Diets and Resource Partitioning among Three Sympatric Gurnards in Northeastern Tasmanian Waters, Australia

Abstract

Dietary niches can support the coexistence of closely related sympatric species in marine systems, which can lead to the presence of greater abundances of those species that can potentially support their fisheries or greater abundances for other fish species that prey upon those species. Dietary relationships for three species of gurnard (Family Triglidae) that occur together in the benthic coastal environment of northeastern Tasmania, Australia (Red Gurnard Chelidonichthys kumu, Grooved Gurnard Lepidotrigla modesta, and Roundsnout Gurnard Lepidotrigla mulhalli), were examined for the presence of such dietary niches. The species are either fishery-important (Red Gurnard) or provide prey (Grooved Gurnard and Roundsnout Gurnard) for fishery-important species (e.g., Platycephalidae and Zeidae). Based on stomach content analyses, all three gurnards were shown to be bottomfeeding carnivores that consumed mainly benthic crustaceans, particularly decapods and amphipods, with teleosts also being important in the diets of only the larger Red Gurnard. Nonmetric multidimensional scaling ordination and multivariate analyses based on volumetric contributions of different prey taxa to the stomach contents revealed significant differences in dietary composition among all three species, implying a partitioning of food resources. Size-related and temporal changes in dietary composition were each significant among the three gurnards, but there were no interactions between body size and time. Principal components analysis of head and mouth morphology demonstrated that mouth protrusiveness was the dominant morphological difference among species, which may in part account for the niche partitioning observed from the stomach content analysis. Given the important role of gurnards in benthic food webs, these relationships will improve the specification of ecosystembased fisheries models and their ability to predict the effects of environmental and anthropogenic perturbations.

Seasonal and developmental diet shifts in sympatric and allopatric intertidal gobies determined by stomach content and stable isotope analysis

“…The method followed was that given by Park et al . (2017a), where a curve was considered to asymptote if a minimum of 10 previous values of the total number of prey taxa were in range of the asymptotic number of prey ± 0.5 (Huveneers et al ., 2007).…”

“…Cumulative prey curves were constructed to ensure that the stomachs analysed were of sufficient sample size to adequately describe the diet of each species (Ferry & Cailliet, 1996). The method followed was that given by Park et al (2017a), where a curve was considered to asymptote if a minimum of 10 previous values of the total number of prey taxa were in range of the asymptotic number of prey ± 0.5 (Huveneers et al, 2007).…”

“…Stable isotope analysis is becoming an increasingly common tool used to investigate trophic niche overlap (Barreiros et al ., 2004; Córdova‐Tapia et al ., 2015; Eurich et al ., 2019) and the preferred means to measure prey contribution to diet over time (Park et al ., 2017a; Post, 2002). Such data were traditionally sought using stomach content analyses, but variable assimilation rates of prey items within the stomach were often misinterpreted (Baker et al ., 2014; Bearhop et al ., 2004), leading to discrepancies in reported diets or trophic niches in some species ( e.g ., Boyle & Horn, 2006).…”

Trophic niche of Australian cownose rays (Rhinoptera neglecta) and whitespotted eagle rays (Aetobatus ocellatus) along the east coast of Australia

“…Sexually mature R. neglecta have a disc width of 100 cm whereas A. ocellatus reach 300 cm (Weigmann, 2016). For many marine species, body size determines mouth gape and potentially mouth protrusion, which can limit the size of consumable prey, affect foraging efficiency (Fisher et al, 2011;Park et al, 2017) and drive trophic relationships (Hayden et al, 2019). Furthermore, differences in head, jaw and tooth plate morphology of rhinopterids and aetobatids (McEachran & Aschliman, 2004;Summers, 2000) may Although ethanol is not the recommended method of preservation for stable isotope samples, it is often unavoidable where freezing is difficult or if using historical samples (Burgess & Bennett, 2017;Kelly et al, 2006;Kim & Koch, 2012;Olin et al, 2014).…”

Meta-Transcriptomic Identification of Divergent Amnoonviridae in Fish

“…To help address whether the Amnoonviridae might be present in a wider range of vertebrate taxa, we screened for their presence using a meta-transcriptomic analysis of marine fish sampled in Australia and China, combined with data mining of published transcriptomes. [10]. Ten individuals from each species were caught and stored separately.…”