An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Ascophyllum nodosum; Balanus; Fucus; Mytilus edulis; algae; cages; canopy; carnivores; community structure; conservation areas; experimental design; herbivores; interspecific competition; intraspecific competition; littoral zone; microhabitats; mussels; population ecology; predation; predators; prey species; shade; snails; species richness; spring; stainless steel; storms; summer; winter; Maine; Massachusetts; New England region
Abstract:
... The influences of predation, competition, biological disturbance, exposure to wave action, and inclination and heterogeneity of the substratum on the structure of the rocky intertidal community of New England were studied with a combination of experiments and observations at six areas in Maine and Massachusetts from 1972—1975. Several aspects of community structure (seasonal utilization of primary ...
Scleractinia; browsing; cages; community structure; corals; fish; fish feeding; grazing; habitats; mucus; reefs; Guam
Abstract:
... Controlled coral transplant experiments were used to determine the effect of piscine corallivores on growth, zonation, and distribution of scleractinian corals in Guam. Pocillopora damicornis L. generally occurs only on the reef flat, reef margin (crest), and in lagoon habitats of the Indo—West Pacific. Although P. damicornis grows in deeper reef habitats in the eastern Pacific, it is seldom found ...
cages; community structure; habitats; invertebrates; predators; streams; Colorado; Wisconsin
Abstract:
... Densities of invertebrates were manipulated within stony substrate filled cages in a Wisconsin and a Colorado stream to test the effects of prey densities on colonizaiton of the cages by invertebrate predators and potential competitors. There was no difference between the number of predators colonizing cages with high initial prey densities and that the colonizing cages with zero initial prey dens ...
... The effects of predation and spatial heterogeneity on the benthic macroinvertebrates in the littoral zone of a pond were investigated in a year—long caging experiment. Bluegill sunfish stocked at three densities within the cages were used as the predator. Heterogeneity was manipulated using artificial macrophytes. The presence of plants led to increases both in species richness and in density of m ...
Lepomis macrochirus; Odonata; cages; censuses; community structure; fish; freshwater; habitats; lakes; littoral zone; macroinvertebrates; nuclear power industry; predation; prey species; spatial variation; species abundance; Florida
Abstract:
... I studied the impact of variable predation by bluegill sunfish on macroinvertebrate prey in a North Florida lake. Underwater time—lapse cinematography and censuses of bluegill abundances in shallow, middepth, and deep habitats permitted estimation of predation intensity and variability within and among lake habitats. I then incorporated predation rates typical of the middepth zone in caging experi ...
Acanthuridae; Labridae; Muraenidae; Pomacentridae; cages; community structure; coral reefs; fish communities; grouper; juveniles; larvae; mortality; piscivores
Abstract:
... Demographically open communities are often viewed as stochastically structured assemblages because most colonizing juveniles arrive via unpredictable dispersal mechanisms. However, interactions between established residents and incoming juveniles may affect juvenile persistence in species‐specific ways and could therefore impose a degree of determinism on future community structure. Using 16 spati ...
Iridomyrmex purpureus; baits; cages; community structure; fauna; foraging; sandstone; social dominance; surveys; Australia
Abstract:
... Ant communities are thought to consist of a competitive hierarchy of interacting species, with an assemblage of subordinate species being structured by a dominant species. Mensurative and behavioral studies suggest a significant role for competition in structuring ant communities, although there are few experimental studies to support this contention. We examined the effect of the dominant ant Iri ...
... Tuna farming is based on fishing bluefin tuna in their natural habit of the western Mediterranean and fattening them in floating cages. Although this type of aquaculture is expanding rapidly in the Mediterranean Sea, very little information is available for an environmental impact assessment and environmental monitoring of tuna ranching. Spatial and temporal scales of impact need to be established ...
fish culture; fish farms; aquatic plant culture; community structure; Phaeophyceae; community facilities; Cyanobacteria; periphyton; Chlorophyceae; cages; Rhodophyta; Bacillariophyceae; Tyrrhenian Sea; Sicily
Abstract:
... An algal assemblage growing on artificial substrata of fish-farm cages was investigated. Specifically, algal response to the effects of fish-farm facilities was studied, in order to identify a possible future descriptor of biodeposition impact. Some sites were positioned upstream of the farms (at least 750 m; 'controls') and other sites were positioned downstream of the farms ('impacts'). All site ...
... Consumer effects on prey are well known for cascading through food webs and producing dramatic top-down effects on community structure and ecosystem function. Bottom-up effects of prey (primary producer) biodiversity are also well known. However, the role of consumer diversity in affecting community structure or ecosystem function is not well understood. Here, we show that herbivore species richne ...
Ascidiacea; Bryozoa; Cirripedia; cages; community structure; corals; granite; larvae; macroalgae; mortality; phototaxis; predation; shade; tropics; water flow; Gulf of Maine
Abstract:
... Dramatic shifts in community composition occur between vertical and horizontal rocky surfaces in subtidal environments worldwide, yet the forces mediating this transition are poorly understood. Vertical rock walls are often covered by lush, diverse communities of sessile suspension‐feeding invertebrates, while adjacent horizontal substrates are dominated by algae, or corals in the tropics. Multipl ...
Sargassum linearifolium; cages; community structure; epiphytes; field experimentation; fish; grazing; habitats; herbivores; invertebrates; macroalgae; plant communities; primary productivity; seagrasses
Abstract:
... 1. Herbivory is particularly intense in marine environments, with a higher proportion of primary productivity removed than in terrestrial habitats. Experimental manipulation of large herbivores (fish, urchins) has clearly documented their grazing impacts on algal and seagrass beds. Grazing impacts of mesograzers (small invertebrates such as amphipods and isopods) are, however, less understood due ...
... Much theory has been developed to explore how competition for shared resources (exploitation competition) or the presence of shared natural enemies (apparent competition) might structure insect and other communities. It is harder to predict what happens when both processes operate simultaneously. We describe an experiment that attempted to explore how shared natural enemies and resource competitio ...
Zostera marina; biomass; cages; community structure; edge effects; fish; habitats; predation; predators; surveys; California
Abstract:
... Habitat structure at many scales influences faunal communities. Although habitat structure at different scales often covaries, studies rarely examine the relative effects of structure at multiple scales on faunal density and diversity. In shallow-water seagrass systems, epifaunal density at local scales generally increases with increased habitat structural complexity (e.g. shoot density per unit a ...
Anisakis; Thunnus thynnus; aquaculture; cages; community structure; decision support systems; harvest date; longevity; models; monitoring; nestedness; parasites; parasitology; pathogens; rearing; species diversity; tuna
Abstract:
... Tuna (Thunnus spp.) has been characterized by long distance migrations, highly predatory behavior and longevity, all of which in turn, enable infections with a wide spectrum of different parasitic groups, reflecting in a remarkable diversity of tuna parasite communities. Since 2003, we have been monitoring parasite communities of Atlantic bluefin tuna (Thunnus thynnus) that are caught from the wil ...
reptiles; trees; forests; Tiliqua; pitfall traps; Eucalyptus marginata; ecosystems; frogs; harvesting; temporal variation; Acacia melanoxylon; autumn; community structure; monitoring; variance; foxes; species diversity; cages; logging; Bettongia; spring; Trichosurus vulpecula; Dasyurus; shelterwood systems; stand basal area; Vulpes vulpes; Western Australia
Abstract:
... Summary Terrestrial vertebrate associations with silviculture and other factors were investigated as part of the FORESTCHECK monitoring program in the jarrah (Eucalytpus marginata) forests of south-west Western Australia. A total of 48 integrated monitoring grids form the basis of this study—sampled over five years (2001–2006), across five ecosystem-defined regions (one sampled per year), each wit ...
Anabaenopsis; Copepoda; Oreochromis niloticus; Pediastrum; Rotifera; ammonium nitrogen; cage culture; cages; case studies; community structure; fish; fish culture; fish feeds; fish ponds; fish waste; highlands; nutrient content; nutrients; oxygen; phosphorus; phytoplankton; valleys; water quality; water reservoirs; zooplankton; Ethiopia
Abstract:
... The potential impact of Nile Tilapia (Oreochromis niloticus) cage culture on water quality and pelagic community composition was investigated in two Ethiopian small water bodies, one located in the highlands (Yemlo) and the other in the Great Rift Valley (Allage). This study was designed to assess the difference between the cages and open water in relation to those water quality changes attributab ...
Megalobrama amblycephala; animal growth; antioxidant activity; cages; chlorides; community structure; copper; feed conversion; feed supplements; fish feeding; immune response; intestines; kidneys; liver; microorganisms; weight gain
Abstract:
... A study was conducted to investigate the effects of dietary tribasic copper chloride on growth, copper status, antioxidant activities, immune responses and intestinal microflora in blunt snout bream, Megalobrama amblycephala. Eight practical diets containing different levels of copper (0, 3, 6, 9, 25, 50, 100 and 150mg Cukg⁻¹) from tribasic copper chloride were fed to blunt snout bream (31g of ini ...
Lytechinus; Tripneustes; Ulva; algae; benthic organisms; cages; community structure; ecosystems; grazing; habitats; islands; species diversity; Galapagos Islands
Abstract:
... Theory and experiments indicate that changes in consumer diversity affect benthic community structure and ecosystem functioning. Although the effects of consumer diversity have been tested in the laboratory and the field, little is known about effects of consumer diversity in the subtidal zone, one of the largest marine habitats. We investigated the grazing effects of sea urchins on algal abundanc ...
Copepoda; Nematoda; Polychaeta; biodiversity; cages; carbon; chemistry; community structure; fish culture; fish farms; lipids; proteins; sediments; Mediterranean Sea; Sicily
Abstract:
... This study aimed to detect the impact of organic loads due to biodeposition from a fish farm in an exposed area of the Strait of Sicily, Mediterranean Sea. Sediment chemistry and meiofaunal assemblages were investigated on a seasonal basis at four stations: two from the impacted area and two control stations. The presence of the cages induced a significant accumulation of proteins, lipids and biop ...
... Cages and fertilizers were used at Glover’s Atoll, Belize to test the relative importance of nitrogen (N) and phosphorus (P) to microbial euendolithic communities (bacteria, algae and fungi) and their bioerosion rates of Strombus gigas shells after 56-days of exposure. By the end of the experiment, the abundance of green algae was higher than cyanobacteria and fungi in N and N+P treatments, althou ...
Bacillariophyceae; Prorocentrum; ammonium compounds; cages; cold season; community structure; eutrophication; fish culture; fish farms; interspecific variation; phytoplankton; power plants; species diversity; temperature; thermal stress; toxicity; water pollution; winter; East China Sea
Abstract:
... Six cruises were conducted in a fish farm adjacent to the Ninghai Power Plant in Xiangshan Bay, East China Sea. Fish farming significantly increased NH4+, DIP, and TOC concentrations, while it significantly decreased the DO level. These increase/decrease trends were more pronounced in warmer seasons. Although culture practices did not significantly increase phytoplankton density, it drastically en ...
Cancer plebejus; Romaleon polyodon; biomass; cages; community structure; crabs; ecosystems; fisheries; habitats; landscapes; macroinvertebrates; predators; sediments; species diversity; traditional technology
Abstract:
... Although large crabs are recognized as important sediment disturbers influencing the structure of benthic communities, the role of dominant predatory crabs in soft-bottom habitats along the Humboldt Current Ecosystem, remains largely unknown. A field study was conducted, hypothesizing that the digging activity of these predators disturbs the habitat thereby leading to a reduction in individual abu ...
... The loss of large‐bodied herbivores and/or top predators has been associated with large‐scale changes in ecosystems around the world, but there remain important questions regarding the contexts in which such changes are most likely and the mechanisms through which they occur, particularly in marine ecosystems. We used long‐term exclusion cages to examine the effects of large grazers (sea cows, Dug ...
altitude; biodiversity; cages; cerrado; community structure; habitats; small mammals; tropical montane cloud forests; Brazil
Abstract:
... The Chapada das Perdizes is considered a region of high biodiversity, but there are few studies that describe the small mammals in the region, mainly in higher portions of the area. The primary objective of this study was to estimate the richness and abundance of terrestrial small mammals within three different vegetation types in the high altitude region of southern Minas Gerais and to evaluate t ...
Chorthippus parallelus; cages; community structure; ecosystems; egg masses; eutrophication; females; food plants; grasshoppers; grasslands; insect pests; land use; males; nymphs; phytophagous insects; plant communities; rearing; species diversity
Abstract:
... In many environments land use intensification is likely to result in a decrease in species richness and in an increase in eutrophication. Although the importance of both factors for higher trophic levels such as insect herbivores is well documented, their impact has rarely been studied in combination. Herbivorous insects have a strong impact on the functioning of ecosystems and it is therefore imp ...
Rattus rattus; adults; age structure; cages; coastal forests; community structure; habitats; juveniles; population size; rats; small mammals; trapping; traps; Australia
Abstract:
... Trapping is an invaluable tool for estimating community composition and population size and structure of mammals. Bias in the relative contribution of species to a community and the age and sex structure of populations can occur where the traps used do not equally trap all species, sexes or cohorts. The aim of this study was to compare the efficiency of enclosed Elliott traps and open wire cage tr ...
Hiatella arctica; Mytilus edulis; Polysiphonia; Saccharina; Salmo salar; aquaculture; biofouling; biomass production; cages; community structure; fish farms; larynx; mussels; salmon; species diversity; Norway
Abstract:
... The accumulation of biofouling on cage nets is a major problem and cost factor in finfish aquaculture worldwide. Norway is one of the main producers of Atlantic salmon, but biofouling on salmon farms has not been studied systematically. In a 1-year field study at a commercial salmon farm in Central Norway the effects of immersion period (1, 3, 6 and 12months), sampling time, mesh size (13 and 25mm ...
... Recent research has shown that agricultural management affects microbial biomass and community composition. We investigated the functional implications of such effects in terms of barley biomass production and nutrient acquisition, and whether changes in barley nutrient status affected aphid fecundity. Soils were collected from conventional, ley and organic arable fields and used as inocula in a g ...
cages; community structure; environmental factors; fish culture; marine sediments; pellets; phosphorus; species diversity; trace elements; water pollution; Croatia
Abstract:
... Effects on sediments of fish farming activity near Vrgada Island was analysed through living and total foraminiferal assemblages and concentration of major, minor and trace elements from three sediment cores. Elemental concentrations of sediments are in accordance with carbonate characteristics of the surrounding area and show mostly natural element variations between sampling locations and throug ...
... Stream ecosystems receive large quantities of nutrients from terrestrial ecosystems that influence community dynamics. However, few studies have investigated the effects of subsidiary calcium, an essential element of animals, on stream ecosystems. We focused on differences in calcium concentrations of leaf litter between tree species. In particular, litter of Japanese cedar (Cryptomeria japonica) ...
Ulva; biochemical oxygen demand; biomass; cages; community structure; ecosystems; environmental health; estuaries; eutrophication; fauna; field experimentation; herbivores; invertebrates; littoral zone; macroalgae; moieties; organic matter; sediments; species diversity; suspension feeding; California
Abstract:
... Eutrophication, defined as the accumulation of organic matter typically in response to anthropogenically enhanced nutrient inputs, often takes the form of macroalgal blooms in shallow estuaries and causes a cascade of adverse ecosystem effects. Confidence in the use of macroalgae as an indicator of eutrophication in estuaries is limited by the lack of quantitative data on thresholds of adverse eff ...
Amphipoda; Bryozoa; Platyhelminthes; cages; community structure; invertebrates; predation; predators
Abstract:
... Large consumers are important in determining community structure and have been extensively researched. The impact of predation on hard-substrate marine invertebrate communities tends to be mixed. Numerous exclusion studies fail to incorporate appropriate procedural controls or account for meso-predators. An experimental exclusion study was performed to investigate the effects of large predators on ...
biomass; cage culture; cages; community structure; conservation areas; farmed fish; farms; fish communities; fishermen; gillnets; indigenous species; species diversity; Lake Malawi; Malawi
Abstract:
... Local fishermen claim that introduction of a commercial cage aquaculture farm in Lake Malawi resulted in low fish catches as fish take refuge within the farm. Fish specimens were caught in three fishing sites, one at the farm and two at 5km southeast and northwest of the farm in February, April, June, and August 2012 using four experimental multi-mesh gillnets with similar dimensions to catch diff ...
bacterial communities; cages; chlorophyll; community structure; denaturing gradient gel electrophoresis; effluents; fish culture; fish farms; phylogeny; redox potential; sediments; Greece
Abstract:
... We investigated changes in sediment bacterial community structure across a spatial organic enrichment gradient associated with fish farms in two different sites in the Eastern Mediterranean (Greece). The observed trend was similar at both fish farms even though they are far from each other. The mean number of the most abundant operational taxonomic units (OTUs) was not significantly different, eit ...
benthic organisms; cages; carbon nitrogen ratio; coasts; community structure; coral reefs; eutrophication; fish; herbivores; invertebrates; lawns and turf; macroalgae; monitoring; nutrient content; nutrients; organic matter; overfishing; tiles; Costa Rica
Abstract:
... Overfishing and nutrient enrichment are among the major local stressors to coral reefs worldwide, as they can alter the benthic reef community by promoting fast growing algae and bioeroders. The Northern coast of Pacific Costa Rica is strongly influenced by seasonal upwelling events that naturally increase nutrient concentrations between December and March. This study therefore investigated the co ...
Caprella; Gammaridae; Zostera marina; cages; community structure; eutrophication; field experimentation; habitats; herbivores; nutrients; overfishing; predation; predators; slow-release fertilizers; species diversity
Abstract:
... Herbivore communities can be sensitive to changes in predator pressure (top‐down effects) and resource availability (bottom‐up effects) in a wide range of systems. However, it remains unclear whether such top‐down and bottom‐up effects reflect direct impacts of predators and/or resources on herbivores, or are indirect, reflecting altered interactions among herbivore species. We quantified direct a ...
... Seasonal effects of waterfowl (Fulica atra and Anas platyrhynchos) grazing on submerged macrophytes (Ruppia cirrhosa and Potamogeton pectinatus) and the mediating role of flowers on plant consumption were evaluated by exclusion cages and tethering experiments deployed in a Mediterranean lagoon throughout the annual cycle. Despite the low waterfowl abundance recorded in summer, exclusion-cage exper ...
Atrina; Charybdis; adults; bioturbation; breeding; cages; community structure; crabs; ecosystems; fauna; sediments; stomach; New Zealand
Abstract:
... The Portunid crab Charybdis japonica was first found in Waitemata Harbour, New Zealand, in 2000. It has established breeding populations and has been spreading, yet information on its dietary preferences in New Zealand are unknown. We conducted field caging experiments to elucidate prey choices and potential impacts of Charybdis on benthic communities. We tested the hypothesis that Charybdis would ...
Calomys; Cavia; Didelphis albiventris; Mus musculus; Oligoryzomys; Rattus norvegicus; cages; community structure; dairy farming; disease transmission; financial economics; food storage; habitats; humans; indigenous species; livestock and meat industry; milk; opossums; pest control; pests; poisoning; production technology; rodenticides; rodents; sheds; small mammals; swine; swine production; traps; Argentina
Abstract:
... Some rodent species are considered important pests around the world because they cause economic losses and sanitary problems. Although rodents are found in many different environments, they select habitat patches where resources are available. There is scant information regarding community composition and habitat distribution of small mammals in dairy and pig production systems. The aim of this re ...
Sheila Mae S Santander – de Leon; Wolfgang Reichardt; Shielameh Peralta‐Milan; Maria Lourdes San Diego‐McGlone; Sharon Nonato Nuñal; Hongyi Wei; Takeshi Yoshikawa; Suguru Okunishi; Hiroto Maeda
Bacteroidetes; Chanos chanos; anaerobic conditions; bacterial communities; cages; community structure; delta-Proteobacteria; denitrifying bacteria; farms; fish; fish culture; fish feeds; gel electrophoresis; redox potential; sediments; sulfate-reducing bacteria; Philippine Sea
Abstract:
... Bacterial communities in sediments underneath milkfish cages and adjacent off‐cage areas in Bolinao, Lingayen Gulf, West Philippine Sea were characterized using PCR‐denaturing gradient gel electrophoresis to assess influence of the fish farming to the sediments. The sediments in the fish cage (FC) area showed anoxic conditions [redox potential of −165 to −213 mV and acid‐volatile sulphide‐sulphur ...
biomass production; cages; community structure; fouling; herbivores; interspecific variation; marine ecosystems; predation; predators; primary productivity; species diversity; Argentina
Abstract:
... Predatory control of community structure, through consumption of herbivores and subsequent positive effects on the biomass or productivity of primary producers is common in marine ecosystems. We designed an experiment to analyse the effect of large-sized predators on the development of the macrofouling assemblage of a harbour. Predation was manipulated by randomly assigning artificial substrata to ...
Caprella; Posidonia oceanica; biomass; cages; community structure; meadows; predation; predatory fish
Abstract:
... Amphipod assemblages that inhabit Posidonia oceanica seagrass meadows are potentially relevant trophic resources for ichthyofauna. However, the effects of fish predation on amphipod assemblages in this system have received little attention. To address this gap in knowledge, experimental manipulations of predation intensity (exclusion and inclusion cages) were conducted at two sites in a Mediterran ...
... Non‐random species associations occur in naturally sampled parasite communities. The processes resulting in predictable community structure (e.g. particular host behaviours, cross‐immunity, interspecific competition) could be affected by traits that vary within a parasite species, like growth or antigenicity. We experimentally infected three‐spined sticklebacks with a large tapeworm (Schistocephal ...
cages; community structure; forest trees; granivores; mammals; predation; rain forests; seedlings; seeds; species diversity; species recruitment; tropical forests
Abstract:
... The recruitment of seedlings from seeds is the key demographic transition for rain forest trees. Though tropical forest mammals are known to consume many seeds, their effects on tree community structure remain little known. To evaluate their effects, we monitored 8,000 seeds of 24 tree species using exclosure cages that were selectively permeable to three size classes of mammals for up to 4.4 year ...
Fucus vesiculosus; Phalacrocorax carbo sinensis; algae; biodiversity; cages; community structure; fish; fish communities; grazing intensity; herbivores; islands; piscivores; population growth; predation; reproduction; runoff; seabirds; trophic levels; Baltic Sea
Abstract:
... Expanding populations of the piscivorous seabird Great Cormorant (Phalacrocorax carbo sinensis) in the Baltic Sea can have both bottom-up and top-down effects on lower trophic levels: nutrient runoff (bottom-up) from colonies increases algal growth, while predation on fish (top-down) can lead to decreased fish populations around colonies, potentially causing a trophic cascade and higher grazing pr ...
Dictyota; Galaxaura; Halimeda opuntia; Moorea; Padina; cages; community structure; coral reefs; food webs; herbivorous fish; macroalgae; French Polynesia
Abstract:
... While the importance of top‐down control by grazers in maintaining tropical reef community structure is well known, the effect of ‘fishing down the food web’, which simultaneously changes the abundance and size of herbivorous fishes, has received less attention. As many fishing practices target the biggest fish and regulations often set minimum size limits, understanding size‐dependency of this co ...
... Eukaryotes commonly host communities of heritable symbiotic bacteria, many of which are not essential for their hosts' survival and reproduction. There is laboratory evidence that these facultative symbionts can provide useful adaptations, such as increased resistance to natural enemies. However, we do not know how symbionts affect host fitness when the latter are subject to attack by a natural su ...
Cirripedia; Gastropoda; Markov chain; Mytilus edulis; Ralfsia; Tautogolabrus adspersus; autumn; birds; cages; carnivores; community structure; environmental factors; hydrodynamics; littoral zone; models; mortality; mussels; predation; species diversity; spring; summer; winter; Gulf of Maine
Abstract:
... In intertidal communities, consumers (especially carnivorous gastropods) have historically been thought to exert strong top-down control on community composition by regulating competitively dominant mussels and barnacles. This paradigm was formulated based on wire mesh cage exclusion experiments, which have well-known artifacts such as altering hydrodynamics and excluding non-target, but potential ...
... Immune measures and the fecal bacterial community were examined in female Biobreeding rats housed in wire bottom cages (wire) or in solid bottom cages containing hardwood chips (bedding). Housing did not affect food intake, weight gain, fecal output or fibre content, serum liver enzymes, or spleen and mesenteric lymph node immune cell populations. Bedding-housed rat feces were enriched in phylotyp ...