Aquatic invasive species in inland lakes: Distribution, abundance, impact

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1 Aquatic invasive species in inland lakes: Distribution, abundance, impact Jake Vander Zanden Gretchen Hansen Alex Latzka Center for Limnology University of Wisconsin Madison

2 Acknowledgements A long list of other partners and citizens of WI

3 Invasion of Great Lakes Role of ballast water Poster children Dreissenids sea lamprey

4 the small inland lakes and streams of the basin, and beyond

5 Inland waters Hundreds of thousands of inland lakes and streams Cumulatively they are important: Ecosystem services Inland fisheries Tourism and recreation

6 Inland waters Example: Amount Great Lakes shoreline: 17,549 km Amount of inland lake shoreline in WI: ~51,000 km

7 Great Lakes as a beachhead p

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9 Characteristics of secondary spread A suite of species Relatively slow spread Dispersal and suitability Details vary widely among species Invasion of the Great Lakes is often just chapter 1 of a much larger story

10 Unique management challenge We know which species are of concern Limited number of vectors Overwhelming number of habitat patches Limited resources

11 Smart prevention framework (Spatial risk assessment) Vander Zanden et al Ecol. Appl. 14:

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13 Filter #1 Colonization Are colonists likely to reach a lake? models of boater movements among lakes Presence/absence of boat launch Alex Latzka, Ctr for Limnology

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15 Filter #2 Potential for establishment Environmental suitability Zebra mussel suitability threshold Calcium concentration Papes et al Conservation Biology

16 Filter #3 Localized Impact Poorly understood How variable is it?

17 Application of smart prevention framework: rainbow smelt in WI Basis for prioritizing prevention and management efforts Imperfect, only as good as your understanding and available data Mercado Silva et al Conservation Biology 20:

18 Filter #1: Colonization Can smelt get there?

19 All Lakes N = 5100

20 Can it get there? N = 2200

21 Filter #2: Environmental suitability Can smelt establish a population?

22 Can it get there? N = 2200

23 Suitable N = 530

24 Filter #3: Potential impact on biota

25 Suitable Suitable? N = 530

26 Impact N = 180

27 Smelt Present currently distribution present N = 26

28 Reflecting on the approach Work is built on existing data records How well do we know the actual distribution? Assume invasive species have impact wherever they co occur with gamefish How variable is impact?

29 Reflecting on the approach Work is built on existing data records How well do we know the actual distribution? Assume invasive species have impact wherever they co occur with gamefish How variable is impact?

30 Two fundamental questions: Work is based on existing data records 1) How well do we know the actual distribution? Assume invasive species has impact wherever 2) How variable is impact?

31 Invasive species records A various mix of records from citizens, lake associations, citizen monitoring, counties, DNR, Universities

32 WI DNR infested waterbodies list Collective body of knowledge of the state of existence Presence/absence Keystone component of AIS program

33 What does the infested waterbody list tell us? Species # of Occurrences Eurasian watermilfoil 525 Curlyleaf pondweed 393 Chinese mystery snail 304 Banded mystery snail 179 Rusty crayfish 268 Zebra mussel 116 Total number of AIS populations 1,785 Total number of invaded lakes 1,051 Total number of lakes (>1 ha) 14,497 % of lakes invaded 7% A. Latzka et al. in prep.

34 How well does the infested waterbody list capture reality? UW Madison, DNR, counties: Field survey of 458 lakes Randomized and stratified according to access, conductivity, lake area (9 lake classes) 1) Straight comparison of the infested waterbody list with field survey 2) Extrapolate field survey results to estimate regional invasion rate A. Latzka et al. in prep.

35 How well does the infested waterbody list capture reality? 1) Straight up comparison in the 458 lakes: List: 227/458 lakes invaded (50%) Field survey: 321/458 lakes invaded (74%) A. Latzka et al. in prep.

36 How well does the list capture reality? 2) Extrapolate: A. Latzka et al. in prep.

37 How well does the list capture 2) Extrapolate: reality? For each lake type, multiply proportion of lakes invaded by # of lakes in class, then sum. A. Latzka et al. in prep.

38 How well does the list capture reality? (n=8,004 lakes) the list Estimated rate based on field surveys Zebra mussel 1.1% 1.2% Curly leaf pondweed 4.2% 13.3% Eurasian watermilfoil 5.9% 7.8% Rusty crayfish 3.0% 6.2% Chinese mystery snail 3.6% 18.5% Banded mystery snail 2.1% 15.9% Total 11.9% 39.0%

39 How well does the list capture reality? Take home point: Our landscape is more invaded than we think (>3x) Implications?

40 Two fundamental questions: Work is based on existing data records 1) How well do records reflect actual distribution? Assume invasive species has impact wherever 2) How variable is impact?

41 Abundance indicator of invasive species impact Spatial pattern of abundance for native species 40 Myriophyllum sibiricum (native macrophyte) 30 Frequency Relative abundance

42 Do invasive species follow the same pattern?

43 17 invasive species 105 native species >24,000 abundance estimates note: there are no absence data here G. Hansen et al. in review PLoS ONE

44 Frequency distribution of species abundance Black = invasive Grey = native Fit a Weibull curve to each species (λ and k) Mean values of λ and k for natives and invasives G. Hansen et al. in review PLoS ONE

45 Frequency distribution of species abundance Take home point: Invasive species are usually at low abundances Implications? Frequency Predict which lakes are here Relative abundance

46 Summary Great Lakes as a beachhead ongoing spread to inland waters for generations to come AIS are far more widespread.but often at low abundance Smart prevention: use our collective knowledge of distribution, colonization, environmental suitability, and impact to guide prevention efforts

47 Thanks!

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51 How well does the database capture 2) Extrapolate: reality? Species # of database Estimated # of records occurrences Eurasian watermilfoil Curlyleaf pondweed Chinese mystery snail Banded mystery snail Rusty crayfish Zebra mussel Total invaded: Total # of lakes: 8,004 8,004 % invaded: 12% 39% A. Latzka et al. in prep.

52 These are estimates of how many (what proportion of) lakes are invaded by each species, using the 8004 lakes grouped into classes. Values for records were obtained by dividing known number of invasions by Values for surveys were obtained by summing the products of the rate of invasion for each lake class by the number of lakes in that class Records Surveys Zebra mussel 1.1% 1.2% Curly leaf pondweed 4.2% 13.3% Eurasian watermilfoil 5.9% 7.8% Rusty crayfish 3.0% 6.2% Chinese mystery snail 3.6% 18.5% Banded mystery snail 2.1% 15.9% Total 11.9% 39.0%

53 Impact Impact = R x A x E R=range size (m 2 ) A=abundance (density or biomass) E=effect per unit individual or biomass of invader Parker et al Biological Invasions

54 Impact Impact = R x A x E R=range size (m 2 ) A=abundance (density or biomass) E=effect per unit individual or biomass of invader Parker et al Biological Invasions

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56 Carpenter Lake, Wisconsin, 2006

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58 Filter #1 Which lakes can colonists reach? CHNS project led by Bill Provencher, UW Madison

59 Example: Wisconsin

60 Invasive Species Interactive Mapping System

61 Outline 2. Vast aquatic resources (15k lakes, 40k miles streams), isolated 3. We generally know what the main invasive species are. Many use Great Lakes as a beachhead, spread inland 4. slow spread, due to boaters failure to clean boats. Human behaviors can be modified. Spread can be stopped 5. Motivation/Management goal contain/slow/stop/prevent further spread of known species. How we do this triage, smart prevention