river wars: influx of zebra mussels in the hudson river watershed

River Wars: Influx of Zebra Mussels in the

Hudson River WatershedBy: Jason Aguirre and Soon il Higashino

Ossining High School

http://allaboutlemon.com/art-game/ag-w51-underwater-tower/

http://www.fws.gov/midwest/endangered/images/mussels/higginseye/HigginsEyeWithZebraMusselsByUSFWS.jpg

http://www.biodrawversity.com/images/photos/ZebraMussel.jpg

Introduction

● The data used were obtained from scientists at the Cary Institute of Ecosystem Studies

● The data included information about zebra mussel populations, the relationship between zebra mussels and other organisms of the Hudson River watershed, and the relationship between zebra mussels and water chemistry


Introduction

● Data were collected from freshwater tidal Hudson (River Kilometer (RKM) 99-248) or (River Mile (RM) 61.5-154.1)

● Data were collected from the years 1987 to 2005


http://www.dec.ny.gov/images/remediation_hudson_images/hrwmap750.jpg

Data Trends

● We observed that, other than the sudden increase in 1993, the populations seem to fluctuate steadily: increasing, then decreasing, then increasing

Data obtained from scientists at the Cary Institute of Ecosystem Studies


Data Trends

● We observed that unionid populations somewhat followed zebra mussel populations from 1992 to 1996; then the populations tended to remain low and stable

● The zebra mussel and unionid mussel density have a moderate positive correlation


r-value: 0.70 N = 14p-value: 0.0052

Zebra Mussel Density (#/m2)

Uni

onid

Mus

sel D

ensi

ty (#

/m2)


Data Trends

● We observed that copepod populations were somewhat inversely related to zebra mussel populations; as zebra mussel density increased, copepod numbers decreased

● The copepods and zebra mussel density have a weak negative correlation

r-value: -0.46N = 19.00p = 0.05


Zoop

lank

ton:

Cop

epod

s (#

/L)



Data Trends

● We observed that zebra mussel density and water transparency did not have a strong correlation with each other

● Water transparency appears to be generally higher in the absence of zebra musselshttp://allaboutlemon.com/art-game/ag-w51-underwater-tower/

r-value: -.11 N: 16p-value: .68


Wat

er T

rans

pare

ncy

(m)


Data Interpretation: Population● The population swings observed in zebra mussel populations may

possibly be attributed to changes in environmental conditions (water and weather)○ Most of the zebra mussel’s predators live in Europe; only some

fish and duck species in North America have been known to prey on them

○ More information on water temperature, dissolved oxygen, weather forecasts, etc. may help us better understand factors that may influence the susceptibility of zebra mussels to population fluctuations


Data Interpretation: Other Organisms ● In 1994, unionid populations suffered severely after the boom in

zebra mussel populations in 1993, supporting literature that has found zebra mussels to be responsible for massive unionid declines (Schloesser, Nalepa, and Mackie 1996)○ Suggests that the negative effects that zebra mussels have on

unionid populations may exacerbate population declines in other local organisms, such as zooplankton or phytoplankton

● Copepod populations demonstrated that zebra mussel populations may be thriving at the expense of other organisms in the watershed


Data Interpretation: Water Chemistry● Surprisingly, we did not observe a significant correlation between

zebra mussels and water transparency○ Previous research has suggested that zebra mussels help

increase light availability (Caraco et al. 1997), contrasting with the data analyzed

● This may suggest that even though they are known to filter feed and increase water transparency, zebra mussels may not always provide many beneficial effects on the environments that they invade


Questions and HypothesesQuestion: Is it plausible for zebra mussels to coexist with unionids and native mussels in the Hudson River watershed?Our Hypothesis: Yes, as suggested by Strayer and Malcom in 2007, it is plausible for zebra mussels and native species to coexist: four native populations have already started to stabilize after declining

(Strayer and Malcom 2007)


Questions and HypothesesQuestion: Does the presence of zebra mussels benefit native organisms in any way? If so, how?Our Hypothesis: Yes, by allowing water transparency to increase, organisms that use sunlight, such as phytoplankton, are able to thrive due to the increased clarity


http://www.seagrassli.org/ecology/physical_environment/Lt/light-attenuation-kp.gif

So… why a short film?We used a short film in order to convey the concept of invasive species through a visual and relatable medium. Our story takes place in a high school because many people can relate to this setting. High schools can be compared to aquatic ecosystems because of the many unique and diverse “niches” or roles within the school (ex: principal, teacher, students, etc.). Because of these niches, we chose a high school setting in order to demonstrate how an invasive species can disrupt the different niches within an ecosystem. This story follows the initial zebra mussel through the process of invading a habitat (arrival, niche finding, populating, and integrating).


References● Data were analyzed from data sets compiled and provided by the Cary Institute of

Ecosystem Studies● Caraco, Nina F., et al. “Zebra mussel invasion in a large, turbid river: phytoplankton

response to increased grazing.” Ecology 78.2 (1997): 588-602.● Schloesser, Don W., Thomas F. Nalepa, and Gerald L. Mackie. “Zebra mussel infestation

of unionid bivalves (Unionidae) in North America.” American Zoologist 36.3 (1996): 300-310.

● Strayer, David L., and Heather M. Malcom. “Effects of zebra mussels (Dreissena polymorpha) on native bivalves: the beginning of the end or the end of the beginning?.” Journal of the North American Benthological Society 26.1 (2007): 111-122.


river wars: influx of zebra mussels in the hudson river watershed

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