[en] Tributyltin (TBT) was detected in all 24 surface sediment (top 2 cm) samples collected from Coddington Cove, Newport, RI. TBT surface sediment concentrations ranged from 32 to 372 ng Sn/g with a mean concentration of 146 ng Sn/g. Analyses of selected core sections detected TBT in at least the top 18 cm at all 7 stations where cores were collected. No consistent TBT concentration trends with depth for these cores suggest mixing is an important process in the sediment column. In one core (station 28), TBT was found in the 76-86 cm section at a concentration of 141 ng Sn/g; thus sediments are a significant sink for TBT. However, sediment mixing processes can enhance releases of bioavailable TBT. Mussels, clams and fish from Coddington Cove contain TBT at concentrations ranging from 9.2 to 977 ng Sn/g. TBT concentrations in lobsters were below the detection limit (<6 ng Sn/g). Based on available screening criteria, TBT concentrations in Coddington Cove sediment is likely to be having an adverse effect on the biota at some locations. - TBT is likely to continue to be bioavailable for many years

[en] We discuss inverse problem results for problems involving the estimation of probability distributions using aggregate data for growth in populations. We begin with a mathematical model describing variability in the early growth process of size-structured shrimp populations and discuss a computational methodology for the design of experiments to validate the model and estimate the growth-rate distributions in shrimp populations. Parameter-estimation findings using experimental data from experiments so designed for shrimp populations cultivated at Advanced BioNutrition Corporation are presented, illustrating the usefulness of mathematical and statistical modeling in understanding the uncertainty in the growth dynamics of such populations

No abstract available

[en] This work was aimed at evaluating the gill carbonic anhydrase (CA) activity of the estuarine crab Chasmagnathus granulata exposed in vivo to cadmium, at different salinities. The in vivo effect of the specific inhibitor acetazolamide (AZ) was also assayed. Besides, the inhibition of CA activity by different heavy metals (cadmium, copper, zinc) and AZ were evaluated under in vitro conditions. For the in vivo assays, adult males were acclimated to salinities of 2.5 or 30per thousand. The corresponding 96-h LC₅₀ of cadmium was 2.69 mg l^-150 mg l^-1 at 30per thousand. Cadmium only caused a significant lower CA activity than control at 2.5per thousand. EC₅₀ for CA inhibition was estimated to be 1.59 mg l^-1 at 2.5per thousand. Statistical differences in Na⁺ hemolymphatic levels (P<0.05) were only detected at 2.5per thousand, between 0 and 1.25 mg l^-1 of cadmium, but no statistical differences were observed for Cl^- levels at any assayed salinity. As CA inhibition registered at 2.5per thousand was followed by only changes in Na⁺ concentration, it is likely that cadmium exposure could differentially affect ions permeability, among others factors. The concentrations that inhibited in vitro 50% of enzymatic activity (IC₅₀) were 2.15x10^-5, 1.62x10^-5, 3.75x10^-6 and 4.4x10^-10 M for cadmium, copper, zinc and AZ, respectively. The comparison with IC₅₀ values of other aquatic species, indicates a higher CA sensitivity for C. granulata to pollutants. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

[en] An electronic circuit intended to simulate the nonlinear dynamics of a simplified 3-cell model of the pyloric central pattern generator in California spiny lobster stomato gastric ganglion is presented. The model employs the synaptic phase locked loop (SPLL) concept where the frequency of oscillations of a postsynaptic cell is mainly controlled by the synaptic current which depends on the phase shift between the oscillations. The theoretical study showed that the system has a stable steady state with correct phase shifts between the oscillations and that this regime is stable when the frequency of the pacemaker cell is varied over a wide range. The main bifurcations in the system were studied analytically, in computer simulations, and in experiments with the electronic circuit. The experimental measurements are in good agreement with the expectations of the theoretical model

[en] Aquaculture industry is a spearhead industry with great export potential including white spot cardinal shrimp farming. However, shrimp farming is a production industry with capable of high efficiency but also risky due to problems of shrimp pond water pollution and disease problems on shrimp. In this report, we present some results of the application of rare earth elements in the management and treatment of shrimp pond water at Thach Hai Fisheries Service Company, Thach Hai commune, Thach Ha district, Ha Tinh province. The results of the application on ponds with area of 1500- 2000 m² show that: rare earth elements are capable of stabilizing pH of pond water, reducing harmful gas emissions, eliminating toxic algaes, creating favorable conditions for developing of beneficial algaes, provide trace elements necessary for shrimp cultural, reduce the cost of chemicals to treat pond water, reduce water resource costs, reduce spending food costs.... and allows significant economic efficiency gains compared to control ponds that do not use rare earth elements. (author)

[en] Windu lobster is famous due to the taste and had a good market for export commodity.This experiment was conducted to study the bacterial contamination on windu lobster in an attempt to improve the hygienic quality of lobster produced in Indonesia. Windu lobster were irradiated with the dose 0, 2, 4, 6, 8 and 10 kGy at a dose rate of 5.6 kGy. Parameters measured were total aerob bacteria, coliforms, Escherichia coli and Salmonella. The colour, odor, texture and taste were evaluated immediately after irradiation. The results showed that total aerob bacteria were decreased 3 log cycles after irradiated at 6 kGy, while coliform bacteria and E. coli were decreased 2 log cycles each at 4 kGy, respectively. No Salmonella was detected in all samples observed. In general, irradiation at 4 kGy was sufficient to improve the hygienic condition without affecting their organoleptic properties

[en] For a variety of toxic substances, brine shrimp larvae (Artemia salina) are usually used as a simple bioassay method and it is also applied for natural product research. The brine shrimp larvae (nauplii) are obtained by natural hatching method from Artemia cysts. By using the larvae, the results from these experiments lead to the lethal dose, LD₅₀ values of extracts of selected medicinal plants. Activities of a broad range of plant extracts are manifested as toxicity to the brine shrimp. Screening results with six plant extracts are compared with pure caffeine. This method is rapid, reliable, inexpensive and convenient. (author)

No abstract available

[en] To study the mechanical principles and fluid dynamics of ultrafast power-amplified systems, we built Ninjabot, a physical model of the extremely fast mantis shrimp (Stomatopoda). Ninjabot rotates a to-scale appendage within the environmental conditions and close to the kinematic range of mantis shrimp's rotating strike. Ninjabot is an adjustable mechanism that can repeatedly vary independent properties relevant to fast aquatic motions to help isolate their individual effects. Despite exceeding the kinematics of previously published biomimetic jumpers and reaching speeds in excess of 25 m s"−"1 at accelerations of 3.2 × 10"4 m s"−"2, Ninjabot can still be outstripped by the fastest mantis shrimp, Gonodactylus smithii, measured for the first time in this study. G. smithii reached 30 m s"−"1 at accelerations of 1.5 × 10"5 m s"−"2. While mantis shrimp produce cavitation upon impact with their prey, they do not cavitate during the forward portion of their strike despite their extreme speeds. In order to determine how closely to match Ninjabot and mantis shrimp kinematics to capture this cavitation behavior, we used Ninjabot to produce strikes of varying kinematics and to measure cavitation presence or absence. Using Akaike Information Criterion to compare statistical models that correlated cavitation with a variety of kinematic properties, we found that in rotating and accelerating biological conditions, cavitation inception is best explained only by maximum linear velocity. (paper)