FW Ecology

• well nourished
• the enrichment of waters by plant nutrients resulting in increased algal growth and related chemical and biological changes in a water body

poorly nourished

intermedite nutrition levels

were highly colored due to dissolved organic matter and poor in plankton

• forest fire in a lake catchment,
• volcanic ash fall,
• infilling by sedimentation

• land clearance,
• intensive agriculture,
• sewage outfall

• species diversity decreases
• plant and animal biomass increase
• turbidity increase
• rate of sedimentation increase
• anoxic conditions develope

• zooplankton and benthic animals and fishes
• low oxygen

Phosphoris

• macrophytes are shaded out by algal blooms.
• carp out-compete less tolerant species

caused by humans

• small test in various bottles contaning sewage or treated liquid
• Bottle bioassays are useful starting points to understand limiting nutrients but there may be serious limitations for interpretation of the results
• Bottles are closed systems with no exchange with the sediments or atmosphere or larger biota.

• Concentration alone cannot determine the limiting nutrient
• It is the rate of supply rather than the absolute amount that determines which nutrient will be limiting

• agricultural runoff,
• rain

are in principal easy to contain technologically but expensive

• Sources
• Geology
• Land use
• Population
• Processes
• Residence time
• Depth
• Stratification

• Fisheries science
• Fish species richness
• Fish classification
• Fish anatomy
• Life history
• Fish growth
• Fisheries management
• Fish productivity
• aquaculture

Species number increases with increasing surface area of ecosystem and decreases latitude

• System surface area
• Drainage size
• Larger catchment, less steep
• -More wetlands, habitat types, slower rivers
• Smaller catchment, more steep
• -Fewer wetlands, habitat types
• -Faster rivers (harder for passage)

• Latitude
• Altitude

• Lake size
• Latitude (climate, temperature, ice cover)
• Altitude (climate, accessibility)
• Dissolved organic carbon
• Total aluminum concentration

Attributed to increased habitat variability in rivers

• Time available for evolution of species
• Spatial habitat variability
• Colonization
• -Available species pool
• -Lack of geographical barriers
• Survival of immigrants
• -Feeding
• -Growth
• -Reproduction

• Laurentian Great Lakes ~ 170 species (six endemics)
• Glaciated European regions ~ 200 species

• Lake Malawi ~ 600-1000 species;
• Lake Tanganyika ~ 400 species; more disparate

• Ray fined
• (actinopterygill)

• High temperature, low latitude wetlands
• Periodically hypoxic or anoxic
• Survive out of water
• -damp habitat
• -burrowing

• Wide range of temperatures and latitudes
• Migrate to avoid low DO
• Die if DO declines below minima
• Low altitude species may gulp air
• -above surface or at well oxygenated layer

• Growth
• Mortality rates
• Number & size of eggs
• Breeding
• Brooding
• Schooling behavior

feed on fish

- feed on zooplanktion including predaceous zooplankton and fish

– feed on plant material

– feed on insects, mollusks, and crustaceans, benthic invertebrate predator

feed on anything

feed on insects

• heterotrophic protozoans,
• rotifers,
• veligers

• crustaceans,
• herbivorous zooplankton,
• benthic invertebrate nonpredator

• Gape & body size
• -Changes in food choices, types and energetics
• -Predation risk
• Vision
• -Choices in consumption
• -Risk of predation
• Swimming
• -Risk of predation
• -Migration
• Reproduction

• Environment
• -Temperature
• -Water clarity
• Consumption,Predation
• -DO
• Food availabilit
• -Population size, Competition
• -Prey availability,Timing, Abundance, Location

• Directly from recapture of marked fish by measuring
• -Increase in length
• -Change in weight which is correlated with length
• -Energy content (used less)
• Based on aging fish
• -Structures
• -Tags
• -Physical modifications
• -Length frequency distributions

• Patterns of calcium salt deposits on
• Scales
• Otoliths (inner ear bones)
• Operculum (gill cover) vertebrae
• Fin spins

• Larger catchment, less steep
• More wetlands, habitat types, slower rivers
• Smaller catchment, more steep
• Fewer wetlands, habitat types
• Faster rivers (harder for passage)

• perch,
• catfish,
• carp

are those traits of organisms that are related to their age at maturity, fecundity and age at death

• live fast die young
• Can populate quickly in areas where resources are relatively plentiful

• live slow but specialize in tough environments
• Populate slowly but can compete when resources are low

growth rate is changed to accommodate resource availability

• K=Carrying Capacity
• r=intrinsic rate of growth

(N=K/2)

• assumes a population will have a maximum in productivity at a density below the natural carrying capacity
• assumes that natural mortality can be replaced by fishing mortality without degradation of the population

scientific study of adverse affects chemicals or physical agents that may produce in living organisms under specific conditions adverse affects

20%

• Water quality- nutrient pollution N and P
• Habitat destruction bays,
• wetlands desirable for pens
• Exotic introduction of genetically altered stock
• Depletion of low value wild fish stocks for fish meal

the study of toxic substances within aquatic ecosystems.

• This includes direct toxic effects on individual aquatic organisms
• the consequences for population viability of sensitive organisms
• the indirect effects on other species which may result from exposure to toxic substances

a large dose of poison of short duration is usually lethal

a low dose of poison over a long time may be either lethal or sublethal

are identified from toxicity studies often starting in the laboratory to control other factors

coming speedily to a crisis

continuing for a long time, lingering

causing death, or sufficient to cause it, by direct action

below the level which directly causes death

brought about or increased in strength by successive additions

where death is the criterion of toxicity. The results are expressed with a number (LC50, LC70), which indicates the percentage of animals killed at a particular concentration

term used when an adverse effect other than death is being studied

the concentration at which acute toxicity ceases, usually taken as the concentration at which 50 per cent of the population of test organisms can live for an indefinite period of time.

maximum concentration of a toxic substance that has no observable effect on a species after long-term exposure over one or more generations.

concentration of a toxic waste which may be present in a receiving water without causing harm to its productivity and its uses.

Capacity to enter food chain

Resistance to degradation under environmental conditions

Ease of evaporation and atmospheric transport

toxicity remains proportional to their individual effect

if the effect is more than additive

means one toxicant reduces the impact of the other

exogenous substances that cause adverse health effects in an intact organism, or its progeny, dependent on endocrine function

Know X and Y axis

quantifiable

• Hazard Identification
• Dose-Response Assessment
• Exposure Assessment
• Integrated Risk Assessment
• Risk Management -necessary?

• Cadmium
• Lead
• Mercury

flame retardant, foam, plastic…

medication

antibiotics, antifungal

synthetic estrogens and androgens

carbon nanotubes and nanomaterial

• requires definition of the following:
• 1.Organism, function, ecosystem
• 2.What is the environment of concern
• 3.Primary endpoints e.g. mortality, fecundity etc
• 4.What is the origin of the problem

–the net accumulation of a contaminant by an aquatic organism as a result of preferential and/or selective uptake of specific substances directly from an aqueous solution to a specific location in the its body, tissues or cells

the ratio of the concentration (w.w.) in an organism to its concentration in water

–The increase in tissue concentration of contaminants or substances through a series of predator-prey relationships i.e. by means of ingestive accumulation

The net accumulation of a contaminant or substance resulting from any or all environmental sources

• strongly
• Weakly

form stable organic compounds

can bind metals and render them non-toxic

EC50 (TCDD), EC50 (compound)

TEF(concentration)

concentration in flesh sample (60mg/kg) / amount in water (5 nanograms per liter) = 12,000,000

• Related to trophic position
• Related to growth rates of prey and predators
• Study demonstrates a correlation between factors that influence growth rate characteristics in lake trout lake food webs

Biotic invaders are species that establish a new range in which they proliferate, spread and persist to the detriment of the environment

The introduction by man into the environment of substances or energy liable to cause hazards to human health, harm to living resources and ecological systems, damage to structure or amenity, or interference with legitimate uses of the environment

• The invading species has no natural predators in the new environment
• The invader is a superior competitor relative to the native fauna
• The new ecosystem has a vacant niche
• The new ecosystem is lacking species richness
• The new ecosystem is suffering from some sort of disturbance that makes it susceptible to the new invader
• A combination of the above conditions

• Reduction in biodiversity
• Destruction of habitat
• Economic losses

• Prevention
• Eradication
• Biotic Controls

This is the most cost effective measure and involves identification of potential invader species and vectors of those species, identification of vulnerable habitats and above all vigilance in enforcement of quarentines.

This method often employs chemical agents which unfortunately may have side effects as a result of not being specific to the invader. Mechanical means of eradication are costly and usually not effective once an invader is established.

This approach can be useful but requires thorough testing before application.

• Forms dense mats, especially in areas that are nutrient rich that interfere with navigation, recreation, irrigation, and power generation.
• These mats competitively exclude native submersed and floating-leaved plants.
• Low oxygen conditions develop beneath water hyacinth mats and the dense floating mats impede water flow and create good breeding conditions for mosquitoes

• Filtering removes plankton increasing light penetration
• Excretions (dissolved and particulate enrich the benthic substrate

filamentous green algae is fluorishing in parts of Lakes after introduction of mussles

• Diverse, once abundant native fish populations had collapsed:
• • Human overpopulation had increased demand for animal protein
• • Unregulated and more efficient gill netting destroyed native fishes (tragedy of the commons)
• •‘Untapped’ haplochromine biomass envisioned as food source for Nile perch

People and agriculture had been creating a more eutrophic lake

• Increased P
• Increased chlorophyll Increased invertebrates
• Nile Perch “r” traits
• Superior competitor
• Fecund
• Fast growing

• Nile perch ate them
• Decreased light compromised growth and reproduction

• Human caused exotic introductions and eutrophication
• Increased primary productivity
• Increased productivity at higher trophic levels
• Decline in biodiversity from hybridization, predation, habitat loss

• The invading species has no natural predators in the new environment
• The invader is a superior competitor relative to the native fauna
• The new ecosystem has a vacant niche
• The new ecosystem is suffering from some sort of disturbance that makes it susceptible to the new invader
• The new ecosystem is lacking species richness
• A combination of the above conditions

Increased atmospheric CO2 is resulting in the acidification of the ocean (8.178-8.068 ph ) since the industrial revolution

NOx + H₂O ↔ 2HNO₃ ↔ 2H+ + NO₃-

sulphur and nitrogen.

degree and speed

• Ratio of runoff volume to stream volume large
• Pulses especially snow melt can lower pH rapidly

Volume of lake relative to runoff volume larger, therefore lake more buffered than stream (if geology similar)

Depending on redox conditions can remove N and S and produce alkalinity

• Breaks down dissolved organic carbon
• Food supply- crayfish declined
• Habitat loss – invasion of filamentous green alga Mougeotia changed littoral nursery area
• Physiology- gill function was affected at high Al+ concentration.
• Reproduction- egg membranes were affected at low pH

reduce burning of fossil fuels

• Scrubbers and precipitators
• precipitate S in power plants and smelters

The application of limestone (calcium carbonate) provides alkalinity

powerful ozone depleters

• Warmer surface waters
• Earlier onset of stratification
• Possible change to meromictic

increase

• Climate warming
• Acid precipitation
• Ozone depletion
• Eutrophication, organic pollution
• POPs, metals, oil
• Exotics

• Fish species needing cold waters will be concentrated into smaller hypolimnions and in shallow lakes these fish may be lost altogether.
• Increased transparency in the epilimnion will allow more harmful UV light penetration and will reduce protected habitat for many shade adapted shallow water species.

slower water renewal rates will result in higher concentrations of chemicals including contaminants