Direct Food Source Research Articles

A preliminary study of macrofaunal communities and their carbon and nitrogen stable isotopes in the Haima cold seeps, South China Sea

The macrofaunal community in the Haima cold seeps of the South China Sea was investigated, and trophic relationships were evaluated using carbon and nitrogen stable isotope signatures (δ13C and δ15N). A total of 30 macrofaunal species were identified in this study, most of which were collected from the Gigantidas haimaensis mussel beds. Only four macrofaunal species were collected from the Calyptogena marissinica clam beds, where the environment may not be suitable for the survival of most macrofauna. The bush of slim tubeworms (Sclerolinum sp.) might be an important nursery ground for mussels. G. haimaensis was the predominant species, and its average δ13C and δ15N values were −52.7‰ and 0.6‰, respectively. Compared with the stable isotope signatures of particulate organic matter (POM), it suggested that the food source of macrofauna in the Haima cold seeps was mainly originated from chemosynthetic autotrophs. In the mussel bed, most of the macrofauna had a large δ13C isotopic distance compared with G. haimaensis, suggesting that G. haimaensis was not a direct food source for most cold-seep macrofauna in the mussel bed. The variation in stable isotope signatures of macrofauna might be attributed to different proportions of methanotrophic and thiotrophic endosymbionts. Neolithodes brodiei and Bathynomus jamesi showed the highest δ13C and δ15N values. However, the large isotopic distance indicated that N. brodiei and B. jamesi might just occasionally visit the cold-seep ecosystem and their food sources were mainly from the upper ecosystem relying on photosynthesis. Overall, our results suggested that there was no significant predator-prey relationship among these macrofaunal species in the Haima cold seeps. This study provided important baseline data of stable isotope signatures for further studies to elucidate the trophic interaction among seep organisms.

Food Sources of Benthic Communities at the Caiwei Guyot and Yap Trench, Northwestern Pacific Ocean: Inferences From Carbon and Nitrogen Isotopes

AbstractTo investigate nutritional resources for benthic communities at two sites in the northwestern Pacific Ocean (the Caiwei Guyot and the Yap Trench), stable isotopes of carbon and nitrogen (δ13C and δ15N) were measured in the tissues of megabenthic consumers (Porifera, Asteroidea, Crinoidea, Holothuroidea, Ophiuroidea, Gammaridea, and Actiniaria) as well as four potential food sources (suspended particles, sinking particles, zooplankton, and sedimentary organic matter). Fast‐sinking particles are generally thought to be the primary food source for benthic consumers, but that paradigm does not seem to apply at these abyssal sites. Here the δ13C and δ15N signatures of fast‐sinking particles (as collected by sediment traps; δ13C = −24.1 to −22.6‰, δ15N = 1.4 to 5.4‰) were significantly lower than those of the megabenthos (δ13C = −20.1 to −16.1‰, δ15N = 10.2 to 17.9‰), indicating that these particles are not likely a direct food source for the animals. Buoyant particles (and slow‐sinking particles), on the other hand, seem to be a significant direct food source for the megabenthos. Sedimentary organic matter and zooplankton are also important direct food sources. Trophic level analysis similarly indicates a diversity of food sources and suggests that for at least some animals, microbes (e.g., bacteria) may be a food source as well.

Material cycling in coastal waters and the role of the Kiritappu Wetland in Hamanaka, Hokkaido: An analysis using the surf clam (Pseudocardium sachalinense) as an environmental indicator

Abstract The suspension feeding benthic bivalve surf clam, Pseudocardium sachalinense , which feeds on phytoplankton , benthic microalgae, and detritus in coastal waters, is one of the most important marine resources in Hamanaka, Hokkaido Prefecture, Japan. We measured stable carbon and nitrogen isotope ratios (δ 13C and δ15 N) and carbon‑nitrogen (C/N) ratios of surf clam adductor muscle and stomach contents, oceanic particulate organic matter (POM), oceanic sediments, riverine POM, and soil, as well as physical and chemical parameters such as temperature, salinity, chlorophyll-a, and nutrients in Hamanaka from April through September 2015. We also examined the food sources that support the surf clam, the possible connection between wetlands and coastal waters, and the spatial and seasonal variation. Our results showed that the isotope and C/N values of surf clams and oceanic organic matter were significantly different from those of riverine organic matter, and that there were no significant differences among different sites of coastal areas. This means that land-derived organic matter is not a direct food source for the surf clam and does not affect the coastal environment. In addition, benthic microalgae and epiphytes are considered to be the major food sources for the surf clam in all sampling seasons, since they have isotope and C/N values similar to those of the surf clam. The overall results, also with reference to previous relevant studies, imply the importance of conservation of wetlands which buffer excessive inflow of land-derived organic matter that may harm surf clams and the coastal environment.

Pyrosome consumption by benthic organisms during blooms in the northeast Pacific and Gulf of Mexico.

Pyrosome consumption by benthic organisms during blooms in the northeast Pacific and Gulf of Mexico.

Clay Coating Systems for Removal of Heavy Metals for Waste Water

Algae turf scrubbers and other biological methods to purify polluted waters hold promise for simultaneously removing excess nutrients and producing a potentially valuable biomass crop. The harvested biomass can be used for fuel production, animal feed, or in some cases a direct food source. However, when applied to industrial waste waters contaminated with heavy metals such as lead, cadmium, and chromium VI the use of the biomass is limited. Thus, a system to remove heavy metals from these waters prior to biological filtration is required. In an industrial setting, several methods are applied for the removal of heavy metals including membrane filtration, electrolytic reduction, and ion-exchange reactions. Adsorption methods are particularly attractive owing to the possibility of regeneration and reuse. Halloysite nanotubes, a weathered smectite clay, have been investigated for adsorption of several heavy metals. Here we propose the use of a crosslinked Halloysite network for the adsorption of heavy metals from waste streams. A thermally reversible Diels-Alder reaction scheme is used to crosslink Halloysite nanotubes and allows for the system to be cast into multiple configurations such as coating and porous membranes with high Halloysite loadings. Halloysite nanotubes were modified with 3-(2-Furyl)propanoic acid or 11-maleimido-undecanoic acid. Mixtures of these materials were solution cast resulting in crosslinked Halloysite films and membranes. These systems were evaluated for heavy metal adsorption capacity and rate.

Tropical seascapes as feeding grounds for juvenile penaeid shrimps in southern Mozambique revealed using stable isotopes

The feeding grounds for four of the most commercially important penaeid shrimp species (Metapenaeus monoceros, M. stebbingi, Penaeus japonicus and Penaeus indicus) within the mangrove and its adjacent coastal habitats (sand flat, mud flat and seagrass meadows) were investigated at Saco and Sangala bays (Inhaca Island, Mozambique, southern-East Africa). The study used carbon and nitrogen stable isotope ratios to identify the potential food sources for the different shrimp species within each habitat. Significant differences (p < 0.05) in terms of stable isotopes were observed among potential food sources in each habitat in both Saco and Sangala bays (isotopic ratios discriminating habitats), as well as between shrimp species among the different habitats. No ontogenetic dietary shifts were found for the studied penaeid shrimp species. The mangrove habitat did not provide a direct food source for most of the species at Saco and Sangala Bays. The seagrass habitat appeared to be a primary feeding area, mainly through seagrass, sediment, polychaetes and seston. The mud and sand flat habitats contributed with less food items for the shrimp species at Saco Bay, as well as the sand flat habitat at Sangala Bay. The possibility to identify feeding grounds is a fundamental tool to assist conservation of the resources and their habitat and for applying an ecosystem approach to fishery management.

Revisiting the histological patterns of storage tissues: beyond the limits of gall-inducing taxa

Gall-inducing Aphididae may feed directly on phloem, whereas Eriophyidae and Nematoda feed on cells lining the gall chambers. We assume that a variation in structural complexity will occur within galls induced by each taxon, and that the complexity of the galls could be related to the types of storage tissue they have. Histological, histometric, and histochemical analyses were used to compare six gall systems with different levels of complexity. Such levels are not taxon-related, even though eriophyid galls are usually simpler than nematode and aphid galls. The histological features of galls allowed the classification of storage tissues into three types: typical nutritive tissues (TNT), common storage tissues (CST), and nutritive-like tissues (NLT). The TNT and NLT have cells with dense cytoplasm and a prominent nucleus. The CST cells are vacuolated, and may store starch and other energy-rich molecules, as do the NLT cells. In contrast to NLT or CST, the TNT serves as a direct food source for gall inducers, and it is present in nematode and some eriophyid galls. NLTs may be present in some aphid galls, but are not the direct feeding site. The CST occurs on galls of all three inducing taxa.

Bacteria as food in aquaculture: do they make a difference?

AbstractBacterioplankton is an important component of marine as well as fresh waters and accounts for a large fraction of the production of particulate matter in those ecosystems. The concept of bacteria as providers of essential nutrients in aquatic food webs has been raised most recently in relation to the utilization of bacteria as a food source in aquaculture food chains. This article represents a comprehensive review on the potential role of bacteria as a direct food source for aquaculture organisms. After studying shortly the analytical tools that can be applied to determine the uptake and assimilation of bacteria by higher trophic levels, it describes the bacterial loads that are found in closed and open aquaculture systems and elaborates on the composition of bacteria from a nutritional point of view. Next this study elaborates in more detail on the role of bacteria as food for the zooplankton groups used as live food in aquaculture hatcheries and for various groups of aquaculture target organisms, such as fish, crustaceans and especially bivalves. This includes an assessment of the specific uptake mechanisms of the different taxonomic groups of interest in relation to their efficiency to ingest bacteria. Finally, future research lines are suggested to elucidate the nutritional impact of the bacterial community in aquaculture systems and how to steer this in order to optimize the production.

Analysis of the trophic role of Mediterranean seagrasses in marine coastal ecosystems: a review

Abstract Seagrasses form high-productivity coastal ecosystems, providing habitats for many organisms, including species of commercial value. They play a significant role as a direct food source for herbivores and also enter detrital food webs. In this review, the trophic ecology of Mediterranean seagrass ecosystems is revised, with major emphasis on Posidonia oceanica, the most extensively studied seagrass. The major topics are the role of herbivory and detritus, the contribution to littoral fish production, exportation to other ecosystems and the seagrass role as a vector of anthropogenic nutrients into food webs. Topics are discussed by analysing both conventional knowledge and new insights derived from the application of carbon and nitrogen stable isotope analysis. In conclusion, perspectives for future research are highlighted, with particular emphasis on areas demanding further study and on the effects of seagrass decline on trophic organisation in coastal environments.

A Hierarchical Analysis of Habitat Selection by Raccoons in Northern Indiana

Abstract: Although numerous studies have examined habitat use by raccoons (Procyon lotor), information regarding seasonal habitat selection related to resource availability in agricultural landscapes is lacking for this species. Additionally, few studies using radiotelemetry have investigated habitat selection at multiple spatial scales or core‐use areas by raccoons. We examined seasonal habitat selection of 55 (31 M, 24 F) adult raccoons at 3 hierarchical orders defined by the movement behavior of this species (second‐order home range, second‐order core‐use area, and third‐order home range) in northern Indiana, USA, from May 2003 to June 2005. Using compositional analysis, we assessed whether habitat selection differed from random and ranked habitat types in order of selection during the crop growing period (season 1) and corn maturation period (season 2), which represented substantial shifts in resource availability to raccoons. Habitat rankings differed across hierarchical orders, between seasons within hierarchical orders, and between sexes within seasons; however, seasonal and intersexual patterns of habitat selection were not consistent across hierarchical orders of spatial scale. When nonrandom utilization was detected, both sexes consistently selected forest cover over other available habitats. Seasonal differences in habitat selection were most evident at the core‐area scale, where raccoon selection of agricultural lands was highest during the maturation season when corn was available as a direct food source. Habitat use did not differ from availability for either sex in either season at the third‐order scale. The selection of forest cover across both seasons and all spatial orders suggested that raccoon distribution and abundance in fragmented landscapes is likely dependent on the availability and distribution of forest cover, or habitats associated with forest (i.e., water), within the landscape. The lack of consistency in habitat selection across hierarchical scales further exemplifies the need to examine multiple biological scales in habitat‐selection studies.

Diatom fatty acid biomarkers indicate recent growth rates in Antarctic krill

We investigated the relationship between nutritional condition (levels of specific fatty acids) and growth increment (percentage growth per intermoult period, percentage IMP−1) for Antarctic krill (Euphausia superba) collected from the vicinity of South Georgia in the austral summer 2002. There were correlations between percentage IMP21 and the concentration (gram : gram dry weight) of the diatom biomarker fatty acids, 16 : 4(n−1) and 20 : 5(n−3) in tissues of individual krill, suggesting that the abundance of diatoms in the environment of the krill in the intermoult period prior to moulting was a key determinant of change in body length, a proxy for growth. This substantiates the view that diatoms are crucial for supporting high growth rates of krill, either as a direct food source or, indirectly, by enhancing production of microzooplankton and mesozooplankton based food webs.

A new method to purify hepatic CYP1A of Prochilodus scrofa, a Brazilian freshwater fish

Cytochromes P450 constitute a superfamily of the phase I enzymes whose primary task is the detoxification of both endogenous and xenobiotic compounds. Fish, among non-mammalian species, have received great interest because they are a direct food source for humans as well as conveyors of toxic chemicals to human beings. The aim of the present study was the purification of the hepatic isoform of CYP1A in Prochilodus scrofa (Prochilodontidae), a Brazilian fish, using only one chromatographic step. The purification of CYP1A was done by Reverse Phase HPLC on a C18 column. Purified CYP1A was characterized with respect to electrophoretic, immunochemical and biocatalyst properties. CYP1A fractions produced a single uniform band on SDS-PAGE with an apparent molecular mass of 58 kDa. Purified CYP1A of P. scrofa showed strong cross-reactivity with antibodies directed against CYP1A from trout. The fraction was also encapsulated in two different reconstituted systems; one composed of neutral lipids and another of negatively charged lipids. In both of them, we could detect EROD activity but not PROD activity, which confirms that the CYP1A was purified with all its enzyme activity. There was an increase of activity when CYP1A and NADPH cytochrome P450 (CYP) reductase were encapsulated in negatively charged lipids, which confirms that the charge of lipid is essential to CYP1A activity. All these characteristics strongly suggest that this new procedure is efficient for purifying hepatic CYP1A from P. scrofa, showing that the CYP1A isoform of this fish has a highly conserved protein region.

Leaf litter colonization by invertebrates in the littoral zone of a small oligotrophic lake

The colonization of deciduous leaf litter by aquatic invertebrates was studied at Scott Lake in Algonquin Park, Ontario, Canada. Deciduous leaf packs were colonized after only 2 days submergence. The invertebrate community was dominated by chironomids (25–94% depending on sampling period), and to a lesser extent by oligochaetes, turbellarians, and mayflies. Collectors, such as the chironomids Dicrotendipes, Pseudochironomus, Paratanytarsus and Parakiefferiella were the dominant functional-feeding group suggesting that leaf litter is being used as habitat rather than a direct food source. Deciduous leaf litter lost a substantial amount of weight, due to leaching, after only 48 h submergence. Fall-shed beech (Fagus grandifolia) leaves decomposed more rapidly than fall-shed sugar maple (Acer saccharum) leaves with daily processing coefficients (k), determined using an exponential decay model, of 0.0058 and 0.0039, respectively. Conversely, conditioned maple leaves, defined as leaves remaining on the ground over winter, were processed faster than conditioned beech leaves, with coefficients of 0.0042 and 0.0014, respectively. It is speculated that inhibitory compounds have been leached from the maple leaves, allowing for faster leaf processing.

The reef cave dwelling ultraconservative coralline demospongeAstrosclera willeyana Lister 1900 from the Indo-Pacific

The reef cave dwelling ultraconservative coralline demospongeAstrosclera willeyana Lister 1900 from the Indo-Pacific

Pitcher‐Plant Midges and Mosquitoes: A Processing Chain Commensalism

Larvae of the midge Metriocnemus knabi and of the mosquito Wyeomyia smithii are found only inside the water—filled leaves of the carnivorous pitcher plant, Sarracenia purpurea, where they feed on decaying invertebrate carcasses. I examined the interaction between the two species in a natural population in western Newfoundland, Canada. Experimental manipulations of rates of prey capture by pitcher—plant leaves indicated that both insect species are limited by carcass supply. However, the interaction between them is commensal rather than competitive. Midge growth was unaffected by experimental quadrupling of mosquito density in otherwise unmanipulated leaves. Mosquito growth, on the other hand, increased with midge density in both natural leaves and artificial leaf microcosms. This interaction is an example of a processing chain commensalism. Although both species feed on carcass material, they use it in different stages of decay; midges feed by chewing on solid material, while mosquitoes filter—feed on particles derived from the decaying matter. Consumption of particles by mosquitoes does not affect resource availability for midges, but feeding by midges does influence particle availability. In artificial leaf microcosms, high bacterial densities occurred sooner in artificial leaves with midges present than in identical leaves without them. Bacteria are a direct food source for mosquitoes, and high bacterial densities also indicate that other organic material is being comminuted, providing particles for mosquitoes and surface area for bacterial growth. Although midges remove some of the carcass resource that also limits mosquitoes, their net effect on mosquitoes in positive because they accelerate conversion of the remaining resource to particles.

Potential role of large oceanic diatoms in new primary production

Very large phytoplankton species >50 μm in size, particularly diatoms, generally are found in background numbers throughout the euphotic zone of oceanic waters. Yet, when responding to episodic injections of new nutrients across the nutricline at the base of the euphotic zone these phototrophs may make a disproportionately large contribution to new primary production. To test this concept, we isolated a group of large diatoms from the Sargasso Sea and found that the specific growth rate of several of these species in culture was great enough at the ≈2% light level in oligotrophic waters to meet the requirements of several hypothetical scenarios in which annual rates of new production from the sum of one or more episodic blooms were equal to contemporary estimates. Two of the fast-growing species, Stephanopyxis palmeriana (Greville) Grunow and Pseudoguinardia recta von Stosch, formed giant flocculant masses while growing. Such masses could sink rapidly out of the euphotic zone or be a direct food source for invertebrates or fish higher up the food chain. Not only would a short, simple trophic system with low losses result, but the events would virtually be impossible to observe with conventional sampling.

A Seaweed Buffet

Research Article| March 01 1991 A Seaweed Buffet Christine D. Maxwell Christine D. Maxwell Search for other works by this author on: This Site PubMed Google Scholar The American Biology Teacher (1991) 53 (3): 159–161. https://doi.org/10.2307/4449250 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Christine D. Maxwell; A Seaweed Buffet. The American Biology Teacher 1 March 1991; 53 (3): 159–161. doi: https://doi.org/10.2307/4449250 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentThe American Biology Teacher Search This content is only available via PDF. Copyright 1990 National Association of Biology Teachers Article PDF first page preview Close Modal You do not currently have access to this content.

The Use of Decapsulated Cysts of the Brine Shrimp Artemia as Direct Food for Carp Cyprinus carpio L. Larvae

AbstractDecapsulated Arremia cysts have been evaluated as a direct food source for larvae of the carp Cyprinus carpio L. All decapsulated cyst diets gave excellent survival of carp larvae during the first two weeks of culturing. Unlike traditionally brine‐stored decapsulated cysts, dried Artemia embryos provided growth results comparable to those obtained with freshly hatched Artemia nauplii. Furthermore, except for Artemia embryos that lost their hatchability after long‐term storage in air, several other inactivation treatments, simulating improper harvesting and processing of cysts, did not produce a significant decrease in the nutritional quality of the decapsulated cysts.Using decapsulated cysts 89 a direct food source for carp larvae, instead of nauplii, the quantity of cysts needed can be reduced by about 25% to 35% after one and two weeks of culturing, respectively. Moreover, the use of decapsulated cysts advances the possible commercialition of poor‐hatching and less expensive cyst products for culture of carp larvae.

Fish communities of interacting shallow-water habitats in tropical oceanic regions

Coral reefs occur in a variety of situations in the Atlantic, Pacific and lndian Oceans, which involve great differences in the degree of isolation from surrounding shallow-water environments, e.g. seagrass beds, mangroves and unvegetated sediments. Mangroves and seagrass beds appear to offer attractive habitat for fishes including species commonly found on reefs especially for settling postlarvae and developing juveniles. These habitats probably intercept large numbers of recruits, and may offer some advantages over coral reefs for early survival of young juveniles. They may act as accumulators of excess recruits, which could tend to smooth out the temporal patchiness of recruits available to reefs directly from the plankton. However, there is no clear evidence that, in general, reefs situated favorably to the shallow-water, vegetated habitats experience enhancement of these early life stages, by comparison with more remote reefs There are a few demonstrated mechanisms for movement of plant and animal material (alive, dead or reprocessed) between these shallow-water habitats. including recycling of reef organic production through an adjacent habitat and back to the reef. The absolute values of such fluxes assimilated by (or returned to) the reef may be small, but the means by which the material is exchanged may be particularly suitable to enhance fish populations. Relative trophic patterns among the various shallow-water, demenal habitats and among the oceans of the world are not entirely clear. This is partly because quantitative fish community studies and trophic studies in seagrass and mangrove habitats are inadequate. Among fish, carnivores appear to dominate in all habitats in almost all situations; usually benthic invertebrates are the major prey group. In a few reported situations, primarily in the Pacific, planktivory appears to be the dominant feeding mode. Algivory is important in all situations, but almost never dominant, and its importance varies widely within (as well as between] oceans and types of situations. I t may be most significant on the open coasts of some isolated islands and atolls. Seagrass is a minor direct food source in all oceans and is best documented in the Atlantic. If important linkages occur among the shallow-water, adjacent, tropical habitats, they most likely involve fish recruitment and/or trophic processes involving invertebrates. Both are little-known subjects in these environments, that will require additional, focused research to clarify the nature and magnitude of any interactions that influence marine resources.

THE DIGESTION OF WOOD BY INSECTS AND THE SUPPOSED ROLE OF MICRO‐ORGANISMS

Summary The relation between certain insects and the intracellular micro‐organisms they harbour is obscure and cannot be described as symbiotic for the following reasons: Sterile mycetomes are known to occur in some species closely related to others with heavily infected mycetomes. Defloration experiments have been carried out successfully without any harmful effect to the host insect. Intracellular micro‐organisms in xylophagous insects cannot be considered as playing an important role in the digestion of wood for the following reasons: In weevils with wood‐eating habits which have intracellular micro‐organisms, the latter only pass into the lumen of the gut of their host during the adult stage when the insect is not feeding on wood. Some wood‐eating species of insects harbour intracellular micro‐organisms, while closely related species with similar feeding habits are free from these. The intracellular micro‐organisms of some wood‐eating forms have been cultivated in vitro and found to be unable to break down cellulose. The relatively high content in nitrogenous substances of different kinds of wood, and the general occurrence of proteolytic enzymes in insects, make the assumption that intracellular micro‐organisms fix atmospheric nitrogen for the use of their host superfluous. The extracellular intestinal micro‐organisms of certain lamellicorn larvae and of some termites play no role in breaking down cellulose for the use of their host. They are utilised as a direct food source. Such insects are therefore better referred to as micro‐organism‐feeders. True wood‐eating insects derive the necessary carbohydrates from the wood they live on through the activity of their own enzymes. The enzyme complex in such insects has been found to vary from species to species. The carbohydrate components of wood vary in quantity in different kinds of wood. Some true wood‐eating forms depend upon starch and soluble sugars for their source of carbohydrates. Such insects have no cellulase and can consequently only live in kinds of wood comparatively rich in starch and sugars. Other true wood‐eating forms secrete cellulase and are therefore able to live in kinds of wood comparatively poor in starch and soluble sugars. The occurrence of hemicellulase has been demonstrated only in a very few cases and the value of the hemicelluloses as food for wood‐eating insects has not been thoroughly investigated.