Automatic identification and enumeration of algae

A good understanding of the population dynamics of algal communities is vital in many ecological and pollution studies of freshwater and oceanic systems. Present methods require manual counting and identification of algae and can take up to 90 min to obtain a statistically reliable count on a complex population. Several alternative techniques to accelerate the process have been tried on marine samples but none have been completely successful because insufficient effort has been put into verifying the technique before field trials. The objective of the present study has been to assess the potential of in vivo fluorescence of algal pigments as a means of automatically identifying algae. For this work total fluorescence spectroscopy was chosen as the observation technique

An analogue of Ryser's Theorem for partial Sudoku squares

In 1956 Ryser gave a necessary and sufficient condition for a partial latin rectangle to be completable to a latin square. In 1990 Hilton and Johnson showed that Ryser's condition could be reformulated in terms of Hall's Condition for partial latin squares. Thus Ryser's Theorem can be interpreted as saying that any partial latin rectangle $R$ can be completed if and only if $R$ satisfies Hall's Condition for partial latin squares. We define Hall's Condition for partial Sudoku squares and show that Hall's Condition for partial Sudoku squares gives a criterion for the completion of partial Sudoku rectangles that is both necessary and sufficient. In the particular case where $n=pq$, $p|r$, $q|s$, the result is especially simple, as we show that any $r \times s$ partial $(p,q)$-Sudoku rectangle can be completed (no further condition being necessary).Comment: 19 pages, 10 figure

It’s raining sturgeons: a likely occurrence of avian predation or scavenging of Atlantic Sturgeon (Acipenser oxyrinchus Mitchell, 1815)

Predation on the federally-endangered Atlantic Sturgeon (Acipenser oxyrinchus), and sturgeons generally is understudied. Most predation is presumed to occur on eggs and larvae, and bethe result of interactions with other aquatic organisms, primarily other fishes. Predation on larger juvenile sturgeon by terrestrial and avian predators remains largely unknown. Here we document the recovery of a juvenile Atlantic Sturgeon carcass (512 mm total length) approximately 120 m inland from the shore of the York River in Gloucester County, Virginia. This individual showed signs of predation by a bird of prey, most likely an Osprey (Pandion haliaetus), although a Bald Eagle (Haliaeetus leucocephalus) cannot be ruled out, as they are also residents in this area. The purpose of this note is to document this occurrence and suggest further study of predation on Atlantic Sturgeon in the Chesapeake Bay

Temperature selectivity and movement patterns of speckled trout

Speckled trout (Cynoscion nebulosus) is the focus of an important recreational fishery in the southeastern United States. Speckled trout in Virginia has been cited as both a transitional population and as a mostly non-migratory population. The degree of residency is important to understand for the effective management of the species. Management of speckled trout has also been marred by cold-stun events which can kill a significant portion of the stock and have detrimental localized effects. Virginia is the northern extent of speckled trout populations and is the most likely portion of its range to experience cold-stun events. Virginia water temperatures can reach 0 °C during some winters, well below lethal temperatures for speckled trout. The primary objective of this project was to provide managers and recreational fishermen with information regarding speckled trout movements. more..

Monitoring Relative Abundance of American Shad in Virginia Rivers 2009 Annual Report

Concern about the decline in landings of American shad (Alosa sapidissima) along the Atlantic coast prompted the development of an interstate fisheries management plan (FMP) under the auspices of the Atlantic States Marine Fisheries Management Program (ASMFC 1999). Legislation enables imposition of federal sanctions on fishing in those states that fail to comply with the FMP. To be in compliance, coastal states are required to implement and maintain fishery-dependent and fishery-independent monitoring programs as specified by the FMP. For Virginia, these requirements include spawning stock assessments, the collection of biological data on the spawning run (e.g., age-structure, sex ratio, and spawning history), estimation of total mortality, indices of juvenile abundance, biological characterization of permitted by-catch and evaluation of restoration programs by detection and enumeration of hatchery-released fish. This annual report documents continued compliance with Federal law. Since 1998, scientists at the Virginia Institute of Marine Science have monitored the spawning run of American shad in the James, York and Rappahannock rivers. The information resulting from this program is reported annually to the ASMFC, has formed the basis for a significant number of technical papers published in the professional literature, formed the basis for a recent coast-wide stock assessment and peer review for American shad (ASMFC 2007a, 2007b) and is contributing substantially to our understanding of the status and conservation of this important species. A number of individuals make significant contributions to the monitoring program and the preparation of this report. Commercial fishermen Tony Kellum, Raymond Kellum, Marc Brown and Jamie Sanders construct, set, and fish the sampling gear and offer helpful advice. They have participated in the sampling program since its beginning in 1998. Their contributions as authors of historic log books of commercial catches during the 1980s and as expert shad fishermen are essential elements of the monitoring program. We also extend our appreciation to several commercial fishers for their cooperation in our studies of by-catch of American Shad. In 2009, these individuals include: Kenneth Heath, Joseph Hinson, Demtri Hionis, George Trice, Robert Weagley, and Charles Williams. In 2009, the staff and students of the Virginia Institute of Marine Science who participated in the program were: B. Watkins, P. Crewe, A. Rhea, and R. Harris. Their dedication, consistent attention to detail and hard work in the field and in the laboratory are appreciated. B. Watkins determined ages of fish. B. Watkins and A. Rhea determined hatchery origins of fish. Fish products from the sentinel fishery are donated to the Food Bank of Newport News, Virginia. We offer thanks to the Hunters for the Hungry (Virginia Hunters Who Care) organization for their assistance

M dwarf stars in the light of (future) exoplanet searches

We present a brief overview of a splinter session on M dwarf stars as planet hosts that was organized as part of the Cool Stars 17 conference. The session was devoted to reviewing our current knowledge of M dwarf stars and exoplanets in order to prepare for current and future exoplanet searches focusing in low mass stars. We review the observational and theoretical challenges to characterize M dwarf stars and the importance of accurate fundamental parameters for the proper characterization of their exoplanets and our understanding on planet formation.Comment: 4 pages, 1 figure. Summary of the splinter session "M dwarf stars in the light of (future) exoplanet searches" held at the 17th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, June 28th 2012, Barcelona, Spain. Submitted for publication in Astronomische Nachrichten - Astronomical Notes (AN) 334, Issue 1-2, Eds Klaus Strassmeier and Mercedes L\'opez-Morale

Seasonal Distributions and Movements of Longnose Gar (Lepisosteus osseus) within the York River System, Virginia

The seasonal movements of Lepisosteus osseus (Longnose Gar) are largely unknown. The goal of this project was to characterize spawning movements and seasonal distributions by using acoustic tagging methods and examining historical catch records from a trawl survey. This is the first time that movements have been studied for an estuarine population of Longnose Gar. Two individuals moved greater minimum distances (69 and 74 km) than found in the only other report on movement in this species. Spawning-ground residency time, collected from two tagged Longnose Gar, was approximately one month, and tidal periodicity was observed for one of the two fish. Data from a fisheries independent trawl survey were used to examine seasonal catch distributions in Longnose Gar and represents the first report of winter distributions for this species. Winter locations occurred both alongshore and mid-channel, and the distributions were similar to those in the summer and fal

Patterns of Hatchery-Produced Returns of American Shad in the James River, Virginia

American Shad Alosa sapidissima is an anadromous clupeid that once supported a robust fishery but has declined drastically throughout its native range due to overfishing, dam proliferation, and poor water quality. A hatchery program on the James River in Virginia was introduced in 1992 to support the recovery of stocks. Following a moratorium of the fishery enacted in 1994, a fisheries-independent survey was initiated in 1998 to monitor the population recovery efforts and status of American Shad stocks in Virginia. This paper examined 22 years of monitoring data for the James River and determined the effect of hatchery inputs on the James River stock of American Shad. The spawning stock index increased from 2.57 in 1998 to a peak of 9.33 in 2003 but has generally been declining since and has been at very low levels in most recent years. The hatchery prevalence for female American Shad (i.e., the percentage of fish derived from the hatchery) ranged between 3.6% and 60.5%. Years with higher spawning stock index values were significantly correlated to higher percentages of hatchery fish returning to spawn. The stock–recruitment relationship was best explained by the Ricker model, which had the lowest residual standard error and Akaike information criterion value. A threshold level of hatchery-released individuals (approximately 4 million larvae) was necessary to achieve the highest numbers of returning spawners, but stocking above 7 million larvae correlated with declining returns. Long-term monitoring of the James River American Shad spawning population allowed for the critical examination of the contribution of hatchery individuals to the yearly spawning run and the relative success rate of each hatchery year-class. From these data, we consider that the James River spawning stock of American Shad was dependent upon hatchery inputs, with ideal hatchery returns occurring during years of moderate levels of hatchery stocking