Changing Isotopic Food Webs of Two Economically Important Fish in Mediterranean Coastal Lakes with Different Trophic Status

• Published in: Applied Sciences
• Main Authors: Simona Sporta Caputi, Giulio Careddu, Edoardo Calizza, Federico Fiorentino, Deborah Maccapan, Loreto Rossi, Maria Letizia Costantini
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2020
• Subjects: food webs; Mediterranean coastal lakes; nitrogen pollution; stable isotopes; trophic relationships; Anguilla anguilla; Technology; T; Engineering (General). Civil engineering (General); TA1-2040; Biology (General); QH301-705.5; Physics; QC1-999; Chemistry; QD1-999
• Online Access: https://doi.org/10.3390/app10082756; https://doaj.org/article/e1ef69217b3d4d6f9f9d5487788740d0

Transitional waters are highly productive ecosystems, providing essential goods and services to the biosphere and human population. Human influence in coastal areas exposes these ecosystems to continuous internal and external disturbance. Nitrogen-loads can affect the composition of the resident community and the trophic relationships between and within species, including fish. Based on carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope analyses of individuals, we explored the feeding behaviour of two ecologically and economically important omnivorous fish, the eel Anguilla anguilla and the seabream Diplodus annularis , in three neighbouring lakes characterised by different trophic conditions. We found that A. anguilla showed greater generalism in the eutrophic lake due to the increased contribution of basal resources and invertebrates to its diet. By contrast, the diet of D. annularis, which was mainly based on invertebrate species, became more specialised, focusing especially on polychaetes. Our results suggest that changes in macroinvertebrate and fish community composition, coupled with anthropogenic pressure, affect the trophic strategies of high trophic level consumers such as A. anguilla and D. annularis . Detailed food web descriptions based on the feeding choices of isotopic trophospecies (here Isotopic Trophic Units, ITUs) enable identification of the prey taxa crucial for the persistence of omnivorous fish stocks, thus providing useful information for their management and habitat conservation.