marine populations are usually open systems  Typical life cycle in a marine community  Larvae(planktonic dispersal)  new recruits(settlement & metamorphosis)  adult(growth and maturity) Metapopulation structure that aids in the maintenance of biodiversity a) Marine Species Diversity (2 components) 1. Species Richness- number of different species present 2. Species Evenness- distribution of relative abundance among the species  What factors influence the number of species in a marine community?  Why do some marine communities have more species than others?  Depends on the influence of interspecific competition  Highly competitive species should drive less competitive species to extinction  Interspecific competition tends to act to reduce species diversity  Factors preventing superior competitors from excluding inferior ones help maintain diversity Niche theory  Niche- set of all environmental features within which a species can survive, grow and reproduce. Dimensions can be anything –depth, temperature, salinity, diet etc  Niche breadth- range of conditions within which a species can survive and reproduce. Generalists have large ranges and specialist and specific ranges  Niche overlap- degree to which different species require same features  Why do some communities have more species than others? 1. Greater range of resources- range depends on structural complexity, productivity, space etc. 2. More species if species present are more specialized- specialization influenced by environmental fluctuations an harshness 3. More species if overlap can be greater b)Evolutionary Process i)Niche Diversification  Co-ocurring species differ enough in niche requirements to preclude competitive exclusion  Species are more specialized  Reduce niche breadth and overlap c) Ecological Processes i)Involving Biotic Interactions Interspecific Competition  Species compete for resources (space, food, light)  Dominant competitors use resources faster, more efficiently, prevent access to resource by other competitors  Tends to reduce diversity via competitive exclusion Predation (maintains diversity in two ways)  Keystone Predation  A predator preferentially consumes competitive dominant species and frees resources for weaker competitors  EX: starfish prey on mussels and free up mussel beds for barnacles  Frequency-dependent Predation  Predator eats most common species  Typically no single species remains the most common indefinitely Circular Competitive Networks  Competitive abilities need not be hierarchical  No competitive dominant  Not common Mutualism  Different species benefit from close association  Obligate or facultative  Can keep one or both ii) Not Involving Biotic Interactions Intermediate Disturbance Hypothesis  Low disturbance= low diversity; strong competitors(K-selected species) dominate  High disturbance= low diversity; strong colonizers(r-selected species) dominate  Intermediate disturbance= high diversity; reduces abundance of competitive dominant, freeing resources for inferior competitors. Coexistence of r and K selected species. Settlement in Open Populations  Equal Chance (Lottery) Hypothesis  Limited space but species competitively equal  First to settle able to retain spot (ie. Not excluded)  Larvae of different species have equal chance of settling to an open spot (ie. A lottery)  Recruitment in Limitation  Supply of individuals of any species is low, no one species dominates (too few settlers to use up all resources)  Resources not in short supply, means competition is not strong. No exclusion.  Storage Effect(Lottery)  Settlement of new recruits fluctuate greatly  Periodic high recruitment can result in persistence  Finite rate of cohort extinction  Larger the settlement cohort, longer the time to extinction II Marine Habitats-2 realms a) Benthic Epibenthic- organisms on/above bottom  Sessile- attached firmly to surface  Mobile- capable of locomotion Infauna – organisms below sediment surface(categorized by size)  Macrofauna: >0.5mm  Meiofauna: 0.062-0.5mm(interstitial organisms-live in the water between sand grains)  Microfauna: <0.062mm i)Intertidal A. Characteristics  Light levels: very high. Except went turbid(e.g. estuaries)  Environmental conditions: extreme. Turbulence, salinity, temperate, anoxia, desiccation  Structural heterogeneity: high(rocky reef) to low(beach)  Primary productivity: High. Light + nutrients (upwelling, runoff), much benthic algae(rocky shores), high planktonic input B. Fish Species Richness  Rocky shores: moderate  Sandy beaches: low  Estuaries: low to moderate(nursery habitat) C. Adaptations  Morphology- body plans and coloration provide protection from predators, turbulence, and dessication  Small body size  Often elongate  Depressed or compressed  Highly cryptic  Physiology (eury= broad)  Eurythermal  Euryhaline  Tolerate desiccation and anoxia  Life History  Reproduction  Reefs: benthic(moist area and stable substrate) or pelagic eggs  Soft bottoms: mostly pelagic eggs(except grunion)  Both: pelagic larvae  Behavior: sedentary: active at high tide  Diets: small crustaceans, worms  Sensory Mechanism : reliance on vision ii) Subtidal  Continental shelf  Bathyal- shelf break to 4C  Abyssal- 4C to bottom  Hadal- trenches > 6000m Temperate reefs A. Characteristics  Light levels: high. Declines with depth, turbidity and shading  Environmental conditions: moderate but turbulent  Structural heterogeneity: high(rocks and algae)  Primary productivity: high B. Fish Species Richness: moderately high C. Adaptations  Morphology  Compressed body with large fins for maneuverability or elongate body for shelter in holes  Large mouths to eat large prey  Swim bladder(buoyancy)  Often cryptic(avoid predators and ambush prey)  Physiology(steno-narrow, less tolerant)  Stenothermal  Stenohaline  Low tolerance to desiccation and anoxia  Life History  Reproduction  Benthic or pelagic eggs  Pelagic larvae  Behavior: sedentary and active day or night  Diets; small crustaceans or fishes; some planktivores and herbivores  Sensory Mechanism: reliance on vision Tropical reefs A. Characteristics  Light levels: high  Environmental conditions: very benign  Structural heterogeneity: high(hard and soft coral)  Primary productivity: high(despite low nutrient and low planktonic input) B. Fish Species Richness: extremely high C. Adaptations  Morphology- every shape and color imaginable  Protection from predators: armor, spines/spikes, poisons, warning coloration, crypsis  Physiology- same as temperate + toxins  Life History  Reproduction- same as temperate, pelagic larvae  Behavior- same as temperate + complex social systems  Diets: crustaceans or fishes; many planktivores and herbivores  Sensory Mechanism : reliance on vision Soft Bottoms( unconsolidated sediments) A. Characteristics  Light levels: low and often turbid  Environmental conditions: benign  Structural heterogeneity: low except in seagrass beds  Primary productivity: moderate( high in estuaries and seagrass beds) B. Fish Species Richness : low because of low structural heterogeneity and primary production C. Adaptations  Morphology  Body size small to large  Compressed or depressed  Eyes on top of head  Subterminal mouth  cryptic  Physiology- same as rocky reefs except reduced or no swim bladder  Life History  Reproduction; broadcast spawners and live bearers  Behavior: larger home ranges than on rocky reefs  Diets: infauna, fish, detritus  Sensory Mechanism: barbels(detect prey), electro-reception, olfaction b)Pelagic Nekton- animals capable of moving against flowing water Plankton- organisms incapable of moving against water flow  Types  Phytoplankton- free-floating organisms capable of photosynthesis  Zooplankton- free-floating animals with limited locomotion  Bacterioplankton- free-floating bacteria and blue-green algae  Viroplankton – free-floating viruses  Life History  Holoplankton- spend entire life cycle as plankton  Meroplankton- spend only part of life cycle in plankton stage; usually larvae adults of benthic realm i)Epipelagic(photic)- surface to 100-200m. bottom set by a biological process(photosynthesis). At lower limit net productivity=0. Determined by light penetration. A. Characteristics  Light levels: high(declines with depth)  Environmental conditions: deep  Structural heterogeneity: none  Primary productivity: variable, higher near coasts(nutrients from runoff and upwelling) B. Fish Species Richness: low C. Adaptations  Morphology  Body size small to very large  Body form: fusiform(move constantly)  High aspect ratio fins  Heterocercal caudal fin  Swim bladder and fatty liver(buoyancy)  Counter-shaded; silvery  Physiology  Counter-current blood circiulation  Life History  Reproduction: broadcast spawners or live bearers  Behavior: speed, schooling to avoid being eaten  Diets: simple food webs, planktivores and predators  Sensory Mechanism: electroreception and olfaction  Mesopelagic(Deep Sea)- lower limit is at 10C(700-1000m)  Bathypelagic(Deep Sea)- lower limit is at 4C(2000-4000m) ii) Abyssopelagic- all the way to the bottom iii) Hadalpelagic- trenches > 6000m *Deep Sea A. Characteristics  Light levels: dark  Environmental conditions: expansive, high pressure  Structural heterogeneity: none to little  Primary productivity: very low B. Fish Species Richness: very low C. Adaptations  Morphology  Body size and shape small and thin, short or elongate  Eyes large(meso-) or small(bathy-) pointed upwards  Mouth is large  Extendible stomach  Physiology  Low muscle, high water content  Enzyme systems pressure adapted  Life History  Reproduction: poorly known. In some species the male is very small and parasitic on the female  Behavior; vertical migration(mesopelagic only)  Diets: shrimp, each other, rain of detritus  Sensory Mechanism: photophores (signaling, countershading), lateral line(sense motion) III Kelp Forest Ecology Kelps are a foundation species(primary producer that defines a community by providing both food and habitat) Thrive in the cold water on the western margins of continents where there is a lot of upwelling of nutrients 27 genera of kelp a) Kelp Morphology i)Kelp are protists- their holdfasts are not analogous to roots because they have no specialized tissue for nutrient absorption Giant kelps- possess gas-filled floats. Extend through the water column to produce a canopy at the sea surface. Stipate kelps- possess a thick rigid stipe and small holdfast. Extend up to 2m off the bottom to produce a subsurface canopy b)Kelp Forest Community Understory algae grow in the shadow of giant kelp and form an important habitat  Different species coexist to produce multiple vegetation layers that compete for light and space Sessile filter feeding invertebrates also occupy space on the bottom in kelp forests ii) Biological Interactions  Shading by giant kelp affects competition between understory algae and sessile invertebrates  Giant kelp overshades understory algae which compete for space with sessile invertebrates(giant kelp has indirect positive effect on sessile invertebrates) Mobile Invertebrates- kelp consumers  Sessile invertebrates and understory algae are important food sources Kelp Forest Fishes- mostly predators Mammals and Birds- seagulls, sea otters, sea lions, grey whales iii) Net Primary Production- the amount of plant matter produced per unit area of the earth‟s surface per unit time. Fundamental to life on earth as it influences virtually all ecosystem processes. NPP is the product of the density of actively growing plant mass and its rate of increase due to recruitment and growth  High growth rates lead to high net primary production  Low standing biomass that turns over~ 6times per year  Two distinct pathways lead to changes in NPP  Disturbance and herbivory  Resource supply and environmental conditions Fate of Kelp Production  ~5% consumed within the forest  Active grazing on living plants  Passive feeding on large and small kelp detritus  Export to beaches  ~95% exported out of the forest to adjacent ecosystems.  Greatest export occurs during large wave events  Giant kelp subsidizes the foodwebs of sandy beach ecosystems  Export to deep sea  Accounts for up to 80% of the particulate carbon reacting the deep sea floor and 60% of the diet of sea urchins that live there iv) Abiotic influences Light, nutrients, hard bottom, temperature, water motion Waves and nutrients explain variation in the dynamics of giant kelp in the SB Channel v) Biotic influences Competition, grazing and predators Environmental drivers  Changes in abundance causing shifts in community structure  Forested(complex)  Deforested(simple structure) AKA urchin barrens - predator decline, herbivore increase. Large waves that remove kelp. Warm, nutrient poor conditions  Deforested(simple structure)  Forested(complex)- predator increase, herbivore decline, large waves that remove grazers. Cool, nutrient-rich conditions  Changes in structure vi) Ecosystem services Provisioning Services- fisheries, aquaculture, pharmaceuticals, bio
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