Feeding niche overlap between native and alien fishes in Swat River, Khyber Pakhtunkhwa, Pakistan

• Published in: Environmental biology of fishes 2022-04, Vol.105 (4), p.509-518
• Main Authors: Said, Amir, Imran, Muhammad, Waseem, Muhammad Tahir, Khan, Abdul Majid, Khalique, Noman, Sarwar, Ghulam, Ahmad, Rana Manzoor
• Format: Article
• Language: English
• Subjects: Animal Systematics/Taxonomy/Biogeography; Aquatic ecosystems; Biodiversity; Biodiversity loss; Biomedical and Life Sciences; Carp; Cyprinus carpio; Environment; Feeding; Fish; Food; Food sources; Foods; Freshwater; Freshwater & Marine Ecology; Freshwater ecosystems; Freshwater fishes; Ichthyofauna; Indigenous species; Inland water environment; Introduced species; Isotopes; Life Sciences; Native organisms; Nature Conservation; Niche overlap; Niches; Nitrogen isotopes; Rivers; Stable isotopes; Trophic levels; Trophic structure; Zoology
• ISSN: 0378-1909; 1573-5133
• DOI: 10.1007/s10641-022-01254-4

One of the major causes of biodiversity loss in freshwater ecosystems is the introduction of alien species. The common carp has been established in every freshwater ecosystem of Pakistan and is a leading threat to the native ichthyofauna. In the present study, stable isotopes of nitrogen and carbon (δ 15 N and δ 13 C) are used to explore the feeding niche overlap among alien Cyprinus carpio (common carp) and native omnivorous fishes including Tor putitora (mahseer) and Barilius pakistanicus (Pakistani chalwa) from Swat River, Khyber Pakhtunkhwa (KP), Pakistan. Differences in mean values of δ 15 N and δ 13 C among the species were found non-significant. Community-wide metrics within δ 13 C-δ 15 N bi-plot space reflecting vital aspects of the trophic structure were also calculated. It was found that all the selected species were feeding at the same trophic level, whereas niche size and trophic diversity of common carp was greater compared to both of the native species which indicated that this alien fish is a highly opportunistic feeder on different food items with multiple basal resources having a wide range of δ 13 C values. Mahseer occupied a very small trophic niche within the niche space of common carp. This shows that mahseer is relatively a specialist feeder on fewer food sources; hence, mahseer might be subjected to the higher threat posed by the alien species. The trophic niche area of Pakistani chalwa was also smaller than common carp but wider than mahseer indicating a relatively lower degree of overlap with common carp.