Ichthyology Exam 2 (#2)

What are some of the problems with fish bioenergetics models?

Great deal of uncertainty in model inputs and testing outputs may not be possible

Wide range of differences between model performances field data and model (-84% to ~ 770%)

What are the differences between catabolism and anabolism? Between respiration and digestion?

Catabolism breaks down big complex molecules into smaller, easier to absorb molecules: releases energy

Anabolism builds molecules required for the body's functionality: require energy

Respiration provides cellular energy through ATP

digestion prepares nutrients for use

What are the major factors affecting growth? How does each factor affect growth?

Temperature: Affect metabolic rate and feeding behavior (all fish have an optimum range)

Salinity: Directly affect fish body metabolism

Photoperiod: seasonal changes change metabolism

Exercise and conditioning:

Food availability:

What are the three major classes of fish hormones?

Peptide, tyrosine derived, and steroid

What are the different ways we measure growth? (Condition factor vs SGR). What are we measuring in each one?

Condition factor: measure of energy stored "plumpness"

SGR (Specific Growth Rate): Express growth as % change in size/unit of time (weight)

What is the General Adaptation Syndrome and how does it affect fish individually? How can it affect populations?

Primary changes

Release of cortisol

Secondary changes

Elevated level of glucose in blood

Tertiary changes

Affects individuals, populations and ecosystems

Growth, survival, over fitness are reduced

Increased susceptibility to disease, lower reproduction and recruitment

What is the trophic concept? How much energy is passed from one level to the next?

Organisms are linked with inorganic materials that produce growth

Energy passed onto higher levels through an an ecosystem

Energy loss is seen as a function of food conversion from one level to the next (~10%)

How do food chains fit into food webs?

The interaction of several food chains is called a food web

Compare bottom up regulation and top down regulation in a trophic cascade.

Bottoms up regulation:

More level 1 producers would yield more level 2 consumers

In bad years, the opposite would happen

Top down regulation

Reduction in top level predators

Would yield an increase in level 3 consumers

Which, in turn, would reduce level 2 consumers

Finally, an increase in level 1 producers

What are some of the issues in using trophic cascades to describe ecosystems?

Overly simplistic

Fish do not feed at only one trophic level

Decrease of one predator may lead to increases in another

Type of predator and example: Benthic invertebrate feeders

Right - eyed flounder

Type of predator and example: Scan and pickers

Brook trout

Type of predator and example: Disturb and pickers

Plecostomus

Type of predator and example: Graspers of large prey

Moray eel

Type of predator and example: Substrate sorters

Cichlids

Type of predator and example: Piscivores

Tuna

Type of predator and example: Ambush or lie in wait predators

Northern Pike

Type of predator and example: Lure predators

Anglerfish

Type of predator and example: Stalkers

Trumpet fish

Type of predator and example: Chase predators

White Shark

How are fish diets determined? What are the pros and cons of each method?

Stomach pumping

Pros: Easy access to fish's gut contents

Cons: Impossible to do on small fish

Gut analysis:

Pros: Determining importance of food items in fish nutrition

Cons: Fish must be sacrificed and difficult to identify food items

What is Ivlev's index of Electivity? What do positive, negative, and zero values indicate?

Fish may chose one prey item over another prey item

-1: Don't want prey

0: Non selective consumption

1: Wants prey

What is optimal foraging theory?

Predicts how a fish can obtain the greatest net yield of energy.

Prey model: What are the focus, benefit, cost, and elements considered?

Prey model

Involves predators that kill and consume prey

Focus: Individual prey

Benefit: Energy input if successful

Cost: Energy and time spent in pursuit and handling

Elements considered: search time, probability of successful attack

Patch model: What are the focus, benefit, cost, and elements considered?

Patch model

Involves a predator that grazes for food without killing it

Focus: Time spent feeding in one location

Benefit: Energy input over time

Cost: Energy spent in feeding and searching for a better patch

Elements considered: Encounter rate for patches, patch residence time

What is the marginal value theorem? How does transit time affect it?

Slope indicates gain or intake per unit time

As transit time increases, time in patch increases

"Initial feeding on a school of bait is easy but gets harder"

What are the major reproductive requirements?

Events preceding reproduction (healthy, minimum age, seasonal stimuli)

Prespawning condition and behaviors (sex characteristics, migration, identify spawning area/mate)

Spawning and egg fertilization (mature and ovulating)

Parental care (may not happen)

What are the major ways in which teleosts spawn? What are the major ways in which elasmobranchs spawn?

Teleost: Most are oviparous lay eggs and fertilize externally

Elasmobranch: Internal fertilization with claspers

Oviparous (egg laying) (give example in teleost and elasmobranch)

Teleost: Giant oarfish

Elasmobranchs: All skates

Ovoviviparous (eggs that develop internally) (give example in teleost and elasmobranch)

Teleost: Common top minnow

Elasmobranchs: Tiger shark

Viviparous (live birth) (give example in teleost and elasmobranch)

Teleost: Splitfins

Elasmobranchs: Great White Shark

In viviparous elasmobranchs, compare aplacental and placental viviparity. Describe oophagy and embryology. What species would you find these types of embryonic nutrients?

Aplacental - yolk sac nutrients

Great white shark - oophagy: Developing embryos eat unfertilized eggs while still in mother uterus

Sand tiger shark (Carcharias taurus) - embryology: embryos eat other siblings

Placental - placental nutrients direct from mommy

Hammerhead sharks (Sphyrnidae)

Monogamy

One male mates with one female (Seahorses)

Polygamy

Multiple partners (Green swordtail)

Polygyny

One male mates with several partners (Slimy sculpins)

Polyandry

Females mate with multiple males (Sharks)

Promiscuity/Polygynandry

Many individuals spawning together (Green swordtail)

What is resource defense polygyny?

More than one female lays eggs in a nest/defended resource and male plays defense

What is female defense polygyny?

Females form groups for defense but males control access

What is a lek?

Places where many males gather to display to one another

Females choose "best" male

Define and compare synchronous/simultaneous hermaphroditism with successive sequential/hermaphroditism

Synchronous (or simultaneous) hermaphroditism

Both male and female parts mature at the same time

Males and females take turns releasing eggs and sperm

Successive hermaphroditism

Fish change sex at some stage

What might be the benefits of synchronous/simultaneous hermaphroditism?

Meeting of two individuals could lead to two batches of fertilized eggs

Useful for environments where fish are widely scattered or reproductive contacts are few

Define and give examples of protogynous and protandrous hermaphroditism

Protogynous: Females first and changing to male

Example: Scaridae (Parrotfish)

Protandrous: Male first and changing to female

Example: Pomacentridae (Clownfish)

What is sneaking? Describe it and give an example

Small males that follow a monogamous pair of fish to fertilize eggs

Example: Bluegill

Compare and contrast semelparity and iteroparity

Semelparity

Adults spawn and die

Iteroparity

Repeated reproduction

Young from any spawn are not guaranteed to survive to adulthood

Oceandromy

Searun migrations between feeding/wintering and spawning grounds

Example: Atlantic Bluefina Tuna

Diadromy anadromous

Adult fish migrate from ocean to spawn in freshwater

Example: Salmon

Diadromy catadromous

Adult fish migrate from freshwater to spawn at sea

Example: North American Eel

Diadromy amphidromous

Larvae hatch in freshwater, drift to saltwater briefly, then return to freshwater to grow and reproduce

Example: Gobies

Potmodromy

River-run migrations up rivers or between lakes and river

Example: Cyprinids

What are the five stages of development (ontogeny) in fish? What are the major occurrences in each (when does one start and the other begin?)

Embryonic period

Begins with fertilization

Larval period

Begins when fish has ability to capture prey

Juvenile period

Begins once fins are fully differentiated

Adult period

Development of reproductive tissues and structures

Senescent period

Reduced gamete production

Prey capture methods

Herbivore: Parrotfish eating plant matter

Carnivore: Pike eating fish

Piscivores: Barracuda eating fish

Zooplanktonvores: Sardines eating zoos

Benthivores: flounder eating benthos

Detritivores: Plecostomus eating organic debris

Fish diets

Epifauna: scrape from rocks

Euryphagous: mixed diet (unstable environment)

Stenophagous: limited diet (stable environment)

Monophagous: one food type (carnivores)

Dead end filter feeding

Food particles are caught on the rakers and can only eat a small range of particles

ex. Basking Shark

Cross Flow filter feeding

Water flows across a porous structure then water is squeezed out and particles are concentrated & swallowed. Allows for a wide range of particles

ex. Whale Shark

Relationship between gut length and diet composition

Gut length is dependent on fish diet where herbivores have longer tracts than carnivores.

Describe digestions and major organs & compounds

Food is broken down by enzymes and acidic secretions. Starts in stomach with protease at an optimal pH of 2-4. Stomach distention stimulates HCl secretions. Additional protein digestion occurs in the intestines

Trypsin from Pancreas Bile Salts from Liver

How are products of digestion absorbed

1.) Diffusion: active or simple both do not require energy

2.) Active Transport but needs a carrier and energy to move compounds

How are nitrogenous wastes eliminated?

Protein breakdown creates nitrogenous waste, and compounds are directly excreted into water.

How does ammonia toxicity work?

Increases internal pH thus inhibiting key enzymes needed for energy generation.

NH4 substitutes for K+ ions = disruptor

Nitrogen Cycle

1.) Nitrosomas convert ammonia to nitrite

2.) Nitrobacter convert nitrite to nitrate

3.) Plants take up nitrate