Exotics 2 Flashcards
In terms of population level effects from disease what are the main ones and what lead to and what are the 2 main individual level
Population 1) reproductive rate 2) mortality 3) behaviour/migration -> effect population size -> ecosystem flow on effects (top-down to bottom-up) Individual 1) mortality 2) sub-lethal effects at host level
Ecosystem flow-on effects (Tropic cascades) what are the topic levels in the ecosystem
BOTTOM - producers - plants - primary consumers - herbivores - secondary consumers - carnivores that feed on herbivores - tertiary consumers TOP
Give examples of disease that cause trophic cascades top-down control and bottom-up control
Top-down control: Devil facial tumour disease and effects on small marsupials (increase feral cats as competition with Tassie devils result in decrease in quolls)
- Problems start at the top with carnivores
Bottom-up control: Rabbit haemorrhagic disease and effects on Iberian lynx (iberian lynx dependent on rabbit numbers, crash correlated)
- Problem start at the bottom with producers or herbivores
Chlamydia in koalas what does the lack of disease mean for individual and population levels
- Lack of disease, can lead to overabundance, especially if other controlling factors are missing
○ Present -> body condition worse and reproductive less
○ French Island (Chlamydia free) -> overabundance of koalas - RESULT -> increase in primary consumers (koalas) but also decrease in other animals as decreasing the producers (their feed)
○ Will eventually lead to a crash
What are 7 main factors the predispose rare species to extinction due to disease
- Multiple disease outbreaks in clumped distribution, or very small population in one area
- Slow but lethal -> facial tumour
- Reservoir hosts
- Changes in susceptibility or new pathogen
- Host behaviour
- Other threats already present, stochastic events
○ Fragmentation -> increase inbreeding and therefore population susceptibility as well as possibly resulting in an immunologically naïve population that then when exposed leads to high levels of infection - Disease may also have significant impacts on ex-situ conservation efforts - captive breeding
White Nose Syndrome (Pseudogymnoascus destructans) what is the pathogen, the effect on the bat, location, population and individual level
- Fungus introduced into Norther American -> invades body systems, wings, fur but not the lesions that cause the issue
○ During hibernation in winter -> kept waking up during winter, cannot find food -> maceration -> starvation
§ If survive through winter can then control when warmer weather (fungus prefers colder temperature) - Endemic in Europe but mortality is not found as high there -> possible co-evolution
- Bats -> primary consumers, important for control of insects which is important for agriculture
- HIGH mortality - 90-100% cave dwelling bats
White Nose Syndrome (Pseudogymnoascus destructans) what are the 4 main disease influencing factors and main effect
a. naïve population
b. Population density
c. Hibernation/resource availability is low in winter
d. Temperature - low in winter when cause most issue
CONSERVATION THREAT
Chytrid disease - Batrachochytrium dendrobatidis what species important for, what occurs, what are important factors with individual, population, environment effects
- Southern gastric-brooding frog - NOW EXTINCT due to this
- Extinction of 250 frog species world wide
- Tadpoles become infected, once becomes frogs covers the skin and then they die
- Multiple strains -> highly virulent strains causing the extinction events
○ Thought to come from east asia - Ways for recovery
○ Individual -> innate immune response, adaption to faster maturation, innate or adaptive behavioural fever
○ Population -> disease impact variable across life-stages,
§ BAD -< if reservoir hosts
○ Environment -> environmental refugia - more access to sun when bask, heat tends to kill fungal spores
§ BAD -> environmental optimal conditions for growth of the fungus
Chytrid disease - Batrachochytrium dendrobatidis treatment and main effect
- Treatment
○ Individual -> itraconazole (antifungals for individuals)
○ Population -> biosecurity, increased salinity, lots of invertebrates within the water (ciliates - gobble up fungus)
CONSERVATION THREAT
Toxoplasmosis what is the definitive host, intermediate host and effects
- Cats definitive host
- Intermediate host -> eating animal with cyst OR eating something contaminated with cat faeces
- Can affect ANY warm-blooded but marsupials more susceptible possibly due to not co-evolving with felis
- Accumulate in marine environments in filter feeders - molluscs can affect otters
CONSERVATION THREAT
Tasmanian devil facial tumour when does it first appear, effects and epidemiology
- First appeared in 2005 in Tasmania -> contagious cancer from single female cell
○ Antigens aren’t presented on MCH class I and II - invades immune system - 6+months to live once infected then die
○ Inability to feed due to cancers around the mouth as well as metastasis - SECOND facial tumour now found -> unsure on relationship seems to be different
Tasmanian devil facial tumour what is the main effect and epidemiology
CONSERVATION THREAT
- Epidemiology
○ Affects generally more dominant and healthy animals as generally more aggressive so bite (transmission)
○ Decline in 80-90% in Tasmanian devils
§ Not total crash in the populations -> possible selective pressure resulting in evolution of the population to become more resistant
○ Frequency dependent disease
Sarcoptic mange what species important with, what leads to, prevention and the main concern
- Wombats -> smaller populations can become extinct through this -> can be a conservation threat
- Severe hyperkeratosis as other species but also HIGH levels of numbers - systemic disease, organ failure, maceration
- Earlier stages of disease feasible to treat
- Prevention? -> challenging at the moment only option is flaps on the burrows but need high labour and isolated populations for high effectiveness
○ Need to eliminate every mite -> cannot know how effective the treatment is without skin scraping
ANIMAL WELFARE
Beak-and feather disease (psittacine circovirus) what species found in, how spread, main effects
- Acute death in young birds, older become chronic infections - die or become carriers
- Lots of species of carriers -> rainbow lorikeets
- Generally doesn’t lead to conservation issue UNLESS other pressures on that population
○ Orange belly parrots -> very low numbers less in the wild so loss of a few individuals is significant
Human and livestock health what are the 3 main effects need to consider and describe a disease that effects this one health approach
1) animal health 2) human health 3) ecosystem health
Nipah virus
- South east asia -> people infected straight from pigs - pigs infected from flying foxes that drop half eaten fruit within the piggeries
- Why occur -> move into closer contact with pigs because
○ Habit loss, environmental diseases result in migration towards these areas
What are 3 important ecosystem effects that affect rate of emerging disease
- Changes in biodiversity -> Species richness
○ Dilution effect -> range of host pathogens can choose from but only a few are the best carriers - others will eliminate
○ Amplification effects -> more different hosts and all are good at transmitting disease - INCREASE?
○ Which is it? -> depends on the situation - Increased human/livestock/wildlife interfaces -> greater likelihood of pathogens moving into different hosts
- Indirect effects on disease susceptibility
Give an example of a disease where dilution effect from changes in biodiversity affects rates of emergence
lyme disease carried by a tick -> birds, possums, mice are hosts
□ Mice is the best at carrying the virus -> if have multiple species/hosts then tick go onto that and be eliminated
□ In fragmentated environments increase mice and decrease other species -> increase survival of tick and prevalence
What are 4 main differences in an aquatic environment
- Oxygen availability
- Exposure to waste products and nitrogen cycle
- Temperature and effect on animals
- Exposure to salinity and pH
What are important structures in aquatic animals
- Gills and buccal/opercula pump
- Skin -> living cells, can heal rapidly, IMPORTANT BARRIER TO OUTSIDE WORLD
○ Salt water -> immediately water pulled out will rapidly dehydrate and VICE VERSA in fresh water
§ Will need to work overtime to maintain internal osmotic environment - Swim bladder
- Lateral line -> vibrations in water
- GIT -> very different between species
- Immune system and haemopoietic tissue -> no bone marrow
What is important about poikilotherms and how do tuna and salmon deal with it, what temperature is stressed and why - what to do in this situation
- Metabolism related to water temperature
○ Cannot regulate temp due to Gills -> large surface area for heat exchange straight in contact with water - Tuna -> red muscle on the inside of white muscle (insulated) able to regulate their temperature
- Salmon -> get stressed when temperature above 19 degrees
○ Increase Temperature -> oxygen concentration decrease AND will require more oxygen due to increased stress - DON’T FEED AND DON’T STRESS THEM
Gills function, how achieve what are the 2 main parts of the gill and their structure and function
- Extract oxygen from within the water -> lower concentration generally than air
- Tiny blood vessels -> blood comes into contact with water via membranes and oxygen comes across to haemorrhage
- Gill arch -> has primary filament comes down with secondary lamellae (channel where blood flows through and where capillaries are located) - GAS EXCHANGE SURFACE -> once comes out of water these channels collapse (cannot breathe)
○ Blood flows opposite to the flow of water to optimise gas exchange
○ TUNA -> fusion between primary filaments and tops of secondary lamella - Gill rakers -> protect the gill (act as a sieve water moves through)
- Sit under operculum cover
What are the 3 main types of ventilation with fish gills and the type of fish present within
1) Ram ventilation -> must keep their mouth open and kept moving to get water flowing over gills
○ EG - tuna
§ WHY DOESN’T IT HAVE BOTH -> buccal pump mechanism takes a lot of energy (why tuna doesn’t have) ALSO need space for this muscle so tuna just have bigger gills
2) Pump mechanism -> can sit still and pump water through gills
○ EG - goldfish
3) Combination of both depending on whether moving or not
○ EG - salmon
What leads to disease within a tank/ closed ecosystem
Ecosystem - has a bearing capacity -> temperature, salinitiy, plants, animals, micro-organisms
Added pressure - farming activities, unrelated water activies, land based activities, climate change can change the capacity
RUPTURE
- changes in biotic and abiotic parameters - induced changes in these parameters -> STRESS -> DISEASE
What are 7 common causes of added stresses on aquatic animals
- Temperature -> optimal temperature and quick changes
- Dissolved oxygen -> FIRST THING TO LOOK AT - emergency
- Salinity -> salmon and barramundi need both marine and fresh water
○ Change in salinity can be used to treat amoebic gill disease in Atlantic salmon - Ammonia -> NH3 can become toxic at certain levels (ionised)
- pH -> amount of ionised (toxic) and non-ionised ammonia varies with this
- CO2 -> can affect pH
- Currents
What are 7 additional causes of added stresses on aquatic animals
- Predators - fish not feeding, poor feed conversions
- Suspended solids - river system with flood - dirt wash into the system
- Pollutants/toxins
- Overcrowding
- Handling
- Nutrition
- Treatments - formaldehyde, copper
What are 8 main steps in the examination of a fish health problem on a fish farm and what looking for within
- History
○ Mortality -> rate, is it increasing in rate, are all tanks involved
○ Duration, system, fish (how many, rate), species (if two species on farm are both being affected), clinical signs, water quality
○ Feeding (changes?), handling/grading, any treatments (vaccination) - Site visit
- Examination of a fish as a group
- Examination of individual fish
○ Eating, schooling (fish), colour, alert, gill movements, mortalities, circling, spiralling, flashing
○ Growth rate, food conversion rate, feed storage, smolt quality - Sampling of fish
- Sampling of water
- Laboratory
- Advice +/- treatment
Abalone disease outbreak what species within, mortality, disease agent and transmission
- Abalone are snails -> shallow troughs live within
- Mortality -> 5-90%, significant cumulative mortality, one year old stock appeared worst affected
○ One year old stock appeared worst affected
○ Another pump ashore farm affected - destroyed stock immediately after seeing high mortality
§ No further signs until months later
○ Two other sea based farms affected - Disease agent found to be a herpes like virus
○ Transmissible through water
○ Highly virulent
○ Diagnostic lesions - ganglioneuritis
○ Abalone viral ganglioneuritis - Wild abalone affected in the vicinity of one farm - now spread through wild (or is it simply that we are now LOOKING)
What is important with aquarium environment and what is needed to help with that
The aquarium environment
- Closed environment has consequences -> accumulations of waste, organics, nutrients
- Water is a culture medium - add fish or add nutrient = microbial growth
The aquarium environment
- Aquarium filtration
○ Mechanical -> will get clogged -> need to clean
○ Biological - converts
○ Chemical - absorbs -> certain amount can absorb after this need to change
- Aquarium filter is an expanded aerobic environment for colonisation by Nitrifying bacteria
Describe the ammonia cycle and which ones are toxic and what occurs during detoxification process
Ammonia is broken down by nitrosomonas to Nitrite
Nitrite is broken down into nitrate into nitrobacter
Ammonia and nitrite are toxic
Nitrate isn’t toxic but acts as food for bacteria -> over population so still need to remove
H+ accumulates during detoxification -> pH drops as filter starts to work
Biological filtration what occurs, what can add to it, how to test
- Conditioning period for enough nitrifying bacteria to develop varier (2-6 weeks)
- Can be shortened by inoculating with live gravel -> will already have the bacteria present
- Test kits for ammonia, nitrite, nitrate are available
- Acid shift occurs due to H+ production
- Filters must be kept healthy, clean and aerobic
The new tank syndrome what is involved, how develops and when know that it has been established
THE NEW TANK SYNDROME
- NH3 ammonia
- NO2 nitrite
- NO3 nitrate
New biofilters take several weeks to establish
- NH3 levels rise until Nitrosomonas spp begin to reduce NH3
- As NH3 levels decrease, NO2 levels increase until Nitrobacter establish
- As Nitrobacter spp begin to convert NO2 to NO3 the levels of NO2 begin to decrease and the levels of NO3 increase
TANK THAT HAS GONE THROUGH THE CONDITIONING PERIOD NO AMMONIA OR NITRITE
Ammonia toxicity what varies with, what increases toxicity, why is ammonia more toxic than ammonium and the clinical signs in the fish
- Varier with pH and temperature (need to drop pH with ammonia toxicity)
- High temperature increase toxicity (reduce temperature)
- High pH increases toxicity (at first the tank is often alkaline due to water added so need to wait)
- Ammonia NH3 crosses cell membrane easily and enters cells - more toxic
- Ammonium NH4+ does not cross membrane easily - less toxic
Signs in the fish - Depression, anorexia, dull colours, inflammation, excess slime, cloudy eyes
- Blindness, secondary bacterial disease and death
List some ways to reduce ammonia toxicity
- Stop feeding until have no ammonia
- Dilute -> remove and add new water
- Reduce temperature (reduce gill inflammation -> increase O2 consumption)
- Reduce the pH
- Monitor the ammonia levels
- Conditioned gravel
- Ammonia absorbers (carbons, ion exchange resins) - DO NOT RELY ON THIS BY ITSELF
Nitrite toxicity when occurs, clinical signs in fish and ways to reduce
- generally when filters go anaerobic -> stop producing oxygen -> goes backwards in ammonia cycle
Signs in fish - Gulping for air on the surface -> gills are also brown due to methaemoglobin
- Death - rapid mortality
Strategies to reduce nitrite levels - Water changes daily
- Stop feeding
- Add 0.3% salt NaCl - 3 heaped teaspoons to 10L) - FIXES
- Decrease temperature (increase oxygen concertation in the water)
- Chloride is the antidote
- Conditioned gravel
Nitrate overload what level does it need to be below and what does it result in when gets above it
- Not toxic but need to keep below 50ppm
- Changes water to a microbial broth -> opportunistic infections
- Causes immunosuppression due to high organic loads
○ Nitrates, phosphates, bacteria, debris, protozoa, fungi - High organic levels reduce growth rates and suppress the immune system
○ Many fish diseases are associated with high organic levels
What are 7 causes of ammonia and nitrite problems in the established tank
- Increase in fish size or fish numbers -> can overcome the filters ability to break down the ammonia and nitrite
- Medications
- Acid shift -> if correct pH too much (over 7 for ammonia will lead to toxicity)
- Cleaning or replacing filter beds -> if too aggressive can remove all biological filter
- Debris and detritus
- Cessation of water flow through filter -> leads to anaerobic filter
- Anaerobic filter -> leads to backwards flow of cycle -> production of nitrite - nitrite
List the main types of aquarium filters
internal filters, canister filters, ungravel filters, pre-filter (collects the muck on the intake of the filter before hits the filter -> don’t need to clean the filter as commonly)
Marine aquariums what is present in fish only and reef environments and the pH and temperature in each
Fish only - Can contain dead coral, lava rock, coral rubble and shell grit ○ Temperature 24-27 degrees ○ pH - 8-8.4 - IMPORTANT Reef environments - Can contain live coral, live rock, crabs, shrimps ○ Temperature 24-17 degrees ○ pH - 8-8.4
pH what are the preferred rangers for acidophile, most fish, alkalinophiles, marine and community tanks, how to control the pH
- Acidophile - 6.5-6.8 (tetras, discus)
- Most fish - 6.8-7.4
- Alkalinophiles - 7.4-8 (livebearers)
- Marine - 8.1-8.4
- For community tanks and most shop tanks best to maintain a pH of 6.8-7.0
Acid shifts - pH drops with time
- Must be controlled
○ Partial water changes
○ Filer cleaning
○ Water buffers
○ Neutralizing blocks
○ Shell grit, crushed coral
○ KH-up
General hardness how measured, what increase and decrease with, what levels are considered soft, medium and hard
- Measure of calcium and magnesium
- Increased with
○ Conditioning salts
○ Neutralizing blocks
§ Shell grit, crushed coral - Higher general hardness generally higher pH
- Decreased with
○ Dilution
○ Ion exchange resins
○ Peat moss
○ Remove shell grit, crushed coral - Soft - 50-100ppm (tetras, discus)
- Medium - 100-200ppm (livebearers)
- Hard - 200-500ppm (africans)
