Comparative Visual Function in Predatory Fishes from the Indian River Lagoon

Visual temporal resolution and spectral sensitivity of three coastal teleost species (common snook [Centropomus undecimalis], gray snapper [Lutjanus griseus], and pinfish [Lagodon rhomboides]) were investigated by electroretinogram. Temporal resolution was quantified under photopic and scotopic conditions using response waveform dynamics and maximum critical flicker fusion frequency (CFFmax). Photopic CFFmax was significantly higher than scotopic CFFmax in all species. The snapper had the shortest photoreceptor response latency time (26.7 ms) and the highest CFFmax (47 Hz), suggesting that its eyes are adapted for a brighter photic environment. In contrast, the snook had the longest response latency time (36.8 ms) and lowest CFFmax (40 Hz), indicating that its eyes are adapted for a dimmer environment or nocturnal lifestyle. Species spectral responses ranged from 360 to 620 nm and revealed the presence of rods sensitive to dim and twilight conditions, as well as multiple cone visual pigments providing the basis for color and contrast discrimination. Collectively, our results demonstrate differences in visual function among species inhabiting the Indian River Lagoon system, representative of their unique ecology and life histories

A Physiological Analysis of Color Vision in Batoid Elasmobranchs

The potential for color vision in elasmobranchs has been studied in detail; however, a high degree of variation exists among the group. Evidence for ultraviolet (UV) vision is lacking, despite the presence of UV vision in every other vertebrate class. An integrative physiological approach was used to investigate color and ultraviolet vision in cownose rays and yellow stingrays, two batoids that inhabit different spectral environments. Both species had peaks in UV, short, medium, and long wavelength spectral regions in dark-, light-, and chromatic-adapted electroretinograms. Although no UV cones were found with microspectrophotometric analysis, both rays had multiple cone visual pigments with λmax at 470 and 551 nm in cownose rays (Rhinoptera bonasus) and 475, 533, and 562 nm in yellow stingrays (Urobatis jamaicensis). The same analysis demonstrated that both species had rod λmax at 500 and 499 nm, respectively. The lens and cornea of cownose rays maximally transmitted wavelengths greater than 350 nm and greater than 376 nm in yellow stingrays. These results support the potential for color vision in these species and future investigations should reveal the extent to which color discrimination is significant in a behavioral context

Effects of Temperature and Anesthesia on Visual Temporal Resolution in Elasmobranch Fishes

An organism’s ability to track moving objects, or temporal resolution, has been correlated to habitat and lifestyle, and can be further modulated by temperature and light intensity fluctuations within the environment. Photopic (bright-light/day time) vision is typically faster than scotopic (dim-light/night time) because visual sensitivity is greater in dim light and integration time must be slowed to allow for capture of the maximum number of photons. Higher temperatures result in increased temporal resolution in both endothermic and non-endothermic fishes. Previous studies have used either anesthetized or paralyzed fishes to determine temporal resolution, measured as the maximum critical flicker fusion frequency (CFFmax). However, sedation with the anesthetic, tricaine methanesulfonate (MS-222), is thought to suppress sensory system responses, although empirical evidence is lacking. Therefore, we quantified scotopic and photopic CFFmax in the yellow stingray, Urobatis jamaicensis, at the extremes of its temperature range, 20°C and 30°C, and immobilized with anesthesia, MS-222, or a paralytic, Pavulon. Both low temperature and anesthesia (MS-222) reduced CFFmax. With an increase of 10°C, CFFmax doubled from 12Hz to 25.3Hz (photopic) under Pavulon, whereas CFFmax increased by only 4Hz, from 6.7Hz to 10.7Hz (photopic) under MS-222 anesthesia. In general, MS-222 anesthesia minimized the effects of both temperature and light-adaptation compared to Pavulon. Yellow stingray CFFmax was similar to the skate, another benthic batoid, but slower than shark species studied with the same technique. These results illustrate the effects of light adaptation, temperature, and anesthesia on visual function within the elasmobranch fishes

Misunderstanding the Female Athlete Triad: Refuting the IOC Consensus Statement on Relative Energy Deficiency in Sport (RED-S)

We are concerned that readers of the IOC paper will be confused and misled by the poorly referenced statements and frank (and sometimes dangerous) errors in the paper. The IOC authors should publish a correction of these and other errors noted. Broadening research of low energy availability in other groups, such as the male athlete, athletes of diverse ethnicities and the disabled athlete may help to advance science and may one day warrant introduction of a specific term for whatever serious clinical sequelae of energy deficiency may be discovered in future research on men. Research on the “Female Athlete Triad” has forged a platform from which a broad array of healthcare providers (e.g., physicians, sport dietitians, mental health professionals and athletic trainers) have made great strides in learning how to manage and treat affected women. Research on the “Female Athlete Triad” has also been translated to the lay public such that more and more affected female athletes and exercising women willingly seek education, prevention and treatment. Meanwhile, subsuming the term “Female Athlete Triad” under the umbrella of the term RED-S has the potential to confuse rather than enlighten, and undo decades of work educating and advocating for awareness, prevention and treatment for the Triad. The individual most impacted by the de-emphasis on the Triad will be the female athlete herself. The overwhelming clinical importance of the Female Athlete Triad compared with other conditions under the proposed RED-S umbrella will continue to make a specific reference for the Triad useful for those who deal with it, including physicians, coaches, sport dietitians, athletics trainers, parents and, most importantly, female athletes. As such, efforts promoting awareness, prevention and treatment of the Female Athlete Triad remain critically important and should not be overshadowed by an ill-conceived and poorly defended new construct