Layers of the pelagic zone
The abyssal zone is the deepest layer of the pelagic zone that contains the very deep benthic communities near the bottom of the oceans . "Abyss" comes from the Greek word meaning "bottomless sea". At depths of 4,000 to 6,000 meters (13,123 to 19,685 feet), this zone remains in perpetual darkness and never receives daylight. It is the deeper part of the midnight zone which starts in the bathyalpelagic waters above. The abyssal zone mostly has temperatures of 2 -3 °C,as the deep waters are largely formed in cold sub polar seas
Its permanent inhabitants (for example, the Black swallower , tripod fish , deep-sea anglerfish and the giant squid ) are able to withstand the immense pressures of the ocean depths, up to 76 megapascals (11,000 psi ). Many creatures living at these depths have under-slung jaws to sift through the sand to catch food. Many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column . The pressure difference can be very significant amounting to approximately one atmosphere for each 10 meters of water depth.
Because light does not penetrate very deep in ocean-water, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column which settles down to the depths. This dead and decaying matter sustains the benthic food chain where most organisms in the deep benthic zone are scavengers or detritivores .
The area below the Abyssal Zone is the sparsely inhabited Hadal Zone which comprise the deep trenches or fissures that plunge down thousands of feet below the deep ocean floor. Examples are the many midoceanic trenches such as the Mariana Trench in the Pacific , which are almost unexplored. Only the bathyscaph Trieste and the remote control submarine Kaiko have been able to descend to these depths. Aside from being totally dark, these regions are also characterized by continuous cold and lack of nutrients.
The zone above the Abyssal Zone is the Bathyal Zone which like the previous two also belongs to the deep-sea realm. Above on the continental platform at depths less than 200 m, there are respectively the Circumlittoral, Infralittoral, Mediolittoral and Supralittoral Zones.
Marine Habitat Descriptions
Mangroves (generally) are trees and shrubs that grow in saline (or brackish) coastal habitats in the tropics and subtropics . The word is used in at least three senses:
- most broadly to refer to the habitat and entire plant assemblage or mangal, for which the terms mangrove swamp and mangrove forest are also used;
- to refer to all trees and large shrubs in the mangal, and:
- Narrowly to refer to the mangrove family of plants, the Rhizophoraceae , or even more specifically just to mangrove trees of the genus Rhizophora . Mangals are principally found in depositional coastal environments where fine sediments, often with high organic content, collect in areas protected from high energy wave action.
A lagoon is a body of comparatively shallow salt or brackish water separated from the deeper sea by a shallow or exposed sandbank , coral reef , or similar feature. Thus, the enclosed body of water behind a barrier reef or barrier islands , or enclosed by an atoll reef is called a lagoon. This application of lagoon in English dates from 1769.
Mudflats (also tidal flats, tide flats, etc.) are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons , and estuaries . Mudflats may be viewed geologically as exposed layers of bay mud , resulting from deposition of estuarine silts , clays and marine animal detritus . Most of the sediment within a mudflat is within the intertidal zone , and thus the flat is submerged and exposed approximately twice daily.
Mudflats are typically important regions for wildlife, supporting large populations, although levels of biodiversity are not particularly high. They are often of particular importance to migratory birds . In the United Kingdom mudflats have been classified as a Biodiversity Action Plan priority habitat.
The maintenance of mudflats is important in preventing coastal erosion. However, mudflats worldwide are under threat from predicted sea level rises , land claims for development, dredging for to shipping purposes, and chemical pollution . Due to the low tidal range in the Dutch Caribbean, and generally steep shores, mud flats are not a very pronounced or extensive habitat type.
In coastal environments, the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged. It always includes the intertidal zone and is often used to mean the same as the intertidal zone. However, the meaning of "littoral zone" may extend well beyond the intertidal zone to include shallow submerged areas as well as beach habitat. Due to the low tidal range in the Dutch Caribbean, and generally steep shores, the intertidal zone is generally narrow and not amounting to much more than half a meter wide.
Benthos refers to the organisms which live on, in, or near the seabed , also known as the benthic zone . They live in or near marine bottom environments, from tidal pools along the foreshore , out to the continental shelf , and then down to the abyssal depths . They can be either sedentary or mobile.
The term benthos comes from the Greek word for "depths of the sea". Benthos is also used in freshwater biology to refer to organisms at the bottom of freshwater bodies of water , such as lakes, rivers, and streams.
Sea grasses (or sea-grasses) are flowering plants from one of four plant families ( Posidoniaceae , Zosteraceae , Hydrocharitaceae , or Cymodoceaceae ), which grow under water in the marine environment.
These unusual marine flowering plants are called sea grasses not only because the leaves are long and narrow and often green, but also because the plants usually grow in large " meadows " which look like grasslands. In other words many of the species of sea grasses superficially resemble terrestrial grasses .
Because these plants need light for photosynthesis, they are limited to the photic zone (area where light reaches) , and mostly occur in shallow and sheltered coastal waters, anchored in sand or mud bottoms. They undergo pollination while submerged and complete their entire life cycle underwater. There are about sixty species worldwide.
Sea grass beds are highly diverse and productive ecosystems , and can harbor hundreds of associated species from many different phyla , for example juvenile and adult fish, epiphytic and free-living macro algae and microalgae, mollusks , bristle worms, and nematodes . Few species were originally considered to feed directly on sea grass leaves (partly because of their low nutritional content), but scientific reviews and improved research methods have shown that sea grass herbivory is a highly important link in the food chain, with hundreds of species feeding on sea grasses worldwide. These include dugongs, manatees, fish, geese, swans, sea urchins, crabs and sea turtles.
Sea grasses are sometimes labeled as ecosystem engineers because, in essence, they partly create their own habitat . By slowing down water-currents the leaves increase sedimentation , all the while the sea grass roots and rhizomes stabilize the seabed. Their importance for associated species is mainly due to their provision of shelter (through their three-dimensional structure in the water column), and for their extraordinarily high rate of primary production . As a result, sea grasses provide coastal zones with a number of ecosystem resources, for instance fishing grounds , wave protection , oxygen production, and protection against coastal erosion . Seagrass beds are a very important habitat for the Dutch Caribbean islands.
Species of this genus of algae may grow to a length of several meters; they are generally brown or dark green in color and consist of a holdfast , a stipe , and a frond. Oogonia and antheridia occur in conceptacles embedded in receptacles on special branches. Some species have berrylike gas-filled bladders which help keep the fronds afloat to promote photosynthesis . Many have a rough sticky texture, which together with a robust but flexible body helps them to withstand strong water currents. The thick masses of Sargassum provide an environment for a distinctive and specialized group of marine animals and plants, many of which are not found elsewhere.
Sargassum is also commonly found in the beach drift near Sargassum beds where they are also known as Gulfweed.
Sargassum species are found throughout tropical areas of the world and are often the most obvious macrophyte in near-shore areas where Sargassum beds often occur near coral reefs . The plants grow sub tidally and attach to coral, rocks or shells in moderately exposed or sheltered rocky or pebble areas. In some cases (e.g., the Sargasso Sea ) there are floating populations of Sargassum.Sargassum fields are especially important at depths up to 15 meters on wave-exposed shores where sea grasses have no sediments in which to root and too much water movement to allow significant coral growth .
Coral skeletons are composed of a form of calcium carbonate known as aragonite . Aragonite is one of the two common, naturally occurring forms of calcium carbonate ( Ca C O 3 ) produced by living organisms. In most reefs, the key organisms are colonial cnidarians (such as corals) that secrete an exoskeleton of calcium carbonate . The accumulation of this skeletal material, broken and piled up by wave action and bioeroders , produces massive calcareous formations that make ideal habitats for living corals and a great variety of other animal and plant life.
The epipelagic zone extends from the surface of the ocean down to depths of around 200 m (656 ft). This zone essentially corresponds to the illuminated surface zone where there is enough light and mixing for photosynthesis . Due to this, plants and animals are largely concentrated in this zone. Nearly all primary production in the ocean occurs here. This layer is the domain of fish such as tuna , many sharks , dolphins and jellyfish . This zone is also known as the “surface zone”.
From 200 m down to around 1,000 m (3,280 ft), is referred to as the mesopelagic zone.
Although some light penetrates this deep, it is insufficient for photosynthesis. The name stems from the Greek word μέσον , which means middle. At about 500 m the water becomes generally depleted of oxygen. Still, an abundance of life is able to thrive, thanks to more efficient gills or minimal movement. Animals found here include swordfish , squids , wolf fish , a few species of cuttlefish , and many other semi-deep-sea creatures.
The bathypelagic zone extends from 1,000 m down to around 4,000 m (13,123 ft).
At these depths the ocean is almost entirely dark save for the occasional bioluminescent organism, such as lantern fish . There are no living plants, and most animals survive by consuming the rain of detritus falling from the zones above, or like the marine hatchet fish , by preying upon others. Giant squid , as well as smaller squids & Dumbo octopods , are common at these depths, deep-diving sperm whales hunt . The mane stems from the Greek word βαθύς (bathýs), which means deep.
The zone from 4,000 m down to above the ocean floor is named the abyssopelagic zone.
This zone is dark and cold. The name of this zone is derived from the Greek word ἄ βυσσος (ábyssos), or abyss , which translates as “bottomless”, a holdover from the times when the deep ocean was believed to be bottomless. Very little is known about this zone. Many organisms live in hydrothermal vents in this (and other) zones.
This name refers to the deep water found in ocean trenches.
The name is derived from the Greek word Ἁ ΐδης (Haidēs), or Hades , the classical Greek underworld. This zone is mostly totally unknown, and very few species are known to live here due to oxygen depletion. Some define the hadopelagic as waters below 6,000 m (19,685 ft), whether in a trench or not.
The bathypelagic, abyssopelagic, and hadopelagic zones are very similar in character, and some marine biologists combine them into a single zone, or consider the latter two to be the same.
Basalt is a common extrusive volcanic rock . It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of the earth. It may be porphyritic containing larger crystals in a fine matrix , vesicular , or frothy scoria . Un-weathered basalt is black or grey.
Basalts (diabase) are the oldest rocks of the islands. On Curaçao they form a pile of up to 5,000 m thickness, which is known as The Curaçao Lava Formation. The Curacao Lava Formation are submarine extruded lavas which date from the Middle to Late Cretaceous (100 – 85 million year ago).
A large mass of intrusive igneous rock believed to have solidified deep within the earth.
Limestone is also a very common rock type on the Leeward Dutch islands. It is an accretionary rock composed largely of the mineral calcite ( calcium carbonate : CaCO3). The deposition of limestone strata is often a by-product and is an indicator of biological activity in the geologic record.
Caves can occupy a large area, such as the Caves of Hato in Curaçao (4900 m 2).
Most caves are often shallow and only a few meters high.
On the Lower Windward Islands the aridity meant that throughout the plantation era dams were built to collect and retain water for agricultural purposes and to recharge the ground water. Today, more that 2000 dams still exist in various states of neglect. This process happened as follow:
- By constructing series of small earth contour dams, in short distance of each other, so a uniform penetration of the rain over a large area was obtained.
- By construction in gullies of isolated heavy earthen dams, which locally hold large quantities of rainwater, the water remained on the surface sometimes for months behind the dam. These dams have a heavy stone core around which a body of weathered “diabaas” ground is built. They are fitted with an overflow (Sakadó).
- In some plantations there are still small stone dams which have a slope (Kustis) and a crown (Kopi) made of brick stone. Often in the course of time, the reservoirs behind the dams were closed with mud. The speed of the water during and after every intensive rain shower, through the gullies in the direction of the sea, was slowed down by this cross dams. The infiltration of rainwater into the soil is promoted - to supplement the ground water - and a surface water reservoir for livestock created.
Tests have shown that after rainy periods the groundwater level behind the dam increased. On Aruba where these dams are called “tanki”, the infiltration capacity of the soil is much lower than on Curaçao, mainly by evaporation, so the effect on groundwater levels is low. Behind the, retreating water, a moist area is created in which is a good climate for trees and other crops.
Obsolete name for basalt: a lava rock common on Aruba, Bonaire and Curaçao.
Old name for the complex in Aruba for the depth crystallized magmatic rocks of tona Old name for the complex in Aruba for the depth crystallized magmatic rocks of tonaliet composition.liet composition.
Is a Mountain (sub-alpine) cloud forest, which consist of areas of primary forest and represents climax vegetation. On Saba the forest on the top of Mount Scenery is called “Elfin forest” because of its high altitude mist and mossy appearance.
An escarpment is a transition zone between different physic-geographic provinces that involves a sharp, steep elevation differential, characterized by a cliff or steep slope. Most commonly, an escarpment is a transition from one series of sedimentary rocks to another series of a different age and composition.
For example the four limestone terraces on the north side of Curaçao.
A n intermittent shallow lake and wetlands, formed from the damming of a stream that drains the surrounding low hills. An example is the fresh water lagoon at Muizenberg (64 ha) in the northern suburbs of Willemstad.
Ground water is water located beneath the ground surface in pore spaces and in the fractures of litho logic formations. In caves the calcareous ground water appeared sometimes on the surface.
On the islands ground water is pumped for irrigation of gardens, courtyards and agriculture use. In some places the ground water, however, is brackish and cannot be used.
A gully is a landform created by running water . On the islands two kinds of Gullies are known; artificial gullies to transport surplus rainwater (in the rainy season) and natural gullies ones which eroded sharply into the soil the by water flow “Rooi” .
A hill is a landform that extends above the surrounding terrain, in a limited area.
Branch of agriculture concerned with the cultivation of garden plants — generally fruits, vegetables and flowers.
(Papiamentu: Hòfi) irrigated land under a cultivable farm, permanently covered with fruit trees and in particular it occupied part of an often stony plantation always thrifty agricultural land. The courtyards are notable oases in the landscape as they remain green throughout the year.
1. Coastal courtyards (St. Joris, Sta. Cruz, and Knip) are at the mouth of a large clearing system.
2. Valley Soil courtyards are just upstream from the coast courtyards.
3. Limestone courtyards are on the higher limestone plateaus.
Rural Also near the city of any land on which such trees are called to 'court' indicated.
Karst water is water which runs underground in limestone formations (the karsts) through caves and aquifers and then emerges from springs into streams and lakes.
This geological formation covers 6.9% of the island of Curaçao. Several features of the Knip formation are similar to those of the Curaçao Lava Formation and the Midden Curaçao Formation in that the soils are non-calcareous. According to beers et al. 1997), one soil, and two main “land types” can be distinguished on the basis of land form:. These are “Soils of the plains”, “Hilly land” and “Valley land”.
The Soils of the plains occupy the foot plains along the western coast. They have a shallow profile (< 45 cm) of silt loam or clay loam over weathered parent material. The very high hills dominate the north-western part of the island, the Christoffelberg being the highest. The hills are more rocky, sharp and jagged than the Curaçao Lava hills.
The profile characteristics of the Hilly land of the Knip formation are similar to those of the Hilly lands of the Curaçao Lava formation. However, the difference in the nature of the rocks of the Knip Formation is revealed by surface erosion and vegetation. The Valley land is only found near Knip on the western coast. It has a very shallow profile (<25 m) with a cherty clay loam texture. The relief is nearly level with an arroyo on the valley bottom.
Limestone is a sedimentary rock composed largely of the mineral calcite ( calcium carbonate : CaCO3). The deposition of limestone strata is often a by-product and indicator of biological activity in the geologic record.
Limestone formations, which are permeated with caves, sinkholes, and springs, are known as karsts.
Occurs mainly on the island of St. Eustatius, especially in the tuff of the Quill volcano.
A part of a town) consisting mainly of houses
A rocky shore is an intertidal area on seacoasts where solid rock predominates. Rocky shores are biologically rich environments, and make the ideal natural laboratory for studying intertidal ecology and other biological processes.
These are flat areas near the coast or in bays, sometimes under water in the rainy season. The name is also used for some bays itself. The Saliña are separated of the open sea by a stony shoreline.
Especially in the south-western part of Bonaire various Saliñas are in use. From 1972 salt is exploited, by the International Salt Company, by evaporating seawater in salt pans.
A shallow body of water, separated from the sea by sandbars or coral reefs.
(Antillean-Dutch to Papiamento Roi). Stream bed only during and shortly after rainy periods it carries water. In the Lower Windward Island these “Rois” are mainly dry.
Several “Rois”, especially on Curaçao, are near the mouth on the coast separated from the sea to increase the groundwater level or reservoirs for rainwater. At these places there is horticulture possible.
Scrubland is a plant community characterized by scrub vegetation . Scrubland consists of shrubs , mixed with grasses , herbs , and geophytes. Scrublands may either occur naturally or be the result of human activity. They may be the mature vegetation type in a particular region and remain stable over time, or a transitional community that occurs temporarily as the result of a disturbance, such as fire. A stable state may be maintained by regular natural disturbance such as fire or browsing . Scrubland may be unsuitable for human habitation because of the danger of fire.
A spring is a point where groundwater flows out from the ground. An example is the Spring of San Pedro on Curaçao.
On Saba near Ladder Point (south west- Saba) there is a warm water spring.
Those ecosystems dominated by man-made structures. Included in this category are cities, towns, villages, strip developments along highways, transportation, power, and communications facilities, and areas such as those occupied by mills, shopping centers, industrial and commercial complexes, and institutions that may, in some instances, be isolated from urban areas.
The Washikemba formation constitute the oldest rocks on the island Bonaire. They are also volcanic in origin, like those on Aruba and Curaçao. Washikemba Formation contains alkynes, lava's, tuff and intrusive bodies but also, unlike in Curaçao, vulcanite richer in silica acid: porphyry and porphyry tuff.
Ecologically, woodland is an area covered in trees, usually at low density, forming an open habitat, allowing sunlight to penetrate between the trees, and limiting shade. Woodland may support an understory of shrubs and herbaceous plants including grasses .