Why is Marine Biodiversity Important?
As reviewed by Norse (1995), understanding marine biodiversity is very important for a number of reasons. One could argue that marine biodiversity has innate importance, as life has value on its own. If one considers how long life on earth has been in existence (some 3 billion years), it is apparent that the earth has been working (through evolution) on the present day biodiversity for a long time. It is possible that we have little right deciding the fate of biodiversity in the first place. All ethics aside, however, the importance of marine biodiversity falls into a few categories:
- Raw Materials
Biodiversity allows the environment to adapt to changing conditions, as has been the case since life was created. Humans have acted to increase the rate of deterioration and consequently, it will be a great challenge for the marine environment to adapt rapidly enough in the future. These changes have been induced through pollution, fishing, sediment deposition and alteration of the global climate (Norse, 1995). Considering the present human impact on the environment, it is ironic that without genetic diversity, natural selection cannot occur. If natural selection is limited, then adaptation is impossible. Thus, it is evident that the preservation of biodiversity and more specifically, genetic diversity is of paramount importance if we are to allow proper adaptation to our rapidly changing environments.
Food is a very important commodity that can be provided by our oceans including fishes, invertebrates and algae. Finfish and shellfish are the greatest source of animal protein especially for developing countries (Norse, 1995). Very few of the world's fish are utilized commercially and thus, the oceans are a source for unutilized resources. Seaweeds are also very important commercially, historically being extremely important in East Asia. Some examples include giant kelp, nori and agarweed. Conserving biodiversity of these groups will allow the use of unutilized resources in the future. Furthermore, a diverse ocean could potentially help to alleviate current and future commercial fishing pressures.
The potential for acquiring future raw materials from the ocean is enormous. These materials include medicines, polysaccharides, feed for livestock and building materials.
Natural medicines began and continue to be discovered through the wealth of diversity on the planet. Although most medicines originate from sessile land plants, the ocean hosts many sessile animals that defend themselves through chemical means. Furthermore, the marine realm hosts a higher biochemical diversify resulting from the high phyletic diversity present in these waters. It is possible that chemicals for pharmaceuticals could be obtained from these organisms which use these substances for defense. An example includes the extract (arabinosides) collected from the sponge Tethya crypta, which is utilized to treat herpes (Norse, 1995 and references therein).
Polysaccharides for human uses are provided by seaweeds including red, brown and green forms. An example includes alginate, which is obtained from brown algae. Seaweeds can also be important in agriculture as feed for livestock, or compost for farm land. It will be important, however, to be certain that this collection is sustainable, as unsustainable seaweed collection has proven detrimental in some areas of the world.
Building materials could be acquired through coral rock and coral sand however this must be accomplished in a sustainable manner. Furthermore, chiton from shrimp and crab shells are used in agriculture as well as human and food supplements (Norse, 1995). The beneficial thing about the use of these shells is that less of the animal is wasted from the fishery alone.
Ecosystems are one of the most important factors that control the global climate. The biogeochemical cycling of gases is greatly controlled by the living biota existing on earth of which the marine realm is extremely important. For example, marine plants and animals aid in controlling carbon dioxide in the ocean, as phytoplankton remove it from the surface waters while releasing oxygen. Subsequently, when phytoplankton die, they sink and add to the supersaturation of carbon dioxide in the deep sea. This results in a vertical gradient of CO2 in the ocean, which has been termed the 'Biological Pump.'
Any impact on marine phytoplankton or other biota could disrupt the biological pump and create a loss of the efficiency of CO2 sequestering by the deep sea. In turn, this loss could lead to an increase of CO2 in the atmosphere. It is already well known that CO2 levels in the atmosphere have been increasing ever since the industrial revolution. Given that these levels are already high, a further increase due to a loss of efficiency of the biological pump is not desirable. Thus, preserving the diversity of these organisms could be essential in controlling the levels of CO2 in the atmosphere.
Preserving marine biodiversity for the sake of knowledge itself is important. For example, there are a number of marine ecosystems that continue to be discovered in the present day. Hydrothermal vents were discovered only in 1976 after an expedition on the Alvin submersible. Most species are endemic to these vents and they include tubeworms, giant clams, mussels, crabs, polychaetes and gastropods. Although the amount of research conducted at hydrothermal vents has resulted in an extensive information base, a lack of knowledge exists in areas such as the factors that regulate community structure, relative importance of local processes (e.g. dispersal), the existence or lack of 'climax' communities and larval dispersal (Metaxas, 2000; personal communication).
In accordance with recent marine ecosystem discoveries, is the detection of a number of new species. For example, in the open ocean, a group of marine free-living bacterial primary producers (prochlorophytes) were not discovered until the late 1980s, however, they account for almost 40 % of the chlorophyll in some ocean areas (Chisholm et al, 1988; R.J. Olsen et al, 1990). The dearth of knowledge on marine microbes is extensive, however, present molecular techniques are assisting science in understanding these very integral components of marine food webs. Microbes are extremely essential in the biogeochemical cycling of many nutrients and they are responsible for much of the recycling of organic matter in the sea (NRC, 1995).
Furthermore, there is so much that we believe we understand when in reality, our current stage is at its infancy. For example, in marine environments, it has recently been discovered that many organisms previously thought to be one species are actually more than one (NRC, 1995 and references therein). One of the best known examples is the mussel Mytilus edulis, which is currently known to be three distinct species (McDonald et al, 1992). Mytilus edulis was used as a monitoring tool in the "International Mussel Watch Program" and it was concluded that impacts of contamination may actually have been attributed to the different growth rates of at least two of the cryptic species (Lobel et al, 1990). Secondly, the marine worm Capitella, which has previously been used as an indicator of pollution impact, is actually 15 or more sibling species (NRC, 1995 and references therein). Thus, using sibling species without realizing it can have many implications for our understanding of the ecology surrounding these animals and thus, could result in inaccurate estimations of commercial resources. This has already occurred with the Spanish mackerel, Scomberomorus maculates, now known to be two species, which mature at different ages and sizes (Collette et al, 1978).
Chisholm, S.W., Olsen, R.J., Zettler, E.R., Goericke, R., Waterbury, J.B. & Welschmeyer, N.A. 1988. A novel free living prochlorophyte abundant in the oceanic euphotic zone. Nature. 334: 340-343.
Collette, B.B., Russo, J.L., & Zavala-Camin, L.A. 1978. Scomberomorus brasiliensis, a new species of Spanish mackerel from the western Atlantic. Fish. Bull. 76: 273-280.
Lobel, P.B., Belkhode, S.P., Jackson, S.E. & Longerich, H.P. 1990. Recent taxonomic discoveries concerning the mussel Mytilus: Implications for biomonitoring. Arch. Environ. Contamin. Toxicol. 19: 508-512.
McDonald, J.H., Seed, R. & Koehn, R.K. 1992. Allozymes and morphometric characters of three specis of Mytilus in the Northern and Southern Hemispheres. Mar. Biol. 111: 323-333.
Norse, E.A. 1993. Global marine biological diversity: A strategy for building conservation into decision making. Island Press, Washington D.C.383 pp.
National Research Council. 1995. Understanding marine biodiversity: A research agenda for a nation. National Academy Press, Washington D.C. 114 pp.
Olsen, R.J., Chisholm, S.W., Zettler, E.R., Altabet, M. & Dusenberry, J. 1990. Spatial and temporal distributions of prochlorophyte picoplankton in the North Atlantic Ocean. Deep-Sea Research. 37: 1033-1051.