BIOL 316 WEEK 4 NOTES

Lecture 1:

Information sources for seafoodo Seafood watch, seachoice.org, marine stewardship Council (MSC) – World

certified for seafood products, oceanwise Resources on what consumers should buy based on the sustainability of fish populations

Feeding:

Type of food at certain life stages are consumed across different species of fish Pressure increase in smaller fish species to feed farms Change in local species and genetic diversity in lakes Many types of feeding strategies exist across species

Energy Budget:

Discussed earlier in the course C=Pg+Pr+R+U+F

o Used to identify total energy consumed and how it is used in the animal

Feeding strategies – Know these categories

Detritivores – Dead material Herbivores – Plant material Omnivores- Animals and plants Carnivores – Living animals

o Sub classes: Microcarnivores: Zooplankton or larval fish Microcarnivores: Larger animals

Anatomy of mouth and digestive tract= specified to the type of feeding strategy used

Piscivorous Fish:

Many different feeding strategies exist Biggest fish in communities (These are usually Tuna and Bass) Potential has a greater impact on communities through predation First few months of life, shift to Piscivory

o Growth/ development is faster for these types of fish Secondary Piscivores -> shifts later in life style Zooplanktivorous -> Piscivory (Life history trait)

o Some species (Tuna) skip zooplanktivorous stage Pays to get big fast Spawning early -> Pikes and largemouth bass

o Beginning in spring (most spawn in summer)o Are bigger by the time summer comes by, increase predation of summer

spawners

Trophic Cascade in Fresh Water

AbundancePiscivorous Increase Decrease

Zooplanktivorous Decrease IncreaseZooplankton Increase Decrease

Phytoplankton Decrease IncreaseConservation management:

Removal of top predator in fishers = important impacts

Foraging: Theoretical approach (General Principles)

4 components of predation prediction choiceo Number Prey in environmento Number of prey encounteredo Number of prey attacked o Number of prey consumed

Trade off between size for prey size: predator size Extreme = eating anything available

Optimal Foraging Theory:

Predator prefer prey that yields greater energy per unit of handling time Increase in higher value prey population results in a decrease in low value prey captured

Ideal free distribution theory:

Fish select environment that maximizes fitness Mortality (µ) and growth rate (g) ratio -> habitat that minimize their ratio

Three models:

Lecture 2:

Trophic Ecologyo Fish feeding cycles change if new species are introduced

Example: Invasive species o Species in or out will change the trophic level

How different species interact with ecology will influence trophic levels as well Ecosystem management approaches should replace single-species approach

Ecosystem Management:

Capture success

Prey/ Predator size Prey/ Predator size

Handling Size

Prey/ Predator size

Profitability (net energy gain)

Optimal

Tools used in this field have increased due to advancements in technology Trophodynamics: Study of flux in nutrients and energy in experiments

Food Chain:

Transfer efficiency ~10% is transferred per stage/ step in the trophic level Quantity comparison between ecosystem

o Cannot include all trophic levels involvedo Implies that bottom level = Implies unused material lost to ecosystem

Food web:

Greater complexity compared to food chain Includes different life stages and feeding levels Within entire community, dietary analyses (greater connection)

Analysis of stomach content = ID of contents is hard

Due to digestive system/ processes breaking down what is eaten

Only allows for a “snapshot” in time Limited gut content (digestive stages = breakdown) Only allows analysis of a few hours to a few days

Molecular (DNA) approaches for Stomach content:

Visual taxonomy = ~10-20% DNA barcoding = ~80-100%

Stable isotopes:

Like a fingerprint of food webs Use of 12/13C or 14/15N

o Concentration increased with feeding – enriched/ heavier isotopes Degeneration of isotopes only occur through respiration, catabolism, excretion. Etc Tells us relative position in food web Helps determine migration patterns, ontogenetic shifts in diet and ID long term change in

feeding patterns

Fatty ACID Profiles:

“Middle time ID” Fatty acids slowly breakdown in the body of consumed organism Lipid stored as fatty acids, many different types of fatty acids can be ID

Summary of methods:

Stomach content: ID from hours to a few days

Fatty acids: Weeks to months

Isotopes: Months to years

Lecture 3:

Migration: movement of individuals and population from one geographical area to another

Cyclical element, this is what distinguishes it from dispersal Track spawning patterns In/off-shore, few km in traveling distance and exists in many fish species

o Can be 100’s of km such as cod, herringo Can be 1000’s of km such as tuna, billfish, salmon

Oceanodromous – Sea/ Salt water Potadromous – Fresh water Diadromous – Sea and fresh water migrators Anadromous - Like Salmon

o Feeding and growing is in the ocean/ salt watero Reproduction in freshwater, very little feeding occurs in this stage

Catadromous – Like Eelo Feed and growing is in freshwatero Reproduction in ocean/ saltwater, very little feeding occurs in this stage

Increases reproductive and survival success Environmental changes, better for specific goals Resources change, not limited to one specific habitat

Bluefin Tuna:

Atlantic tuna Come from two specific places

o Eastern side = Mediterranean o Western side = Gulf of Mexico and Florida

Salmon:

Water is clear and species is larger in size Sea = feeding and growing Fresh = reproduction Atlantic sea = declining salmon population Greenland – greatest feeding area because it was an old commercial fishing area for

salmon

Eels:

Building of dams = decrease in migratory path = decrease in eel population Ocean = lay eggs Quebec = commercial fisher for Eel