parasites Flashcards
define parasitism
relationship between two species where one species (parasite) benefits at the expense (unkosten) of the other (host).
what is the difference between a macro and a micro parasite?
macropasite= you can see them micro = you dont
give an example for a group of macroparasite
crustaceans, nematodes
give an example for a group of microparasite
protozoa, fungi, bacteria, viruses
what is an ectoparasite?
a parasite whcih lives on the oustide of the host
what is an endoparasite?
a parasite which lives inside the body of the host
endoparaistes are divided into? - what is difference between these two groups ?
intercellular: inside body cavities of the host
intracellular: inside cells of the host
what are parasites called that depend on the host to complete its life cycle?
obligate parasites
what are the parasites called that do NOT depend on the host to comlete its life cycle?
facultative parasites
what is and indirect parasite
a parasite which has multiple hosts (multiple life stages).
- at least one or more intermediate and one definitive host
what is a direct parasite?
a parasite which only has one host in in his life
what is the difference between a generalist parasite and a specialist parasite?
a generalist can live on any host- not specialized on one species.
a specialist only has few species, on which he can live on.
what are some problems with estimating marine parasites?
- effects of depth gradients
- ”-“ of hosts (same paraiste live on different hosts)
- ”-“ latitudinal/longitudinal gradients
- geographical variation
- lack of surveys
- intermediate forms
what is the total estimate of all marine fish parasites?
about 100 000 species
what are some problems in estimating the richness of free living orgainsms
- more than one species concept
- mainly studies on animal kingdom but rarely on microorganisms
what is prevelance?
proportion (verhältnis) of infected hosts among all the hosts examined
what is mean intensity?
mean number (mittelwert) of parasites found in/on the infected hosts.
“host specificity” :
what does it take into account?
takes prevelance and/or intensity of infection into account
does specifity will vary with the number of host species the parasite may live on/in?
yes
si(intensity)
what is the highest number of host specifity?
-what doesn it say abou the host specifity of the parasite?
1
–> parsite only on one host!
Rhodes index of specifity, what does is calculate?
used to calculate how specific a parasite is.
–> “Host specifity “
how can rhodens index of specifity be used to measure site specifity?
by exchanging the number of hosts with number of sites
what is site specifity?
parasites prefer certain microhabitatse over others. specifity varies between species.
give an example for site specifity
two differnet species prefer different sites on the gill (kiemen) of the host.
the number of different parasite species does not effect the site where they live on the organisms .
true or false?
true
the number of the same species does not effect the site where they live on the organisms .
true or false?
false
- same species does affect the site.
do interspecific factors or intraspecific factors effect more the site resitriction of a parasite?
intraspecific factors
ecological concepts: what is equilibrium ?
maintaining the homoeostasis of an ecosystem, stable community.
ecological concepts: what is non-equilibrium ?
competitive exclusion is prevented due to disturbances that prevent a stable community.
parasites:
is equilibrium or on-equilibrium preferred
evidence or both, but non-equilibirum seems to be more prefered.
what is a metapopulation?
likely for parasites or not?
a group of connected population of the same species.
- yes, likely.
give an example for a metapopulation
gyrodactylidae species
lives on salmon and multiplys on it, when getting in contact with other affected salmon, the may jump over – > gene interaction.
what effects can a parasite have on his host?
- changes in behaviour
- changes in the host community (shifts in mean valous of traits)
how does high/low prevelance may affect the normal distribution of a trait in the host community?
high prevelance: displace normal distribution
low prevelance: distribution may become skewed (verschoben)/ shifted
parasite in mariculture -why important?
how can parasites be used ?
- as biological markers –> to differnciate between host populations
- -> used to control introduced species
- as indicator for migration
- used for pollution monitoring –> pulltion indicators
- can be used to monitor ecosystem health
- used to control introduced species
- used
why cas parasites be used for poulltion monitoring?
- more parasites than free living species
- several lifstages –> that are particulary sensitive to environmenatl change
- accumulation of heavy metals , may be higher than in host tissue/environment
- indirect parasites can only survive in habitats where all their hosts can survive (–> indirect ore sensitive)
environmnetal stress can have different effects on the parasites impact on his host.
name a few
- pollution may increase the suspectibilty to parasites
- pollution may decfease parasitsim, by causing higher host mortality
- habitat alteration may lead to incfeased or decreased paraistism
- introduction of new species–> introduction of new parasites; native species might be less resistent to the new parasitses
what are ecosystem services of parasites?
- regulate host abundance–> keeping it under the ecosystem carrying capacity
- -> may allow other species to compete in the same area, creating nisches
- more complex and tight food web –> more resitent
give some examples for parasites and diseases due to parasites in norwegian aquaculture
- “costia” (costyl for salmon industry- ichthyobodea necator causes breathing problems)
- AGD (amobic gill disease)
- whirling disease (codfish&polychaeta, parasite= myoxbolus cerebralis)
- plathelminthes (flatworms) (e.g. bendelmark)
- grodactylus salaris
gyrodactylus salaris:
some facts
- ectoparasite of salmon
- lives in the freshwater base
- feeds on the salmon–> creates osmotic problems
what is a hyperparasite?
a parasite of a parasite
how many norwegian rivers have been infected by gyrodactylus salaris?
- 43 rivers have been infected
- 11 have been cleared
with what can gyrodactylusl salaris be treated with?
rotenone treatment (=insecticide, pesticide, piscicide)
