State of aquatic invasive species in tropical India: An overview

Abstract

India, a megadiverse tropical country is grappling with the rising trend of aquatic invasions. Out of 532 introduced non-native fish, 16 species of freshwater aquaculture and aquarium were assessed invasive by using a risk assessment protocol, ‘Fish Invasiveness Screening Test’. Six major identified invasion pathways of the aquatic invasive species were inadvertent or deliberate releases, escapes, contaminants from hatcheries, river corridors, stowaways and unaided introductions. Invasion mechanism further elucidated the factors promoting successful invasion in freshwater ecosystems. For predictive future performance of invasive fish, the concrete and predictive values based on mean abundance by weight was calculated. Over 28.67% and 29.02 % persistent increased yield of the invasive Tilapia and Common Carp respectively was predicted in the Ganga river in the coming decades. Single species Tilapia invasion facilitated multiple species fish invasion, manifesting in invasion meltdown. The trophic changes due to fish invasion exhibited biotic homogenization with trophic downgrading. Aquatic invasive species were found highly competitive interacting with native species causing serious biodiversity loss, health hazards, and economic damage consequently affecting the ecosystem services. In spite of available regulatory approaches and guidelines to manage aquatic invasive species, fish invasion has been on the rise. This paper suggests modifications and stringent implementation of the existing regulatory mechanisms besides adopting linkages, cutting-edge research on invasion science and modern molecular containment tools for effective management.

Nile Tilapia (Oreochromis niloticus Linnaeus, 1758) Invasion Caused Trophic Structure Disruptions of Fish Communities in the South China River—Pearl River

“…Specifically, Nile tilapia invasion compressed the isotopic niche space of native invertivores, omnivores, piscivores, and planktivores (all had a lower TA and a lower SEA than in the reference river). Trophic changes due to fish invasion can also exhibit biotic homogenization with trophic downgrading [ 54 ]. The size of the SEA of native fish communities in the invaded Dongjiang River was also significantly smaller than that in the reference Beijiang River, indicating that Nile tilapia were mainly located at the center of the isotopic niche space [ 8 ].…”

Environmental drivers dependent habitat expansion of introduced alien trout (Salmo trutta fario and Oncorhynchus mykiss) in the Himalayan ecosystem and management concerns in the time of climate change

“…Trout streams in Himalaya are typically fast-owing, soft-water with rocky stony riverbeds and clear water within the temperature range of 10-18°C. Understanding the spatial behaviour of sh, and how they respond to environmental variation is critical to ensure their effective management, especially in the time of growing pressures such as climate change (Tewari et al, 2016), invasive species (Singh and Lakra, 2011;Singh, 2021) Despite the long history of trout in India, hardly any information exists on the ecology of the sh species under environmental drivers which may predict the success and limitation of its distribution and habitat expansion. The changing environmental parameters due to climate change or changing ecological conditions of the Himalayan aquatic ecosystem (Kattel, 2021) may form extended habitat for any introduced species in the space as a consequence of changes in environments.…”

“…The changing environmental parameters due to climate change or changing ecological conditions of the Himalayan aquatic ecosystem (Kattel, 2021) may form extended habitat for any introduced species in the space as a consequence of changes in environments. Ecological and environmental information are important for understanding spatial and temporal variability in distribution of any introduced alien sh species and also for providing the necessary feedback to guide policy options in the context of sh invasions which are recognized as the major threats to biodiversity (Singh & Lakra, 2011;Thapliyal et al, 2016;Araujo, et al, 2019;Hosegawa, 2020;Johal et al, 2021;Sharma et al, 2021;Singh, 2021). Freshwater ecosystems in Himalaya present unique challenges to its sh diversity due to their linear spatial orientation and their association with upland habitat variables (Kattel, 2021).…”