Quantitative estimation of the predation of marine ranched striped jack <Emphasis Type="Italic">Pseudocaranx dentex</Emphasis> by herons

The Goto station of the Japan Sea-Farming Association conducted marine ranching experiments with striped jack Pseudocaranx dentex from 1988 to 1999 in the Goto Islands, Nagasaki, Japan. Marine ranching is a stocking method where released fish are fed for some period after release in order to decrease initial mortality from starvation. Ranched fish were fed for 0, 90, and 15 days after stocking in 1997, 1998, and 1999, respectively. During the experiment, herons (grey heron Ardea cinerea, black-crowned night heron Nycticorax nycticorax, and great egret Egretta alba) were often observed preying on released fish in the ranching area. The present study estimated the number of fish preyed upon by herons during observation periods in 1997, 1998, and 1999 from the number of herons that flew into the ranching area and the predation rate on ranched fish by herons. The former was counted during sightings. The latter was estimated from the sighting observations and heron regurgitations. The number of herons that flew into the ranching area increased with the feeding period. The numbers of fish lost to predation by herons in 1997, 1998, and 1999 were estimated to be 0, 5,741, and 829, respectively.     

Frugivory of carnivores and seed dispersal of fleshy fruits in cool-temperate deciduous forests

Five members of the order Carnivora in the cool-temperate deciduous forests of Japan consume the fruits of trees, and they are potential dispersers of the seeds of fleshy-fruited plants. We studied the frugivory of the Asiatic black bear, Japanese marten, badger, red fox, and raccoon dog in cool-temperate deciduous forest of central Japan. From May 2003 to April 2005, a total of 377 fecal samples of the five carnivores (bears, 91; martens, 158; badgers, 45; foxes, 36; and raccoon dogs, 47) were sampled to determine the presence and frequency of occurrence of seeds. Seeds from 17 plant species, representing about 50% of the fleshy-fruited plants occurring in the study forest, were recovered from the carnivore fecal samples. Large numbers (9–10,256) of seeds were present in those feces. Almost all the seeds of fleshy fruits retrieved from the fecal samples were undamaged whereas no intact acorns or nuts were recovered. These findings suggest that all five carnivores can act as seed dispersers for some fleshy-fruited plants in cool-temperate deciduous forest. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Analysis of juvenile tuna movements as correlated random walk

We explore how a stochastic model provides the most promising avenue towards predicting fish movement. To construct a stochastic model describing fish movement, trajectories of ten juveniles in a water tank were analyzed from a stochastic point of view. The heading angle was defined as a random variable. Our analysis found that the most probable forward heading angle was between 0° and 22.5° (probability ~78%), followed by angles between 22.5° and 45° (probability ~10%). We also found that the choice of future heading angle depends on the current heading angle. Therefore, we treated heading angle state as a first-order Markov process and constructed a correlated random walk model describing juvenile movement in a water tank. Our stochastic model simulated a trajectory similar to observed trajectories. We used the model as a tool for estimating the probability distribution of potential fish path outcomes. We derived the distribution of potential outcomes from a large number of simulations (N = 1000) and investigated these trajectories. We collected a set of juvenile trajectories that collided with the tank and estimated the probability of juvenile collisions with the tank.     

Concentrations of trace elements in <Emphasis Type="Italic">Meretrix</Emphasis> spp. (Mollusca: Bivalva) along the coasts of Vietnam

The dominant coastal bivalve in Vietnam, hard clams Meretrix spp., collected from the South Key Economic Zone (SKEZ), the Mekong River Delta, and the Central Coastal Zone (CCZ) were analyzed for 21 trace elements. Comparison of the results from the three regions indicated that levels of most of the trace elements, especially As, Mo, Sn, and Pb, were highest in the samples collected from the CCZ, whereas most of the trace elements were found to be present at relatively low levels in samples from the SKEZ. The high concentrations of these trace elements in the CCZ, a sparsely populated region with less human activity than the other two regions, were believed to have originated from industrial waste produced in a shipyard. Although the trace element concentrations in the bivalves were within safe levels for human-consumption criteria reported by the United State Food and Drug Administration and the European Commission, estimation of cancer risk based on As concentration indicates that the hard clams from the CCZ pose a high risk to consumers. Thus, the industrial waste produced in the less densely populated region might increase the health risk to consumers via the contamination of bivalves commonly used as food.     

Trace elements in <Emphasis Type="Italic">Anadara</Emphasis> spp. (Mollusca: Bivalva) collected along the coast of Vietnam,with emphasis on regional differences and human health risk assessment

This study measured concentrations of 21 trace elements in whole soft tissue of the blood cockle Anadara spp., which is a common food for local people, collected along the coast of Vietnam. Results showed that concentrations of As, Sr, Mo, Sn, and Pb in cockles collected from Khanh Hoa Province in the Central Coastal Zone (CCZ) had higher values than those from the other regions, while cockles collected from the Mekong River Delta (MRD) showed the highest concentrations of Hg. Regional differences in trace element concentrations of the cockle may be due to differences in human activities, i.e., shipyards in the CCZ and agriculture in the MRD. Trace element concentrations measured in the soft tissues of blood cockles investigated here were within safe levels for human consumption following criteria by the European Commission (EC) and the United States Food and Drug Agency, but several specimens had Cd levels exceeding the EC guidelines of 1 μg/g wet weight. The estimated target hazard quotients for trace elements via consuming bivalves were <1, indicating that the cumulative noncarcinogenic risk was completely insignificant. However, the estimated target cancer risk values by assumed inorganic As concentrations seem to implicate consumption of these cockles as posing potential human health concerns.     

Incorporation of 14CO2 and 15NH4 into amino acids of the two subunits of fraction 1 protein in spinach leaves

In the investigation of nitrogen metabolism in plants, it is important to deal with proteins, which are the end-products of nitrogen metabolism.     

Starvation–refeeding causes cellular stress responses in the gut and liver of Masu salmon Oncorhynchus masou masou

Fisheries Science - Gene expression profiles during the transition from fasting to refeeding were investigated in the gut and liver of Masu salmon Oncorhynchus masou masou. Fish were starved for...