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Glossary

It is not MARINET's intention to confuse readers of our website with jargon. However it is sometimes necessary to use technical or scientific terms with which the ordinary person may not be familiar. Therefore we have provided here a definition of some of the words which you will encounter. Should you come across words which we have not included in this glossary, and which are not explained in a standard dictionary, then please do not hesitate to bring them to our attention and we will include them in our listing.

• bathymetric Ξ noun: Bathymetry, the depth of the seabed, analogous to topography (on land). A bathymetric reading or survey is therefore a measurement of the depth of the seabed. Such a survey is usually conducted acoustically.
• benthic Ξ noun: Benthos, the plants and animals which live on the seabed.
• biomass Ξ the amount of living matter. This is therefore a different measure to numbers of organisms. So, for example, there is much more biomass in 1 elephant than there is in 1000 fleas and there may be more biomass in 100 large cod than you would find in 150 small (because of over fishing) cod.
• biodiversity Ξ biological diversity in an environment as indicated by numbers of different species of plants and animals.
• biotope Ξ a discrete physical habitat with its associated community of animals and plants.
• cnidarians Ξ are a class of marine animals which include sea anemones, corals, hydroids, sea pens and sea firs, and jellyfish. Cnidarians are distinguished by the fact that they possess stinging cells which are used both for defence and the capture of prey. These stinging cells contain a long, hollow, coiled thread which shoots out and uncoils under water pressure. Discharge is triggered by touch or chemical stimulus. The threads have different functions. Some simply entangle their prey, whilst others stick to it or inject poison. Most cnidarians have a two-stage lifecycle. In one of these the animal takes the form of a polyp where it has a tubular body fastened to hard surfaces whilst during the alternate, known as the medusa stage, the animal is free-floating and swims in the sea. Sea anemones, for example, are usually encountered in their polyp stage; whereas jellyfish are usually encountered in their medusa stage.
• conspecific Ξ of the same species
• demersal Ξ living on the seabed
• diatom Ξ a major group of eukaryotic algae (eukaryotic organisms are known as eukaryotes and are organisms whose cells are organized into complex structures enclosed within membranes), and diatoms are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons (e.g. Fragillaria), fans (Meridion), zigzags (Tabellaria), or stellate colonies (Asterionella). A characteristic feature of diatom cells is that they are encased within a unique cell wall made of silica (hydrated silicon dioxide) called a frustule. These frustules show a wide diversity in form, some quite beautiful and ornate, but usually consist of two asymmetrical sides with a split between them, hence the group name. Fossil evidence suggests that they originated during, or before, the early Jurassic Period. Diatom communities are a popular tool for monitoring environmental conditions, past and present, and are commonly used in studies of water quality.
• draw down Ξ the process by which tides and wave motion remove (draw down) material from a beach and pull it out to sea. A sandy beach experiencing draw down is thus denuded of its sand. The process can be natural (i.e. winter storms) or can be artificially caused (e.g. aggregate dredging, whereby the dredging of sand and gravel offshore causes sand to be drawn down from the beach in order to replace the material which has been dredged).
• echinoderms Ξ spiny-skinned animals which live in the sea, their bodies generally displaying radial symmetry e.g. starfish, sea-urchins, brittlestars, sea-cucumbers. These animals have a "water vascular system" which communicates with the surrounding sea water and operates, by means of hydrostatic pressure, rows of radially arranged suckers. These suckers are known as "tube-feet".
• ecosystem Ξ the complex of a community of organisms and its environment functioning as an ecological unit.
• ecosystem approach Ξ An ecosystem-based approach to management represents a new and more strategic way of thinking. It puts the emphasis on a management regime that maintains the health of ecosystems alongside appropriate human use of the marine environment, for the benefit of current and future generations. This requires setting clear environmental objectives both at the general and specific level, basing management of the marine environment on the principles of sustainable development, conservation of biodiversity, robust science, the precautionary principle and stakeholder involvement.
  Ref, DEFRA, Safeguarding Our Seas, section 1.17 (2002)
• EU Habitat Directive Ξ In May 1992, the member states of the European Union adopted the 'Council Directive 92/43/EEC on the conservation of natural habitats and of wild fauna and flora'. This is more commonly referred to as the Habitats Directive. The main aim of the Directive is to promote the maintenance of biodiversity and, in particular, it requires member states to work together to maintain or restore to favourable conservation status certain rare, threatened, or typical natural habitats and species. These are listed in Annex I and II respectively. One of ways in which member states are expected to achieve this aim is through the designation and protection of a series of sites, known as Special Areas of Conservation (SACs). See the following website for further details about marine SACs www.ukmarinesac.org.uk/ms1.htm
• eutrophic Ξ water (freshwater or saline) is said to be eutrophic when all normal life in it has died due to oxygen starvation. The process is usually caused by excess nutrients present in the water which causes an explosion in algal species (known as an algal bloom). As this algal bloom dies the decaying plant material (algae) falls to the bed of the watercourse where it is consumed by bacteria. This abundance of decaying material in turn causes a population explosion in the bacteria. However, bacteria (unlike plants) consume oxygen and the population explosion of bacteria strips all the dissolved oxygen out of the water with the result that all other aquatic species who are reliant on the dissolved oxygen for breathing (e.g. fish, larvae, insects) are asphyxiated and die. When this process occurs, a body of water is said to eutrophic. A body of water that is partially eutrophic is where this process (oxygen starvation) has fallen short and/or not yet reached its fullest extent.
• food web Ξ the totality of interacting food chains in an ecological community
• gene Ξ A string of the DNA (deoxyribonucleic acid) molecule that is the fundamental unit of inheritance, so it is variations in the make up of this molecule in the gene that controls variations in an organism's appearance and behaviour. Genes are found in the nucleus of the organism's cells.
• hydroids Ξ Hydroids, or sea-firs, are plant-like animals. They resemble fir-like plants, but are actually the simplest of stinging-celled animals. The cells of these animals contain capsules (called cnidae), and these capsules contain a long hollow, coiled thread which uncoils and shoots out under water pressure when the cell is triggered by touch or water pressure. These threads, whose precise characteristics vary according to species, capture the prey.
• ICZM Ξ Integrated Coastal Zone Management
• littoral sediment flow Ξ This is the flow or movement of sediment (sand, shingle or pebbles) along a beach or coastline. The flow or direction of movement is usually determined by the tidal and wave regime dominant in the area.
• macrobenthos Ξ animals and plants living on the seabed which are sufficiently large to be retained by a 500 micrometre sieve (1 micrometre = one-millionth of a metre, see meiofauna). The animals and plants in the macrobenthos are surveyed by all environmental assessments, although often the retaining sieve measures 1 millimetre rather than 500 micrometres. The macrobenthos includes all classes of marine animal and plant. Macrofauna is the term that applies to marine animals alone.
• meiofauna Ξ Marine animals sized between 1 mm and 0.1 mm.
• microfauna Ξ Marine animals smaller than 0.1 mm and, generally speaking, not visible to the naked eye.
• Modiolus modiolus Ξ The horse mussel Modiolus modiolus forms dense beds at depths of 5-70 m in fully saline, often moderately tide-swept areas off northern and western parts of the British Isles. Although it is a widespread and common species, true beds forming a distinctive biotope are much more limited and are not known south of the Humber and Severn estuaries. Off North Sea coasts occasional beds occur between Berwickshire and the Humber, and probably elsewhere.
  M. modiolus is a long-lived species and individuals within beds are frequently 25 years old or more. Juvenile M. modiolus are heavily preyed upon, especially by crabs and starfish, until they are about 3-6 years old, but predation is low thereafter.
  There have been no studies of the recovery of damaged beds but full recovery after severe damage would undoubtedly take many years at best and may not occur at all.
• morphology Ξ the science of form. In biological terms, it is the area of knowledge which deals with the form of plants and animals.
  Hence coastal morphologists - (sometimes referred to as coastal geomorphologists) : those espousing or dealing with coastal geomorphology, in our treatise the changes of our coastline.
• multidecadal Ξ over many tens of years
• Natura 2000 Ξ a European network of protected sites developed to maintain or restore natural habitats and species of wild flora and fauna to favourable conservation status within the European Union.
• Ophiura brittlestar Ξ Brittlestars are marine creatures (see Echinoderms) which live on the seabed, and are of the same class of animals as starfish. There are several species of brittlestar and, as a class, brittlestars are known to date back to the last Ice Age. Brittlestars tend to live in dense communities on the seabed, and amongst some species the density is 100s to 1000s per square metre. The animals live on tide-swept seabeds where the surface is either rocky or of mixed substrata, and they link their "arms" together in order to secure their position on the seabed, whilst other "arms" are raised in order to filter and catch food from the passing water. Brittlestars tend to be a "keystone species" i.e. other marine species live in association with them and are dependent upon them for some essential function (i.e. food, shelter). Ophiura brittlestars are a particular species. They live in communities, but not at the same density as some other brittlestar species. Ophiura brittlestars tend to live in the North Sea where many other species of brittlestar are not to be found.
• pelagic Ξ living in the mid or surface water levels of the sea
• Phaeocystis Ξ Phaeocystis, full name Phaeocystis Pouchetti, is a non-toxic marine plankton algae that once appeared in small amounts along on our beaches in early July, in response to the warmer sea and higher lighting level. At the end of it's life it decays to give a brown flecked foam causing people to think it is sewage along the shoreline. It isn't, but it is brought to into being by the high concentration of nutrients coming from sea going sewage outfalls, added to by agricultural leach off.
  It gives off the characteristic odour of di-methyl suphide on decay, which in the presence of oxygen and sunlight turns to sulphur dioxide and sulphur trioxide. That from the sea is responsible for 30% of the acid rain that falls in northern Europe. It has been forming earlier each year, and now often forms walls over 2 metres high along the beach edge as early as April.
  Children love to play in it. But beware - it can produce an irritating rash in allergic youngsters.
• phytoplankton Ξ microscopic marine plants, usually algae. These microscopic plants are at the base of the food chain, and are the food of zooplankton (microscopic marine animals). Note: phytoplankton are microscopic plants, and zooplankton are microscopic animals.
• pathogens Ξ a virus or bacterium capable of causing disease.
• phylum Ξ a technical term used in the classification of plants and animals relative to one another. It means a primary division or "sub-kingdom" amongst those animals and plants which are considered to be related.
• plankton Ξ Picture shows an assortment of marine diatoms, these being phytoplankton, a light dependent group.
  Plankton is a generic term for a wide variety of the smallest yet most important organisms form that drift in our oceans. They can exist in larger forms of more than 20cm as the larval forms of jellyfish, squid, starfish, sea urchins, etc. and can be algae, bacterial or even viral down to as small as 0.2µm. They are nutrient and light dependent, and form the essential foodchain baseline for larger dependent aquatic lifeforms. Fish species rely on the density and distribution of zooplankton to coincide with first-feeding larvae for good survival of their larvae, which can otherwise starve. Man-made impacts such as dredging, dams on rivers, waste dumping, etc can severely affect zooplankton density and distribution, which can in turn strongly affect larval survival and thus breeding success and stock strength of fish species and the entire ecosystem. They also form the essential basis of CO2 take up in our seas ecosystem, hence Global Warming.
• planktonic Ξ free-floating, drifting.
• polychaetes Ξ a class of worm which lives in the seabed, characterised by numerous bristles on the footstumps.
• RAMSAR Ξ The Convention on Wetlands is of International Importance especially as Waterfowl Habitat http://ramsar.org (Ramsar Convention or Wetlands Convention) was adopted in Ramsar, Iran in February 1971 and entered into force in December 1975. The Convention covers all aspects of wetland conservation and wise use. The Convention has three main 'pillars' of activity:
  • the designation of wetlands of international importance as Ramsar sites www.wetlands.org/RDB/quick.html
  • the promotion of the wise-use of all wetlands in the territory of each country
  • and international co-operation with other countries to further the wise-use of wetlands and their resources.
  The Convention's Contracting Parties have assumed a wide range of related obligations. As of December 2003 there were 138 Contracting Parties to the Convention http://ramsar.org/key_cp_e.htm, with 1,328 Ramsar sites covering over 111 million hectares.
• Sabellaria spinulosa Ξ Also known as the Ross Worm, this is a marine species of worm living in the seabed and building tubes of sand in which it lives. Usually encountered as individuals, this species sometimes behaves gregariously and, when it does so, the tubes which it builds can concrete and form sizeable structures on the seabed of several centimetres thickness, and these structures can persist for many years. These structures are known as "biogenic reefs" and are particularly important because they form a habitat (see, Biotope) around which many other marine species begin to live (i.e. the habitat affords shelter and food). These "reefs" can occur where the substrata of the seabed is made of sand, pebbles or gravel, and the Sabellaria spinulosa reefs are classified as an Annex I habitat under the EU Habitats Directive, 92/43/EEC. An Annex I habitat is subject to conservation measures, amongst which are that the habitat must be maintained in a favourable condition.
• SAC Special Areas of Conservation Ξ See EU Habitat Directive
• sessile Ξ permanently attached or established; not free to move about
• shoal Ξ a sandbank or sandbar that makes the water shallow
• SMP Ξ Shoreline Management Plan
• species Ξ a category of biological classification comprising organisms or populations potentially capable of interbreeding.
• SSSI Ξ Site of special scientific interest
• stochastic Ξ involving chance or probability, often referring to random "natural" variation
• sub-littoral Ξ below the level of the lowest tides
• tidal range Ξ the difference in height between high and low tide
• tidal stream Ξ the flow of water through channels or around coastlines as a result of tidal water movement
• trophic level Ξ one of the hierarchical strata of a 'food web' (see definition above) characterized by organisms which are the same number of steps removed from the plant or algal life (primary producers) at the bottom. So if grass is the primary producer and both bison and gazelle eat the grass then bison and gazelle are on the same trophic level. Lions and cheetah that eat bison and gazelle would also be on the same level, above bison and gazelle. This is a very simplistic example of trophic levels in a "food web" - in nature, especially when it is healthy, they are much more complex and contain many more trophic levels.
• zooplankton Ξ Zooplankton form the group of tiny animals such as miniscule jellyfish and rotifers present in the marine environment. They are a major source of food for those higher up the food chain, and their numbers relate directly as a good indicator to the nutrient enrichment of the sea of the area.
  Note: phytoplankton are microscopic plants, and zooplankton are microscopic animals.