Artículos de revistas: "Macroinvertebrate grazers"

1

Jordan, J. y PS Lake. "Grazer-epilithon interactions in an Australian upland stream". Marine and Freshwater Research 47, n.º 6 (1996): 831. http://dx.doi.org/10.1071/mf9960831.

Texto completo

Resumen

Effects of macroinvertebrate grazers on the distribution of their food resource, epilithon, were examined in a south-eastern Australian stream. The hypothesis that grazers would significantly alter the development of epilithon was tested experimentally: macroinvertebrates were excluded from some experimental substrata and allowed to colonize others. Epilithic chlorophyll a concentration, organic matter content and total diatom density were used to monitor the effects of the grazer assemblage over 35 days. As predicted, epilithon density was higher on bricks with exclusion barriers than on bricks open to colonization by grazers. Similarly, diatom densities were significantly higher on bricks from the grazer-exclusion treatment. Patterns in the development of epilithon over time point to the importance of prevailing abiotic conditions in determining the outcome of macroinvertebrate grazing. Differences in total epilithon biomass, algal biomass and diatom density between treatments clearly indicate the independent importance of macroinvertebrate grazing to the microdistribution of epilithon in upland streams.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Krist, Amy y Caroline Charles. "Comparison of Grazing Impacts Between the Invasive New Zealand Mudsnail Potamopyrgus Antipidarum, and Native Macroinvertebrates". UW National Parks Service Research Station Annual Reports 31 (1 de enero de 2008): 97–107. http://dx.doi.org/10.13001/uwnpsrc.2008.3715.

Texto completo

Resumen

To understand the impacts of an herbivorous invasive species on native herbivores, it is critical to quantify the relative impact of the invasive and the native species on shared resources. In a field experiment, we compared grazing efficacy of periphyton by the invasive New Zealand mudsnail, Potamopyrgus antipidarum, and 3 native macroinvertebrate grazers. Depending on the measure of periphyton biomass, P. antipodarum removed as much or more periphyton than any of the native grazers. When we examined diatom genera individually, P. antipodarum also suppressed the relative abundance of the greatest number of diatom genera and suppressed those diatoms more than the native grazers. As a result, P. antipodarum should compete strongly for periphyton with native grazers. In particular, because Ephemerella mayflies were the second most effective grazers and grazed many diatom genera similarly to the invasive snails, these mayflies may be competing with P. antipodarum in the introduced range. Overall, grazing ability may contribute to the invasion success of P. antipodarum.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Řezníčková, Pavla, Lenka Tajmrová, Petr Pařil y Světlana Zahrádková. "Effects of drought on the composition and structure of benthic macroinvertebrate assemblages – a case study". Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 61, n.º 6 (2013): 1853–65. http://dx.doi.org/10.11118/actaun201361061853.

Texto completo

Resumen

Natural drying up of streams is not common in Central Europe. Nevertheless, the recurrent drying up of small streams in last decades has shown an urgent need to pay attention to the impact of global climate change. This strong disturbance influences conditions in streams markedly and causes changes in the taxonomical and functional structure of biota. The aim of the study was to compare aquatic macroinvertebrate assemblages of one intermittent and one permanent brook in South Moravia. The study was carried out in two stretches with otherwise comparable environmental parameters. Lower densities of macroinvertebrates were found at the intermittent site the difference was statistically significant. The number of taxa and diversity were significantly higher at the permanent site. Functional structure of the assemblages also varied. The shares of rheobionts, grazers and predators differed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Cremona, Fabien, Dolors Planas y Marc Lucotte. "Assessing the importance of macroinvertebrate trophic dead ends in the lower transfer of methylmercury in littoral food webs". Canadian Journal of Fisheries and Aquatic Sciences 65, n.º 9 (septiembre de 2008): 2043–52. http://dx.doi.org/10.1139/f08-116.

Texto completo

Resumen

Total mercury and methylmercury concentrations ([THg], [MeHg]) were measured in littoral macroinvertebrates from Lake St. Pierre, Quebec, Canada. Functional groups (detritivore, grazer, edible predator, inedible predator) explained the greatest fraction of [MeHg] variation compared with time (year, month), and space (station and shore). Greatest [THg] and [MeHg] were found in inedible predators mostly from families of heteropterans and coleopterans. Detritivores and grazers exhibited the lowest Hg concentrations, while edible predators were intermediate. Inedible predators also had the highest percentage of MeHg ([MeHg]/[THg]), with some taxa close to 100%. Such high percentages are seldom observed in freshwater organisms other than piscivorous fish. MeHg burden (concentrations × biomass) in inedible predators accounted for 10% of the MeHg pool for the whole invertebrate community. These large quantities of MeHg are sequestrated in aquatic “trophic dead ends” and could partly explain the low [MeHg] measured in fish, compared with [MeHg] of macroinvertebrates from Lake St. Pierre and other freshwater ecosystems with large littoral zones. We recommend taking into account the inedible organisms in Hg cycling models to avoid a possible overestimation of the MeHg pool available to fish.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Merten, Eric C., William D. Hintz, Anne F. Lightbody y Todd Wellnitz. "Macroinvertebrate grazers, current velocity, and bedload transport rate influence periphytic accrual in a field-scale experimental stream". Hydrobiologia 652, n.º 1 (26 de junio de 2010): 179–84. http://dx.doi.org/10.1007/s10750-010-0329-1.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Klumpp, D. W., J. S. Salita-Espinosa y M. D. Fortes. "The role of epiphytic periphyton and macroinvertebrate grazers in the trophic flux of a tropical seagrass community". Aquatic Botany 43, n.º 4 (noviembre de 1992): 327–49. http://dx.doi.org/10.1016/0304-3770(92)90046-l.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Brock, T. C. M., R. M. M. Roijackers, R. Rollon, F. Bransen y L. van der Heyden. "Effects of nutrient loading and insecticide application on the ecology of Elodea-dominated freshwater microcosms II. Responses of macrophytes, periphyton and macroinvertebrate grazers". Archiv für Hydrobiologie 134, n.º 1 (28 de junio de 1995): 53–74. http://dx.doi.org/10.1127/archiv-hydrobiol/134/1995/53.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Fournier, Robert J. y Daniel D. Magoulick. "Drought and nutrient pollution produce multiple interactive effects in stream ecosystems". PLOS ONE 17, n.º 7 (14 de julio de 2022): e0269222. http://dx.doi.org/10.1371/journal.pone.0269222.

Texto completo

Resumen

Drought and nutrient pollution can affect the dynamics of stream ecosystems in diverse ways. While the individual effects of both stressors are broadly examined in the literature, we still know relatively little about if and how these stressors interact. Here, we performed a mesocosm experiment that explores the compounded effects of seasonal drought via water withdrawals and nutrient pollution (1.0 mg/L of N and 0.1 mg/L of P) on a subset of Ozark stream community fauna and ecosystem processes. We observed biological responses to individual stressors as well as both synergistic and antagonistic stressor interactions. We found that drying negatively affected periphyton assemblages, macroinvertebrate colonization, and leaf litter decomposition in shallow habitats. However, in deep habitats, drought-based increases in fish density caused trophic cascades that released algal communities from grazing pressures; while nutrient enrichment caused bottom-up cascades that influenced periphyton variables and crayfish growth rates. Finally, the combined effects of drought and nutrient enrichment interacted antagonistically to increase survival in longear sunfish; and stressors acted synergistically on grazers causing a trophic cascade that increased periphyton variables. Because stressors can directly and indirectly impact biota—and that the same stressor pairing can act differentially on various portions of the community simultaneously—our broad understanding of individual stressors might not adequately inform our knowledge of multi-stressor systems.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Akamagwuna, Frank Chukwuzuoke, Augustine Ovie Edegbene, Phindiwe Ntloko, Francis Ofurum Arimoro, Chika Felicitas Nnadozie, Dennis Junior Choruma y Oghenekaro Nelson Odume. "Functional groups of Afrotropical EPT (Ephemeroptera, Plecoptera and Trichoptera) as bioindicators of semi-urban pollution in the Tsitsa River Catchment, Eastern Cape, South Africa". PeerJ 10 (15 de diciembre de 2022): e13970. http://dx.doi.org/10.7717/peerj.13970.

Texto completo

Resumen

We examined the distribution patterns of Ephemeroptera, Plecoptera, and Trichoptera functional feeding groups (EPT FFGs) in five streams that drain semi-urban landscapes in the Tsitsa River catchment, Eastern Cape Province of South Africa. We undertook macroinvertebrate and physicochemical analysis over four seasons between 2016 and 2017 at eight sites in three land-use categories (Sites 1, 2 and 3), representing an increasing gradient of semi-urban pollution. Five EPT FFGs (shredders, grazers/scrapers, predators, collector-gatherers and collector-filterers) were fuzzy coded and analyzed using RLQ-R (environmental characteristics of samples), L (taxa distribution across samples) and Q (species traits) and fourth-corner analyses. Physicochemical variables, including phosphate-phosphorus, total inorganic nitrogen and temperature, were the most influential variables that significantly influenced the distribution patterns of EPT FFGs in the Tsitsa River. RLQ and the fourth-corner model revealed varying responses of FFGs to semi-urban pollution. Of the five FFGs, collectors were the most abundant EPT FFGs in the study area, exhibiting disparate responses to disturbances, with collector-gatherers associated with impacted sites and significantly associated with phosphate-phosphorus. On the other hand, collector-filterers decreased with increasing semi-urban disturbance and exhibited a significant negative association with phosphate-phosphorus, total inorganic nitrogen and temperature. Overall, this study provides further insights into the environmental factors that influence the distribution patterns of FFGs in Afrotropical streams and the potential use of FFGs as indicators of anthropogenic pollution in tropical streams and rivers.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Stewart, Timothy W., Jeffrey G. Miner y Rex L. Lowe. "An experimental analysis of crayfish (Orconectes rusticus) effects on a Dreissena-dominated benthic macroinvertebrate community in western Lake Erie". Canadian Journal of Fisheries and Aquatic Sciences 55, n.º 4 (1 de abril de 1998): 1043–50. http://dx.doi.org/10.1139/f98-022.

Texto completo

Resumen

Quantitative descriptions of trophic interactions between Dreissena (zebra and quagga mussels) and other organisms are needed for an understanding of Dreissena's effects on energy flow and community dynamics in the Great Lakes. We used a field experiment to quantify effects of crayfish (Orconectes rusticus) predation on a Dreissena-dominated benthic macroinvertebrate community in western Lake Erie. Rocks colonized by Dreissena and associated macroinvertebrates were placed in cages and cageless reference plots located at a depth of 4 m. Crayfish (0, 8.3, and 20.8 individuals ·m-2) placed in cages were allowed to graze for 28 days. Dreissena had a greater effect than crayfish on the macroinvertebrate community, with positive relationships observed between Dreissena densities and both total macroinvertebrate biomass and densities of the amphipod Gammarus fasciatus. However, crayfish at densities of 20.8 individuals ·m-2 still reduced non-Dreissena macroinvertebrate biomass and Gammarus densities by 33 and 37%, respectively, relative to crayfish exclosures. Crayfish had negligible effects on Dreissena densities or shell length frequency distribution. Because crayfish and amphipods are prey for several fish species, trophic interactions among Dreissena, amphipods, and crayfish may be important in channeling energy from Dreissena to higher trophic levels in the Great Lakes.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Holomuzki, Joseph R. y Barry J. F. Biggs. "Food Limitation Affects Algivory and Grazer Performance for New Zealand Stream Macroinvertebrates". Hydrobiologia 561, n.º 1 (mayo de 2006): 83–94. http://dx.doi.org/10.1007/s10750-005-1606-2.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Let, Marek, Jan Špaček, Martin Ferenčík, Antonín Kouba y Martin Bláha. "Insecticides and Drought as a Fatal Combination for a Stream Macroinvertebrate Assemblage in a Catchment Area Exploited by Large-Scale Agriculture". Water 13, n.º 10 (13 de mayo de 2021): 1352. http://dx.doi.org/10.3390/w13101352.

Texto completo

Resumen

This case study documents responses in a headwater macroinvertebrate assemblage to insecticide pollution and hydrological drought. In 2014, the Doubravka brook (Czech Republic) was damaged by a large overflow of a mixture of chlorpyrifos (CPS) and cypermethrin (CP). In 2016–2017, this brook was then affected by severe drought that sometimes led to an almost complete absence of surface water. We found significant relationships between the strength of both these disturbances and the deeper taxonomic levels of both the overall macroinvertebrate assemblage (classes) and the arthropod assemblage alone (orders and dipteran families), as well as the functional feeding groups (FFGs). The CPS-CP contamination was mostly negatively correlated to arthropod and non-arthropod taxa and was positively correlated only with FFG collector-gatherers; on the other hand, the drought was negatively correlated to Simuliidae, Ephemeroptera, Trichoptera, and the FFG of grazer-scrapers and passive filterers. Drought conditions correlated most positively with Isopoda, Ostracoda, Heteroptera, adult Coleoptera, and predator and active filterer FFGs. The chosen eco-indicators (SPEARpesticides, SPEARrefuge, BMWP, and EPT) used as support information reveal the poor ecological status of the whole assemblage, including the control site, the cause of which is most likely to be the exploitation of the adjacent catchment area by large-scale agriculture. This type of agricultural exploitation will undoubtedly affect macroinvertebrate assemblages as a result of agrochemical and soil inputs during run-off events and will also exacerbate the effect of droughts when precipitation levels drop.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Riley, Leslie, Mark Dybdahl y Robert Hall. "Fertilization of Algal Resources By an Exotic Snail May Facilitate Invasion". UW National Parks Service Research Station Annual Reports 27 (1 de enero de 2003): 116–22. http://dx.doi.org/10.13001/uwnpsrc.2003.3555.

Texto completo

Resumen

We studied positive and negative effects of snail consumers on their resource to determine if positive consumer effects may be facilitating invasion. Consumer- resource interactions often focus on losses to the resource, even though the resource might benefit if consumers recycle nutrients. The New Zealand mudsnail, Potamopyrgus antipodarum, an exotic in western U.S. rivers, attains high densities and dominates macroinvertebrate communities. In one well-studied river, it consumes the majority of primary productivity, cycles most nitrogen and can grow faster at higher densities. In field experiments, we tested the hypothesis that this invasive grazer stimulates algal growth via nitrogen excretion, which might explain its self-facilitation and invasiveness. Using in-stream cages subdivided into "with snails" and "without snails" sections, we examined the response of periphytic algae to snail grazing and excretion and snail excretion alone at various levels of snail biomass. We found that chlorophyll a and GPP (gross primary production) decreased as the biomass of snails increased in the grazed sections. Snail excretion, in the absence of grazing, increased both chlorophyll a and GPP, demonstrating a positive effect of snails on the resource, consistent with the nutrient recycling and enrichment hypothesis. We found no evidence for increased algal growth at intermediate snail densities in grazed treatments, as predicted by the Herbivore Optimization Curve hypothesis. However, the difference in chlorophyll a between "with snails" and "without snails" treatments increased as snail biomass increased. This suggests that snail compensation of the resource, through excretion, decreases at extremely high levels of grazing pressure and the net effect of snail grazing becomes negative. Together, these results suggest that invasiveness in some rivers may be fostered by this self-facilitation and recycling of essential nutrients.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Yule, Catherine M., Luz Boyero y Richard Marchant. "Effects of sediment pollution on food webs in a tropical river (Borneo, Indonesia)". Marine and Freshwater Research 61, n.º 2 (2010): 204. http://dx.doi.org/10.1071/mf09065.

Texto completo

Resumen

The impact of pollution on the trophic ecology of the Kelian River (Borneo, Indonesia) was studied by comparing food webs (on the basis of gut analysis and field and laboratory observations) at six sites. The upper sites were in pristine rainforest but the river became increasingly polluted downstream, largely owing to sedimentation from alluvial gold mining activities. Four previous studies all showed a downstream decrease in macroinvertebrates (mean abundance: 272 per 400 cm2 at Site 1 dropped to 2.6 at Site 6; mean number of taxa: 37.6 at Site 1 down to 1.6 at Site 6), and this was highly correlated with suspended solids. Food webs also reflected the effect of pollution. Cleaner sites had more complex food webs, with more elements, links, higher linkage density and higher complexity than did downstream polluted sites, which lacked grazers, shredders and filterers. Several taxa that were grazers at clean sites became collector-gatherers at polluted sites. Despite the enormous impact of pollution, cessation of alluvial mining activities resulted in some recovery. The resilience of the fauna is likely to be enhanced by the tropical conditions with high rainfall, rapid flow rates and high temperatures, coupled with rapid life cycles. Fish distribution and diets did not appear to be affected by pollution.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Ho, Susie S., Nick R. Bond y P. Sam Lake. "Comparing food-web impacts of a native invertebrate and an invasive fish as predators in small floodplain wetlands". Marine and Freshwater Research 62, n.º 4 (2011): 372. http://dx.doi.org/10.1071/mf10222.

Texto completo

Resumen

Gambusia holbrooki is an invasive predatory poeciliid fish in wetlands of south-eastern Australia, where it coexists with the native waterbug Anisops thienemanni (Notonectidae). Gambusia has been shown to produce trophic cascades, leading to increased algal biomass following invasion, whereas these effects relative to the often-dominant invertebrate predator Anisops are unknown. Given its flexible diet, we predicted that Gambusia would feed more broadly than Anisops, thereby reducing the abundance of zooplankton grazers, and increasing chlorophyll a. We tested this hypothesis in experimental 110-L wetland mesocosms, using Gambusia and Anisops alone and in combination, in addition to no-predator treatments. We ran two experiments lasting 91 and 35 days, respectively. Both fish and macroinvertebrates generated weak trophic cascades, resulting in minor increases in chlorophyll a above concentrations in control treatments. Gambusia, in lowering total zooplankton abundances, triggered a larger, although still relatively small, algal response relative to Anisops. Impacts of both predators on dominant invertebrate grazers (e.g. Simocephalus spp., copepod nauplii) were similar, although Anisops was associated with an increase in ostracod (Newnhamia sp.) numbers. The similar trophic role of the two predators on algae was unexpected, given their different effects on planktonic communities and their very different taxonomic positions and zoogeographic origins.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Mackay, Rosemary J. "Colonization by Lotic Macroinvertebrates: A Review of Processes and Patterns". Canadian Journal of Fisheries and Aquatic Sciences 49, n.º 3 (1 de marzo de 1992): 617–28. http://dx.doi.org/10.1139/f92-071.

Texto completo

Resumen

Ways in which invertebrates colonize lotic habitats are reviewed, tracing patterns in behaviour, trophic ecology, and life history that could lead to predictions concerning resilience of stream communities after disturbance. Patterns are described for small-scale experimental studies using introduced or natural substrates, for large-scale observations of new or rewatered channels, for rivers recovering from pollution, and for unstable rivers with fluctuating discharge. Colonization depends on invertebrate mobility (drift, swimming, crawling, and flight), substrate texture and associated food supplies, competition, and predation. Epilithon-browsers and filter feeders can use the resources of smooth stones; gatherers colonize as fine detritus accumulates; grazers increase as periphyton becomes established; shredders and predators tend to be late arrivals. Propagules for colonization are made more available by asynchronous and aseasonal life cycles, long oviposition periods, and refuges in the streambed or neighbouring waterbodies. Species in frequently disturbed streams benefit from these characteristics. Although disturbance may be due to stochastic factors, recovery is not due to chance. Recurring ecological patterns among early colonizers suggest that knowledge of the hydrologic regime, food resources, and dominant taxa can be used to predict the overall resilience of a stream community.

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Resh, Vincent H., Morgan Hannaford, John K. Jackson, Gary A. Lamberti y Patina K. Mendez. "The biology of the limnephilid caddisfly Dicosmoecus gilvipes (Hagen) in Northern California and Oregon (USA) Streams". Zoosymposia 5, n.º 1 (10 de junio de 2011): 413–19. http://dx.doi.org/10.11646/zoosymposia.5.1.34.

Texto completo

Resumen

The limnephilid caddisfly Dicosmoecus gilvipies (Hagen) occurs in many streams of northwestern United States and British Columbia. Because of the large size of the fully grown larva, its synchronous emergence pattern, and its frequent imitation by fly-fishing anglers, D. gilvipes is one of the best known North American aquatic insects. Egg masses are found at the bases of Carex sedges. Cases of early larval instars are made of organic material and detritus; 3rd and 4th instars incorporate pebbles into cases. The 5th-instar case is made entirely of mineral material. Larvae can travel up to 25 m per day, and are predominantly scraper-grazers. Fifth instars attach their cases to the underside of boulders in mid-summer and remain dormant until pupation in autumn. All northern California populations known are univoltine. Adult females use sex pheromones to attract males; most males come to trapped females in the 1st hour after sunset. In laboratory studies, males and females fly during the mate attraction period but generally not at other times. Males but not females exhibit circadian rhythms that govern flight periodicity. In enclosures to study biotic interactions, the density of D. gilvipes larvae has a negative effect on the densities of sessile grazers. This species has been widely used in trophic and behavioral studies conducted in the laboratory and field, and may be a model organism for ecological studies of caddisflies and other benthic macroinvertebrates.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Papadakis, O., K. Tsirintanis, V. Lioupa y S. Katsanevakis. "The neglected role of omnivore fish in the overgrazing of Mediterranean rocky reefs". Marine Ecology Progress Series 673 (2 de septiembre de 2021): 107–16. http://dx.doi.org/10.3354/meps13810.

Texto completo

Resumen

Sea urchins are considered the most important grazers in Mediterranean shallow sublittoral rocky reef ecosystems, but fish can also have an important role in overgrazing and the reduction of habitat complexity. In this study, the trophic behavior of fish was recorded when provided access to experimental surfaces with increased macroalgal biomass and associated benthic fauna, created by herbivore exclusion cages. After a sufficient period for substantial algal growth, the cages were removed and the activity of fish on these surfaces was recorded for 3 h by an automated photographic camera system. Control surfaces with no restriction on grazers were defined on similar substrates for comparison. To quantify the effects of fish feeding activity on macroalgal coverage, photographic samples were taken immediately after the opening of the cages and after each 3 h recording. The response of fish when the cages were removed was immediate and intense. Feeding activity by 13 different fish species was recorded in total, of which the most frequent were the omnivores Diplodus vulgaris, Coris julis and Thalassoma pavo, and to a lesser extent the herbivore Sarpa salpa. The coverage of erect algae was substantially decreased on the experimental surfaces due to fish feeding activity. The algae were either directly consumed by the fish or cut off when the fish were feeding on macroinvertebrates. We conclude that in addition to grazing by herbivores, fish of higher trophic levels can also significantly affect macroalgal assemblages and restrict the recovery of erect algae in overgrazed reefs where prey is scarce.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Lester, Rebecca E., Wendy Wright y Michelle Jones-Lennon. "Does adding wood to agricultural streams enhance biodiversity? An experimental approach". Marine and Freshwater Research 58, n.º 8 (2007): 687. http://dx.doi.org/10.1071/mf06198.

Texto completo

Resumen

Riparian clearing and the removal of wood from channels have affected many streams in agricultural landscapes. As a result, these streams often have depauperate in-stream wood loads, and therefore decreased habitat complexity and lower levels of in-stream biodiversity. The introduction of wood was investigated as a possible rehabilitation technique for agricultural streams. Wood was re-introduced to eight streams in two separate high-rainfall, intensively grazed regions of Victoria, Australia and the effect on aquatic macroinvertebrate communities was measured. The addition of wood increased overall family richness and the richness of most functional feeding groups occupying edge and benthic habitats within the stream. Wood addition led to less overlap between benthic and edge macroinvertebrate communities, suggesting increased habitat heterogeneity within the stream ecosystem. Of all sampled habitats, wood supported the greatest density of families and was colonised by all functional feeding groups. Wood habitats also had the highest overall richness and supported the most taxa that were sensitive to disturbance. These findings suggest that re-introducing wood to agricultural streams is an appropriate rehabilitation technique where those streams are affected by reduced habitat complexity. Additional work is needed to confirm these findings over larger spatial and temporal scales.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Fenoglio, Stefano, José Manuel Tierno de Figueroa, Alberto Doretto, Elisa Falasco y Francesca Bona. "Aquatic Insects and Benthic Diatoms: A History of Biotic Relationships in Freshwater Ecosystems". Water 12, n.º 10 (21 de octubre de 2020): 2934. http://dx.doi.org/10.3390/w12102934.

Texto completo

Resumen

The most important environmental characteristic in streams is flow. Due to the force of water current, most ecological processes and taxonomic richness in streams mainly occur in the riverbed. Benthic algae (mainly diatoms) and benthic macroinvertebrates (mainly aquatic insects) are among the most important groups in running water biodiversity, but relatively few studies have investigated their complex relationships. Here, we review the multifaceted interactions between these two important groups of lotic organisms. As the consumption of benthic algae, especially diatoms, was one of the earliest and most common trophic habits among aquatic insects, they then had to adapt to the particular habitat occupied by the algae. The environmental needs of diatoms have morphologically and behaviorally shaped their scrapers, leading to impressive evolutionary convergences between even very distant groups. Other less evident interactions are represented by the importance of insects, both in preimaginal and adult stages, in diatom dispersion. In addition, the top-down control of diatoms by their grazers contributes to their spatial organization and functional composition within the periphyton. Indeed, relationships between aquatic insects and diatoms are an important topic of study, scarcely investigated, the onset of which, hundreds of millions of years ago, has profoundly influenced the evolution of stream biological communities.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Riley, Leslie, Mark Dybdahl y Robert Hall, Jr. "Invasive Species Impact: Direct and Indirect Interactions Between Two Stream Snails and Their Algal Resources". UW National Parks Service Research Station Annual Reports 28 (1 de enero de 2004): 61–69. http://dx.doi.org/10.13001/uwnpsrc.2004.3577.

Texto completo

Resumen

We measured the strength of direct and indirect interactions in order to develop a standardized estimate of the impact of an invasive snail on its resource and a competitor. The freshwater New Zealand snail, Potamopyrgus antipodarum, an invasive species in the western U.S., is the most abundant benthic macroinvertebrate grazer in several rivers, where it overlaps with several threatened endemic snails. In one watershed, Potamopyrgus coexists with the snail, Pyrgulopsis robusta, which may be affected by resource competition with Potamopyrgus. In field enclosure experiments, we quantified the direct grazing effect of snails on algae and the indirect effects between consumers. Potamopyrgus significantly limited growth of Pyrgulopsis. In contrast, Pyrgulopsis appeared to facilitate growth of the invasive snail (Potamopyrgus). In natural populations, snail densities were positively correlated over five sites, but negatively correlated at two downstream sites. Interaction strengths between snails and algae were equivalent for both snails at both sites, indicating that invasion success could not be attributed to differences in resource acquisition. However, the overall impact of the invader was much higher at the downstream site when both snail abundance and interaction strengths were considered. Negative individual effects of Potamopyrgus at two trophic levels in conjunction with high Potamopyrgus abundance demonstrated a significant impact of the invader in this lotic community.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Pastorino, Paolo, Annalisa Zaccaroni, Alberto Doretto, Elisa Falasco, Marina Silvi, Alessandro Dondo, Antonia Concetta Elia, Marino Prearo y Francesca Bona. "Functional Feeding Groups of Aquatic Insects Influence Trace Element Accumulation: Findings for Filterers, Scrapers and Predators from the Po Basin". Biology 9, n.º 9 (14 de septiembre de 2020): 288. http://dx.doi.org/10.3390/biology9090288.

Texto completo

Resumen

For this study, we measured the concentrations of 23 trace elements (Al, As, Ba, Bi, Cd, Cr, Co, Cu, Fe, Ga, Hg, In, Li, Mn, Mo, Ni, Pb, Se, Sr, Ti, Tl, V, and Zn) in the whole bodies of three functional feeding groups (FFG) (filterers—Hydropsychidae, scrapers—Heptageniidae, and predators—Odonata) of aquatic insects collected from two sites in the Po basin (Po Settimo and Malone Front, Northwest Italy) to determine: (a) how FFG influence trace element accumulations, (b) if scrapers accumulate higher elements compared to the other FFG, since they graze on periphyton, which represents one of the major sinks of metals, and (c) the potential use of macroinvertebrates to assess the bioavailability of trace elements in freshwater. The hierarchical clustering analysis generated three main groups based on trace element concentrations: the most abundant elements were Fe and Al, followed by Sr, In, Zn, V, Mo, and Cu. Tl was below the limit of detection (LOD) in all FFG. Ga was detected only in scrapers from both sites and Hg only in predators from Po Settimo. The principal component analysis showed that concentrations of Al, As, Bi, Cd, Co, Cr, Ga, Fe, In, Mn, Pb, Ni, and Sr were highest in scrapers, suggesting that trace elements accumulate from the ingestion of epilithic periphyton (biofilm). Odonata (predators) accumulate certain elements (Ba, Hg, Li, Se, V, Ti, and Zn) in higher concentrations by food ingestion composed of different aquatic organisms. Differently, Cu and Mo concentrations were the highest in filterers due to their bioavailability in the water column. Non-metric multidimensional scaling clearly differentiated the FFG based on their ability to accumulate trace elements. The findings from this study represent an important step toward the definition of an innovative approach based on trace element accumulation by macroinvertebrates.

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Yeung, Alex C. Y. y David Dudgeon. "A manipulative study of macroinvertebrate grazers in Hong Kong streams: do snails compete with insects?" Freshwater Biology, agosto de 2013, n/a. http://dx.doi.org/10.1111/fwb.12210.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Barry, Savanna C., A. Challen Hyman, Charles A. Jacoby, Laura K. Reynolds, Michal Kowalewski y Thomas K. Frazer. "Variation in Seagrass-Associated Macroinvertebrate Communities Along the Gulf Coast of Peninsular Florida: An Exploration of Patterns and Ecological Consequences". Frontiers in Marine Science 8 (4 de marzo de 2021). http://dx.doi.org/10.3389/fmars.2021.596966.

Texto completo

Resumen

Seagrasses form vast meadows of structurally complex habitat that support faunal communities with greater numbers of species and individuals than nearby unstructured habitats. The Gulf coast of peninsular Florida represents a natural laboratory ideally suited to the study of processes that shape seagrass-associated invertebrate and fish communities within meadows of a single species of seagrass, Thalassia testudinum. This suitability arises from a pronounced structural and chemical gradient that exists over ecologically relevant spatial and temporal scales, as revealed by extensive monitoring of water quality and seagrass. We hypothesized that seagrass-associated invertebrate communities would vary across five estuarine systems spread along a spatial gradient in phosphorus concentration, an important driver of seagrass and phytoplankton growth in this region. The quantitative results based on data acquired at 25 stations (75 samples, 52,086 specimens, and 161 taxa) indicated that each of the five estuarine systems were distinct with regard to species composition and differences among systems were driven by abundant or relatively common species. In addition, we found evidence to indicate food webs in seagrass meadows along this gradient may differ, especially in the relative dominance of algal grazers and predatory invertebrates. These changes in species composition and trophic roles could be driven by phosphorus directly, through increases in rates of primary production with higher concentrations of phosphorus, or indirectly, through nutrient-mediated changes in the physical structure of the seagrass canopy. Our results suggest that differences in the habitat created by T. testudinum under differing phosphorus supplies lead to ecologically significant shifts in macroinvertebrate communities.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Rubio-Gracia, Francesc, María Argudo, Lluís Zamora, William H. Clements, Anna Vila-Gispert, Frederic Casals y Helena Guasch. "Response of stream ecosystem structure to heavy metal pollution: context-dependency of top-down control by fish". Aquatic Sciences 84, n.º 2 (1 de febrero de 2022). http://dx.doi.org/10.1007/s00027-022-00849-4.

Texto completo

Resumen

AbstractThe stress-gradient hypothesis predicts that biotic interactions within food webs are context dependent, since environmental stressors can attenuate consumer–prey interactions. Yet, how heavy metal pollution influences the impacts of predatory fish on ecosystem structure is unknown. This study was conducted in the Osor stream (Spain), which features a metal (mainly Zn) pollution gradient. We aimed to determine how the responses of benthic communities to the presence and absence of predatory fish interact with environmental stress and to test whether the top-down control of top predators is context dependent. To address these questions, periphyton biomass and macroinvertebrate densities were determined throughout an exclosure/enclosure mesocosm experiment using the Mediterranean barbel (Barbus meridionalis) as a top predator. The monitoring study showed that metal accumulation in periphyton and macroinvertebrates reflected patterns observed in water. The mesocosm study showed that fish predation effects on larval chironomids were not context-dependent and that periphyton biomass was markedly lower in the presence of fish regardless of metal pollution levels. This strong top-down control on periphytic algae was attributed to the foraging behaviour of fish causing bioturbation. In contrast, the top predator removal revealed grazer-periphyton interactions, which were mediated by heavy metal pollution. That is, periphyton benefitted from a lower grazing pressure in the metal-polluted sites. Together, our results suggest that the top–down control by fishes depends more on functional traits (e.g. feeding behaviour) than on feeding guild, and demonstrate the capacity of top predators to modify anthropogenic stressor effects on stream food-web structure.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Traiger, Sarah B. "Effects of elevated temperature and sedimentation on grazing rates of the green sea urchin: implications for kelp forests exposed to increased sedimentation with climate change". Helgoland Marine Research 73, n.º 1 (11 de septiembre de 2019). http://dx.doi.org/10.1186/s10152-019-0526-x.

Texto completo

Resumen

Abstract Sea urchin grazing rates can strongly impact kelp bed persistence. Elevated water temperature associated with climate change may increase grazing rates; however, these effects may interact with local stressors such as sedimentation, which may inhibit grazing. In Alaska, glacial melt is increasing with climate change, resulting in higher sedimentation rates, which are often associated with lower grazer abundance and shifts in macroalgal species composition. The short-term effects of elevated temperature and sediment on grazing were investigated for the green sea urchin, Strongylocentrotus droebachiensis (O.F. Müller, 1776), in Kachemak Bay, Alaska (59° 37′ 45.00″ N, 151° 36′ 38.40″ W) in early May 2017. Feeding assays were conducted at ambient temperature (6.9–9.8 °C) and at 13.8–14.6 °C with no sediment and under a high sediment load. Grazing rates significantly decreased in the presence of sediment, but were not significantly affected by temperature. Along with sediment impacts on settlement and post-settlement survival, grazing inhibition may contribute to the commonly observed pattern of decreased macroinvertebrate grazer abundance in areas of high sedimentation and increased sedimentation in the future may alter sea urchin grazing in kelp forests.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Gizzi, Francesca, João Gama Monteiro, Rodrigo Silva, Susanne Schäfer, Nuno Castro, Silvia Almeida, Sahar Chebaane et al. "Disease Outbreak in a Keystone Grazer Population Brings Hope to the Recovery of Macroalgal Forests in a Barren Dominated Island". Frontiers in Marine Science 8 (8 de junio de 2021). http://dx.doi.org/10.3389/fmars.2021.645578.

Texto completo

Resumen

Macroalgal forests play a key role in shallow temperate rocky reefs worldwide, supporting communities with high productivity and providing several ecosystem services. Sea urchin grazing has been increasingly influencing spatial and temporal variation in algae distributions and it has become the main cause for the loss of these habitats in many coastal areas, causing a phase shift from macroalgae habitats to barren grounds. The low productive barrens often establish as alternative stable states and only a major reduction in sea urchin density can trigger the recovery of macroalgal forests. The present study aims to assess if the 2018 disease outbreak, responsible for a strong reduction in the sea urchin Diadema africanum densities in Madeira Island, was able to trigger a reverse shift from barren grounds into macroalgae-dominated state. By assessing the diversity and abundance of benthic sessile organisms, macroinvertebrates and fishes before, during and after that particular mass mortality event, we evaluate changes in benthic assemblages and relate them to variations in grazer and herbivore densities. Our results revealed a clear shift from barren state to a macroalgae habitat, with barrens characterized by bare substrate, sessile invertebrate and Crustose Coralline Algae (CCA) disappearing after the mortality event. Overall variations in benthic assemblages was best explained by four taxa (among grazers and herbivores species). However, it was the 2018 demise of D. africanum and its density reduction that most contributed to the reverse shift from a long stable barren state to a richer benthic assemblage with higher abundance of macroalgae. Despite this recent increase in macroalgae dominated habitats, their stability and persistence in Madeira Island is fragile, since it was triggered by an unpredictable disease outbreak and depends on how D. africanum populations will recover. With no control mechanisms, local urchin populations can easily reach the tipping point needed to promote a new shift into barren states. New conservation measures and active restoration are likely required to maintain and promote the local stability of macroalgal forests.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "Macroinvertebrate grazers"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros