Assessing the Ecological Risk of the Effects of Climate Change on Zooplankton in Lake Champlain Alex Gibson Mark Rasmussen Ben Sherman Josh Stewart Brittany A. Weldon ENSC 202 Spring, 2009 Daphnia. Spike Walker. 2005© Microscopy UK or their contributors.

Problem: Increasing water temperatures in Lake Champlain due to climate change will alter zooplankton populations and cause subsequent food web disruption at higher trophic levels.

Overview Climate Change Zooplankton in Lake Champlain Trophic cascades and food web Population dynamics Food sources and phytoplankton Predation Invasive species Conclusions & recommendations

Climate Change The Greenhouse Effect: Visible light passes through the earths atmosphere and is either absorbed or reflected into the atmoshphere.

Examples: 1. Comparison of Lakes at Varying Altitudes Characteristics/morphometry determine zooplankton biomass potential. Higher latitudes nutrient deficient. Lower latitudes nutrient rich. 2. Photoperiod influences biomass.

Compensating for increased amounts of greenhouse gases, the mass balance of the earth is disrupted. Compensate managing of inputs and outputs by increasing temperature. Since a thicker blanket of greenhouse gasses have reduced energy loss to space, atmospheric adjustments in the form of temperature increase, have responded to the change.

Implications for the Northeast Unique Characteristics Numerous freshwater ecosystems Dense concentrations of people History of intensive land use practices Extensive Forests *Climate change has the potential to disrupt the dynamic input/output regime agitating natural freshwater systems through the creation of a variety of feedback mechanisms

Effect on Lake Temperature in Lake Champlain Increased global mean temperature Increased seasonal variability Increased cloudiness and precipitation, more runoff More runoff leads to higher base flow warmer water temp.

Zooplankton Microscopic invertebrates Fill a critical niche in Lake ecosystem Principle species in Lake Champlain calanoid copepods, cyclopoid copepods, Daphnia, Bosmina, Sididae,and Leptodoridae Daphnia. (Carling, et al. 2004) Calanoid Copepod Bosmina

Trophic Cascades

Trophic Cascades Definition: suppression of prey abundance as a result of predators in a food web. Factors: Spatial and Temporal -high spatial heterogeneity -deviation from linear food chain -high resource availability and quality

Predictors of Zooplankton Biomass and Community Structure 1. CLIMATE 2. Nutrient Concentration 3. Predation Work in concert to determine lakes trophic state.

Population Dynamics Earlier spring warming Sedimentation Rotifer vs Cladoceran Photoperiod Edible algae Sedimentation

Spring Warming

Dynamics

Sedimentation Rotifer vs Cladoceran Clay interactions

Food Sources Phytoplankton, main food source Increases in phytoplankton growth related to concurrent increases in water temperature (Dale and Swartzman, 1984) Perform at a higher than normal rate of photosynthesis in waters with a higher than optimal temperature

Lake Baikal, Siberia- Monitored since 1945 the world’s largest freshwater lake Monitored since 1945 Dramatic temperature increases Large size of lake- resistance to temperature changes Importance of long-term monitoring

Phytoplankton Biomass Chlorophyll a and Secchi discs used to measure phytoplankton biomass Found to increase 300% since 1979 in Lake Baikal (Hampton, et al, 2008)

Earlier Spring Peak Earlier Spring, high base flow, warmer waters Allows for earlier first peak in phytoplankton growth Longer growing season  Overall increase in phytoplankton biomass - - - Phytoplankton normal conditions, − Phytoplankton in thermally loaded conditions. (Dale, Swartzman, 1984)

Phytoplankton & Zooplankton Herbivorous zooplankton peak follow phytoplankton peak Larger carnivorous zooplankton feed on herbivorous zooplankton Earlier zooplankton peak – phytoplankton, - - - zooplankton (Dale, Swartzman, 1984)

Zooplankton Biomass Decreasing Copepods and Rotifers Increasing Cladocerans Fewer large cladocerans, more smaller (Hampton, et al, 2008)

Zooplankton Decrease in Biomass Mean and minimum values decrease with temperature Maximum values increase  high peak At Max - High variability in Daphnia at high temperatures due to shorter period and larger amplitude (peak) (Norberg, DeAngelis. 1995)

Why are zooplankton decreasing if phytoplankton are increasing? Biomass is decreasing ↓ Larger zooplankton species (Daphnia) ↑Smaller zooplankton species (Bosmina) Warmer water conducive to the growth of…

Blue-Green Algae Growth rate ↑ as water warms Concurrent P overloading ↓ Water clarity, ↓ dO2 Leads to ↓ diatoms & green algae Blue-green lower nutritional value Most zooplankton feed selectively on others …Apparent increase of phytoplankton and decrease in zooplankton

Predation Migration due to predation Predator migration insect larvae of the Notonecta preys on zooplankton in the shallows during the during the day. At night moves to open water to prey on zooplankton

The adult form of the Notonecta also known as the water bug

Migration by zooplankton Zooplankton like Tropocyclops and Polyarhra migrate vertically during day and night. Tropocyclops (copepod) migrate to the bottom of the lake/pond during the day and at night spread equally in the water Known as typical migration

Migration of zooplankton Polyarhra moves to the surface during the day and spread out during the night. Known as reverse migration Zooplankton migrate to avoid predators like fish which also increases their fitness. At night zooplankton spread out because night predation is more difficult for predators

The abundance of zooplankton in Johnson pond at noon

Temperate and oxygen levels of Johnson pond during the day and night Surface water was warmer during the day than bottom of the pond. At night water was the same temperature allowing the movement of zooplankton Oxygen levels where higher on the bottom during the day but at night oxygen levels were found to be higher near the surface. With increase temperatures zooplankton migration cycle would be altered allowing for opportunities for predation and lower the overall fitness of zooplankton.

Predation-comparing warmer/cold water lakes Ice cover- helps to reduce the predation on zooplankton by shortening the growing season of phytoplankton Canadian lakes have less predation then Danish lakes which have a warmer climate Increase temperature will allow a longer time for predation of zooplankton

What can we expect in Lake Champlain with an increase in predation? Increased predation would lead to a decrease in zooplankton abundance and biomass. Less grazing on phytoplankton and algal biomass should increase More turbid conditions and greening of lakes A decline in invertebrates and amphibians

Zooplankton community composition determined by two major factors Predation Resource limitation Energy moves in direction of arrow Source: Lake Champlain Basin Program 2008

Predation - What has a more significant impact on zooplankton? Predators Resource Availability How can this be determined? Manipulate predator populations AND food sources in an existing system

Case Study: Vanni 1987 Increased food availability Phytoplankton levels were raised by elevating available nutrients Addition of planktivorous bluegill sunfish Zooplankton populations measured Cladocerans Copepods Rotifers

Cladocerans Copepods Rotifers

Results Zooplankton density primarily driven by resource limitation Most species saw population rise as a result of elevated food levels, even with added predators Species composition significantly affected by predation All Cladoceran species reached larger mature body size in the absence of sunfish Average size Cladocerans initiated reproduction was smaller in the presence of predator species

Case Study: Elser & Carpenter 1988 Removal of Piscivorous largemouth bass Addition of planktivorous minnows Comparison between study lake (Tuesday) and reference lake (Paul) that naturally exhibits manipulated fish populations

Results Paul lake = dashed lines, Tuesday lake= solid line, vertical line = spring manipulation Source: Elser & Carpenter 1988

Results After Manipulation: Shift towards larger mean body size Before manipulation: larger zooplankton present at low levels Smaller sized species represent most of biomass After Manipulation: Shift towards larger mean body size Higher concentration of larger species than before

Invasive Predators Alosa pseudoharengus Dreissena polymorpha

Case Study: Beisner et al. 2003 Lake Champlain: Invasive Alewife is exploiting the Rainbow Smelt population Crystal and Sparkling Lake (WI): Invasive Rainbow Smelt is interfering with indigenous Alewife population Zooplankton data taken before and after the invasion was studied

Findings (D) = Daphnia, (CL) = non-daphnid cladocerans, (CAL) = Calanoid Copepods, (CYC) = Cyclopoid Copepods Source: Beisner et al. 2003

Zebra Mussels Solid line = Observed impacts, Dotted line = Potential impacts (+) = Taxa benefitting from zebra mussels, (-) = Taxa exhibiting adverse effects due to zebra mussels Source: MacIsaac 1996.

Possible Impacts on Zooplankton Reduction in zooplankton biomass Direct - ingestion of smaller taxa (copepod nauplii) May alter species composition Indirect - Filtration of suspended solids and phytoplankton could result in food limitation

Conclusions Large zooplankton populations are likely to decrease Reduce food sources for higher trophic levels Reduction of species dependent on large zooplankton Increase in species feeding on small taxa Significant changes in lake species composition!

Recommendations! Long term monitoring in Lake Champlain Efforts to decrease P loading Practice best management processes to reduce invasives and further disruption More $$ for research!!!

References Alain P, Hann D and B. Climate change, diapause termination and zooplankton population dynamics: an experimental and modeling approach. Freshwater Biology, 2009 54. p. 221–235 Beisner, B.E., Ives, A.R., Carpenter, S.R. The Effects of an Exotic Fish Invasion on the Prey Communities of Two Lakes. The Journal of Animal Ecology,2003. 72(2), 331-342.   Borer E T, Seabloom I, Shurin J B, Anderson K E, Blanchette C, Broitman B, Cooper SD, Harpen BS. What Determines the Strength of the Trophic Cascade? Ecology Society of America, 2005. 86.p. 528-537. Courture S C, Watzin M C. Diet of Invasive Adult White Perch (Monroe Americana) and their Effects on the Zooplankton Community in Missisquoi Bay, Lake Champlain. Journal of Great Lakes Res. 2008. 34. P. 485-494. Dale V H, Swartzman G L. Simulating the Effects of Increased Temperature in a Plankton Ecosystem: A Case Study; Algae as Ecological Indicators, Academic Press, New York; 1984. p 395-427, 13 fig, 4 tab, 44 ref. Contract No. NRC 04-75-222 Esler, J.J., & Carpenter S.R. Predation-Driven Dynamics of Zooplankton and Phytoplankton Communities in a Whole-Lake Experiment. Oecologia,1998 76(1), 148-154.

Genkai-Kato M, Carpenter S R Genkai-Kato M, Carpenter S R. Eutrophication Due to Phosphorus Recycling in Relation to Lake Morphometry, Temperature and Macrophytes. Ecological Society of America, 2005. 86. p. 210-219. Gyllstrom M, Hansson L A, Jeppesen E, Garcia-Cirado F, Gross E, Irvine K, Kairesalo T. The Role of Climate in Shaping Zooplankton Communities ofShallow Lakes. American Society of Limnology and Oceanography, 2005. 50. p. 2008-2021. Hampton S E, et al. Sixty years of environmental change in the world’s largest freshwater lake – Lake Baikal, Siberi. Global Change Biology, 2008. 14. P. 1947-1958.   Heyhoe K, et al. Past and future changes in climate and hydrological indicators in the US Northeast. Climate Dynamics, 2007. 28. P. 381-407. Jackson LJ. “A comparison of shallow Danish and Canadian lakes and implications of climate change” Freshwater Biology, 2007. 52. P. 1782-1792  Kirk K, Gilbert J J. Suspended Clay and the Population Dynamics of Population Dynamics of Planktonic Rotifers and Cladocerans. Ecology, 1990. 71(5). p. 1741-1755 MacIsaac, H.J., (1996). Abiotic and Biotic Impacts of Zebra Mussels on the Inland Waters of North America. American Zoologist, 36 (3), 287-299. Meng Zhou, Mark E. Huntley dynamics theory of plankton based on biomass spectra. Marine Ecology Progress Series, 1997. 159. p. 61-73 Molinero JC. Climate control on the long-term anomalous changes of zooplankton communities in the Northwestern Mediterranean. Global Change Biology, 2008. 14 .p. 11-26 Schmitz O J, Post E, Burns C E, Johnston K M. Ecosystem Responses to Global Climate Change: Moving Beyond Color Mapping. BioScience, 2003. 12. p. 1999-1205 Norbert J, DeAngelis D. Temperature effects on stocks and stability of a phytoplankton-zooplankton model and the dependence on light and nutrient. Ecological Modeling, 1997. 95 (1). P. 75-86. Sweetman J N, LaFace E, Riihland K M, Smol J P. Evaluating the Response of Cladocera to Recent Environmental Changes in Lakes from the Central Canadian Arctic Treeline Region Arctic, Antarctic, and Alpine Research, 2008. 40(3)p. 584-591 Vanni M.J. Effects of Food Availability and Fish Predation on a Zooplankton Community. Ecological Monographs, 1987. 57(1), 61-88. Verburg P, Hecky R E, Kling H. Ecological Consequences of a Century of Warming in Lake Tanganyika. Science, 2003. 301(5632) p. 505 – 507.