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In this paper, we tested the hydrodynamic characteristics of a new, double-winged otter board that consists of a forewing, a leading edge slat and a trailing edge flap. Flume experiments were conducted in a circulating flume tank by using a model with an aspect ratio (AR) of 0.85 and a horizontal planform area (S) of 0.09 m2. The results indicated that the critical angle (αcr) of the model was 44°, whereas the maximum lift coefficient (CLmax) was up to 1.715, and the door efficiency (K) was 1.122. The attack angle (α) ranged from 30° to 48° and from 10° to 46° when the lift coefficient (CL) and door efficiency (K) were greater than 1.2 and 1.0, respectively. To compare the difference between double-winged otter board and traditional Morgere Polyvalent Ovale, same model of Morgere Polyvalent Ovale was also tested under the same experimental conditions. The critical angle (αcr) and maximum of lift coefficient (CLmax) of the doublewinged otter board were 37.5% and 14.6% larger than those of the Morgere Polyvalent Ovale. Therefore, we concluded that the novel, double-winged otter board was more suitable for bottom trawling fisheries in the deep water of the Mauretania Sea due to its better hydrodynamic characteristics and stability.

Catch per unit of effort (CPUE) data can display spatial autocorrelation. However, most of the CPUE standardization methods developed so far assumes independency of observations for the dependent variable, which is often invalid. In this study, we collected data of two fisheries, squid jigging fishery and mackerel trawl fishery. We used standard generalized linear model (GLM) and spatial GLMs to compare the impact of spatial autocorrelation on CPUE standardization for different fisheries. We found that spatial-GLMs perform better than standard-GLM for both fisheries. The overestimation of precision of CPUE estimates was observed in both fisheries. Moran’s I was used to quantify the level of autocorrelation for the two fisheries. The results show that autocorrelation in mackerel trawl fishery was much stronger than that in squid jigging fishery. According to the results of this paper, we highly recommend to account for spatial autocorrelation when using GLM to standardize CPUE data derived from commercial fisheries.

It is difficult to determine the photosynthetic parameters of non-flat leaves/green stems using photosynthetic instruments, due to the unusual morphology of both organs, especially for Suaeda salsaand Salicornia bigeloviias two seawater-tolerant vegetables. To solve the problem, we developed a simple, practical, and effective method to measure and calculate the photosynthetic parameters (such as PN, gs, E) based on unit fresh mass, instead of leaf area. The light/CO2/temperature response curves of the plants can also be measured by this method. This new method is more effective, stable, and reliable than conventional methods for plants with non-flat leaves. In addition, the relative notes on measurements and calculation of photosynthetic parameters were discussed in this paper. This method solves technical difficulties in photosynthetic parameter determination of the two seawater-tolerant vegetables and similar plants.

This paper investigates the response of the thermocline depth (TD) in the South China Sea (SCS) to the El Niño-Southern Oscillation (ENSO) events using 51-year (from 1960 to 2010) monthly seawater temperature and surface wind stress data acquired from the Simple Ocean Data Assimilation (SODA), together with heat flux data from the National Centers for Environmental Prediction (NCEP), precipitation data from the National Oceanic and Atmospheric Administration (NOAA) and evaporation data from the Woods Hole Oceanographic Institution (WHOI). It is indicated that the response of the SCS TD to the El Niño or La Niña events is in opposite phase. On one hand, the spatial-averaged TDs in the SCS (deeper than 200 m) appear as negative and positive anomalies during the mature phase of the El Niño and La Niña events, respectively. On the other hand, from June of the El Niño year to the subsequent April, the spatial patterns of TD in the north and south of 12°N appear as negative and positive anomalies, respectively, but present positive and negative anomalies for the La Niña case. However, positive and negative TD anomalies occur almost in the entire SCS in May of the subsequent year of the El Niño and La Niña events, respectively. It is suggested that the response of the TD in the SCS to the ENSO events is mainly caused by the sea surface buoyancy flux and the wind stress curl.

The genus Muelleriais reported for the first time from China in this paper. The new diatom species Muelleria pseudogibbulasp. nov. was observed during a survey of diatoms from Zoigê Wetland, Sichuan Province, China. The morphological characters of this new species were documented by light and scanning electron microscope and compared with similar species. M. pseudogibbulais characterized by its lanceolate to linear-lanceolate valve outline with rounded apices, two longitudinal canals running parallel to each side of the raphe, proximal ends of the raphe deflected to the same directions and finishing before the first row of areolae, and curved distal raphe ends, forming two divergent branches.

Abstract: Using the most recent hydrologic and water quality data issued by U.S. Geological Survey, this paper deals with the pollution of the lower Mississippi River for the 1978–1981 water years and compares the water pollution of this period with that of the 1973–1977 water years. The water quality of the lower Mississippi River has not been evaluated comprehensively. This paper utilizes the Cartesian coordinates approach in an appraisal of water quality of the Mississippi River for the first time. Thus, it provides a foundation for the further comprehensive evaluation of environmental quality and research of water resources.