IB Biology Option C - Ecology and Conservation

determining types of stable ecosystems

temperature and rainfall

net production

the amount of energy converted to biomass in an organism always less than gross production because some food is used in cell respiration and he energy released from it is lost from the organism and the ecosystem

feed conversion ratio

the efficiency at which a species uses food: conversion ratio = intake of food (g)/net production of biomass (g) higher ratio = higher respiration rate = lower percentage of ingested energy converted to biomass

comparing pyramids of energy

the most productive ecosystems have high gross production by producers, so large amounts of energy flow to higher trophic levels and there can be relatively large numbers of trophic levels

realised niche

the niche that a species actually occupies

fundamental niche

the niche that a species could potentially occupy

plateau phase

the population has been limited by either: - shortage of resources - more predators - more disease or parasites

distribution of a species

the range of places that it inhabits

gross production

the total amount of energy in food assimilated by an animal or in food made by photosynthesis in producers

ecological niche

the unique role a species plays in a community combination of spatial habitat and interactions

mutualistic relationship

they benefit from each other

symbiotic relationship

they live together

population change calculation

(natality + immigration) - (mortality + emmigration)

cane toads

- introduced to Australia - kills predators with toxins in their skin - produce a large amount of eggs - naturally migrate as adults - spread widely - threaten predators and prey

starlings

- introduced to North America and other areas - compete with endemic species for nest holes and food - damage crops on farms - spread weed seeds in their feces trapping, netting, shooting, destruction of nests/eggs, poisoning = reduces numbers

microbes and the nitrogen cycle

- nitrogen fixation - nitrification - denitrification

phases in population growth curve

1. exponential phase 2. transitional phase 3. plateau phase

terrestrial ecosystems

three main storage compartments biomass (living organisms) litter (dead organic matter) soil

capture-mark-release-recapture (CMRR)

a method used to estimate population size for species of animal that move 1. capture as many individuals as possible in area 2. mark them subtly 3. release all marked individuals back into habitat 4. recapture as many individuals as possible 5. count how many are marked or unmarked estimated population size = (n1 x n2) / n3 n1 = number caught and marked initially n2 = total number caught on second occasion n3 = number of marked individuals recaptured

Gersmehl diagram

a model of nutrient storage and flow for terrestrial ecosystems amount of nutrients in compartment is displayed by the size of the circle size of flow rate is shown by size of the arrows this all differs between habitats

zooxanthellae

a mutualistic photosynthetic algae found in most corals that build reefs

parasitism interactions

a parasite that lives on or in a host, obtaining food from the host and harming it e.g. ticks feed on white-tailed deer as a host

ecological succession

a serious of changes to an ecosystem, caused by complex interactions between the community of living organisms and the abiotic environment

food chain

a single sequence of organisms, each of which consumes the previous one in the chain

competition interactions

a species using a resource reduces the amount available to other species using it e.g. red oak and sugar maple in mixed forests

plastic pollution effect on Laysan albatross

a large marine bird that nests on an island in the Pacific Ocean North Pacific Gyre transports large volumes of macroplastic debris onto beaches adult albatrosses confuse it with food, feed it to their offspring, causing high mortality

transect

a method of sampling at regular positions across an ecosystem to investigate whether the distribution of a plant or animal is correlated with an abiotic variable

biogeographic factors

affect the number of species that live in an area e.g. island size and unbroken forest area

closed ecosystem

an ecosystem that does not exchange nutrients with its surroundings e.g. carbon cycle

plant example of distribution

black mangrove is a tree - inhabits areas with a mean temperature of 20*C ^ - cannot survive cold and frost stress - thrives in waterlogged soils - soil has little to no oxygen - does not survive when soil drys out - tolerates soil pH from 5.3 to 7.8 - tolerates soil salinity up to 90 parts per thousand found in intertidal forests (mangroves) in tropical and subtropical areas, with waterlogged, anaerobic soils and very variable soil salinity

factors which limit algal blooms

bottom-up control or top-down control

periodic disturbance

can be natural in some ecosystems and contributes to biodiversity

biotic index

can be used to obtain an overall environmental assessment of an ecosystem (number of individuals of each indicator species) x (the indicator species' pollution tolerance rating) these values are added together and divided by the total number of organisms = biotic index higher biotic index = less polluted

failed biological control with cane toads

cane toads were introduced to control beetles that had become pests of sugar cane crops toads were unable to climb sugar cane to feed on beetles and instead attacked native insects now toads are a bigger problem than the beetles

eutrophication

causes algae to multiply excessively resulting in an algal bloom

environmental disturbance

causes communities to change, from those predicted by climographs, to other communities

estimating fish stocks

collecting data on catches (number of each age) so spawning rates and survivorship curves can be deduced, from which total population is estimated CMRR methods are inaccurate because the proportion of marked fish that can ever be recaptured is too small echo sounders can measure the size of shoals of fish which aren't swimming too deeply, but trawls must determine the species of fish located

differences between fundamental and realised niches

competition - other species out-compete the species or exclude it in some other way, from occupying it's fundamental niche

biomagnification

concentration of pollutants in the tissues of organisms higher trophic levels reach toxic doses

in situ conservation

conservation of a species in its own habitat e.g. national parks and nature reserves, can involve active management

ex situ conservation

conservationists transfer threatened populations from their natural habitats to zoos, botanic gardens or wild refuges often due to loss of natural bahitat or catastrophic population declines

mutualism in reef-building corals

contain zooxanthellae coral provides alga with protection and holds it close to the water surface so photosynthesis can occur coral's waste products are used by the alga (CO2, ammonia and phosphates) alga provides coral with products of photosynthesis (glucose, amino acids, oxygen) and improves the nutrition of corals symbiotic relationship because they live together mutualistic because they benefit from each other

nitrification

conversion of ammonia to nitrate

nitrogen fixation

conversion of atmospheric nitrogen into ammonia, using energy from ATP

denitrification

conversion of nitrate into nitrogen by denitrifying bacteria

sustainable fishing practices

create a renewable source of food for humans

carrying capacity of the environment

maximum population size that can be supported by the environment

mutualism interactions

different species living together in a close relationship, from which they both benefit e.g. zooxanthellae and corals

animal example of distribution

dog whelk is a sea snail that can survive out of water for a limited period but not for the lengths of time experienced above the high water neap line - saline water - tolerate limited salinity increases above 35 ppt - cannot tolerate large salinity increases - requires mean temperature from 0*C to 20*C - survives some wave action by clinging to rocks - cannot survive battering on very exposed shores - found in lower to middle parts of rocky shores

conservation of the Mauritius kestrel

dropped to a population of four individuals due to loss of habitat, invasive alien species and DDT pollution a captive breeding centre was establish eggs were removed from nests hatched in incubators reared and taught to catch prey reintroduced to the wild population recovered gradually

pollution tolerance ratings examples

stonefly nymphs - need unpolluted, well oxygenated water - rating of 10 rat-tailed maggots and tubifex worms - thrive in low oxygen levels with much suspended organic matter - rating of 0 all freshwater invertebrates have a rating 1 - 10

active management

e.g. control of alien species

climax community

ecological succession stops when a stable ecosystem develops with a group of organisms called a climax community

random number generator

ensures that sampling of populations is free of bias

human activity and the nitrogen cycle

fertilisers containing nitrates and ammonium are produced by the Haber process from gaseous nitrogen --> runoff from fields results in raised nitrogen concentrations in rivers and lakes nitrogen oxides from vehicle exhausts dissolve in water and in the atmosphere to form nitrates --> deposited in rainwater extra deposits = algal blooms & eutrophication

natural environmental disturbance

fires floods storms

gyres

five areas where a huge amount of plastic has accumulated in marine environments

keystone species

has a disproportionate effect on the structure of an ecological community. some are the direct or indirect food source for most other species in a community some are predators that have major effects on limiting population sizes of their prey conservation of keystone species is essential for the conservation of an ecosystem

biodiversity

has two components: richness and evenness moderate populations = most diverse

evenness

how close in numbers the different species are

interactions

how the species affects and is affected by other species in the community, including nutrition

biochemical oxygen demand (BOD)

increases when bacteria decompose dead algae from algal blooms, using oxygen taken from the water if oxygen levels drop very low, other aquatic animals die

Simpson's reciprocal index of diversity

measures biodiversity in an ecosystem can be used to compare ecosystems 1. random sampling technique to search for organisms in the ecosystem 2. identify organisms found 3. count total number of individual species 4. calculate the index: N(N-1)/sum of n(n-1) N = total number of organisms n = number of individuals per species

human environmental disturbance

introduction of alien species logging of forests land drainage

macroplastic debris

large pieces of plastic which eventually degrade into microplastic debris

maximum sustainable yield

largest amount that can be harvested without a decline in important to know the age profile, reproductive status and size of population

measuring biomagnification

level of toxin measured in each organism of the food chain and in the environment, so concentration factors can be determined tissue from top carnivores that are found dead is tested = source of pollutant is located

plastic pollution effect on lugworm

lives on muddy sea shores in Europe and North America, ingests mud and digests organic matter ingests microplastic contaminating mud = harmful microplastic can contain toxic additives and accumulates hydrophobic toxins from sea water also harms other animals due to biomagnification

DDT pollution and malaria

malaria is transmitted by mosquitoes insecticide, DDT, was sprayed onto water with mosquito larvae = malaria became less common DDT killed other insects and top carnivores through biomagnification = DDT banned malaria levels rose again = controversy

population size change factors

natality - offspring produced mortality - individuals lost from population immigration - individuals moving in the area emigration - individuals moving out of the area

endemic species

naturally occurs in an area

indicator species

needs particular environmental conditions and therefore shows the conditions in an ecosystem e.g. lichen vary in their tolerance of sulphur dioxide so can be used to assess the concentration of this pollutant in an area

richness

number of different species present

open ecosystem

nutrients flow between the three compartments in a terrestrial ecosystem, and also flow to and from these compartments and the surroundings

phosphate fertilisers

obtained from rock deposits, which are quite scarce and phosphate availability may limit agricultural crop production in the future

phosphorous cycle

plants absorb phosphate from the soil for production by photosynthesis of compounds with phosphate groups phosphate is released back into the soil when decomposers break down organic matter rate of turn over is much lower than nitrogen cycle phosphorous is added by application of fertiliser phosphorous is removed by harvesting crops

limits of distribution

plants and animals are limited in their distribution by abiotic factors - limits of tolerance & zones of stress

transitional phase

population growth slows carrying capacity of environment is reached natality rate falls mortality rate increases

exponential phase

population increasing rapidly natality rate > mortality rate immigration > emigration resources are abundant diseases and predators are rare

predation interactions

predators benefit as they feed on prey, which affects numbers and behaviour of prey e.g. coyotes are predators of white-tailed deer

herbivory interactions

primary consumers feed on plants or other producers, which harms producers but reduces competition between producers e.g. monarch butterfly caterpillars feed on milkweed

example of biomagnification

radioactive isotope caesium-137 was released by the Fukusima nuclear disaster levels of it were found in marine food chains killer whales reached levels 13000 times higher than phytoplankton at the start of the food chain

concentration factors

ratios between the level of toxin in two organisms or between one organism and the environment

example of primary succession

retreating glaciers in Iceland = leaves areas of sand, gravel and clay then colonised by animal and plant species

climograph

shows the relationship between temperature and rainfall and types of stable ecosystems

edge effect

some species avoid the parts of forest close to an edge, so are absent from fragmented forests

characteristics of primary succession

species diversity - increases (some die out, but more join) plant density - increases (measured with leaf index) organic matter in the soil - increases (more dead leaves, roots and matter from plants) soil depth - increases (as the organic matter helps bind the mineral matter together) water-holding capacity of soil - increases (due to increased organic matter) water movement - speeds up (due to soil structure changes - more drainage) soil erosion - reduced (due to binding action of roots of larger plants) nutrient recycling - increases (due to increased storage in soil and the biomass of organisms)

primary succession

starts in an area where living organisms have not previously existed e.g. new island created by volcanic activity

alien species

type of organism that humans have introduced to an area where it does not naturally occur often become invasive because predators from their natural community, that would control their numbers, are not present unless adapted to an ecological niche which has not been exploited yet, these species will compete with endemic species and may cause them to become extinct due to competitve exclusion

biological control

use of a predator, parasite or pathogen to reduce or eliminate a pest e.g. successful with pests of crops grown in greenhouses

conversion ratios

used to asses the sustainability of food production practices. Typical ratios for meat production: salmon in fish farms = 1.2 chicken in broiler houses = 1.9 pork reared in housing = 2.7 beef reared on a feed lot = 8.8 birds and mammals have higher respiration rates because they maintain constant body temperatures so their FCRs are relatively high

food web

used to show all the possible food chains in a community

eutrophic

water with high concetrations of nitrate and phosphate ions

waterlogged soils and nitrogen cycle

waterlogged soils have low oxygen prevents production of nitrate by nitrifying bacteria, and causes nitrate is then converted to nitrogen gas by denitrifying bacteria therefore waterlogged soils are deficient in nitrate, plants show deficiency through yellowed leaves insectivorous plants overcome deficiency by absorbing ammonia released from digesting insects

top-down control

when large populations of herbivorous animals in the water feed on algae, limiting it's populations limited by predators or parasites

bottom-up control

when shortage of nutrients in the water limits the growth of algae limited by the carrying capacity

competitive exclusion principle

when two species have an identical niche, then one species is the superior competitor and causes the other to be lost from the ecosystem

spatial habitat

where the species lives

species with an identical ecological niche

will compete in all aspects of life, until one is the superior competitor and causes the other to be lost from the ecosystem = competitive exclusion principle

species with a similar ecological niche

will compete in the overlapping parts of the niche e.g. breeding sites or food are usually able to coexist as long as they do not compete in other/all ways