Winds displace ocean water off the west coast of North and South America causing upwelling cold nutrient rich water pulled up to replace displaced surface water California summer winds blow from the north curve west creating upwelling along coast enhancing nutrient supply to phytoplankton Winter winds blow from the south curve east favoring downwelling along the coast Habitats resources conditions and niches upwelling Rich fisheries 1 Rain shadows and Mediterranean climates e g California if the land is warmer than the ocean moisture in marine air is not dropped until adiabatic cooling over mountains summer drought 2 Rain forest Alpine lakes Desert If land cooler than ocean moisture is dropped winter rains Rain shadow Eastern Sierra 3 Rain shadow Eastern Sierra 4 Water ends up in lakes rivers or ground water Seasonal mixing regimes water is densest at 4oC winter and summer stratification spring and fall overturn Lakes that experience seasonal freezing Thermocline stratum of rapid temperature change Can separate oxygenated from hypoxic habitat Mixing replenishes nutrients for algae in photic zone 5 6 Eutrophic river lake estuary nutrient rich likely to produce noxious or harmful algal blooms cyanobacteria toxic dinoflagellates Mesotrophic intermediate nutrient concentrations Oligotrophic low nutrient concentrations very clear water good water quality for humans and fish River networks Downstream concentrative fluxes of water sediment solutes detritus and passive organisms Upstream and upslope dispersive backflows of mobile organisms Systematic downstream increases in discharge channel width solar radiation Sediment size decreases and disturbance from bed scour is more frequent Confluence nodes pulses of enrichment adjacency of contrasting habitats refuges David Schindler s experimental lakes Easier for wind to stir nutrients in shallow basin making such lakes vulnerable to eutrophication 7 8 Energy carbon sources change downstream Terrestrial detrital carbon e g dead leaves that fall into streams Attached algae Fine particulate detritus and phytoplankton 9 10 Detritus dead organic matter Cover down drainage networks Headwaters woody debris forest cover Estuary where rivers empty into oceans fresh water 0 salt meets salt water 3 salt tidal prisms with heavier salty water underneath A 5 km2 Meandering middle reaches clean gravel beds hyporheic under the stream bed habitat undercut rooted bank vegetation off river habitat Lowland floodplain rivers floodplain marshes or forests off channel water bodies Important nurseries for offshore fisheries 11 Tidal prism wedge of fresh water overlies denser salt water 12 Intertidal vertical zonation Vertical and onshore offshore zonation Abiotic stress Biotic interactions 13 Neritic nearshore subtidal Plankton passive drifters Nekton active swimmers Benthos life on substrate or bed of sea lake spring or rivers and streams Benthic infauna 14 Pelagic Offshore beyond Continental Shelf Bill Hamner zooplankton phytoplankton Resources conditions and the fundamental niche What determines the distribution and abundance of species In part their tolerance of conditions and their need for certain resources condition abiotic environmental factor that varies in space and time and affects the performance of organism resource all things consumed used up by organisms space nutrients water prey holes for refuge etc 16 Structure Cover Food 15 17 How do conditions and resources influence the distribution and abundance of organisms 18 Macan s filter continued Macan s filter similar to Fig 50 6 Campbell If a species is absent from a habitat is it because of 1 Dispersal Yes hasn t arrived yet barriers insufficient time No propagules have arrived but don t persist propagule a dispersing unit capable of establishing a new population e g one asexual spore Adam and Eve a pregnant female fish or a fragment of a plant that can reproduce vegetatively 2 Behavior Yes colonists avoid habitat No colonists select habitat but don t persist 3 Abiotic factors Yes temperature salinity pH moisture conditions etc are outside the range that the species can tolerate No abiotic conditions are tolerable 4 Biotic interactions Yes species is excluded by predators pathogens competitors or the lack of prey resources or mutualists No 19 20 Example Africanized bees may have been selected in tropics to withstand or avoid predation by army ants aggressive defensive stinging bees disperse at small colony size European bees shiver to warm hives during winter Will small colony size limit the northward spread of Africanized bees Don t build up large enough colonies to 22 warm hive by collective shivering 21 Performance is generally nonlinear across a range of intensities of an abiotic condition some is good more is better even more is very bad A resource can become a condition at high or low levels e g light Water Performance of species Distributions of organisms determined by cooccurrence of a number of critical potentially limiting resources and conditions Reproduction Non interactive Interactive Growth grows Nitrogen s cold g r r g s hot Condition e g temperature Survival dies 23 Phosphorus grows Light dies Nitrogen 24 Niche Range of conditions resource levels and densities of other species within which an organism or species can survive and reproduce persist over time An N dimensional hypervolume hypervolume if each condition resource or other species seen as a dimension Hutchinson Stickleback Fundamental Niche Salt 30 ppt Tolerates more salinity at colder temperatures Salinity Fundamental Niche the largest niche in which a species could persist in the absence of adverse interactions with other species Realized Niche the generally smaller niche volume actually occupied by a species in the presence of interspecific interactions Stickleback survives grows Fresh 0 ppt warm cold Temperature 25 26 Osmosis diffusion of water from lower to higher salinity gradients across semi permeable membranes Stickleback Fundamental Niche Salt 30 ppt Hypothesis H gills must pump more water to extract oxygen at warm temperatures higher metabolic rate lower oxygen concentration in water increasing osmoregulatory stress Salinity Tolerates warmer temperatures at lower salinity why Cell walls plants Saltier outside Saltier inside Cell membranes animals Fresh 0 ppt warm cold Temperature 27 28 Prediction Salt 30 ppt Observation present Salinity Realized stickleback niche if gill parasite is present Without parasite
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