High Tolerance of the Invasive Submersed Plant Cabomba Caroliniana to Underwater Light Attenuation May Facilitate Its Invasiveness

Invasion by introduced species has been listed as one of the main threats to freshwater biodiversity worldwide. Invasive species have resulted in reduced abundance and diversity of native species in invaded natural habitats and caused harm to human society. However, the mechanisms of plant invasion in natural habitats remain controversial. 

In the late 1980s, Carolina fanwort (Cabomba caroliniana) was introduced to China as an aquarium plant because of its beautiful fan-shaped dissected leaves, and soon escaped as a serious invasive threat to freshwater ecosystems. It was listed as an invasive species in the 4th patch of ‘the List of Alien Invasive Species in China's Natural Ecosystem’ by the Ministry of Ecology and Environment of China in 2016. 

Researchers, led by Dr. HUANG Xiaolong, from Prof. LI Kuanyi's team from the Nanjing Institute of Geography and Limnology of the Chinese Academy of Sciences, along with their international collaborators, have investigated why C. caroliniana is so successful in invading China through field investigations and a mesocosm experiment. 

Their findings were published in the Diversity and Distributions on Mar. 15, 2023. 

In the field investigations, seventy-two aquatic plant quadrats dominated by one of three plant species (native Hydrilla verticillata, Myriophyllum spicatum and invasive C. caroliniana) were collected in East China. The field investigations showed that water turbidity and underwater photosynthetically active radiation (PAR) were the main factors affecting the relative coverage and abundance of the three submerged plants. 

Subsequently, a mesocosm experiment was conducted to explore the responses of the functional traits of the three species to different levels of underwater PAR. The results showed that the performance of C. caroliniana was superior to that of the two native species at low underwater PAR, indicating a better ability of this species to attenuate light. 

“If underwater darkening continues, submerged plants that are not suitable for or sufficiently tolerant of growth under these conditions may vanish, and plants that are suitable for these conditions, typically invasive plants, may prosper,” said Dr. HUANG. 

The results also indicate that if water bodies maintain low turbidity and a high underwater PAR after ecological restoration, the dominance of native aquatic plant vegetation will be achieved, thus constraining the growth and spread of invasive plants. 

“The ecological restoration of aquatic habitats that relies on the reconstruction of aquatic vegetation is a feasible strategy, but it must be based on habitat transformation. After the ecological restoration is completed, water bodies can maintain low turbidity and a high underwater PAR, and natural restoration of aquatic vegetation can be achieved,” said Dr. HUANG.

Cabomba caroliniana in its introduced natural habitats


(online on Jan. 31 2023)


TAN Lei 

Nanjing Institute of Geography and Limnology