Osmoregulation Immunity Stress and Disease Osmoregulation Immunity Stress and Disease

HK Adrenalin

Head Kidney Cardinal Vein Chromaffin Cells Brain Nerve

The Beneficial effects of epinephrine/adrenaline are…

Better “fight or flight” capabilities

Increases heart rateIncreases heart rate Increases breathing (respiration) rateIncreases breathing (respiration) rate Opens gill circulatory systemOpens gill circulatory system Open muscle circulationOpen muscle circulation Decreases blood to gutsDecreases blood to guts Releases sugar from liverReleases sugar from liver

There is no such thing as a free lunch !

Gill Anatomy Lamella Afferent Artery Efferent Artery Afferent Artery Cartilage Rod Efferent Artery Water Flow

FreshwaterFish Water Salt

SaltwaterBony Fish Water Salt

SaltwaterShark Water Salt =Trimethylamine oxide (TMO) and Urea

Epinephrine makes all osmoregulatory problems FW fish gain more water and loose more salt Saltwater fish gain more salt and loose more water Sharks gain more salt Hagfish.. well…they stay hagfish! worse

Starvation Entrapment Injury Social problems

Brain HK Interrenal Cells ACTH Adrenocorticotropic Hormone Cortisol

Good Effects of Cortisol ? Protein catabolism –Breaks down protein for energy

There is no such thing as a free lunch !

Complement molecules begin to assemble a complex on the wall of a bacterium Complement finishes forming a channel through the bacterial cell wall.

Lysozyme Dissolves bacterial cell walls Found in –Blood –Mucus –(tears)

Antibodies bind all over a Rhabdovirus and block it from infecting a cell.

Antibodies recognize foreign antigens on an “ich” parasite and mark it for destruction.

Uh-Oh! Some proteins are really important ! –Antibodies: kill things, flag things for destruction –Lysozyme: dissolves bacterial cell walls –Complement: pokes holes in bacteria, flags things for destruction Macrophages: need those flags Neutrophils: need those flags Eosinophils: need those flags

Cortisol Downsides Cortisol triggers catabolism of immune system proteins Cortisol saves scarce resources by reducing expenditures on immunity –Less white blood cells –Less production of immune proteins

Epinephrine: Makes osmoregulatory problems worse Cortisol: Screws up the immune system

The Case Bluegills harvested in July 75-95% die from columnaris infections

The Problem When fish are loaded onto the trucks and into raceways, they perceive it as life- threatening They make cortisol and epinephrine Osmoregulation problems Immunity problems

The Cure No treatment –95% die Gentle harvest –90 % die Add salt –85% die Add penicillin –5% die

The Case Threadfin shad are harvested and loaded on trucks 100 % die within 1 hr

The Problem When threadfin shad are loaded onto the trucks, they perceive it as life- threatening They make epinephrine Osmoregulation problems

The Cure No treatment –100 % die Gentle harvest –100 % die Add salt –95 % die Add antibiotic –95% die

The Case Catfish develop ulcers and die 3-7 days after delivery Cultures show common soil bacteria

The Problem Stress triggered cortisol production Cortisol screwed up the immune system The fish became susceptible to bacterial infection

What was the stress? Normal fish: 1,000,000 bacteria required to cause infection Oxygen depleted fish: only 100 The neat part: It turns out that the fish truck had an oxygen accident! Bacteria levels were probably high in the pond

The Cure

The Case Catfish look normal in aquariums Turn rigid if handled Much worse if fish aren’t feeding

The Problem Stress triggered epinephrine release The fish had osmoregulatory problems

Why is it a problem here? Very low mineral levels in the water Minerals from the feed are needed

The Cure

The same thing happens with grass carp: They are tough in hard water but Fragile in soft water

Many common procedures used in aquaculture and fisheries are perceived by fish as life threatening, but really aren’t Hauling in trucks Seining Weighing Holding in tanks Aerator noise…

If the fish make a bunch of epinephrine or cortisol, they suffer the ill effects, but get no benefit. The answer is to 1.reduce their perception of danger, calm them with tranquilizers (if appropriate) 2.deal with the side effects using salt manipulation and antibiotics if appropriate

If conditions really are life threatening… Rapid temperature changes Poor water quality Handling injuries Disease

Then, the hormones and their effects are vital to fish survival… But, you must 1.help the fish deal with the negative side effects 2.try to reduce improve the dangerous situation

Cures Epinephrine –Gentle handling –Salt adjustment for osmoregulation –Tranquilizers 1 for open water fish Cortisol –Gentle handling and holding –Antibiotics 1 for immune problems 1. Use only if required, safe, and LEGAL

Problem - Solution EpinephrineEpinephrine –great for fight and flight –screws up osmoregulation CortisolCortisol –great to provide energy in long lasting emergencies –screws up the immune system EpinephrineEpinephrine –Gentle handling –Salt adjustment for osmoregulation –Tranquilizers for open water fish CortisolCortisol –Gentle handling –Antibiotics for immune problems