Impact of Nitellopsis obtusa (Desv.) J. Groves, a regionally alien and invasive charophyte, on macrophyte diversity in the species native range

Abstract

This study aimed to determine the relationships between the abundance of Nitellopsis obtusa, a controversial charophyte, locally red-listed in its native Eurasian range but invasive in North America, and the species diversity of macrophyte stands dominated by N. obtusa. Three lakes of different morphology, productivity and catchment were surveyed in the species native range. In each lake, the species composition and cover of three N. obtusa-dominated stands were determined monthly from spring to autumn and illustrated by the Shannon–Wiener diversity index. Water chemistry supplemented vegetation study. The species diversity turned out to be lake-specific and declined with the increasing share of N. obtusa, which developed mass occurrence in less mineralised and less fertile waters, leaving no space and limiting light and nutrient availability for large and branchy macrophytes. We postulate that this mechanism makes N. obtusa a superior competitor in less fertile waters and seems common to both native and invaded territories, as is the pool of macrophyte species most frequently co-occurring with N. obtusa.

Pervasive changes to the lower aquatic food web following Nitellopsis obtusa establishment in a large, shallow lake

“…Brainard and Schulz (2017) found that native and non-native macrophyte richness declined in central New York State lakes where N. obtusa was present, and Ginn et al ( 2021) documented reduced biomass of macrophytes coinciding with the colonisation and establishment of N. obtusa in Lake Simcoe. A recent study of N. obtusa in its native range also showed a negative effect on macrophyte diversity with increasing N. obtusa dominance (Pełechaty et al, 2021).…”

“…(2021) documented reduced biomass of macrophytes coinciding with the colonisation and establishment of N. obtusa in Lake Simcoe. A recent study of N. obtusa in its native range also showed a negative effect on macrophyte diversity with increasing N. obtusa dominance (Pełechaty et al., 2021). There are likely to be several mechanisms by which N. obtusa displaces other macrophyte species.…”

“…As more studies are published, it is becoming apparent that N. obtusa can alter habitat structure and function, as well as displace other macroalgae and vascular macrophytes (Brainard & Schulz, 2017;Ginn et al, 2021;Harrow-Lyle & Kirkwood, 2021b;Pełechaty et al, 2021;Pullman & Crawford, 2010). Despite N. obtusa being a non-native invasive species in North America, it is often regarded as an important component to shallow lake dynamics within its native range (Christensen et al, 2013;Kufel & Ozimek, 1994;Van Den Berg et al, 1998).…”

“…Despite N. obtusa being a non-native invasive species in North America, it is often regarded as an important component to shallow lake dynamics within its native range (Christensen et al, 2013;Kufel & Ozimek, 1994;Van Den Berg et al, 1998). In spite of N. obtusa being classified as a threatened to critically endangered species throughout most of its native range (Auderset Joye & Schwarzer, 2012;Blaženčić et al, 2006;Kato et al, 2014;Korsch et al, 2013), Pełechaty et al (2021) have recently shown that when N. obtusa increases in dominance in lakes of its native range, macrophyte diversity declines. Thus, our results may not just reflect the effects of N. obtusa invasion in its non-native range, but reflect potential effects in any aquatic ecosystems it becomes the dominant macrophyte.…”

Distribution pattern of <i>Nitellopsis obtusa</i> (Desv.) J.Groves (<i>Charophyta</i>, <i>Charales</i>) in Ukraine

“…Прикладом типових місцезростань N. obtusa є великі глибокі вулканічні озера (Віко, Болсена, Браччанно, Лаціо, Немі та ін.) в Італії (Azzella, 2014), озера Балканського п-ва (глибоке Шкодра та мілководне Преспа) (Blazencic et al, 2006), Південного Уралу (Велике Міасове, Єлове) (Veisberg, Isakova, 2010), Польщі (Pelechaty et al, 2022), Литви (глибоке Дуся, мілководне заболочене Жувінтас) (Sinkeviciene, 2007), водойми в авандельті Волги (Zhuvogliad, Krivonosov, 1982) тощо. За оптимальних умов зростання вид здатен формувати довготривалі щільні моно-або маловидові зарості та конкурувати з деякими видами Charales, наприклад з C. aspera та C. contraria, і представниками судинних водних рослин (Azzella, 2014;Pelechaty et al, 2022).…”