A Model Study of the Circulation in the Pearl River Estuary (PRE) and Its Adjacent Coastal Waters: 1. Simulations and Comparison with Observations

The Princeton Ocean Model is used to study the circulation features in the Pearl River Estuary and their responses to tide, river discharge, wind, and heat flux in the winter dry and summer wet seasons. The model has an orthogonal curvilinear grid in the horizontal plane with variable spacing from 0.5 km in the estuary to 1 km on the shelf and 15 sigma levels in the vertical direction. The initial conditions and the subtidal open boundary forcing are obtained from an associated larger-scale model of the northern South China Sea. Buoyancy forcing uses the climatological monthly heat fluxes and river discharges, and both the climatological monthly wind and the realistic wind are used in the sensitivity experiments. The tidal forcing is represented by sinusoidal functions with the observed amplitudes and phases. In this paper, the simulated tide is first examined. The simulated seasonal distributions of the salinity, as well as the temporal variations of the salinity and velocity over a tidal cycle are described and then compared with the in situ survey data from July 1999 and January 2000. The model successfully reproduces the main hydrodynamic processes, such as the stratification, mixing, frontal dynamics, summer upwelling, two-layer gravitational circulation, etc., and the distributions of hydrodynamic parameters in the Pearl River Estuary and coastal waters for both the winter and the summer season.

Voluntary Participation in Regional Fisheries Management Council Meetings

Insufficient and unrepresentative participation in voluntary public hearings and policy discussions has been problematic since Aristotle's time. In fisheries, research has shown that involvement is dominated by financially resourceful and extreme-opinion stakeholders and tends to advantage groups that have a lower cost of attendance. Stakeholders may exhibit only one or all of these traits but can be still similarly advantaged. The opposites of these traits tend to characterize the disadvantaged, such as the middle-ground opinions, the less wealthy or organized, and the more remote stakeholders. Remoteness or distance is the most straightforward and objective of these characteristics to measure. We analyzed the New England Fishery Management Council's sign-in sheets for 2003-2006, estimating participants' travel distance and associations with the groundfish, scallop, and herring industries. We also evaluated the representativeness of participation by comparing attendance to landings and permit distributions. The distance analysis showed a significant correlation between attendance levels and costs via travel distance. These results suggest a potential bias toward those stakeholders residing closer to meeting locations, possibly disadvantaging parties who are further and must incur higher costs. However, few significant differences were found between the actual fishing industry and attendee distributions, suggesting that the geographical distribution of the meeting attendees is statistically similar to that of the larger fishery. The interpretation of these results must take into consideration the limited time span of the analysis, as policy changes may have altered the industry make-up and location prior to our study. Furthermore, the limited geographical input of stakeholders may lend bias to the Council's perception of ecological and social conditions throughout the spatial range of the fishery. These factors should be further considered in the policy-formation process in order to incorporate a broader range of stakeholder input.

Distributions and Variability of Particulate Organic Matter in a Coastal Upwelling System

In this study we examined the spatial and temporal variability of particulate organic material (POM) off Oregon during the upwelling season. High-resolution vertical profiling of beam attenuation was conducted along two cross-shelf transects. One transect was located in a region where the shelf is relatively uniform and narrow (off Cascade Head (CH)); the second transect was located in a region where the shelf is shallow and wide (off Cape Perpetua (CP)). In addition, water samples were collected for direct analysis of chlorophyll, particulate organic carbon (POC), and particulate organic nitrogen (PON). Beam attenuation was highly correlated with POC and PON. Striking differences in distribution patterns and characteristics of POM were observed between CH and CP. Off CH, elevated concentrations of chlorophyll and POC were restricted to the inner shelf and were highly variable in time. The magnitude of the observed short-term temporal variability was of the same order as that of the seasonal variability reported in previous studies. Elevated concentrations of nondegraded chlorophyll and POM were observed near the bottom. Downwelling and rapid sinking are two mechanisms by which phytoplankton cells can be delivered to the bottom before being degraded. POM may be then transported across the shelf via the benthic nepheloid layer. Along the CP transect, concentrations of POM were generally higher than they were along the CH transect and extended farther across the shelf. Characteristics of surface POM, namely, C: N ratios and carbon: chlorophyll ratios, differed between the two sites. These differences can be attributed to differences in shelf circulation.