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Topic: Euphotic zone

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	Euphotic zone -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-09)
		The euphotic zone is the surface layer of the (A large body of water constituting a principal part of the hydrosphere) ocean where sufficient light is available for (Synthesis of compounds with the aid of radiant energy (especially in plants)) photosynthesis.
		It extends from the atmosphere-ocean interface downwards to a depth where light intensity falls to 1% of that at the surface (the euphotic depth), so its thickness depends on the extent of light (The property of something that has been weakened or reduced in thickness or density) attenuation in the water column.
		Typical euphotic depths vary from only several metres in (additional info and facts about turbid) turbid (additional info and facts about estuaries) estuaries to around 200 metres in the open ocean.
	www.absoluteastronomy.com /encyclopedia/e/eu/euphotic_zone.htm (132 words)

	Photic zone - Wikipedia, the free encyclopedia
		The photic zone is the depth of the water, whether in a lake or an ocean, that is exposed to sufficient sunlight for photosynthesis to occur.
		Since the photic zone is the only zone of water where primary productivity occurs, an exception being the productivity connected with abyssal hydrothermal vents along mid-oceanic ridges, the depth of the photic zone is generally proportional to the level of primary productivity that occurs in that area of the ocean,.
		The transparency of water, which affects the photic zone, is simply measured with a Secchi disk.
	www.wikipedia.org /wiki/Euphotic_zone (189 words)

	abstract 4.5 (Site not responding. Last check: 2007-10-09)
		The study has focused on the lower euphotic zone, which is characterized by an accumulation of nitrite (the primary nitrite maximum or PNM).
		The goals of the study were to assess the role of nitrification in the recycling of nitrogen within the euphotic zone of a well-characterized oligotrophic site, to investigate the influence of nitrification on the structure and variability of nitrite distributions and to examine the relationship between nitrification and the production of nitrous oxide.
		Chemiluminescent nitrite measurements revealed that the PNM exhibits a double-peaked structure, with a large upper maximum at a depth of 126 ± 18 m and a lower maximum of lesser magnitude at 149 ± 15 m.
	hahana.soest.hawaii.edu /hot/abstracts/doc4_5.html (427 words)

	Ocean Water: Optics
		The first zone, or euphotic zone, extends from the water's surface to about 50 meters depth, depending on the time of year, the time of day, the clarity (clearness) of the water and the presence of clouds.
		The next zone is the dysphotic zone, which extends from about 50 meters, or wherever the euphotic zone ends, to about 1,000 meters.
		In this zone, there is enough light for organisms to see, but it is too weak for photosynthesis to happen.
	www.onr.navy.mil /focus/ocean/water/optics1.htm (296 words)

	[No title] (Site not responding. Last check: 2007-10-09)
		Flux measurements were compared with weekly samples of suspended pigments in the euphotic zone and bi-monthly samples of total suspended matter and particulate C throughout the water column at the mooring site.
		Bloom-induced changes in the pigment concentration were observed almost simultaneously in the euphotic zone and in the traps to a depth of 160 m, indicating a rapid vertical transfer of surface-originating particles by organic aggregates.
		Budget calculations suggest that the loss of primary-produced C and pigment from the euphotic zone by settling is ~5% regardless of season.
	www.pmel.noaa.gov /pubs/1986abs/0701.html (355 words)

	Aquatic Life
		Eloranta (1978), for example, found that the euphotic zone in freshwater lakes in Finland decreased from 10 m to 4-5 m with an increase in colour from 5 to 20 mg/L Pt.
		Less than 10% change in euphotic zone where water column is greater than 0.5x euphotic zone; for shallower waters, maximum reduction in light at the sediment bed should not exceed 20%.
		Less than 10% change in euphotic zone where depth is greater than 0.5x euphotic zone; for shallower waters, maximum reduction in light at the sediment bed should not exceed 20%.
	wlapwww.gov.bc.ca /wat/wq/BCguidelines/colour/colour-04.htm (3084 words)

	Water ecology FAQ
		The euphotic zone is the upper oceanic zone, where producer species produce oxygen.
		This is the zone on the surface of the lake, extending to the depth where sunlight penetrates.
		Coastal life zones are particularly sensitive to toxic contamination, because they are a dump for pesticides, heavy metals and other pollutants, which will soon accumulate to high levels.
	www.lenntech.com /water-ecology-FAQ.htm (2492 words)

	Ocean Light Zones
		Animals that live in the twilight zone include: lantern fish, rattalk fish, hatchet fish, viperfish, and mid-water jellyfish.
		Ninety percent of the ocean is in the midnight zone.
		Living things in the midnight zone include: angler fish, tripod fish, sea cucumber, snipe eel, opposom shrimp, fl swallower, and vampire squid.
	mbgnet.mobot.org /salt/oceans/zone.htm (257 words)

	YSI 6026 Wiped Turbidity Sensor (Site not responding. Last check: 2007-10-09)
		Euphotic Zone: the lighted zone of a lake or reservoir that extends horizontally from shore to shore and vertically from the surface to the compensation point.
		Light intensity, throughout the euphotic zone is sufficient to support photosynthesis.
		It signifies the bottom or deepest point of the euphotic zone and is also the point at which production and respiration are at equilibrium.
	www.ysi.com /extranet/EPGkL.nsf/447554deba0f52f2852569f500696b21/cce3b71ff049067e85256a9300704e49!OpenDocument (2977 words)

	ocean: The Ocean as a Biological Environment
		The benthic realm is subdivided on the basis of depth into the littoral zone, which extends from high tide to a depth of about 200 m (660 ft), and the deep-sea realm.
		Benthonic animals that live below the euphotic zone often must depend on the rain of organic debris from above to supply their food needs, and thus the deep regions of the benthic realm are not highly populated except in the areas around
		Vertically it is divided into the euphotic, or photic, zone and the aphotic (without sunlight) zone.
	www.factmonster.com /ce6/sci/A0860102.html (466 words)

	A review of the world resources of mesopelagic fish. FAO Fisheries Technical Paper 193:1-151. -
		The oceanic pelagic zone is dominated by the activity of plankton in the euphotic surface waters, Plankton are by definition drifting or weakly swimming organisms, comprising a wide range of small to microscopic animals, protoctists and bacteria.
		With few exceptions, the only food source for creatures in the aphotic zone is the 'rain' of organic matter (faeces, moulted crustacean exoskeletons, corpses) derived from the plankton and nekton.
		It has generally been assumed that biomass in the pelagic zone everywhere below the euphotic zone is low, however, recent studies have indicated that biomass of tropical mesopelagic animals may be surprisingly high.
	www.oceansatlas.org /id/18562 (320 words)

	The MBARI Chemical Sensor Program - Horizontal and Vertical Distributions of Elements in the Ocean
		This process is dominated by plants, which are restricted to the sunlit zone of the ocean where there is enough light for photosynthesis (the euphotic zone).
		The euphotic zone may range from a few meters deep in particle rich coastal waters to 150 m in the clearest ocean waters.
		Much of the biomass produced by these plants sinks from the euphotic zone when they are eaten and excreted by zooplankton or if the plant population exhausts the chemical nutrients in the water.
	www.mbari.org /chemsensor/distribution.html (1197 words)

	DSOcean Supplementary Information
		Most primary productivity occurs in the upper half of the photic zone (the thin surface layer of lighted water that is rarely deeper than 200 m), in the zone called the euphotic zone (meaning good zone).
		The euphotic zone is where plants capture more light energy from sunlight than they require to just make a living (i.e., grow, reproduce) and so can store excess carbohydrates and sugars (inorganic carbon turned into organic or fixed carbon).
		The compensation depth coincides with the depth in the ocean where the light level is 1% to 0.1% of the amount of the sunlight entering the surface of the ocean.
	www.aos.wisc.edu /~hopkins/oceans/spr_04/supl05.html (943 words)

	Information about Dan Clark (Site not responding. Last check: 2007-10-09)
		These measurements were used to test the hypothesis that: Advective and turbulent fluxes of nitrate balance the uptake of nitrate in the euphotic zone of the study region.
		The dominant sources of nitrate to the euphotic zone were found to be the vertical component of both the diapycnal and the along-isopycnal fluxes.
		A comparison of the sources and sinks of nitrate in the euphotic zone leads to a balance within the uncertainties of the estimates.
	www.phys.ocean.dal.ca /people/po/Clark_Dan.html (253 words)

	Biological Pump
		Diel vertical migration is a mechanism by which zooplankton (or nekton) feeding in the surface waters at night actively transport dissolved or particulate material to depth by metabolizing the ingested food at their daytime residence depths.
		The mesopelagic zone, between ~100 - 1000 meters (incorporating mode waters and the main thermocline), is an important focus area for OCTET, and one not addressed by JGOFS, which largely focused on the euphotic zone.
		In addition, part of the reason the "twilight zone" is poorly known is that we do not have the tools to study all the important processes.
	www.msrc.sunysb.edu /octet/biological_pump.html (2001 words)

	Theory of Advective Effects on Biological Dynamics II - Robinson
		The theory of advective effects is extended to include: localization effects due both to the attenuation of light with depth in the ocean, and to nutrient transport into the euphotic zone of finite duration in time, and/or over a limited horizontal domain.
		A general theoretical solution has been obtained for a model ocean in which a dynamically active near-surface euphotic zone overlies a deeper region in which biological material is passively advected by the physical flow field.
		Interesting results are indicated for the location, shape and magnitude of phytoplankton maximum and associated nutricline in the euphotic zone, and for the dynamical mechanism by which phytoplankton mediate the conversion of nutrient to zooplankton biomass.
	people.deas.harvard.edu /~robinson/PAPERS/advec_II.html (3119 words)

	ATLANTIC OCEAN, political, economical, historical, geographical aspect
		The littoral, or tidal, zone is the area along the shore between the high-tide and low-tide levels.
		The euphotic zone is the ocean's surface layer
		About two thirds of the fishes that inhabit this zone are bioluminescent, or capable of producing their own light.
	www.geocities.com /macosmet/atlantic_ocean.html (1653 words)

	Sunlit Ocean (Euphotic) Zone - EnchantedLearning.com
		This bright ocean layer is called the sunlit zone or the euphotic zone (euphotic means "well lit" in Greek) or the epipelagic zone (epipelagic means "upon the sea").
		The depth of this zone depends on the clarity or murkiness of the water.
		The limpet is a marine invertebrate (a gastropod) with a flattened, cone-shaped shell.
	www.enchantedlearning.com /biomes/ocean/sunlit (1873 words)

	CiteULike: The phytoplankton and protozooplankton of the euphotic zone of Lake Tanganyika: Species composition, ... (Site not responding. Last check: 2007-10-09)
		The seasonal cycle of phytoplankton and protozooplankton 1 iomass observed at two widely separated pelagic stations in the euphotic zone of Lake Tanganyika from February through November 1975 could be divided into three phases, based oil algal abundance and species succession and coinciding with three phases of annual thermal stratification.
		Phytoplankton biomass was minimal (as low as 60 mgm-“) during the phase of stable stratification and maximal, as high as 930 mg me 3, at the end of the period of deep mixing.
		Chlorophyll a ral.nged from 0.1 to 4.5 mg* np3 in he ellphotic zone and frorn 0.2 to 20.4 in surface waters; phytoplankton biomass ranged frctm 25 to 1,570 rng.n+ in the cuphotic zone.
	www.citeulike.org /user/Tarbe/article/383530 (364 words)

	New Production from remotely Sensed Temperature and Chlorophyll
		The sinking of organic material produced by photosynthesis from the upper euphotic layers into the oceans represents a potential long-term sink for atmospheric CO This sequestration of carbon into the ocean’s interior is termed the ‘biological pump’ and plays a central role in the global carbon cycle.
		Its magnitude is regulated by the supply of inorganic nitrogen, primarily nitrate to the euphotic layer.
		Hence, understanding the spatial and temporal variations of N over basin and global scales in the euphotic zone is an important requirement for ocean biogeochemical and climate studies.
	www.bigelow.org /elnino/np.htm (700 words)

	ATM S 211 - Fall 2001
		Hence, the sunlit 'euphotic zone' is restricted to the uppermost few tens of meters.
		Plankton 'blooms' would use up all the available nutrients in the euphotic zone within a matter of days if there were no way of replenishing the supply.
		The zone is narrow because the phytoplankton growing in the upwelled water go through their life cycle in just a day or two-- not long enough for the upwelled water to diverge more than a few tens of km from the equator.
	www.atmos.washington.edu /2001Q4/211/notes_marinebiosphere.html (1261 words)

	Diffusion
		In aquatic ecosystems, photosynthesis occurs in the euphotic zone, the upper layers in which light intensity is sufficent for photosynthesis to exceed respiration.
		Some process is needed to return P to the euphotic zone, in order for life in this zone to continue.
		After the organic material falls below the euphotic zone, it will eventually be oxidized, and the phosphorus will enter the sea water in the form of phosphate ion.
	www.cco.caltech.edu /~brokawc/Bi145/Diffusion.html (1796 words)

	photic zone -- Encyclopædia Britannica (Site not responding. Last check: 2007-10-09)
		The uppermost 80 m (260 feet) or more of the ocean, which is sufficiently illuminated to permit photosynthesis by phytoplankton and plants, is called the euphotic zone.
		Sunlight insufficient for photosynthesis illuminates the disphotic zone, which extends from the base of the euphotic zone to about 200 m.
		For example, some types of plankton, fish, and squid remain beneath the photic zone during the day, moving toward the surface after dusk and returning to the depths before dawn.
	www.britannica.com /eb/article-9059790?tocId=9059790 (747 words)

	Larvacea - Wikipedia, the free encyclopedia
		The Appendicularia or Larvacea are a group of free-swimming pelagic urochordates found throughout the worlds oceans.
		Appendicularians are filter feeders that primarily occupy the euphotic zone (upper sunlit portion of the ocean) but some species can be found in deeper waters.
		The morphology of appendicularians superficially resembles that of the tadpole larvae of most urochordates as they possess a discrete trunk and tail throughout adult life.
	en.wikipedia.org /wiki/Larvacea (372 words)

	En-Ez
		The sharp transition zone between the planetary boundary layer and the free atmosphere in the interfacial region between cloud and no-cloud in the atmosphere.
		A division of the NESDIS branch of NOAA whose mission is to conduct an integrated program of fundamental research, related technology development, and services to improve understanding and prediction of the geophysical environment consisting of the oceans and inland waters, lower and upper atmosphere, the space environment, and the Earth.
		It is a zone with sharp gradients in illumination, temperature and salinity, and is the upper of three vertical zones that comprise the pelagic part of the ocean, the other two being the middle mesopelagic and the lower bathypelagic zones.
	stommel.tamu.edu /~baum/paleo/paleogloss-old/node12.html (3853 words)

	Physical and biological processes controlling the export flux and mineralization of carbon
		Studies in the Gulf of St. Lawrence are characterizing the biologically mediated export of carbon from the euphotic zone and exploring the relationship between export and hydrodynamic processes.
		Besides the production and export of organic carbon from the euphotic zone, the fact of organic matter in the whole water column is studied.
		These heterotrophic processes can both retain ingested carbon in the water column and accelerate the downward flux of carbon by the evaluation of their impact on the carbon export from the photic zone is one of the main objectives of the project.
	www.pangaea.de /Projects/JGOFS/Canada/home/scope/GlfStLar/text.htm (1077 words)

	OSL-The Carbon Cycle
		This illuminated surface layer is called the euphotic zone, and all of the ocean's primary production occurs there.
		The depth of the euphotic zone is variable, depending on ambient conditions and the amount of particles suspended in the seawater; its lower limit corresponds to the depth where 1% of the surface light remains.
		In the Gulf of St. Lawrence, the euphotic zone usually includes the top 20 to 30 meters of water.
	www.osl.gc.ca /en/ecosystemes/flux-carbone/fig_2/euphotique.html (113 words)

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