Effects of biological invasions on large-river ecosystems

Effects of biological invasions on large-river ecosystems Effects of biological invasions on large-river ecosystems - Start

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Effects of biological invasions on large-river ecosystems - Description

Dave Strayer, Cary Institute of Ecosystem Studies. Conclusions. Like other threats being discussed here. Biological invasions have large, varied effects on large-river ecosystems and the services they provide to people. ID: 564877 Download Presentation

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Effects of biological invasions on large-river ecosystems




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Presentations text content in Effects of biological invasions on large-river ecosystems

Slide1

Effects of biological invasions on large-river ecosystems

Dave Strayer, Cary Institute of Ecosystem Studies

Slide2

Conclusions

Like other threats being discussed here

Biological invasions have large, varied effects on large-river ecosystems and the services they provide to people

These effects vary enormously across rivers

These effects are increasing over time

Invasions interact with other threats (Havel et al. 2015)

We generally understand the causes of invasions

Unlike other

threats

Much

of this understanding is more qualitative than

quantitative

Effects

of the next invasion are hard to

predict

Invasions

grow on their own, and are long-lasting or

irreversible

Actions

of individual people can have large

consequences

Incorrect

folk wisdom about invasions impedes

control

Current

measures to control invasions are not very

effective

Management

should be matched to the attributes of invasions

Slide3

Hudson example 1: zebra mussels

Strayer, Frontiers Ecol. Environ, 2009

Also blocks water intakes

Controlled in water intakes ($105-106/yr in Hudson, >$300 million in North America)

Slide4

Hudson example 2: water-chestnut

Caraco

et al., Tall et al.

Ecol. Appl., 2011

Slide5

The number of invasions varies hugely

Leprieur

F, Beauchard O, Blanchet S, Oberdorff T, Brosse S (2008) Fish Invasions in the World's River Systems: When Natural Processes Are Blurred by Human Activities. PLoS Biol 6(2): e28. doi:10.1371/journal.pbio.0060028http://journals.plos.org/plosbiology/article?id=info:doi/10.1371/journal.pbio.0060028

But number of invasions ≠ effects

Fish only, so underestimates actual number of invasions

Slide6

The number of invaders rises over time

Mills et al. (1996, updated); Jackson & Grey 2013

But number of invasions ≠ effects

Underestimates actual number of invasions

Slide7

We generally understand causes of invasions

Deliberate releases

(game/food fish, ornamental spp.)

Contaminants of recreational equipment (including water)

Ship fouling

Bait bucket releases

Escapes from aqua/agriculture

Aquarium and water-garden releases

Ballast water

Canals

Slide8

…but not all the important details

Aquarium and water-garden releases

fashion

culturalnorms

educationof owner

availability ofthe species

regulations aboutpurchase and release

economics

?

Slide9

Understanding is more qualitative than quantitative

Propagule

pressure vs. establishment rate

Establishment rate vs. intensity of effects

Spatial variation in effects

Temporal variation in effects

Strength of effects on different parts of the ecosystem

Effects of different kinds of invaders

Context-dependence of effects

Gallardo et al.,

Global Change Biology

(2016)

Slide10

Effect of next invasion is hard to predict

Slide11

Invasions grow on their own, and last for a long time

Dave Brenner, MI Sea Grant

Slide12

Invasions grow on their own, and last for a long time

Dave Brenner, MI Sea Grant

Slide13

Dave Brenner, MI Sea Grant

Invasions grow on their own, and last for a long time

Slide14

Inaccurate folk wisdom is widespread

Invaders go away after a while

Invaders are not bad (or that specific species are good – “zebra mussels clean up the water”)

Natural selection ensures that the best ecosystem results after invasions (the strong survive, and strong is good)

We can eat them or something if they get to be a problem

Slide15

Actions of individual people can have large consequences

Rob

Emens, NC Sea Grant

http://www.dpi.qld.gov.au/extra/aquaticinvaders/add_Overview.html

Slide16

Optimal management should recognize unique attributes of invasions

As long as new invasions are frequent, ecosystems will be unstable, and managers will need to be nimble

Invaders persist and grow once established

Focus on pre-establishment control

Learn how to motivate policy-makers in “preventative ecology”

Focus post-establishment management on specific goals (not “kill ‘

em

all”), and be willing to spend real $$$

Actions of individual people matter

Educate people

Better understand what motivates their behavior

Take decision-making power away from individuals (i.e., remove many more species from commerce)

Slide17

Conclusions

Like other threats being discussed here

Biological invasions have large, varied effects on large-river ecosystems and the services they provide to people

These effects vary enormously across rivers

These effects are increasing over time

Invasions interact with other threats (Havel et al. 2015)

We generally understand the causes of invasions

Unlike other

threats

Much

of this understanding is more qualitative than

quantitative

Effects

of the next invasion are hard to

predict

Invasions

grow on their own, and are long-lasting or

irreversible

Actions

of individual people can have large

consequences

Incorrect

folk wisdom about invasions impedes

control

Current

measures to control invasions are not very

effective

Management

should be matched to the attributes of invasions


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