BIOCONTROL OF EURASIAN WATER -MILFOIL IN CENTRAL NEW YORK STATE: Myriophyllum spicatum L., ITS INSECT HERBIVORES AND ASSOCIATED FISH

Paul H. Lord

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BIOLOGICAL FIELD STATION COOPERSTOWN, NEW YORK

Occasional Paper No. 38 August 2004

STATE UNIVERSITY COLLEGE AT ONEONTA 3

ABSTRACT The recreationally impeding, exotic aquatic macrophyte Myriophyllum spicatum (Eurasian water-milfoil) has been the target of control attempts in North America using physical, chemical, and biological methods. Much recent focus has been on the use of the latter, particularly the use of herbivorous insects. This work describes an attempt to augment existing populations of an M. spicatum herbivore considered)o have M. spicatum control potential in the Northeast U.S., Acentria ephemerella, an aquatic macrophyte moth, and follow-up work monitoring insect herbivores of M. spicatum, plant community structure, and fish community structure in nine central New York State lakes. Results show poor recruitment ofA. ephemerella after emergence of the initially introduced larvae with no significant control ofM. spicatum. Fish predation on A. ephemerella was suspected to be responsible, leading to another season's work contrasting populations offish, M. spicatum, and M. spicatum herbivores found in Otsego Lake, a lake with controlled M. spicatum, with those same communities found in theA. ephemerella augmentation site, Lebanon Reservoir. Lepomis macrochirus (bluegill) was identified as the most likely controlling predator on M. spicatum herbivores. A final season's work contrasted those same communities in eight Madison County lakes with varying degrees of dominance by M. spicatum. Results indicate that L. macrochirus and L. gibbosus (pumpkinseed) are effective controls on A. ephemerella while substantial Sander vitreus (walleye) populations may limit Lepomis spp. populations pennitting M. spicatum insect herbivore densities to expand. 4

CONTENTS

ACKNOWLEDGEMENTS 2 ABSTRACT 3 TABLE OF CONTENTS .4 LIST OF TABLES 5 LIST OF FIGURES 6 INTRODUCTION 8 BACKGROUND 8 Myriophyllum spicatum and control methodologies 8 Aquatic Macrophyte Moth: Acentria ephemerella (Lepidoptera: Pyralidae) 12 Milfoil Weevil: Euhrychiopsis lecontei (Coleoptera:Curculionidae) 13 Milfoil Midge: Cricotopus myriophylli (Diptera:Chironomidae) 14 Herbivory Potential. 15 Fish Predation 15 2001 STUDY: LEBANON RESERVOIR AUGMENTATION 16 2001 STUDY BACKGROUND 16 2001 STUDY HyPOTHESIS 18 2001 STUDY METHODOLOGy...... 18 2001 STUDY RESULTS 23 2001 STUDY DISCUSSION OF RESULTS 28 2002 STUDY: COMPARISON OF TWO LAKES 28 2002 STUDY BACKGROUND 28 2002 STUDY METHODOLOGy 29 2002 STUDY RESULTS 33 2002 STUDY DISCUSSION OF RESULTS 36 2003 STUDY: COMPARISON OF EIGHT LAKES 39 2003 STUDY BACKGROUND 39 2003 STUDY METHODOLOGy 39 2003 STUDY RESULTS 40 2003 STUDY DISCUSSION OF RESULTS 44 RECOMMENDATIONS FOR FUTURE RESEARCH .49 REFERENCES 50 APPENDIX A: Identification of herbivory on Myriophyllum spicatum, Eurasian water-milfoil, stem samples 67 5

CONTENTS (CONTINUED)

LIST OF TABLES Table 1. 2001 Lebanon Reservoir site and plot location data. 20

Table 2. Counts and calculations used to estimate numbers ofAcentria 24 ephemerella larvae and pupae transferred into Lebanon Reservoir on 31 May and evaluated on 1 June 2001.

Table 3. Counts and calculations used to estimate numbers ofAcentria 24 ephemerella larvae and pupae transferred into Lebanon Reservoir as of8 June and evaluated on 11 June 2001.

Table 4. Counts and calculations used to estimate numbers ofAcentria 25 ephemerella larvae and pupae transferred into Lebanon Reservoir as of 14 June and evaluated onI5 June 2001.

Table 5. Counts and calculations used to estimate numbers of 25 surviving augmented Acentria ephemerella larvae and pupae in Lebanon Reservoir.

Table 6. Lebanon Reservoir Acentria ephemerella larvae per stem 26 calculations.

Table 7. Otsego Lake electrofishing catch rates (catch / hour) for game 35 and non-game fish for June 2000, October 2001, June 2002 and October of2002 (modified from Cornwell [2003]).

Table 8. Lebanon Reservoir electrofishing catch rates for game and 35 non-game fish for July 2002.

Table 9. Statistically significant regression equations defining the trophic 41 relationships between Lepomis macrochirus and L. gibbosus, Acentria ephemerella, and Myriophyllum spicatum as calculated from 2003 Madison County lakes data.

Table 10. Regression equations for Myriophyllum spicatum stems at 3 m 42 and M. spicatum percent oftotal biomass at 3 m, average M. spicatum stem length at 3 m, M. spicatum biomass weight at 3m, and all plants biomass weight at 3 m.

Table 11. Myriophyllum spicatum percent ofbiomass at 3 m and notes 42 regarding fish contrasted for eight Madison County, NY lakes in 2003. 6

CONTENTS (CONTINUED)

Table 12. Principal results of May - June 2003 monitoring in eight 43 Madison County, NY lakes.

Table 13. Sander vitreus stockings in Eaton Brook Reservoir 46 1993 ­ 2003.

Table 14. Sander vitreus stockings in Tuscarora Reservoir 1993 - 2003. 47

Table 15. New York State Department of Environmental Conservation 47 stocking rate for June Sander vitreus fingerlings compared to the stocked rates for each of the four Madison County S. vitreus lakes.

LIST OF FIGURES

Figure 1. Graph from Hairston et at. (2000) illustrating inverse 16 relationship found in fish numbers and Myriophyllum spicatum herbivore numbers in Cornell University Research Ponds.

Figure 2. Lebanon Reservoir (from DeLorme 3-D TopoQuads® 19 New York) annotated with Sites 1,2, & 3, Plots A - F and water quality (WQ) evaluation point.

Figure 3. Acentria ephemerella augmentation bundle design and jars 21 used for transport ofbundles.

Figure 4. Low impact aquatic macrophyte sampler rake designed and 22 built for 2001 research compared with a standard 30.6 cm measuring stick.

Figure 5. Acentria ephemerella larvae per stem sampled on ten different 27 2001 dates in Lebanon Reservoir control plots.

Figure 6. Acentria ephemerella larvae per stem sampled on ten different 27 2001 dates in Lebanon Reservoir augmented plots.

Figure 7. Otsego Lake grid pattern for 2002 aquatic macrophyte and 31 herbivore sampling.

Figure 8. Lebanon Reservoir grid pattern for 2002 aquatic macrophyte 32 and herbivore sampling. 7

CONTENTS (CONTINUED)

Figure 9. Results of2002 research comparing Lebanon 33 Reservoir and Otsego Lake Myriophyllum spicatum, M spicatum herbivores, and fish.

Figure 10. Hypothetical model illustrating understood trophic 38 relationships between Lepomis macrochirus, Myriophyllum spicatum herbivores, and M. spicatum as perceived from Otsego Lake and Lebanon Reservoir data.

Figure 11. Confirmed model (refinement ofFigure 9) illustrating 44 statistically significant trophic relationships between Lepomis macrochirus and L. gibbosus and the Acentria ephemerella, and M)wiophyllum spicatum as calculated from 2003 Madison County lakes data.

Figure 12. Hypothetical model illustrating understood trophic 48 relationships between Sander vitreus, L. macrochirus and L. gibbosus, milfoil insect herbivores, and Myriophyllum spicatum as perceived from Madison County 2003 lakes data. 8

INTRODUCTION

The question central to the four plus years of research reported upon here is: Why does Myriophyllum spicatum (Eurasian water-milfoil; Haloragales: Haloragaceae) cause such problems in the U.S. when it is noted to be relatively sparsely present (Center, 1981, Lambert-Servien, 1998) and rarely a problem (Smith, 1982) in its native range? Is it because of the relative paucity ofAcentria ephemerella (the aquatic macrophyte moth) found in the U.S. (Hairston, et al., 2000; this study) when compared with that same species populations in Europe (Gross and Kornijow, 2002; Gross et al., 2002)?

BACKGROUND

Myriophyllum spicatum and control methodologies

Myriophyllum spicatum is an exotic species believed to have been introduced into North American waters sometime in the early l880s near the Chesapeake Bay (Reed, 1977), although Couch and Nelson (1985) make a good case that it may not have actually been introduced until the early 1940s. Aiken et al. (1979) authoritatively describes it. Myriophyllum spicatum is difficult to distinguish from congeners native to North America (Aiken et al., 1979; Aiken, 1981; Center, 1981, Gerber & Les, 1994) as noted by a review of Crow and Hellquist (2000), which differentiates members of the genus by flower parts. This is unfortunate since, in many Northeastern U.S. lakes, Myriophyllum spp. flowers are evident for short periods, if at all (personal observation). Compounding the identification challenge, M. spicatum can hybridize with native milfoils (Moody & Les, 2003; Thurn, 2003). Species identification of M. spicatum, when not in flower, is based on the relative flaccidity and number of the dissected veins that form the leaves, the acuteness of the leaf, and the depth at which the plant flourishes. Myriophyllum spicatum typically has more than 11 dissected veins on each side of the leaf (Crow & Hellquist, 2000), however, care needs to be exercised in using this guideline since M. spicatum can have between 5 and 25 vein pairs (Aiken, et at. 1979). Unlike local native water­ milfoils, these dissected veins appear flacid and lay against the stem when the plant is removed from the water (Johnson, 2000). Additionally, M. spicatum branches copiously as its stem approaches the water's surface, while natives rarely branch in water greater than 1m deep. Finally, native water-milfoils overwinter as turions, which are evident in late autumn, winter, and early spring, while M. spicatum persists as a perennial evergreen herb (Aiken et al., 1979; Grace & Wetzel, 1978).

Myriophyllum spicatum lives under the ice, growing when light is available (under clear ice), and dying back slowly toward its stolon (under snow covered ice) when light is not available (personal observation; Aiken et al., 1979). When the ice melts, stolons (horizontal stems from the plant base that produce new vertical stems) sprout new stems and persisting stems grow quickly buoyed by stored CO2, dominating native plants that need warmer water for early season growth (Titus & Adams, 1979a; Creed & Sheldon, 1994; personal observation). If M. spicatum 9 reaches the water's surface without interference, it quickly forms dense canopies shading out most other aquatic plants beneath it and the lower leaves on its own stem which slough off (Grace & Wetzel, 1978; Titus & Adams, 1979a; Aiken et al., 1979; personal observation). Flowers are sometimes formed, typically in July or August in the Northeastern u.s. Seed production may follow. Reproduction, however, is almost always asexual, by expansion of stolons and by fragmentation (Aiken et al., 1979, Madsen, 1993; Madsen 1998).

A variety of authors (Grace & Wetzel, 1979; Aiken et al., 1979, Titus & Adams, 1979b; Smith & Barko, 1990; Madsen, 1993) describe abscission or autofragmentation in M. spicatum. However, it may be that healthy M. spicatum does not fragment itself; rather, long stems, particularly ones which form canopies, are subject to twisting, weakening or breakage. Weakened stems interrupt the flow of nutrients from roots to meristems. This can occur by wind or by animal or human entanglement or by the actions of herbivores feeding on M. spicatum. Regardless of how M. spicatum is fragmented, roots quickly develop on pieces not well connected to lower stem and roots. A change in buoyancy accompanies this development. Stem fragments without roots are positively buoyant (Grace & Wetzel, 1978), and, as a consequence, gain better access to light, while rooted fragments become negatively buoyant (Grace & Wetzel, 1978), affording better access to substrates. Myriophyllum spicatum obtains two frequently limiting nutrients, phosphorus and nitrates, from the substrate (Best & Mantai, 1978; Painter & McCabe, 1988; Lillie & Barko, 1990; Brade & Mantai, 1991) although it obtains ammonium from the water (Wetzel, 1983; Walstad, 1999).

Myriophyllum spicatum is now found throughout North America where it inhabits a wide variety of lakes, but is found most densely in mesotrophic and moderately eutrophic lakes (Smith & Barko, 1990; Madsen, 1998). When abundant, M. spicatum impedes boating, water-skiing, fishing, and swimming, by forming a thick surface canopy (Smith & Barko, 1990). Development of protocols using insect herbivores to control this noxious, exotic aquatic macrophyte has been noted to be a worthwhile objective by various researchers (Batra, 1977; Buckingham & Ross, 1981; Kangasniemi, 1983; Oliver, 1984; Painter & McCabe, 1988; Macrae et al., 1990; Creed et al., 1992; Creed & Sheldon, 1994; Sheldon & Creed, 1995; Perry & Penner, 1996; Newman et al., 1997; Johnson et al., 1998; Cofrancesco & Crosson, 1999; Newman et al., 2002; Johnson & Blossey; 2002, Tamayo, 2003). However, other methods of control have also been used.

Physical methods of elimination were first used to control M. spicatum (Cofrancesco, 1998) and they remain in use today. Mechanical harvesting has been used widely with some unanticipated results. Ifnot cut repeatedly over the course of a season, M. spicatum regrows in greater density after cutting. Insects inhabiting the upper portions of the plants (including M. spicatum herbivores) are killed. As many as 25% of the fish, largely young-of-the-year, are killed in harvested areas and game fish habits change (Nichols & Cottam, 1972; Engle, 1990; Valley & Bremigan, 2002a,b). Hand pulling and substrate barriers have been successfully employed in 10 some North American lakes to keep nascent M. spicatum infestations from developing further. The key to satisfactory employment of these techniques appears to be early detection and action (LaMere, 1999; Smagula, 2002). Winter drawdown of water levels in lakes with controllable water levels has been widely used to freeze and kill M. spicatum in shallow areas. A properly timed drawdown and winter reflooding can remove organic sediment from the littoral zone increasing the average size of particles in the substrate and reducing M. spicatum densities for subsequent growing seasons (Lyman, 2001). However, such drawdowns may also make significantly more phosphorus available for algae and surviving macrophytes (Klotz & Linn, 2001), while killing nontarget organisms (e.g., invertebrate animals).

Inorganic chemical control approaches to aquatic macrophyte control were attempted shortly after physical methods were explored. In the 1940s, complex synthetic carbon compounds were first used (Cofrancesco, 1998). Four chemicals are currently used in the U.S. to target M. spicatum that permit some portion of the native plant community to persist.

Triclopyr (3,5,6-trich10ro-2-pyridinyloxyacetic acid combined with triethylamine salt [C 7H4CbN03J) is the most recently approved for use (Poovey et at., 2000; SePRO, 2003a; Mongin, 2003), although it is still not authorized for use in New York State (Kishbaugh, 2003). Triclopyr is sold as Renovate®, Garlon 3A®, Access®, Crossbow®, ET®, Grazon®, PathFinder®, Redeem®, Rely®, Remedy®, and Turflon®(Vermont Department of Environmental Conservation, 1993; Humberg et at., 1989). It is a systemic selective herbicide which kills plants by mimicking a plant hormone (auxin) causing unsustainable growth (SePRO, 2003a).

2,4-D (2,4-diclorophenoxy acetic acid [CgH6Ch03J) use against and impact on M. spicatum is described by Aiken et at. (1979) and Gangstad (1982). 2,4-D is the longest used "selective" aquatic herbicide. It is still widely used and is marketed as Aqua-Kleen®, Weedar®, and Landmaster®(Hoyer & Canfield, 1998; Vermont Department of Environmental Conservation, 1993; Gallager, 1992; Humberg et at., 1989). 2,4-D is a pseudo plant hormone (auxin) that resists counteraction by its controlling hormone (IAA oxidase) forming proteins that block plant stem flows and prevent energy storage (Levitt, 1969). It is somewhat selective for M. spicatum (Vermont Department of Environmental Conservation, 1996).

Fluridone (1-methyl-3-phenyl-5(3-(trifluromethyl) phenyl)-4(l H)-pyridinone [C19H14F3NOJ) is marketed as Sonar® by SePRO ®and as Avast!TM by Griffin L.L.C.® (SePRO Corporation®, 2003b; Griffin L.L.C.®, 2003). It is the most aggressively marketed "selective" aquatic herbicide. It acts by interfering with carotenoid production causing plants to die from sunlight that breaks up chlorophyll molecules throughout the plant. Its impact is long-lasting and any product not absorbed by plants is broken down by light and microbial action (Hoyer & Canfield, 1998; Vermont Department of Environmental Conservation, 1996; SePRO Corporation®, 2003b; Griffin L.L.c.®, 2003). This product has been used 11 successfully, twice, in the south basin of Lake Moraine, Madison County since 1996 (Hannan & Albright, 1997, Hannan, et al., 1998, 2000a, 2001 a, 2002, in prep).

Endothall (3,6-endoxohexahydrophthalic acid [CgHIOOSJ) is available as a disodium compound and as an amine salt of endothall. It is sold as Accelerate®, Des­ i-cate®, Aquathol®, and Hydrothol®by Elf Atochem® North America, Inc (Hoyer & Canfield, 1998; Elf Atochem® North America, Inc, 1996; Humberg et al., 1989). It works as a contact herbicide that is somewhat selective for M. spicatum (Netherland, 1991; Oregon State University, 1998; Vennont Department of Environmental Conservation, 1996). The product is a pseudo-honnone that promotes ethylene production (Abeles, 1973), which stops fat and protein synthesis and inhibits respiration (MacDonald et al., 1992). Endothall not absorbed by plants is broken down by the metabolism of microbes (Elf Atochem® North America, Inc, 1996). Many lake property owners are intuitively reluctant to use chemicals in their lakes. Since all of the above described chemicals interfere with metabolic processes and stress lakes by stressing most, if not all, of the plants in them (while killing only some of them), some lake property owners are reluctant to use chemicals to control M. spicatum.

In the late 1950s, the U.S. government started a program evaluating biocontrol organisms for aquatic macrophytes (Cofrancesco, 1998), and in the 1960s two diseases (northeast disease and Lake Venice disease) were linked to M. spicatum declines (Painter & McCabe, 1988). Bacteria and fungal pathogens of M. spicatum have been tested and some have shown promise, but exotic pathogens have yet to be released, while native ones do not appear to be able to control M. spicatum without some other M. spicatum weakening agent (Shearer, 2000; Shearer, 2002). The exotic, but nonreproductive, triploid hybrids of grass carp (Ctenopharyngodon idella Valenciennes [Cyprinifonnes:CyprinidaeJ) have been used in many locations to control M. spicatum, but this fish is not a milfoil-specific herbivore. Moreover, it tends to eat other plants preferentially to M. spicatum. Its use in the Northeastern U.S. is typically restricted to isolated impoundments with little chance of carp movement downstream (Pine & Anderson, 1991; Kirk, 2000; Madsen, 2000; Pipalova, 2002; Lubnow et al., 2003). Not surprisingly, recent M. spicatum biocontrol articles focus on M. spicatum insect herbivores.

The yearly cycle ofM. spicatum growth, reproduction, and persistence under the ice is facilitated by carbohydrate storage in the stolons (Titus & Adams, 1979b). Madsen (1993) suggests targeting control attempts to those periods when stored carbohydrates are minimal. Unfortunately, as both he and Titus and Adams (1979b) note, carbohydrate storage and usage patterns vary widely from year to year and from site to site.

Myriophyllum spicatum is reportedly not a management problem in its native range (Center, 1981; Smith, 1982). Spencer and Lekic (1974) reported"...25 insect species feeding on [M. spicatum]." Aiken et al. (1979) noted " ... no insect parasites [herbivores ofM. spicatum] have been reported in North America." That has 12

changed. Although some authors discount their potential (Center, et al., 2002), three North American insects are now identified as having some potential to control M. spicatum: Acentria ephemerella, an aquatic macrophyte moth; Cricotopus myriophylli, the milfoil midge; and Euhrychiopsis lecontei, the milfoil weevil (Kangasniemi et al., 1992; Johnson et al., 1998; Newman et al., 2002; Johnson & Blossey, 2002). Additionally, I have noted that other midges damage milfoil by their overwintering activities (as have others [Kangasniemi & Oliver, 1983; MacRae & Ring, 1993]), but not to the extent that they have the potential for meaningful control, while other researchers have noted similar impacts from other aquatic macrophyte moths (Batra, 1977; Buckingham & Ross, 1981; Newman et al., 1999, Newman et al., 2002).

Aquatic Macrophyte Moth: Acentria ephemerella (Denis and Schiffermiiller) (= Acentropus niveus; =Acentria nivea [Olivier]) (Lepidoptera:Pyralidae)

Batra (1977) first noted an insect in the U.S. with M. spicatum herbivory potential: Acentria ephemerella, the exotic aquatic macrophyte moth. She described A. ephemerella and its behavior in all life stages and its impact on M. spicatum in the field and under laboratory conditions, whereas Berg (1942) provided the most extensive documentation of this moth in its native habitat. Batra concluded that it might have potential for control ofM. spicatum since it damaged stems and ate leaves, but that host preference testing was needed. Buckingham & Ross (1981) provided no-choice testing on a variety of aquatic plants and concluded that A. ephemerella was not specific to M. spicatum and that its dislike of algae-covered M. spicatum limited its potential. Painter & McCabe (1988) concluded that "00.8 larvae per 10 tips had a severe impact" on M. spicatum and could control M. spicatum. Recent Cornell University work (Johnson et al., 1998; Gross et al., 2000; Johnson et al., 2000) has shown that A. ephemerella will eat other aquatic macrophytes, but it prefers M. spicatum and that its presence has facilitated the return to dominance of Elodea canadensis (Michx.) (common waterweed) in Cayuga Lake, NY. Acentria ephemerella was noted to damage apical meristems preventing M. spicatum from reaching the water's surface where it could shade out competing native aquatic macrophytes. Further, Gross et al. (2000) contends that it may have been A. ephemerella, not E. lecontei that was responsible for M. spicatum control attributed to the milfoil weevil in a variety of other studies.

Acentria ephemerella overwinters as a larva in M. spicatum stems or on the growing tips of coontail (Ceratophyllum spp.). Larvae may have as many as six instars with the first instar burrowing into a single dissected vein ofM. spicatum and a second instar forming a shelter, known as a "refuge", out of two adjoining dissected veins (Johnson, 2000). In the spring many larvae end up in the organic debris comprised of decaying aquatic macrophytes from the previous season. They become active at 12 0 _14 0 C (although apparently some are active in cooler water in certain situations [Johnson, 2003]). They eat growing meristems and leaves ofM. spicatum and later instars build refuges out ofM. spicatum leaves. Larvae are almost always found within 25 cm of the apical meristem. Final instar larvae pupate in 13 shelters comprised of leaf material adhered to the stem, the construction of which weakens the stem. After pupation, the adults swim to the surface. The males have wings capable of flight while the females normally possess flightless, vestigial wings which assist in swimming. Females swim about on the water's surface while males rest on surfaces near the water during the day and fly just above the surface at dusk and night (Berg, 1942; Batra, 1977; Painter & McCabe, 1988; Johnson & Blossey, 2002). Mating takes place in seconds when a male finds the female swimming with posterior poised above the water's surface (Buckingham & Ross, 1981; Johnson, 2000). After mating, the female swims down 0.5 m or more and lays eggs along M. spicatum leaves. Adults rarely live more than 48 hours. Although there appears to be no more than two generation of moths per season in the North America, adult moths do emerge every month of the summer, apparently synchronized by moon phases (Berg, 1938; Berg, 1942, Buckingham & Ross, 1981; Lange, 1956; Painter & McCabe, 1988; Palm, 1986; Johnson, 2000; Johnson & Blossey, 2002).

Recently, research has been published on European M. spicatum direct and indirect chemical defenses against A. ephemerella herbivory (Gross et al., 2002; Choi, et al., 2002; Leu, et al., 2002; Walenciak, et al., 2002). This research may provide clues as to how M. spicatum might develop adaptations to avoid control by A. ephemerella.

Milfoil Weevil: Euhrychiopsis lecontei (Dietz) (Coleoptera:Curculionidae)

Following the initial research of Sheldon and Creed (Creed et aI., 1992; Creed & Sheldon, 1994; Creed & Sheldon, 1995; Sheldon & Creed, 1995), mostM. spicatum herbivory research has focused on Euhrychiopsis lecontei, the water-milfoil weevil (e.g., Newman et al., 1996; Sheldon & O'Bryan, 1996a,b; Solarz & Newman,1996; Hutchinson, 1997; Newman et al., 1997; Sheldon, 1997a,b; Sutter & Newman, 1997; Jester, 1998; Tamayo, 1998; Cofrancesco & Crosson, 1999; Jester & Bozek, 1999; Mazzei et aI., 1999; Tamayo, et aI., 1999; Creed, 2000a,b; Jester et al., 2000; Lillie, 2000; Newman & Biesboer, 2000; Tamayo, et al., 2000; Newman et al., 2002; Johnson & Blossey, 2002; Tamayo, 2003). Euhrychiopsis lecontei not only eats M. spicatum, but it destroys the buoyancy of M. spicatum causing stems to drop to the bottom. This interferes with M. spicatum's competitively advantageous ability to form a canopy, which shades out other plant species (Creed et aI., 1992; Creed & Sheldon, 1995; Sheldon & Creed, 1995). Creed and Sheldon (1995) note that E. lecontei evolved on a diet ofnative water-milfoils and suggest that its annual life cycle might be out of synchrony with the exotic M. spicatum. EnviroScience® Incorporporated's MiddFoil™ process augments local populations of E. lecontei and is based on the research of Sheldon & Creed (Hilovsky, 1998; Hilovsky, 2000; Hartzel, 2003). Euhrychiopsis lecontei prefers M. spicatum to native milfoils (Sheldon & Creed, 1995) and develops faster on a diet ofM. spicatum (Newman et al., 1997).

Euhrychiopsis lecontei overwinters as an adult in soils and in organic litter (Creed & Sheldon, 1994; Cofrancesco & Crosson, 1999; Johnson & Blossey, 2002; 14 unpublished data) adjacent to lakes and ponds with Myriophyllum spicatum and/or native Myriophyllum spp. When rising ice-free waters flood the winter habitat or when rising temperatures prompt their return, the adults migrate back to the water and eat growing apical meristems and recently formed leaves (personal observation). After a week or so, the adults mate and, shortly thereafter, the female starts laying an egg or two a day, for the next month, on meristem material (Creed & Sheldon, 1995; Cofrancesco & Crosson, 1999). After 3 -5 days, newly hatched larvae burrow into the stem immediately below the meristem releasing aerenchyma gas that slowly changes M. spicatum's buoyancy from positive to negative (Creed et al., 1992; Newman et aI., 1996). As the larvae grow, they eat increasingly larger diameter tunnels through the stems. Larvae pupate in the stems emerging after nine to twelve days to begin a new generation after a period of eating. The most recent revision of E. lecontei's generation time, under ideal conditions of food and temperature, is 38 days (Newman et al., 1996; Cofrancesco & Crosson, 1999; Newman, 2000).

Adult E. lecontei appear to have difficulty swimming unassisted to depths greater than 25 em (personal observation). They also have no alternative food source when milfoils are not available, establishing a classic predator-prey population cycle (Smith, 1996; Jester, et al., 2000; Johnson, in prep). Additionally, E. lecontei are at risk to fish predation when swimming from plant to plant, as they need to, for mating and egg laying (Sutter & Newman, 1997; Hairston et al., 2000; Cornwell, 2001).

Milfoil Midge: Cricotopus myriophylli (Oliver) (Diptera:Chironomidae)

Least studied of the three herbivores is Cricotopus myriophylli, the milfoil midge. Kangasniemi and Oliver (1983) noted that C. myriophylli caused significant damage to M. spicatum by using apical meristems for food, refuge construction, and pupating sites. Few U.S. researchers have reported finding C. myriophylli (Newman & Maher, 1995; Johnson et al., 2000; Johnson & Blossey, 2002), possibly reflecting the difficulty of observing and identifying these small insects. Kangasniemi (1983) noted C. myriophylli had "potential for use as a biocontrol agent." Further research (Macrae et al., 1990; Kangasniemi, et al., 1992) led to the conclusion that with sufficient numbers of C. myriophylli (approximately one per apical meristem), M. spicatum overall height was reduced and the plants were prevented from surfacing and flowering even while little plant biomass was consumed.

Cricotopus myriophylli are small and their larvae are easily overlooked even when using a stereoscopic dissecting microscope to examine M. spicatum (personal observation). This is particularly true with early instars. Cricotopus myriophylli is not listed in the definitive key of the Cricotopus genus in the Neartic region (Simpson, et al., 1983). Definitive identification involves clearing or crushing head capsules and looking at mouth parts (Oliver, 1984). Other diagnostic methods may suffice seasonally in local situations because of limited local midge diversity (Appendix A) (Berg, 2002). Cricotopus myriophylli eggs have not been located in the field, although they have been collected in laboratory cultures. Cricotopus nd rd th myriophylli overwinter in M. spicatum meristems in dormancy as 2 , 3 , and 4 15

instars, and become active with water temperatures of 10°- 13° C. Four larval instars and a pupae stage precede adulthood. Swarms of adults have been noted flying approximately 3m above the water's surface. Cricotopus myriophylli complete one life cycle a year, but their emergence is not totally synchronized. They can live on a diet of native milfoils leading to a belief that it is a native insect although a seemingly identical insect has been found in Europe (Macrae, 1999). Cricotopus myriophylli may eat other plants when milfoils are not available, but show a preference for milfoils (Macrae et al., 1990; Kangasniemi, et al., 1992; Macrae & Ring, 1993).

Herbivory Potential

Insect herbivores are quite unlikely to eradicate Ai. spicatum in any body of water. Insect milfoil herbivores do, however, have the potential to keep M. spicatum from impeding recreation by keeping it from reaching the water's surface. Some researchers note the presence of more than one herbivore in a body of water. Unfortunately, much of the previously referenced research assumes that only the M. spicatum herbivore of focus caused the impacts noted. If we are to refine our understanding ofM. spicatum herbivory, we need to account for all three herbivores and to focus our research on better defining their interactions and combined impacts on M. spicatum growth.

Fish Predation

Numerous authors have speculated on the impact of fish predation on M. spicatum herbivores (Buckingham & Ross, 1981; Menzie, 1981; Jester, 1998; Creed, 2000b; Lillie, 2000; Newman & Biesboer, 2000; Tamayo et al., 2000; Cofrancesco, 2000). Some have even looked at fish behavior and/or population dynamics in the presence ofherbivores in controlled situations (Newrough, 1993; Sutter & Newman, 1997; Cornwell, 2001; Hairston et al., 2000; Newman, et al., 2002). Cornwell (2001) documented Lepomis gibbosus (pumpkinseed sunfish) predation on E. lecontei. Figure 1, modified from Hairston et al. (2000), provides insight. I know of no previous study which correlates the numbers ofM. spicatum herbivores in M. spicatum infested lakes with the numbers offish of differing species or within year­ classes. Such correlations appear to be factors in herbivore population numbers and may be important biological factors in the ability of the herbivores to control M. spicatum.

Other forms of herbivore predation must also be considered. Bats and even predacious invertebrates (e.g., odonata, hydrazoa, amphipoda, hydracharina, platyhelminthes) are possible limiting factors on herbivore numbers (Batra, 1977; Buckingham & Ross, 1981; Menzie, 1981). 16

E OJ t1 2.0 f-----=-.~------~

cou '0.. ~------",-=-~------~- ro • ~ 1.0 ------'.----~~c__------' .s>!!2 OJ OJ • ~ 0.0 c======:r::::======::::C======~=::::J 0,1 10 100

Mean Numbers of Fish per Trapping Session

Figure 1. Graph from Hairston et al. (2000) illustrating inverse relationship found between fish numbers and Myriophyllum spicatum insect herbivore numbers in Cornell University Research Ponds. Note the logarithmic scale of x-axis.

2001 STUDY: LEBANON RESERVOIR AUGMENTATION

2001 STUDY BACKGROUND

During the summer of2000, nine Madison County, New York lakes were surveyed for the presence of M. spicatum and its herbivores (Harman, et al., 2001 b) while a tenth was known to us by prior research (Harman & Albright, 1997, Harman, et al., 1998, 2000a, 2001a). All but two of these lakes were part of the Old Erie Canal System or of the Chenango Canal System (Welch, 1996). The surveys took place during a summer in which no harvesting was completed on lakes previously harvested regularly. Believing regular harvesting had depleted normal herbivore populations, the survey was undertaken with the intention of identifying a lake which could be successfully augmented with A. ephemerella. Ideally, such a lake would have: (1) few M. spicatum herbivores (particularly, A. ephemerella), (2) large M. spicatum biomass, (3) significant Ceratophyllum spp. (coontail) biomass, (4) alternative food sources (e.g., native Myriophyllum spp., Ceratophyllum spp, or Elodea spp. (waterweeds), and (5) lake shore residents and local municipalities committed to a multiyear augmentation program with a willingness to forgo other M. spicatum control strategies. 17

A lake with a paucity of herbivores and significant M. spicatum biomass would most likely demonstrate M. spicatum reduction after augmentation. Ceratophyllum spp. growing tips are the preferred overwintering habitat for A. ephemerella. The presence of an alternative food source for A. ephemerella would help to ensure their survival at times when their consumption reduced M. spicatum. The commitment of lake stakeholders ensured that alternative M. spicatum control strategies, which might interfere with or obscure the results of an augmentation, would not be implemented (Harman, et al., 2001 b).

None of the nine lakes surveyed provided all the desired conditions; however, Lebanon Reservoir (= Kingsley Brook Reservoir [Welch, 1996]) appeared to have the most potential for a successful augmentation with A. ephemerella. Lebanon Reservoir had the densest M. spicatum beds of the nine lakes. It had M. spicatum herbivores (as did the other lakes), but it had limited shoreline supporting E. lecontei overwintering and that shoreline was largely confined to the north-northwest bay. That limitation in E. lecontei overwintering habitat and the direction of the prevailing winds made it unlikely that E. lecontei alone would ever satisfactorily control M. spicatum in Lebanon Reservoir. Ceratophyllum demersum existed in Lebanon Reservoir in locations with M. spicatum. Additionally, while no native Myriophyllum spp. were found in Lebanon Reservoir, E. canadensis was present in the area proposed for augmentation. Finally, the Lebanon Reservoir Lot Owners Association and Madison County officials were committed to refraining from harvesting and herbicide use for the length of the study (Harman, et al., 200 1b), while State officials provided the permit required for augmentation in Lebanon Reservoir (NYSDEC, 2001).

In light ofthe above, it was decided that A. ephemerella could be introduced into Lebanon Reservoir and that subsequent changes in A. ephemerella and M. spicatum populations could be monitored (Anonymous, 2001).

Lebanon Reservoir (N42°48.190', W75°36.406'), an artificial impoundment built to support the Chenango Canal System, dates back to 1836, although it was rebuilt in 1867 (Welch, 1996). Lakeshore owners tell us that it has been drained several times since, the last time in 1978 (Chase, 2003), although I did not identify any documentation regarding this aspect of the Reservoir's history. The Reservoir is located in the Town of Lebanon and drains into Kingsley Brook. The surface area is approximately 38 hectares (94 acres). The deepest area is about 13.7m (45') (Coastal Environmental Services, Inc., undated). Secchi transparency was 4.0m on 20 June 2000 and 5.0m on 10 August 2000. Emergent vegetation present in 2000 included Polygonum amphibium (smart-weed), Lythrum salicaria (purple loosestrife), and Typha angustifolia (cattail). Submergent species grew to a depth of five meters and were represented by Elodea canadensis (common waterweed), Ceratophyllum demersum (coontail), Potamogeton zosteriformis (flat-stemmed pond weed), Chara vulgaris (muskgrass), Najas flexilis (slender water nymph), Stuckenia pectinata (sago pond-weed), Zosterella dubia (water star-grass), Ranunculus trichophyllus (white water-crowfoot) and Valliseneria americana (tape-grass) as well as two exotic 18 species, Potamogeton crispus (curley-leaved pondweed) and the aggressive exotic species, M spicatum. Aquatic plant distributions and densities as found on July 3, 2002 are summarized in Harman, et al., 2001 b.

2001 STUDY HYPOTHESIS

The 2001 study was designed to test a hypothesis that A. ephemerella, raised in a greenhouse during timeframes when normally dormant, could be introduced into an M spicatum infested lake and survive and reproduce and that they would then reduce M. spicatum and enhance the lake's native aquatic macrophyte community.

2001 STUDY METHODOLOGY

During the winter and spring of2001 Cornell University Research Ponds (CURP) staff cultured late instar larvae ofA. ephemerella (hereinafter referred to as "larvae" and "adults" as appropriate) in greenhouses on the Cornell University Campus.

On May 3, 2001, staff from CURP and SUNY Oneonta Biological Field Station (BFS), as a follow-up to the year 2000 survey, surveyed Lebanon Reservoir, Madison County. Subsequently, three 10m x 10m experimental plots and three 10m 2 x 10m control plots in dense beds (150 - 200 stems/m ) ofM. spicatum were 19 established by mutual agreement between BFS and the CURP personnel (Figure 2).

Site 1

Figure 2. Lebanon Reservoir (from DeLorme 3-D TopoQuads® New York) annotated with Sites 1, 2, & 3, Plots A - F and water quality (WQ) evaluation point. Sites located with GPS readings which have an inherent inaccuracy of less than 22 m (Dana, 2003).

These plots were in depths of 2.5m - 4.0 m of water. Each experimental plot was paired with a control plot to form a numbered site. Approximately 20m separated the control and experimental plots at each site. Experimental plot 1a and control plots 1b (site #1) were about 100m from experimental plot 2c and control plots 2d (site #2) 20 as was site #2 from site #3. Each plot comer was marked by plastic tent pins in the substrate and submersed buoys. A submersed nylon line connected plot comers. Plots were made roughl y square through the use of lines 10m long (for sides) and l4.l4m long (for the diagonal) and with the use of a laser range finder. To facilitate relocating the plots, a line was laid, for later relocation, along the bottom from the plot comer closest to shore toward the closest shore point. This line was terminated in 1 m of water to make plot presence and markers less noticeable. Laser range finder established distances to shore points and Global Positions System (GPS) readings further defined plot locations. Site and plot locations are described in Table 1.

Location North Latitude West Longitude

Site 1 Plot A 42° 47.971 75° 36.548 Plot B 42° 47.975 75° 36.568

Site 2 Plot C 42° 47.991 75° 36.600 Plot 0 42° 47.990 75° 36.621

Site 3 Plot E 42° 47.997 75° 36.600 Plot F 42° 48.004 75° 36.662

Table 1. 2001 Lebanon Reservoir site and plot location data. Sites located with Global Positioning System (GPS) readings which have an inherent inaccuracy of less than 22m (72.2') (Dana, 2003).

On May 18, 2001, four augmentation bundles were placed in the comer of plot 2c to test the efficacy of augmentation bundle design. The augmentation bundles were comprised of an outer nylon net fabric layer, a few stones to provide negative buoyancy, larvae infested M spicatum, and a wire-plastic "twist-tie" (Figure 3). Two of these bundles were retrieved on May 22,2001 and the contents examined and evaluated on May 24, 2001. 21

Figure 3. Acentria ephemerella augmentation bundle design and jars used for transport of bundles.

Five replicate samples for determinations ofbiomass, stem density, and stem length were collected from each of the four plots in three samplings: May 30, July 19, and September 29/0ctober 2,2001. Prior to plant collection, the four comers of the plot were marked by surface buoys. To provide unbiased samples, five Pelican® marker buoys (comprised of a 170 gram lead weight attached to a buoy by a 3.5 mm ­ diameter woven nylon line) were blindly tossed into the plots from a boat. A diver then located the weighted end of each marker buoy and used that weight as the center point for collection. A 0.3m diameter ring attached to a woven mesh bag (with mesh openings approximately 3mm in diameter) was lowered over the aquatic macrophytes which were cut off at the substrate-water interface using utility shears. Alternatively, where cutting the macrophytes endangered the integrity of stems in the sample, plants were pulled from the substrate and later cut off at the lowest level of stem material showing green color. A boat-based assistant collected any buoyant material escaping the net and grasp of the diver. Plant material was placed in plastic bags and stored on ice until returned to the laboratory.

Samples were stored in BFS refrigerators until processed. The samples were first washed in warm tap water to remove mud, animals, weakly adhering algae, and senescent organic material. Root material was discarded. Stems were separated from stolons and rhizomes at the point where the plant material was no longer green. Turions were counted in the sample if they showed green or orange color indicating that they were vegetative products of the current year. Samples were separated by species according to Crow and Hellquist (2000). Myriophyllum spicatum stems were carefully separated, counted, and measured. Myriophyllum spicatum stem pieces were evaluated for recent breaks at one or both ends and, when broken, were matched with the piece from which they were separated. Stem count and stem length figures were adjusted accordingly. To achieve consistent biomass weights, macrophytes were dried at 105°C in a convection oven for at least 24 hours (until dry) and reported 2 as species dry weight/m . Plants were weighed to hundredths of a gram. If a sample 2 weighed less than 0.01 g/m , it was recorded as "*,, to indicate presence in the sample. 22

On May 24, 200 I and every two weeks thereafter until the end of September, twenty-five M spicatum stem samples were collected from each plot using a plant rake designed to minimize damage to plants growing in the plots (Figure 4). The rake was blindly thrust into all areas of the plot, twisted and extracted. Three to five stems were collected off the rake with each thrust. If more than five stems of sufficient length were on the rake only the first five removed were used. To limit bias, each stem was removed from the rake by locating the basal portion without viewing the growing tip. The apical 25cm of each stem was stored in individual plastic bags for later examination for evidence of herbivory. Stem samples were stored on ice until returned to the laboratory. In cases where stem samples could not be examined within two weeks of collection, sam les were frozen and examined later.

Figure 4. Low impact aquatic macrophyte sampler rake designed and built for 2001 research compared with a standard 30.6 cm measuring stick. Rake tip and pipe lengths snap together accommodating collections from various depths. Note the small tines of the rake.

M spicatum stem samples were examined using an earlier version of the methodology described in Appendix A (Lord, 2003) and with dissecting microscopes. Results were recorded on tabular sheets (Johnson, 2000) noting herbivore damage and presence.

On May 30 and June 8, 2001, CURP packaged late instar larvae in 283 and 268 augmentation bundles respectively. Each bundle was assembled with approximately 25 larvae. Bundles were stored overnight and transported in jars (Figure 3) on ice. The counts of four of those bundles, drawn randomly from the stock, were verified for each augmentation date. Bundles were equally distributed amongst the three experimental plots (la, 2c, and 3e) and uniformly distributed within them. 23

Two weeks after augmentation (15 June 2001), in conjunction with collection of the first herbivore stem samples, a diver checked the planted augmentation bundles for evidence of migration out of the bundles. Additionally, M. spicatum growing in the immediate vicinity was viewed for obvious signs ofherbivory.

On 21 June (a day with a new moon), plot comers were noted during daylight hours and a boat based researcher remained on site to observe patterns of emergence and mating in adult moths. Following other July full and new moon dates (5 and 20 July respectively), a survey of shore areas was made to collect moths.

Eight transects used on July 3, 2000 were revisited by free divers (equipped with mask, fins, and snorkel, not SCUBA) on July 3,2001 to determine species composition in various areas of the lake. The divers collected plants and estimated the amount of the bottom covered (substrate percent cover per unit area) by each plant species to characterize littoral vegetation. This enabled us to develop an understanding of the physical attributes (height, density, shape) of the plants in each community. Such data are important to determine their value as cover for invertebrates, forage and game fish and to better understand littoral food web dynamics (ecosystem function) in the lake. Plant community composition and relative dominance was described using six cover-abundance categories (0%-5%, 5%­ 25%, 25%-50%, 50%-75%, 75%-95%, and 95%-100%) for depths of one half, one, two, three, four and five meters. Since many species are able to use nearly 100% of the substrate for their needs concurrently with other species, total percentages per area often exceeded 100%. The principal taxonomic authority for vascular aquatic plants used was Crow and Hellquist (2000).

The Reservoir was also monitored for chemical and physical attributes (Secchi transparency, temperature, pH, conductivity, and dissolved oxygen) ten times during the M spicatum growing season. Data were collected in the deepest part the Reservoir using a standard Secchi disk and a Hydrolab® sampler.

2001 STUDY RESULTS

Myriophyllum spicatum started to grow visibly in the week of 18 May. An estimated (through extrapolation) 21,841 A. ephemerella larvae were transferred into Lebanon Reservoir. (See Tables 2-4). Approximately 4% of the larvae died prior to exiting the transfer packets (Table 5). Although A. ephemerella moths were not found emerging on 21 June as anticipated, winged A. ephemerella (males) were found on surface mats of Stuckenia pectinata (sago pondweed) on days following the next two full moons (5 and 20 July). 24

Table 2. Counts and calculations used to estimate numbers ofAcentria ephemerella larvae and pupae transferred into Lebanon Reservoir on 31 May and evaluated on 1 June 2001. Life Stage Jar: 1 2 3 4 Total Average

Refuges: 35 36 27 26 124 31.00

Larvae alive: 38 25 19 19 101 25.25 dead: 1 3 4 0 8 2.00

Cocoons occupied: 0 3 2 0 5 1.25 empty: 1 0 0 1 2 0.50

Average augmentation of moth larvae & pupae / package: 26.5 Augmentation packages introduced: 279 Total estimated augmentation to date: 7394

Table 3. Counts and calculations used to estimate numbers ofA. ephemerella larvae and pupae transferred into Lebanon Reservoir as of 8 June and evaluated on 11 June 2001. Life Stage Jar: 1 2 3 4 Total Average

Refuges: 34 27 37 32 130 32.50

Larvae alive: 36 17 23 26 102 25.50 dead: 4 1 4 3 12 3.00

Cocoons occupied: 2 1 1 0 4 1.00 empty: 0 0 0 0 0 0.00

8­ 8­ 7­ 7­ Date packaged: Jun Jun Jun Jun

Average augmentation of moth larvae & pupae / package: 26.5 I Augmentation packages introduced: 268 Total estimated augmentation: 7102 Total estimated augmentation to date: 14496 25

Table 4. Counts and calculations used to estimate numbers ofAcentria ephemerella larvae and pupae transferred into Lebanon Reservoir as of 14 June and evaluated on 15 June 2001. Life Stage Jar: 1 2 3 4 Total Average

Refuges: 36 45 41 32 154 38.50

Larvae alive: 27 33 25 21 106 26.50 dead: 0 0 0 0 0 0.00

Cocoons occupied: 4 0 3 0 7 1.75 empty: 0 0 0 0 0 0.00

Cricotopus myriophylli 0 0 0 1 1 0.25

Average augmentation of moth larvae & pupae / package: 28.25 Augmentation packages introduced: 260 Total estimated augmentation: 7345 Total estimated augmentation to date: 21841

I

Table 5. Counts and calculations used to estimate numbers of surviving augmented Acentria ephemerella larvae and pupae in Lebanon Reservoir. Four samples were retrieved from the 31 May (Plot F) introduction on 14 June and evaluated on 18 June 2001. Life Stage Bags: 4

Refuges: 45 Remaining

Larvae alive: 10 dead: 4

Cocoons occupied: 1 empty: 1

Average augmentation of moth larvae & pupae/package at introduction: 27.10 Average live moth larvae & pupae/package when examined: 2.75 Average dead larvae: 1.25

Stem data are summarized in Table 6 which shows approximately 0.23 A. ephemerella larvae were available for each stem of M. spicatum in the experimental plots following augmentation. 26

Table 6. Lebanon Reservoir Acentria ephemerella larvae per stem calculations. Calculated augmentation of moth larvae & pupae: 21841.00 Calculated introduced moth larvae & pupae dead: 1008.75 Calculated introduced moth larvae & pupae alive: 20832.25 Alive introduced moth larvae & pupae / experimental plot: 6944.08

Introduced Larvae Plot Stems/m2 & Pupae / Stem A 237.5 0.29 B 345.0 0.00 C 387.5 0.18 D 240.0 0.00 E 302.5 0.23 F 265.0 0.00

Average introduced larvae & pupae / stem in experimental plots: 0.23 Average stems / introduced larvae & pupae in experimental plots: 4.28 Expectation of larvae & pupae in 20 tip samples: 4.67

Larvae were found in control plots throughout the sampling period, although they averaged only .045 per stem of M. spicatum (Figure 5). Greater numbers of larvae were present in experimental plots than were found in the control plots during June and July (Figure 6), but not in the numbers anticipated by calculations (Table 6). Moreover, in succeeding months the numbers of larvae in these plots were nearly indistinguishable from those found in the control plots (Figures 5 & 6). Finally, few empty refuges (30 in the approximately 1500 stems examined) were found on M. spicatum stem samples.

Plant diversity across the Reservoir increased in 2001 (Lord, 2003) when compared to 2000 (Harman, et al., 2001 b) with five transects showing more diversity and two showing less. Still, M. spicatum was anecdotally, but clearly, more recreationally impeding across the Reservoir in 2001 than it was in 2000. Water levels were also clearly lower than 2000 (although the difference was not measured). Myriophyllum spicatum formed canopies and branched at the surface, flowered, and then produced seed frustrating efforts to use the Reservoir for boating, swimming, and fishing.

Standard physical and chemical data accumulated over the season were reported in Lord (2003).

Lepomis maerochil1ls (Rafinesque) (Perciformes: Centrarchidae) (bluegill) were noted to be present in large numbers in Lebanon Reservoir during all research activities. Additionally, at least 12 transfer packets (see Figure 3) were incidentally observed to have "netted" small L. macrochil1ls. 27

E 2 (II

(I) --co Moth emoegeoce 0.. 0.2 ­ ~ I 0.. ~ (I) co c: l!l 0.1 ­ '0 ..... (I) ~ ~ z 0.0 ­ ----~---~~j------~~ ------~b~bb~b6~~b~~b~~b~~b~~b~~b~~b~ 22 May 21 Jun 1BJui l7Aug 200cl 8 Jun 9 Jul 3 Aug 21/29 Sep 8 Dec Control Rots on Date I'Joted

Figure 5. Acentria ephemerella larvae per stem sampled on ten different 2001 dates in Lebanon Reservoir control plots.

E 2 (II

(I) co 0.2 ­ 0­ :J 0­ ~ (I) co ~ 0.1 ­ co '+­o ..... (I) ~ :J Z 0.0 ­ - -- Ab~Ab~Ab~Ab~Ab~Ab~Ab~Ab~Ab~Ab~ 22 Mai' 21 Jun 19 Jul 17 Aug 20 Oct 8 Jun 9 Jul 3 Aug 21/29 Sep 8 Dec Augrrented Rots on Date Noted Figure 6. Acentria ephemerella larvae per stem sampled on ten different 2001dates in Lebanon Reservoir augmented plots. 28

2001 STUDY DISCUSSION OF RESULTS

Initial A. ephemere//a availability in the test plots was at a density of0.23/M. spicatum stem. This was encouraging since, if the succeeding generation of larvae were recruited at a rate of 10: 1, there should be noticeable impact on the M. spicatum in and around the test plots (Painter and McCabe, 1988).

Acentria ephemere//a did not emerge on 21 June as expected. This may be due to unusually cool water temperatures in late May and early June slowing down A. ephemere//a metabolism and growth. They did emerge in July following full and new moons.

As noted previously, M. spicatum herbivore predation probably comes from a number of animals representing various taxonomic groups. We need not, however, focus on all predators. We should identify those predators that exert significant control on M. spicatum herbivores. The presence of numerous male A. ephemere//a on the canopied S. pectinata plants in shallow water after emergence indicates that predation comes from below, not from above the water's surface. Additionally, there is evidence disputing a hypothesis that predatious invertebrates were significant in reducing the A. ephemere//a population in Lebanon Reservoir: The near absence of empty (old; abandoned) refuges on the plants in the experimental plots is inconsistent with a relatively small predator and more consistent with a large predator; one which associates the refuge shape with food and which is capable of removing the refuge. This coincides with an observation made by Johnson (2003) thatA. ephemere//a refuges, originally present when L. macrochirus were put in aquaria with M. spicatum and A. eplzemere/la, were missing from M. spicatum stems at the end ofthe experiment.

Physical and chemical data accumulated over the season indicated nothing significant to the augmentation (Lord, 2003).

2002 STUDY: COMPARISON OF TWO LAKES

2002 STUDY BACKGROUND

During the warm water months of2002, a monitoring regime was implemented in two M spicatum dominated lakes to facilitate comparisons ofthe fish populations and herbivore numbers, and M. spicatum dominance and herbivore numbers. The lakes were Lebanon Reservoir where M spicatum forms canopies regularly and Otsego Lake (adjoining the BFS) which, while M spicatum dominated, suffers minimal recreational interference from M. spicatum growth. Lebanon Reservoir was described previously. Otsego Lake (described in Harman et al. [1997]) differs from Lebanon in both depth and overall size. Lebanon Reservoir aquatic macrophytes have been managed extensively (harvesting [Chase, 2002J and milfoil moth augmentation as described above) while Otsego Lake's macrophytes have not been managed. Although Otsego Lake's morphological character differs 29 considerably from Madison County reservoirs, the contrasting characters of the M. spicatum communities in both of these lakes still invited comparison. While a greater number oflakes may have provided more statistically compelling data, 2002 funding constraints restricted my work to these two lakes.

2002 STUDY METHODOLOGY

The following were compared in the two lakes studied: (1) warm water fish populations, (2) aquatic macrophyte community composition, (3) M. spicatum herbivore populations, and (4) chemical and physical parameters.

Warm water fish populations were evaluated by night electrofishing in late June (Otsego Lake) and early July (Lebanon Reservoir) using the SUNY-Cobleskill Smith-Root™ boat electrofisher. This system uses a 3500-watt generator and a Type VI-A variable voltage pulsator to stun fish which were collected by two individuals, with scap nets, in the bow of the boat. During these surveys, 336-504 DC volts at 6­ 7.5 amps were used (Cornwell, 2003). Data were recorded by species and total length as determined by measurement on a measuring board. Electrofishing was conducted around the entire littoral ofboth Lebanon Reservoir and Otsego Lake.

Lebanon Reservoir fish ages were estimated on fish species that were captured in quantities greater than ten by a length-frequency analysis (Murphy & Willis, 1996) whenever the data supported such estimates.

Aquatic macrophyte community composition and herbivore populations were examined in the south end of Otsego Lake (which is more morphologically similar to Lebanon Reservoir than other areas of Otsego Lake) and around the entire periphery of Lebanon Reservoir. In each lake, M. spicatum was sampled for biomass, stem length, and stem densities, as well as the biomass of other aquatic macrophytes during July (the peak timeframe for M. spicatum growth). Herbivore numbers in each lake were monitored by sampling and analyzing no less than 25 stems from thirteen randomized littoral locations in each lake at four different time periods from July through October.

Sampling location randomization was accomplished though a multistep process. A map ofthe overall sampling area in each lake was interpolated between the 10' (3m) and 20' (6m) depth contours to identify a IS' (4.6m) contour. A 4.6m contour would nearly coincide with the deepest depth for plant growth (deep edge of the littoral zone). Grid boxes were then overlaid on those portions of the lake maps between 3m and l4.6m and each was assigned a unique number (Figures 7 & 8). A random number generator (Microsoft Office XP Excel19) was used to provide sample location grid numbers. Those grid number locations were identified on a topographic map ofthe lake areas (Delorme 3-TopoQuads: New York19). Latitude and longitude coordinates were identified. Coordinates were used on the lakes with a handheld GPS 19 unit (Garmin GPS II Plus19 or Garmin GPS 76 ) to identify sampling locations. 30

Where locations identified by this procedure were too deep to grow plants, a rake was tossed every 2 m, towards the closest shore point, until plants were collected.

Five replicate samples for determinations of biomass, stem density, and stem length were collected from each lake in July: 18 July for Lebanon Reservoir and 22 July for Otsego Lake. A Pelican® marker buoy (previously described) was tossed into the lake, from a boat, at the location identified by the randomization procedure. A diver then located the weighted end of the marker buoy and collected plants using previously described procedures. 31

_ 3~

,"" \} (~" 7:>, • I ~ )1 .;', r! '?'f,"'t"t:"':( ,~ 3"(':; qi, 1'/'~ :""~.~

.'':;' '"i.

IO~,I(,"'i

r530

Figure 7. Otsego Lake grid pattern for 2002 aquatic macrophyte and herbivore sampling. 32

!,,~. ..,~ - ,z,

:: " ., ~ ~

J / / It'!' lIq \\6 l\e, II, IH \11 lit

,10 (M \~."

\.

Figure 8. Lebanon Reservoir grid pattern for 2002 aquatic macrophyte and herbivore sampling. 33

Plant samples were transported, stored, and processed for biomass, stem density, and stem length as in the 2001 work described above. Both lakes were also monitored for chemical and physical attributes at least five times during the M. spicatum growing season as described previously.

2002 STUDY RESULTS

Significant results from the 2002 research are displayed in abbreviated form in Figure 9.

Plant biomass samples from both lakes contrasted with each other. Myriophyllum spicatum was missing from four of the five Otsego Lake samples while it was present in all Lebanon Reservoir samples. Density of stems in Lebanon Reservoir averaged 295/m2 (SE=80.3) while density of stems in Otsego Lake was 301m2 (SE=30.0). Mean height of stems in Otsego Lake and Lebanon Reservoir were 55.0 cm (SE=10.9) and 109.5 cm (SE=9.0) respectively.

Myriophyllum spicatum stem samples taken to assess herbivory were similarly varied. Otsego Lake samples showed clear signs of herbivory on 83% of the samples processed while Lebanon Reservoir processed samples showed herbivory on 21 %. The 100 Otsego Lake samples produced nine A. ephemerella, eight E. lecontei and 38 C. myriophylli while the 100 Lebanon Reservoir samples held two A. ephemerella, three E. lecontei and one C. myriophylli.

Lebanon Reservoir Otsego Lake

Biomass - M. spicatum present - M. spicatum absent in all sites. in some samples. Stem Samples - Meristems clean; - Meristems chewed; - Herbivores rare. - Herbivores present.

' - Few spp.; - Diverse fish EI trofi h ec smg - D'omlna tdbL e y. community; macrochirus. - Few L. macrochirus; - Dominated by alewives. ~~j(

Figure 9. Results of2002 research comparing Lebanon Reservoir and Otsego Lake Myriophyllum spicatum, M. spicatum herbivores, and fish. 34

Standard chemical and physical data for Lebanon Reservoir in 2002 are included in Lord (2003) and the same data for Otsego Lake are summarized in Albright (2003).

Electrofishing results for Otsego Lake are described in detail in Cornwell (2003), with Table 7 providing a summary of those data. Table 8 summarizes the fish caught in Lebanon Reservoir. Length frequency scatter plots of Lebanon Reservoir fish caught are included in Lord (2003). 35

Table 7. Otsego Lake e1ectrofishing catch rates (catch I hour) for game and non­ game fish for June 2000, October 2001, June 2002 and October of 2002 (modified from Cornwell [2003 J). Lepomis macrochirus and Alosa pseudoharengus data are bo1ded. Species Jun-OO Oct-01 Jun-02 Oct-02

Sander vitreus (Walleye) .7 1.5 1.2 1.4 letalurus nebulosus (Brown Bullhead) 4.5 1.7 0.8 10.0 Lepomis macrochirus (Bluegill) 11.0 30.7 15.2 32.0 Cyprinus carpio (Common Carp) 4.0 4.0 10.4 3.0 Alosa pseudoharengus (Alewife) 123.0 2.7 136.0 1.0 Notropis artherinoides (Emerald Shiner) 6.0 6.7 3.2 88.0 Notemigonus erysoleueas (Golden Shiner) 3.5 11.3 5.6 5.0 Lepomis gibbosis (Pumpkinseed) 31.0 46.0 17.6 25.0 Lepomis auritus (Redbreasted Sunfish) 2.0 14.7 6.4 28.0 Notropis hudsonius (Spottai1 Shiner) 3.0 12.7 0.0 0.0 Etheostoma Olmstedi (Tesselated Darter) 1.0 10.0 4.0 6.0 Catastomas eommersoni (White Sucker) 28.0 8.7 10.4 11.0 Salvelinus namayeush (Lake Trout) 0.0 2.8 0.0 12.0 Salmo salar (Atlantic Salmon) 0.0 0.7 0.0 0.0 Salmo truUa (Brown Trout) 3.5 1.0 0.5 0.6 Amblopleites rupestris (Rockbass) 24.5 94.0 11.9 32.0 Esox niger (Chain Pickerel) 3.3 12.3 2.7 5.1 Mieropterus salmoides (Largemouth Bass) 14.2 14.2 11.4 6.2 Mieropterus dolomieui (Smallmouth Bass) 16.0 6.1 9.0 4.9 Perea jlaveseens (Yellow Perch) 26.0 22.0 7.2 7.1

Table 8. Lebanon Reservoir electrofishing catch rates for game and non-game fish for July 2002. Lepomis macrochirus data are bo1ded.

Species Catch/hr

lctalurus nebulosus (Brown Bullhead) 14.1 Lepomis macrochirus (Bluegill) 442.4 Notemigonus crysoleucas (Golden Shiner) 14.1 Micropterus salmoides (Largemouth Bass) 123.6 Lepomis gibbosis (Pumpkinseed) 82.4 Amblopleites rupestris (Rockbass) 23.6 Etheostoma Olmstedi (Tesselated Darter) 1.2 Catastomas commersoni (White Sucker) 2.4 Perca jlavescens (Yellow Perch) 3.5 36

2002 STUDY DISCUSSION OF RESULTS

Interpolation of depth gradients for the lakes and locating lake points on Delorme Topoquads maps used in conjunction with handheld GPS devices frequently introduced inaccuracies that directed collections to locations deeper than the plants grew. Use ofa 10' (3m) depth gradient would have simplified sampling and focused sampling on the depth at which M spicatum is the most dominant in both lakes (personal observation) and at which M spicatum is known to grow best (Hartleb et al., 1993).

Physical and chemical data accumulated over the season indicated nothing significant to the comparison.

Summer electrofishing protocols commonly used to describe the warm water fish community in NY State lakes (Brooking, et al., 2001) are not appropriate for sampling all fish species. Cold ,vater species such as the Salmo gairdneri (rainbow trout) found in Lebanon Reservoir (Chase, 2002) are not sampled in summer electrofishing because these fish are found in deeper, colder waters. Some warm water fish such as Pomoxis sp. (crappie), which are commonly caught in Lebanon Reservoir (Chase, 2002), will avoid sampling if they are in deeper waters than the effective range of the electrofisher unit. Neither of these two fish was accounted for in 2002 electrofishing sampling (although Pomoxis nigromaculatus was accounted for in 2003).

Best fish aging techniques vary by species and by the environment in which the fish are found (Murphy & Willis, 1996). Many require sacrifice of the fish aged. One technique supported by the governing 2002 New York State Department of Environmental Conservation (NYSDEC) permit for Lebanon Reservoir was a length­ frequency analysis. This analysis assumes a normal distribution of the data obtained that is rarely justified. The Lebanon Reservoir data was not normally distributed. A particularly consistent limitation to the use of this technique is that older fish year­ classes are hard to differentiate due to their limited growth. Nevertheless, I observed an indication of year-classes in some of the Lebanon Reservoir species collected.

Lepomis macrochirus were, by far, the most numerous fish present in the electrofishing survey. Those netted appeared to be represented by at least four year­ classes in approximate lengths of: 30mm - 75mm (1.2" - 3.0"), 75mm - 140mm (3.0" - 5.5"), 140mm - 170mm (5.5" - 6.7"), and 170 mm (6.7") and larger. Smaller L. macrochirus were not expected inasmuch as L. macrochirus smaller than 30mm (1.2") are typically limnetic fish (Layzer, 1982; Hayse, 1991) while electrofishing was confined to the littoral area of the lake shallower than 1.5 m. The largest L. macrochirus netted (= 170mm [6.7"]) are somewhat larger than the range oftypical adults found in NY State but none were large enough to be considered trophy fish (Smith, 1985). These larger fish were, almost certainly, not from a single year-class, but are fish that are older than the age of the year-class preceding. 37

Micropterus salmoides (largemouth bass) is an important fishery in Lebanon Reservoir (personal observation). Micropterus salmoides were well represented in the survey and appear to be present in five size classes approximately defined as: l5mm - 50mm (0.6" - 2.0"), 75mm - l20mm (3.0" - 4.7"), l70mm - 270mm (6.7"­ 10.6"), 270mm - 350mm (10.6" - 13.8"), and bass greater than 350mm (13.8"). This correlates well with the fact that M. salmoides typically take five years to reach maturity in NY State. Successful recruitment of this game fish in Lebanon Reservoir is apparent. The largest M. salmoides caught, exceeding 51 Omm (20"), is not a NY State trophy fish (Smith, 1985). Interpretation of year class data for other Lebanon Reservoir fish species encountered provided nothing of note to this research but is contained in Lord (2003).

Although few in number, all three M. spicatum herbivores persisted in Lebanon Reservoir. The simplicity of the warm water fish community in the Reservoir and the large number ofL. macrochirus present forced attention to L. macrochirus as the key predator on the M spicatum herbivores present and prompted a review of the literature available on L. macrochirus. Lepomis macrochirus is native only to the Saint Lawrence drainage in New York State but has now been introduced into lakes across the State (Smith, 1985). Sadzikowski (1976) notes, in an article section entitled, "Food of small sunfish (29-70mm)", that the " ...predominant food items (volume and frequency) used by small [L. macrochirus] were chironomid larvae (Chironomus sp. and Cricotopus sp.)." These would include Cr. myriophylli and these larvae would closely resemble in form and habit larvae ofA. ephemerella and E. lecontei. O'Brien et al. (1976) notes that bluegill"...always choose moving prey over one held motionless." while Werner & Hall (1976) note that L. macrochirus " ... fed largely on vegetation dwelling prey." I also notice that Werner & Hall (1977) noted L. macrochirus were"...found in water... 1-6m deep" which is the same depth range that M. spicatum becomes problematic in Lebanon Reservoir (and most NY State lakes) and that L. macrochirus possess a"... protrusible mouth which permits efficient exploitation of small prey" and that these sunfish use"...precise maneuvering for prey which must be gleaned in large numbers from vegetation..."

Lepomis macrochirus are standouts among the sunfishes found in New York state because their stomach contents are noted to contain ingested plants (McCormick, 1940; Bennet et al., 1940; Howell et al., 1941; Rice, 1941; Flemer & Woocott,1960). Interestingly, bluegills do not digest plants (Chable, 1947). Why are the plants included in their intake? Sadzikowski (1976) notes the possibility that the vegetation may be incidentally ingested when feeding on insects hiding among plant parts.

Lepomis macrochirus in M. spicatum are safer from predation from piscivorous fish than L. macrochirus in more diverse situations (Gotceits & Colgan, 1987; Hayse, 1991; Hayse & Wissing, 1996; Valley & Bremigan, 2002b). Lepomis macrochirus live among aquatic macrophytes throughout their lives when in the presence ofM. salmoides large enough to eat them, except for the first six or seven 38

weeks of their lives which is spent in limnetic zone where they eat zooplankton (Siefert, 1972; Layzer, 1982; Hayse, 1991; Breck, 1993).

An explanation as to the differences in M. spicatum canopies in Otsego Lake and Lebanon Reservoir may lie with the presence of another exotic species, a fish, in Otsego Lake. Alosa pseudoharengus (alewives) are limnetic, planktivorous fish with a predilection towards opportunistic feeding on young-of-the-year fish (Brooking et al., 1998; Brooking et al., 2001). Lepomis macrochirus numbers in Otsego Lake may be depressed due to A. pseudoharengus predation on just hatched L. macrochirus in the limnetic zone. Lowered numbers ofL. macrochirus may be facilitating a healthy population of M. spicatum herbivores which keeps Otsego Lake M spicatum from forming a canopy. In Lebanon Reservoir, with no A.pseudoharengus, L. macrochirus are suppressing the M. spicatum herbivore population facilitating M spicatum canopy production which assists L. macrochirus in avoiding predation by M. salmoides. This M. spicatum assistance in L. macrochirus success which facilitates M. spicatum success is an example ofboth a positive feedback cycle and mutualism (Smith, 1996). This hypothesis is illustrated in Figure 10.

• L. macrochirus t • L. macrochirus.

• M. spicatum • M. spicatum herbivores • herbivores t

• M. spicatum t • M. spicatum • (Lebanon Reservoir) (Otsego Lake)

Figure 10. Hypothetical model illustrating understood trophic relationships between Lepomis macrochirus, Myriophyllum spicatum herbivores, and M spicatum as perceived from Otsego Lake and Lebanon Reservoir 2002 data. Up-arrows indicate increased population sizes whereas down-arrows indicate decreased populations.

While the hypothesis proffered above should be considered, we should be careful not to accept its implied remedy without deliberate consideration. Eliminating L. macrochirus from a body of water is problematic because these fish are ubiquitous, an appreciated pan fish, and a prolific reproducer. Even if L. macrochirus could be removed from and kept out of a lake, niche shifting (Smith, 1996) must be considered 39 a possibility. What niche shift means in the context ofM. spicatum control is that some other predaceous pan fish (e.g., Perca jlavescens [yellow perch] or Lepomis gibbosis [pumpkinseed]) might crop M. spicatum herbivores in the absence ofL. macrochirus and, even if not as efficiently as L. macrochirus, may suppress M. spicatum herbivore numbers. Werner & Hall (1976; 1977) have previously demonstrated niche shifting amongst sunfishes.

Additionally, obvious solutions may have benefits negated by problems created. As an example, introducing A. pseudoharengus into Lebanon Reservoir might serve to suppress the L. macrochirus numbers facilitating M. spicatum herbivore survival and M. spicatum control, but A. pseudoharengus come with a suite of their own problems including increased nutrient cycling, lowered water transparency, and depressed oxygen levels (Warner, 1999). Their introduction would jeopardize the already marginal habitat offered the currently stocked S. gairdneri in the Reservoir. It is not even clear that A. pseudoharengus could crop the L. macrochirus numbers in Lebanon Reservoir sufficiently given the greater proportion of littoral to limnetic surface area in the Reservoir as compared to Otsego Lake (Brooking, 2002).

2003 STUDY: COMPARISON OF EIGHT LAKES

2003 STUDY BACKGROUND

Our 2002 research provided some reasonable indications that L. macrochirus may be responsible for suppressed M. spicatum herbivore populations facilitating M spicatum canopies and dominance. Nevertheless, the 2002 research examined only two lakes. While the results were intriguing, they did not include enough data for statistical validity. Further research needed to be undertaken to determine if statistically significant correlations existed between fish populations, M. spicatum herbivore numbers and M. spicatum dominance.

Funding was obtained (Anonymous, 2003) to monitor eight Madison County, New York reservoirs in May, June and July of2003: Bradley Brook Reservoir, Eaton Brook Reservoir, Hatch Lake, Lebanon Reservoir, Lower Leland Pond, Upper Leland Pond, North Basin Lake Moraine, and Tuscarora Reservoir. Monitoring tasks included evaluating chemical and physical parameters, fish populations, M. spicatum herbivore numbers and M spicatum dominance.

2003 STUDY METHODOLOGY

Techniques used in 2003 were nearly identical to those used in 2002. Warm water fish populations were evaluated by night electrofishing in late June in all lakes. Electrofishing was done around the entire littoral zone ofBradley Brook Reservoir, Hatch Lake, Lebanon Reservoir, Lower Leland Pond, North Basin Lake Moraine and Upper Leland Pond. The littoral perimeters of Eaton Brook Reservoir and Tuscarora Reservoir were too large to be electrofished in one night. In both lakes the shallow 40 sloped organic sediment areas and steep rocky bottom areas were sampled with the preponderance of sampling taking place in shallow sloped organic sediment areas. Specific areas electrofished are identified in Lord et al. (in prep).

Aquatic macrophyte community composition and herbivore populations were examined by sampling in randomized locations (as previously described), but only along the 3m depth contour, simplifying the procedure used in 2002. Sampling at the 3m depth also provided samples from the depth at which M spicatum grows most profusely in North America (Hartleb, et al., 1993). Biomass samples were collected from 20 sites in each lake in early July using the 2002 procedure, but only along the 3m depth contour. Results are reported for 1.0 m2 while 1.41 m2 was sampled in each lake. Herbivore numbers in each lake were monitored by sampling and analyzing 25 stems from no less than thirteen randomized littoral locations in each lake at four different time periods from May through July. In some instances all 25 stem samples could not be accounted for and the lake's results were recalculated as a percentage of 100 stems so that each lake was equally weighted.

Data were tabulated and analyzed using Excel® (Microsoft® Office Professional Edition 2003) and MINITAB™ (Version 13.1). Data were initially compared to M. spicatum percentage of biomass collected at 3m, a measure of dominance, and later, following initial data analysis, compared to M. spicatum stem density at 3m. Statements of significance refer to P = 0.05. Residuals for all such P values were checked for normality.

2003 STUDY RESULTS

Principal results from the 2003 research were statistical significance for regressions between both L. macrochirus and L. gibbosus and M. spicatum stem density, logarithm transformed A. ephemerella, and damage to M. spicatum stems, and between M. spicatum stem density and logarithm transformed A. ephemerella. Table 9 provides regression specifics.

A wide range of M. spicatum densities (percent of biomass and stem counts) existed in the surveyed lakes. Lebanon Reservoir had 99% M spicatum in its 3 m depth biomass samples with a stem count of 297 while Eaton Brook Reservoir had 6% and 12. Significant regressions were found between density ofM. spicatum stems at 3 m and percentage of biomass, average length of stems, M. spicatum biomass, and total biomass (Table 10). All three herbivores were found in all lakes with varying degrees of herbivory evident. Fish populations varied significantly. Table 11 provides a contrast ofM spicatum percentage of biomass at 3 m and notes on lake fish. Table 12 provides a summary of all data collected. Lord, et al. (2004) provides details regarding plant community structure and the physical and chemical data collected as well as tabulated electrofishing data by species and location for all lakes. 41

Not found to be significant were the relationships between the data for E. lecontei and Lepomis spp. (or any other fish) and between C. myriophylli and Lepomis spp. (or any other fish).

Table 9. Statistically significant regression equations defining the trophic relationships between Lepomis macrochirus and L. gibbosus, Acentria ephemerella, and Myriophyllum spicatum as calculated from 2003 Madison County lakes data. 2 I Regression Equation P R

M spicatum stems at 3m = 44.8 + 0.25 L. macrochirus / hour electrofishing 0.001 87.3% -63.7 + 1.43 L. gibbosus / hour electrofishing 0.006 74.5%

M spicatum stems at 3m = 244.45 -logarithm transformed A. ephemerella (no eggs) 0.006 74.7%

Logarithm transformed A. ephemerella (no eggs) = 0.884-0.001 L. macrochirus / hour electrofishing 0.001 85.9% 1.249 - 0.005 L. gibbosus / hour electrofishing 0.024 59.8%

Damaged M spicatum stems at 3m = 59.2170 - 0.0269841 L. macrochirus / hour electrofishing 0.011 68.5% 70.0021 - 0.145587 L. gibbosus / hour electrofishing 0.039 53.6% 42

Table 10. Regression equations for Myriophyllum spicatum stems at 3 m and M. spicatum percent of total biomass at 3 m, average M. spicatum stem length at 3 m, M. spicatum biomass weight at 3 m, and all plants biomass weight at 3 m. M. spicatum stems at 3 m = P R2

- 38.6 + 2.86 M. spicatum % of total biomass 0.004 76.8% 48.0 + 0.730 M. spicatum biomass weight 0.007 73.5% - 68.2 + 2.13 average M. spicatum stem length 0.031 56.6% 35.1 + 0.595 all plants biomass weight 0.035 55.0%

Table 11. Myriophyllum spicatum percent of biomass at 3 m and notes regarding fish contrasted for eight Madison County, NY lakes in 2003. I Not included in electrofishing data; observed while obtaining biomass samples. Lake Milfoil % of Biomass at Fish Notes 3m

Eaton Brook Reservoir 6% Large S. vitreus. Bradley Brook Reservoir 17% No L. macrochirus; S. vitreus 1 present • Tuscarora Reservoir 28% Numerous S. vitreus. Hatch Lake 44% No L. macrochirus; S. vitreus present. Lower Leland Pond 53% A/osa pseudoharengus; big & medium L. macrochirus. Upper Leland Pond 82% A/osa pseudoharengus; big & medium L. macrochirus. Lake Moraine (Upper 85% L. macrochirus abundant Basin) Lebanon Reservoir 99% Numerous L. macrochirus. 43

Table 12. Principal results of May - June 2003 monitoring in eight Madison County, NY lakes. BB = Bradley Brook Reservoir; ER = Eaton Brook Reservoir; HL = Hatch Lake; LLP = Lower Leland Pond; LM = Lake Moraine Upper Basin; LR = Lebanon Reservoir; TL = Tuscarora Lake; ULP = Upper Leland Pond. Fish species numbers = catchlhour of electrofishing. Plant biomass derived from 20 random samples from each lake in July with a total of 1.41 m2 sampled. Results reported for 2 1.0 m . Stem samples are for 100 stems collected randomly in four different collections of 25 throughout the study timeframe. Where all 25 samples were not accounted for, the remaining samples were averaged for 25. Lepomis macrochirns and L. gibbosus are bolded for emphasis. BB ER HL LLP LM LR 1R ULP

Fish Species I AIo,a p,eudoharengus 00 0.0 00 68.9 00 00 00 81.2 2 Ambloplite, rupe,tri, 4044 1887 2987 218 1.3 <163 2006 39.2 3. Cato,tomm commer,oni 00 80 40 00 24.8 154 218 238 4· Cyprinu, carpio 24 6.0 1.3 80 170 00 5.9 16.8 5.Erimyzon oblongu' 00 00 00 57 00 0.0 00 84 6· Etheo,toma olm,tedi 00 33 1.3 00 00 00 9.2 00 7.Flmdulus diaphanu, 10.8 30 00 00 0.0 17 17 00 8 Jctalurus spp. 37.2 80 200 80 143 120 26.0 5.6 9 Lspolftis ~hhOSllS 67.2 5611 10811 1069 259.6 1809 111.6 839 10 Lspolftis lftQcrochi17lS OIl 44.7 OIl 64.3 106004 775.7 79.7 47.6 11· Micropterus dolomieui 75.6 373 600 00 00 00 35.2 00 12' Micropterus salmoide, 216 320 347 32.2 470 1294 613 196 13 :Notemigonus cry,oleucas 9.6 6.0 40 1.1 117 120 101 84 14 Notropis artherinoides 00 2920 0.0 00 00 00 7800 00 15· Notropi, hud,onius 00 00 00 00 00 00 25 00 16 Percaj1avescens 276 453 1053 147.1 65.2 26 143 784 17 Pomo);i, nigromaculatus 00 20 00 00 13 2.6 0.8 00 18 Sander vitreus 0.0 40 27 00 00 00 101 00 19 Unknown fish 0.0 00 00 00 00 00 25 00 20. Unknown minnow 00 27 00 00 00 00 50 00 Unknown small sWlfish 00 00 00 57 24.8 334 0.8 14

Fish total 6564 7390 640.0 4700 15274 12120 1379.2 333.0

# offish species 16 II 10 11 10 18 11

118Jlt Biomass per 10m2 'Total Biomass (V 865 43.8 34.6 9.2 3177 1199 50.8 497 Myriophyllum spicatum 14.8 2.8 15.1 4.9 269.1 118.8 145 40.8 Biomass % ofTotal Biomass 17.2 63 437 534 847 99.1 285 82.1 Average M. 'picatum 470 568 705 344 1416 1090 797 129.6 Stem Length M. spicatum Stems in samples 29.8 85 29.8 433 1908 2106 277 830

StemSamples A. ephemerella (no eggs) 50 4.0 133 60 00 10 10.4 8.0 A. ephemerella with eggs 1270 30 133 60 2.1 10 323 90 C. myriophylh 12.0 15.2 5.1 10.0 6.2 10.0 63 12.0 E .lecontel (no eggs) 90 212 112 00 00 60 167 17.0 E. Iecontei with eggs 120 303 133 40 20.6 130 229 260 Total herbivore s with eggs 1510 485 316 20.0 289 240 615 470 Total herbivores (no eggs) 26.0 404 29.6 160 6.2 170 333 .. 370 Stems with Herbivor 680 545 510 60.0 39.2 260 573 520 44

2003 STUDY DISCUSSION OF RESULTS The hypothesis represented by Figure 10 was partially confirmed and the confirmed results are summarized by Figure 11.

• Lepomis spp. t • Lepomis SPP.•

• Acentria • Acentria t ephemerella • ephemerella

• Myriophyllum • MyriOPhYllum. spicatum t spicatum

I------,------~-----=--~...,...,------~ Figure 11. Confirmed model (refinement of Figure 9) illustrating statistically significant trophic relationships between Lepomis macrochirus and L. gibbosus and the Acentria ephemerella, and Myriophyllum spicatum as calculated from 2003 Madison County lakes data.

My 2003 principal results provide an explanation for the lack of success experienced in augmenting Lebanon Reservoir's A. ephemerella population in 2001: Lepomis gibbosus and L. macrochirus prevented A. ephemerella population from expanding.. The data indicate that L. macrochirus have a greater influence on A. ephemerella than L. gibbosus, but that both control A. ephemerella populations. I attribute this to L. macrochirus' willingness to ingest plant material with the insects while L. gibbosus will avoid ingesting the plants. This is consistent with Mittelbach (1988) who concluded that L. macrochirus and L. gibbosus compete for the many of the same foods even while I note their morphological adaptations for different prey (Wemeretal., 1977).

The lack of significance in regressions made with E. lecontei and Lepomis spp. was anticipated. In establishing my sampling protocol with a focus on the 3 m depth contour, I understood that sampling locations were a considerable distance from shorelines necessary for E. lecontei overwintering (Creed & Sheldon, 1994; Jester, et al., 2000, Lillie, 2000; Johnson & Blossey, 2002; Tamayo, 2003). More research is 45 required to detennine if establishing a sampling protocol at some shallower depth might identify a relationship between E. lecontei and fish in these lakes.

The lack of significance in regards to C. myriophylli and any fish is less easily explained. Difficulty in correct identification ofthis chironomid is the likely cause although there may be no relationship. Quality checks on stem sample examinations identified far more incorrect identifications of C. myriophylli than of the A. ephemerella or E. lecontei.

Infonnal consideration had previously been given to the use of Sander vitreus (Mitchill) (walleye; = Stizostedion vitreum) (Percifonnes:Percidae) to control Lepomis spp. However, keeping in mind that not all top-end predators are suited for control ofLepomis spp., I reviewed data from NY State lakes stocked with S. vitreus which revealed that some ofthose stocked lakes had even greater numbers of Lepomis spp. than Lebanon Reservoir (Brooking et al., 2001; Lord, 2003).

The four lakes of the Madison County eight with the least M. spicatum all have S. vitreus and no or few young-of-the-year Lepomis spp. Sander vitreus, a cool water fish, is not well accounted for by electrofishing since they can be located anywhere in a lake when it is electrofished and may not be subject to the electric field used. Seeking to better understand the populations ofS. vitreus, I gathered and examined stocking records for the four lakes. Only Eaton Brook Reservoir is stocked by the NYSDEC. It was stocked at higher than the standard NYSDEC rate (50/hectare [Bishop, 2003]) over the last twelve years (Table 13) as part of a Cornell Biological Field Station experiment (Anonymous, undated; Brooking, 2003; Robbins, 2003). Additionally, it has been detennined that there is some natural reproduction in Eaton Brook Reservoir (Brooking, 2003). Hatch Lake and Bradley Brook Reservoir were each stocked with 1000 15.4 -17.9 cm S. vitreus fingerlings in late 2001 (Crawford, 2003; Walker, 2003) and Tuscarora Reservoir has been stocked each year with the proceeds from its winter ice fishing carnival (Steinbach, 2003). Table 14 summarizes recent S. vitreus stocking in Tuscarora Reservoir. Table 15 provides standard NYSDEC S. vitreus stocking rates for the four lakes and the rates stocked. Stocking rates are less than or equal to the recommended rates for the three privately stocked lakes, but the autumn stockings provide greater survivability for the S. vitreus (Brooking, et al., 2001). Sander vitreus control of insect eating fish in these lakes appears attributable to the autumn stockings. My new hypothetical model (Figure 12) summarizes the understood trophic connection. 46

Table 13. Sander vitreus stockings in Eaton Brook Reservoir 1993 - 2003. 1 Data from Brooking (2003). 2 Data from Anonymous (undated); month of year estimated from the size of S. vitreus stocked. Date Size # ofS. vitreus

I Early May 1991 Fry 1,272,565 1 Early July 1991 5.13 em 5,150 1 Mid Sep 1991 10.26 em 5,150 I Early May 1992 Fry 1,272,565 I Early July 1992 5.13 em 5,150 I Mid Sep 1992 10.26 em 5,150 1 Early May 1993 Fry 1,272,565 1 Early July 1993 5.13 em 5,150 I Mid Sep 1993 10.26 em 5,150 Early May 1994 Fry 1,272,565 1 I Early July 1994 5.13 em 5,150 1 Mid Sep 1994 10.26 em 5,150 Early May 1995 Fry 1,272,565 1 I Early July 1995 5.13 em 5,150 I Mid Sep 1995 10.26 em 5,150 1 Early May 1996 Fry 1,272,565 I Early July 1996 5.13 em 5,150 1 Mid Sep 1996 10.26 em 5,150 Early May 1997 1.28 em 1,270,000 2 Early May 1998 1.28 em 1,270,000 2 1999 NA 0 2 Early May 2000 1.28 em 1,270,000 2 Early May 2001 1.28 em 1,270,000 2 Early May 2002 1.28 em 1,270,000 2 Mid Sep 2002 10.26 em 5,000 2

Average total # S. vitreus stocked each year: 1,171,016 Average # S. vitreus fingerlings stocked each year: 5,567 47

Table 14. Sander vitreus stockings in Tuscarora Reservoir 1993 - 2003. Data from Steinbach (2003). Date Size # ofS. vi/reus

10/21/2002 10.3-15.4 cm 3,000 10118/2001 10.3-15.4 cm 3,000 10/14/2000 10.3-15.4 cm 3,000 10/1611999 10.3-15.4 cm 3,000 10/24/1998 10.3-15.4 cm 2,500 10/2011997 10.3 cm 2,900 10/811996 15.4-20.5 cm 1,000 10.3 cm 600 10/29/1995 10.3-15.4 cm 500 1011011994 10.3-15.4 cm 2,000 10/2711993 12.8-17.9 cm 2,300

Average # S. vi/reus stocked each year: 2,380

Table 15. New York State Department of Environmental Conservation maximum stocking rate for June Sander vi/reus fingerlings compared to the stocked rates for each of the four Madison County S. vi/reus lakes. Note that the three privately stocked lakes were stocked in autumn with fish larger and more survivable than June fingerlings and that half of the Eaton Brook Reservoir fingerlings were stocked in the autumn. Lake NYSDEC Stocking Rate Stocked Rate

Bradley Brook Reservoir 2800 1000 Eaton Brook Reservoir 5000 5567 + 1,165,449 fry + natural reproduction

Hatch Lake 2700 1000 Tuscarora Reservoir 6400 2380 48

• Sander vitreus t • Sander vitreus l

• Lepomis spp. l • Lepomis spp. t

• Acentria t • Acentria l ephemerella ephemerella

• Myriophyllum l • Myriophyllum t spicatum spicatum

Figure 12. Hypothetical model illustrating understood trophic relationships between Sander vitreus, L. macrochirus and L. gibbosus, milfoil insect herbivores, and Myriophyllum spicatum as perceived from Madison County 2003 lakes data.

Additionally, each of these four S. vitreus lakes has distinctly larger Ambloplites rupestris (Rafinesque) (rock bass; =Cichla aenea = Centrarchus aeneus) (Perciformes:Centrarchidae) populations than the four non S. vitreus stocked lakes. The relationship between L. macrochirus and A. rupestris has been investigated previously (Keast, 1977; Weaver, et al., 1997). In the data, a significant negative regression was identified between the logarithmic transformed L. maerochirus data and the A. rupestris data (Log [L. macrochirus] = 2.63 - 0.01 A. rupestris; P= 0.005; R2 = 75.9). It has been reported thatA. rupestris is associated with unvegetated areas while L. maerochirus is associated with vegetated areas (Keast, 1977; Weaver, et al., 1997) and yet, in my study, A. rupestris were found abundantly in vegetated areas of the two lakes with no L. maerochirus (Hatch Lake and Bradley Brook Reservoir) suggesting a niche shift (Smith, 1996) with these two species. A positive, but weak trend exists betweenA. rupestris and theA. ephemerella (A. ephemerella [no eggs] = 3.80 + 0.01 A. rupestris; P =0.243; R2 = 21.9 %).

The negative regressions between M. spicatum and logarithmic transformed A. ephemerella data may be even stronger than it appears. In lakes with few or no M. spicatum "beds, lanes or patches" (Tamayo, 2003), insect herbivores ofM. spicatum find it difficult to locate M. spicatum and likely experience increased mortality in the search. Note that the lake with the least M. spicatum stems at 3 m also had low numbers ofA. ephemerella (Table 12) breaking the trend established with the rest of the data. That lake was Eaton Brook Reservoir which was unique among the eight lakes in that it had no "beds, lanes or patches" of M. spicatum. Removing this 49

minimal M. spicatum lake from the dataset produces a stronger negative regression (M. spicatum stems at 3 m = 260.5 - 217.4 Log A. ephemerella [no eggs]; P = 0.002; 2 R = 87.1).

Sampling at the 3 m depth was undertaken to standardize sampling at a depth where M spicatum grows most densely (Hartleb, et al., 1993). While that guideline applied to most ofthe surveyed lakes, it was not true of Lower Leland Pond where most macrophytes were found in 2.5 m and shallower depths. This was probably due to the limited transparency and the unique water chemistry (brown water; basic pH) ofthe lake. Similar surveys in the future should consider surveying between the 6 foot and 3 m depths.

The regression equations in Table 10 invite consideration of a shortcut for tedious aquatic macrophyte biomass processing. While it is intuitive that density of milfoil stems should regress with milfoil dominance, the strength of this regression was unexpected.

The M. spicatum stem density at 3m positive regression with L. macrochirus (Table 13) is consistent with earlier studies concerning L. macrochirus in the presence ofMicropterus salmoides (largemouth bass) (Gotceitas & Colgan, 1987; Hayse & Wissing 1996).

Eaton Brook Reservoir has previously supported several sizeable beds ofM. spicatum (Harman et al., 2001; Lord & Conde, 2002). Prior to the 2000 survey, anecdotal reports (Burmaster, 2000) indicate that the beds were larger and more numerous. The relationships described herein appear to be responsible for the turn­ around in Eaton Brook Reservoir's aquatic plant community.

RECOMMENDATIONS FOR FUTURE RESEARCH

The eight lakes studied in 2003 provided insight into the dynamics ofM. spicatum herbivory, insectivory on M. spicatum herbivores, and predation on the insectivores. However, only four lakes contained S. vitreus and sampling ofwalleye was not comprehensive. We need to determine if introductions of S. vitreus can facilitate the reverse ofL. macrochirus and M. spicatum dominances as portrayed in Figure 12. Previous work investigating L. macrochirus control with S. vitreus provided marginal results, but, in that case, S. vitreus were stocked at 37-45 per hectare (Schneider & Lockwood, 2002) which is less than the New York State stocking recommendation. I recommend a full lake experiment introducing significantly greater numbers ofS. vitreus into Lebanon Reservoir with follow-up monitoring for three years. Additionally, a series of replicated pond experiments should be undertaken to verify the apparent associations identified in this study. 50

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APPENDIX A: Identification of herbivory on Myriophyllum spicatum (Eurasian water-milfoil) stem samples.

Procedure

1) This procedure is abbreviated; use it with reference to descriptions for M spicatum parts and insect life stages that follow it. 2) Note location, dates, stem collector and herbivore identifier on data sheet. 3) Pick up stem and examine carefully from basal end to growing end. a) Look for aberrations in the normal sequence of longer to shorter internodal lengths examining leaves carefully in such areas. b) Look for numbers of missing leaves and any cut or missing dissected veins. c) Examine growing apical meristems. d) Make notes on condition of stem and meristems, and, under "Comments" make notes regarding % of sample covered by algae and/or precipitate. 4) Place stem on microscope stage and examine carefully from basal end to growing end. a) Pull apart leaves and/or dissected veins giving the appearance ofbeing stuck together. b) Pull apart any brown areas on the stem with dissecting probes 5) Examine plastic bag, in which stem was stored, for herbivores. 6) Make notes on the condition ofthe leaves and note any animals present. 7) Return stem to the plastic storage bag along with all herbivores not jarred for confirmation and note completion of examination on bag.

Myriophyllum spicatum Plant Parts

Stem

Internodal lengths not consistently shorter going from basal end to apical meristem: herbivore damage at shorter internode (Kangasniemi, 1983; Johnson, 2000b).

Mined (hollowed, often brownish in color) for a length> 0.5 cm; often with obvious exit and entry holes: Euhrychiopsis lecontei damage (Kangasniemi, 1983).

Saddle or scoop shaped scar approximately as long as the stem is wide: Adult Euhrychiopsis lecontei damage (Johnson, 2000b).

Irregular scar with a leaf or leaves twisted/wrapped around the area: Acentria ephemerella larva damage. 68

Leaf

Leaf dissected veins cut at midpoint in length: Cricotopus myriophylli damage (Johnson, 2000b).

Leaf dissected veins cut at midvein: Acentria ephemerella larva damage (Johnson, 2000b).

Apical meristem

Twisted, nonsymmetrical, and not fully leaved: likely herbivore damage.

Case made with dissected veins and silk (i.e., a "refuge" or "retreat") on apical meristem or close to it:

More or less parallel orientation of dissected veins used in refuge: Acentria ephemerella

More or less random orientation of dissected veins used in refuge: Cricotopus myriophylli.

Insect Life Stages

Adult

Adult weevils 2 - 3mm long with black & yellow stripes on the dorsal side and a lighter greenish yellow ventral side: Euhrydziopsis lecontei (Jester, 1998).

Moth with wings not capable of flight: female Acentria ephemerella (Batra, 1977).

Larvae

Larvae with obvious gills: not a known Myriophyllum spicatum herbivore.

Larvae with five pairs of prolegs (moth larva; "caterpillar") with sceloritized plates on head and closed spiracles with no gills: Acentria ephemerella (Batra, 1977; Albright, 2000).

Larvae with no true legs found inside stem or adjacent to mining; brown or grey in color; head color noticeably darker than body with beak-like protrusion on front: Euhrychiopsis lecontei (Miller, 2000; Miroiu, 2003).

Chironomid larvae < or = 0.5 em, translucent cream colored, with guts in helical configuration (twisted like Spirogyra spp.); possessing fine lateral setae with one (and only one) bundle of setae (not a singular seta) on each segment and indistinct segmentation: Cricotopus myriophylli (Johnson, 2000b; MacRae, 2001; Oliver, 69

1984). Frozen specimens do not display the characteristic helical gut configuration and appear translucent cream colored. Distinguishing from similar appearing local chironomids: Nanocladius spp. have a "very lightly pigmented median portion of the mentum with two little points ("nipples") in the middle." Psectrocladius spp. have "palmate SI setae and two large, brown median teeth" (Berg, 2002). Typically found in a "retreat" formed of dissected veins with dissected veins nearby grazed which differentiates it from other Cricotopus spp. which form "retreats" but do not graze M. spicatum (MacRae, 2001).

Eggs

Cream colored with brown spots on thin coating which is otherwise clear; elliptical (shaped like grains of rice); ~ 0.5mm x 0.4 mm (or ~1/3 the size of rice grains); typically one or two on or in apical meristem or on leaves of the node just beneath it: Euhrychiopsis lecontei (Creed and Sheldon, 1995; Sheldon, 1997b; Jester, 1998; Johnson, 2000b).

Yellowish-orange clusters of round eggs around a dissected vein typically found about 25 to 50 cm down stem from growing tip: Acentria ephemerella (Johnson, 2000b; Miller, 2000).