Australian Institute of Marine Science, Townsville, Australia
Received date: April 24, 2012; Accepted date: April 25, 2012; Published date: April 27, 2012
Citation: Motti C (2012) Environmental Marine Metabolomics: From Whole Organism System Biology to Ecosystem Management. J Marine Sci Res Dev 2:e110. doi: 10.4172/2155-9910.1000e110
Copyright: © 2012 Motti C. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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In recent times marine ecosystems have come under immense pressure from a variety of environmental and anthropogenic stresses. The number of reports detailing the decline in biodiversity and the increase in prevalence of disease and mortality within marine ecosystems globally has spiked in the last decade [1-7]. Environmental managers and governments are demanding detailed information on the potential of environmental change, and more specifically climate change, to disturb population dynamics, community structure and ecosystem processes. Accurate prognoses and implementable strategies are also required to deal with, halt and even reverse such detrimental outcomes. These issues not only affect the health of the planet but also have significant downstream impacts on global commercial enterprises including tourism, mining and fisheries (both commercial and recreational) .
Sessile invertebrates are key structural and functional components of many varied and complex marine ecosystems. As a result they have developed unique metabolic and physiological capabilities to survive in these challenging environments making them useful as so called “sentinel species”, especially in the study of coral reefs . Information so far suggests that climate change and anthropogenic stressors are impacting on coral reefs globally . In addition, complex interactions such as symbiosis and benthic-pelagic coupling across a wide range of marine habitats are not well understood for many organisms. The current understanding of these processes and the baseline data for many marine organisms is insufficient for advancing environmental research, hence the identification of suitable and reliable biomarkers which can act as early bioindicators of change in these marine ecosystems is non-trivial.
Metabolomics is the systematic study of the global metabolite profile of a living biological system (cell, tissue, or organism). It seeks not only to identify but also understand the concentrations and fluxes of endogenous metabolites under a given set of standard conditions and perturbations [10,11]. These metabolites are generally the product of gene expression resulting from the interaction of the genome with its environment, and range from metabolic intermediates, hormones and signaling molecules to structurally, highly diverse, secondary metabolites whose ecological roles are not yet fully understood. Detailed descriptions of these metabolic pathways will facilitate further understanding of the biosynthesis and metabolism of these metabolites thus directing the search for potential biomarkers for the health and quality of the marine ecosystem.
Metabolomics has been widely applied in medicine to accurately diagnosis the early stages of disease leading to the implementation of optimised treatments, including monitoring the response of patients to these treatments, and improved prognoses . This has culminated in the collation of the human metabolome, consisting of approximately 2500 metabolites, 1200 drugs and 3500 food components . Likewise, over 50,000 metabolites have been characterized from the plant kingdom . More recently metabolomics has been used as a tool to assess and better understand the impacts of environmental stressors on sentinel species of marine organisms including plants, microbes, invertebrates and vertebrates [11,15,16]. Environmental stressors include: physical factors (biogeography , temporal and spatial boundaries, elevated temperature, water quality and nutrient enrichment), biological factors (complex life stage changes, symbiosis , circadian rhythms, predation, competition, alien species and disease development ) and chemical factors (ocean acidification , urban and industrial pollution  and dissolved organic matter ). Metabolomics also provides a unique opportunity to assess the effects of multistressor exposures and decouple these processes to define initial metabolic signatures and ultimately identify bioindicators for the health of the environment.
Three methodologies are routinely used in metabolomics studies: targeted metabolomics (quantitative analysis of a known metabolite), non-targeted metabolite profiling (semi-quantitative analysis of a metabolite set), and non-targeted metabolic fingerprinting (qualitative analysis of the total metabolite profile) . Such investigations rely on a multidisciplinary approach requiring expertise on the biology of a wide variety of marine organisms (ranging from microbes to plants and invertebrates to vertebrates) coupled with a variety of analytical technologies including, but not limited to, high-field Nuclear Magnetic Resonance (NMR) [22,23], Chemical Shift Imaging (CSI)  infrared (FTIR) , and mass spectrometry (with a variety of ionisation techniques in combination with either direct injection or chromatographic methods, i.e. GC-MS , LC-MS , LC-FTMS , CE-MS , or LC-MS-NMR ). These analytical methods are complemented by a range of bioinformatic tools (R, AMIX, Chenomx, AMDIS) and existing chemical databases (Metlin, BMRB, MMCD, MassBank, HMDB) along with more recently developed integrated workflow tools (SimCell), to name but a few [30,31]. Currently the measurement of a complete metabolite pool of an organism is impossible to achieve with a single analytical method.
Although a logical extension of natural products chemistry and marine chemical ecology, marine environmental metabolomics has emerged as a discipline in its own right over the past two decades . The major hurdle faced by researchers today is that it is still in its infancy and as such the databases available are limited. Moreover, not all metabolomics studies, by virtue of the detection methods available and the complexity of the chemistry in the sample which influences sample preparation (i.e. volatile vs non-volatile, polar vs non-polar), are quantitative. Comprehensive investigation of the marine metabolome is further impeded by its enormous complexity and dynamics, and as such there is great risk associated with relying solely on these data to address the impact of stressors on organisms and ecosystems.
Through the advancement of metabolomic techniques, greater knowledge of sentinel marine organisms can influence and contribute to: 1) a more comprehensive understanding of their system biology and the differences between them, 2) the impacts anthropogenic or environmental factors have on them, and 3) their ability to recover from such perturbations. These data will drive development and implementation of new approaches in environmental impact assessments, environmental modelling and ecosystem-scale bio measurement strategies. In addition, metabolomics is the endpoint of the “omics cascade”, therefore closest to the phenotype and best placed to determine how the changes in the metabolite profile correlate to the physiological status of the whole organism . Even so, its full potential will only be realised using a truly integrated approach with proteomics, transcriptomics, and genomics epigenomics . Furthermore, there are few laboratories equipped to undertake all aspects of this research and as such it is important to foster strong multidisciplinary collaborations if the scientific community, management agencies and policy makers are to response positively to the issues facing the marine environment today and into the future.
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