Duermit E.,South Carolina Department of Natural Resources |
Duermit E.,College of Charleston |
Kingsley-Smith P.R.,South Carolina Department of Natural Resources |
North American Journal of Fisheries Management | Year: 2015
Abstract: The practice of claw removal in the fishery for stone crab Menippe spp. can affect fished populations in an atypical way because harvested individuals are not necessarily killed. In all stone crab fisheries, crabs are returned to the water after their claws are harvested with the expectation that claws may be regenerated, thus “renewing” the fishery. The number of legal-sized claws that can be removed from an individual differs (with local regulations) throughout the stone crabs' range. We examined the direct and indirect consequences of removing one and two claws by monitoring mortality and prey consumption in the short term (14 d) and mortality and growth over the long term (11 months). Claw removal induced mortality within days when wound widths were greater than 7 mm, regardless of the number of claws removed. Wound widths created by autotomy were similar to those created by a clean, forced break along the natural fracture plane. These results suggest that direct mortality following claw removal may be low in a two-claw fishery for stone crabs that do not incur large wounds; however, indirect effects that result from altered feeding abilities may be substantial. Stone crabs with one claw removed (the crusher) consumed fewer bivalves than control (intact) crabs, whereas stone crabs with two claws removed did not consume any bivalves but ate fish flesh. Consequently, bivalves, an important prey resource throughout the stone crabs' geographical range, are eliminated from a clawless crab's diet until its claws are regenerated. No stone crabs regenerated a legal-sized claw on the first molt after claw removal, and no stone crabs larger than 104 mm carapace width molted within 11 months. Thus, the long intermolt duration of legal-sized stone crabs and the reduced prey consumption for stone crabs that lost claws indicate that the return to the fishery of previously harvested stone crabs is probably an uncommon occurrence. Received December 17, 2014; accepted June 15, 2015 © 2015, © American Fisheries Society 2015.
Wilber D.H.,HX5 |
Clarke D.G.,HDR |
Alcoba C.M.,U.S. Army |
Gallo J.,U.S. Army
Journal of Sea Research | Year: 2016
The effect of climate variability on flatfish includes not only the effects of warming on sensitive life history stages, but also impacts from more frequent or unseasonal extreme cold temperatures. Cold weather events can affect the overwintering capabilities of flatfish near their low temperature range limits. We examined the responses of two flatfish species, the thin-bodied windowpane (Scophthalmus aquosus) and cold-tolerant winter flounder (Pseudopleuronectes americanus), to variable winter temperatures in a Northwest Atlantic estuary using abundance and size data collected during a monitoring study, the Aquatic Biological Survey, conducted from 2002 to 2010. Winter and spring abundances of small (50 to 120 mm total length) juvenile windowpane were positively correlated with adult densities (spawning stock) and fall temperatures (thermal conditions experienced during post-settlement development for the fall-spawned cohort) of the previous year. Windowpane abundances in the estuary were significantly reduced and the smallest size class was nearly absent after several consecutive years with cold (minimum temperatures < 1. °C) winters. Interannual variation in winter flounder abundances was unrelated to the severity of winter temperatures. A Paulik diagram illustrates strong positive correlations between annual abundances of sequential winter flounder life history stages (egg, larval, Age-1 juvenile, and adult male) within the estuary, reflecting residency within the estuary through their first year of life. Temperature variables representing conditions during winter flounder larval and post-settlement development were not significant factors in multiple regression models exploring factors that affect juvenile abundances. Likewise, densities of predators known to consume winter flounder eggs and/or post-settlement juveniles were not significantly related to interannual variation in winter flounder juvenile abundances. Colder estuarine temperatures through the first year of life were associated with smaller Age-1 winter flounder body size. For example, Age-1 winter flounder developing under conditions that differed by 1.9. °C in mean daily water temperature, averaged 98.7 mm total length (TL) and 123.1 mm TL, for the relatively cold vs. moderate years, respectively. More frequent cold temperature extremes associated with climate variability may negatively impact the overwintering capabilities of some flatfish near their cold temperature range limits, whereas cold-tolerant species may experience reduced growth, which imparts the ecological challenges associated with smaller body size. © 2015 Elsevier B.V.
PubMed | U.S. Army and HX5
Type: | Journal: Environmental toxicology and chemistry | Year: 2017
Insensitive munitions (IMs) are desirable alternatives to historically used formulations, such as 2,4,6-trinitrotoluene (TNT), due to their insensitivity to unintended detonation. The insensitive munition IMX-101 is a mixture of 2,4-dinitroanisole (DNAN), 3-nitro-1,2,4-triazol-5-one (NTO), and nitroguanidine (NQ). Environmental releases of munitions may be from production wastewaters or training; these munitions may be exposed to Ultraviolet light. Therefore, it is useful to understand the relative toxicity of IMX-101 and its constituents both before and after photo-degradation. The intent of the present study was to generate relative hazard information by exposing the standard ecotoxicological model Ceriodaphnia dubia to each IM constituent individually and to IMX-101 before and after the exposure solution was irradiated in a UV photo-reactor. Without photo-degradation, DNAN was more toxic (lethal median concentration, or LC50=43mg/L) than the other two constituents and it contributed predominately to the toxicity of IMX-101 (LC50=206mg/L) based on toxic units. Toxicity was observed only at high levels of NQ (LC50=1174mg/L) and pH-adjusted NTO (LC50=799mg/L). The toxicity of IMX-101 is lower than literature reported values for TNT toxicity. Photo-degradation efficiency was greater at lower IM concentrations. The observed degradation was greatest for NQ (42-99%), which in turn corresponded to the greatest relative increase in toxicity (100- to 1000-fold). More modest percent degradation (4 to 18%) and increases in photo-toxicity (2 to 100-fold) were observed for NTO and DNAN. Photo-degraded NQ products were the predominant source of toxicity of photo-degraded IMX-101. Future work involves research to enable analytical and computational confirmation of the specific degradation compounds inducing the observed photo-enhanced toxicity. This article is protected by copyright. All rights reserved.
Sviatenko L.K.,Dnipropetrovsk National University |
Gorb L.,HX5 |
Hill F.C.,U.S. Army |
Leszczynska D.,Jackson State University |
Leszczynski J.,Jackson State University
Journal of Computational Chemistry | Year: 2016
Reduction and oxidation (redox) reactions are widely used for removal of nitrocompounds from contaminated soil and water. Structures and redox properties for complexes of nitrocompounds, such as 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), 2,4-dinitroanisole (DNAN), and 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO), with common inorganic ions (Na+, Cl-, NO3-) were investigated at the SMD(Pauling)/PCM(Pauling)/MPWB1K/TZVP level of theory. Atoms in molecules (AIM) theory was applied to analyze the topological properties of the bond critical points involved in the interactions between the nitrocompounds and the ions. Topological analyses show that intermolecular interactions of the types O(N)...Na+, C-H...Cl-( ONO2-), and C...Cl-( ONO2-) may be discussed as noncovalent closed-shell interactions, while N-H···Cl-( ONO2-) hydrogen bonds are partially covalent in nature. Complexation causes significant decrease of redox activity of the nitrocompounds. Analysis of the reduction potentials of the complexes obtained through application of the Pourbaix diagram of an iron/water system revealed that sodium complexes of NTO might be reduced by metallic iron. © 2016 Wiley Periodicals, Inc.