Future marine biodiversity and ecosystem functioning research issues
The European Network of Excellence on Marine Biodiversity and Ecosystem Functioning (MarBEF) has, over the past five years of its existence, moulded a scientific community that has never been so conceptually and operationally united and productive. However, marine science is still developing and we still understand the ocean less than the terrestrial environment. For us, the oceans are foreign habitats which we may enter but not yet inhabit.
MarBEF scientists have focused on and identified many critical marine biodiversity issues, which are now much clearer than before, but MarBEF has also revealed areas of weakness that require concentrated effort. These are the following:
Impacts of global climate change
Although there is now strong evidence for changes in the global climate, the medium term and long-term effects on the marine environment are still open to debate. Marine systems, from polar ice to coral reefs are charismatic systems which are highly vulnerable to temperature, sea-level and storm frequency changes.
Evidence of migrational responses to climate are accumulating and act as an early warning of the nature of community alteration in the face of global change scenarios. Studies of modifications to ecosystem variation and functionality resulting from climate change must remain of the highest priority over the coming ten years. Some of these studies require long-term databases that are now recognised as being highly valuable and important to maintain.
Many current topics in marine biodiversity research are taking place on very large spatial scales and over long-term periods. They are among other things creating baseline assessments in the marine realm, for assessing impacts of climate change on marine biodiversity, and studying the mechanisms by which alien species are introduced.
Therefore, MarBEF recognised that its scientists require analyses on a global scale and funded the LargeNet project. LargeNet collected and integrated a large amount of data, comprising pelagic, rocky shore and soft-bottom benthos data from across Europe. This data established a baseline for current biodiversity analyses and future investigations within a changing world. This scale of data collection is necessary to be able to understand and anticipate the consequences of environmental variations on biodiversity. The database has, for example, been employed to assess the current biodiversity status and future changes in marine communities. See also here.
Synergy of anthropogenic impacts additional to global warming
The oceans have been used as a means of transport, resource acquisition and disposal for centuries. While attitudes to the exploitation of the seas are changing, there is still a requirement to understand and manage the transport pathways and the effects of pollutants arising from ocean exploitation. These pathways include run-off of contaminants from the land, direct input through energy (thermal pollution), liquid and solid waste from vessels and accidental addition of xenobiotic material.
Research has often focused on a single stress factor, but multi-stress systems and modelling are also required. This area of work has particular implications given the overlap between stresses resulting from environmental change. Marine exploitation carries with it a number of responsibilities toward environmental management. Biodiversity impacts include those caused by introduced invasive species and consequent biodiversity and functionality effects.
In addition, fisheries practice (e.g., benthic trawling) has the capacity to cause major localised and regional impact of the shelf ocean systems. In terms of non-fisheries impacts, study of the diverse impacts (noise, habitat disturbance, resource removal) caused by commercial companies (gravel extraction, dredging, oil industry) must continue to be a central issue in protecting oceanic systems. Research to characterise ecosystem- and region-specific impacts of multiple stressors is essential for the effective implementation of the new Marine Strategy Framework Directive.
Coastal management can only be performed if its based on sound knowledge and international cooperation. The passage from knowledge generation to knowledge-based management should not stop our quest for new knowledge, the two should in fact stimulate each other. The speed at which new knowledge can be translated into management practice needs to be improved. The calls for future research development must be aimed at filling gaps in our knowledge – gaps that must be identified by the scientific community, the developers of policy and the stakeholders.
Phase shifts: alternate stable states
Theoretically, a single ecosystem may exist in a number of possible states, or ‘alternate stable states.’ These alternatives are often considered to represent “good” or “poor” conditions – for example, the switch from a diverse pelagic food web (good) to a low-diversity system dominated by jellyfish (poor). The various alternate stable states for each system must be recognised, triggers causing shifts between them must be characterised, and impacts of shifts assessed.
Habitat diversity is of paramount importance in sustaining biodiversity. This is recognised by the EC Habitats Directive, but marine habitats are poorly represented by this directive. European marine habitats must be classified under a consistent rationale and then mapped, as has already been done for terrestrial habitats.
Although the link between biodiversity and ecosystem functioning is now well established, its nature varies in different environmental contexts. Widely replicated experiments are necessary to be more able to predict future changes in ecosystem functioning.
The application of the Ecosystem Approach calls for proper understanding of ecosystem functioning for the management of fisheries, coastal zones, shelf seas, deep seas and Marine Protected Areas. Many marine stations specialise in the study of coastal marine biodiversity and ecosystem functioning, and oceanographic vessels are needed to study offshore marine biodiversity and ecosystem functioning.
The number of species must be linked to habitat diversity. Regional and world monographs on each species group should be prepared, based on sound taxonomic revisions, to cope with the fast-changing species diversity of European seas. We are not ready to quantify and evaluate the impact of global change on our marine biota (with some exceptions, e.g., the Atlas of Exotic Species published by CIESM) until we have accumulated sufficient baseline data. The number of species found in a given habitat throughout Europe is changing rapidly. Cold-water species are under stress, whereas warm-water species are thriving and expanding their distributions, with the arrival of many non-indigenous species (NIS) of tropical affinity. The impact of these changes on ecosystem functioning should be assessed, even though it is not clear if the dramatic changes we are going through are due to global warming or to other human activities.
The role of species
Despite our relatively advanced knowledge in some areas, the role or capabilities of many species are still unknown: this is a serious gap in our understanding of marine systems. Indeed, the majority of species are probably unknown, and this is another gap. The life cycles of most of the species we can identify are still unknown. Fundamental research on the natural history of marine systems and their inhabitants must continue.
Biodiversity at the genetic level
Today, ecological information is available for most keystone species of marine environments, but we lack information on the genetic variability of even the most important species. There is still a requirement to resolve the genetic structure of species at the level of detail necessary to make predictions of how global and local perturbations will influence the structuring and the phylogeography of species and their populations. This knowledge is of tremendous importance for interpreting the different reactions of neighbouring individuals or colonies, living in the same environment, to perturbations.
In addition, most benthic organisms disperse mostly in the larval phase, as the adult phase is sessile or of low motility. So the only way to assess the dispersal efficiency is through the evaluation of genetic flux. Analysis of the factors which influence the genetic structure of populations of marine taxa will explain the establishment and the evolution of patterns of biodiversity at different scales (population and species structuring), from local to European level. This will make it possible to draw sensitivity maps and to help design the boundaries of Marine Protected Areas.
Too little is currently known about the diversity of bacteria, archae, viruses and small protists in European waters. This is mainly because the technologies, used to estimate the number of species, provide widely different values and have trouble detecting, quantifying and identifying rare organisms. Also, studies have been performed in very localised sites. The study areas must be expanded using new technology.
Viruses are the most abundant and genetically diverse organisms in the marine environment. It is clear that viruses cause a significant amount of mortality on populations of important marine organisms (such as plankton organisms). This has a significant impact on the global biological carbon pump (and thus the CO2 flux towards the ocean). In addition to this role in global geochemical cycles, marine viruses also include pathogens of higher organisms, including viruses with poorly understood impacts on aquaculture.
The enormous variety of marine viruses may also represent a source of potential human diseases. Some marine caliciviruses, for example, are thought to cause disease in humans, but little is known about the potential of marine viruses to infect terrestrial organisms. An important priority for future research will be to obtain a more complete picture of the genetic diversity inherent in populations of marine viruses. These studies should be coupled with functional analyses that will enable a better understanding of their impact on ecosystems and, indirectly, on geochemical cycles.
In many research areas , modelling is very effective, particularly in slowly developing and predictable systems. However, in a period of rapid change such as we are experiencing, irregularities are extremely important. We must develop models that cope with irregular events, identify trends and predict scenarios. It should be emphasised, however, that data and understanding derived from experiments are essential to underpin models, particularly for regionally focused models.
- Heip, C., Hummel, H., van Avesaath, P., Appeltans, W., Arvanitidis, C., Aspden, R., Austen, M., Boero, F., Bouma, TJ., Boxshall, G., Buchholz, F., Crowe, T., Delaney, A., Deprez, T., Emblow, C., Feral, JP., Gasol, JM., Gooday, A., Harder, J., Ianora, A., Kraberg, A., Mackenzie, B., Ojaveer, H., Paterson, D., Rumohr, H., Schiedek, D., Sokolowski, A., Somerfield, P., Sousa Pinto, I., Vincx, M., Węsławski, JM., Nash, R. (2009). Marine Biodiversity and Ecosystem Functioning. Printbase, Dublin, Ireland ISSN 2009-2539