Area covered: Herbicide Treatment area from Rte 79 bridge to the south up to the Allan Treman Marina Boat Launch

Transcription

1 Hydrilla Survey Report 7 November 2011 Compiled by Holly Menninger, PhD Area covered: Herbicide reatment area from Rte 79 bridge to the south up to the Allan reman Marina Boat Launch Survey crews: Boat: om Hughes (State Parks), Bob Johnson, Holly Menninger (Cornell NYISRI), Cassie Garcia (Cornell student) By shore: Lynn Bogan (State Parks), Kristen Cady-Sawyer (State Parks) Methodology: As in previous surveys, Johnson overlaid 50 m x 50 m UM grid lines on the Inlet map. he Boat Crew sampled with 2 rake tosses at points where the North and East grid lines crossed. Given time constraints, we were unable to select all intersect points, but chose places that 1) had high density of hydrilla in previous surveys and 2) represented different habitat types in the Inlet. Additionally, we collected samples at a few other locations, not located on intersect points, and recorded their UM coordinates. We used NAD 1983 Datum and rue N. A total of 29 points were surveyed by boat, and hydrilla was collected at 12 of those locations. he Shore-based Crew surveyed 14 points on the edges and off the docks of Allan reman Marine Park. Additionally, they sampled 5 points along the western shore of the Inlet from the Dragon Boat Docks down to the south shore at the mouth of Linderman Creek. All hydrilla stems and fragments collected during the survey were placed into labeled bags, locations noted, and then saved for further inspection in the lab. General observations: Generally, the quantity of hydrilla biomass seems to have declined significantly since pre-herbicide surveys. his is particularly noticeable in Cascadilla Creek where the sediment is largely devoid of vegetation; patches of hydrilla that remain are lying on the bottom sediment and look unhealthy but are alive. We did collect one small fragment from this area that appeared to have a turion (Figure 4); no other turions were noted during sampling. Despite the decline in the overall quantity of biomass in densely infested areas, we frequently detected plants growing new shoots and some areas with surface cover by hydrilla. In fact, in areas near the Cornell Crew boathouse and the NYS DO facility (east shore of Inlet, south of Farmers Market), hydrilla plants looked rather robust and thriving (Figures 1-3). he observation of green shoots and apical buds were not isolated to this area; all points sampled along the west shore of the Inlet from the Dragon Boat Docks to the south shore of Linderman Creek had hydrilla with green shoots as did a single plant fragment collected near the reman boat launch (it had multiple green buds, Figure 5). he question remains why these plant fragments appear unaffected by the herbicide treatment Were new buds not susceptible to the treatment? Were treatment concentrations too low to be effective in very densely infested areas?

2 Specific findings: Note Rake oss Average Density reported below is based on the aquatic plant density scale routinely employed for aquatic plant surveys in NYS: Abundance (Field code) Field Measure Biomass (dry weight; g m- 2 ) No plants (Z) No Plants 0 race Plants () Fingerful (1-2 stems) Up to 2 Sparse Plants (S) Handful (3-6 stems) 2 to 140 Medium Plants (M) Rakeful (not tines visible) 140 to 230 Dense Plants (D) Difficult brining weed mass into boat 230 to >450 Sample ID UM Coordinates Findings Additional comments Rake-toss Avg Bob, Holly, om and Cassie Boat crew Mud, * Mud, small amounts of water stargrass Mud, leaves No aquatic vegetation Mud, leaves No aquatic vegetation Mud, leaves No aquatic vegetation Mud Leaves Mud, leaves No aquatic vegetation Hydrilla with green new shoots Visual observations from boat: Hydrilla plants lying on Inlet bottom near Island Fitness shore Near Boatyard Restaurant docks Just south of CU boathouse, small indent near shore Outside of treatment area? Mud, Inlet near CU Crew floating docks Healthy looking hydrilla (green) fragments; rooted fragments with new green shoots Within CU Crew floating docks

3 Hydrilla with lots of new leaf & stem shoots, but not as much biomass as earlier in the season (some evidence of decay) Green and growing hydrilla fragments, new growth from treated material with new expanding shoots A green hydrilla fragment collected from bottom sediment Robust, green hydrilla plants with new shoots A few small hydrilla fragments (with a few shoots) plants look worse than other locations, but all alive A few small hydrilla fragments with new green shoots Small, sick looking but alive hydrilla fragments (1 with turion) A few small fragments that look bad but alive, not obvious new green shoots Rooted hydrilla fragments with green shoots Lots of floating hydrilla fragments in the water behind the boat; Hydrilla is not decaying mush but healthy alive plants Hydrilla plants notably lying on bottom; Large mass of hydrilla removed (pic) all green when washed Where ducks/geese previously seen feeding Floating hydrilla fragments Middle of Inlet channel near DO Approaching Farmers Market In middle of Farmers Market dock slips (south side) Cascadilla Creek Most of the bottom appears bare, with remaining plants lying down on sediment In middle of Cascadilla Creek, adjacent to Johnson s Boatyard covered slips Near Dragon Boat docks medium Near reman boat launch 1 hydrilla fragment in sediment with multiple green buds North of reman launch; hydrilla fragments floating in water Lynn & Kristen, Shore Crew 25% lush green, all alive Dragon boat launch, many fragments 5% lush green shoots, all alive South of Dragon Launch 5% lush green shoots, all alive 10 fragments % lush green shoots, all alive Linderman Inlet Mouth, north side location tossed to Cayuga Inlet 25% lush green shoots, all alive Linderman Inlet Mouth, south side location tossed to Cayuga Inlet medium

4 One fragment, alive but no new shoots No roots

5 Images from Boat Crew Survey Figure 1: Large mass and closeup of green shoots collected near DO facility (Survey Pt #19) Figure 2: Rake samples near Cornell Crew embayment (First 1 st & 2nd photos: Survey Pt #16, 3 rd photo: Survey Pt #17)

6 Figure 3: ypical hydrilla sample where robust green shoots emerging from somewhat affected plants

7 Figure 4: Small sickly hydrilla fragment collected in Cascadilla Creek with turion. (Sample Pt. #22) Figure 5: Fragment collected from the sediment north of reman launch with multiple healthy green buds (Sample Pt. #28)

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9 Conclusions We observed significant, 90 95% decline in the total biomass of hydrilla in the treated area of the Cayuga Inlet. Some areas of the Inlet that were densely infested with hydrilla, particularly the portion of Cascadilla Creek near the Ithaca Farmers Market, showed remarkable decreases in hydrilla coverage. Additionally, we observed only one turion in 48 samples collected, and that turion was detected on a damaged and decaying plant fragment collected near the mouth of Cascadilla Creek. hus, we successfully accomplished the two desired outcomes for the October Aquathol K treatment: 1. Remove hydrilla biomass to reduce potential for further spread 2. Prevent hydrilla plants growing in the treatment area from producing turions Despite the significant declines in total hydrilla biomass, there remain treated areas of the Cayuga Inlet with viable stems and fragments of hydrilla. Survey crews collected hydrilla fragments (many with live and actively growing green shoots) at 18 locations throughout the Inlet. In these locations, stem density was typically fewer than 6 stems. he Hydrilla ask Force anticipated that the Aquathol K treatment would result in significant, but not complete control of hydrilla in the treatment area. he results that we observed including significant biomass decline, accompanied by some delayed die-off and the initiation of new shoots are consistent with observations from other water bodies in the Northeast where Aquathol K has been previously used to control other invasive aquatic plants (e.g., Eurasian watermilfoil). he data we collected during post-treatment monitoring will provide important information about how hydrilla responds to endothall treatment late in the growing season, information that was previously lacking for the Northeast. Moreover, the results we report here will be used to inform follow-up management actions next spring. Early in the process, the Hydrilla ask Force acknowledged that the hydrilla management effort would be a multi-year endeavor. he October Aquathol K treatment was an important first step towards the long-term goal of eradication.

10 Post reatment Hydrilla Monitoring Results Boat and Shoreline Rake osses GA YU CA LA KE C AC SR ES D OA S RK PA R A W E RD November 7, PI E RR D RA NC E 27 RK S PA CAS EN 26 R PIE HA NN OCK BLVD H 19 IR D ME AD OW EA DO W 15 NM CIR 10 1 F LO EL M RA LA VE medium ± :6,000 1,000 Feet W BUFFALO N NR MO OE PARK PL WASHINGON CASCADILLA N MEADOW 2 MA ON DIS N CORN 3 N FULON 4 PARK R D CHEN U AYLOR PL Rake oss Average O UL NF ALLEN S AUGHANNOCK BLVD 5 E AV H RD IS RR UR FO 6 7 HS Legend UNRISE L MO FIF 9 HOP PER P HA KS OC C N H 11 ND CO SE 13 UR FO 12 CA R OR HEC 14 D IR PE N ER H 17 IN S 16 8 FR KL AN S FIR CASS PA RK A 18 ROAD N PLAIN AU G F CLIF VINE G AR 20 VE WA LO WIL VE EA AVE LL PBE ESS CC 22 K LA M CA LL HI 21 YS DE L RP LO Y A E AV OW LL WI 32 N R E R UN D MO ES IEW W V FALL N RD NY State Plane, Central GRS 80 Datum Map Source: ompkins County Digital Planimetric Map Data Source: City of Ithaca Department of Public Works, 2008 Map Prepared by: GIS Program, City of Ithaca, NY, November, 2011