H2o and Fine Sediment Circulation

T.J. Andersen , Grand. Pejrup , in Treatise on Estuarine and Coastal Scientific discipline, 2011

ii.fourteen.2.three.2 Effect of filter feeders on boundary layer and bed shear stress

Filter-feeding macrofauna will by and large change the bed roughness and boundary layer just because the animals themselves introduce an actress roughness element. This effect was quantified for a mussel bed with M. edulis by van Duren et al. (2006), who constitute a subtract in bed shear stress when the mussels were inactive (non feeding). This decrease was partly offset when the mussels were actively feeding due to their exhalent jets. These jets volition increase the production of turbulent kinetic energy (TKE) and bed shear stress, only van Duren et al. (2006) constitute that this consequence just induced a significant increase in bed shear stress for relatively depression-menstruation velocities.

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Food Capture, Energy Costs of

Jerry V. Mead , in Encyclopedia of Energy, 2004

5.ane.two Filter-Feeding Mussels

Filter feeding using energy to pump water into and out of clams and mussels can likewise be a very profitable feeding strategy. To examine this, the basal metabolic rate of mussels can exist estimated in the laboratory during a time when they are non feeding. Small plastic beads are and so added to an aquarium container containing mussels; the mussels starting time to filter out the particles, increasing their oxygen consumption. Real food particles added to the bedchamber in place of plastic chaplet permit measurement of growth rate and food consumption. The quantity of food energy consumed per unit of measurement free energy invested in feeding is then calculated past difference. The highest free energy render in investment into feeding is estimated at about 500% ( Table Ii).

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Microplastics in Marine Food Webs

Outi Setälä Maiju Lehtiniemi Rachel Coppock Matthew Cole , in Microplastic Contamination in Aquatic Environments, 2018

11.4.1 Filter Feeding

Filter-feeding organisms are prevalent throughout marine food webs, from small planktonic invertebrates and benthic taxa to megafauna, where they feed on suspended organic material, such every bit algae, zooplankton, fish larvae, and detritus. The size range of particles that can be ingested by a grazer depends on the feeding manner (e.g., filter feeding or raptorial), gape size, and specific feeding mechanisms of the grazer/predator. For filter feeders, the actual size limits for the ingested prey are prepare by the structure and office of the filtering appliance used for trapping particles from the suspension ( Riisgård and Larsen, 2010). Filtering devices in pause-feeding organisms are non simple sieves that mechanically clean the h2o from suspended particles. The structures of filtering appliance found in unicellular, invertebrate, or vertebrate organisms differ greatly, both between and among taxa, with varying levels of adaptability and sensory adequacy. Particle capture depends on particle type (e.g., shape, size, and density), particle concentration, h2o viscosity, the quantity of water that is filtered, and filtering efficiency. Besides direct contact, the capturing mechanisms may also involve other factors, such as chemo- and mechanoreception (Riisgård and Larsen, 2010). Moreover, experimentally measured clearance rates of plankton accept been found to vary also depending on temperature, salinity, and the type of casualty that has been offered (e.yard., Kiørboe et al., 1982; Garrido et al., 2013). Daily clearance rates of marine invertebrates tin vary from microliters (unicellular organisms, like ciliates) to milliliters (copepods), liters (bivalves), hundreds of liters (gelled zooplankton), or more (baleen whales).

Two parameters are commonly used to estimate the efficiency and outcome of filter feeding: ingestion and clearance rate. The ingestion rate denotes the number of prey particles ingested per predator in a time unit. Ingestion rate tin exist experimentally estimated direct, through observations of ingested prey particles inside the organism, or indirectly, as the disappearance of prey from the experimental media over fourth dimension. In the past, inert plastic particles (spheres) accept been used as surrogates for natural prey to guess feeding parameters in planktonic organisms (Huntley et al., 1983; Borsheim, 1984; Nygaard et al., 1988). These historical studies with Calanus and related copepod genera have demonstrated a preference for algae over polystyrene beads, alongside size selectivity (Fernandez, 1979; Donaghay and Modest, 1979; Huntley et al., 1983). All the same, observations for such preferences do not necessarily hold for all developmental stages, which further complicates things, that is, when exposure studies are existence conducted. Clearance charge per unit is a derivative of ingestion charge per unit and is calculated by dividing the latter by prey concentration. The clearance rate thus measures the water book that an individual organism can clear of nutrient particles in a time unit of measurement. To sympathise the probability of any suspended particle to be ingested by a filter-feeding organism, both the clearance rate and the concentration of suitable prey should exist taken into account.

From the viewpoint of a small filter-feeding organism under natural conditions, microplastic concentrations may be too low for routinely encountering a plastic particle. Withal, in waters containing high concentrations of microplastics, the situation is dissimilar fifty-fifty for a pocket-sized organism with a relatively low clearance rate and efficiency, such every bit a copepod. Equally an example, the experimentally defined daily clearance rates of common copepods may vary between ~   10 and <   200   mL (Frost, 1975; Engström et al., 2000; Setälä et al., 2009). In theory, a copepod feeding, for example, with a high clearance rate of 144   mL/solar day (Frost, 1975), at a concentration of 9200 plastics per m3 as has been observed from the Pacific Ocean (Desforges et al., 2014), a single microplastic would be ingested by every 0.vii copepods, assuming all particles are edible and the animals are solely undertaking passive ingestion without rejection of plastic. Assessments based on animals collected from the field have besides confirmed the function of zooplankton as entry points for microplastics to food webs. The study of Desforges et al. (2015) which was based on the analysis of the number of ingested microplastics from subsurface-nerveless zooplankton and the overall distribution of these species from the Northeast Pacific Ocean, identified run across of microplastics past zooplankton as 1 particle per every 34 copepods and 1 particle per every 17 euphausiid. The authors further estimated that both the juvenile salmon and adult returning fish would be affected daily with ingested microplastics through their zooplankton prey.

Invertebrates with a chapters for filtering larger quantities of h2o and with a longer life span (east.g., bivalves) or large filter feeders (such equally whales) may encounter microplastics far more oft than zooplankton. Bivalves are one of the cardinal organisms when entry points of microplastics to marine nutrient webs are assessed. They are efficient suspension-feeding animals that class links betwixt the pelagic and benthic ecosystems and are a central source of prey for many marine fish, birds, and mammals. In the Baltic Bounding main, it has been assessed that inside 1 year, the blue mussel beds would, in theory, filter a water volume equivalent to the whole body of water basin (Kautsky and Kautsky, 2000). The numbers of microplastics found in bivalves vary significantly ranging from <   0.five particles (Eastern Atlantic and Baltic Sea) to over 100 particles (Western Atlantic) per animal (Mathalon and Colina, 2014; Vandermeersch et al., 2015; Railo, 2017). Exposure of large filter feeders to microplastics has been shown by Fossi et al. (2014) after examining concentrations of phthalates and organochlorine compounds of a basking shark and a baleen whale. The authors concluded that microlitter is ingested by these large filter feeders together with their neustonic prey. A comparative study carried out in ii semienclosed basins, the Mediterranean Sea and the Sea of Cortez in the Gulf of California (Fossi et al., 2016), gives supporting information indicating that fin whales in highly polluted areas are exposed to major health hazards due to microplastics and their cocontaminants. Considering the vast amounts of water these animals filter (5893   m3  mean solar day−   one; Fossi et al., 2014), this conclusion is more than relevant (Box 11.three).

Box eleven.iii

Microplastics, an Result of Size

"Microplastic" is typically used to describe plastic particles smaller than 5   mm in diameter, with a lower size limit of 100   nm; plastics larger than 5   mm are considered "macroplastics," while plastics smaller than 100   nm in size are termed "nanoplastic" (Cole et al., 2011). Using these size classifications, the largest microplastic particles (5000   μm) accept a diameter l,000 times larger than the smallest microplastic (0.1   μm). Moreover, when nosotros consider volume and surface area, these differences become fifty-fifty more credible. Imagine a spherical shaped microplastic particle, like the ones used in experimental studies, or the plastic microbeads commonly used in exfoliating personal care products: a 5   mm-diameter bead is 1.25   ×   xfourteen times greater in book and 2.50   ×   ten9 larger by surface area than a 100   nm-diameter bead. Of course, most of the weathered microplastic particles that are found in the marine environment are not uniform in shape, with fibrous, planar, and irregularly shaped plastic existence most prevalent. Notwithstanding, differences in a particle's dimensions volition have a significant touch on the risk they pose to marine life. For example, microplastics of different sizes may differ in their behavior under marine conditions (i.e., buoyancy), biological availability, and capacity to incite biological furnishings. Furthermore, the larger surface-area-to-book ratios associated with smaller particles greatly increment the plastic's capacity for adsorbing (and potentially desorbing) waterborne pollutants (east.k., persistent organic pollutants and hydrophobic organic contaminants) (Koelmans et al., 2016), up to i meg times greater than that found in the surrounding seawater (Mato et al., 2001).

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Microplastic in Aquatic Environments

Messika Revel , ... Catherine Mouneyrac , in Ecotoxicology, 2019

5.2.5.3 Benthic organisms

Filter feeding organisms such as bivalves are a well-known bioindicator for ecology pollution and are closely studied. Depression quantities of MPs were found in bivalves' soft tissues from High german (0.36 ± 0.07 particles/g) and French/Belgian/Dutch farms (0.2 ± 0.3 particles/k) (Van Cauwenberghe et al. 2015; Van Cauwenberghe and Janssen 2014). Nonetheless, in Canada, 500 times greater quantities of MPs were measured by Mathalon and Hill (Mathalon and Colina 2014) in the same species. This indicates the dissimilar levels of contagion between the sites but could also be linked to differences between extraction methods. Another written report conducted in the oyster Crassostrea gigas found 0.47 ± 0.16 particles/k in the soft tissue with a subtract of nearly 25% after three days of depuration in clean seawater (Van Cauwenberghe and Janssen 2014). Murray et al. (Murray and Cowie 2011) studied the crustacean Nephrops norvegicus in the Clyde Sea and found plastic filaments in the stomach of 83% of the organisms sampled with no differences between males and females. In shrimp (Crangon crangon), Devriese et al. (Devriese et al. 2015) reported the presence of fibers in 63% of the organisms (0.68 ± 0.55 particles/g wet weight). Other authors observed MPs in the fecal casts of two polychaete species (Clymenella torquata and Alitta virens) and in the aforementioned proportion as those plant in sediment samples. This suggests that for polychaete, the ingestion and egestion of MPs is equivalent (Mathalon and Hill 2014). Also, Moore et al. (Moore et al. 2001) observed plastic fragments embedded into the tissues of the salp Thetys vagina.

Despite the relatively large number of studies on plastic particles distribution in the aquatic environment, petty is known about the biological impact on organisms, peculiarly in invertebrates.

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Water Quality and Sustainability

L. Sigg , in Comprehensive Water Quality and Purification, 2014

4.15.3.2.2 Metal bioavailability to filter-feeding and benthic organisms

For filter-feeding and benthic organisms, metal uptake may occur both from h2o and food (Croteau et al., 1998, 2007; Croteau and Luoma, 2008; Wang and Fisher, 1996, 1999). The relative importance of these two pathways depends on several parameters, among which the assimilation efficiency of metals from food is very important (Wang and Fisher, 1999). Absorption efficiency of several metals has been studied in organisms such as clams, copepods, and gastropods using in item stable metallic isotopes equally tracers (Croteau and Luoma, 2008; Croteau et al., 2007). Assimilation efficiency, which is defined every bit the metal quantity retained in organism as a function of metal in food, depends on chemic and biological factors. Differences among metals are observed, with usually higher absorption efficiencies for essential metals (e.g., Zn), than that for nonessential metals (due east.g., Ag). However, the assimilation of the nonessential and toxic methylmercury is generally high, probably considering of uptake equally lipophilic complexes (Wang and Fisher, 1999). Differences in assimilation efficiency amidst organisms are related to their feeding physiology. In addition, the distribution of metals in food particles, for example, in algae is also influencing the availability of metals. With respect to metal speciation, the speciation of metals in particles or algae used as food plays a major role. Thus, metal speciation in solution indirectly influences metal uptake past filter-feeding or benthic organisms, as it affects the metal distribution and metal content in the nutrient of these organisms, in improver to directly affecting the metal taken up over the water stage.

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Schooling Fish: A Multisensory Arroyo

M. Larsson , in Reference Module in Globe Systems and Environmental Sciences, 2014

The Development of Schooling

In filter-feeding ancestors, before vision and the OLS had developed, the hazard of predation would have been limited. The OLS probably evolved from a primitive system of epidermal ciliated sensory receptor cells, presumably mechanoreceptors (Baker et al., 2008; Streit, 2001), long earlier vertebrate ancestors developed vision (Parker, 2004). That development permitted detection of potential casualty, which increased the potential for cannibalism within a group of fish ( Figures 11 and 12 ). Small fish avoid joining a group with larger fish, although large fish do not avoid joining minor conspecifics (Lachlan et al., 1998). Increased quality of perception is probable to have resulted in an increased size homogeneity of fish shoals, which in turn may increase the capacity for moving in synchrony ( Effigy 13 ) (Larsson, 2012a, 2014).Thus, the need to cope with auditory masking problems associated with ISOL may have influenced the evolution of synchronized behavior. In combination with the resulting confusion of predators' OLS and ESP (Larsson, 2009, 2012b), synchronized locomotion may have been highly adaptive and the vertebrate encephalon may exist preprogrammed to develop synchronized behavior in various ecological niches, for example, birds flying in formation and surface-diving dolphins (Larsson, 2012a). Highly predictable ISOL in a species may stimulate the development of synchronized locomotion. Locomotion patterns, and consequently ISOL of nonhuman primates, are likely to be less anticipated than those of human gait, and therefore, the evolutionary switch to bipedalism may have influenced the evolution of human rhythmic and musical abilities (Larsson, 2014).

Figure 11. An capricious (hagfish-like) filter-feeding vertebrates with no or piffling adult OLS and vision. The take a chance of existence eaten by a bigger fish in such a grouping of early filter feeders was probably small.

 Reproduced from Larsson, Thou. (2012). Why practise fish schoolhouse? Current Zoology, 58, 116–128, with permission from Current Zoology.

Figure 12. The hazard of beingness eaten may contribute to similarity in size. The evolution of the OLS probably was important in the initiation of a predatory lifestyle (Baker et al., 2008; Northcutt and Gans, 1983). That may have increased the risk of being eaten by a larger fish in the shoal. The OLS would likewise accept helped small fish to notice and avert bigger fish.

 Reproduced from Larsson, M. (2012). Why do fish school? Electric current Zoology, 58, 116–128, with permission from Electric current Zoology.

Effigy 13. Due to the hazard of cannibalism, fish may accept developed an instinct to join fish of about the aforementioned size. Fish of similar size and body shape volition emit similar hydrodynamic signals (i.e., ISOL). ISOL may exist useful in JLS decisions, which may contribute to shoal homogeneity.

 Reproduced from Larsson, M. (2012). Why do fish schoolhouse? Current Zoology, 58, 116–128, with permission from Current Zoology.

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Biogeochemistry

H.C.Due west. Skinner , A.H. Jahren , in Treatise on Geochemistry, 2007

viii.04.three.5.3 Sponges

Found in all aquatic environments these filter-feeding organisms may occur on soft or on hard substrates at a multifariousness of depths. Some members are entirely organic, others form mineralized skeletons that are calcareous, found in clan with other CaCOiii biomineralizers (i.eastward., corals); and in that location are siliceous forms, the demosponges (Finks, 1970). The mineral portions form equally spicules, which are distinctive to a species, and some sponges produce secondary mineral deposits, which leads to dense and rigid structures, by and large typical of deeper water forms. Modern sponge lineages, mostly soft sponges, derive from Early Carboniferous as few of the Paleozoic families survived the Frasne/Famenene (Devonian) extinction (Reitner and Keupp, 1991, p. 5). Before sponges with rigid calcareous skeletons were rediscovered in the, 1960s (Hartman and Goreau, 1970), there had been differences of opinion on an appropriate inclusive classification to cover the unabridged range of such a diverse grouping of organisms (see discussions by van Soest, 1991; see as well Reitner and Keupp, 1991; Hartman, 1981).

The oldest heteractinid calcareous genus Eiffelia was described from the well-preserved spicules in the Burgess shale of British Columbia (Cambrian age) by Walcott (1920) (Effigy 17a). These skeletons were equanimous of iii different sizes of hexaform spicules, regularly and spherically distributed simply other tri-stellate, Y-shaped, tetra- and octaform spicule species were described. By the Pennsylvanian marked knobby calcareous overgrowths that occasionally became fused and obscured, the initial calcareous spicules in a grossly tubular class with a diverseness of substructures were described (Rigby and Webby, 1988) (Figure 17b).

Figure 17. (a) Drawing of the skeleton of a sponge, Eiffelia globosa from the Heart Cambiran Burgess shale of Canada illustrated in Walcott (1920). Three ranks of spicules are shown: the first society is unpatterned, the second is loosely stippled, while the third is dark stippled. Reproduced with kind permission of Springer Scientific discipline and Business Media from Rigby (1991, figure 2, p. 84). (b) Photomicrographs of Wewokella solida Girty, 1911 from the Pennsylvanian Deese formation, Oklahoma, 4×. Reproduced with kind permission of Springer Science and Business Media from Rigby (1991, figure 7B, p. 88). (c) SEM of a cleaned surface of a sclerosponge skeleton showing silicious needles embedded in, and protruding from, the aragonitic skeleton, 100×. Reproduced with kind permission of Springer Science and Business Media from Hartman (1981, figures 16–28, p. 488).

The carbonate spicules, initiated in the outer or dermal part of the organism, become interior in after forms of these organisms. The process of secondary mineralization leads to a diverseness of macrostructures, many centimeters in height (Rigby, 1991). Localities in the Silurian of North America and the Devonian of Australia show an explosion of such structures, but the morphological expressions are different suggesting ecological specificity. Similar structures are seen in modern localities (Rigby and Webby, 1988).

In siliceous sponges, the spicule-forming site is known as the desma. It is an organic biomolecule-defined structure located in the ectosomal regions near the surface of the growing sponge; information technology had been defined in, 1888 (Sollas, 1888). Successive layers of silica (opal) are deposited as rods that go decorated with symmetric or disproportionate distributed sidepieces. These spicules may fuse joining several mineralized desmas to produce a complex rigid skeletal mass (Hartman and Goreau, 1970; Hartman, 1981). A like process occurs in carbonate-mineralizing sponges. In the sclerosponges, a mod group, there is a species that has very sparse silica needles in a massive calcareous (aragonitic) structure (Hartman, 1981) (Figure 17c).

Studies of sponge lineages bear witness evolutionary patterns with convergent accommodation and mimicry across groups in both the calcareous and siliceous varieties. The amazing reappearance of the aforementioned basic structural elements, after a lengthy hiatus, even by the geologic timescale, and of diverse spicule morphology that enlarges and may fuse, producing rigid forms, suggests that sponges, similar many other invertebrate mineralized species, conform to exploit ecologic niches today every bit they did in remote times.

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Wetlands Ecosystems

Barbara L. Bedford , ... James P. Gibbs , in Encyclopedia of Biodiversity, 2001

Two.B. Major Groups of Wetland Animals

In terms of abundance, biomass, and species richness, macroinvertebrates are the nearly important wetland-dependent animals in freshwater wetlands. Four groups—the insects, mollusks, crustaceans, and annelids—make upwards the majority. The aquatic insects are the almost functionally and taxonomically diverse, and include forms that occur throughout all habitats (the bottom, deep waters, and shallow, vegetated areas) in most wetlands. The midges (Chironomidae, Diptera) constitute maybe the well-nigh widespread group of aquatic insects, and larval forms of midges typically represent the almost abundant macroinvertebrates in wetlands. Other ecologically important, widespread groups include the mosquitoes, dragonflies and damselflies (Odonata), mayflies (Ephemeroptera), caddisflies (Trichoptera), stoneflies (Plecoptera), craneflies (Tipulidae), and water beetles (e.grand., Corixidae, Belostomatidae, and Notonectidae). Among these groups, only the water beetles are entirely aquatic; members of other groups typically have aquatic larval stages that undergo a synchronized transformation ("hatch") into developed forms, which may alive for periods ranging from ane to 2   days (some mayflies) to weeks or months (many dragon-flies).

The mollusks include the many species of filter-feeding clams and herbivorous snails. The most widespread and common are fingernail clams. Larger clams and mussels are every bit widespread but less common, although they are sometimes abundant forth big rivers and lake fringes. Most big clams dwell on the bottom of wetlands, whereas the fingernail clams often occur in submerged vegetation. Snails as well occur in many wetlands and live upon stems, stalks, and leaves of aquatic vegetation, and graze on epiphytes

Figure 4. Frog and duckweed in freshwater marsh in upstate New York, U.s.. Photograph by Donald J. Leopold.

.

The crustaceans, like the aquatic insects, are commonly encountered throughout most freshwater wetlands. Especially common in open up-h2o and upon aquatic vegetation are isopods and amphipods. In protected open water areas, small zooplankters, including cladocerans and copepods are arable. Crayfish are common bottom-habitation crustaceans in many wetland ecosystems. The concluding major grouping of aquatic invertebrates, the annelids (mainly oligochaetes), are non particularly diverse taxonomically. However, they can be extremely arable in some wetlands, where they burrow in the wetland bottom or attach to aquatic vegetation.

Vertebrate animals stand for some other of import component of the wetland creature and include the amphibians, reptiles, fishes, birds, and mammals. The amphibians are composed of ii chief groups, the frogs and toads, and the salamanders. Most species of frogs and toads take circuitous life cycles that include an aquatic, usually herbivorous, larval phase adapted for rapid growth (the tadpole stage), and a terrestrial, carnivorous adult phase adapted for dispersal amidst wetlands. Their relative employ of wetlands versus uplands varies amid groups. For case, the major group of frogs in N America, the Ranidae, includes (a) members that may be mostly terrestrial merely render to wetlands to breed and sometimes to overwinter (e.thou., members of the leopard frog circuitous, eastward.g. Rana pipiens) and (b) other species (e.one thousand., bullfrogs, Rana catesbeiana) that are primarily aquatic and typically leave wetlands but to disperse to new areas. Amidst Due north American salamanders, all are wetland dependent except for members of the Plethodontidae, although even this family includes the Desmognathinae, a big group of stream-associated species. In salamanders, wetland dependency ranges from strictly aquatic (e.g., mudpuppies [Necturus], hellbenders [Cryptobranchus], Conger eels [Amphiuma], and sirens [Siren]), to semiaquatic in groups that spend much the growing season in wetlands simply overwinter on land (eastward.g., newts [Salamandridae]), to primarily terrestrial species that return to wetlands only to breed (e.g., the vernal pool-breeding mole salamanders [Ambystomidae]).

In terms of numbers, species richness, and biomass, the majority of wetland fishes are small provender fishes. In North America, the chief groups are the killifishes (Fundulus), shiners (Notropis), sunfishes (Lepomis), and mosquito fishes (Gambusia). In deeper-water wetlands or wetlands connected to permanent water bodies, larger, lesser-feeding species occur, such every bit Ictalurid catfish (e.g., bullheads) and bother (Cyprinus carpio), equally well every bit carnivorous species such as pickerel (Esox), perch (Perca), and bass (Micropterus, Morone).

Turtles are the near diverse group of wetland reptiles. Near turtles are highly aquatic and leave water simply to lay their eggs and to disperse to new habitats. Commonly encountered, highly aquatic turtles in North America include the snapping turtle (Chelydra serpentina), mud and musk turtles (Kinosternidae), and softshells (Trionychidae). The Family unit Emydidae includes many other highly aquatic turtles, such as cooters, sliders, painted turtles (Pseudemys and Chrysemys), map turtles and sawbacks (Graptemys), and terrapins (Malaclemys), also as other partially aquatic species that travel regularly among disjunct wetlands (e.one thousand., spotted turtle [Clemmys guttata]) or that use wetlands simply for hibernation (e.g., wood turtles [Clemmys insculpta]). Other wetland-dependent reptiles include the water snakes (e.g., Nerodia) that utilize wetlands primarily for feeding on fish, frogs, and crayfish, and residual above water on hydrophytes or on land at other times. Most wetland-dependent snakes are viviparous, that is, comport live young, and therefore do not undertake migrations to terrestrial habitats to lay eggs, as do turtles. Many other snakes, even so, and some lizards, live primarily in uplands but feed opportunistically in wetlands (e.g., king snakes [Lampropeltis], rat snakes [Elaphe], and garter snakes [Thamnophis]).

Several large groups of birds occur near exclusively in wetlands. These include many carnivorous (mainly fish-eating) species, such as the loons (Gaviidae), herons and bitterns (Ardeidae), several waterfowl species (Anatidae), the kingfishers (Alcedinidae), terns (Sternidae), and several raptors (Accipitridae, due east.g., ospreys Pandion haliaetus]). Omnivorous groups include the grebes (Podicipedidae), many species of diving and dabbling

Figure v. Foraging assemblage of cherry ibis and bluff ibis in the seasonally flooded grasslands of central Venezuela (Apure state). Photograph by Mark Gregory.

ducks (Anatidae), cranes (Gruidae), rails (Rallidae), and gulls (Laridae). Primarily insectivorous species include the shorebirds (Charadriidae) and many songbirds. Unlike other wetland inhabitants, birds are highly mobile and often use disjunct wetlands seasonally or fifty-fifty daily.

The final group of wetland-associated vertebrate animals, the mammals, include few, wholly wetland-dependent species. Most prominent are rodents such as the muskrat (Ondatra zibethicus) and beaver (Brush canadensis). Other obligate wetland mammals include several primitive, cannibal shrews ("water shrews" in the genus Sorex), some lagamorphs such as the swamp rabbit (Sylvilagus aquaticus) and marsh rabbit (S. palustris), and mustelids such as the river otter (Lutra canadensis). Wetlands are a critical resource, withal, for many otherwise terrestrial species, which utilize wetlands for feeding and comprehend, such as moose (Alces alces), raccoon (Procyon lotor), and mink (Mustela vison).

Animal communities of saltwater wetlands can differ substantially from those in freshwater systems considering of the furnishings of salinity on animal metabolism. More often than not speaking, analogous taxa occur in freshwater and saltwater wetlands, such that similar niches are occupied, but species richness of animals generally declines along a freshwater-brackish-saltwater gradient. Reptiles from the Gulf of Mexico region provide an example: nigh 24 species occur in fresh marsh, 16 in brackish marshes, but just 4 in table salt marshes. Of the common salt marsh species, few are table salt marsh specialists. Some terrapins are largely restricted to table salt marsh habitats, but other regularly encountered salt marsh inhabitants, such as cooters and alligators, actually adopt freshwater situations. Amphibians show a particularly sharp trend along the wetland salinity gradient. Owing to their highly permeable skins and inability to counteract the drying conditions produced past high osmotic pressures of salt h2o, very few species tin can survive in saline wetlands and even then occur only infrequently (eastward.grand., some toads).

Relatively few breeding birds specialize on salt marsh habitats, although sparrows and rails are well represented. However, table salt marshes are noted for their importance as stopover sites for the vast populations of migrating species that breed in freshwater wetlands that freeze in winter. Waterfowl, shorebirds, songbirds, and owls tin occur in brackish and common salt marsh habitats in large numbers during the colder months resulting in very diverse, if unstable, assemblages during the winter flow. Thus, though occupied for relatively brusk periods, and not by a large number of breeding species, coastal marshes however are a critical habitat in the annual cycle of many bird species.

Mammal communities in saltwater wetlands are generally quite species poor. However, the occasional effects of high densities of aquatic rodents (eastward.grand., muskrats and nutria) can exist of ecological significance. As in freshwater systems, these species tin radically alter the wetland environs through so-called "eat-outs" of the vegetation. Otherwise, saline wetlands are infrequently visited by species more than dependent on freshwater wetlands, such as otter, mink, or raccoon.

Overlap of freshwater and marine species, in conjunction with resident species that can tolerate the substantial fluctuations in salinity, produces highly complex, species-rich assemblages of fish and crustacean species in saltwater wetlands. Though characteristically species rich, these assemblages are temporally quite unstable considering of daily tidal cycles, with freshwater-associated species descending into salt marsh systems on approachable tides and marine species arriving on incoming tides. In particular, many marine fishes and crustaceans, especially shrimp, use salt marshes as plant nursery areas, particularly for post-larval and juvenile forms. Here they have reward of the lower numbers of predators in salt marshes relative to the open up ocean and take access to the high productivity of common salt marshes.

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Biogeochemistry

H.C.West. Skinner , H. Ehrlich , in Treatise on Geochemistry (2nd Edition), 2014

10.4.iii.five.3 Sponges

Found in all aquatic environments, these filter-feeding organisms may occur on soft or on hard substrates at a variety of depths. Some members are entirely organic, others grade mineralized skeletons that are calcareous, constitute in association with other CaCO3 biomineralizers, that is, corals, and in that location are siliceous forms, the demosponges (Finks, 1970). However, some representatives of drinking glass sponges (Hexactinellida) are examples of multiphase biomineralization with two different biomineral phases within their structures. The hierarchically structured glass sponge Caulophacus sp. uses the first known example of silica and calcite biocomposite to join the spicules of its skeleton together (Ehrlich et al. (2010a,b,c)) In the stalk and body skeleton of this poorly known deep-sea glass sponge, siliceous spicules are modified to form a spinose region. Spinose regions on side by side spicules are so joined past siliceous cross-links leading to unusually strong cross-spicule linkages. Information technology is at present clear from this commencement record of a biomineral other than silica that hexactinellid sponges are capable of synthesizing calcite, the bequeathed skeletal materials. It was suggested that while the low concentration of calcium in deep-sea water drove the evolution of silica skeletons, the brittleness of silica has led to the retention of the most resilient mineral, calcite, in very depression concentrations at skeletal joints (Ehrlich et al., 2011). The mineral portions form as spicules, which are distinctive to a species, and some sponges produce secondary mineral deposits, which leads to dense and rigid structures, generally typical of deeper-h2o forms. Modern sponge lineages, by and large soft sponges, derive from early Carboniferous as few of the Paleozoic families survived the Frasne/Famenene (Devonian) extinction (Reitner and Keupp, 1991, p. v). Before sponges with rigid calcareous skeletons were rediscovered in the 1960s (Hartman and Goreau, 1970), there had been differences of opinion on an appropriate inclusive classification to embrace the entire range of such a diverse grouping of organisms (meet discussions by Van Soest (1991); run across also Reitner and Keupp (1991) and Hartman (1981)).

The oldest heteractinid calcareous genus Eiffelia was described from the well-preserved spicules in the Burgess Shale of British Columbia (Cambrian age) by Walcott (1920) ( Figure 17(a) ). These skeletons were composed of three dissimilar sizes of hexaform spicules, regularly and spherically distributed, simply other tristellate, Y-shaped, tetra- and octaform spicule species were described. By the Pennsylvanian marked knobby calcareous overgrowths that occasionally became fused and obscured, the initial calcareous spicules in a grossly tubular form with a variety of substructures were described (Rigby and Webby, 1988; Figure 17(b) ).

Figure 17. (a) Drawing of the skeleton of a sponge Eiffelia globosa from the middle Cambrian Burgess shale of Canada illustrated in (Walcott, 1920). Three ranks of spicules are shown: the beginning society is unpatterned, the 2d is loosely stippled, while the third is night stippled (Rigby, 1991, Figure 2 , p. 84). (b) Photomicrographs of Wewokella solida Girty 1911 from the Pennsylvanian Deese formation, Oklahoma, ×   four (Rigby and Webby, 1988, Figure 7(b), p. 88). (c) SEM of a cleaned surface of a sclerosponge skeleton showing siliceous needles embedded in, and protruding from, the aragonitic skeleton, ×   100 (Hartman, 1981, Figures 16–28, p. 488).

The carbonate spicules, initiated in the outer or dermal part of the organism, go interior in later forms of these organisms. The procedure of secondary mineralization leads to a variety of macrostructures, many centimeters in height (Rigby, 1991). Localities in the Silurian of Northward America and the Devonian of Commonwealth of australia bear witness an explosion of such structures, but the morphological expressions are different, suggesting ecological specificity. Similar structures are seen in modernistic localities (Rigby and Webby, 1988).

In siliceous sponges, the spicule-forming site is known equally the desma. An organic biomolecule divers structure located in the ectosomal regions near the surface of the growing sponge; it had been divers in 1888 (Sollas, 1888). Successive layers of silica (opal) are deposited as rods that become decorated with symmetric or asymmetric distributed sidepieces. These spicules may fuse joining several mineralized desmas to produce a complex rigid skeletal mass (Hartman, 1981; Hartman and Goreau, 1970). A similar process occurs in carbonate-mineralizing sponges. In the sclerosponges, a modern group, there is a species that has very thin silica needles in a massive calcareous (aragonitic) construction (Hartman, 1981; Effigy 17(c) ).

Studies of sponge lineages bear witness evolutionary patterns with convergent adaptation and mimicry across groups in both the calcareous and siliceous varieties. The amazing reappearance of the same bones structural elements, after a lengthy hiatus, even past the geologic timescale, and of diverse spicule morphology that enlarges and may fuse, producing rigid forms, suggests that sponges, like many other invertebrate mineralized species, arrange to exploit ecologic niches today as they did in remote times.

About 75% of extant sponge species use dissolved silicon (DSi) to build a siliceous skeleton. Interestingly, maximum uptake efficiency occurs at experimental DSi concentrations 2 orders of magnitude higher than those in sponge habitats and is unachievable in the coastal waters of mod oceans (Maldonado et al., 2011). Such by uptake performance appears to exist rooted in a former condition at higher DSi values characteristic of pre-Tertiary (virtually 65   Mya) habitats where this sponge lineage diversified. Persistence of ancestral uptake systems causes sponges to be outcompeted by the more efficient uptake of diatoms at low ambient DSi levels that narrate contempo oceans. Thus, sublittoral sponges consume substantial coastal DSi (0.01–0.ninety   mmol   Si   thou−   two day−   1) at the expense of the primary production circuit (Maldonado et al., 2011).

Of the intriguing topics with renewed attention is the study of biomineral formation on organic templates in sponge biomineralization. Mod views (Ehrlich et al., 2011) are focusing on ii unlike mechanisms: enzymatic (silicatein-based (Cha et al., 1999; Muller et al., 2007) and nonenzymatic or self-assembling (chitin- and collagen-based) (Ehrlich et al., 2010a,b,c). Because chitin plays a critical role too in biosilicification in fungi, it had been hypothesized that chitin molecules were part of a very old organic template system involved in the biosilicification phenomenon established earlier the showtime metazoan (i.e., glass sponges) (Ehrlich et al., 2007). Lately, interest has arisen in collagen as part of the newly discovered highly hydroxylated collagen isolated from the meter-long spicules in the Hyalonema sieboldi, a glass sponge basal species. It was suggested that in addition to silicatein-based biosilicification of sponge spicules, collagen has a central role to play in the formation of the long, flexible optically pure anchoring spicules in hexacinellids. Increased atmospheric oxygen during the Proterozoic may have been of import in the posttranslational hydroxylation of proline and lysine amino acid residues, leading to silica and hydroxylated collagen-based composites for skeletal structures of the first metazoans, a coevolutionary event. Reconstruction of the evolution of biocalcification and biosilicification with respect to collagen may exist primal in showing the ancestral programs of biomineralization based on a common template. The bioconstruction of the uniquely large siliceous structures (10 orders of magnitude larger than the spicules of demosponges) may have been enabled by incorporation of collagen that played a role equally a template and as well provided structural support. Information technology means we need to rethink the role of collagen in the development of biomineralization (Ehrlich et al., 2010a,b,c ).

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Management Instance Report: Tampa Bay, Florida☆

1000. Morrison , ... K.1000. Yates , in Reference Module in Globe Systems and Environmental Sciences, 2014

Estuarine habitat targets

Because the watershed'south indigenous fish, wildlife and other living resources were presumably adapted to the proportional mix of habitat types that were historically present in the region, and because that mix has been altered by differential reductions in certain habitat types during the evolution process, ane direction strategy that has been adopted by the partnership is to 'restore the celebrated remainder' of different habitat types (Lewis and Robison, 1995; TBNEP, 1996). Nether this approach, habitat types that accept experienced the greatest reductions in surface area are given the highest priorities for restoration, with the goal of restoring the proportional mix (rather than the total acreage) of habitats to 1 that more closely resembles an earlier, less-impacted condition (Lewis and Robison, 1995).

A full of 38 species (ranging from filter feeding zooplankton species to manatees) were identified as potential indicators. Ten faunal 'guilds' (defined operationally using a combination of trophic guilds and taxonomic groups) were identified, in which the potential indicator species (depending on life stage) could be grouped:

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Open water filter feeders

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Shallow water forage fish;

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Recreational/commercial finfish and shellfish;

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Subtidal invertebrates;

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Intertidal invertebrates;

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Estuarine mollusks;

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Estuarine-dependent birds;

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Estuarine-dependent birds requiring freshwater forage areas;

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Estuarine reptiles; and

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Marine mammals

Based on the habitat requirements of each of these groups, the following half dozen habitat types were identified as important for supporting the full suite:

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Open estuarine h2o

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Oligohaline marsh

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Mangrove/Spartina

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Salt barrens

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Littoral freshwater wetlands (including ephemeral 'frogponds')

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Littoral uplands.

Every bit office of the initial target-setting process, the celebrated spatial extent of each of three estuarine habitat types (salt arid, mangrove/saltmarsh, and oligohaline Juncus marsh) were estimated using aeriform photographs from the 1938–50 catamenia. Updated areal estimates for each of these habitat types were similarly constructed, using aerial photographs taken in 1995.

Comparison between the 1950 and 1995 time periods indicated that, although a total of virtually 21% of the total acreage of these three habitat types had been lost, oligohaline habitat acreage loss was approximately 37% while salt barrens loss was 35% of the 1950 acreage. Marsh and mangrove acreage loss was well-nigh 13%. Recently updated estimates indicated that small increases in all 3 habitat types have occurred since 1995 (Robison et al., 2010) ( Table 6 ).

Table 6. Comparison of the spatial extent (area and per centum) of selected emergent estuarine habitat types over ii time periods (1950 to 1990 and 1995 to 2007)

Habitat blazon 1950–xc (Comparison) 1995–2007 (Comparison)
Low-salinity Marsh −   993 hectares +   21 hectares
−   37% +   1.2%
Polyhaline Mangrove/Marsh −   829 hectares +   153 hectares
−   12.ix% +   ii.6%
Common salt Barren −   196 hectares +   1 hectare
−   35.3% +   0.4%
Totals −   2019 hectares +   175 hectares
−   20.9% +   2.2%

Source: From Robison, D., Krebs, A., and Fouts, J. (2010). Tampa Bay Estuary Program Habitat Masterplan update. Technical Publication #06-09 of the Tampa Bay Estuary Program. 368 p.

In order to encounter the conceptual goal of 'restoring the balance' of historical habitat types, the management partnership adopted an approach that entails protecting all remaining low-salinity tidal marsh habitat and creating a minimum of 40.five hectares (100 acres) of depression-salinity marsh every five years, for a total increment over time of near 775 hectares (Robison et al., 2010; TBEP, 2006). Boosted targets include protecting and enhancing the bay's polyhaline mangrove and common salt marsh communities (which currently full about eighteen   800 hectares) and restoring (over time) about 350 hectares of salt arid habitat (TBEP, 2006). The partnership is also working to protect existing oyster bar (20 hectares) and littoral flatwoods marsh (11   000 hectares) habitats.

Cicchetti and Greening (2011) used the Tampa Bay estuarine habitat 'restore the balance' approach to develop metrics to draw estuarine ecological integrity at various spatial scales. They practical these metrics between 1900 and 2008 at the scales of the biotope (defined equally an area that is relatively uniform in physical structure and that can be identified by a dominant biota), zone (east.g., intertidal), and estuary. Results showed that all high-value biotopes lost area from 1900 to 1990. Between 1990 and 2008 however, considerable areas of seagrass, mangrove/table salt marsh, and oligohaline marsh habitat were recovered through protection and restoration activities. Over 160 hectares of salt barren habitat were lost between 1990 and 1995, after which a renewed prioritization of this habitat for protection and restoration has resulted in regained surface area. Of all habitats considered, the mangrove/common salt marsh habitat complex has lost the smallest pct of its original surface area.

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