Comparative visual function in five sciaenid fishes inhabiting Chesapeake Bay

Maintaining optimal visual performance is a difficult task in the photodynamic coastal and estuarine waters in which western North Atlantic sciaenid fishes support substantial commercial and recreational fisheries. Unavoidable tradeoffs exist between visual sensitivity and resolution, yet sciaenid visual systems have not been characterized despite strong species-specific ecomorphological and microhabitat differentiation. We therefore used electroretinographic techniques to describe the light sensitivities, temporal properties, and spectral characteristics of the visual systems of five sciaenids common to Chesapeake Bay, USA: weakfish (Cynoscion regalis), spotted seatrout (Cynoscion nebulosus), red drum (Sciaenops ocellatus), Atlantic croaker (Micropogonias undulatus) and spot (Leiostomus xanthurus). Benthic sciaenids exhibited higher sensitivities and broader dynamic ranges in white light V/logI experiments than more pelagic forms. Sensitivities of the former were at the lower (more sensitive) end of an emerging continuum for coastal fishes. Flicker fusion frequency experiments revealed significant interspecific differences at maximum intensities that correlated with lifestyle and habitat, but no specific differences at dimmer intensities. Spectral responses of most sciaenids spanned 400-610 nm, with significant diel differences in weakfish and Atlantic croaker. Weakfish, a crepuscular predator, also responded to ultraviolet wavelengths; this characteristic may be more useful under less turbid conditions. Collectively, these results suggest that sciaenids are well adapted to the dynamic photoclimate of the coastal and estuarine waters they inhabit. However, the recent anthropogenic degradation of water quality in coastal environments, at a pace faster than the evolution of visual systems, has amplified the importance of characterizing visual function in managed aquatic fauna

Comparative visual function in four piscivorous fishes inhabiting Chesapeake Bay

Maintaining optimal visual performance is a difficult task in photodynamic coastal and estuarine waters because of the unavoidable tradeoffs between luminous sensitivity and spatial and temporal resolution, yet the visual systems of coastal piscivores remain understudied despite differences in their ecomorphology and microhabitat use. We therefore used electroretinographic techniques to describe the light sensitivities, temporal properties and spectral sensitivities of the visual systems of four piscivorous fishes common to coastal and estuarine waters of the western North Atlantic: striped bass (Morone saxatilis), bluefish (Pomatomus saltatrix), summer flounder (Paralichthys dentatus) and cobia (Rachycentron canadum). Benthic summer flounder exhibited higher luminous sensitivity and broader dynamic range than the three pelagic foragers. The former were at the more sensitive end of an emerging continuum for coastal fishes. By contrast, pelagic species were comparatively less sensitive, but showed larger day-night differences, consistent with their use of diel light-variant photic habitats. Flicker fusion frequency experiments revealed significant interspecific differences at maximum intensities that correlated with lifestyle and habitat. Spectral responses of most species spanned 400-610nm, with significant day-night differences in striped bass and bluefish. Anadromous striped bass additionally responded to longer wavelengths, similar to many freshwater fishes. Collectively, these results suggest that pelagic piscivores are well adapted to bright photoclimates, which may be at odds with the modern state of eutrified coastal and estuarine waters that they utilize. Recent anthropogenic degradation of water quality in coastal environments, at a pace faster than the evolution of visual systems, may impede visually foraging piscivores, change selected prey, and eventually restructure ecosystems

Adaptive migratory orientation of an invasive pest on a new continent

This is the final version. Available on open access from Cell Press via the DOI in this recordData and code availability: The authors declare that the data supporting the findings of this study are available within the paper and its Supplemental Information. Individual data files used to generate the figures in the paper have been deposited in Mendeley Data (https://doi.org/10.17632/6jkvpybswd.1). Custom-written Visual Basic software Flash Flight Simulator Data Acquisition System and Mapflows have been deposited in Mendeley Data (https://doi.org/10.17632/6jkvpybswd.1). Custom single-chip used for data acquisition is available from the corresponding authors upon reasonable request ([email protected], [email protected]). Any additional information required to reanalyze the data reported in this work paper is available from the lead contact upon request.Many species of insects undertake long-range, seasonally reversed migrations, displaying sophisticated orientation behaviors to optimize their migratory trajectories. However, when invasive insects arrive in new biogeographical regions, it is unclear if migrants retain (or how quickly they regain) ancestral migratory traits, such as seasonally preferred flight headings. Here we present behavioral evidence that an invasive migratory pest, the fall armyworm moth (Spodoptera frugiperda), a native of the Americas, exhibited locally adaptive migratory orientation less than three years after arriving on a new continent. Specimens collected from China showed flight orientations directed north-northwest in spring and southwest in autumn, and this would promote seasonal forward and return migrations in East Asia. We also show that the driver of the seasonal switch in orientation direction is photoperiod. Our results thus provide a clear example of an invasive insect that has rapidly exhibited adaptive migratory behaviors, either inherited or newly evolved, in a completely alien environment.National Key Research and Development Program of Chin

A Feedback Neural Network for Small Target Motion Detection in Cluttered Backgrounds

Small target motion detection is critical for insects to search for and track mates or prey which always appear as small dim speckles in the visual field. A class of specific neurons, called small target motion detectors (STMDs), has been characterized by exquisite sensitivity for small target motion. Understanding and analyzing visual pathway of STMD neurons are beneficial to design artificial visual systems for small target motion detection. Feedback loops have been widely identified in visual neural circuits and play an important role in target detection. However, if there exists a feedback loop in the STMD visual pathway or if a feedback loop could significantly improve the detection performance of STMD neurons, is unclear. In this paper, we propose a feedback neural network for small target motion detection against naturally cluttered backgrounds. In order to form a feedback loop, model output is temporally delayed and relayed to previous neural layer as feedback signal. Extensive experiments showed that the significant improvement of the proposed feedback neural network over the existing STMD-based models for small target motion detection

Night Myopia Studied with an Adaptive Optics Visual Analyzer

PURPOSE: Eyes with distant objects in focus in daylight are thought to become myopic in dim light. This phenomenon, often called "night myopia" has been studied extensively for several decades. However, despite its general acceptance, its magnitude and causes are still controversial. A series of experiments were performed to understand night myopia in greater detail. METHODS: We used an adaptive optics instrument operating in invisible infrared light to elucidate the actual magnitude of night myopia and its main causes. The experimental setup allowed the manipulation of the eye's aberrations (and particularly spherical aberration) as well as the use of monochromatic and polychromatic stimuli. Eight subjects with normal vision monocularly determined their best focus position subjectively for a Maltese cross stimulus at different levels of luminance, from the baseline condition of 20 cd/m(2) to the lowest luminance of 22 × 10(-6) cd/m(2). While subjects performed the focusing tasks, their eye's defocus and aberrations were continuously measured with the 1050-nm Hartmann-Shack sensor incorporated in the adaptive optics instrument. The experiment was repeated for a variety of controlled conditions incorporating specific aberrations of the eye and chromatic content of the stimuli. RESULTS: We found large inter-subject variability and an average of -0.8 D myopic shift for low light conditions. The main cause responsible for night myopia was the accommodation shift occurring at low light levels. Other factors, traditionally suggested to explain night myopia, such as chromatic and spherical aberrations, have a much smaller effect in this mechanism. CONCLUSIONS: An adaptive optics visual analyzer was applied to study the phenomenon of night myopia. We found that the defocus shift occurring in dim light is mainly due to accommodation errors

Light in the Polar Night

How much light isa vailable for biological processes during Polar Night? This question appears simple enough. But the reality is that conventional light sen- sors for measuring visible light (~350 to ~700 nm) have not been sensitive enough to answer it. Beyond this technical challenge, “light” is a general term that must be qualified in terms of “light climate” before it has meaning for biological systems. In this chapter, we provide an answer to the question posed above and explore aspects of light climate during Polar Night with relevance to biology, specifically, how Polar Night is defined by solar elevation, atmospheric light in Polar Night and its propaga- tion underwater, bioluminescence in Polar Night and the concept of Polar Night as a deep-sea analogue, light pollution, and future perspectives. This chapter focuses on the quantity and quality of light present during Polar Night, while subsequent chapters in this volume focus on specific biological effects of this light for algae (Chap. “Marine Micro- and Macroalgae in the Polar Night”), zooplankton (Chaps.“Zooplankton in the Polar Night” and “Biological Clocks and Rhythms in Polar Organisms”), and fish (Chap. “Fish Ecology in the Polar Night”)

Visual Coding in Locust Photoreceptors

Information capture by photoreceptors ultimately limits the quality of visual processing in the brain. Using conventional sharp microelectrodes, we studied how locust photoreceptors encode random (white-noise, WN) and naturalistic (1/f stimuli, NS) light patterns in vivo and how this coding changes with mean illumination and ambient temperature. We also examined the role of their plasma membrane in shaping voltage responses. We found that brightening or warming increase and accelerate voltage responses, but reduce noise, enabling photoreceptors to encode more information. For WN stimuli, this was accompanied by broadening of the linear frequency range. On the contrary, with NS the signaling took place within a constant bandwidth, possibly revealing a ‘preference’ for inputs with 1/f statistics. The faster signaling was caused by acceleration of the elementary phototransduction current - leading to bumps - and their distribution. The membrane linearly translated phototransduction currents into voltage responses without limiting the throughput of these messages. As the bumps reflected fast changes in membrane resistance, the data suggest that their shape is predominantly driven by fast changes in the light-gated conductance. On the other hand, the slower bump latency distribution is likely to represent slower enzymatic intracellular reactions. Furthermore, the Q10s of bump duration and latency distribution depended on light intensity. Altogether, this study suggests that biochemical constraints imposed upon signaling change continuously as locust photoreceptors adapt to environmental light and temperature conditions

Identification of a Circadian Clock-Controlled Neural Pathway in the Rabbit Retina

Background: Although the circadian clock in the mammalian retina regulates many physiological processes in the retina, it is not known whether and how the clock controls the neuronal pathways involved in visual processing. Methodology/Principal Findings: By recording the light responses of rabbit axonless (A-type) horizontal cells under darkadapted conditions in both the day and night, we found that rod input to these cells was substantially increased at night under control conditions and following selective blockade of dopamine D2, but not D1, receptors during the day, so that the horizontal cells responded to very dim light at night but not in the day. Using neurobiotin tracer labeling, we also found that the extent of tracer coupling between rabbit rods and cones was more extensive during the night, compared to the day, and more extensive in the day following D 2 receptor blockade. Because A-type horizontal cells make synaptic contact exclusively with cones, these observations indicate that the circadian clock in the mammalian retina substantially increases rod input to A-type horizontal cells at night by enhancing rod-cone coupling. Moreover, the clock-induced increase in D2 receptor activation during the day decreases rod-cone coupling so that rod input to A-type horizontal cells is minimal. Conclusions/Significance: Considered together, these results identify the rod-cone gap junction as a key site in mammals through which the retinal clock, using dopamine activation of D2 receptors, controls signal flow in the day and night fro