Human-mediated and natural dispersal of invasive species: implications for watershed-

scale management practices

Thomas HorvathBiology Department

State University New YorkCollege at Oneonta

Linkages:Lentic-lotic links

Human-invasive species links

Weekly World News, August 1993

“Non-native species cause $123 to 137 billion in damage annually – more than twice the annual economic damage caused by all natural disasters in the US.”

D. Pimentel24 Jan, 1999 AAAS

Source: Precious Heritage: The Status of Biodiversityin the United States© The Nature Conservancyand NatureServe

100

80

60

40

20

0

HabitatDegradation/

Loss

Exotic/InvasiveSpecies

Pollution

Overexploitation

Disease

%Sp

ecie

s Aff

ecte

d by

Cau

se (n

=1,8

80)

“Invasive species and their environmental damage are the most irreversible form of pollution.”

David LodgeChair, National Invasive Species Advisory Committee

Dreissena polymorpha (Pallas)

Economic Impacts

Ecological Impacts

Direct impact on native Bivalves

Freshwater Mussel DiversityFamily Unionidae

Source: Precious Heritage: The Status of Biodiversityin the United States© The Nature Conservancyand NatureServe

FreshwaterMussels

Crayfishes

Amphibians

Fishes

FloweringPlants

Conifers

Freshwater

Butterflies/

Damselflies

Ferns

Reptiles

Dragonflies/

Tiger Beetles

Skippers

Mammals

Birds

Critically Imperiled

Presumably/Possibly Extinct

Imperiled

Vulnerable

0% 10% 20% 30% 40% 50% 60% 70%

Proportion of Freshwater DependentU.S. Species at Risk

Dispersal Mechanisms

Adult musselVeliger

Lentic – Lotic Linkages

Passive Dispersal

Distance from Lake-Outlet (km)

Velig

ers

L-1

2003

0 2 4 6 8

02468

10121416

2004

0 2 4 6 80

1

2

3

4

5

Eaton Brook

Distance from Lake-Outlet (km)

Velig

ers

L-1

2003

0 5 10 15 20 250

2

4

6 2004

0 5 10 15 20 250

2

4

6

Oaks Creek

Eaton Brook

Distance from Lake-Outlet (km)

Velig

ers

(mill

ions

day

-1)

0 2 4 6 8

0

20

40

60

80

100

120Oaks Creek

0 5 10 15 20 25

0200400600800

10001200140016001800

Veliger Flux (2003)

Linkages due to Human Behaviors

Boater Survey ResultsEaton Brook Reservoir

• Estimated 1635 recreational visits to EBR

• 98% of boaters have heard of zebra mussels

• 32% of boaters don’t know how to prevent the spread of zebra mussels

224 survey points126 interviews

Boater Survey ResultsEaton Brook Reservoir

• 55 boaters had used their boat in a nearby ZM lake within past week

• 20% of all boaters were moving to another non-ZM lake within a week

Boater Survey ResultsEaton Brook Reservoir

• 14% of boaters had aquatic plants on their boat after as they were leaving

• 6% of boaters had live zebra mussels on their boats

Boater Survey ResultsEaton Brook Reservoir

• 14% of boaters had aquatic plants on their boat after as they were leaving

• 6% of boaters had zebra mussels on their boats

1635 boat trips x 6% w/ zm

≈ 100 boaters transporting live zebra mussels in 2004

What Can We Do?

Zebra Mussels (Dreissena polymorpha) in the Chesapeake Bay Watershed:

A Regional Management Plan

• Goals1. Stop the further spread of zebra mussels by

identifying strategies and partnerships necessary to control the spread of mussels

2. Eradicate zebra mussel colonies in the Chesapeake Bay watershed where possible

ChesapeakeBay Program

Invasive species management plans recommends:

• public outreach programs• monitoring programs• rapid response strategies• possible eradication methods • actions and funding needs to implement each of

the recommendations

Kolar & Lodge 2001

Species entrained in transport pathway

Survives transport & introduction

Establishment

Spread

Fails in transport

Fails in establishment

Noninvasive

Invasive

Otsego LakeCooperstown, NY

Ending Thoughts

• Lakes serve as sources for further invasions

• Models suggest the “stitch in time” approach makes sense

Policy makers should be informed of the benefits of prevention programs from the standpoint of both reducing species invasions other than the targeted species, as well as the economic benefits associated with avoiding potential future direct and indirect costs of unchecked invasion, control, or elimination.

Horvath. 2008. Economically viable strategy for prevention of invasive species introduction: Case study of Otsego Lake, New York. Invasive Species 3(1): 3-9.

Thank Youhorvattg@oneonta.edu

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