Aquatic macroinvertebrates are insects in their nymph and larval stages, snails, worms, crayfish, and clams that spend at least part of their lives in water. These insects play a large role in freshwater ecosystems by recycling nutrients as well as providing food to higher trophic levels.
Aquatic macroinvertebrates are oviparous, however their life history strategies vary. Their reproductive strategies fall along a continuum between semelparous and iteroparous, and involve differences in egg number, egg size, and brood care.[3] Once they hatch, the majority of aquatic macroinvertebrates undergo three main life stages: nymph, pupa, and adult. Some taxa, like dragonflies, spend their adult stage outside the water. Other taxa, like water beetles, are aquatic for their entire lives. The evolution of different life history strategies of aquatic macroinvertebrates has allowed species to take advantage of differences in food supply and allow some to better tolerate extreme environmental conditions.[4]
Feeding
Macroinvertebrates play an important role in aquatic food webs as they are major food sources for higher trophic levels. Macroinvertebrates are also crucial in aquatic nutrient cycling.[5] They are often food generalists and have therefore been classified into five main groups called functional feeding groups. This facilitates the incorporation of their ecological roles into research studies. Their classification into these five groups is based on a combination of their morphological characteristics and behavioral mechanisms of feeding.[6] These groups include shredders, grazers, gatherers, filterers, and predators.
The River Continuum Concept proposed by Vannote,[7] predicts the functional distribution of aquatic macroinvertebrates in a stream based on food resources. This concept highlights the importance of freshwater ecosystem inputs to food resources and how this influences aquatic macroinvertebrate communities
Shredders
Shredders feed on coarse particulate organic matter (CPOM) from terrestrial leaf litter inputs. Using their mouthparts, they shred organic matter to feed and in doing so, suspend smaller particles into the water column. Examples include Diptera (e.g. Tipulidae) and Plecoptera (e.g. Tallaperla).
Grazers
Grazers use rasping mouthparts to scrape biofilm and algae off rocks and submerged aquatic vegetation and include Ephemeroptera (e.g. Baetidae). Their grazing affects algal biomass in aquatic ecosystems and therefore primary production in aquatic ecosystems.[8]
Collectors/gatherers primarily scavenge stream or lakebed substrates for deposited fine particulate organic matter (FPOM) and dead organisms. They play a role in bioturbation and resuspension of organic matter and include Diptera (e.g. Chironomidae).
Filterers
Filterers remove suspended FPOM from the water column using a variety of filtering mechanisms. They expend less energy searching for food, rather relying on sufficient current velocity and upstream food supply. Examples include Diptera (e.g. Simuliidae) and Coleoptera (e.g. Elmidae).
Predators
Predators consume animal tissue and therefore have direct top-down effects on the food web. Some predator species include Odonata and Plecoptera larvae which utilize grasping mouthparts to ambush their prey.[9]
Bioindicators
Aquatic macroinvertebrate communities are strongly influenced by their environment, and act as bioindicators for the overall condition of freshwater ecosystems.[10] Species have been classified based on their tolerance to environmental changes, and their assemblages can therefore indicate if an ecosystem is healthy. The orders Ephemeroptera, Plecoptera, and Trichoptera are sensitive to pollutants so they are used to calculate an EPT index to indicate water general quality.[11][12] Specific effects of pesticides can be indicated with the SPEAR index.[13] E.g. German stream monitoring of pesticide exposure and effects.[14]
↑ Merritt, Richard; Kenneth, Cummins (1996). An introduction to the aquatic insects of North America. Kendall Hunt.
↑ Verberk, Wilco; Siepel, Henk; Esselink, Hans (2008). "Life-history strategies in freshwater macroinvertebrates". Freshwater Biology. 53 (9): 1722–1738. doi:10.1111/j.1365-2427.2008.02035.x. hdl:2066/72066.
↑ Mandaville, S.M. (2002). Benthic macroinvertebrates in freshwaters: Taxa tolerance values, metrics, and protocols. Vol.128. Nova Scotia: Soil & Water Conservation Society of Metro Halifax.
↑ Vannote, Robin; Minshall, Wayne; Cummins, Kenneth; Cushing, Colbert (1980). "The river continuum concept". Canadian Journal of Fisheries and Aquatic Sciences. 37: 130–137. doi:10.1139/f80-017.
↑ Rosenberg, David; Vincent, Resh (1993). Freshwater Biomonitoring and Benthic Macroinvertebrates. New York, NY, USA: Springer US. p.488.
↑ Merritt, R.W.; Cummins, K.W.; Berg, M.B. (2008). An Introduction to the Aquatic Insects of North America. Kendall Hunt Pub. Co.
↑ Richardson, R.E. (1928). "The bottom fauna of the Middle Illinois River, 1913-1925". Illinois Natural History Survey Bulletin. 17 (1–12): 387–475. doi:10.21900/j.inhs.v17.291.
Mayflies are aquatic insects belonging to the order Ephemeroptera. This order is part of an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies. Over 3,000 species of mayfly are known worldwide, grouped into over 400 genera in 42 families.
Aquatic insects or water insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some diving insects, such as predatory diving beetles, can hunt for food underwater where land-living insects cannot compete.
Freshwater ecosystems are a subset of Earth's aquatic ecosystems. They include lakes, ponds, rivers, streams, springs, bogs, and wetlands. They can be contrasted with marine ecosystems, which have a larger salt content. Freshwater habitats can be classified by different factors, including temperature, light penetration, nutrients, and vegetation. There are three basic types of freshwater ecosystems: Lentic, lotic and wetlands. Freshwater ecosystems contain 41% of the world's known fish species.
A midge is any small fly, including species in several families of non-mosquito nematoceran Diptera. Midges are found on practically every land area outside permanently arid deserts and the frigid zones. Some midges, such as many Phlebotominae and Simuliidae, are vectors of various diseases. Many others play useful roles as prey for insectivores, such as various frogs and swallows. Others are important as detritivores, and form part of various nutrient cycles. The habits of midges vary greatly from species to species, though within any particular family, midges commonly have similar ecological roles.
The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the basis of the adult mouthparts. Integripalpian larvae construct a portable casing to protect themselves as they move around looking for food, while annulipalpian larvae make themselves a fixed retreat in which they remain, waiting for food to come to them. The affinities of the small third suborder Spicipalpia are unclear, and molecular analysis suggests it may not be monophyletic. Also called sedge-flies or rail-flies, the adults are small moth-like insects with two pairs of hairy membranous wings. They are closely related to the Lepidoptera which have scales on their wings; the two orders together form the superorder Amphiesmenoptera.
A bioindicator is any species or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other small water crustaceans that are present in many water bodies can be monitored for changes that may indicate a problem within their ecosystem. Bioindicators can tell us about the cumulative effects of different pollutants in the ecosystem and about how long a problem may have been present, which physical and chemical testing cannot.
The Chironomidae comprise a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae. Many species superficially resemble mosquitoes, but they lack the wing scales and elongated mouthparts of the Culicidae.
Aquatic biomonitoring is the science of inferring the ecological condition of rivers, lakes, streams, and wetlands by examining the organisms that live there. While aquatic biomonitoring is the most common form of biomonitoring, any ecosystem can be studied in this manner.
River ecosystems are flowing waters that drain the landscape, and include the biotic (living) interactions amongst plants, animals and micro-organisms, as well as abiotic (nonliving) physical and chemical interactions of its many parts. River ecosystems are part of larger watershed networks or catchments, where smaller headwater streams drain into mid-size streams, which progressively drain into larger river networks. The major zones in river ecosystems are determined by the river bed's gradient or by the velocity of the current. Faster moving turbulent water typically contains greater concentrations of dissolved oxygen, which supports greater biodiversity than the slow-moving water of pools. These distinctions form the basis for the division of rivers into upland and lowland rivers.
A riffle is a shallow landform in a flowing channel. Colloquially, it is a shallow place in a river where water flows quickly past rocks. However, in geology a riffle has specific characteristics.
Ephemerellidae are known as the spiny crawler mayflies. They are a family of the order Ephemeroptera. There are eight genera consisting of a total 90 species. They are distributed throughout North America as well as the UK. Their habitat is lotic-erosional, they are found in all sizes of flowing streams on different types of substrates where there is reduced flow. They are even found on the shores of lakes and beaches where there is wave action present. They move by swimming and clinging, they are very well camouflaged. Most species have one generation per year. They are mostly collector-gatherers.
The River Continuum Concept (RCC) is a model for classifying and describing flowing water, in addition to the classification of individual sections of waters after the occurrence of indicator organisms. The theory is based on the concept of dynamic equilibrium in which streamforms balance between physical parameters, such as width, depth, velocity, and sediment load, also taking into account biological factors. It offers an introduction to map out biological communities and also an explanation for their sequence in individual sections of water. This allows the structure of the river to be more predictable as to the biological properties of the water. The concept was first developed in 1980 by Robin L. Vannote, with fellow researchers at Stroud Water Research Center.
Chloroperlidae are a family of stoneflies, commonly known as green stoneflies, with more than 200 species and 22 genera. They appear green to yellow in colour, and are popularly used among fisherman as bait for trout fishing. Green stoneflies live in the benthic zone of the cold streams and rivers of five continents and four zoogeographical regions, emerging from the water to live in the riparian zone as adults. They are sensitive to pollutants, making them an indicator species for determining the quality of water bodies. Chloroperlidae are hemimetabolous, having no pupal stage, but instead hatch from eggs as nymphs and mature directly into adults. They are omnivorous, feeding on small organisms and plant particles, and become more carnivorous as they mature. The classification of Chloroperlidae is contested, with some believing that they should be considered as members of different orders, as opposed to the order Plecoptera that they currently belong to.
Energy, nutrients, and contaminants derived from aquatic ecosystems and transferred to terrestrial ecosystems are termed aquatic-terrestrial subsidies or, more simply, aquatic subsidies. Common examples of aquatic subsidies include organisms that move across habitat boundaries and deposit their nutrients as they decompose in terrestrial habitats or are consumed by terrestrial predators, such as spiders, lizards, birds, and bats. Aquatic insects that develop within streams and lakes before emerging as winged adults and moving to terrestrial habitats contribute to aquatic subsidies. Fish removed from aquatic ecosystems by terrestrial predators are another important example. Conversely, the flow of energy and nutrients from terrestrial ecosystems to aquatic ecosystems are considered terrestrial subsidies; both aquatic subsidies and terrestrial subsidies are types of cross-boundary subsidies. Energy and nutrients are derived from outside the ecosystem where they are ultimately consumed.
SPEARpesticides is a trait based biological indicator system for streams which quantitatively links pesticide contamination to the composition of macroinvertebrate communities. The approach uses species traits that characterize the ecological requirements posed by pesticide contamination in running waters. Therefore, it is highly specific and only slightly influenced by other environmental factors. SPEARpesticides is linked to the quality classes of the EU Water Framework Directive (WFD)
A glacier stream is a channelized area that is formed by a glacier in which liquid water accumulates and flows. Glacial streams are also commonly referred to as "glacier stream" or/and "glacial meltwater stream". The movement of the water is influenced and directed by gravity and the melting of ice. The melting of ice forms different types of glacial streams such as supraglacial, englacial, subglacial and proglacial streams. Water enters supraglacial streams that sit at the top of the glacier via filtering through snow in the accumulation zone and forming slush pools at the FIRN zone. The water accumulates on top of the glacier in supraglacial lakes and into supraglacial stream channels. The meltwater then flows through various different streams either entering inside the glacier into englacial channels or under the glacier into subglacial channels. Finally, the water leaves the glacier through proglacial streams or lakes. Proglacial streams do not only act as the terminus point but can also receive meltwater. Glacial streams can play a significant role in energy exchange and in the transport of meltwater and sediment.
DNA barcoding is an alternative method to the traditional morphological taxonomic classification, and has frequently been used to identify species of aquatic macroinvertebrates. Many are crucial indicator organisms in the bioassessment of freshwater and marine ecosystems.
Freshwater salinization is the process of salty runoff contaminating freshwater ecosystems, which can harm aquatic species in certain quantities and contaminate drinking water. It is often measured by the increased amount of dissolved minerals than what is considered usual for the area being observed. Naturally occurring salinization is referred to as primary salinization; this includes rainfall, rock weathering, seawater intrusion, and aerosol deposits. Human-induced salinization is termed as secondary salinization, with the use of de-icing road salts as the most common form of runoff. Approximately 37% of the drainage in the United States has been affected by salinization in the past century. The EPA has defined two thresholds for healthy salinity levels in freshwater ecosystems: 230 mg/L Cl− for average salinity levels and 860 mg/L Cl− for acute inputs.
Invertebrate drift is the downstream transport of invertebrate organisms in lotic freshwater systems such as rivers and streams. The term lotic comes from the Latin word lotus, meaning "washing", and is used to describe moving freshwater systems. This is in contrast with lentic coming from the Latin word lentus, meaning slow or motionless that typically describe still or standing waters such as lakes, ponds, and swamps.
Stenoperla prasina is a species of stonefly belonging to the family Eustheniidae. This species is endemic to New Zealand and is classified as "Not Threatened" under the New Zealand Threat Classification System. It is found on the North, South and Stewart Island / Rakiura Islands as well as on Little Barrier Island. Although adults of this species are most often coloured bright green, this species can be coloured yellow. This species inhabits clean, cold, running streams and rivers with stony bottoms within native bush. It is a known indicator of water quality. The larvae eat plant detritus and other aquatic insects while the adult insects feed on sooty mould fungi as well as other plant matter. The adults of this species are a known food source for New Zealand long tailed bats. Adults have been dissected and have been found to have been carrying Nematomorpha and trematode parasites. The New Zealand Department of Conservation classifies this species as "Not Threatened". In 2022 a specimen of this species was the 5 millionth specimen to be digitised in the Natural History Museum, London collection.
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