Fish stable isotope community structure of a Bahamian coral reef

• Published in: Marine biology Vol. 166; no. 12; pp. 1 - 14
• Main Authors: Zhu, Yiou, Newman, Steven P., Reid, William D. K., Polunin, Nicholas V. C.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2019; Springer; Springer Nature B.V
• Subjects: Aquatic environment; Biomedical and Life Sciences; Body mass; Body size; Community structure; Coral reefs; Coral reefs and islands; Ecosystems; Fish; Fishes; Food chains; Food webs; Freshwater & Marine Ecology; Guilds; Herbivores; Isotopes; Life Sciences; Marine & Freshwater Sciences; Marine biology; Marine ecosystems; Marine fishes; Marine invertebrates; Mass; Microbiology; Muscles; Niches; Oceanography; Omnivores; Original Paper; Piscivores; Predators; Prey; Reef fish; Reef fishes; Species; Stable isotopes; Trophic structure; Zoology; United Kingdom
• ISSN: 0025-3162; 1432-1793
• DOI: 10.1007/s00227-019-3599-9

Stable isotopes have provided important insight into the trophic structure and interaction in many ecosystems, but to date have scarcely been applied to the complex food webs of coral reefs. We sampled white muscle tissues from the fish species composing 80% of the biomass in the 4–512 g body mass range at Cape Eleuthera (the Bahamas) in order to examine isotopic niches characterised by δ 13 C and δ 15 N data and explore whether fish body size is a driver of trophic position based on δ 15 N. We found the planktivore isotopic niche was distinct from those of the other trophic guilds suggesting the unique isotopic baseline of pelagic production sources. Other trophic guilds showed some level of overlap among them especially in the δ 13 C value which is attributable to source omnivory. Surprising features of the isotopic niches included the benthivore Halichoeres pictus , herbivores Acanthurus coeruleus and Coryphopterus personatus and omnivore Thalassoma bifasciatum being close to the planktivore guild, while the piscivore Aulostomus maculatus came within the omnivore and herbivore ellipses. These characterisations contradicted the simple trophic categories normally assigned to these species. δ 15 N tended to increase with body mass in most species, and at community level, the linear δ 15 N–log 2 body mass relationship pointing to a mean predator–prey mass ratio of 1047:1 and a relatively long food chain compared with studies in other aquatic systems. This first demonstration of a positive δ 15 N–body mass relationship in a coral reef fish community suggested that the Cape Eleuthera coral reef food web was likely supported by one main pathway and bigger reef fishes tended to feed at higher trophic position. Such finding is similar to other marine ecosystems (e.g. North Sea).