Why Invasions Matter

Transcription

1 Why Invasions Matter A Response to Some Contrarian Claims Anthony Ricciardi Redpath Museum and McGill School of Environment McGill University

2 Nature 474: (09 June 2011)

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4 Three claims by the contrarians Human-assisted invasions do not differ fundamentally from prehistoric ones. (Briggs 2013; Vermeij 2005; Brown & Sax 2004, 2005) Impacts on biodiversity are exaggerated. (Thomas 2013; Schlaepfer et al. 2011; Brown & Sax 2004, 2005) Species origins (native/non-native) are not relevant to conservation management. (Valéry et al. 2013; Davis et al. 2011)

5 Counter claims, supported by evidence 1. Modern invasions are a unique form of global change. 2. Invasions erode biodiversity and disrupt ecosystems. 3. Species origins matter, because evolution matters. 4. Higher invasion rates render ecosystems more difficult to manage.

6 Two opposing views of modern invasions A) Modern invasions = nothing new The magnitude & impacts of human-assisted invasions are similar to those in the fossil record. (Vermeij 2005; Brown & Sax 2004, 2005) Great American Faunal Exchange (3 million years ago)

7 Two opposing views of modern invasions A) Modern invasions = nothing new The magnitude & impacts of human-assisted invasions are similar to those in the fossil record. (Vermeij 2005; Brown & Sax 2004, 2005) B) Modern invasions = unprecedented global change The current mass invasion event is unique in scale and impact. (Ricciardi 2007; Cassey et al. 2005)

8 Colonization of the Great Lakes by invaders from the Black Sea region

9 American comb jellyfish (Mnemiopsis leidyi) in the Black Sea Anchovy catch (10 3 tons) Decline in Black Sea anchovy Mnemiopsis expansion Year

10 Origins of non-native species in the Baltic Sea (~130 species in total) 12% 25% 27% 11% 16% Data from Baltic Sea Alien Species Database

11 New Zealand

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13 Galapagos Gough Isld Hawaii Australia Great Lakes Caspian Sea Black Sea Species per year Estimated rates of invasion for various regions 100 Prehistoric Ricciardi (2007)

14 Galapagos Gough Isld Hawaii Australia Great Lakes Caspian Sea Black Sea Species per year Estimated rates of invasion for various regions Prehistoric Modern Ricciardi (2007)

15 Global transportation systems Globaia.org

16 Enormous numbers of organisms are moved through global shipping 3-10 billion tonnes of ballast water moved annually. 1 liter contains: thousands of plankton, millions of bacteria & billions of virus particles. >5000 species carried by ships at any time. Ballast water being released from a cargo ship

17 .and through live trade Smith et al. (2008) Conservation Letters 1: billion live fishes imported into U.S.,

18 Differences between natural/prehistoric and human-assisted invasions Natural invasions Human-assisted invasions Frequency of long-distance Very low Very high dispersal events Invasions between Rare Common biogeographic realms Numbers transported Usually small Potentially enormous Mass colonization Episodic, regional Global, ongoing Potential for synergies Low Very high with other stressors

19 Counter claims, supported by evidence 1. Modern invasions are a unique form of global change. 2. Invasions erode biodiversity and disrupt ecosystems. 3. Species origins matter, because evolution matters. 4. Higher invasion rates render ecosystems more difficult to manage.

20 Proportion of modern animal extinctions in which invasions were a causal factor Global animal extinctions: IUCN Red List: Bellard et al (62%); Clavero & Garcia-Berthou 2005 (54%) 54 62% Global fish extinctions: AMNH database: Harrison & Stiassny 2004 Global mammal extinctions: AMNH database; McPhee & Flemming 2004 (48%) IUCN Red List: Bellard et al (69%) Global bird extinctions: Birdlife International 2000 (50%) Bellard et al (60%) Global reptile extinctions: Bellard et al % 48 69% 50 60% 57%

21 Near total extinction of the American chestnut by chestnut blight fungus from Asia 800 million chestnut trees destroyed in ~50 years

22 Science (2011) 332: From : 6 million bats killed by White Nose Syndrome in N. America

23 Impact of Varroa mites on honeybees parasites native to southeast Asia invaded western Europe, U.K., N. America, S. America, N.Z., Hawaii destroyed most wild honeybee colonies in the U.S. Mites on honeybee pupa

24 Non-native plants are 40 times more likely to be invasive than native plants Number of species <0.3% Non-invasive Invasive % 2000 Simberloff et al. (2012) 0 Natives Non-native

25 Non-native consumers cause more damage to prey populations than do native consumers Effect on native populations log e (X consumer / X control ) Stronger negative impact P < n= n=44 Native Non-native Consumer origin Paolucci, MacIsaac & Ricciardi (2013)

26 Invasion of Guam by the Brown Tree Snake (Boiga irregularis) Invasion of Lake Victoria by the Nile Perch (Lates niloticus) Caused 16 extinctions (birds, lizards, bats) Caused ~ spp extinctions (endemic cichlids)

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28 Frog abundance % lakes containing frogs Impact of exotic trout on frogs (Rana muscosa) in alpine lakes in California Knapp et al. (2001)

29 Frog abundance % lakes containing frogs Impact of exotic trout on frogs (Rana muscosa) in alpine lakes in California Knapp et al. (2001)

30 Evidence from invasive species eradications

31 The effect of Peacock Cichlid Cichla ocellaris on the food web of Lake Gatun, Panama herons & kingfishers adult Cichla young Cichla terrestrial insects phytoplankton benthic algae Before introduction After introduction Zaret & Paine (1973) Science

32 Number of mosquitoes Seasonal abundance of malarial mosquitoes near Lake Gatun Post-invasion 1968 Pre-invasion 0 Zaret & Paine (1973) Science Month

33 Counter claims, supported by evidence 1. Modern invasions are a unique form of global change. 2. Invasions erode biodiversity and disrupt ecosystems. 3. Species origins matter, because evolution matters. 4. Higher invasion rates render ecosystems more difficult to manage.

34 Number of high-impact species Number of high-impact invaders versus total number of invaders in aquatic systems 30 Y = 0.10 X R 2 =0.85, p= Ricciardi & Kipp (2008) Total number of invaders Slope = 0.10 ± 0.02 (95% C.L.)

35 Hypothesized transfer of botulism from invasive mussels to birds in the Great Lakes Impact: >100,000 fish-eating birds killed since Cause: Type-E botulism Round goby Waterfowl Zebra/quagga mussels Clostridium botulinum

36 Cumulative number of invaders Rate of discovery of invaders in aquatic systems Great Lakes Ricciardi (2006); GLANSIS (2012) Baltic Sea Baltic Sea Alien Species Database San Francisco Bay 100 Carlton & Cohen (1998) 90 CIESM (2005) Mediterranean Sea

37 Expected Number of Synergistic Disruptions Predicted consequence of an unrestrained invasion rate Number of Invaders

38 Expected Number of Synergistic Disruptions Predicted consequence of an unrestrained invasion rate Number of Invaders

39 In this worldwide pooling of faunas and floras, some species get out of bounds as pests and disease, others are extinguished. Aldo Leopold, The Land Ethic, 1949