Feeding habits and dietary overlap of age-0 winter flounder (Pseudopleuronectes americanus) and summer flounder (Paralichthys dentatus) in southern New England tidal rivers

Piscivory in age-0 summer flounder Paralichthys dentatus with a focus on predator-induced mortality of post-settlement winter flounder Pseudopleuronectes americanus

“…A complete description of the field sampling methodology is provided by Taylor et al (2016) and Taylor & Gervasi (2017). Briefly, age-0 summer flounder and winter flounder were collected from the Seekonk and Taunton Rivers from May through August/September each year from 2009 through 2015 ( Fig.…”

“…Water temperature (°C), salinity (ppt), and dissolved oxygen (mg l −1 ) were measured at each site per date by using a handheld YSI Model 85 meter, and these results were previously reported in Taylor & Gervasi (2017). Briefly, mean monthly water temperature and dissolved oxygen were comparable across river sites but varied temporally, ranging from 17.6−28.4°C (maximal in July) and 4.4−12.3 mg 1 −1 (decreased monthly), respectively.…”

“…Summer flounder previously preserved in 70% ethanol were measured for 'preserved' TL (TL p ; ±1 mm) in the laboratory. Prey were then extracted from summer flounder stomachs, transferred to 3.7 ml borosilicate vials with 70% ethanol, and later visually identified to the lowest practical taxon using stereoscopic microscopes, as reported by Taylor & Gervasi (2017). Each fish taxon's contribution to the diet of summer flounder was expressed as frequency of occurrence (%F ), which equaled the number of summer flounder stomachs containing a specific fish taxon divided by the total number of examined stomachs.…”

“…Most notably, the spatiotemporal overlap of flounder species could promote predator−prey interactions. Taylor & Gervasi (2017) examined the feeding habits of juvenile (age-0) summer flounder from the Seekonk and Taunton Rivers (Rhode Island and Massachusetts, respectively), 2 tidal rivers that adjoin the Narragansett Bay Estuary and serve as function-ally important nurseries (Taylor et al 2016). Direct visual analysis of summer flounder stomach contents revealed ontogenetic dietary shifts toward piscine prey.…”

“…Of the identifiable fish remains, winter flounder had the greatest contribution to summer flounder diet, thus verifying the existence of this predator− prey interaction in southern New England nurseries. This paper is an extension of Taylor & Gervasi (2017) and provides a more comprehensive analysis of piscivory in age-0 summer flounder, with a focus on their predatory impact on post-settlement winter flounder. For the latter, the objectives were 3-fold: (1) quantify the incidence of summer flounder predation on winter flounder, as revealed by conventional stomach content analysis and novel molecular genetic techniques; (2) ascertain the effect of spatiotemporally explicit abiotic and biotic factors on the predator−prey interaction; and (3) calculate the daily instantaneous and cumulative mortality rates of winter flounder, as caused by summer flounder predation, using a size-dependent deterministic model.…”