Method for assessing the chronic toxicity of marine and estuarine sediment-associated contaminants using the amphipod Corophium volutator

Acute sediment toxicity tests do not test key life stage events such as moulting and reproduction and therefore do not reveal the longer-term effects of contaminant exposure. A laboratory method is described for determining the chronic toxicity of contaminants associated with whole sediments. The test is conducted using neonates of the estuarine amphipod Corophium volutator at 15 degrees C, salinity 25 psu and a 12 h light:12 h dark photoperiod. The endpoints are survival and growth after 28 days and survival, growth and reproduction of amphipods upon termination of test i.e. reproduction within all control vessels (ca 75 days). The sediment chronic toxicity test was used to investigate the effects of sediments spiked with environmentally relevant preparations of slightly weathered Alaskan North Slope crude oil, including a water-accommodated-fraction (WAF) and a chemically-dispersed (Corexit 9527) WAF. Sediment oil concentrations were quantified using ultra-violet fluorescence. The amphipods exposed to chemically dispersed oil had higher mortality and lower growth rates than control-, Corexit 9527- and WAF-exposed organisms, resulting in reduced reproduction. The described method supplements the standard acute sediment test and would be particularly useful when long-term ecological effects are suspected but acute tests reveal no significant mortality. The sediment chronic test reported herein has shown that sediment that was not evidently toxic during 10-day acute tests could have population-level effects on sediment-dwelling amphipods.     

Dynamic Responses of A Semi-Type Offshore Floating Wind Turbine During Normal State and Emergency Shutdown

This paper addresses joint wind-wave induced dynamic responses of a semi-type offshore floating wind turbine (OFWT) under normal states and fault event conditions. The analysis in this paper is conducted in time domain, using an aero-hydro-servo-elastic simulation code-FAST. Owing to the unique viscous features of the reference system, the original viscous damping model implemented in FAST is replaced with a quadratic one to gain an accurate capture of viscous effects. Simulation cases involve free-decay motion in still water, steady motions in the presence of regular waves and wind as well as dynamic response in operational sea states with and without wind. Simulations also include the cases for transient responses induced by fast blade pitching after emergency shutdown. The features of platform motions, local structural loads and a typical mooring line tension force under a variety of excitations are obtained and investigated.     

Ship propulsion in waves by actively controlled flapping foils

Flapping wings located beneath or to the side of the hull of the ship are investigated as unsteady thrusters, augmenting ship propulsion in waves. The main arrangement consists of horizontal wing(s) in vertical oscillatory motion which is induced by ship heave and pitch, while rotation about the wing pivot axis is actively controlled. In this work we investigate the energy extraction by the system operating in irregular wave conditions and its performance concerning direct conversion to propulsive thrust. More specifically, we consider operation of the flapping foil in waves characterised by a spectrum, corresponding to specific sea state, taking into account the coupling between the hull and the flapping foil dynamics. The effect of the wavy free surface is accounted for through the satisfaction of the corresponding boundary conditions and the consideration of the wave velocity on the formation of the incident flow. Numerical results concerning thrust and power coefficients are presented, indicating that significant thrust can be produced under general operating conditions. The present work can be exploited for the design and optimum control of such systems extracting energy from sea waves for augmenting marine propulsion in rough seas, with simultaneous reduction of ship responses offering also dynamic stabilisation.     

Distributional effects of property rights: Transitions in the Atlantic Herring fishery

A principal challenge in developing any fishery management plan is the allocation of benefits and costs among participants in the fishery. This process is further complicated by imperfect information about future market demand and limited ability to predict the consequences of regulatory change. This paper offers a new approach to policymakers, using econometric analysis to simulate the potential impact of individual tradable quotas (ITQs) in a fishery. We compare the distribution of harvest across participants in the Atlantic Herring fishery under the current open access regime and under a potential ITQ regime, assuming two different levels of future demand. Our results show that production efficiency varies by vessel gear, home-port and relationship with buyers. Some of the predicted consequences of ITQs are: vessels from Massachusetts will gain share relative to those from Maine; trawlers will gain share relative to purse seine vessels; and independent vessels will lose share relative to vessels that are primarily contracted to specific processors or bait companies. These results will help policymakers in developing future management plans for the herring fishery. More generally, this analytical approach can help regulators in any fishery assess the potential impact of alternative policy changes under alternative future demand scenarios.     

Net economic effects of achieving maximum economic yield in fisheries

Improving the economic performance of fisheries is becoming increasingly important in fisheries management, and in some cases, maximum economic yield (MEY) is set as a key management target. However, recent critics of MEY as a management target have argued that a decline in the level of fishing activity necessary to achieve the target will result in a subsequent loss of economic activity elsewhere in the economy and, potentially, a net loss to society. In this paper, an input–output framework is used to estimate the net economic effects of achieving MEY in several Australian fisheries for which there is information on their short- and long-term performances when moving towards MEY. While overall losses were found in the short term, achieving MEY was found to result in a net economic benefit to society in the longer term. Local coastal communities in particular were found to benefit, although some losses were incurred elsewhere in the economy.     

A benthic mucilage event in North-Western Mediterranean Sea and its possible relationships with the summer 2003 European heatwave: short term effects on littoral rocky assemblages

In this contribution we document an anomalous mucilage growth which occurred in June 2003 along the rocky cliffs of the Portofino Promontory (Ligurian Sea, NW Mediterranean Sea), and we describe its dynamics and its negative effects on many benthic taxa. The zooxanthellate scleractinian Cladocora caespitosa underwent ‘bleaching’ and about 40% of biomass of the erect algae was detached by mucilage ‘lianas’ created and strengthened by bottom currents. The 2003 event differed from any other previously occurred in the northern Tyrrhenian Sea, in that the mucilage aggregates were formed by the free‐living form of the Phaeophyceae Acinetospora crinita (Harvey) Kornmann, a not usually dominant species in mucilage aggregates from the north Tyrrhenian Sea. The damage suffered by the benthic organisms living in this area was curtailed by a severe storm, occurred in July, which removed the mucilage to deeper depths, preventing irreversible damages. Only slow growing, perennant organisms, such as corallinales or scleractinians, were seriously affected, but a survey carried out 1 year later, in June 2004, allowed to appreciate a complete recovery of those organisms. This anomalous mucilage event occurred in coincidence of the 2003 European heatwave, and the anomalous temperature increase of seawater has to be regarded as the major contributing event that led to the mucilage outbreak.     

The study on the bottom friction and the breaking coefficient for typhoon waves in radial sand ridges--the Lanshayang Channel as an example

Owing to the interactions among the complex terrain, bottom materials, and the complicate hydrodynam-ics, typhoon waves show special characteristics as big waves appeared at the high water level (HWL) ...     

三门湾多个围垦工程的整体影响数学模型研究

海湾内的围垦工程对潮流及冲淤都将产生影响.以三门湾蛇蟠和下洋涂围垦工程为例,设计了3组试验对比的数值模拟计算方案,对比计算结果表明,预测三门湾内2个围垦工程对水动力环境产生的影响,当讨论单一围垦工程时,应把工程前的海湾状态设置为湾内没有任何其它工程,这样才能得出单个围垦工程对湾内环境的真实影响;当讨论2个围垦工程对水动力环境产生影响时,应进行2个围垦工程整体数学模拟计算,考虑2个围垦工程的叠加累积影响,并与海湾原始状态(即假定海湾在围垦前湾内没有任何其它围垦工程)进行比较,才能得出较为科学的预测结果.     

城市缺水的环境效应及防治措施

水资源短缺是环境恶化的主要原因之一."城市缺水"是当今世界存在的带有普遍性的问题.本文分析了我国城市缺水的类型、缺水所引发的各种环境问题以及所产生的环境效应,并进一步提出了防治措施.结论对城市合理规划、科学管理以及可持续发展战略的实现具有重要的参考价值.