The family Characeae, commonly known as stoneworts, consists of green algae characterized by macroscopic thalli composed of a series of nodes and internodes. These structures are not merely botanical curiosities but play critical ecological roles in their respective environments. Stoneworts contribute to high water transparency, sequester significant amounts of carbon and nutrients, and serve as a foundational element of the aquatic food web. Furthermore, they provide essential habitat and refuge for various aquatic animals. Due to their sensitivity to environmental changes, including salinity, temperature, and water chemistry, Characeae species are widely recognized as effective bioindicators. Their presence or absence can offer valuable insights into the overall health and stability of freshwater and brackish ecosystems.

Despite their ecological importance, many Characeae species are currently facing severe threats to their survival. The combination of continuous human transformation of habitats and ongoing climate change has placed these algae at risk, particularly in arid and semiarid regions. Consequently, numerous species are protected under European directives, such as the Habitats Directive 92/43/EC and the Water Framework Directive 2000/60/EC. In several European countries, national legislation further safeguards these organisms, and they are included in national Red Lists to monitor their conservation status. However, Italy lacks a national Red List for Characeae, representing a significant gap in the country’s conservation framework. This absence hinders the implementation of targeted protection measures and the accurate assessment of population trends across the Italian peninsula and its islands.

The study conducted in spring and summer 2022 focused on sampling sites selected for their visual coverage of Characeae exceeding five percent. The locations included the Laghetto Monte Soro in Cesarò, the Lago Ancipa-Sartori in Troina, the Geloi Wetland in Gela, and the Curcuraggi area in Melilli. These sites varied significantly in altitude and water type, ranging from high-altitude natural lakes within the Nebrodi Regional Natural Park to low-lying brackish marshes fed by saline springs. The Geloi Wetland, for instance, is situated at approximately 30 meters above sea level and features artificial marshes with brackish water resulting from an underground saline spring. In contrast, the Monte Soro lake is located at about 1,575 meters above sea level, an environment where water often freezes during the winter months.

Among the species identified, Chara globularis was found in the Curcuraggi area, a site characterized by temporary pools used by grazing cattle. This species is cosmopolitan in distribution and has been reported from various regions in Italy, including Trentino Alto Adige, Piedmont, and Lombardy. Its presence in an area impacted by human activity is consistent with previous studies indicating that C. globularis is tolerant of eutrophication and anthropogenic disturbances. The morphology of the specimens collected showed thalli between 24 and 30 centimeters tall, with slender rays and rudimentary spine cells. The species is monoecious, bearing both oogonia and antheridia on the same thalli, which facilitates sexual reproduction in stable environments.

Chara vulgaris, another cosmopolitan species, was recorded in the Geloi Wetland and the Lago Ancipa-Sartori. This is the most widespread and frequently reported species of the genus Chara in Italy. The specimens observed had thalli ranging from 10 to 30 centimeters in height, with a main axis diameter of approximately 600 micrometers. The rays were slightly curved upwards, and the cortex was diplostichous and aulacanthous. The presence of C. vulgaris in these previously uninspected sites adds valuable data to its distribution map in Sicily. Conservation status assessments for this species vary across Europe, with classifications ranging from endangered in Norway to least concern in Wales, highlighting the need for localized monitoring and protection strategies.

Nitella capillaris, a less widespread species primarily found in Europe and Africa, was discovered in the Monte Soro Lake in Cesarò. This finding is significant because the species had not been previously reported in the province of Messina. The lake’s high altitude and cold climate pose unique challenges for algal survival. However, N. capillaris is known for its ability to withstand frost, producing oospores that are resistant to freezing stress and can germinate when conditions improve. The specimens collected were dioecious, with oogonia borne in the bifurcations of the rays. In several European countries, including Sweden and Great Britain, this species is considered extinct, while in others, it is classified as vulnerable or endangered, underscoring the importance of preserving its remaining habitats.

Tolypella glomerata was identified in the Geloi Wetland, specifically in the brackish marshes of Gela. This species is often found in slightly brackish waters and has a likely cosmopolitan distribution. The study noted that population density and fertility decreased as salinity increased, moving from the Acquitrino del Giunco Foglioso to the Pantano Pavoncelle. This observation aligns with previous research indicating that while T. glomerata adapts well to brackish environments, salinity remains a limiting factor for its reproductive success. The species has been reported in various parts of Italy, including Veneto, Emilia Romagna, and Tuscany, but its presence in the specific wetlands of eastern Sicily had not been documented until now. The findings suggest that brackish wetlands in Sicily may harbor unique algal communities that warrant further investigation.

The results of this study highlight the critical need for more comprehensive surveys of Characeae in Sicily. The distribution of these algae is not yet sufficiently known, and many areas remain unexamined. Filling these knowledge gaps is essential for developing effective conservation strategies and creating a national Red List for Characeae in Italy. Such a list would provide a standardized framework for assessing the conservation status of these species and guiding protection efforts. The study also emphasizes the ecological value of stoneworts in maintaining water quality and supporting aquatic biodiversity. By documenting new records and providing detailed morphological descriptions, the research contributes to the broader scientific understanding of freshwater algal ecology in the Mediterranean region.

Future research should focus on expanding surveys to other unexplored areas of Sicily and Italy, particularly in regions where data on Characeae distribution is scarce. Long-term monitoring of these populations will be crucial for detecting trends in abundance and health, especially in the context of climate change and human-induced environmental pressures. Collaboration between researchers, conservation organizations, and local authorities will be necessary to implement protective measures and ensure the survival of these ecologically important algae. The findings from eastern Sicily serve as a reminder of the hidden biodiversity that exists in seemingly ordinary wetlands and the urgent need to document and protect it before it is lost.

Subject of Research: Distribution and morphology of Characeae algae in eastern Sicily

Article Title: New Characeae ( Charophyceae , Charales ) report in eastern Sicily (Italy)

Article References: Pagana, I., Virzì, A., Zafarana, M. A., & Alongi, G. (2024). New Characeae (Charophyceae, Charales) report in eastern Sicily (Italy). Italian Botanist, 18, 109-122. https://doi.org/10.3897/italianbotanist.18.131661

Image Credits: AI Generated

DOI: 10.3897/italianbotanist.18.131661

Keywords: Characeae, Stoneworts, Sicily, Freshwater Algae, Biodiversity, Conservation, Wetlands, Bioindicators, Italy, Ecology, Charophyceae, Charales