Larval Development of Pagurus longicarpus Say Reared in the Laboratory, I. Description of Larval Instars

Thompson ( 1903) described from the plankton four zoeae and a megalopa which he ascribed to Pag11ru.s longicarpus. Although his verbal description of the external anatomy is incomplete, his figures are adequate to identify accurately the species with which he was working. His description of the internal anatomy is the most complete study available for any decapod larva. He indicated that some larvae of P. annulipes were included in his study material but that he was unable todifferentiate the two species. MacDonald, Pike, and Willamson ( 1957) and Pike and Williamson ( 1959, 1960) described the larvae of several British and Mediterannean Pagurus species from carefully constructed plankton series. They were able to distinguish three types of larvae in this genus, based on 12 larval characteristics (several of which were composites of two characteristics), suggesting that the genus Pagurus may be polyphyletic, but no division of the genus was attempted for lack of adult characteristics supporting the larval data. Larvae of several addi tional Pagur11s species have been described from culture experiments by Coffin ( 1958, 1960), Hart ( 1937), Provenzano and Rice ( 1964) and Shenoy ( 1967). In addition, P. bernhardus has been cultured by Bookhout (1964) and A. Le Roux (personal communication) and shown to agree in all essentials with the description given by MacDonald et al. ( 1957). This paper deals with the external anatomy of P. longicarpus larvae reared in the laboratory. It is clearly demonstrated that Thompson ( 1903) attributed his larvae to the wrong species and a suggestion is made as to the correct identity of his larvae

Acute Toxicity Potential of Chlorination in Estuarine Waters

Two primary uses of chlorination in estuarine systems are disinfection of sewage effluent and fouling control in condensor tubes of electric power generating plants. The intent in both uses is to apply sufficient chlorine to kill certain target organisms. At the same time, however, efforts are made to control both the application rate and effluent release so that non-target species in the receiving waters are not affected. To accomplish such control, the effluent is usually retained, which permits the decay of the residual chlorine and rapid dilution with ambient water to reduce further the residual. The residual concentration continues to decay in the ambient water through a series of reactions outlined in Dr. Helz\u27s paper. If all goes well, no adverse impacts can be expected in the receiving waters. However, ·at least two disquieting instances of chlorination\u27s possible impact in the Chesapeake Bay have been observed.https://scholarworks.wm.edu/vimsbooks/1172/thumbnail.jp

Larval Development of Pagurus longicarpus Say Reared in the Laboratory. II. Effects of Reduced Salinity on Larval Development

Temperature and salinity define a set of conditions within which planktonic organisms can survive and develop. Thorson ( 1946) described the restriction of some meroplankters to Kattegat water in the Oresund which was presumed to be based on either a temperature, or a salinity discontinuity or both. Bary ( 1963a, b, c) , in an extensive study of North Atlantic plankton, clearly demonstrated a relationship between zooplankton distribution and temperature-salinity distribution. Banse ( 1956) observed the distribution of polychaete and echinoderm larvae with respect to various water masses in Kiel Bay. He concluded that these larvae were restricted to their Gebirtswasser the temperature-salinity characteristics of these water masses. In a subsequent paper ( 1959) he described a similar situation for copepods. ( ...

Larval Development of Pagurus longicarpus Say Reared in the Laboratory. III. Behavioral Responses to Salinity Discontinuities

Survival rate, although commonly used as an index of an organism\u27s ability to meet a given environmental challenge ( Costlow, Bookhuout, and Monroe, 1960, 1962, 1966 ; Roberts,1971), is a rather crude estimate of the ability of an organism to adapt to its environment. Behavioral responses associated with the maintenance of an animal in its optimial environment are more suitable measures of adaptability (Shelford, 1915 ) . Orientative behavior reflects, at least in part, flue integration of an animal\u27s various adaptive physiological changes in metabolism, reproduction, hormonal balance, etc., to challenges of the external milieu. Responses of various zoophankfers to salinity discontinuities were first studied by Harder ( 1952a, 1952b, 1954, 1957, 1968) . The ability to detect and avoid waters of reduced salinity has now been demonstrated experimentally for several meroplankters as well as holoplankters. A response to salinity discontinuities has been demonstrated in Mercenaria mercenania trochophores (Turner and George, 1955 ) , Phyllodoce trochopluores ( Lyster, 1965) , some copepods and the zoeal instars of Pisidia longicornis (Lance, 1962) , and Zoea I of Homarus amenicanus ( Scarratt and Raine, 1967). In the present study, the response of Pagurus longicarpus zoeal instars to salinity discontinuities of different magmuitudes was examined. The avoidance behavior was described and quantified. The interaction effect of developmental age and magnitude of the discontinuity on the response was examined. Further an attempt was made to determine if the receptor(s) is localized on certain structures

How Can We Best Test The Effects Of Pollutants And Changes On The Animals And Plants Of Chesapeake Bay?

The animals and plants of the Bay, and the processes in which they are involved, are the basis for almost every use and desirable quality of the Bay. They provide both commercial and recreational fisheries, assimilate some quantities of wastes, contribute to esthetic quality, provide a favorable environment for many birds and mammals and feed all of the species which are used by man. However, the biota are directly or indirectly affected by many human activities - by maritime transport, recreational activities, agricultural production, waste discharges, domestic development, engineering activity, and other land-based activities. Therefore, the ultimate and most important question to be considered in evaluating any new pollutant or proposed environmental modification is - What effect will it have on the biota?https://scholarworks.wm.edu/vimsbooks/1175/thumbnail.jp

Present and historical environmental survey of Broad Creek, Norfolk, Virginia : with special reference to biotic communities and the effects of alum discharge

Sediment samples collected from 15 stations in Broad Creek, a tributary of the Eastern Branch Elizabith River (Norfolk, VA) were analyzed for various sedimentary and stratigraphic features to determine the distribution of alum sludge (aluminum as the hydroxide) resulting from discharge from the Moore\u27s Bridge Water Treatment Plant. Enrichment of surface sediments with aluminum was evident at all stations, with decreasing concentration as one progresses downstream from the Moore\u27s Bridge plant discharge. At the bottom of the cores, aluminum enrichment was not observed. With the exception of the aluminum enrichment in the surface layers, the sediments appear typical of tidal freshwater-estuarine transition zones

Chemical and Toxicological Characterization of the Upper York River, Virginia The Mattaponi and Pamunkey Rivers

This study describes the most extensive effort to characterize the chemistry, toxicology and community of the sediments of the Mattaponi and Pamunkey Rivers. This was accomplished using a study design modified to expand the number of stations occupied by reducing the cost of analyses by compositing replicate samples collected from each study site rather than performing toxicity tests on these samples individually. In previous studies, the variability in field replicate samples was equivalent to the variability in laboratory replicates. This design has long been used to analyze samples for various chemical contaminants as a cost savings endeavor. More ...

Preliminary evaluation of water quality in tidal creeks of Virginia\u27s Eastern Shore in relation to vegetable cultivation

In response to concerns raised about the impacts of vegetable cultivation using plastic ground covers on water quality, we have initiated a broad-scale, systematic study of water quality in seaside tidal creeks of Virginia\u27 s Eastern Shore. Our objective was to determine if acute toxicity associated with heavy metals or pesticides was more prevalent in tidal creeks with drainage areas which include this agricultural practice than in those which do not. Though such correlations do not confirm cause and effect, they may serve as the basis for future, more targeted investigations and for some immediate changes in land management practices which, regardless of the specific cause, are likely to produce some remediation. Eleven study sites, located in six different watersheds, were selected to evaluate acute toxicity (from heavy metals and organic pesticides. Land use patterns and acreage within each watershed was determined from aerial photographs. The amount of vegetable plasti-culture in the watersheds of the study sites ranged from 0-13% of total acreage. An assay for heavy metals, based upon enzyme inhibition in a bacterial strain, was used to determine if up to seven metals (including copper) were present at acutely toxic levels. Both water samples and aqueous extracts of sediment samples were tested. A continuous series of 96 hr in situ bioassays using the grass shrimp, Palaemonetes pugio, were conducted from Aug. I, 1996 - Sept. 22, 1996 at each station to assay for toxicity from organic pesticides. Grass shrimp are known to be quite sensitive to insecticides and the in situ bioassay approach provides a continuous means of monitoring for toxic events