Bio 346 - Freshwater Eco. (Chpt 15) --> Use and Abuse and Restoration of Standing Waters Flashcards
What services does standing water provide? (4 things)
- Fisheries (rec and food)
- Drinking water storage and improvement
- Useful
- Recreational
What are the 5 negative effects of standing waters?
- Overfishing
- Eutrophication
- Poor reservoir design and operation
- Introduction of alien species
- Drainage and toxic pollution
What can help decrease the negative effects of standing waters?
Remedies and restoration
What is the solution of overfishing in fisheries?
Only fish the species that can stand up to fishing should be taken (be able to reproduce itself quickly)
What should be done in order to protect the stock?
Monitoring of catch and imposition of regulations on the fisheries
What happens to the yield as the fish are overfished?
Decrease
Why is yield always lower than the production rate?
- Because some fisheries are unsuitable biologically for sustained fisheries
- Hard to catch
- Cant use as food
What 3 things are required to maintain fisheries?
- The biology of the fish should be understood
- Only those species whose populations will stand up to fishing should be taken
- Should be monitoring of the catch and impositions of regulations on the fishery to protect the stocks
What 2 things increase in fish yields?
- Population
2. Economic pressure
What is hatching dependent on?
- Temp
2. Food availability
How much energy is needed to find large amount of food for large fish compared to small?
Less energy
Where do older trout like to hunt?
At the bottom of the water
Where do most species feed?
In mid waters on small species
Eg) zooplankton
What benefit do the dorsal and anal fins provide?
Provides a powerful tail thrust which allows them to have a burst of high speed
What is an example of a defence mechanism on some fish?
Some fish have spiny pectoral fins which would lodge in the throat of a predator when swallowed tail first
- This gives a grater chance to escape while the predator has to turn their prey around
- Also decreases the chance of getting stuck between rock crevices
What do young fish eat compared to older fish?
- Young fish eat only soft, submerged plants
- Older fish tackle the more emergent plants
What are 3 things that breed gin depends on?
- Environment
- Recruitment number
- Quality
What happens if breeding occurs to late?
High chance of failure to bread through early death
What happens if breeding occurs to early?
Fish may be too small and unable to cope with the energy demands
What are the 2 types of spawning?
- Spawning once and then die (putting all of their energy into reproduction)
- Spawn multiple times
What is essential to make a wise choice of species for a sustainable fishery?
Knowledge of the history of the fish
Mortality rate shouldn’t be grater than what 2 things?
- Growth rate
2. Addition of new species
Where do pelagic fish live?
In unstructured waters, with high risk of predators
What does egg guarding and low egg production and mortality mean?
Low recruitment rates
How is the production of fish measured?
Production is estimated as the increase in weight of the population per unit time and usually per unit area
What is the most widely used method of sampling fish?
By using the mark and recapture method
- Works best in smaller sample sizes
What is a length / weight graph beneficial for?
Not having to measure every fish in the future
- Can get as estimate based on the graph
What is removed below the dorsal fin in order to see the rings for measurement clearly?
Scales
What is the purpose of the scales? (3 things)
- Age the population
- Identify separately the different cohorts
- Used to estimate the growth in previous years
What are some negative aspects to the ring measurement?
Some rings may be absorbed during periods of starvation
- not 100% accurate
- Allen curve gives a graphing estimate
Where can the production in a given year be found on the graph?
The area under the curve
What happens to the darkness of the rings as the temp increases?
Rings get darker
What 2 things are associated with production?
- Nutrient loading
2. Concentration
Whats the problems with fishing?
Need to make sure it is sustained from year to year
When is rate of mortality highest and lowest in fish?
Highest = When first born and young because they are defenceless and vulnerable Lowest = As the fish get bigger and older because they can better protect themselves from predators
What does MEY stand for?
Max economy yield
What doe MSY stand for?
Max sustainable yield
What are the 5 names of the great lakes?
- Ontario
- Erie
- Huron
- Michigan
- Superior
What completely removed the freshwater habitat for much of the temperate land surface?
Glaciation
Substance fisheries depend on 1 of 5 methods
- Addition of natural plant poisons to the water
- Spears and harpoons
- Hooks and line
- Non-return basket traps
- Baskets scooped through the shallows
What were nets used to be made out from?
- First twine
- Then flax and cotton
- -> They rot easily but are cheap
What are 5 problems with mechanism farming?
- Catches are large
- Bog boats
- Large scale docking
- Cold stores on shore
- Roads and fuel needed
What do fish pellets do?
The fertilize crops for production
Farms are net users of what 2 things?
- Protein
2. Energy
What continent has the largest % of global agriculture? And what is that %?
- Asia
- 90%
What is the active fishing technique?
You use a replica fly is cast on the lured is on the surface of the water to attract fish in more lotic systems then lentic
What is course fishing?
Is when you use bait worms and dangle them in water for fish to come and bite
- More common in lentic systems
What is the difference between sport fishing and commercial fishing?
- Sport fishing uses light equipment, is meant to be relaxing and is more competitive than commercial fishing
- Commercial fishing uses big heavy boats and catches fish to sell to markets
What was one way they decreased the spread of disease/parasites?
Banned the transfer of fish with no licensed
Fish breed better in what kind of temp?
Higher temperatures
What kind of fish is huge in the global market?
Aquarium fish
Eg) Goldfish
What did industrialization lead to? (4 things)
- Increase in population
- Crowded conditions
- Poor sanitation
- Epidemics of diseases
Increases in population created a greater need for what? (2 things)
- To grow more food on rural land
- Power to drive machinery
What was the solution to industrialization needs?
Use natural lakes and artificial reservoirs to store water ready for drinking and irrigation and to generate power
Artificial eutrophication includes an increase in nutrient loading by which 2 components?
P and N
Where does the increase loading of P come from?
(3 things)
- Waste water treatment works
- Discharge of raw sewage
- Increase from arable land
Where does N come from?
Vehicles and burning
What happens to phytoplankton growth and plant growth when eutrophication increases?
They both increase
When fine particles pass through a filter and eventually clog it, what is increased in order to disinfect the water?
Chlorination
Why do shallow lakes respond strongly to nutrient loading?
Because there is less area to absorb (little shock absorbance)
What happens to growth as O2 decreases?
Decreases also
What limitations are common with the bottom of the lake?
2 things
- Nutrient limited
2. Light limited
What ways dow water enter the lakes? (2 things)
- Through direct rain
2. Inflow form catchment
Increase in nutrient loading and cultural eutrophication leads to what? And through which formation?
- Growth of algae
- Bloom formation
What do algae blooms cause? (4 things)
- Enviro and health problems
- -> they produce toxins - Anoxia which leads to killing of fish and internal nutrient loading
- Loss of habitats
- Loss of recreational usage of fresh and coastal waters
What does the input of P and N into aquatic systems lead to? (5 things)
- Eutrophication
- Fatal toxins
- Loss of aquatic diversity
- Loss of habitat
- Increase in chlorination
What are 6 land uses that affect climate change?
- Agriculture
- Farming
- Fertilization
- Waste disposal
- Harvesting
- Hydrology
What is the major way of restoring standing waters?
Is to decrease nutrient loading
- It reduced toxic algae
Who can overfishing be controlled?
- The enforcement of of proper regulations
2. The creation of reserved areas where fishing is banned to allow reproduction to take place unhindered
