High male reproductive success in a low-density Antarctic fur seal (Arctocephalus gazella) breeding colony

Understanding how population density influences mating systems may lead to important insights into the plasticity of breeding behavior, but few natural systems allow for such studies. Antarctic fur seals (Arctocephalus gazella) provide an interesting model system because they breed in colonies of varying densities. Previous studies have largely focused on a high-density site at Bird Island, South Georgia. Here, 13 highly polymorphic microsatellite loci were used to conduct a genetic analysis of a low-density breeding colony of this species at Livingston Island, approximately 1,600 km south of South Georgia. The majority of adults seen ashore (n?=?54) were sampled together with every pup born (n?=?97) over four consecutive years. Paternities were confidently assigned for 34 out of the 97 pups. Two out of 23 sampled males accounted for the paternity of 28 % of all pups sampled during the study and 82 % of the pups with an assigned father. Moreover, a full likelihood pedigree inference method assigned a further eight paternities to a single unsampled male seal that is inferred to have held a territory during the season before the study began. The most successful males in our study easily surpassed the previous record for the total number of pups sired per male seal for the species. Furthermore, we identified two triads of full siblings implying that their parents remated in three consecutive years. These findings suggest that territorial male fur seals may achieve greater success in monopolizing access to breeding females when population density is relatively low.     

Model selection criteria for overdispersed data and their application to the characterization of a host-parasite relationship

In the statistical modeling of a biological or ecological phenomenon, selecting an optimal model among a collection of candidates is a critical issue. To identify an optimal candidate model, a number of model selection criteria have been developed and investigated based on estimating Kullback’s (Information theory and statistics. Dover, Mineola, 1968) directed or symmetric divergence. Criteria that target the directed divergence include the Akaike (2nd international symposium on information theory. Akadémia Kiadó, Budapest, Hungary, pp 267–281, 1973, IEEE Trans Autom Control AC 19:716–723, 1974) information criterion, AIC, and the “corrected” Akaike information criterion (Hurvich and Tsai in Biometrika 76:297–307, 1989), AICc; criteria that target the symmetric divergence include the Kullback information criterion, KIC, and the “corrected” Kullback information criterion, KICc (Cavanaugh in Stat Probab Lett 42:333–343, 1999; Aust N Z J Stat 46:257–274, 2004). For overdispersed count data, simple modifications of AIC and AICc have been increasingly utilized: specifically, the quasi Akaike information criterion, QAIC, and its corrected version, QAICc (Lebreton et al. in Ecol Monogr 62(1):67–118 1992). In this paper, we propose analogues of QAIC and QAICc based on estimating the symmetric as opposed to the directed divergence: QKIC and QKICc. We evaluate the selection performance of AIC, AICc, QAIC, QAICc, KIC, KICc, QKIC, and QKICc in a simulation study, and illustrate their practical utility in an ecological application. In our application, we use the criteria to formulate statistical models of the tick (Dermacentor variabilis) load on a white-footed mouse (Peromyscus leucopus) in northern Missouri.     

Numerical modelling of horizontal sediment-laden jets

Sediment-laden turbulent flows are commonly encountered in natural and engineered environments. It is well known that turbulence generates fluctuations to the particle motion, resulting in modulation of the particle settling velocity. A novel stochastic particle tracking model is developed to predict the particle settling out and deposition from a sediment-laden jet. Particle velocity fluctuations in the jet flow are modelled from a Lagrangian velocity autocorrelation function that incorporates the physical mechanism leading to a reduction of settling velocity. The model is first applied to study the settling velocity modulation in a homogeneous turbulence field. Consistent with basic experiments using grid-generated turbulence and computational fluid dynamics (CFD) calculations, the model predicts that the apparent settling velocity can be reduced by as much as 30 % of the stillwater settling velocity. Using analytical solution for the jet mean flow and semi-empirical RMS turbulent velocity fluctuation and dissipation rate profiles derived from CFD predictions, model predictions of the sediment deposition and cross-sectional concentration profiles of horizontal sediment-laden jets are in excellent agreement with data. Unlike CFD calculations of sediment fall out and deposition from a jet flow, the present method does not require any a priori adjustment of particle settling velocity.     

Effect of curacron toxicity on the total serum protein content of Cyprinus carpio

An experiment was conducted on freshwater fish Cyprinus carpio to study the effect of the pesticide curacron on total serum protein. Curacron is an organophosphate pesticide and used by the farmers to protect their crops. This pesticide reaches the aquatic ecosystem by direct or indirect means and affects aquatic fauna. LC50 for curacron for C. carpio was calculated by the log-dose/probit regression line method and found to be 0.38?ppm at 96?h. Three sub-lethal concentrations (0.1, 0.01, and 0.001?mL?L^?1) were selected to expose the fish for 1, 7, 14, and 21days. Changes in total serum protein were observed at all pesticide concentrations and exposure periods. Total serum protein was decreased from control. At 1 and 7 days, the decrease was quantitative at all concentrations, while at 14 and 21 days, the fall was significant at all concentrations. Hence, human population may be at risk by consuming these contaminated fish.     

The effect of limiting nutrient on metal toxicity to selenastrum capricornutum

Metal toxicity on selenastrum capricornutum were examined by batch culture and chemostat culture system. EC₅₀ values under nutrient‐limited condition and saturated condition were compared. The two EC_5Os differed by a factor of 10.6 for Cd in batch test, and differed by a factor of 6.5 in continuous test. Both batch and continuous test results indicate that inhibition on algal growth is more severe under nutrient‐limited conditions compared to that under near saturation conditions.

Strong correlation, as characterized by the correlation coefficient ρ, were found between the activation level (nutrient requirement) and the tolerance of microorganisms to the toxicant. ρ is equal to 0.9 for the case of Cd in batch test and 0.6 in continuous test. The theory in this study provides generally good estimations to the dose‐response relationship at limiting nutrient conditions. The study indicate that nutrient conditions constitute an important factor in algal toxicity tests.     

Pah characteristics in ambient air within a steel industrial complex

Ambient air samples at ten sites in an iron and steel industrial complex were collected from June to December for analyzing polycyclic aromatic hydrocarbons (PAHs). Sixteen species of PAH components in air samples were identified. The results indicate that both gaseous phase and particle‐bound PAHs at the top of the cokemaking plants are unusually high. The profiles of particle‐bound PAHs indicate that the predominant species at the top of, the coke oven batteries are those of high molecular weight components. The major components of particle‐bound PAHs at sampling sites near the fenceline, however, include the medium molecular weight components. The PAH profiles of air samples within the industrial complex show a strong similarity to those of cokemaking plant samples. The concentrations and the specific content of benzo(a)pyrene in the iron and steel industrial complex are higher than those values measured in urban area, petrochemical industry park, and open‐air burning area.     

Effects of the Ellagic acid on the N‐Acetyltransferase activity and Acetylation of 2‐aminofluorene in the rat

The effects of the ellagic acid on the in vitro and in vivo acetylation of 2‐aminofluorene were investigated in male Sprague‐Dawley rats. For in vitro examination, cytosols with or without ellagic acid co‐treatment showed different percentage of 2‐aminofluorene acetylation. For in vivo examination, pre‐treatment of male rats with ellagic acid (10 mg/kg) 24h prior to the administration of 2‐aminofluorene (50 mg/kg) resulted in a 26% and 29%, respectively, decrease in the urinary and fecal recovery of N‐acetyl‐2‐aminofluorene, and a 37% decrease in the metabolic clearance of 2‐aminofluorene to N‐acetyl‐2‐aminofluorene. This is the first demonstration that ellagic acid decrease the N‐acetylation of carcinogens in vitro and in vivo.     

Possible health impacts of naturally occurring uptake of aristolochic acids by maize and cucumber roots: links to the etiology of endemic (Balkan) nephropathy

Aristolochic acids (AAs) are nephrotoxic and carcinogenic derivatives found in several Aristolochia species. To date, the toxicity of AAs has been inferred only from the effects observed in patients suffering from a kidney disease called “aristolochic acid nephropathy” (AAN, formerly known as “Chinese herbs nephropathy”). More recently, the chronic poisoning with Aristolochia seeds has been considered to be the main cause of Balkan endemic nephropathy, another form of chronic renal failure resembling AAN. So far, it was assumed that AAs can enter the human food chain only through ethnobotanical use (intentional or accidental) of herbs containing self-produced AAs. We hypothesized that the roots of some crops growing in fields where Aristolochia species grew over several seasons may take up certain amounts of AAs from the soil, and thus become a secondary source of food poisoning. To verify this possibility, maize plant (Zea mays) and cucumber (Cucumis sativus) were used as a model to substantiate the possible significance of naturally occurring AAs’ root uptake in food chain contamination. This study showed that the roots of maize plant and cucumber are capable of absorbing AAs from nutrient solution, consequently producing strong peaks on ultraviolet HPLC chromatograms of plant extracts. This uptake resulted in even higher concentrations of AAs in the roots compared to the nutrient solutions. To further validate the measurement of AA content in the root material, we also measured their concentrations in nutrient solutions before and after the plant treatment. Decreased concentrations of both AAI and AAII were found in nutrient solutions after plant growth. During this short-term experiment, there were much lower concentrations of AAs in the leaves than in the roots. The question is whether these plants are capable of transferring significant amounts of AAs from the roots into edible parts of the plant during prolonged experiments.     

Lead-210 and Beryllium-7 in the Aerosol Particles Around Taiwan Off-Shore Areas

Abstract

Distributions of ²¹⁰Pb and ⁷Be in the aerosol particles of different size fractions were measured around Taiwan offshore areas from October, 1994 to October, 1995. the size distribution and abundance of the aerosol particles showed both spatial and temporal variations. the particle concentrations off northwestern Taiwan were more than twice as those off northeastern Taiwan both in November and March, and the values were much higher in November than in March for both areas. the measured particle concentrations, except for one sample with an unusually high value, ranged from 10 to 83 μOgm ^?3 in the study areas. the ²¹⁰Pb concentrations in the aerosol particles filtered from the air mass varied between 20 × 10^?3 and 72 × 10^?3 dpm m^?3 (1dpm = 0.45 pCi). the ²¹⁰Pb concentrations in the area off southwestern Taiwan appeared somewhat higher than in other areas and were probably contributed by the land air from Taiwan which contains higher ²¹⁰Pb in winter. the ²¹⁰Pb concentrations off northern Taiwan were low in November when the aerosol concentrations were high, but they were high in March when the aerosol concentrations were low.

Based on the ⁷Be monitoring records of 20 years on the aerosol particles of the island by the Taiwan Radiation Monitoring Center, the mean settling rate averaged 0.91, 0.79 and 0.68 cm s^?1, respectively, in northern, central and southern Taiwan. with these values and the ²¹⁰Pb concentrations in the aerosols, the ²¹⁰Pb flux was determined to be between 0.58 and 2.30 dpm cm^?2y^?1, with an average of 1.19 dpm cm^?2y^?1. Excluding the highest value due to its extremely high ²¹⁰Pb and aerosol concentrations, the average is reduced to 1.05 dpm cm^?2y^?1. the activity median diameters (AMD) for ²¹⁰Pb in the study areas were between 0.69 and < 0.49 μM with a mean of 0.5 öm based on ²¹⁰Pb distributions in different particle size fractions. Thus, ²¹⁰Pb was preferentially adsorbed on to the submicron particles. ⁷Be in the study areas showed a good correlation with ²¹⁰Pb in total activity although the two nucides had different sources.     

Recreational diving impacts and the use of pre-dive briefings as a management strategy on Florida coral reefs

Ecotourism often is promoted as an ecologically sustainable activity, but some ecotourism activities negatively impact coastal ecosystems. Impacts of intensive diving tourism on coral reefs remain poorly understood, especially in the Florida Keys. We determined patterns of recreational dive frequency, diver behaviour, and coral damage on reefs near Key Largo, and assessed how pre-dive briefings and other factors affect these damage rates. Recreational divers contacted live stony corals ~ 18 times per scuba dive; most contacts deposited sediment onto corals, but also caused abrasion to coral tissues and fracture of coral skeletons. Divers who received pre-dive ecological briefings caused significantly less coral damage than those who did not, and divers with cameras and/or gloves caused the most damage. The proportion of damaged corals increased significantly with the estimated rate of recreational diving on each reef, and the percent cover of live corals decreased. We conclude that current rates of recreational diving in Key Largo are unsustainable, resulting in damage to >80 % of coral colonies and reduction of live coral cover to <11 % at heavily-dived sites. We recommend that dive tour operators administer pre-dive ecological briefings to all recreational divers, provide extra briefings to camera and glove users, and employ underwater dive guides who intervene when divers inadvertently damage live stony corals. This study provides a scientific basis to support management of intensive ecotourism on Florida coral reefs.