Modelling the effects of physical–biological interactions and spatial variability in spawning and nursery areas on transport and retention of sardine Sardinops sagax eggs and larvae in the southern Benguela ecosystem

A particle-tracking individual-based model (IBM) coupled with a 3-D hydrodynamic model was used to investigate how spatial variability in spawning and nursery grounds may influence transport and retention of sardine (Sardinops sagax) eggs and larvae in the southern Benguela ecosystem. A temperature-dependent Bělehrádek development model based on laboratory growth data was used to determine the duration of one egg and two larval stages. Successful transport/retention depended on each particle's stage of development rather than its age. Results show that recruitment could occur in two distinct nursery areas on the west and south coasts of South Africa. Three viable recruitment ‘systems’ were identified: two are retention-based (spawned and retained on the west coast (WC–WC) or the south coast (SC–SC)) and one is transport-based (spawned on the south coast and transported to the west coast (SC–WC)). In the WC–WC system, the vertical distribution of eggs influenced retention; at intermediate depths of spawning (25–50 m) eggs avoided both offshore Ekman drift and deep cold water. In the SC–SC system, the area of spawning was important; > 50% of eggs from the eastern Agulhas Bank (EAB) were retained in the south coast nursery grounds, whereas very few eggs were transported there from west of Cape Agulhas. In the SC–WC system, area of spawning was also important; 40% of the eggs spawned on the western Agulhas Bank (WAB) were transported to the west coast nursery ground. Sardine life history strategy could be divided between two main systems: the west coast system (spawning on the WAB and WC, and recruiting to the WC) and the Agulhas Bank system (spawning on the central and eastern Agulhas Bank, and recruiting to the SC).     

储油罐计算机监控系统设计与实现

将分布式监控系统引入到机务段油库油罐监控系统,通过分布式系统管理和控制喷淋降温、火警灭火、液位监测、输油等子系统的方法,实现了油库油罐监控的自动控制和数据管理。     

Selection of techniques for reducing shipping NOx and SOx emissions

This paper develops a subjective generic methodology for providing ship owners with a transparent evaluation tool for selecting their preferred NOx and SOx control techniques. We quantitatively analyse the merits of the control methods available in marine air pollution control practice using data collected from shipping companies, shipyards and maritime academies. We also prioritize the applicable control techniques with respect to operational shipping environments.     

Distribution and diet of larval and juvenile Arctic cod (Boreogadus saida) in the shallow Canadian Beaufort Sea

The distribution and diet of larval and juvenile Arctic cod (Boreogadus saida) were studied during summer 2005 in the coastal Canadian Beaufort Sea. A total of 275 individuals were captured and the highest abundance was observed at station depths of 20–30 m. This corresponds well with the location of the frontal zone where the Mackenzie River plume water and open sea water meet. Diet examinations were performed on 220 Arctic cod, which were found undamaged from sampling. We observed a gradual decrease in prey number per fish and increase in prey size as larvae grew which corresponded to a shift from Rotifera and nauplii towards larger copepodid stages. However, at all sizes, the larvae remain generalists and feed on a broad range of organisms. Environmental changes due to climate warming could have a two-fold impact on fish larvae feeding in the studied region. First, the potential for increased primary production may lead to increased zooplankton production that may impact the feeding and nutrition positively. On the other hand, greater discharge of turbid water from the Mackenzie River may reduce light penetration in the water column that may negatively influence the ability of visual predators to successively forage.     

The delimitation of exclusive economic zones

In this paper Admiral Kapoor examines some of the problems relating to the delimitation of maritime boundaries, particularly that of exclusive economic zones, as they affect the hydrographic surveyor.     

Airport system planning—a U.K. study

There is growing public pressure, from environmentalist groups and others, for the imposition of lorry bans in urban areas. In the U.K. such bans have so far only been imposed as through‐route bans by small towns, such as Windsor, where the overall impact on operators and on road freight costs is limited. The Greater London Council's response to the pressure for lorry bans has been to set up a Committee of Inquiry to examine the impact of an access ban on the heaviest lorries in the London area. The proposed ban would apply to an area enclosed by the M25 orbital motorway within which vehicles above a specified gross tonnage would not be allowed to operate. A number of metropolitan authorities elsewhere in the U.K. are thought to be considering similar restrictions on lorries.

In this paper, the impact of area lorry bans on goods vehicle operating costs is discussed. It is suggested that practices based on “direct distribution” techniques may prove less costly than the operating alternatives that have been evaluated in the past which include public transhipment depots and the exclusive use of small vehicles.     

Positive impact of distribution centres on the environment

The transport sector in general, and trucks in particular, generates a significant amount of emissions in Australia. It appears the trend will escalate unless different measures are taken to reduce the reliance of freight transport on trucks. This paper discusses the benefits of distribution centres as a means to reduce road congestion, increase safety, protect the environment by reducing atmospheric pollution and improve freight distribution. It also provides the effective use of the existing rail network and its infrastructure and improves the lead-time as well as lowering the cost of transportation of cargo. It also investigates the positive impact of distribution centres located near to manufacturing and farming production units. A simulation model has been developed and used to help determine the amount of atmospheric pollution produced by two modes of land transport, rail and road, for the movement of containers between port and destination. Results derived from the model provide evidence about a preferred land-transport regime. The paper has two sections: (1) the role of distribution centres in the chain of transport and (2) the impact of distribution centres on the environment. The first section investigates the feasibility of the implementation of distribution centres in the State of Victoria with respect to rail line capacity and location allocation. The second section presents an additional simulation model that investigates the role of a distribution centre in relation to the amount of atmospheric pollution produced by rail and road, while containers are carried between port and destination.     

An economic assessment of the impacts of the MOSE barriers on Venice port activities

To protect Venice from flooding, a number of protective measures have been adopted, including a system of mobile barriers known as MOSE. These separate the lagoon from the surges in the Adriatic Sea but interfere with shipping and on port activities. We estimate direct costs on ship traffic resulting from the use of MOSE, i.e., the additional costs of longer waiting time when passing through the Venice Lagoon. Our estimate uses inputs from a hydrodynamic model applied to the ship traffic between 2000 and 2002 and indicate that these costs range from €347,943 to €1.3 million a year, depending on the hypotheses adopted.     

A transit ridership‐revenue model

The paper outlines the theoretical underpinnings of an urban mass transit revenue and ridership model designed to provide medium term forecasts of future trends in situations of data sparsity. The specific example laid out in the paper relates to the Greater Vancouver Regional District but the framework is of general applicability. Much of the informational input at the initial stage is of a general kind and details of the specific transit system and local area are of the sort which should be readily available to most urban authorities. The model developed is designed for use on a desk‐top micro‐computer and offers an inter‐active method of forecasting. The operator has the facility to both consider fare policy sensitivity and review alternative scenarios about future trends in exogenous factors. A selection of forecasts developed for the GVRD is provided to reveal the main features of the approach.     

Energy efficiency,technological change and the dieselization of agriculture in the United States

This study focuses on the increase in the relative importance of diesel fuel consumption on farms in the United States over the 1971–1989 period. Four factors are identified as being central to the observed trend. These include the relative efficiency of diesel powered equipment versus gasoline powered equipment, technological changes that have impacted energy efficiency, the trend towards larger farms, and the enhanced energy conservation by farmers as a result of the adoption of reduced tillage practices.