Water pollution W2

Biological pollutants

Invasive alien species are considered…

the second greatest threat to global biodiversity after habitat loss (Earth Summit, Rio Convention 1992)

Cichlid family (fish) vs. Nile Perch

Endemic to three East-African lakes (Lake Victoria, Tanganyika, Malawi).

Three stage radiation allowed evolution of ecological + phenotypic diversity within a rapidly multiplying lineage.

1st stage: divergence of lineages into different major habitats

2nd stage: morphological specialisation - trophic differentiation within habitats.

3rd stage: sensory communication diversification

Intro of Nile Perch lead to loss of many endemic species, as it is a predator.

Future for lake Victoria now bleak.

Economics of Lake Victoria

Largest freshwater fishery in the world.

Major source of revenue in Tanzania, Kenya, + Uganda.

Uganda only country to enforce official controls on exploitation, + each factory must follow export quota.

Exports of fresh Nile perch have developed over last 5 years (long shelf life).

introduced species

organism not native to the place or area where it is considered introduced and instead has been accidentally/deliberately transported to the new location by human activity.

IUCN 2000 definition

“An alien species which becomes established in natural or semi-natural ecosystems or habitat, is an agent of change, and threatens native biological diversity”.

Invasive species

• establishes successfully

• reproduces successfully (rapidly, fecund)

• capable of spreading efficiently

• damaging

Japanese Knotweed (invasive species)

Introduced to UK in early 19th century by botanist, due to ornamental appearance.

It outcompetes other wildlife for water, light, + nutrients - hence destructing biodiversity.

Also causes damage to pipework, paved areas, tarmac + underground infrastructure.

Intro of non-native species in US

Over 50,000 species introduced —> $137 billion in damages each year.

About 42% of species on Threatened or Endangered species lists are at risk primarily because of non-indigenous species.

Direct impacts of invasive species

Disease, Predation, Hybridisation, parasitism, health hazard, Competition (interference).

Indirect impacts of invasive species

habitat alteration, economic loss, + competition (scramble)

Resource competition (scramble)

Number of organisms utilise common resources that are in short supply.

All individuals equally affected, no winners or losers.

Interference competition

Organisms seeking a resource harm one another in the process, even when resources are not in short supply.

There are winners and losers.

Ecological impacts depend on:

• the invading species

• extent of invasion

  • vulnerability of the recipient ecosystem

Hybridisation impacts

Interactions between invasive + native species during reproduction can result in severe impacts on native.

Erosion of native gene pools can lead to sterile offspring + decrease in population size

e.g. impact of invasive alien Mallard and New Zealand Grey duck

White clawed crayfish

Local distribution affected by availability of habitats and water quality.

Species in rapid decline due to releases of non-native crayfish e.g., Signal Crayfish, which was introduced for farming purposes and carries the crayfish plague.

economic impacts of non-native species introduction

• US economic costs through damage to agriculture, forestry, fisheries, and other human enterprises estimated $137 billion per year.

• Sea lamprey not controlled —> economic costs > US$ 500 million per year

• Zebra mussel impact to Great Lakes = US$ 1 billion

• Dutch elm disease costs Canadian economy $150 million

• estimated that rabbits cost Australian farmers over $600 million annually in lost production

2 types of economic impacts

Market impacts (e.g., change in prices)

Non-market impacts (e.g., changes in ecosystem services)

Ecosystem susceptibility to invasion

1. suitable climate + habitat relative to invading species

2. limited assemblage of resident species = most susceptible to invasion . Lack of resident species decreases the number of potential competitors + predators.

3. probability that the species will successfully establish influenced by ecosystem

(island ecosystems more susceptible due to few predators + competition)

key traits of invasive species

• weediness - species that can grow to reproductive maturity quickly + produce lots of highly dispersing offspring

• strong competitor

  • ability to alter ecosystem e.g., nitrogen fixation

What has increased the likelihood of intentional/unintentional non-native species?

Rapid increases in volume of international trade + tourism

Sources of invasive species release for water/watersheds

ballast water, vehicular transportation, escaped ornamental plantings, fishing bait releases, illegal stockings, aquaculture escapes

pathways of entry of non-native species (unintentional)

1. transported commodities in commerce/international freight

2. ballast water, + hull fouling

3. passenger’s belongings, baggage, clothing

4. habitat alterations / canals

5. recreational activities

New Zealand flatworms

They prey on earthworms in UK —> deterioration of soil structure.

Believed to spread principally through movement of plant material + soil.

Zebra mussel

Brought into the Great Lakes, possibly on hulls or in ballast water of vessels from Europe. They filter out nearly all the phytoplankton and remove most of the food for filter feeders + microscopic zooplankton, which in turn supports larval + juvenile fish.

Habitat alterations/canals

Man-made canals + diversions have facilitated the intro of several fish species + some plants. Can accelerate spread of unwanted species.

pathways of entry of non-native species (intentional)

1. agriculture + horticulture

2. aquaculture

3. aquarium / ponds / amenity water

4. forestry

5. wildfowl + game stocking

6. fur farming

7. biological control

8. species conservation / education

9. research

   1. pets, collection + domestic animal ( escape, release)

Rhododendrons

Scottish botanist amassed hundred of species of rhododendron, and other shrubs. Brought back c. 31,000 plant specimens.

Salmon farming in west coast of Scotland + Ireland

Cages consist of Atlantic salmon, which is native to UK, but the strains are not native, usually from Norway. Many concerns of environmental impacts (e.g., parasites + disease, genetic pollution, hybridisation )

Canadian pondweed

Invasive ornamental aquatic plant introduced to UK.

Forestry

Intro of fast growing non-native species such as European larch, Norway spruce, western hemlock.

Cane Toad

Example of biological control. Introduced to control pest species but have overpopulated Australia.

how to protect ecosystems from invasive species?

Intact ecosystems are best preventative measure against invasive species.

Safeguarding introductions

1. identify the risk e.g., potential pathways of intro

2. develop + use ‘codes of conduct’ to reduce this risk

strategies for pathway closure

1. interception of invasive species; regulations enforced with inspection + fees

2. treatment of material suspected to be contaminated with invasive species

3. prohibition of particular commodities in accordance with international regulations

4. public education to support prevention of introduced species

public awareness campaign DEFRA

Gyrodactylosis serious fish disease that infects skin, gills and fins of salmon, trout and other freshwater fish.

ballast water management

1. ballast water management

2. chemicals e.g., biocides, oxidising agents, non-oxidising biocides, ozone

3. heat treatment e.g., maintain water temp 35-45 degrees celsius

4. filtration e.g., filter water before it enters tank or as it is discharged

   1. UV treatment

MAF Biosecurity New Zealand

Charged with leadership of biosecurity system. There to keep out, remove, or effectively manage the harm that pests or diseases can do to our economy, the environment and our health.

Invasive species specialist group (ISSG)

aims to reduce threats to natural ecosystems and the native species they contain by increasing awareness of invasive species, and of ways to prevent, control or eradicate them.

Wildlife and Countryside Act 1981

Offence to release or allow to escape, any non-native animal to the wild in Great Britain except under license issued by DEFRA. But does not place same restrictions on animals native to one part of country being moved outside their natural range.

EA banning use of live bait

Bans use of all freshwater fish as live bait or as dead bait in 14 of Great Lakes in Lake District. Anglers who don’t comply could face fines of up to £2,500.

EU ban wild bird trade

Made to limit spread of disease (e.g., bird flu)

Early detection

To detect invasions it is important to have baseline surveys + consistent monitoring programs in place. But monitoring expensive + time consuming.

Monitoring difficult if:

1. lack of financial resources

2. lack baseline data (how to monitor non-native of native species have yet to be described)

3. lack legal requirements to monitor or control

Key components of early detection:

• community awareness + outreach

• instruction of volunteer community support - preventative technique + control measures

• communication of health and ecological risks associated with technique + measures

• community support + political will

• clear lines of authority for appropriate actions

• decision support tools

• monitoring of outcomes + analysis of success and failure

eradication

1. analysis of barrier to success + incentives

2. analysis of co-operation between countries in transboundary systems

3. engage local community

4. record results of attempted eradication

Coypu eradicated from East Anglia 1989

Introduced to fur farms in 1930s from South America. Early escapes, and they established in East Anglia, but a severe winter in 1946/47 killed most off. They dig large holes in banks + dykes, and also damage root crops. MAFF started campaign to limit Coypu to Norfolk Broads in their ‘heartland’. This only lead to increased spreading so resulted in eradication.

goals to control invasive species

1. contain species within geographic range

2. suppress the overall abundance down to some predetermine level

Mechanical control

• highly specific

• labour intensive

e.g., cutting trees, Lamprey trap (water)

Chemical control

• effective in short term

• high cost

• often effects natives

• health concerns

e.g., lampricides

Biological control

• cost effective

• permanent

• self-sustaining

e.g., release of sterile males that outcompete wild individuals

the next generation of control: genetic tools

• gene editing - identify a gene that could reduce fitness + insert into genome of invasive species

• gene drive - genetic engineering propagates a particular suite of genes throughout a population by increasing probability that an allele will be transferred to offspring