Environmental implications of oil spills from shipping accidents

Levels of hydrocarbons and toxicity of water-soluble fractions of maritime fuels on neotropical invertebrates

Accidents involving fuels and oil spills are among the main sources of hydrocarbons to the marine ecosystems and often damage the biota. Diesel and bunker oil are two examples of fuels with broad application that release hydrocarbons to the aquatic environment and little is known about their toxicity on tropical organisms. This study aimed to assess the toxicity of the water-soluble fraction (WSF) of diesel and bunker oils to neotropical marine invertebrates. Commercial fuels were purchased for WSF extraction, analyzed for total petroleum hydrocarbons (TPH), and polycyclic aromatic hydrocarbons (PAHs), and acute and chronic toxicity determined. The WSF analyzed contained varied levels of TPH and PAHs mixtures, especially low molecular weight PAHs; bunker WSF presented higher amounts of TPH and PAHs. Both WSFs tested produced significant mortality of the brine shrimp Artemia salina, affected the reproduction rate of the copepod Nitokra sp, and impaired the embryo-larval development of the mussel Perna perna and of the sea urchin Lytechinus variegatus. In general WSF from diesel was more toxic to the organisms tested, but bunker WSF was more toxic to embryos of L. variegatus. Toxicity started from concentrations of 3% WSF, which can be environmentally relevant after an oil spill, indicating that marine biota may be adversely affected in short term.

The crucial role of bacterial laccases in the bioremediation of petroleum hydrocarbons

Laccases (EC 1.10.3.2) are a class of metallo-oxidases found in a variety of fungi, plants, and bacteria as well as in certain insects. They can oxidize a wide variety of organic compounds and can be widely applied in many fields, especially in the field of biodegradation and detoxification of environmental pollutants. The practical efficacy of laccases depends on their ability to capture the target substance as well as their catalytic activity, which is related to their catalytic center, substrate selectivity, and substrate tolerance. Over the past few decades, many laccases have been identified in plants and fungi. Concurrently, bacterial laccases have received increasing attention because of their high thermostability and high tolerance to organic compounds. The aim of this review is to summarize the role of bacterial laccases in the bioremediation of petroleum hydrocarbons and to outline the correlation between the molecular structure of the mononuclear T1 Cu center of bacterial laccases and their substrate preference.

A standardised approach to the environmental risk assessment of potentially polluting wrecks

The potential risk to the marine environment of oil release from potentially polluting wrecks (PPW) is increasingly being acknowledged, and in some instances remediation actions have been required. However, where a PPW has been identified, there remains a great deal of uncertainty around the environmental risk it may pose. Estimating the likelihood of a wreck to release oil and the threat to marine receptors remains a challenge. In addition, removing oil from wrecks is not always cost effective, so a proactive approach is recommended to identify PPW that pose the greatest risk to sensitive marine ecosystems and local economies and communities. This paper presents a desk-based assessment approach which addresses PPW, and the risk they pose to environmental and socio-economic marine receptors, using modelled scenarios and a framework and scoring system. This approach can be used to inform proactive management options for PPW and can be applied worldwide.

Use of metal-enhanced fluorescence spectroscopy for detection of polycyclic aromatic hydrocarbons in diesel oil emulsions in artificial seawater

In this study, we employed the metal-enhanced fluorescence (MEF) method for the detection of polycyclic aromatic hydrocarbons (PAHs) in diesel oil emulsions in artificial seawater. Silver nanoparticles with an average diameter of 80 nm were immobilized onto silanized quartz as MEF substrates. Excited by illumination at 355 nm, a 4.6-fold increase in the fluorescence signals of PAHs was recorded when MEF substrates were used. The finite-difference time-domain (FDTD) method was used to provide mechanistic insights into the fluorescence enhancement. Monitoring water pollution has environmental significance and MEF spectroscopy is finding direct applications in this field.

Interspecific hybridization increased in congeneric flatfishes after the Prestige oil spill

Marine species with relatively low migratory capacity are threatened by habitat alterations derived from human activities. In November 2002 the tanker Prestige sank off the Spanish northwest coast releasing 70,000 tons of fuel and damaging biota in the area. Despite efforts to clean the damaged areas, fuel remnants have affected marine species over the last nine years. This study is focused on two flatfish, Lepidorhombus boscii (four-spotted megrim) and L. whiffiagonis (megrim), whose spawning areas are located at the edge of the continental platform. We have analyzed megrim samples from North Spanish and French waters obtained before and after the oil spill. Genotypes at the nuclear marker 5S rDNA indicate a significant increase in interspecific hybridization after the Prestige accident, likely due to forced spawning overlap. The mitochondrial D-Loop region was employed for determining the direction of hybrid crosses, which were most frequently L. boscii female x L. whiffiagonis male. Reduced ability of L. boscii females to select conspecific mates would explain such asymmetric hybridization. To our knowledge this is the first time that increased hybridization between fish species can be associated to an oil spill. These results illustrate the potential long-term effect of petrol wastes on wild fish species.