A mussel shell showing the nacre or mother-of-pearl layer.

nacre - the irridescent innermost layer of a molluscan shell that is secreted by the mantle. It is also called the mother-of-pearl layer

NACRI (Netherlands Antilles Coral Reef Initiative) - NACRI was established in 2000 as part of an effort to improve nature conservation and management in the Netherlands Antilles in general, and specifically targeting coral reefs in order to give more attention to, and better coordinate protection of the coral reefs of the islands. Beginning in 2004, NACRI plans to establish a central monitoring node and database for the Netherlands Antilles as part of the Global Coral Reef Monitoring Network (GCRMN), to complement other existing sub-regional nodes in the Caribbean. A catch survey of reef fisheries in all islands is also planned. The Netherlands Antilles consists of five islands in the Caribbean: Bonaire and Curacao just over 100 km off the Venezuelan mainland, and Saba, St. Eustatius and St. Maarten about 900 km to the north-east in the arc of the Lesser Antilles. The Netherlands Antilles is a so-called territory of the Kingdom of the Netherlands, although it is an independent state

naked skin - pertains to a fish whose body lacks scales; scaleless

nanobiology - biological studies at the extremely small to molecular levels. Many fundamental biological functions are carried out at the level of molecular machineries that have the sizes of 1-100 nm. The emergence of nanobiology allowed understanding of the functions of  these machineries, with the invention of nano- technology, e.g., scanning probe microscopy, modern optical techniques, and micro- manipulating techniques

nanometer - a unit of length equal to 0.001 microns (one thousandth of a micron), 0.000001 millimeters, or 0.000000001 meters; also called a millimicron

nanoscience - the extension of existing sciences into the realms of the extremely small, as in nanomaterials, nanochemistry, nanobiology, nanophysics, nanoengineering, etc

nape - the area behind the head of a fish, extending from the back of the skull to the origin of the dorsal fin

nare - nostril; an opening, external and internal, of the nasal passage. Nares (pl) in fishes lead to blind olfactory sacs and do not connect with an internal passageway. There is an incurrent aperture and an excurrent aperture. Movement of water into the olfactory sacs is for smelling rather than respiration

NARS (Natural Area Reserve System) - the State of Hawai‘i created the Natural Area Reserves System, or NARS, to preserve and protect representative samples of Hawaiian biological ecosystems and geological formations. The diverse areas found in the NARS range from marine and coastal environments to lava flows, tropical rainforests, and even an alpine desert. One can find rare plants and animals within these areas, many of which are on the edge of extinction. The reserves also protect some of the major watershed areas which provide vital sources of fresh water

nasal - pertains to the nose

natant - swimming or floating

National Biological Information Infrastructure (NBII) - a broad, collaborative program to provide increased access to data and information on the nation's biological resources. The NBII links diverse, high-quality biological databases, information products, and analytical toolsmaintained by NBII partners and other contributors in government agencies, academic institutions, non-government organizations, and private industry

National Marine Protected Areas Center - the National Marine Protected Areas (MPA) Center’s mission is to facilitate the effective use of science, technology, training, and information in the planning, management, and evaluation of the nation’s system of marine protected areas. The MPA Center, located within the National Oceanic and Atmospheric Administration (NOAA), develops operational and program policy, supports the MPA Federal Advisory Committee, manages national, regional, and international MPA coordination, conducts outreach and education, consults with federal agencies, state agencies, tribal agencies, fishery management councils, and others, maintains the U.S. MPA website, and oversees the collection of data for the marine managed areas inventory

native species - a species that occurs naturally in a given area. Therefore, one that has not been introduced by humans either accidentally or intentionally; also called an indigenous species

natural climate record - a record of climatic events found by examining the natural environment (e.g., coral growth bands, tree rings, layers of ice in glaciers)

natural selection - a natural process by which organisms (and their genes) that adapt to their environment survive while those that do not adapt become eliminated progressively

NAUI ( National Association of Underwater Instructors) - a scuba diving certifying and instruction agency

nauplius larva - a free-swimming, planktonic larval stage of many crustaceans

nautical chart - a chart used to navigate bodies of water

nautical mile - the length of a minute of arc, 1/21,600 of an average great circle of the Earth. Generally one minute of latitude is considered equal to one nautical mile. The accepted United States value as of 1 July 1959 is 1,852 meters (6,076.115 feet)

Navassa - a small (35 km2) isolated and uninhabited island located at 18o25'N, 75o05'W, approximately 55 km west of the Tiburon Peninsula of Haiti and 220 km northeast of Jamaica. Navassa was designated as a United States National Wildlife Refuge in 1999. Corals and sponges grow on large underwater rocks that have broken off from the cliffs

navicular - boat-shaped

naviform - boat-shaped

NCBI (National Center for Biotechnology Information) - established in 1988 as a national resource for molecular biology information, NCBI creates public databases, conducts research in computational biology, develops software tools for analyzing genome data, and disseminates biomedical information - all for the better understanding of molecular processes affecting human health and disease. NCBI is a division of the National Library of Medicine (NLM) at the National Institutes of Health (NIH)

neap tide - a tide that occurs when the difference between high and low tide is least; the lowest level of high tide. Neap tide comes twice a month, in the first and third quarters of the moon

necrolysis - the decomposition of an organism's body after it dies

necromass - the weight of dead organisms, usually expressed per volume of water or per unit of land surface or volume

necrophagy - feeding on dead animals or carrion

necropsy - an examination and dissection of a body of a dead organism in order to determine the cause of death or changes produced by disease

Elkhorn coral, suffering from recent necrosis. (Photo: U.S. Geological Survey)

necrosis - the death of living tissues due to infection or injury

nectophore - a highly modified medusa that remains with a floating hydrozoan colony and pulsates for locomotion of the colony

Needham's sac - a sac that stores spermatophores in cephalopods

negative binomial regression model - a useful empirical methodology when data are overdispersed, that is, when the variance of the distribution is considerably larger than the mean

negative charge - an electrical charge created by having more electrons than protons.

Fish are a large component of marine nekton. (Photo: Dr. Anthony Picciolo)

nekton - organisms with swimming abilities that allow them to move actively through the water column and to move against currents

nematocyst (cnidocyte) - a specialized stinging cell found in cnidarians

nematode - any unsegmented roundworm of the phylum Nemata, having a tough outer cuticle. The phylum includes free-living forms and disease-causing parasites

Nemertea - a phylum of elongated, often flattened marine worm-like animals comprising nearly 1000 species which range in size from less than an inch to nearly 30 m. They are carnivorous and feed upon annelid worms as well as other marine animals. Their most distinctive structure is a proboscis which is used for food capture, defense, and burrowing into the soft substrate. The sexes are separate in most species and fertilzation is external. Many are capable of reproducing asexually by fragmentation of the body. They are also called "ribbon worms"

neo-Darwinism - the unification of natural selection and Mendelian genetics; also called the Modern Synthesis

neonate - a newborn animal

neoplasm - a cancerous growth

neoprene - a synthetic rubber with good resistance to oil, chemical, and fire. Wet suits and other "rubber" diving accessories used by scuba divers are made of neoprene

neotype - in taxonomy, a specimen selected as type specimen subsequent to the original description in cases where the original holotype, or lectotype, or all paratypes, or all syntypes are lost or destroyed, or suppressed by the Commission (Zoology)

NEPA (National Environmental Policy Act) - passed in 1969, the purposes of NEPA are: to declare a national policy which will encourage productive and enjoyable harmony between man and his environment; to promote efforts which will prevent or eliminate damage to the environment and biosphere and stimulate the health and welfare of man; to enrich the understanding of the ecological systems and natural resources important to the Nation; and to establish a Council on Environmental Quality

nephridium - a simple excretory organ of many invertebrates, consisting of a tube through which waste products pass to the exterior

neritic - refers to the ocean environment landward of the shelf-slope break

neritic zone - the relatively shallow water zone that extends from the high tide mark to the edge of the continental shelf

nerve - a bundle of neurons (nerve cells); specifically, a bundle of axons which are the motor processes of neurons which carry nervous impulses in the direction away from the cell bodies

nerve net - the non-centralized, disorganized network of nerve cells under the epidermis, and sometimes the gastrodermis, of cnidarians. It is comprised of multipolar cells with multiple synaptic junctions, but no polarization. Impulses pass either way across the synapse. Both neuron endings of a synapse have secretory vesicles

nerve net - a diffuse, two-dimensional plexus of interconnected bipolar or multipolar neurons with no central control organ; found in cnidarians

NESDIS (National Environmental Satellite, Data and Information Service) - the NOAA agency that operates and manages the U.S. civilian weather satellites and the national environmental data centers, such as the National Oceanographic Data Center (NODC), the National Climatic Data Center (NCDC), and the National Geophysical Data Center (NGDC)

net photosynthetic rate - the total rate of photosynthetic CO₂ fixation minus the rate of loss of CO₂ during respiration

net primary productivity - the total amount of chemical energy fixed by the processes of photosynthesis minus the chemical energy lost through respiration; same as 'net photosynthetic rate'

network - two or more computers connected together so that they can share resources. Two or more networks connected together is an internet

neuritis - inflammation of the nerves

neuromast - a sensory cell with a hair-like process capable of detecting motion or vibrations in water

A neuron in a mammalian brain. (Photo: University of Kansas Medical Center)

neuron - a nerve cell; a specialized cell that can react to stimuli and transmit impulses. A neuron consists of a cell body which contains the nucleus; dendrites, which are usually short sensory branches off the cell body that receive incoming impulses; and a single, long axon which carries impulses away from the body (motor function) and to the next neuron, gland or muscle

neurophysiology - the branch of neuroscience that studies the physiology of the nervous system

neuropodium - a lobe of the parapodium closer to the ventral side in polychaete worms

neuroscience - the scientific disciplines concerned with the development, structure, function, chemistry, pharmacology, clinical assessments and pathology of the nervous system

neurotoxin - a toxic substance which interferes with the electrical activities of nerves and inhibits, damages or destroys the tissues of the nervous system, especially neurons (nerve cells)

neurotransmitter - a chemical substance ("messenger") produced in and released by one neuron that carries a nervous impulse across a synapse (the small gap between the axon and dendrite of communicating neurons). They relay nervous impulses among neurons and between neurons and other types of cells, such as in muscle and glandular tissues. Neurotransmitters can excite or inhibit another neuron or receptor organ. There are more than 300 known neurotransmitters. A few of the more common ones are acetylcholine, dopamine, norepinephrine, and serotonin

neuston - planktonic organisms associated with the air-water interface

neutralism - the lack of any interaction between two organisms or species in a shared habitat. Neither has any effect on the other

neutrino - a lepton with no electric charge. Neutrinos participate only in weak (and gravitational) interactions and therefore are very difficult to detect. There are three known types of neutrino, all of which have very low or possibly even zero mass

NGO (Non-governmental Organization ) - a non-profit group or association organized outside of institutionalized political structures to obtain particular social objectives (such as environmental protection) or serve particular constituencies

niche - the role of an organism in an ecological community; the environmental requirements and tolerances of a species; sometimes seen as a species' "profession" or what it does to survive

niche overlap - an overlap in resource requirements by at least two species

nictitating eyelid - a movable eyelid found in sharks that can be closed over the eye to protect it from damage. Sharks also have non-moving upper and lower eyelids

nictitating membrane - a semi-transparent membrane which can be drawn across the eye in birds, reptiles and many mammals. It functions to either moderate the effects of strong light or to sweep away dust and similar particles from the surface of the eye

nitrogen narcosis - a hazardous condition that scuba divers may experience at depths usually in excess of 80 ft (24.38 m). It occurs when nitrogen builds up in the body tissues and replaces some of the oxygen required by the brain. The longer a diver with conventional scuba stays at a deep depth, the more nitrogen accumulates. As the brain is deprived of oxygen, the ability to think and function clearly diminishes. It may progress from a slightly confused feeling to an almost intoxicated state, where thinking and judgement is severely impaired. If the diver does not ascend to a shallower depth and off-gas nitrogen, nitrogen narcossis may eventually cause death. Although this can happen at any depth, it is especially a problem with dives in excess of 80 feet. Nitrogen narcossis is also called 'rapture of the deep'

nitrox - any mixture of nitrogen and oxygen that contains less than the 78 percent nitrogen as found in ordinary air

no take zone - a marine protected area that is completely (or seasonally) free of all extractive or non-extractive human uses that contribute impact (some exceptions may be permitted for scientific activities); also called "marine reserve" or "fully protected area"

The National Oceanic and Atmospheric Administration (NOAA) is a federal agency within the U.S. Department of Commerce that is dedicated to predicting, protecting, and providing information about the marine environment.

NOAA (National Oceanic and Atmospheric Administration) - the National Oceanic and Atmospheric Administration (NOAA) is a federal agency within the US Department of Commerce that is dedicated to predicting and protecting the environment. NOAA's overall mission is to understand and predict changes in the Earth+s environment, protect life and property, provide decision makers with reliable scientific information, conserve and manage the Nation+s living marine and coastal resources to meet our Nation+s economic, social, and environmental needs, and foster global environmental stewardship. To achieve its mission, NOAA+s focus through 2008 will be on four mission goals:
1. Protect, restore, and manage the use of coastal and ocean resources through ecosystem-based management
2. Understand climate variability and change to enhance society+s ability to plan and respond
3. Serve society+s needs for weather and water information
4. Support the Nation+s commerce with information for safe, efficient, and environmentally sound transportation

NOAA Coral Reef Conservation Program - a NOAA program whose purposes are: (1) to preserve, sustain, and restore the condition of coral reef ecosystems; (2) to promote the wise management and sustainable use of coral reefs; (3) to develop sound scientific information on the condition of coral reef ecosystems and the threats to such ecosystems; (4) to assist in the preservation of coral reefs by supporting conservation programs, including projects that involve affected local communities and nongovernmental organizations; (5) to provide financial resources for those programs and projects; and (6) to establish a formal mechanism for collecting and allocating monetary donations from the private sector to be used for coral reef conservation projects

NOAA Diving Program - the NOAA Diving Program is administered by NOAA and is headquartered at the NOAA Diving Center in Seattle, WA. The Program trains and certifies scientists, engineers and technicians to perform the variety of tasks carried out underwater to support NOAA's mission. With more than 300 divers, NOAA has the largest complement of divers of any civilian federal agency. In addition, NOAA's reputation as a leader in diving and safety training has led to frequent requests from other governmental agencies to participate in NOAA diver training courses

NOAA's Center for Sponsored Coastal Ocean Research (CSCOR) - NOAA's Center for Sponsored Coastal Ocean Research (CSCOR) develops and improves predictive capabilities for managing the Nation's use of its coastal resources through competitive research programs. CSCOR also supports efforts to translate the results of its research investments, and those of others, into accessible and useful information for coastal managers, planners, lawmakers, and the public to help balance the needs of economic growth with those of conserving the resources of our Nation's Great Lakes, estuaries, and coastal ocean. Its mission is to provide the highest quality research in support of coastal management decisions through competitive, peer-reviewed research and holistic ecosystem studies

NOAA's Coral Reef Conservation Grant Program - each year, subject to the availability of funds, NOAA publishes its Coral Reef Conservation Grant Program Funding Guidance, as authorized by the Coral Reef Conservation Act of 2000, to solicit proposals for coral reef conservation activities. The Act authorizes the Secretary of Commerce, through the NOAA administrator and subject to the availability of funds, to issue matching grants of financial assistance for broad-based coral reef conservation activities, consistent with the purposes of the Act

NOAA's Coral Reef Watch (CRW) Satellite Bleaching Alert (SBA) system - an automated coral bleaching e-mail alert system designed to monitor the status of thermal stress conducive to coral bleaching via the use of the CRW global satellite near-real time HotSpot suite of products.The SBA was developed by the NOAA as a tool for coral reef managers, scientists and other interested people. The SBA became operational in July 2005

NOAA's National Marine Fisheries Service (NOAA Fisheries) - NOAA Fisheries is the federal agency responsible for the stewardship of the nation’s living marine resources and their habitat. It is responsible for the management, conservation and protection of living marine resources within the United States’ Exclusive Economic Zone (water three to 200 miles offshore). Using the tools provided by the Magnuson-Stevens Act, NOAA Fisheries assesses and predicts the status of fish stocks, ensures compliance with fisheries regulations and works to reduce wasteful fishing practices. Under the Marine Mammal Protection Act and the Endangered Species Act, it recovers protected marine species (i.e. whales, turtles) without unnecessarily impeding economic and recreational opportunities. With the help of the six regional offices and eight councils, NOAA Fisheries is able to work with communities on fishery management issues. NOAA Fisheries works to promote sustainable fisheries and to promote sustainable fisheries and to prevent lost economic potential associated with overfishing, declining species and degraded habitats. It strives to balance competing public needs and interest in the use and enjoyment of our oceans’ resources. For more information, see: http://www.nmfs.noaa.gov/

NOAA's National Ocean Service (NOS) - NOS is a scientific and technical organization of NOAA whose mission is to preserve and enhance the nation’s coastal resources and ecosystems along 95,000 miles of shoreline and 3.5 million square miles of coastal ocean. At the same time, it works to support economic growth for the long-term benefit of the nation. This theme is central to the sustainable development agenda of both NOAA and the U. S. Department of Commerce (DOC). For detailed information, see: http://www.oceanservice.noaa.gov/about/welcome.html

NOAA's Office of Oceanic and Atmospheric Research (NOAA Research) - the Office of Oceanic and Atmospheric Research (OAR) or “NOAA Research” works in partnership with NOAA’s National Weather Service, National Ocean Service, National Environmental Satellite Data Information Service and National Marine Fisheries Service as the research and development organization of the agency. It is through NOAA Research that work results in better weather forecasts, longer warnings for natural disasters and an overall greater understanding of our oceans, climate and atmosphere. NOAA Research explores the Earth and atmosphere from the very surface of the sun to the depths of the ocean. Its role within NOAA is to provide products and services that describe and predict changes in the environment. NOAA Research results allow decision makers to make effective judgments in order to prevent the loss of human life and conserve and manage natural resources. Research is conducted, with its partners in academia, in three major areas: atmosphere, climate, and ocean and coastal resources. For more information, see: http://www.research.noaa.gov/

nociceptor - a sensory receptor which responds to potentially harmful stimuli; produces a sensation of pain

nocturnal - being primarily active at night

node - any single computer connected to a network

nodulose - with small nodules, knobs or swellings

noise - unwanted sound

nomen illegitimum - in taxonomy, an illegitimate name; a validly published name that must be rejected for the purposes of priority in accordance with the International Code of Zoological Nomenclature

nomen negatum - in taxonomy, a denied name: an unavailable name which has incorrect original spellings as defined by the International Code of Zoological Nomenclature

nomen novum - in taxonomy, a new name which is published to replace an earlier name (and valid only if the latter is preoccupied) and which is expressly proposed as a replacement name; a new name, not to be confused with a new species, or a new genus, etc., which represent new taxa. It is commonly applied to names proposed to replace junior homonyms

nomen nudum - in taxonomy, a naked name, i.e., a name that, if published before 1931, was not accompanied by a description, definition, or indication, or if published after 1930, is not accompanied by a statement that purports to give characters differentiating the taxon; or is not accompanied by a definite bibliographic reference to such a statement; or is not proposed expressly as a replacement for a pre-existing available name. A nomen nudum is not an available name

nomen nullum - in taxonomy, a null name, i.e.,an unavailable name which, as defined by the International Code of Zoological Nomenclature, is a non-demonstrably intentional change of an original spelling, i.e. a form of incorrect subsequent spelling

nomen oblitum - in taxonomy, a forgotten name; an unused senior synonym rejected under the provisions of the International Code of Zoological Nomenclature

nomen oblitum - in taxonomy, a forgotten taxonomic name

nomen vetitum - in taxonomy, an impermissible name; an unavailable name published for divisions of the genus group other than genus and subgenus, which are not accepted by the International Code of Zoological Nomenclature

nomenclature - the description of new taxa or alterations to the concept of previously described taxa which involve changes in the names of taxa

nominal taxon - in taxonomy, a named taxon, objectively defined by its type taxon. Thus the nominal family Chaetodontidae is always the one to which its nominal type genus, Chaetodon, belongs

nominate subordinate taxon - in taxonomy, a subordinate taxon which bears the same names as its immediate higher taxon. Thus Badis badis is the nominate species of the genus Badis

non-coding linker sequences - short pieces of DNA between genes which do not direct protein synthesis or perform a regulatory function

non-extant - no longer existing

non-point source pollution - a pollution source without a single point of origin, or not introduced into a receiving stream from a specific outlet. It occurs when rainfall, snowmelt, or irrigation runs over land or through the ground, picks up pollutants, and deposits them into rivers, lakes, and coastal waters or introduces them into ground water. Common nonpoint sources are agriculture, forestry, mining, construction, dams, channels, land disposal, saltwater intrusion, and city streets

nonallele - a gene that is not a competitor at the same locus (specific location on the chromosome)  

nonbiodegradable material - a material that cannot be broken into simpler chemicals by living organismss

noncoding DNA - DNA that does not encode any product (RNA or protein). The majority of the DNA in plants and animals is noncoding

nondegradable pollutant - a polluting substance that is not broken down by natural processes

nonessential amino acid - an amino acid which can be synthesized by the organism's body, and not required in the nourishment source. Humans can make 13 nonessential amino acids

nonionizing radiation - radiation that carries enough energy to excite an atom or molecule, but not enough energy to remove an electron from the atom or molecule. This type of radiation does not cause damage to cells and tissues; examples include radio waves, microwaves, infrared light, and ordinary light

nonrenewable resource - an environment resource which is not replaced or replenished by natural processes at a rate comparable to the use of the resource; a resource depleted or exhausted by use

nonseptate - lacking cross walls (septa); also termed "aseptate"

nonvascular plant - a plant which lacks tissues to conduct water and nutrients. Nonvascular plants do not produce flowers or seeds

North Star - Polaris, the North Star, is visible in the northern hemisphere and indicates the direction of north. In the southern hemisphere the Southern Cross is used to find the direction of south

notch - an indentation

notochord - a flexible rodlike structure that forms the supporting axis of the body in the lowest chordates, (e.g., tunicates and lancelets) and lowest vertebrates (e.g., lampreys), and in the embryos of all higher vertebrates, where it is replaced by the vertebral column; a prime defining characteristic of the phylum Chordata

notopodium - a lobe of the parapodium closer to the dorsal side in polychaete worms

NOWRAMP (Northwestern Hawaiian Islands Coral Reef Assessment and Monitoring Program) - a multi-agency, multi-year effort that began in 2000. NOWRAMP's objective is to rapidly evaluate and map the shallow water reef habitats in the NWHI. The agencies which contribute to NOWRAMP are: NOAA, the U.S. Fish and Wildlife Service, the State of Hawai‘i Department of Land and natural Resources, the University of Hawai‘i, the Bishop Museum, the Hawai‘i Maritime Service, the U.S. National Park Service, and scientists from the University of California at Santa Cruz

NPDES (National Pollutant Discharge Elimination System) - a provision of the Clean Water Act (CWA) which prohibits discharge of pollutants into waters of the United States unless a special permit is issued by EPA, a state, or where delegated, a tribal government on an Indian reservation

nuchal - pertaining to the neck

nuchal organ - a sense organ on upper side of head in many branchiopods; photoreceptor-like sensory cells in the nuchal region (posterodorsal region of the head) of some cephalopods; paired chemosensory structures in some annelids

nuclear family - a monogamous mating pair where both male and female partner share in caring for the eggs and young

nuclease - one of the several classes of enzymes that degrade nucleic acid; an enzyme that can degrade DNA or RNA by breaking phosphodiester bonds that link adjacent nucleotides

nucleic acid - a large molecule found in biological cells composed of nucleotide subunits

nucleic acid isolation - a prerequisite for molecular genetic studies is, by definition, the ability to isolate nucleic acids (DNA and RNA)

nucleoprotein - a conjugated protein composed of nucleic acid and protein; chromosomes are composed of nucleoproteins

Diagram of DNA shows nucleotide structure. (Diagram: NIH/Human Genome Project)

nucleotide - one of the structural components, or building blocks, of DNA and RNA. A nucleotide consists of a base (one of four nitrogenous bases: adenine, thymine, guanine, and cytosine) plus a molecule of sugar and one of phosphoric acid

A cell with a large central nucleus. The dark mass within the nucleus are the chromosomes.

nucleus - a central cell structure that contains the chromosomes, and as such, controls the activities of the cell; the center of an atom, containing protons, neutrons, and most of the mass

A Pacific nudibranch. (Photo: Dr. Bill Rudman)

nudibranch - a opisthobranchiate mollusk (sea slugs), having no shell except while very young. The gills are naked and situated upon the back or sides

null hypothesis (Ho) - the statistical hypothesis that states that there are no differences between observed and expected data. The null hypothesis is used in experimental research. It asserts arbitrarily that there is no relationship among the variables being studied. Then statistical tests are used to determine if any relationship shown by the research data is due to chance alone or to alternative hypotheses

numerical taxonomy - study of the relationships of taxa by the application of numerical similarity values to characters so as to rank into categories based on degree of overall similarity

numericlature - an attempt to express the natural order (i.e. classification) of organisms in numbers, so that each taxon name is represented by a numerical code, the structure of which indicates its taxonomic position, rank and affinities

nuptial - a term associated with reproductive or breeding behavior, e.g., nuptial coloration, nuptial tubercles (in fishes)

NURP (NOAA National Undersea Research Program) - a unique national service that provides undersea scientists with tools and expertise that they need to work in the undersea environment. Each year, the program supports 200 or more undersea research projects related to NOAA's mission as steward of oceanic resources and environments. A key strength of NURP is its partnership with the nation's science community, carried out primarily through six regional NURP Centers

nursery - an area favored for birth or egg deposition and where juveniles and immature members of a community feed and grow. For example, mangrove root areas serve as nursery grounds for many coral reef fishes

nutrient - any substance assimilated by organisms that promotes growth. Marine scientists typically measure nitrites, nitrates, phosphates, and silicates as nutrients for plant growth

nutrient cycle - the cyclic conversion of nutrients from one form to another within biological communities

nutrient cycling - all the processes by which nutrients are transferred from one organism to another. For instance, the carbon cycle includes uptake of carbon dioxide by plants, ingestion by animals, and respiration and decay of the animal

nutrient pollution - contamination of water resources by excessive inputs of nutrients. In surface waters, excess algal production is a major concern

nutrient regeneration - the release of nutrients from organic matter by decomposer organisms

Graphic showing location of Northwest Hawaiian Islands

NWHI (Northwestern Hawaiian Islands) - the Northwestern Hawaiian Islands (NWHI) are a chain of small islands, atolls, submerged banks, and reefs beginning approximately 120 nautical miles west of the main Hawaiian islands, and stretching northwest for more than 1,079 nautical miles or 2,000 kilometers. This vast archipelago is uninhabited (except for Midway Island) and is surrounded by some of the most extensive and pristine coral reefs in U.S. waters

Reference map of the Northwestern Hawaiian Islands Ecosystem Reserve. (1) Nihoa Island, (2) Necker Island, (3) French Frigate Shoals, (4) Gardner Pinnacles, (5) Maro Reef, (6) Laysan Island, (7) Lisianski Island, (8) Pearl and Hermes Atoll, (9) Kure Atoll, (10) The First Bank immediately east of French Frigate Shoals, (11) Southeast Brooks Bank (the first bank immediately west of French Frigate Shoals), (12) St. Rogatien Bank, (13) The First Bank immediately west of St. Rogatien Bank, (14) Raita Bank, and (15) Pioneer Bank. (Graphic: NOAA)

NWHI Coral Reef Ecosystem Reserve - the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve was established by Executive Order 13178 in December 2000, and January 2001(Executive Order 13196). It was established to conserve and protect the NWHI coral reef ecosystem and related natural and cultural resources of the area