Introduction to MarBEF research

Marine biodiversity

The primary topic which is investigated by MarBEF scientists is marine biodiversity. All three domains of live, bacteria, archaea and eukarya and are present in the marine environment and almost 230.000 marine species have been scientifically described. However this only represents a fraction of the number of species existing in most groups. Difficultly accessible environments, such as the deep-sea floor, chemosynthetic environments or marine caves are explored new species are continuously being discovered. These newly discovered species may belong to previously unknown higher taxa, in some cases even previously unknown phyla. The availability of rapid sequencing technologies has shown that variability in the microbial domain, including the small eukaryotes, is extremely high and that tens of thousands of ‘species’ may occur in a single litre of sea water. The estimates of the number of marine species that remain to be described are therefore very uncertain.

Ecosystem functioning

Many species of coastal plankton are active for a short time and remain in the sediments as resting stages, sometimes for very long periods.

Different from terrestrial systems

Compared to terrestrial ecology, surprisingly little theoretical foundations or experiments have been developed to investigate marine biodiversity. Considering the extensive knowledge on terrestrial ecosystems, one basic question is whether marine and terrestrial ecosystems are similar enough to allow enough to allow theory from one domain to be used for the other. Considering the crucial differences between both ecosystems this seems unlikely.

The upper water column has a very dominant vertical gradient in light availability and nutrient concentration, i.e. a limited range of resources, but supports more species (especially the micro- and picoplankton) than one might expect. This was called the paradox of the plankton by limnologist GE Hutchinson (1959) and was later applied to the marine environment by Margalef (1968). However, no studies have attempted to define resources in the sea at the same level of detail as is customary in the terrestrial environment. Overall, the smaller number of marine species make it reasonable to assume that the mechanisms of diversity generation and maintenance are different on land and sea.

Goods

Marine organisms play a crucial role in almost all biogeochemical processes that sustain the biosphere, and they provide a variety of products which are essential to mankind’s well-being. Goods include marine foods (about 100 million tonnes produced annually) and natural substances, ingredients for biotechnology and pharmaceuticals, and even land (e.g., the carbonate platforms that make up the Bahamas), and these substances are mainly delivered by macroscopic organisms.

The rate and efficiency, as well as the range of goods and services which marine organisms provide, are determined by interactions between organisms, between organisms and their environment and therefore by biodiversity. These relationships have not yet been quantified and we are at present unable to predict the consequences of loss of biodiversity in ecological, economic or social terms.

Services

Besides goods, marine ecosystems deliver services that are essential to the proper functioning of the Earth. These services include regulation of climate, production and mineralisation of organic material, storage of carbon, storage and detoxification of pollutants and waste products from land, buffering of climate change, coastal protection (mangroves, dune-beach systems, coral reefs) and regulation of biogeochemical cycles in general.

Spanish hogfish at a coral reef © NOAA

Two examples of major processes involving carbon and nitrogen are primary production and nitrogen fixation. A limited number of microscopic species account to a large extent for the magnitude of these processes. It is not clear what impact human activity may have on the biodiversity of micro-organisms in the open sea, or what the consequences might be.

Multi-disciplinary approach

When this simple picture holds – i.e., that overall the goods in the oceans are provided by macro-organisms and the services by micro-organisms – it is clear that the marine food web should be a central point of attention and research to clarify the consequences of human activity. Only in a multidisciplinary approach can we hope to understand what the interactions between species and biogeochemical cycles really mean in terms of global change.

Valuation

The economic value of harvestable marine biodiversity is very high, and the valuation of goods and services has been the subject of much research and debate. Although it is possible to attribute monetary value to many goods and services and to show that this value can be extremely high, it is also important to recognize that non-use values such as intellectual interest, aesthetic pleasure and a general sense of responsibility towards the non-human life of our planet are important requirements for public support of the conservation and sustainable use of the marine environment. A discussion on biodiversity as valuation concept can be found in the articles Marine biological valuation and Cultural value variation.

Conservation

Loss of marine biodiversity has been documented extensively for larger vertebrate and a few invertebrate species which are directly exploited by man. One of the most spectacular examples is the loss of diversity in pelagic fish due to the long-line fisheries of a number of nations. Marine turtles worldwide, including in Europe, have undergone dramatic declines.

Only a few marine species have gone completely extinct, as far as we know. Still, the threat is there and protection of marine species and conservation of marine areas are on the political agenda and have been for many years.

An overview of threats for marine biodiversity can be found Threats to Marine Biodiversity.