Chapter 3: THE AQUATIC ENVIRONMENT 4) Cohesion – water mols tend to stick firmly to each other

- Water – 75-95% of the wt of all living cells -forces of attraction are same at all sides (at body of water)
- Ecosystems into 2: saltwater & freshwater -below the surface: mols of water are strongly attracted to one another
3.1 WATER CYCLES BET EARTH & ATMOSPHERE -above the surface: weaker attraction bet water mols & air
- Water/Hydrologic cycle – process bywhich water travels in a sequence -mols on the surface are drawn downward  results in a surface that is
from the air to Earth & returns to the atmosphere taut like an inflated balloon (surface tension)
- Solar radiation – heats the earth’s atmosphere & provides energy for -responsible for viscosity of water
evaporation of water
-driving force behind water cycle 5) High Viscosity – property of material that measures the force necessary to
- Precipitation – sets water cycle in motion separate the mols and allow an object to pass through the liquid
- Water vapour falls into precipitation -source of frictional resistance (100x greater than that of air) to objects
- Water falls on sail, bodies of water; some intercepted by vegetation, dead moving through water
organic matter on ground, &urban structures  interception – causes amts -an animal streamlined in reverse (w shirt rounded front & rapidly
of water to never infiltrate the ground & evaporate it back to atm tapering body) meets the least water resistance
- Surface runoff – overland flow; when excess water flows across surface due -high viscosity – due to greater density of water (860x greater than air)
to saturated soil during heavy rains -limits mobility of organisms
-concentrates into depressions & gullies -buoyancy – upward force exerted when a body submerged in water
-flow changes from sheet to channelized flow weighs less than the water it displaces
-85% of ppt because of low infiltration
- Groundwater – water entering the soil seeps down to an impervious layer 6) High Density – water experiences greater changes in pressure w depth
of clay or rock  water finds its way to springs & streams than does air
-streams – coalesce into rivers -pressure increases 1 atm for each 10m in depth
-rivers – coalesce into coast (transition from freshwater to marine) -proteins & biological membranes are affected by pressure

- Evaporation – through which water remaining on the surface of the ground 3.3 LIGHT VARIES W DEPTH
in the upper layers of the soil returns to the atmosphere - When light strikes surface of water, certain amt is reflected back to atm
-rate of evaporation – by how much water vapour is in the air relative to - Amount of light reflected depends on angle at which light strikes surface
the SVP (relative humidity) -lower angle, larger amount of light reflected
- Transpiration – evaporation of water from internal surfaces of leaves, -amt of light reflected vary diurnally & seasonally moving from equator to
stems poles
- Evapotranspiration – total amount of evaporating water from surfaces of - Amount of light entering the water surface is reduced by:
the ground & vegetation (surface evaporation + transpiration) • Suspended particles – intercept light & either absorb or scatter it
-scattering of light increases its path of travel through water & results in
- 1.4B km3 – total volume of water on earth (97% in oceans; 2% in polar ice further attenuation
caps & glaciers; 0.3% groundwater – 3rd largest active reservoir) • Water itself absorbs light – only 40% of shortwave rad reaches depth of
-111,000 Km3 of water falls as ppt 1m even in clear water
-71,000 km3 returned to atm as evapotranspiration -water absorbs more waveleingth than others
-40,000 km3 is carried as runoff by rivers 1) red & infrared – first absorbed; greater than 750nm; absorption
- Atmosphere – important in the global water cycle; reflected by the reduces solar energy by ½
turnover time of the 13 km3 atmospheric reservoir 2) yellow disappears in clear water; (3) green; (4) violet; (5) blue –
- Turnover time = size of reservoir / rate of output (flux out) penetrate deeper water; lost w increasing depth
- Changes in light influence the quantity and distribution of productivity
3.2 PHYSICAL PROPERTIES OF WATER (direct) & the vertical profile of temperature w water depth (indirect)
1) 2 H atoms joined to 1 O atom  asymmetrical binding - Lack of light in deeper waters = adaptations
- Polar covalent bond -shared e-; partial + towards H; partial - to O -organisms are silvery gray or deep black; lack pigment
- Weakly bonded to neighboring mols because of polarity -large eyes for light-gathering ability
- Tetrahedral – arrangement of molecules; angle bet H encourages this -bioluminescence – produce light thru chemical reactions
- Hydrogen Bonding – when H atoms act as connecting links; weak bonds
3.4 TEMPERATURE VARIES W WATER DEPTH
2) High specific heat – number of calories necessary to raise 1 gram of water - Surface temp – reflect the balance of incoming and outgoing radiation
1 degree Celsius - Temperature profile with depth may resemble the vertical profile of light as
-specific heat of water: defined as a value of 1 solar radiation is absorbed in the vertical water column
-water can store large quantities of heat with a small rise in temp - Sunlight absorbed in the surface waters  heats up
-as a result, great quantities of heat must be absorbed before temp rises - Winds & surface waves – mix surface waters; distributing the heat vertically
just 1’C - Decrease in water temp with depth will lag the decline in solar radiation
-warm up slowly in spring; cool slowly in fall  prevent seasonal - Thermocline – region of vertical depth profile where temp declines most
fluctuations rapidly
-for thermal regulation of organisms -depth will depend on input of solar radiation to surface water
-large quantities of heat energy are required to change its state between -below thermocline: water temp continue to fall but at slower rate
S, L, G phases -temperature zonation with depth (result)
-latent heat – energy released/absorbed in transforming water from one • Epilimnion – upper layer of warm, lighter, less dense water
state to another • Thermocline – middle; zone of rapid temp change
-536 calories – to overcome attraction bet molecules and convert 1 g of -density at thermocline serves as physical barrier that prevents mixing of
water at 100’C into vapour upper & lower layers
• Hypolimnion – deeper layer of cold, denser water
3) Lattice arrangement – gives water a peculiar density-temperature
relationship - Seasonal changes in input of solar radiation = seasonal changes in vertical
-liquid is denser when cooled profile of temperature in aquatic env
-pure water becomes denser til cooled at 4’C - Thermocline – permanent feature of tropical waters due to constant solar
-cooling below 4’C results in decrease in density radiation input
-0’C – freezing occurs; lattice structure is complete
-oxygen atoms is connected to 4 other oxygen atoms by means of H atoms
 lattice w large open spaces (decrease density)

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- Temperate zone: distinct thermocline during summer 3.7 ACIDITY HAS A WIDESPREAD INFLUENCE ON AQUATIC ENVI.
-by fall: air temp & light decrease, surface water of epilimnion cools - Water has a considerable capacity to absorb CO2
-water becomes denser & sinks (displacing the warmer water below to the - CO2 reacts with H2O to produce carbonic acid (H2CO3)
surface where it cools in turn) - Carbonic acid dissociates into Hydrogen ion & Bicarbonate ion
-winds – mix the vertical profile to greater depths  continues until temp - Bicarbonate may dissociate into another Hydrogen ion & carbonate ion
is uniform throughout the basin
-Fall turnover – process of vertical circulation stirred by wind CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3- ↔ H+ + CO32-
- Winter: surface water cools to below 4’C lighter & remains on surface - Carbon-Dioxide Carbonic acid- Bicarbonate System- tend to maintain
-if cold enough, water freezes equilibrium
-warmest place in the lake is on bottom  Function as buffer to keep pH of water w/in narrow range
- Spring: breakup of ice and heating of surface water w increasing inputs of  Absorb H+ in the water when they are in excess = bicarbonates &
solar radiation causes water to stratify carbonic acid
 Produce H+ ions when short in supply = carbonate & bicarbonate ions
- Thermocline (in bodies of water w/o stratification) – descends during pH- measurement of acidity & alkalinity = -log10 [ conc’t of H+]
periods of turnover & does not appear at all - Acidity- measures abundance of H+ in a solution (pH < 7)
- Temp of a flowing body of water – variable  Affect physiological processes of organisms & influence conc’t of toxic
- Small, shallow streams – warm & cool with the seasons heavy metals in water
 Most organisms cannot survive & reproduce if pH ↓ 4.5 (w/ high
3.5 WATER FUNCTIONS AS A SOLVENT concentrations of aluminium)
- Solution – liquid that is a homologous mixture of 2/more substances  Aluminum: highly toxic, insoluble when pH is neutral or basic
- Solvent – dissolving agent - Alkaline- large no. of OH- & < H+ (pH >7)
- Solute – substance dissolved  High pH: more CO2 is present as CO32-
- Aqueous solution – solution in wc water is the solvent  waters in watersheds: w/ limestone (CaCO3), acid sandstone & granite
- Provides fluid that dissolves & transports molecules of nutrients & waste (w/ Na, K, & Ca  pH = 7.5-8.4)
products; help regulate temp; preserves chemical equilibrium - Ratio: 1H+: 1OH-
- Solvent ability due to asymmetric bonding of H to O - Neutral solution: pH= [-log(10-7)] = 7
-Permanent dipole: permanent positive charge on 1 side & permanent Ex: gain of H+ ions to 10-6 moles = decrease of OH- ions to 10-8
negative charge on another pH of solution =6
- Ions – electrically charged atoms or groups of atoms  Most CO2 is present as HCO3-
- pH of natural waters = 2-12
- Precipitation: water acquires addtl substances from particulates & dust
particles suspended in atmosphere 3.8 WATER MOVEMENTS SHAPE FRESHWATER & MARINE ENVI.
-surface waters – pick up more solvents from substances through and Factors that affect velocity:
over wc they flow  shape & steepness of stream channel
-rivers and lakes have 0.01-0.02% mineral conc  reflect the substrats  width, depth & roughness of bottom
over which the waters flow  intensity of rainfall & rapidity of snowmelt
Ex. underlying rocks of limestone – composed of calcium carbonate - Fast streams: 50cm/sec flow, leaves stony bottom
- Oceans have higher conc of solutes - High water volume increases velocity
- Excess amounts of solute will precipitate & deposited as sediments - ↓ gradient, ↑ width, depth & volume of water = silt & decaying organic
- Calcium – forms calcium carbonate matter accumulate at the bottom = slower velocity
-0.014 g/L – solubility of calcium - Ripples- caused by frictional drag of wind on the surface of water
- Sodium chloride – solubility: 360 g/L (Na + Cl = 86% of sea salt) - ↑ pressure to steep side of ripple = Waves
- Chlorine – used as an index of salinity - WHITECAPS: energy supplied by wind = energy lost by breaking waves
- Practical salinity units (psu) – salinity is expressed (%) - Strong wind = higher waves
- Each particle of water remains largely in the same place & follows an
elliptical orbit w/ the passage of the wave
3.6 OXYGEN DIFFUSES FROM ATMOSPHERE TO SURFACE WATERS - As wave moves forward, it loses energy to the waves behind & disappears.
Diffusion- process wherein gases are exchanged - Swells = distant descendants of waves from far out sea
- General tendency of molecules to move from a region of high - When the bottom of the wave intercepts the ocean floor, the wavelength
concentration to lower concentration (atmosphere  surface waters) shortens and the wave steepens until it finally collapses forward or breaks
- Results in net transfer of 2 metabolically important gases (O2 & CO2) - DEEP WATERS:
- Gases diffuse slower in water  Motion does not depend on wind
- Rate is controlled by:  Movement depends on changes occurring at the surface
 solubility of O2 into water – temperature, salinity, & pressure  Seawater ↑ in density due to ↓ temp and salinity = sink
- ↓temp (cold water) = ↑solubility = ↑saturation value - Ex: warm surface currents of tropical waters move North & southward
- ↑salinity = ↓solubility = ↓atmospheric pressure = cool = ↑ density = sink (w/ high concentrations of O2) = begin return
 steepness of diffusion gradient (diff in concentration bet. Air & surface trip to tropics (deep-water currents)
waters where diffusion is occurring)  Upwelling- deep water currents meet in equatorial waters of ocean
- O2 mixed with deeper water by turbulence & internal currents  deep waters move up to the surface, closing the pattern of ocean
- Shallow, rapidly flowing water: O2 reach & maintain saturation & circulation
supersaturated levels due to ↑ of absorptive surfaces at air-water  Coastal regions: winds blowing parallel to the coast move the surface
interface waters offshore
- O2 lost by: ↑temp, ↓solubility & through uptake by aquatic life  Coastal upwelling: deep water move up and replaces surface water
- O2 decreases with depth due to ↑ demand by decomposers
- Summer: O2 greatest near the surface
- Spring & Fall: O2 replenished in deep water
- Winter: O2 more soluble; lack of diffusion under ice
- Oceanic Oxygen Profile:
 Max amt in 10-20m (photosynthetic activity & diffusion = saturation)
 ↑depth = oxygen content declines
 Open Waters: Oxygen Minimum Zone- min value of 500-1000m
- Max Solubility: 0.01L per Liter (1%) in FW at 0◦C
- Concentration of O2 in water limits respiration & metabolic activity

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3.9 TIDES DOMINATE THE MARINE COASTAL ENVIRONMENT CHAPTER 25- AQUATIC ECOSYSTEMS
- TIDES- due to gravitational pull of Sun & Moon, each causing 2 bulges - Classification based on features of the physical environment
(tides) in the waters of the oceans - water salinity- influence adaptations of organisms
- Moon Bulges: - 2 Major CATEGORIES: Freshwater and salt water (marine)
 occur at the same time: opposite sides of earth - Marine into two broad categories: COASTAL & OPEN-WATER SYSTEMS
 Earth rotates EASTWARD on its axis, tides advance WESTWARD - Freshwater ecosystem: based on Water depth and flow
 1 daily rotation of Earth = 2 lunar tidal bulges (high tides) or 2 low tides  LOTIC- flowing water (ex: rivers and streams)
at right angles  LENTIC- Nonflowing water (Ex: ponds, lakes, and inland wetlands)
 Moon side = Gravitational Attraction - FW & SW: Linked as components of the hydrological cycle
 Opposite side = due to less gravitational force than Earth’s center - GEOMORPHOLOGY: path determined by gravity & topography
- Sun Buldges: 1. Flowing water ecosystems begin as streams
 weaker gravitational pull 2. Streams coalesce into rivers
 solar tides partially masked by lunar tides 3. collect in basin and floodplains to form standing-water ecosystems such
(except when moon is full & new  E.M.S aligned = additive grav. Pull ) as ponds, lakes and inland wetlands
 Spring tides- exceptionally large high tides, w/ max rise & fall 4. Rivers flow to coast and form estuaries (transition from FW to marine)
- From “Sprungen” – brimming fullness & active movement of water - marine environment: 70% of Earth’s surface
 Neap Tides- moon is at either quarter, its pull is at right angles to the pull
of the sun (small diff. Bet. High & low tides) ; “barely enough” 25.1 LAKES HAVE MANY ORIGINS
 Mixed Tides- successive or low tides differ in height through the cycle; - Lakes & Ponds
one partially cancels out the other (Pacific & Indian Oceans)  Inland depressions containing standing water
- Intertidal zone  Mostly have outlet streams
 area lying between water lines of high & low tide  Formed through Nongeological activities
 environment of extremes Beavers- dam streams = ponds
 undergoes dramatic shifts in environmental conditions w/ daily patterns  Humans- dam rivers & streams for power, irrigation, or water storage
of inundation & exposure and construct smaller ponds and marshes for recreation, fishing and
Reasons for Inconsistent Low Tides: wildlife
 Variations in gravitational pull of moon & sun due to elliptical orbit of Quarries and surface mines- form ponds
earth - PONDS – small bodies of water so shallow that rooted plants can grow over
 Angle of the moon in relation to axis of earth much of the bottom.
 Onshore & offshore winds - LAKES – some are large that they mimic marine environments
 Depth of water  Formed by glacial erosion and deposition, craters of some extinct
 Contour of shore volcanoes, Landslides
 Wave action  Tarns- carved glacier basins filled w/ water from rain & melting snow
 Moraines – retreating valley glaciers; dammed up water behind them
3.10 TRANSITION ZONE BETWEEN FRESHWATER & SALTWATER  Also formed when, silt, driftwood, & other debris deposited in beds of
ENVIRONMENTS REPRESENT UNIQUE CONSTRAINTS slow moving streams dam up water behind them
- water from streams & rivers drain in the sea  Oxbow Lakes- dammed loops of streams that meander over flat valley
- Estuary- place where freshwater mixes w/ saltwater  Water-filled depressions – developed by shifts in Earth’s crust, uplifting
 Temperatures fluctuate considerably mountains or displacing rock strata
 Sun & inflowing tidal currents heat the water
 Upper layer may be cooler in winter & warmer in summer than bottom 25.2 LAKES HAVE WELL-DEFINED PHYSICAL CHARACTERISTICS
 Interaction of inflowing FW & tidal SW influences the salinity of the - LENTIC ECOSYSTEMS
estuarine environment  depends on light
 salinity varies vertically & horizontally, often w/in 1 tidal cycle  amt. of light penetrating the water is influenced by:
 salinity is homogenous when currents are strong enough to mix the - natural attenuation
water from top to bottom (usually at low tide) - slit and other material carried into the lake
 At high tide, SW moves upstream more rapidly = unstable salinity & - the growth of phytoplankton.
inverted density  Temperatures vary seasonally and with depth
 Tidal Overmixing- SW on the surface tends to sink as lighter FW rises, &  oxygen can be limiting
mixing takes place from the surface to the bottom - Ponds & Lakes divided based on penetration of light and photosynthetic
 Strong winds too mix SW & FW activity:
- Horizontally- least saline waters are at the river mouth & most saline at sea a. VERTICAL STRATA- influenced by depth of light penetration
- Northern Hemisphere- outward-flowing FW & inward-flowing SW are b. HORIZONTAL STRATA- obvious to the eye
deflected to the right due to earth rotation = salinity higher on left side  LITTORAL ZONE/SHALLOW-WATER ZONE:
- Oceanic fishes: move inward during pds when flow of FW from rivers is low - surrounding most lakes and ponds and engulfing some ponds completely
& salinity of estuaries ↑ - light reaches the bottom, stimulating the growth of rooted plants
- Freshwater Fishes: move into estuarine envi. During pds of flood when  LIMNETIC ZONE/ OPEN WATER:
salinity level drops (↓) - extends to the depth of light penetration
- inahbitants: microscopic phytoplankton (autotrophs) and zooplankton
(heterotrophs) & Nekton- free swimming organisms
 PROFUNDAL ZONE
- Beyond depth of effective light penetration
- beginning is marked by the compensation depth of light
- pt. where respiration balances photosynthesis
- Depends on a rain of organic material from the limnetic zone for energy
 BENTHIC ZONE/ BOTTOM REGION:
- Common to littoral & profundal zones
- primary place of decomposition

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25.3 NATURE OF LIFE VARIES IN THE DIFFERENT ZONES 25.5 FLOWING WATER ECOSYSTEMS VARY IN STRUCTURE & TYPES OF
- EMERGENTS: Cattails and sedges plants – roots are anchored in the bottom HABITATS
mud, lower stems are immersed in water, and upper stems and leaves - River emerge fully formed from glaciers
stand above water. - stream drains away from its source  flows on lay of the land and the
--- Organisms: Hydras, snails, protozoans, dragonflies, and diving insects, underlying rock formations  join new stream & other small streams,
pickerel, sunfish (lepomis spp) herons (ardeidae) & blackbirds (Agelains spp) spring seeps and surface water
- FLOATING PLANTS: Pondweed (potamogeton) & pond lily (nuphar spp.) - Below source: stream is small, straight, and swift, with waterfalls and rapids
- SUBMERGED PLANTS: species of pondweed w/ dissected leaves - Flood Times: stream drops its load of sediment on surrounding level land
- POND FISH: have compressed bodies, permitting them to move easily - Delta- formed when river deposits its load of sediment in a fan-shaped area
through the masses of aquatic plants. about its mouth  Several channels  becomes an area of small lakes,
 LITTORAL ZONE- contributes large input of organic matter to the system. swamps, and marshy islands
 LIMNETIC ZONE: zooplankton & phytoplankton (desmids, diatoms, and - Stream Classification Accdg to Order:
filamentous algae  Primary Producers), nekton (fish- distribution 1. First Order Stream- Small headwater stream with no tributaries
influenced by food supply, oxygen and temperature) 2. Higher Order- Two streams of the same order join
- Spring and fall turnovers: 3. Second Order- Two first-order streams unite
 plankton are carried downward 4. Third Order- two second order streams unite
 nutrients released by decomposition on the bottom are carried upward  order can increase only when a stream of the same order joins it
 oxygen & temperature uniform  1 to 3 (Head water streams), 4 to 6 (medium sized), > 6 (rivers)
 warm-water and cold-water species occupy all levels - Velocity of a current- molds the character and structure of a stream
- Spring: warm water & stratification develops, plankton have access to - High water increases the velocity = cuts new banks & channels
both nutrients and light - Gradient ↓ and the width, depth, and volume of water ↑ slit and decaying
- Summer- large predatory fish inhabit warmer epilimnion waters organic matter accumulate on the bottom = fast water to slow
- Winter- predatory fish retreat to deeper water; lake trout require colder - FLOWING-WATER ECOSYSTEM: turbulent rifle and the quiet pool
water temperatures  processes occurring in the rapids above influence the water of the pool
 PROFUNDAL ZONE: depends on supply of energy and nutrients from the  waters of the rapids are influenced by events in the pool upstream
limnetic zone above, & temperature and availability of oxygen - RIFFLES – sites of primary/ organic production in the stream
- Abundant w/ life during spring & fall turnovers  periphyton (diatoms, Cyanobacteria, and water moss) or aufwuch
- Easily decomposed substances partly mineralized while sinking, + organic assume dominance
debris  bottom sediments- habitat of benthic organisms - POOLS- Above and below the riffles; envi. Differs in Chemistry, intensity of
- Where Oxygen curves for lakes and ponds show a sharp drop current and depth; sites of decomposition
- Dominant organisms- anaerobic bacteria  major sites of carbon dioxide production during the summer and fall
 Amt of organic matter reaching the bottom > can be used by bottom  necessary for maintaining a constant supply of bicarbonate in solution
fauna = muck rich in hydrogen sulfide and methane
- Water becomes shallower = benthos changes 25.6 LIFE IS HIGHLY ADAPTED TO FLOWING WATER
- PERIPHYTON OR AUFWUCHS: organisms of benthic community  Streamlined formed animas- offers less resistance to fast water current
 Attached to or move on a submerged substrate but do not penetrate it  flattened bodies and broad, flat limbs- larval forms, enable them to cling
 Colonize the leaves of submerged aquatic plants, sticks, rock, and debris to the undersurfaces of stones
 Periphyton (mostly algae and diatoms) are fast growing and lightly  protective cases of sand or small pebbles - Caddisflies (trichoptera)-
attached cement them to the bottom of stones
 Aufwuchs on stones, wood & debris, form a more crustlike growth of  Sticky undersurfaces – snails and planarians cling tightly and move about
cyanobacteria, diatoms, water moss, and sponges. on stones and rubble in the current
 heavily branched, filamentous algae- Water moss (fontinalis) – cling to
25.4 CHARACTER OF A LAKE REFLECTS ITS SURROUNDING LANDSCAPE rocks by strong holdfasts
- Water that falls on land flows through the soil to enter springs, streams,  cushionlike colonies or form sheets, covered w/ slippery, gelatinous
and lakes  water transports with it slit and nutrients in solution coating – algae
- Human activities add: Nitrogen, phosphorus and organic matter  Animals of Fast water streams – require high near-saturation
- EUTROPHICATION “eutrophy” - condition of being rich in nutrients concentrations of oxygen and moving water to keep their absorbing and
 EUTROPHIC: respiratory surfaces in continuous contact with oxygenated water
- High surface to-volume ratio: surface area is large relative to depth  Slow flowing streams – streamlined forms of fish give way to fish species
- Surrounded by nutrient-rich deciduous forest and farmland such as small mouth bass, compressed bodies enable them to move
- abundance of nutrients, especially nitrogen and phosphorus = heavy through beds of aquatic vegetation
growth of algae & plants  Invertebrate inhabitants four major groups:
- ↑ photosynthesis = ↑recycling of nutrients and organic compounds = 1. SHREDDERS – caddisflies (trichoptera) and stoneflies (plecoptera); feed
further growth on bacteria & fungi of Coarse Particulate Organic Matter (CPOM)
- Phytoplankton- in warm upper layer = murky green cast 2. FILTERING/ GATHERING COLLECTORS
- Algae – inflowing organic debris and sediment, and remains of rooted - Pick up drifting downstream and settling FPOM (Fine particulate
plants drift to the bottom organic matter) – broken CPOM + feces
- Bacteria – feed on this dead organic matter - larvae of black flies (simuliidae) with filtering fans and the net spinning
 OLIGOTROPHIC: Oligotrophy – condition of being poor in nutrients caddisflies (1 & 2- detrital feeders)
- Low surface to volume ratio 3. GRAZERS
- water is clear and appears blue to blue-green - feeds on the algal coating of stones and rubble
- Nutrient content of the water is low; N abundant ; P limited - Beetle larvae, water penny (psephenus pp) and a number of mobile
- low input of nutrients from surrounding terrestrial ecosystems and other caddisfly larvae
external sources is mostly responsible for this condition 4. GOUGERS- associated w/ woody debris
- ↓availability of nutrients = ↓production of organic matter - invertebrates that burrow into waterlogged limbs and trunks of fallen
- Oxygen concentration remains high in the hypolimnion trees
- bottom sediments are largely inorganic - Predaceous insect larvae and fish such as the sculpin (cotus) and trout-
 DYSTROPHIC- “ill nourished” Feed on the detrial feeders and grazers
- receive large amounts of organic matter from surrounding land, - Mean rate of drift can serve as an index of a stream’s production rate
particularly in the form of humic material that stain the water brown
- peaty substrates or Heathlands that are usually highly acidic
- have highly productive littoral zones = dominate lake metabolism =
source of dissolved & particulate organic matter

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25.7 FLOWING-WATER ECOSYSTEM 25.9 OCEANS EXHIBIT ZONATION & STRATIFICATION
- Continuum of changing environmental conditions - Marine environment – 70% of earth’s surface
- Headwater streams – swift, cold, shaded forested regions; primary - Small volume of sunlit water & dilute solution of nutrients – limit primary
productivity is low; depend on input of detritus from terrestrial streamside production
vegetation (90% of organic input) - Seas – interconnected by currents, influenced by wave actions &
-organic matter produced enters detrital food chain characterized by salinity
- Dominant organisms: 1) Pelagic zone – whole body of water
-shredders: processing large-sized litter & feeding on CPOM •neritic province – water that overlies the continental shelf
-collectors: processors of FPOM •oceanic province
- Minimal grazers  reflecting small amount of autotrophic production -divided into layers:
- Predators: mostly small fish (sculpins, darters, trout) a) epipelagic / photic zone – sharp gradients in illumination, temp, and
- Headwater streams – are accumulators, processors, transporters of salinity
particulate organic matter of terrestrial origin b) mesopelagic zone – little light penetrates & temp gradient is more even
- Streams increase in width (order 4-6), riparian vegetation & detrital input & gradual
decrease -contains oxygen-minimum layer
- More surface water exposed to sun, water temp increases* -max conc of nutrients (nitrate & phosphate)
- Elevation gradient declines, current slows* c) bathypelagic zone – complete darkness except for bioluminescent orgs
 these changes bring abt a shift from dependence on terrestrial input of -temp is low; water pressure is great
particulate organic matter to primary production by algae & rooted d) abyssopelagic zone – “no bottom”
aquatic plants e) hadalpelagic zone – areas found in deep-sea trenches & canyons
- Gross primary production exceeds community respiration 2) Benthic zone – bottom region
- Lack of CPOM  shredders disappear
- Collectors (feeding on FPOM transported downstream) & grazers (feeding 25.10 PELAGIC COMMUNITIES VARY AMONG VERTICAL ZONES
on autotrophic production) – become dominant consumers - Lack supporting structures & framework of large dominant plant life
- Little increase In biomass of predators - Zooplankton – major herbivores
- Shift from cold-water species to warm-water species Phytoplanktons – dominant autotrophs
- Order increase from 610: riverine conditions develop - directly absorb nutrients from water
- Channel is wider & deeper - Smaller organism, greater surface-to-volume ratio
- Flow of volume increases & current becomes slower -more SA is exposed for absorption
- Sediments accumulate on bottom - Autotrophs – restricted to upper surface waters where light penetration
- Riparian & autotrophic production decrease varies
- FPOM – basic energy source used by bottom-dwelling collectors that are -algae – dominant autotrophs in shallow coastal waters
now dominant consumers -brown algae (Phaeophyceae) – most abundant assoc w rocky shoreline
- Slow, deep water & DOM (dissolved organic matter) – support minimal -includes large kelps forming dense subtidal forests in tropical rgns
phytoplankton & zooplankton population -red algae (Rhodophyceae) – most widely distributed; tropical oceans

25.8 RIVERS FLOW INTO SEA FORMING ESTUARIES - Littoral & neritic waters and regions of upwelling – richer in plankton
- Estuary – place where freshwater joins saltwater - Dinoflagellates (region of downwelling) – w 2 whiplike flagella
- Semiclosed parts of coastal oceans where seawater is diluted & partially -concentrate near surface in areas of low turbulence
mixed with freshwater coming from land -attain abundance in warmer waters
- One-way flow of freshwater streams & rivers into an estuary meets -may concentrate in summer appearing red or brown  red tide
inflowing & outflowing saltwater tides - Diatoms – phytoplantokns in regions of upwelling
- Counterflow – created when water of diff salinities are mixed; as nutrient -enclosed in silica case; in arctic waters
trap - Nanoplankton – smaller than diatom; make up largest biomass in
- Nutrients & oxygen – carried into estuary by the tides temperate & tropical waters
-vertical mixing: not swept back out to sea but circulate up & down -most abundant are tiny cyanobacteria
- 2 problems organisms inhabiting estuary face: - Haptocytes – unicellular photosynthetic algae distributed in all waters
1) maintaining their position expcept polar seas
2) adjusting to changing salinity -most impt members are coccolithophores – major source of primary
- Most organisms are benthic  attach to bottom & bury themselves in mud production in oceans
or occupy crevices & crannies
- Mobile inhabitants: crustaceans & fish  spawn off shore in high-salinity Zooplankton – converts primary production into animal tissue
water -copepods – most important; most abundant
-Size of plankton population – determined by: - Euphausiids or krill – dominant herbivores in Antarctic; feed on by baleen
-seaward movement of streamflow whales & penguins
-ebb tide transport plankton out of the sea - Carnivorous zooplankton – feeds on herbivorous zooplankton
-rate of water movement
- Salinity – dictates distribution of life in estuary Smaller organisms
- Mostly marine inhabitants able to withstand full sea water - Bacteria & protists – heterotrophic & photosynthetic; make ½ of biomass of
- Optimum salinity range – in sessile & slightly motile organisms the sea & responsible for energy flow in pelagic systems
- Anadromous fish – live most of their lives in saltwater & return to - Nanoflagellates & cyanobacteria – large photosynthesis in the sea
freshwater to spawn - Heterotrophic nanoflagellates – consume heterotrophic bacteria
-endure changes in salinity -this interaction introduces a microbial loop (feeding loop) & adds several
-estuary served as nursery & feeding ground trophic levels to plankton food chain
- Oyster bed & oyster reef – outstanding communities of estuary - Zooplankton - some species migrate vertically
- Oysters may be attached to hard objects in intertidal zone -darkness falls: rise to feed on phytoplankton
- Oyster reefs - usually lie at right angles to tidal currents, which bring -dawn: move back down
planktonic food, carry away wastes & sweep oysters clean of sediment & - Nekton – feeds on zooplankton & pass energy to higher trophic levels
debris - Photic Zone – predatory fish (tuna) are restricted
- Associated w oysters are encrusting organisms: sponges, barnacles, - Baleen whales (larger nekton) – feed on small prey, euphausiids or krill
bryozoans wc depend on oyster or algae for food - Sperm whale – attacks very large preys such as giant squid
- Rooted aquatics – provide a nursery ground for shrimp and bay scallops

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- Mesopelagic zone – bioluminescence reaches its greatest devt 25.13 PRODCUTIVITY OF OCEANS GOVERNED BY LIGHT & NUTRIENTS
-adaptations: darkly pigmented & weak body; luminescent lures; mimicry - Vertical attenuation of light in water – limits productivity to shallow waters
of prey; extensible jaws; expandable abdomens of photic zone
-luminous organs & lighted lures (in fish) – enables them to bait prey - Thermocline – limits movement of nutrients from the deeper to sthe
-search-light structures (in euphausiids and squid) – with lens * iris & surface waters where light is adequate to support photosynthesis
discharge luminous clouds to escape from predators - Rate at which nutrients are returned to surface & productivity controlled
by:
25.11 BENTHOS – plant and animals that live there 1) seasonal breakdown of thermocline & turnover
- Benthic – floor of the sea 2) upwelling of deeper nutrient-rich waters to the surface
- Darkness = heterotrophic - Coastal region – highest primary productovoty
- Polychaete worms & pericarid crustaceans– in shallow benthic regions -shallow waters allow turbulence to increase vertical mixing
- Bacteria of the sediments – important organisms in benthic food chain -coastal upwelling – bring nutrient-rich water to surface
-found where large quantities of organic matters are present - Open waters – low productivity because of permanent thermocline wc
-synthesize protein from dissolved nutrients & in turn become a source of slows the diffusion of nutrients
protein, fat, and oils for other organisms -phytoplanktons – controlled by cycling of nutrients w/in photic zones
- Vents – form when cold seawater flows down through fissures & cracks in
basaltic lava floor deep into underlying crust - Arctic – productivity is low bec of high limitations
-waters react chemically with hot basalt, giving up some minerals -light energy is lost through reflection die to low sun angle
-water heated emerges through mineralized chimneys - Waters of Antarctic - high productivity as a result of continuous upwelling
-white-smoker chimneys: rich in zinc sulphides issue a milky fluid with a of nutrient-rich water around the continent
temperature - Temperate oceans – primary productivity is related o seasonal variation in
-black-smoker – rich in copper sulphides nutrient supply driven by seasonal dynamics of thermocline
-chemosynthetic bacteria – primary producers assoc w vents; oxidize
rediced sulfur producers ECOLOGICAL ISSUES: DAMS: regulating flow of river ecosystems
-primary consumers: giant clams, mussels, polychaete worms that filter DAMS
water and graze from bacterial film on rocks - interrupt nutrient spiraling & river continuum and regulate natural flow of
water
25.12 CORAL REEFS - purpose: flood control (minimum pool), water storage (maximum pool),
- Complex ecosystems built by colonies of coral animals hydroelectric power, irrigation water, & recreation
- Rich colourful oases w/in nutrient-poor seas - Positive effects of removing dams:
- Unique accumulation of dead skeletal material built up by carbonate-  Eliminating barriers to upstream movement of fish
secreting organisms (coral, coralline, red algae etc)  Restore spawning areas
- Reef-building corals – symbiotic relationship with algal cells  Shift macroinvertebrates from lentic to lotic species upstream
-distribution is limited to depths where sufficient solar radiation is - Negative effects:
available to support photosynthesis  Short-term increases of sediment loads w/ contaminants downstream
- Precipitation of calcium –from water; to form coral skeleton  Upstream movement of invasive species
-occurs when temp & salinity are high & CO2 conc are low  Loss of any backward wetland habitat
- 3 types:
•Fringing reefs – grow seaward from rocky shores QUANTIFYIING ECOLOGY: Streamflow
•Barrier reefs – shorelines of continents & islands; separated from land by Streamflow- water discharge occurring w/in natural streambed or channel
shallow lagoons - Rate at w/c water flows through stream channel influences water temp.,
•Atolls – rings of coral reefs & islands surrounding a lagoon oxygen content, rate of nutrient spiraling, physical structure of benthic envi.
-formed when a volcanic mountain subsides beneath the surface & types of organisms inhabiting the stream
- Build up to sea level - FLOW- volume of water moving past a given pt. in the stream per unit time
- Corals – modular animals, anemone-like cylindrical polyps, with prey- Q = vA
capturing tentacles surrounding the opening/mouth Where,
-form sessile colonies Q= stream flow (m3/s)
-Gastrodermal layer: lives Zooxanthellae V= velocity (m/s)  using “current” or “flow” meter (rotating cups)
-symbiotic, photosynthetically active, endozoic dinoflagellate algae that A= cross-sectional area (depth x width)
coral depend on for most efficient growth
-Calcareous skeleton: lives Algae
-encrusting red & green coralline species & filamentous species
including turf algae
- Act as nutrient trap, so offshore coral reefs are oases of productivity w/in
relatively nutrient-poor, lower productivity seas
- Corallivores – feed on coral polyps; such as puffers & filefish