Evaluation of pollution effects in marine organisms: "Old" and "new generation" biomarkers

Marine pollution has become of global concern in recent years. In fact marine environments and their related ecosystem services (climate regulation, primary production, molecular oxygen formation, food provisioning, recreational experiences) are threatened by many human activities around the world and are affected by either point or nonpoint source pollution. Numerous chemicals can be present simultaneously in the aquatic environment and chemical interactions in a mixture can cause complex and substantial changes in the pure chemical properties of its constituents, including bioavailability and toxicity. For this reason, there is a growing awareness that focusing mainly on chemical data of pollutant concentration in environmental matrices is insufficient to reliably assess the potential risks for the environmental and human health. The growing attention to these concerns has promoted the development of environmental "diagnostic" tools to allow early warning detection of pollution exposure. The need to detect the biological effects of chemical contaminants also at low concentration and in complex mixture has increased the study of the relationships between exposure to chemical contaminants and alterations in several biochemical and cellular processes in the organisms in order to use the latter as markers (commonly referred to as biomarkers) of exposure and early response to chemical contaminants. Today, biomarkers are an essential component of environmental monitoring programs in marine environments in several countries in support of the commonly used chemical monitoring. Biomarker measurements in bioindicator organisms promise to become valuable tools for environmental monitoring aimed to surveillance, hazard assessment, or to document remediation in marine environments. In this chapter we report and analyze insights and perspectives in the biomarker approach, including the detection of the impact of biological pollution in marine environment. In sections I and II we will introduce the "biomarkers world" in particular, in section II the biological basis of biomarkers as part of detoxification mechanism of environmental pollution on living organism will be analyzed. In section III we will deal with the bioindicator organisms utilized in the biomarkers approach. Definition, classification and utility of biomarkers will be discussed in section IV. In sections V and VI we will review "old" biomarkers, such as metallothionein and acetylcholinesterase. Other important protein biomarkers (biotransformation enzymes, stress proteins, vitellogenin, multi drug resistance proteins) will be treated in section VII, dwelling especially on multi drug resistance proteins, which can be defined as "new generation" type biomarkers. In sections VIII and IX another important class of biomarkers will be treated, such as antioxidant enzymes, and the immunological response. Another important aspect is discussed in section X: e.g. the biomarkers of genotoxicity. In section XI, behavioural biomarkers will be considered. Section XII will deal with the new generation of high throughput molecular biomarkers often referred as to "omics". This part includes transcriptomics, proteomics and metabolomics. Finally, the use of biomarkers in marine biomonitoring programs and risk assessment procedures will be discussed in section XIII.