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But why is there only just this one single genus of insect living on the open oceans? Retrieved Technical Diving in the Deepest Lake on Earth. Further, natural deposition of sediments to form intertidal flats and emergent wetlands can occur over relatively short time spans in deltas and estuaries, depending on such factors as hydraulic conditions and sediment loads. Strategies and techniques for marine conservation tend to combine theoretical disciplines, such as population biology, with practical conservation strategies, such as setting up protected areas, as with marine protected areas MPAs or Voluntary Marine Conservation Areas. Similarly, halfway technologies work to increase the population of marine organisms.
About 9, species mostly bugs and beetles have all stages under or on water. In about 30, species only the larval stage is aquatic flies, mosquitos. Insects are found throughout the world except near the poles and, with but a single exception, pervade every habitat except the sea.
Some are found at depths of 1, meters in Lake Baikal, some are to be found only in rain-filled tree holes, while others inhabit caves and underground aquifiers. Freshwater habitats are the only aquatic habitats where insects dominate. In saltwater and brackish habitats, crustacea the next most numerous arthropod dominate. Despite their low numbers compared to the terrestrial insects, marine insects still have a tremendous impact on man.
Flies are the most numerous and economically important species of marine insects. The disease-bearing mosquitoes, biting horse flies, deer flies, and midges have impeded the human development of enormous areas of coastal land. And other marine flies can transmit diseases such as Leishmaniasis.
Unlike the dominating land-based insects, however, the marine insects have additional problems to overcome in their fight for survival. For example, how do aquatic insects avoid drowning? Most insects that land on water are trapped by the water surface tension and tiny ones can even drown inside a water droplet, unable to break out of the bubble surface. Many are covered with a water-repellent waxy layer. There is very little oxygen in water as low as 0.
Water contains less oxygen the warmer it is. This is why there is often more life in a cool pond shaded by trees and in temperate climates. So, to extract oxygen from water, an animal will have to process a lot of water to get the same amount of oxygen. That is probably one reason why adult aquatic insects continue to breathe air instead of developing gills. Usually only aquatic insect larvae develop gills to absorb oxygen from the water.
So, how do aquatic insects obtain their oxygen? Like mosquito larva and water scorpion, they can snorkel with a breathing tube. The end of the tube usually has bristles to break the water surface tension and keep the tube open. Others have a scuba tank.
A skin of air that is trapped by hairs on the body or under the wing covers Water Beetle. The insect breathes the air in the bubble through the holes in its abdomen spiracles just like other insects. Living on the margin of water and air, many aquatic insects have developed ingenious ways to sense the world and to move around. Most aquatic insects are sensitive to water ripples to detect predators or prey. Many also create ripples to find mates and communicate with each other Whirligig Beetle, Pond Skater.
In a double-vision adaptation the Whirligig Beetle has eyes divided horizontally to see both under and above water. This is very useful when predators can attack you from both below and above. Many paddle underwater with oar-like legs. These legs are long, flattened and fringed. The hairy fringes spread out on the power stroke increasing the surface area, and bend in on the return stroke to reduce water resistance.
Water Beetle, Water Boatman. These insects usually have flattened streamlined bodies or are torpedo-shaped. The Camphor Beetle Stenus also skates on the water surface but has a neat trick to enhance its speed. When alarmed, it releases a chemical from its back legs that reduces the water surface tension.
In this way, the water surface tension on the front pulls it forwards. It shoots forwards on its front feet which are held out like skis, and steers itself by flexing its abdomen. This tiny beetle is the size of a rice grain but can travel nearly 1m a second this way. As we have seen above, marine insects have developed succesful strategies for survival in an aqueous environment.
Sea skaters feed primarily on zooplankton trapped at the sea surface, grasping their prey with their short front legs and sucking them dry. They have never been observed breaking the water surface to feed—i. While members of the coastal species deposit their eggs on fixed materials such as mangrove tree trunks or rocks, open-ocean species lay eggs on just about anything that floats, including empty seashells, wood, feathers, seeds and even lumps of tar.
Among the most interesting aspects of the Halobates is how they manage to walk or skate across the surface of the ocean. The surface tension of the air-sea interface allows them to stand or move on the water at a speed as fast as one meter per second. As long as the surface tension is maintained, sea skaters are able to move normally. If the surface tension is lowered by pollutants or detergents, they flop on the surface and eventually sink.
Tiny hook-shaped hairs, about 1. These trap a layer of air surrounding the insect, making them buoyant. Thus, they are basically enclosed in an air bubble; if they are pushed under the water, they quickly pop up again.
If sea skaters are caught in rough seas and trapped beneath the surface for short periods, this jacket of air provides them with enough oxygen to survive. No other animal on Earth lives in such a vast two-dimensisional habitat. They are the only marine invertebrates constrained to traveling, feeding and reproducing only at the surface of the ocean. Among the dificulties of living in such a vast world is how the Halobates find each other to breed and lay eggs.
But why is there only just this one single genus of insect living on the open oceans? The five known species of Halobates are distributed around the world roughly between latitudes degrees north or south of the equator. Do Halobates require these warm waters, or are they more widely distributed but have not yet been detected?
Why are there so few species, and how do they live in a habitat where no other insect occurs? Only 0. This is very strange indeed. Dr Lanna Cheng, a well-known long-time expert on marine insects at the University of California, San Diego, with others, gives several hypotheses as to why this is so. The first hypothesis suggests that insects are limited by salinity.
While this may be true for the majority of insects, many flies have effecient osmoregulatory mechanisms that allow then to tolerate salinity in excess of 3 times that of the ocean.
This is true of many insects and yet chironomid fly larvae survive at depths below those that even the deepest diving mammals can reach. The third hypothesis suggests that the combination of salinity and depth imposes a further limitation of oxygen content in ocean water.
Again, certain fly larvae are able to survive months without oxygen, and numerous aquatic insects survive in polluted waters with similar or lower oxygen concentrations. Finally, a fourth hypothesis considers the fact that insects were successful because they colonized land.
By moving away from the ocean, they adapted to a terrestrial existence while their major competitors the crustaceans stayed in the sea and continued to adapt. As millions of years passed, insects lost their ability to successfully compete in the ocean while crustaceans have had only limited success in invading land.
Dr Lanna Cheng believes that this is the most likely explanation for the abscence of insects in the oceans. As potential evidence, it is noted that the only insects that live on the open ocean, live on its surface.
As such, they never come in contact with the crustaceans living beneath its surface. There are many questions still unanswered about this strange case of the Halobates. How come that they alone of the so many insects managed to adapt to life on the oceans?
Whatever hypothesis is true, though, if any of them are, the Halobates are a really remarkable example of marine life rarely, if ever, to be observed by divers. New Foundland, Canada. Raja Ampat, Indonesia. Marine Insects - walking on water. Glowing Jellyfish. Diving rebreathers, what is it like? Ireland's Connemara. A visit to Cressi-Sub. Technical Matters: Tables vs Computers. Sylvia Earle. Yolanda Wreck - where did she go? Alex Mustard. Skip to main content.
Marine Insects. Read so far. Similar losses affect other regions as well, although on a less grand scale than in coastal Louisiana. Coastal zone Coastal waters and adjacent shorelands which are strongly influenced by each other and uses of which have a direct and significant impact on coastal waters. Creation Construction or formation of a habitat of a different type that existed before a site was disturbed or conversion of one habitat form to another.
The principal differences between restoration and creation are the condition and status of the habitat acreage rather than the technologies used.
Because the technology is essentially the same, creation is treated as a subset of restoration as an approach to improving marine habitat. Enhancement Improvement of one or more of the values of an existing habitat, usually one that has been degraded or disturbed. May result in a decline of other values. Improvement General result, if beneficial, of one or a combination of protection, enhancement, restoration, and creation initiatives. Marine habitat Marine and estuarine habitats and contiguous shorelines within the coastal zone.
These areas include marine wetlands such as tidal marshes, emergent wetlands, sea grass beds, kelp forests, and mangrove swamps. Also included are beaches, shallow inshore and near shore submerged environments, and tidal and intertidal flats. Offshore marine habitat is outside the boundaries of this assessment except for artificial reefs and offshore berms on the continental shelf.
Marine habitat management A comprehensive approach to stewardship of marine habitat including protection, enhancement, restoration, creation, and administration. Mitigation Measures taken to reduce adverse impacts. A regulatory approach that, in effect, permits conversion of habitat in return for compensation in the form of enhancement, restoration, or creation of other habitat.
Monitoring The collection of data to aid project planning and design and to enable evaluation of project performance. Partial restoration Return of a degraded or altered natural area as close as possible to its condition prior to disturbance if full restoration is not feasible Box Protection Use of structural and nonstructural means, including regulation, to minimize or prevent harm to existing habitats. Restoration Return of a degraded or altered natural area or ecosystem to a close approximation of its condition prior to disturbance Box River delta, intense development of shorelines and inland areas, and use and diversion of fresh water within the watershed are causing or contributing to hypersalinity subsidence and erosion problems Bay Institute of San Francisco, ; EPA, ; Josselyn and Buchholz, ; McCreary et al.
Along much of the Atlantic and Gulf Coasts, engineered. In this report, restoration is defined as the return of a marine natural area or ecosystem to a close approximation of its condition prior to disturbance. In restoration, ecological damage to the resource is repaired. Both the structure and the functions of the natural area are improved or recreated.
Merely recreating the form without the functions, or the functions in an artificial configuration bearing little resemblance to a natural resource, does not constitute restoration. The goal is to emulate a natural, functioning, self-regulating system that is integrated with the ecological landscape in which it occurs.
In practical application, since ecosystems are the cumulative result of a sequence of climatological and biological events, full ecological restoration is rarely achieved. Therefore, efforts to restore habitat may necessarily consist of various measures to enhance or partially restore natural functions depending on site-specific conditions, habitat improvement objectives, and other factors.
In some cases, the ecological landscape may have been so altered as to preclude a return to a predisturbed condition. In these cases, partial restoration may be feasible, recognizing that all natural functions may not be completely restored and that assisted regulation may be necessary, such as control of water and sediment flows.
Marine ecosystems typically involve dynamic forces including substantial physical energy in the form of currents and waves, local or global changes in relative mean sea level, and sediment streams that can lead to rapid changes in the characteristics of a natural area. Therefore, defining what constitutes a predisturbed condition can be problematic. In such cases, the characteristics of a natural, functioning, self-regulating system that is integrated into its ecological landscape and which emulates nearby undisturbed natural areas is an alternative frame reference.
Although use of dredged material does not constitute restoration, per se, restoration can be accomplished using dredged material in its native environment to achieve general parameters which will aid in natural marsh evolution in those locations where marine sediments would normally form essential substrates for intertidal and emergent wetlands habitat.
Placing marine sediments so as to mimic natural deposition of sediment at sites where conditions otherwise favor restoration would preclude the chemical changes that occur when marine sediments are exposed to air in upland areas or in wetlands above appropriate intertidal elevations. Further, natural deposition of sediments to form intertidal flats and emergent wetlands can occur over relatively short time spans in deltas and estuaries, depending on such factors as hydraulic conditions and sediment loads.
The rapid placement of suitable dredged material at appropriate locations and elevations in an estuary or delta approximates natural deposition and can be an important, but not exclusive, element of a marine habitat restoration project. Engineering technologies and structures maintain an increasingly tentative balance with nature in every coastal state. Throughout the coastal zone, habitat is continually lost to human development; what remains is under constant threat of degradation or further loss EPA, The causes of the decline in marine habitat quality and quantity may be traced to several factors.
Human activities have altered natural current action and sedimentation patterns; degraded water quality by introducing excess nutrients, toxins, and sediments into coastal waters as a result of nonpoint and point-source pollutants; altered estuarine inflow and outflow patterns; and changed other physical, chemical, and biological processes.
Protecting finfish and shellfish habitats is a concern, as are sedimentation starvation and excess sedimentation in deltaic and other fragile wetland systems. Scientific concern has also arisen regarding the effects of beach stabilization measures, whether physical structures or placement of beach-quality sands, on biotic communities for which beaches provide habitat.
Considerations include the fate of biota in the nearshore borrow area, impacts on biota using the changed shoreline, changes in sedimentation patterns and shoreline stability beyond the project boundaries, and project stability. Sweeping changes in the policies and practices of all parties involved in marine habitat protection and enhancement are needed to arrest and reverse these trends NRC, a. Institutional, political, and sociological factors that have made it difficult to strike a balance among competing objectives for the use of coastal sites include:.
Despite these constraints, engineers working in the coastal zone and using the technologies and practices they develop can contribute to better management of.
Where feasible, these capabilities can be put to use for the protection of natural marine habitats before they are degraded or lost or for after-the-fact enhancement or restoration. It is time to rethink the role of coastal engineering in serving both human and environmental objectives. An integrated, holistic approach that encompasses engineering practices and capabilities and understands the functions of marine ecosystems and their habitat is especially important.
Engineers are faced with seemingly contradictory objectives: Through research and development, education, and the innovative application of engineering knowledge, the engineering profession has the opportunity to accommodate these competing objectives.
A comprehensive understanding of engineering practices and capabilities and their relationship to the ecology of marine habitats is as important to informed decision making over habitat use as are economic considerations. A positive role for the engineering profession can be developed in cooperation with the scientific community to protect and enhance marine habitat and contribute information essential to the formation and refinement of national policy and management objectives.
Although examples of successful applied engineering capabilities to accomplish environmental objectives are numerous, traditional engineering practices have not always recognized and dealt fully with the varied needs of marine habitats. New territory for the engineering profession includes methods to protect habitats, especially from contaminants, erosion, and subsidence, while preserving or retaining their natural attributes.
An ecosystem approach to project design and implementation that recognizes the ecological interdependencies of marine systems is seldom applied.
Further development of the potential for coastal engineering to protect, enhance, restore, and create marine habitats therefore depends in part on further collaboration between the coastal sciences and engineering.
Scientists and engineers concerned with marine systems share many interests and have a wide variety of tools at their disposal. Some technology transfer has occurred, demonstrating the fact that science and engineering can be complementary. For example, marine turtles returned to historical beach nesting areas after well-timed deposition of beach-quality dredged material.
Knowledge of habitat requirements, when the turtles came ashore to nest, and the capability to place beach-quality material prior to turtle arrival were required. Applied research has demonstrated that beach nourishment can be timed to accommodate environmental, stabilization, and aesthetic objectives.
This measure is now widely used in Florida Higgins and Fisher, ; Hodgin et al.
Although there are still gaps in knowledge about turtle nesting, the approach used shows the potential benefits from cooperative application of scientific knowledge and coastal engineering technology. Fisheries biologists and navigation project design engineers interested in successful construction and maintenance of navigation channels are both concerned with hydraulic and hydrologic conditions, water quality, sedimentation patterns, salinity and temperature, and other physical and chemical factors.
Although discipline perspectives differ, each group is vitally interested in the effects of physical modifications to an existing system. For example, changes to an estuary's tidal prism that do not maintain hydraulic balance within the system can greatly affect sedimentation rates and salinity, benefiting either navigation, biota, both, or neither.
The full potential of scientific and engineering contributions to marine habitat protection, creation, restoration, and enhancement has yet to be realized despite the advances that have been made. Over the past three decades, the scientific community's understanding of marine habitats has advanced greatly.
Science produced monitoring, sampling, and analytical techniques that help detect and respond to problems affecting marine habitats. The rapid advances in the computation power of computers, computer modeling, and graphic representations has significantly advanced the capability to analyze, interpret, and apply the data that are collected.
This understanding and monitoring capabilities have been instrumental in decision making to set environmental quality objectives NRC, b,c. Science recognizes the importance of a holistic approach to understanding the interrelationships of species and how they function to consume and change the chemical composition of wastes such as sewage, buffer the system against shock, and secure the health and reproductive capacities of species forming the ecosystem.
This recognition requires an understanding of the chemical and physical. Density-dependent interactions as well as the effects of density-independent factors such as temperature, light, heat, precipitation, wave actions, and pollutants of various types, must also be understood. Understanding the geology, hydrology, and chemical characteristics such as salinity of the system enables description of physical and chemical processes that are important in determining sensitive land forms, sediment transport regimes, and the quality of sediment and water.
Understanding the formation of substrates in estuaries and the material composing them is not fully developed. Likewise, the effects of organic matter and contaminants such as pesticides in substrates as they pertain to restoration of natural functions in and performance of habitat restoration projects are not thoroughly understood and are a concern. This is an important consideration because the substrates are the foundation materials for marine habitats.
Nevertheless, the holistic approach is an integrated one that enables human activities to fortify rather than destroy fragile and complex coastal ecosystems. National concerns about the relationship of human activities and natural marine systems involve economic and social sciences, as well as natural sciences.
Assessment of economic and social values of natural marine systems is marked by controversy because of uncertainties in scientific knowledge about the functioning of marine ecosystems and the contribution of marine habitat to commercial fisheries, recreational activities, and other activities. These factors make it difficult to establish economic values of marine habitat in natural uses.
Economic sciences can be employed to assess the costs and benefits of alternate uses, residential development, for example Bell, ; Costanza and Wainger, ; Smith, The social sciences can address the range of variables and help identify interested parties whose participation in planning and implementation is needed to ensure project acceptability and success, examine social attitudes and changes, and address quality-of-life issues Caldwell, ; Davos, ; Dwivedi, ; Hickman and Cocklin, ; McCreary et al.
The disparity in the ability to quantify the value of marine habitat as a natural resource places these attributes at a disadvantage when determining their fate—whether they should be preserved and improved or converted.