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35-435: Hydrachnidia , also known as " water mites ", Hydrachnidiae , Hydracarina or Hydrachnellae , are among the most abundant and diverse groups of benthic arthropods, composed of 6,000 described species from 57 families. As water mites of Africa , Asia , and South America have not been well-studied, the numbers are likely to be far greater. Other taxa of parasitengone mites include species with semi-aquatic habits, but only

70-495: A decrease in benthic macroinvertebrate biomass, which lead to the disappearance of food sources into the substrate. Because the benthic system regulates energy in aquatic ecosystems, studies have been made of the mechanisms of the benthic zone in order to better understand the ecosystem. Benthic diatoms have been used by the European Union's Water Framework Directive (WFD) to establish ecological quality ratios that determined

105-1209: A region, as well as prevalence and intensity of host infection, are impacted by a multitude of environmental and biological factors, and have shown great geographic variation. In some cases, high infection intensities have significantly increased chances of host mortality and reduced fecundity . Water mite larvae have been considered as a potential biological control agents, although low natural infection intensities warrant supplementation with other control strategies in order to be effective. Some water mites continue to be parasites in their post-larval stages. These are mainly associated with molluscs, such as mussels ( Najadicola ingens and many species of Unionicola ) and snails (two species of Dockovdia ). That said, not all associations with other animals are parasitic; some Unionicola species merely use other animals as safe, well-oxygenated places to lay eggs and to pass their resting stages (protonymph, deutonymph). The majority of water mites found parasitic on mosquitoes belong to two genera: Parathyas ( Hydryphantidae ) and Arrenurus ( Arrenuridae ). The biology and ecology of these specific host-mite interactions have been well studied, likely due to

140-802: A symbiotic relationship with each other. In the deep sea, which covers 90–95% of the ocean floor, 90% of the total biomass is made up of prokaryotes. To release all the nutrients locked inside these microbes to the environment, viruses are important in making it available to other organisms. Modern seafloor mapping technologies have revealed linkages between seafloor geomorphology and benthic habitats, in which suites of benthic communities are associated with specific geomorphic settings. Examples include cold-water coral communities associated with seamounts and submarine canyons, kelp forests associated with inner shelf rocky reefs and rockfish associated with rocky escarpments on continental slopes. In oceanic environments, benthic habitats can also be zoned by depth. From

175-420: Is called the abyssal plain and is usually about 4,000 metres (13,000 ft) deep. The ocean floor is not all flat but has submarine ridges and deep ocean trenches known as the hadal zone . For comparison, the pelagic zone is the descriptive term for the ecological region above the benthos, including the water column up to the surface. At the other end of the spectrum, benthos of the deep ocean includes

210-466: Is not easy to map or observe these organisms and their habitats, and most modern observations are made using remotely operated underwater vehicles (ROVs), and rarely submarines . Benthic macroinvertebrates have many important ecological functions, such as regulating the flow of materials and energy in river ecosystems through their food web linkages. Because of this correlation between flow of energy and nutrients, benthic macroinvertebrates have

245-655: Is recommended in the European Union benthic monitoring program (by Kelly 1998 for the United Kingdom then in the EU and for the EU as a whole by CEN 2003 and CEN 2004) and in some United States programs (by Moulton et al. 2002). Benthic gross primary production (GPP) may be important in maintaining biodiversity hotspots in littoral zones in large lake ecosystems . However, the relative contributions of benthic habitats within specific ecosystems are poorly explored and more research

280-480: Is the zone bordering the shore; light penetrates easily and aquatic plants thrive. The pelagic zone represents the broad mass of water, down as far as the depth to which no light penetrates. Benthos are the organisms that live in the benthic zone, and are different from those elsewhere in the water column ; even within the benthic zone variations in such factors as light penetration, temperature and salinity give rise to distinct differences, delineated vertically, in

315-678: The Karoo Supergroup in South Africa, dating to the Wordian stage of the Middle Permian, approximately 266 million years ago. Benthic zone The benthic region of the ocean begins at the shore line ( intertidal or littoral zone ) and extends downward along the surface of the continental shelf out to sea. Thus, the region incorporates a great variety of physical conditions differing in: depth, light penetration and pressure. Depending on

350-547: The lemon shark . Because light does not penetrate very deep into ocean-water, the energy source for the benthic ecosystem is often marine snow . Marine snow is organic matter from higher up in the water column that drifts down to the depths. This dead and decaying matter sustains the benthic food chain ; most organisms in the benthic zone are scavengers or detritivores . Some microorganisms use chemosynthesis to produce biomass . Benthic organisms can be divided into two categories based on whether they make their home on

385-607: The prosoma rather than being set on the surface of the cuticle . The group has two synapomorphies , features inherited from a common ancestor. In larvae, the genu of the palp has two setae . In post-larval stages, there are complex dermal structures consisting of a gland paired with a sensory seta (glandularia), possibly for defense against predators. The palps of post-larval water mites vary depending on their diet. The egg-eating Hydryphantidae, Hydrodromidae, and Hydrachnidae have chelate (pincer-like) palps. The crustacean-eating Arrenurus (Arrenuruidae) have uncate palps to grasp

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420-600: The Hydracarina are properly subaquatic. Water mites follow the general Parasitengona life cycle: active larva, inactive (calyptostasic) protonymph, active deutonymph, inactive tritonymph and active adult. Usually, larvae are parasites, while deutonymphs and adults are predators. Water mites may be brilliant red or orange in colour, unusual among freshwater invertebrates, but they also display more subtle blues, greens and yellows. They are also unusual among mites in some lineages having movable, internalized eye lenses sunk deep within

455-517: The ability to influence food resources on fish and other organisms in aquatic ecosystems . For example, the addition of a moderate amount of nutrients to a river over the course of several years resulted in increases in invertebrate richness, abundance, and biomass . These in turn resulted in increased food resources for native species of fish with insignificant alteration of the macroinvertebrate community structure and trophic pathways. The presence of macroinvertebrates such as Amphipoda also affect

490-407: The benthos, and the degree of benthic-pelagic coupling. The benthos in a shallow region will have more available food than the benthos in the deep sea. Because of their reliance on it, microbes may become spatially dependent on detritus in the benthic zone. The microbes found in the benthic zone, specifically dinoflagellates and foraminifera , colonize quite rapidly on detritus matter while forming

525-413: The bottom levels of the oceanic abyssal zone . For information on animals that live in the deeper areas of the oceans see aphotic zone . Generally, these include life forms that tolerate cool temperatures and low oxygen levels, but this depends on the depth of the water. As with oceans, the benthic zone is the floor of the lake, composed of accumulated sunken organic matter . The littoral zone

560-457: The dominance of certain types of algae in Benthic ecosystems as well. In addition, because benthic zones are influenced by the flow of dead organic material , there have been studies conducted on the relationship between stream and river water flows and the resulting effects on the benthic zone. Low flow events show a restriction in nutrient transport from benthic substrates to food webs, and caused

595-649: The ecological status of lakes in the UK. Beginning research is being made on benthic assemblages to see if they can be used as indicators of healthy aquatic ecosystems. Benthic assemblages in urbanized coastal regions are not functionally equivalent to benthic assemblages in untouched regions. Ecologists are attempting to understand the relationship between heterogeneity and maintaining biodiversity in aquatic ecosystems. Benthic algae has been used as an inherently good subject for studying short term changes and community responses to heterogeneous conditions in streams. Understanding

630-479: The eggs, larvae and pupae of aquatic insects, and non-arthropod invertebrates such as rotifers , nematodes , and oligochaetes . The egg-eating water mites often prey on the eggs of the same insects they parasitise as larvae. To feed, water mites bite prey, inject saliva containing digestive enzymes to liquefy the tissue, and suck out the liquid. The oldest known water mites are from the Onder Karoo locality within

665-430: The fecundity of Coquillettidia perturbans females by approximately 3.5 eggs per additional mite. Even though Arrenurus mite larvae have been considered as potential biocontrol agents, unrealistic numbers would need to be released in order to prove effective on their own. Nymphs and adults of water mites are predatory. They prey on other water mites, small crustaceans (e.g. cladocerans , ostracods and copepods ),

700-435: The groups of organisms supported. Many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column: the pressure difference can be very significant (approximately one atmosphere for each 10 meters of water depth). Many have adapted to live on the substrate (bottom). In their habitats they can be considered as dominant creatures, but they are often a source of prey for Carcharhinidae such as

735-492: The margins of temporary ponds, springs, streams, and seepage areas in North America and Europe. Nymphs and adults can be seen crawling and mating along substrate beginning in early Spring, soon after the recession of surface ice. Eggs are laid soon after the thaw, and larvae typically emerge and begin host seeking within 30–40 days. According to Mullen (1977), P. barbigera attach exclusively to female mosquitoes as they land near

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770-442: The number of eggs laid by gravid An. crucians by nearly 100%. High mite loads also significantly decreased the fecundity of field-collected An. crucians , but to a lesser extent than those infected in the lab. Similar consequences of high Arrenurus mite infection intensities were observed in other host-mite relationships. For example, Smith and McIver (1984) found that Arrenurus danbyensis loads of greater than 5 mites decreased

805-411: The ocean floor or a few centimeters into the ocean floor. Those living on the surface of the ocean floor are known as epifauna . Those who live burrowed into the ocean floor are known as infauna . Extremophiles, including piezophiles , which thrive in high pressures, may also live there. An example of benthos organism is Chorismus antarcticus . Sources of food for benthic communities can derive from

840-490: The only water mite life stage to have parasitic relationships with other organisms. Upon location of a host, larvae pierce host integument with their chelicerae and feed on hemolymph until fully engorged or brushed off. Common host groups include insects with aquatic or semi-aquatic juvenile stages, including, but not limited to, the Diptera (true flies), Odonata (dragonflies and damselflies), and Trichoptera (caddisflies). It

875-471: The potential mechanisms involving benthic periphyton and the effects on heterogeneity within a stream may provide a better understanding of the structure and function of stream ecosystems. Periphyton populations suffer from high natural spatial variability while difficult accessibility simultaneously limits the practicable number of samples that can be taken. Targeting periphyton locations which are known to provide reliable samples – especially hard surfaces –

910-402: The potential to significantly impact the health of their host. In laboratory settings, the survival of Anopheles crucians mosquitoes parasitized by Arrenurus (Meg.) pseudotenuicollis was found to decrease from 23.32 to 6.25 days between those harboring the least and greatest numbers of attached mites respectively. Under similar conditions, infection intensities equalling 17-32 mites decreased

945-664: The shallowest to the deepest are: the epipelagic (less than 200 meters), the mesopelagic (200–1,000 meters), the bathyal (1,000–4,000 meters), the abyssal (4,000–6,000 meters) and the deepest, the hadal (below 6,000 meters). The lower zones are in deep, pressurized areas of the ocean. Human impacts have occurred at all ocean depths, but are most significant on shallow continental shelf and slope habitats. Many benthic organisms have retained their historic evolutionary characteristics. Some organisms are significantly larger than their relatives living in shallower zones, largely because of higher oxygen concentration in deep water. It

980-507: The significant relevance of mosquitoes to human health. Parathyas barbigera are among the most common mite species found parasitizing mosquitoes, especially those of the genera Aedes and Ochlerotatus . Their host range is likely much wider, as studies have detected P. barbigera parasitizing other dipteran families, such as Tipulidae (crane flies), Ptychopteridae (phantom crane flies), Chloropidae (grass flies), and Empididae (dagger flies). These mites are typically abundant along

1015-464: The slim appendages of crustaceans. Most other water mite families have linear palps for grappling with prey animals. Hydrachnidia are ubiquitous in nearly all freshwater habitats of every continent except Antarctica . Typical habitats include streams and marshes , but they may also be found in more obscure areas such as treeholes , hot springs , deep lakes and waterfalls . Some species have also adapted to marine environments. Larvae are usually

1050-565: The upper water column in search of hosts. Once an immature host is located, Arrenurus larvae loosely bind to their integument, and monitor them until the adult emerges. Host muscle contractions just prior to emergence stimulate mite larvae to move towards the ecdysial opening and attach to the host along intersegmental sutures on their thorax and abdomen. Differences in preferred attachment site between mite species appear to be related to differences in host emergence behavior. Full larval engorgement takes approximately three days, during which they have

1085-404: The water column above these habitats in the form of aggregations of detritus , inorganic matter, and living organisms. These aggregations are commonly referred to as marine snow , and are important for the deposition of organic matter, and bacterial communities. The amount of material sinking to the ocean floor can average 307,000 aggregates per m per day. This amount will vary on the depth of

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1120-416: The water's edge to oviposit, which was supported by an extensive field study in which he observed zero mite larvae on 15,000 Aedes pupae, and dissection of parasitized females revealed them all to be parous. Mullen hypothesized that this life history strategy increased chances of mite survival two-fold because those parasitizing males would likely die before returning to a suitable adult habitat. No literature

1155-415: The water-body, the benthic zone may include areas that are only a few inches below the surface. The continental shelf is a gently sloping benthic region that extends away from the land mass. At the continental shelf edge, usually about 200 metres (660 ft) deep, the gradient greatly increases and is known as the continental slope. The continental slope drops down to the deep sea floor. The deep-sea floor

1190-461: Was found discussing the impact of P. barbigera on mosquito physiology and survival. Larval mites of the genus Arrenurus are also common ectoparasites of many mosquito species. In contrast to P. barbigera , Arrenurus mites are fully aquatic and prefer permanent habitats, such as swamps and marshes. Females lay eggs in protected areas hidden among the abundant vegetation of these habitats, and upon hatching, larvae can be found swimming throughout

1225-445: Was originally believed that water mite larvae located hosts by accidental contact, but recent studies have found they likely utilize a combination of visual, tactile, and chemical cues. Even though larvae are capable of sensing the presence of a nearby host, it has been suggested that they are unable to distinguish between host species, and rather select hosts solely based on spatial and temporal coincidence. The abundance of water mites in

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