Bio 346 - Freshwater Eco. (Chpt 26) --> Fish and Water Birds Flashcards
What do aquatic birds exert and important effect on?
The abundance and community structure of macro-invertebrates and fish
What are the greater size I’m most fishes associated with?
- Greater longevity (life expectancy)
- Slower biomass doubling time
- Much higher mobility
How many inland fish species are there? And what are the 2 groups they can divide in?
- 11,000
- Can be divided into groups with jaws or without jaws
Where do the air-breathing lung fishes live?
3 things
- High temp
- Low latitude wetlands
- Likely to become hypoxic or anoxic
What do the teleost fish behaviourally respond to?
Low dissolved O2 [ ] by migration of local movements
- Die if DO is below species-specific minima
Different parts of the world have different fish because of what 3 things?
- Environment
- Competition
- Predators
What are the number of species affected by? (4 things)
- Latitude
- Altitude
- Dissolved organic carbon (DOC)
- Total Al [ ]
What does life history refer to? (6 things)
- Where a species lives
- How it feeds
- Food preferences
- Growth
- Mortality rates
- Behaviour
What percent is the mortality from eggs to larvae?
Greater than 99%
Cohort
Number of fish of a given age
Year-Class strength
Number of fish spawn during single season
Why do young fish commonly change habitats?
3 things
To reduce the risk of…
- Predation
- Cannibalisms
- Competition for food or habitat
Where do fish like to live?
Tend to live in selective vegetated inshore areas that provide better protection for predation compared to open waters
What effect of age-0 fish have? (2 things)
- Abundance of zooplankton prey
2. Alters species composition and size distribution
Why are some cohorts strong and some weak?
Temporal or spatial match between larvae and abundance of prey or predators during “crucial period”
Crucial period
When larvae have absorbed most of egg sac and are feeding independently
Food limited
Density- dependent growth
Food not limited
Density independent growth
Low water
Growth arrested
High water (flood)
Growth, reproduction
Poor flood
Poor growth, no reproduction (stunted)
When is survival the highest?
When food is abundant and predation is low
- Competition must also be considered
What cab high survival rate lead to?
Stunting
Stunting
To stop, slow down, or hinder the growth or development of species
- Poor population growth
What are 5 determinants of fish growth?
- High latitude
- Strong seasonality in temp
- Irradiance
- Resource ability reflect in seasonality variable growth
- Flood season
What are seasonality in growth at low latitudes often linked to? (3 things)
- Seasonal floods
- Drought affecting habitat
- Resource availability
What are 2 ways to measure growth?
- Mark and recapture
2. Inner ear bone rings (otoliths)
Larger fish grow at what kind of rate?
Slower rate
Production (P) from biomass (B) does what with size?
Decrease
What does P:B ratio define?
Biomass growth rate
What can differences in ratios indicate? (3 things)
Differences in…
- Productivity
- Genetics
- Species-species/species/enviro interactions
What happens to biomass and density as fish size increases?
Decreases
How can you determine structure of population?
Multiplying P:B ratio of each cohort by biomass density
What age of fish has a higher specific feeding and respiration rates?
Younger fish
What re young fish a major source of?
Regenerated nutrients through nutrient excretion
Fish exert what kind of effect?
Top-down (predation) and bottom-up (nutrient supply)
What are 5 ways you can estimate population in inland waters?
- Traps
- Gill nets
- Seines
- Trawls
- Poison all the fish
What does electroshocking do?
Temporarily immobilizes the fish so they can be scooped up for estimation
What is echolocating?
An acoustic method that involves sending 1 or more beams of ultrasonic sound waves either downbeat at specific angles from the boat
- Waves from fish are bounced off and detected by the screen
What is a + and - thing about echolocating?
\+ = Easy to track - = Cant tell the specific species
What kind of sample size works best for the mark and recapture method?
Small sample size
Mark and recapture assume 3 things?
- 100% random mixing (all have the same probability of getting picked)
- Same mortality (the tags don’t increase or decrease of survival)
- No immigration on emigration
What do they use scientific surveys for?
Measure population size to determine how much of a population can be fished
Whats one way to look at abundance of fish?
Catch per unit effort (CPUE)
What does CPUE stand for?
Catch per unit effort
Traditional model
View each population has separate entity that can be modelled independent of competitors, predators, resources and environment
What is the traditional model useful?
When fish stocks are large, stable and not overfished
Growth over fishing
Modest overfishing can permit rapid recovery when fishing pressure is reduced
Negative effect of traditional models
They lack predictive power when overfishing of larger and most producing of individuals cause major change in population structure
Biological Overfishing
this type of overfishing causes significant chains to energy flow efficiency and food web structure
- Major problem in inland waters
What are 6 things fisheries management includes?
- Setting size and quality (bag) limits for individuals in recreational fisheries
- Restrictions on fishing gears
- Restrictions on capture and retention of particular species during certain critical periods
Eg) Breeding season - Setting fishing quotas in commercial fisheries
- Limiting number of commercial fishing boats
- Selectivity stocking hatchery reared fish
Community fish biomass increases with ___ and decreases with ____
- Increases with trophic status
- Decreases with nutrient supply declines
What happens to TP as total biomass decreases?
Decreases
Production
Elaboration of new tissue biomass over a time interval
Allen curve
Is a way of estimating the production and yield
- Plot a mean number of fish against mean body size and measure area under the curve
What are 3 things that production is strongly correlated with?
- Population biomass
- Weight of largest size-class of fish in population
- Temperature
As fish production increase, what happens to biomass?
Increases
Temperature has what kind of effect on protection and why? (+ or -)
Positive and at lower latitudes cause it is more favourable and the growing seasons are longer
Substantial fish production will be higher for what size of species?
Smaller
What does MEI stand for?
Morphoedaphic index of yield
What does MEI use?
Uses ratio of total dissolved solids (TDS) to mean depth (Z) as a surrogate for population yield of species
What is mean depth a good predictor for?
Fish yield
What is MEI used for? (3 things)
Quick approximation of the yield of…
- Lakes
- Reservoirs
- River wetland systems
What are 8 things mean depth effect?
- Distribution of organisms
- Lake stratification
- Light climate
- Relative size of littoral zone
- Water temp
- Flashing rate
- Nutrient supply
- Catchment
What does a modest increase in resource availability allow?
Higher fish production without changing composition
- Not the case when nutrients produce hypoxia or anoxic hypolimnia or when phytoplankton abundance is sufficient to cause disappearance of submerged macrophytes
What can an increase in eutrophication do?
Shift fish community to be comprised of greater zooplanktivorous fish biomass, lower % of piscivorous fish
High transparency is incompatible with what?
High fish production
Who much of the inland yield is for agriculture?
50-70%
What species dominate worldwide?
Carp species
Aquaculture
Farming of aquatic organisms
What are the 4 types of aquaculture?
- Extensive
- Relatively natural conditions - Semi-intensive
- More controlled conditions, diet supplement, high stocking densities - Intensive
- More intensive management and additional feeding (often monocultures) - Hyperintensive
- High value species at high densities in cage
- All aspects are controlled
What culture is aquaculture waste production best studied?
Hyperintensive culture
When are outputs the greatest? And what are the outputs?
- Greatest in the spring and summer when feeding and temp are the highest
- Outputs are organic matter and nutrients
7 ways fish farming affects limnology through:
- Water quality
- Destruction of good habitat
- Removal of young fish for culture
- Introduction of exotic species
- Genetic effects
- Disease and parasite introduction
- Raising piscivorous fish require large input of wild fish for feed
What is affected by water birds richness, biomass and composition?
- System morphology
- Littoral vegetation
- Trophic status
What happens to species richness with increase in system size?
Increases
Where is birds density productivity most highest?
In the littoral zone
What is the riparian zone (land-water interface) important for? (4 things)
- Feeding
- Resting
- Breeding
- Hiding
Systems with long shorelines relative to open water have what?
High abundance and biomass of birds
What kind of relationship is between tropic status, bird numbers and biomass (+ or -)
Positive
What is large scatter in data caused by? (6 things)
- Human disturbance
- Nearby size of wetlands
- Underwater slope
- Anoxic area
- Variation in dominant predators
- Competition
