2011 SURVEY OF AQUATIC PLANTS ON THE BEAR LAKES
On 12 January 12 2011, Seminole County Lake Management Program (SCLMP) staff Marie Lackey, Dean G. Barber, and Thomas Calhoun surveyed the aquatic plants of Bear Lake. Submersed aquatic vegetation (SAV) observed include: southern naiad to a depth of 4 feet, stonewort to 7 feet and eelgrass to 18 feet. Eelgrass was established in dense monoculture populations reaching almost to the surface from depths of 10 feet, and then extending to a depth of 18 feet, continuing to be the dominant SAV of both submersed and emergent aquatic plants. With this depth capability, eelgrass was the most prevalent throughout the lake, except for the northeast to southeast where stonewort and southern naiad is established out to 7 feet. This eelgrass coverage represents over 60% of the lake’s sub-surface, such that, with wave and wind action most of the broken off fragments found adjacent to the shore was eelgrass. The plant was healthier than previously observed as it is not as covered with filamentous algae as has been reported on previous surveys. With the populations of stonewort and southern naiad being impacted by the triploid grass carp fish, which have also reduced or eliminated other previously observed native SAV like chara, possibly road grass and the invasive exotic hydrilla, this could provide an opportunity for eelgrass to expand into new habitat.
Pictured left: Southern Naiad found mixed in with eelgrass
The invasive exotic torpedo grass continues to be the most abundant emergent aquatic plant, which was adjacent to most waterfronts. Even though torpedo grass was the dominant emergent, it has been impacted, as the other emergent plants, by the winter cold weather. All of these aquatic plants will recover and expand in the warmer spring months. Few water hyacinths were observed in the Linneal Beach Drive canal and none were noted in the lake.
The lake elevation was 102.7 feet above sea level compared to 102.89 feet on the previous survey. Secchi depth was 13.6 feet in a depth of 19.8 feet compared to 10.4 feet on the previous survey.
This information and much more can be obtained on the Seminole County Watershed Atlas at: http://www.seminole.wateratlas.usf.edu/lake/?wbodyatlas=lake&wbodyid=7514.
2010SURVEY OF AQUATIC PLANTS ON THE BEAR LAKES
On 23 February 2010, Seminole County Lake Management Program staff Gloria Eby, Dean G. Barber (Consultant), Thomas Calhoun (Assistant Scientist) with lake resident Bob Shields surveyed the aquatic plants in Little Bear Lake. One sprig of the submersed aquatic vegetation (SAV) musk grass was found, the first SAV observed in the lake since these surveys have begun almost a year ago. Additionally, the amount of planktonic algae in the water column was significantly reduced from the previous survey, 1 October 2009, whereas the secchi (water clarity) reading was 12.2 feet in a depth of 18.7 feet compared to 2.9 ft. in 5.5 ft, a remarkable improvement! Also the filamentous algae population was reduced from the last survey. All the emergent aquatic plants, both exotic and native, have been impacted by the cold weather, but will become more apparent and begin to expand as spring approaches. The lake elevation was 102.79 feet above sea level.
On 23 February 2010, Seminole County Water Lake Management Program staff Gloria Eby, Thomas Calhoun (Assistant Scientist), Dean G. Barber (Consultant) and Ryan Hamm (FWC Biologist) surveyed the aquatic plants in Bear Lake. This is the first month since 14 May 2009 that hydrilla was not observed on the survey, even though we went to two previously (GPS) documented hydrilla locations and made several other bottom grabs. However, the two surveys before the May 2009 survey, 27 January 2009 and 18 November 2008, hydrilla was observed and all the surveys between 14 May 2009 to present. On all of the previous surveys that hydrilla was observed, it was present in both areas; inshore and offshore. The inshore population has always competed for space with the native SAV, dominantly eelgrass and stonewort, with smaller populations of chara, road grass, baby tears and southern naiad. Offshore hydrilla has competed with mostly eelgrass with also in competition with chara, southern naiad and stonewort. The alarming concern offshore is that the hydrilla can receive enough light in deeper water, documented to depths over 20 feet, than the native SAV, usually to 15 feet, thereby, hydrilla is establishing and spreading into these deeper zones. However, presently it was not observed in any of these sites. The true test will be in the spring when all plants will be actively growing, to see if hydrilla will be included. Also apparent is that the native SAV population is presently not declining or expanding, but also, waiting for spring.
The emergent aquatic plant populations were the most obviously impacted from the winter dieback, such that it was difficult to discern between the exotic grass torpedo grass and the native maidencane, although, both are present. Like the SAV, these populations will be expanding in the spring. Water hyacinth were still observed in the canal off of Linneal Beach Drive, but none were found in the lake. The two species of the exotic papyrus (Cyperus papyrus) and dwarf papyrus (Cyperus papyrus or C. isocladus) are still a dominant factor in the canal. The water elevation was 103.88 feet above sea level.
On 23 February 2010, Seminole County Water Lake Management Program staff Gloria Eby, Thomas Calhoun (Assistant Scientist), Dean G. Barber (Consultant) and Ryan Hamm (FWC Biologist), surveyed the aquatic plants in Cub Lake. All aquatic vegetation acreage, whether submersed or emergent was reduced from winter dieback. Submersed aquatic vegetation (SAV) was further below the waters surface because of the colder weather, with some species not being observed at all. Neither, musk grass nor southern naiad were observed, however, both of these native SAV have been present during past surveys. As much as all of these aquatic species have been impacted, all will be present in the spring. Stonewort continues to be the dominant SAV, closely followed by the native eelgrass, then bladderwort (Utricularia radiate), all still present to 7-9 feet. We did walk the ditch south of Cub Lake Drive and found the invasive exotic hydrilla in two locations within the canal, the closest within 100 feet of the lake.
The most abundant exotic emergent aquatic plant is torpedo grass, followed by the invasive native, cattails. Both significantly impacted by the colder weather, and both will return strongly in the spring. The two native lilies, spatterdock and fragrant water lily, were observed to a depth of 13 feet. Other invasive plants/trees observed included: wild taro, also called elephant ear, papyrus grass (Cyperus papyrus), Chinese tallow and Brazilian pepper. The secchi reading (water clarity) was 14.9 feet in a depth of 15.5 feet, improved from the previous month of 14.5 ft. Water elevation was 100.3 feet. This and other lake information is available on the Seminole County Watershed Atlas web site: http://www.seminole.wateratlas.usf.edu/.