Identifying Potential Zebra Mussel Colonization 385 Identifying Potential Zebra Mussel Colonization David e stier Marc Alan Leisenring Matthew glen Kenned Humboldt State University Arcata. ca 95221 Advisor: Eileen m. cashman Summary Both environmental and anthropogenic factors influence the spread of zebra mussels to new areas. Variations in water quality can affect both proliferation and mortality, which greatly influence colonization rate. High levels of calcium and alkalinity in fresh waters tend to increase juvenile zebra mussel population Dreissena also requires specific ranges of pH, temperature, and potassium con- centration for propagation. Consumption by predators and spread by humans also influence colonization and population dynamics We develop a lumped-parameter stochastic model using data from a lake with known water quality, using optimal water quality parameter ranges for zebra mussel survival. The model predicts the susceptibility to colonization of a lake with known water quality. We find a significant probability for seasonal colonization in Lake B but gligible probability for Lake C The use of de-icing agents in the vicinity of Lake B may increase the proba bility of colonization, due to elevated calcium concentrations in the lake Literature review ry The zebra mussel originated in the Caspian and Black Sea regions. By the early 19th century, a well-developed population was established throughout The UMAP Journal 22 (4)(2001)385-397. Copyright 2001 by COMAP, Inc. Allrights reserved Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial dvantage and that copies bear this notice. Abstracting with credit is permitted, but copyrights for components of this work owned by others than COMAP must be honored. To copy otherwise to republish, to post on servers, or to redistribute to lists requires prior permission from COMAP
Identifying Potential Zebra Mussel Colonization 385 Identifying Potential Zebra Mussel Colonization David E. Stier Marc Alan Leisenring Matthew Glen Kennedy Humboldt State University Arcata, CA 95221 Advisor: Eileen M. Cashman Summary Both environmental and anthropogenic factors influence the spread of zebra mussels to new areas. Variations in water quality can affect both proliferation and mortality, which greatly influence colonization rate. High levels of calcium and alkalinity in fresh waters tend to increase juvenile zebra mussel population. Dreissena also requires specific ranges of pH, temperature, and potassium concentration for propagation. Consumption by predators and spread by humans also influence colonization and population dynamics. We develop a lumped-parameter stochastic model using data from a lake with known water quality, using optimal water quality parameter ranges for zebra mussel survival. The model predicts the susceptibility to colonization of a lake with known water quality. We find a significant probability for seasonal colonization in Lake B but negligible probability for Lake C. The use of de-icing agents in the vicinity of Lake B may increase the probability of colonization, due to elevated calcium concentrations in the lake. Literature Review History The zebra mussel originated in the Caspian and Black Sea regions. By the early 19th century, a well-developed population was established throughout The UMAP Journal 22 (4) (2001) 385–397. c Copyright 2001 by COMAP, Inc. All rights reserved. Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice. Abstracting with credit is permitted, but copyrights for components of this work owned by others than COMAP must be honored. To copy otherwise, to republish, to post on servers, or to redistribute to lists requires prior permission from COMAP
386 The UMAP Journal 22. 4(2001) the major drainages of Europe in connection with extensive canal building lUSGS 2001. Researchers surmise that the zebra mussel first arrived in north America in the mid-1980s in a ballast tank of a commercial vessel the first recorded population appeared in Lake St Clair, Canada [herbert et al. 1989 By 1990, the zebra mussel habitat encompassed the great lakes and soon after entered the Mississippi River drainage via the Illinois River. Today, zebra mussels exist in at least 21 states [ USGs 2001] Factors Influencing Propagation Physical Mechanism of Propagation Anthropogenic activities are considered the most influential factor in spread ing zebra mussels [Mackie and Schloessler 1996]. Zebra mussels attach them selves to firm surfaces including boat hulls, nets, buoys, and floating debris Balcom and rohmer 1994; Ram and mcmahon 1996. a zebra mussel dis lodged in transport can start a new population Natural dispersion mechanisms include birds, water currents, insects, and other animals [mackie and schloesser 1996; Hincks and Mackie 1997 . When carried by currents, microscopic zebra mussel larvae, called veligers, can quickly disperse themselves [Mackie and Schloesser 1996]. The mussels can travel large distances in the two-to three-week free-swimming veliger stage [Rice 1995] The species has demonstrated resilience to long-overland trips. Zebra mus sels survive longest under cool, moist conditions, similar to the environment in a boat hull Payne 1992] Habitat Zebra mussel habitat includes freshwater lakes and reservoirs as well as cooling ponds, quarries, and irrigation ponds of golf courses. However, the species can survive where salinity does not exceed 8 to 12 parts per thousand (ppt)[Mackie and schloesser 1996] sea abra mussels prefer hard substrates[Heath 1993] but can survive on soft sediment [Stoeckel et al. 1997 ]. Current velocities up to 2 m/s provide opti mal settlement conditions, while speeds ranging from 0.5 m/s to 1.5 m/s best support growth [Rice 1995] Water Quality H Zebra mussels have colonized areas with pH values ranging from 7.0 to 9.0. A pH of 7.5 promotes optimum growth [ Rice 1995 Potassium The optimal range of potassium in the environment is 0.5-1.5 mg/L, with survival at 2-3 mg/L [Dietz et al. 1996 Calcium and Alkalinity Calcium and alkalinity are the strongest infuences on zebra mussel growth and reproduction [Heath 1993]. Zebra mussels require
386 The UMAP Journal 22.4 (2001) the major drainages of Europe in connection with extensive canal building [USGS 2001]. Researchers surmise that the zebra mussel first arrived in North America in the mid-1980s in a ballast tank of a commercial vessel; the first recorded population appeared in Lake St. Clair, Canada [Herbert et al. 1989]. By 1990, the zebra mussel habitat encompassed the Great Lakes and soon after entered the Mississippi River drainage via the Illinois River. Today, zebra mussels exist in at least 21 states [USGS 2001]. Factors Influencing Propagation Physical Mechanism of Propagation Anthropogenic activities are considered the most influential factor in spreading zebra mussels [Mackie and Schloessler 1996]. Zebra mussels attach themselves to firm surfaces including boat hulls, nets, buoys, and floating debris [Balcom and Rohmer 1994; Ram and McMahon 1996]. A zebra mussel dislodged in transport can start a new population. Natural dispersion mechanisms include birds, water currents, insects, and other animals [Mackie and Schloesser 1996; Hincks and Mackie 1997]. When carried by currents, microscopic zebra mussel larvae, called veligers, can quickly disperse themselves [Mackie and Schloesser 1996]. The mussels can travel large distances in the two- to three-week free-swimming veliger stage [Rice 1995]. The species has demonstrated resilience to long-overland trips. Zebra mussels survive longest under cool, moist conditions, similar to the environment in a boat hull [Payne 1992]. Habitat Zebra mussel habitat includes freshwater lakes and reservoirs, as well as cooling ponds, quarries, and irrigation ponds of golf courses. However, the species can survive where salinity does not exceed 8 to 12 parts per thousand (ppt) [Mackie and Schloesser 1996]. Zebra mussels prefer hard substrates [Heath 1993] but can survive on soft sediment [Stoeckel et al. 1997]. Current velocities up to 2 m/s provide optimal settlement conditions, while speeds ranging from 0.5 m/s to 1.5 m/s best support growth [Rice 1995]. Water Quality pH Zebra mussels have colonized areas with pH values ranging from 7.0 to 9.0. A pH of 7.5 promotes optimum growth [Rice 1995]. Potassium The optimal range of potassium in the environment is 0.5–1.5 mg/L, with survival at 2–3 mg/L [Dietz et al. 1996]. Calcium and Alkalinity Calcium and alkalinity are the strongest influences on zebra mussel growth and reproduction [Heath 1993]. Zebra mussels require
Identifying Potential Zebra Mussel Colonization 387 a Ca* concentration of 12 mg/l and CaCO3 concentration of 50 mg/I[Heath 1993]. Ramcharan et al. [1992] found that European lakes with pH below 7.3 and Ca+2 concentration below 28. 3 mg/l lacked zebra mussels, but in North America there are numerous examples ofinvasion at far lower calcium concentrations Dissolved Oxygen Heath [1993] indicates a minimum oxygen threshold of 25% oxygen saturation, or 2 mg/I at 25C. Dense overgrowths of zebra mussels may deplete dissolved oxygen enough to cause large die-offs of Dreissena and other aquatic species [Ramcharan et al. 1992 Nutrients and Phytoplankton A water body s chlorophyll-a concentration is a factorin growth variability of the zebra mussel [Mackie and Schloesser 1996 Zebra mussels compete with herbivorous zooplankton and fish for phyto- plankton [Ramcharan et al. 1992]. Zebra mussels collect their food through ciliary filter feeding processes [McMahon 1996 that filtering increases water clarity, and light penetration fosters growth in the lake's benthic population [Maclsaac 1996], which can increase the nuisance aquatic weed biomass Salinity Research suggests optimal salinity for adults is 1 ppt at high temper atures(18-20 C)and 2-4 ppt in lower temperatures(3-12 C)Kilgour et al 1994; Mackie and Schloesser 1996]. Rice [1995] suggests 1 ppt as optimal for growth and short-term tolerance of 12 ppt; but zebra mussels have high adaptive ability to nonideal conditions in salinity and other water quality parameters. Temperature For reproduction, the zebra mussel requires prolonged periods above 12C and maximum temperatures ranging from 18 to 23C [Heath 1993: McMahon 1996]. It cant survive in temperatures greater than 32 C, the lower temperature survival threshold is 0oC [Heath 1993 Predators Crustacean zooplankton and larval fish consume the larval stages of the mussel [Mackie and Schloesser 1996]. Adult Dreissena provide food for crayfish, fish, and waterfowl [Mackie and Schloessler 1996]. Fish ob- served consuming zebra mussels include yellow perch, white perch, wall- eye,white bass, lake whitefish, lake sturgeon, and the round goby [Maclsaac 1996: French 1993. Potential consumers include the freshwater drum, re dear sunfish, pumpkinseed, copper and river redhorse, and common carp Round gobies consume 50-100 zebra mussels per day, depending on the size of the mollusk [Ghedottiet al. 1995. Diving waterfowl consume significant amounts of zebra mussels in proper conditions. Hamilton et al. [1994] found the ducks devoured 57% of the autumn mussel biomass in lake erie: but due to icing over of the lake and consequent lack of winter predation, continued juvenile growth diminished the effects of the consumption
Identifying Potential Zebra Mussel Colonization 387 a Ca+2 concentration of 12 mg/l and CaCO3 concentration of 50 mg/l [Heath 1993]. Ramcharan et al. [1992] found that European lakes with pH below 7.3 and Ca+2 concentration below 28.3 mg/l lacked zebra mussels, but in North America there are numerous examples of invasion at far lower calcium concentrations. Dissolved Oxygen Heath [1993] indicates a minimum oxygen threshold of 25% oxygen saturation, or 2 mg/l at 25◦C. Dense overgrowths of zebra mussels may deplete dissolved oxygen enough to cause large die-offs of Dreissena and other aquatic species [Ramcharan et al. 1992]. Nutrients and Phytoplankton A water body’s chlorophyll-a concentration is a factor in growth variability of the zebra mussel [Mackie and Schloesser 1996]. Zebra mussels compete with herbivorous zooplankton and fish for phytoplankton [Ramcharan et al. 1992]. Zebra mussels collect their food through ciliary filter feeding processes [McMahon 1996]; that filtering increases water clarity, and light penetration fosters growth in the lake’s benthic population [MacIsaac 1996], which can increase the nuisance aquatic weed biomass. Salinity Research suggests optimal salinity for adults is 1 ppt at high temperatures (18–20◦C) and 2–4 ppt in lower temperatures (3–12◦C) [Kilgour et al. 1994; Mackie and Schloesser 1996]. Rice [1995] suggests 1 ppt as optimal for growth and short-term tolerance of 12 ppt; but zebra mussels have high adaptive ability to nonideal conditions in salinity and other water quality parameters. Temperature For reproduction, the zebra mussel requires prolonged periods above 12◦C and maximum temperatures ranging from 18 to 23◦C [Heath 1993; McMahon 1996]. It can’t survive in temperatures greater than 32◦C; the lower temperature survival threshold is 0◦C [Heath 1993]. Predators Crustacean zooplankton and larval fish consume the larval stages of the mussel [Mackie and Schloesser 1996]. Adult Dreissena provide food for crayfish, fish, and waterfowl [Mackie and Schloessler 1996]. Fish observed consuming zebra mussels include yellow perch, white perch, walleye, white bass, lake whitefish, lake sturgeon, and the round goby [MacIsaac 1996; French 1993]. Potential consumers include the freshwater drum, redear sunfish, pumpkinseed, copper and river redhorse, and common carp. Round gobies consume 50–100 zebra mussels per day, depending on the size of the mollusk [Ghedotti et al. 1995]. Diving waterfowl consume significant amounts of zebra mussels in proper conditions. Hamilton et al. [1994] found the ducks devoured 57% of the autumn mussel biomass in Lake Erie; but due to icing over of the lake and consequent lack of winter predation, continued juvenile growth diminished the effects of the consumption
388 The UMAP Journal 22. 4(2001) Modeling Zebra mussels Zebra mussel populations demonstrate high sensitivity to small changes in water quality parameters. In some lakes, the long-term population size remains fairly constant, while populations in other lakes fluctuate greatly from year to yea Modeling History Some of the more common types of models developed include multivariate, bioenergetic, and probabilistic . Multivariate models have been used to determine the environmental factors that most influence the ability of Dreissena to establish viable populations IRamcharan et al 19921 Bioenergetic models focused on modeling individual zebra mussel growth as a function of certain environmental factors [ Schneider 1992 Probabilistic models used discrete probabilities associated with environmen- tal variables known to contribute to the successful colonization of freshwater bodies to evaluate the susceptibility of certain lakes to zebra mussel colo nization [Miller and ignacio 1994 Model Development Model Choice and approach We develop an analytical model that is transient, lumped-parameter, and stochastic We obtained from the literature ranges of water quality the parameters that are necessary for survival. Using a time step of one year, we determine the probability of survival based on those and determine the population. We use the data on Lake a to calibrate and verify the model's ability to predict colonization Data Considerations The data files provided contain water quality and population data for Lake a Shared by most files were calcium concentration(mg/L), chlorophyll concen tration(ug/L), potassium concentration(mg/L), temperature(C), and pH, all of which the literature shows are important factors We use the average juvenile population for a given year for comparison with the model results, regardless of the amount of data available for that year. Therefore, for each time step, we need an annual average and standard deviation for each parameter and each population. We assume that the average value is the average for the year
388 The UMAP Journal 22.4 (2001) Modeling Zebra Mussels Zebra mussel populations demonstrate high sensitivity to small changes in water quality parameters. In some lakes, the long-term population size remains fairly constant, while populations in other lakes fluctuate greatly from year to year. Modeling History Some of the more common types of models developed include multivariate, bioenergetic, and probabilistic: • Multivariate models have been used to determine the environmental factors that most influence the ability of Dreissena to establish viable populations [Ramcharan et al. 1992]. • Bioenergetic models focused on modeling individual zebra mussel growth as a function of certain environmental factors [Schneider 1992]. • Probabilistic models used discrete probabilities associated with environmental variables known to contribute to the successful colonization of freshwater bodies to evaluate the susceptibility of certain lakes to zebra mussel colonization [Miller and Ignacio 1994]. Model Development Model Choice and Approach We develop an analytical model that is transient, lumped-parameter, and stochastic. We obtained from the literature ranges of water quality the parameters that are necessary for survival. Using a time step of one year, we determine the probability of survival based on those and determine the population. We use the data on Lake A to calibrate and verify the model’s ability to predict colonization. Data Considerations The datafiles provided contain water quality and population data for Lake A. Shared by most files were calcium concentration (mg/L), chlorophyll concentration (µg/L), potassium concentration (mg/L), temperature (◦C), and pH, all of which the literature shows are important factors. We use the average juvenile population for a given year for comparison with the model results, regardless of the amount of data available for that year. Therefore, for each time step, we need an annual average and standard deviation for each parameter and each population. We assume that the average value is the average for the year
Identifying Potential Zebra Mussel Colonization 389 Review of literature Calcium, alkalinity, phytoplankton, potassium, water temperature, and ph are important for survival. Because of the dependence between alkalinity and calcium concentration, we use only calcium. We use chlorophyll-a in place of phytoplankton to represent available food. We summarize in Table 1 the ranges of water quality parameters required for survival Optimal water quality conditions for survival of each age class. Constituents Age Group Ca(mg/L) Chl-a(ug/L) K(mg/L) Temp LL UL LL UL LL UL LL UL LL UL Birth 50+ 1234 0038 0051.2778.51221 0051.2778.51221 00051.37387528 300051.5529.3031 10 0051.5529.3031 Methodology The model uses assumptions about probabilities of survival at specific age classes Age Classes We divide zebra mussels into four distinct age classes: class 1(0-l years) class 2(1-2 years), class 3(2-3 years), and class 4(3-4 years). At the end of each time step( one year), the population of each age class moves into the next age class, except that class 4 dies. Values for each water quality parameter are specified at each time step Survival Probabilities The ranges of values for each parameter are divided into smaller rang and assigned survival probabilities. A normal distribution is used to create a probability distribution for each parameter. For each age class, we take the mean of the optimal range found in the literature. Newborns and age class 1 use the same ranges and probabilities: classes 3 and 4 also use their own same ranges and probabilities; age class 2 has its own ranges and probabilities. A normal distribution is fit to the average; we assume that the limits of the optimal ranges in the literature represent one standard deviation from the mean
Identifying Potential Zebra Mussel Colonization 389 Review of Literature Calcium, alkalinity, phytoplankton, potassium, water temperature, and pH are important for survival. Because of the dependence between alkalinity and calcium concentration, we use only calcium. We use chlorophyll-a in place of phytoplankton to represent available food. We summarize in Table 1 the ranges of water quality parameters required for survival. Table 1. Optimal water quality conditions for survival of each age class. Constituents Age Group Ca (mg/L) Chl-a (µg/L) K (mg/L) pH Temp LL UL LL UL LL UL LL UL LL UL Birth 20 50+ 0 15 0.05 1.2 7.7 8.5 12 21 1 20 50+ 0 15 0.05 1.2 7.7 8.5 12 21 2 15 50+ 3 20 0.05 1.3 7.3 8.7 5 28 3 10 50+ 8 30 0.05 1.5 5.2 9.3 0 31 4 10 50+ 8 30 0.05 1.5 5.2 9.3 0 31 Methodology The model uses assumptions about probabilities of survival at specific age classes. Age Classes We divide zebra mussels into four distinct age classes: class 1 (0–1 years), class 2 (1–2 years), class 3 (2–3 years), and class 4 (3–4 years). At the end of each time step (= one year), the population of each age class moves into the next age class, except that class 4 dies. Values for each water quality parameter are specified at each time step. Survival Probabilities The ranges of values for each parameter are divided into smaller ranges and assigned survival probabilities. A normal distribution is used to create a probability distribution for each parameter. For each age class, we take the mean of the optimal range found in the literature. Newborns and age class 1 use the same ranges and probabilities; classes 3 and 4 also use their own same ranges and probabilities; age class 2 has its own ranges and probabilities. A normal distribution is fit to the average; we assume that the limits of the optimal ranges in the literature represent one standard deviation from the mean