Nitellopsis obtusa, Starry Stonewort A Non-Native Submerged Aquatic Lower Plant STARRY STONEWORT (SSW) Nitellopsis obtusa • Some information provided in this power point presentation comes from the following source: HACKETT, R. A., CARON, J. J., & A. F. MONFILS. 2014. Status and Strategy for Starry Stonewort [Nitellopsis obtusa (N. A. Desvaux) J. Groves] Management. Michigan Department of Environmental Quality, Lansing, Michigan. STARRY STONEWORT (SSW) Nitellopsis obtusa General Characteristics • SSW is a nonindigenous submerged aquatic lower plant. • SSW is a summer annual, but can overwinter as a perennial during mild winters. However, SSW in Michigan appears to thrive in the cooler waters of fall, winter, & spring, & become dormant or less active during hottest parts of summer (Pullman & Crawford 2010) • SSW is a member of the Characeae plant family. Complete taxonomic classification will be presented. • SSW is a filamentous alga. It has straight branches arranged in whorls of 4 to 6 long branchlets, and attached at acute angles to stem nodes. STARRY STONEWORT (SSW) Nitellopsis obtusa General Characteristics • Most stem & branch cells are around 1 mm in diameter, and stems can extend up to 80 cm long, or 31.5 inches (Hargeby 1990). Growth up to 2 meters (6.5 ft) has been observed at a depth of 9 m (29.5 ft) in one Michigan Lake (Pullman and Crawford, 2010). Source: www.seagrant.sunysb.edu. SSW STARRY STONEWORT (SSW) Nitellopsis obtusa General Characteristics • The “squeeze test” may be used to distinguish SSW from Chara spp. In SSW, the protoplasm will pop out of the cell when squeezed. The remaining cell wall becomes limp straw (G. Douglas Pullman, Aquest Corp, personal communication). In Chara spp., the protoplasm does not separate easily from the cell wall (Hackett et al. 2014). STARRY STONEWORT (SSW) Nitellopsis obtusa General Characteristics • SSW has colorless hair-like filaments called rhizoids that act like roots. The rhizoids attach the plant to an aquatic bottom, but they frequently detach from an aquatic bottom to form a floating mat. • Stoneworts have ability to absorb nutrients through all surfaces, not just the rhizoids. • SSW can be found at depths of 3-20 feet in lakes or slow moving rivers. STARRY STONEWORT (SSW) Nitellopsis obtusa General Characteristics • SSW plants can form gyrogonites, which are calcified, spiral-shaped fructifications (Bharathan 1983, 1987). Another definition from the online plain text English dictionary is the petrified fruit of Chara hispida, a species of stonewort. Source: www.researchgate.net, shows SEM lateral & apical views of gyrogonites of Chara aspera (figs. 1-2); C. hispida (figs. 3-4); & C. globularis (figs. 5-6). STARRY STONEWORT (SSW) Taxonomic Classification • EMPIRE…………………………………………….…Eukaryota • KINGDOM…………………………………………....Plantae • PHYLUM…………………………………………..... Charophyta • CLASS……………………………………….………Charophyceae • ORDER………………………………………………Charales • FAMILY………………………………………………Characeae • GENUS……………………………………………….Nitellopsis* • SPECIES…………………………………………….obtusa *Other genera in Characeae family are Chara, Lamprothamnium Lynchnothamnus, Nitella, & Tolypella. Source: Lewis & McCount (2004) STARRY STONEWORT (SSW) Nitellopsis obtusa General Life Cycle • SSW plants are dioecious. • SSW has orange female structures called oogonia that are located in the nodes of upper branchlets. • Dark red to orange-colored oospores are female gametocytes and occur at the nodes of branches. Source: www.wolverinelake.com. A decade of starry stonewort in Michigan ( Pullman, G. D. & G. C. Crawford, 2010). Note dark red-colored oospores. They are female gametocytes from which an egg develops. STARRY STONEWORT (SSW) Nitellopsis obtusa General Life Cycle • In sexual reproduction, plasmogamy (fusion of haploid gametes) is followed by karyogamy (nuclear fusion) to form a diploid zygote (Graham, L. E., & L. W. Wilcox. 1999). • Sexual reproduction in SSW occurs through production & fertilization of oospores. Mature oospores usually are produced only under eutrophic conditions & have a mandatory dormant period before germination (Bharathan 1987; Hackett et al 2014). • Spore production may be controlled by light & tends to take place from July to September. STARRY STONEWORT (SSW) Nitellopsis obtusa General Life Cycle • Asexual reproduction is a means by which an individual organism can produce additional copies of itself without unions of cytoplasmic nuclear materials or meiosis. • One way SSW asexual reproduction occurs is by prolific production of vegetative bulbils. Creamy white bulbils may occur at the base of the main stem just below the substrate water interface, and on branches of the main axis at nodes. STARRY STONEWORT (SSW) Nitellopsis obtusa General Life Cycle • Bulbils stay viable for several years. They can be found at any point during the year, but are most abundant in late fall & early spring (Hackett et al 2014). • Bulbils can sprout in 3-5 days under the right conditions (Bharathan 1987). STARRY STONEWORT (SSW) Nitellopsis obtusa Life Cycle With Zygotic Meiosis Most chlorophyceans & charophytes (includes Chara spp., & Nitellopsis obtusa) are primarily found in freshwaters. These algae have haploid vegetative phases, the zygote is the only diploid stage, & zygotic meiosis occurs. [After L. E. Graham & L. W. Wilcox. 1999.] STARRY STONEWORT (SSW) Nitellopsis obtusa Means of Spread of SSW • SSW can be spread by oocytes. Oocytes could be easily transported in aquatic plant debris caught in boat trailers. Also oocytes can easily become attached to the fur and feathers of aquatic fauna, & is an effective Aquatic plants hitching ride on a boat way for SSW to spread trailer. Michigan Dept. of Environmental rapidly among inland lakes Quality. MSU Extension. Online photo (Pullman & Crawford msue.anr.msu.edu 2010). STARRY STONEWORT (SSW) Nitellopsis obtusa Means of Spread of SSW • SSW is easily fragmented & these fragments may act as disseminules that could be important in the spread of the plant within a lake & from lake to lake. Boat traffic can cause significant fragmentation of SSW that can float on the water surface & create nuisance conditions on leeward shorelines (Pullman & Crawford 2010). STARRY STONEWORT (SSW) Nitellopsis obtusa Means of Spread of SSW • SSW can be spread by star-shaped bulbits that occur mainly on the lower stem nodes near the substrate, reach 4 mm across (0.2 in), & stay viable for several years (Hackett et al 2014). Source: Online photo at www. uwsp.edu SSW bulbits & filamentous branches. Source: www.masoncounty press.com. SSW plants invades Pentwater Lake. STARRY STONEWORT (SSW) Nitellopsis obtusa Means of Spread of SSW • Others vectors that likely are involved in the spread of SSW include aquatic fauna, ballast water, boats, and trailers. SSW was believed to have been introduced in ship ballast water into the St. Lawrence Seaway (Geis 1981; Schloesser 1986). • Little data have been published regarding ideal environmental conditions or nutrient levels that promote invasive SSW growth in lake ecosystems (Brown 2014). Most of what is known comes from observations (Hackett et al 2014). STARRY STONEWORT (SSW) Nitellopsis obtusa Distribution Native Range: SSW is native to Eurasia, from the west coast of Europe to Japan (Mills et al. 1993; Soulie-Narsche et al. 2002). Present: United States range includes much of the Great Lakes Region, & parts of the Upper Mississippi-Crow-Rum Basin, the Rock Basin, the Upper Illinois Basin, the Allegheny Basin, the Upper Susquehanna Basin, & the St. Francois River Basin (U. S. Dept. of the Interior, U. S. Geological Survey. URL:nas.er.usgs.gov.). This website actually lists collection information for 1529 SSW sites in the Great Lakes Region. STARRY STONEWORT (SSW) Nitellopsis obtusa Distribution Present Range in the Great Lakes Region includes: Michigan: 1st found in 1983 at Lake St. Clair, along the Saint Clair & Detroit Rivers (Schloesser et al. 1986). Now occurs at lakes in all Lower Peninsula basins & the Millecoquins Lake of the Upper Peninsula (Pullman & Crawford 2010). Michigan has most reported occurrences of any state. Indiana: Initially discovered in 2008 in Lake Wawasee (Edgell 2011; Aquatic Weed Control 2015). Currently SSW is in 8 lakes in northeastern Indiana (Edgell 2011; Pearson 2015). STARRY STONEWORT (SSW) Nitellopsis obtusa Indiana Distribution (USGS Data) Indiana: Currently SSW is in 10 lakes in northeastern Indiana as follows: Kosciusko Lake Wawasee, Syracuse 2008 Established Kosciusko Syracuse Lake, Syracuse 2011 Established Kosciusko Tippecanoe Lake, Oswego 2013 Established Kosciusko Webster Lake, North Webster 2015 Established LaGrange Adams Lake, Wolcottville 2014 Established LaGrange Wall Lake near town of Orland 2010 Established Steuben Crooked Lake, Angola 2011 Established Steuben Jimmerson Lake, Angola 2012 Established Steuben Lake George at Ind/MI border 2009 Established Steuben Lake Pleasant* 2015 Established *just behind boat launch in end of channel by the marina STARRY STONEWORT (SSW) Nitellopsis obtusa Distribution (USGS Data) NOTE: These data are preliminary or provisional and are subject to revision. They are being provided to meet the need for timely best science. The data have not received final approval by the U. S. Geological Survey (USGS) and are provided on the condition that neither the USGS nor the U. S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the data. STARRY STONEWORT (SSW) Nitellopsis obtusa Distribution Present Range in the Great Lakes