Age, Growth, Longevity, And Mortality Of Blackcheek Tonguefish, Symphurus Plagiusa (Cynoglossidae : Pleuronectiformes), In Chesapeake Bay, Virginia

Age structure, longevity, and mortality were determined for a population of blackcheek tonguefish, Symphurus plagiusa, in Chesapeake Bay. Blackcheek tonguefish (36-202 mm TL) were randomly collected by means of otter trawl in lower Chesapeake Bay and major Virginia tributaries (James, York, and Rappahannock rivers) from April 1994 through August 1995. Ages were determined by interpreting growth increments on thin transverse sections of sagittal otoliths. Marginal increment analysis showed that a single annulus was formed in June of each year. Blackcheek tonguefish caught during this study reached a maximum age of 5+ years. Growth was rapid during the first year, then slowed rapidly at a time coincident with maturation. We used the following von Bertalanffy growth equations: for males-L-t = 196.5(1- e(-0.285(t + 0.92))); and for females-L-t = 190.6(1 - e(-0.320(t + 0.78))). Von Bertalanffy parameters were not significantly different between sexes. Extrapolated instantaneous mortality rates for a possible seventh year class were 0.73 (Hoenig\u27s equation) and 0.77 (Royce\u27s equation). High estimates of instantaneous total mortality may reflect either loss due to emigration of adults from Chesapeake Bay onto the continental shelf or high natural mortality occurring in this northernmost population. Compared with sympatric pleuronectiforms, blackcheek tonguefish have a relatively high mortality rate, small asymptotic length, and high growth parameter K. Species, such as blackcheek tonguefish, that feature this combination of growth parameters are hypothesized to be better adapted at exploiting seasonally dynamic and highly unpredictable environments, such as those estuarine habitats within Chesapeake Bay

Age, Growth, And Reproduction Of Tautog Tautoga-Onitis (Labridae, Perciformes) From Coastal Waters Of Virginia

Tautog Tautoga onitis are gaining popularity in Virginia\u27s coastal waters as a recreational and food fish. Adult tautog are seasonally abundant on inshore hard-bottom habitats (1-10 m) and inhabit offshore areas (10-75 m) year-round. Juveniles, especially newly-settled recruits, inhabit vegetated areas in shallow water (usually \u3c 1 m). From March 1979 to July 1986, tautog were collected in lower Chesapeake Bay and nearby coastal waters to examine age, growth, and sexual maturation. Age estimates were determined from annular marks on opercle bones: 82% of the fish were age-10 or younger, 18% exceeded age-10, and 1% were age-20 or older. Marginal increment analysis revealed that annuli formed concurrent with a protracted spawning season (April-July). The von Bertalanffy growth equation, derived from back-calculated mean lengths-at-age, was l(t) = 742 [1-e-0.085 (t-1.816)]. Tautog are long-lived (25+ yr) and attain relatively large sizes (672 mm TL) slowly (K for sexes combined = 0.085). Growth rates of both sexes are similar, although males grow slightly faster (K = 0.090 vs. 0.085 for females). Maturity occurs at age-3 in both sexes. Growth rates for tautog from Virginia are similar to those reported nearly 25 years ago for tautog in Rhode Island. Growth rates for tautog are similar to those of other reef fishes, such as snappers and groupers. Habitat restriction, slow growth, great longevity, and increasing popularity by user groups may contribute to over-exploitation of this species in Virginia waters

A systematic revision of Atlantic tonguefishes (Symphurus: cynoglossidae: pleuronectiformes) with a preliminary hypothesis of species group relationships

Four of 29 previously described nominal species of Symphurus are junior synonyms; one sub-species (S. p. plagusia) is accorded full species status (S. tessellatus); two undescribed dwarf species are present in the eastern Atlantic; three new species were found among western Atlantic material; and several Atlantic forms are represented in the eastern Pacific by cognate species. Detailed and expanded descriptions, differential diagnoses, artificial keys and updated ecological information are provided for 29 species occurring in the Atlantic Ocean. Preliminary evidence based upon osteological characters, including interdigitation patterns (ID) of dorsal pterygiophores with neural spines, urohyal shape, caudal skeleton, dentition and other morphological characters, indicates the existence of eight supra-specific lineages among the 66 nominal species of Symphurus. Species groupings are also supported by zoogeographical and ecological distributional patterns. Seven species groups are represented among the Atlantic Symphurus

Seasonal Occurrence And Site-Utilization Patterns Of Adult Tautog, Tautoga Onitis (Labridae), At Manmade And Natural Structures In Lower Chesapeake Bay

Ultrasonic transmitters were surgically implanted into adult tautog (n=27,400-514 mm TL) to document seasonal occurrence and site utilization at four sites situated within known tautog habitat near Cape Charles, Virginia, in lower Chesapeake Bay. Tagged tautog were released at the same sites where originally caught within 2 h of capture. Sites were continuously monitored with automated acoustic receivers between 9 November 1998 and 13 October 1999. Two sites consisted of natural bedform. materials and two sites consisted of manmade materials. Ninety-four percent of tautog (n=15) released in fall 1998 remained inshore during winter at sustained water temperatures of 5-8 degreesC, rather than moved offshore during winter as documented for tautog off New York, Rhode Island, and Massachusetts. Ninety-one percent (n=10) of tautog released in spring 1999 remained inshore during summer when water temperature was 27 degreesC and in the absence of an important food item, blue mussels (Mytilus edulis). These findings conflict with assertions that tautog move to cooler water in summer when water temperatures reach 20 degreesC. Tautog released at natural bedform. sites were detected only at these sites throughout the study. Tautog released at manmade structures also displayed high site-utilization patterns, but several tautog periodically moved 2-10.2 km away from these sites over featureless bottom, a known deterrent to emigration for large temperate labrids in other waters. Benthic communities were similar at manmade sites and natural bedform sites, and movement away from manmade sites may have been influenced by habitat size as well as habitat structure. Understanding temporal and spatial utilization of habitats is an important first step to identifying essential fish habitat and to evaluating and protecting fishery resources within Chesapeake Bay and elsewhere

Reproductive Seasonality, Fecundity, And Spawning Frequency Of Tautog (Tautoga Onitis) In The Lower Chesapeake Bay And Coastal Waters Of Virginia

The tautog, Thutoga onitis (Linnaeus), ranges from Nova Scotia to South Carolina and has become a popular target for recreational and commercial fisheries. Although tautog are a multiple spawning species, reproductive potential, measured as annual fecundity, has not been estimated previously with methods (batch fecundity, spawning frequency) necessary for a species with indeterminate annual fecundity. A total of 960 tautog were collected from the mouth of the Rappahannock River in the lower Chesapeake Bay to 45 kin offshore of Virginia\u27s coastline to investigate tautog reproductive biology in the southern portion of the species range. Tautog did not exhibit a 1:1 sex ratio; 56% were females. Male tautog reached 50% maturity at 218 mm TL, females at 224 mm TL. Tautog spawned from 7 April 1995 to 15 June 1995, at locations from the York River to 45 kin offshore. Batch fecundity estimates ranged from 2800 to 181,200 eggs per spawning for female tautog age 3-9, total length 259516 mm. Mean batch fecundity +/-SEM for female tautog ages 4-6 was 54,243 2472 eggs and 106,256 3837 eggs for females ages 7-9. Spawning frequency was estimated at 1.2 days, resulting in 58 spawning days per female in 1995. Estimates of potential annual fecundity for tautog ages 3-9 ranged from 160,000 to 10,510,000 eggs

Effect of clay and iron sulphate on volatile and water-extractable organic compounds in bamboo biochars

Improved plant disease resistance, seed germination and plant productivity have recently been associated with mineral-enhanced biochars. This has generated interest in characterizing those biochar organic compounds which may contribute to their favorable properties. This study builds on recent physico-chemical characterization of a series of mineral-enhanced bamboo biochars produced between 350 and 550 °C. Here, these biochars are subjected to aqueous extraction followed by liquid chromatography organic carbon detection (LC-OCD) and thermal desorption gas chromatography mass spectrometry (TD-GC/MS). These techniques provide a structural insight into their more bio-available organic compounds and how they vary with pyrolysis temperature. In comparison to neat biochar, their mineral-enhanced composites produce at least three times the water-extractable organic carbon, nitrogen and VOCs, and this increase is further amplified at pyrolysis higher temperatures. However, the biochar carbon fraction that is mobile is low, with total TD-GC/MS compatible VOCs reporting approximately 0.2% and LC-OCD solubles approximately 1–2%. Prior mineral impregnation of bamboo enhances the release of oxygenated compounds including humics and phenolics from its biochars. This increase in mobile oxygenates occurs at higher pyrolysis temperatures despite these minerals catalyzing lignocellulose condensation and carbonization. This anomaly is explained by oxygenates relatively small contribution and the self inerting batch pyrolysis conditions producing different biochar surface and bulk molecular properties. By describing the impact of mineral amendments on the yield and structure of mobile organic compounds that may be released from biochar, this work contributes to our understanding of biochar efficacy in soils

Protein Microarray On-Demand: A Novel Protein Microarray System

We describe a novel, simple and low-cost protein microarray strategy wherein the microarrays are generated by printing expression ready plasmid DNAs onto slides that can be converted into protein arrays on-demand. The printed expression plasmids serve dual purposes as they not only direct the synthesis of the protein of interest; they also serve to capture the newly synthesized proteins through a high affinity DNA-protein interaction. To accomplish this we have exploited the high-affinity binding (∼3–7×10 −13 M) of E. coli Tus protein to Ter, a 20 bp DNA sequence involved in the regulation of E. coli DNA replication. In our system, each protein of interest is synthesized as a Tus fusion protein and each expression construct directing the protein synthesis contains embedded Ter DNA sequence. The embedded Ter sequence functions as a capture reagent for the newly synthesized Tus fusion protein. This “all DNA” microarray can be converted to a protein microarray on-demand without need for any additional capture reagent.

Monitoring and modelling landscape dynamics

International audienceChanges in land cover and land use are among the most pervasive and important sources of recent alterations of the Earth's land surface.This special issue also presents new directions in modelling landscape dynamics. Agent-based models have primarily been used to simulate local land use and land cover changes processes with a focus on decision making (Le 2008; Matthews et al. 2007; Parker et al. 2003; Bousquet and Le Page 2001)