Trophic niches and diet shifts of juvenile mullet species coexisting in marine and estuarine habitats

Abstract

Food partitioning among coexisting species is often considered advantageous to minimize niche overlap and avoid inter-specific competition. Congeneric fish species such as the mullets Mugil curema and Mugil liza, which co-occur across marine and estuarine habitats, are good models to evaluate resource use and niche overlap or partitioning. We used stomach contents (SCA) and stable isotope analysis (SIA) to assess potential trophic shifts and changes in niche overlap associated with the mullets transitioning from marine to estuarine habitats. SIA included different fractions of organic matter in suspension and in the sediment to estimate the contribution of micro, nano and pico-organisms to the mullets’ diets. We hypothesized higher resource partitioning in the less resource-diverse system (marine surf-zone) than in the more diverse one (estuary). SCA showed diet differences between M. curema and M. liza according to the habitat. They showed distinct diets in the marine area (P < 0.001), but similar diets in the estuary (P = 0.226). A lower niche breadth was observed for both species in the marine area (M. curema = 0.03, M. liza = 0.06) compared with the estuary (M. curema = 0.14, M. liza = 0.16). Isotopic niches of both species were higher in the estuary (64.7%) compared with the marine area (0.7%). These findings corroborated our hypothesis of higher food partitioning in the marine surf-zone. We also demonstrated using SIA the shift from planktonic to benthic feeding following the recruitment of the mullets from the surf-zone into the estuary.

Body size mediates trophic interaction strength of novel fish assemblages under climate change

“…In addition to morphological characteristics, difference in prey availability (e.g. seasonal difference: Heng et al., 2019; Waraniak et al., 2019, spatial difference: Garcia et al., 2018; Vollrath et al., 2021) has previously been shown to affect the degree of dietary overlap between fish species. Spatial differences in biotic factors may explain why the same species pair did not show a consistent relationship across sampling sites (e.g.…”

Trophic Niche Differentiation in Two Sympatric Nuthatch Species (Sitta yunnanensis and Sitta nagaensis)

“…Direct observations revealed that the contribution rates of Diptera, Orthoptera, and Lepidoptera were highest, while stable isotope analysis showed that the contribution rates of Orthoptera, Hemiptera, and Hymenoptera were highest. This difference can be explained by methodological differences; stable isotope analyses reflect the food resources assimilated by animals rather than the food consumed by animals [42,43], while the direct observation method records food resources that are consumed. Lepidoptera had the lowest contribution rate in the stable isotope analysis (2.29% for S. yunnanensis and 4.12% for S. nagaensis).…”

Diet and food assimilation of the Plata pompano Trachinotus marginatus Cuvier, 1832 in a subtropical sandy beach inferred by stomach content and stable isotope analyzes

“…In order to obtain an SOM sample, about 2 cm of surface sediment was removed using a 10 cm diameter plastic pipe. These organic sources were collected to serve as proxies of the isotopic variability of microalgae and debris (Fry, 2006;Vollrath et al, 2021), which constitutes the main sources of primary organic matter sustaining consumers in sandy beaches along the studied coastal plain (Pinotti et al, 2014;Garcia et al, 2019aGarcia et al, , 2019b. Other primary producers, such as floating aquatic macrophytes, seagrasses and macroalgae beds, are usually absent in the sandy beaches of this coastline (Odebrecht et al, 2010).…”