First record of redneck goby Schismatogobius deraniyagalai (Teleostei: Gobiidae) from Seethanathi river, Karnataka, Southern India.

Schismatogobius deraniyagalai is recorded from the Seethanathi River of Karnataka state in the southern part of India. Previous records of these species were from the streams in Kerala of India and from freshwater habitats of Sri Lanka. Herein we report the occurrence of this species in Seethanathi River showing its distribution extended further north along the west coast of Peninsular India

First record of redneck goby Schismatogobius deraniyagalai (Teleostei: Gobiidae) from Seethanathi river, Karnataka, Southern India.

Schismatogobius deraniyagalai is recorded from the Seethanathi River of Karnataka state in the southern part of India. Previous records of these species were from the streams in Kerala of India and from freshwater habitats of Sri Lanka. Herein we report the occurrence of this species in Seethanathi River showing its distribution extended further north along the west coast of Peninsular India

A new record of the dwarf snakehead, Channa ornatipinnis Britz 2007 (Perciformes: Channidae) from India

The snakehead of the family are represented 33 species from Asia of which two species Channa ornatipinnis and C. pulchra were recently described from Myanmar. The recent record of C. ornatipinnis from Tuivawl river, Tuivawl village in Champhai district, Mizoram, India is of  ichthyological interes

Interbasin Water Transfer, Riverine Connectivity, and Spatial Controls on Fish Biodiversity

BACKGROUND: Large-scale inter-basin water transfer (IBWT) projects are commonly proposed as solutions to water distribution and supply problems. These problems are likely to intensify under future population growth and climate change scenarios. Scarce data on the distribution of freshwater fishes frequently limits the ability to assess the potential implications of an IBWT project on freshwater fish communities. Because connectivity in habitat networks is expected to be critical to species' biogeography, consideration of changes in the relative isolation of riverine networks may provide a strategy for controlling impacts of IBWTs on freshwater fish communities. METHODS/PRINCIPAL FINDINGS: Using empirical data on the current patterns of freshwater fish biodiversity for rivers of peninsular India, we show here how the spatial changes alone under an archetypal IBWT project will (1) reduce freshwater fish biodiversity system-wide, (2) alter patterns of local species richness, (3) expand distributions of widespread species throughout peninsular rivers, and (4) decrease community richness by increasing inter-basin similarity (a mechanism for the observed decrease in biodiversity). Given the complexity of the IBWT, many paths to partial or full completion of the project are possible. We evaluate two strategies for step-wise implementation of the 11 canals, based on economic or ecological considerations. We find that for each step in the project, the impacts on freshwater fish communities are sensitive to which canal is added to the network. CONCLUSIONS/SIGNIFICANCE: Importantly, ecological impacts can be reduced by associating the sequence in which canals are added to characteristics of the links, except for the case when all 11 canals are implemented simultaneously (at which point the sequence of canal addition is inconsequential). By identifying the fundamental relationship between the geometry of riverine networks and freshwater fish biodiversity, our results will aid in assessing impacts of IBWT projects and balancing ecosystem and societal demands for freshwater, even in cases where biodiversity data are limited

System connectivity underlies the loss of species (TSR, total species richness) for both the economic (open red circles) and the ecological (closed blue circles) linking strategies.

<p>This relationship holds for different measures of connectivity. Average degree (panel A; size of circles relative to the average number of connected sub-basins of the peninsular river networks, which increase as unconnected rivers are linked via canals), largest network size (panel B; size of circles relative to the average degree), decrease in the number of river networks (panel C; size of circles relative to the average degree), and number of networks consisting of a single sub-basin (panel D; size of circles relative to the average degree).</p

Map of peninsular India.

<p>Showing the 8 major river basins (thick black lines), 31 sub-basins (thin black or gray lines), major rivers (blue lines), 11 proposed canals under India's Interlinking of Rivers Programme interbasin water transfer plan (IBWT; red lines), and the initial local species richness (LSR; grey shading).</p

Average rank (of 130 generations) versus occupancy after each canal link is implemented.

<p>Note log scale of the y axis. Each of the 11 linking steps is represented by one plot. The lower, black line is the rank-occupancy under the no linking step; the solid red line is the resulting occupancy after each link is added under the ‘economic’ linking strategy, and the blue dotted line is the resulting occupancy after each link is added under the ‘ecological’ linking strategy. Each panel is an implementation step, where the canal added under the ecological strategy at a given step is not the same as the canal added in the economic strategy (compare canal implementation in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034170#pone-0034170-g003" target="_blank">Fig. 3</a>).</p

Spatiotemporal visual statistics of aquatic environments in the natural habitats of zebrafish

Abstract Animal sensory systems are tightly adapted to the demands of their environment. In the visual domain, research has shown that many species have circuits and systems that exploit statistical regularities in natural visual signals. The zebrafish is a popular model animal in visual neuroscience, but relatively little quantitative data is available about the visual properties of the aquatic habitats where zebrafish reside, as compared to terrestrial environments. Improving our understanding of the visual demands of the aquatic habitats of zebrafish can enhance the insights about sensory neuroscience yielded by this model system. We analyzed a video dataset of zebrafish habitats captured by a stationary camera and compared this dataset to videos of terrestrial scenes in the same geographic area. Our analysis of the spatiotemporal structure in these videos suggests that zebrafish habitats are characterized by low visual contrast and strong motion when compared to terrestrial environments. Similar to terrestrial environments, zebrafish habitats tended to be dominated by dark contrasts, particularly in the lower visual field. We discuss how these properties of the visual environment can inform the study of zebrafish visual behavior and neural processing and, by extension, can inform our understanding of the vertebrate brain

Plots of the model fits to the data used for the analysis.

<p>Panel A: rank-occupancy for the empirical freshwater fish data (dotted line), neutral model (dashed line; averaged over 120 simulation runs of the rank-occupancy after 130 generations), and the MAXENT-derived rank-occupancy distribution data (solid line). Panel B: relationship between the local species richness (LSR) from the neutral model (y-axis) and the MAXENT-derived distribution data (x-axes). The solid line is the 1∶1 line.</p

Optic flow in the natural habitats of zebrafish supports spatial biases in visual self-motion estimation

Animals benefit from knowing if and how they are moving. Across the animal kingdom, sensory information in the form of optic flow over the visual field is used to estimate self-motion. However, different species exhibit strong spatial biases in how they use optic flow. Here, we show computationally that noisy natural environments favor visual systems that extract spatially biased samples of optic flow when estimating self-motion. The performance associated with these biases, however, depends on interactions between the environment and the animal's brain and behavior. Using the larval zebrafish as a model, we recorded natural optic flow associated with swimming trajectories in the animal's habitat with an omnidirectional camera mounted on a mechanical arm. An analysis of these flow fields suggests that lateral regions of the lower visual field are most informative about swimming speed. This pattern is consistent with the recent findings that zebrafish optomotor responses are preferentially driven by optic flow in the lateral lower visual field, which we extend with behavioral results from a high-resolution spherical arena. Spatial biases in optic-flow sampling are likely pervasive because they are an effective strategy for determining self-motion in noisy natural environments