Description of the digestive tract and feeding habits of the king angelfish and the Cortes angelfish

Morphologically, the digestive tracts of the king angelfish Holacunthus passer and the Cortes angelfish Pomacanthus zonipectus are similar, yet the king angelfish intestine is almost 30% longer than that of the Cortes angelfish. Both pomacanthids have a small mouth with villiform teeth, a short oesophagus, a well-defined stomach, and a terminal sac at the end of the digestive tract. The terminal sac, the acid pH in the stomach, and the long intestine may facilitate efficient use of seaweed nutrients. Stomach contents were analysed to determine diets and interspecific overlap. Seventy-one species were found in the stomachs of the king angelfish and 53 in the stomachs of the Cortes angelfish. Because of the wide range of species in their diets, both angelfish must be regarded as omnivorous. The most frequent foods were seaweed and sponges, but for the king angelfish, crustaceans were also important. A cluster analysis was done to determine whether the diets of these fish were similar by sex, size, or season. No similarities were found. Dietary overlap is high in relation to other pomacanthids.     

Seasonal Variation in the Diets of Bluefish, Pomatomus saltatrix (Pomatomidae) and Striped Weakfish, Cynoscion guatucupa (Sciaenidae) in Southern Brazil: Implications of Food Partitioning

The stomach contents of 516 Pomatomus saltatrix and 506 Cynoscion guatucupa from southern Brazil were examined. Both species preyed primarily upon teleosts and crustaceans and occasionally squid. Seasonal variation in the diet was related to prey availability in the area, confirming the opportunistic feeding behaviour of both species. During the summer, P. saltatrix preyed upon four prey species (Loligo sanpaulensis, Artemesia longinaris, Mullus argentinae and Paralonchurus brasiliensis), whereas in the autumn and winter Engraulis anchoita was the predominant prey. C. guatucupa similarly preyed upon A. longinaris and P. brasiliensis during the summer, with juvenile C. guatucupa and E. anchoita also consumed. The latter species was an important dietary constituent during other seasons, as were A. longinaris (autumn), Umbrina canosai (winter), Trachurus latami and euphausids (spring). Although P. saltatrix had a broader diet than C. guatucupa during the summer, the latter species had a broader diet overall. Diet breadths were lower from autumn to spring, due to the predominance of E. anchoita in the diet of both species. This restricted diet resulted in significant intra- and inter-specific diet overlap during the winter but, because of the seasonal abundance of E. anchoita, the high levels of diet overlap do not necessarily indicate competition.     

Feeding habits the Pacific cod <Emphasis Type="Italic">Gadus macrocephalus</Emphasis> in oceanic waters of the Northern Kuril Islands and Southeast Kamchatka

This study examines the feeding habits of the Pacific cod Gadus macrocephalus in waters off the eastern coast of the northern Kuril Islands and southern Kamchatka. In November–December 1996, the cod primarily consumed fish, which made up 47.6% of the total food mass. The proportion of cephalopods, fishery offal discarded from fishing vessels, and decapods did not exceed 18.5, 17.4, and 12.2%, respectively. Among fishes, the main prey item of the cod was atka mackerel (15.4%); among cephalopods, octopus (16.8%); among fishery offal, heads of atka mackerel (14.2%); and among decapods, majid crabs (6.4%). The rather low percentage of walleye pollock (7.3%) in the cod diet was due to the decline of the east-Kamchatka walleye pollock stock.     

Evidence of food items used by <Emphasis Type=Italic>Fulmarus glacialoides</Emphasis> (Smith 1840) (Procellariiformes: Procellariidae) in Southern Brazil

Monitoring trips were conducted along the coast of the state of Rio Grande do Sul, Brazil from July 1997 to July 1998 to contribute toward knowledge on the feeding habits of Fulmarus glacialoides during migration. Five hundred and sixty two carcasses of F. glacialoides were found, 42 of which were in adequate conditions for collection and subsequent stomach content analysis. All stomach revealed the remains of cephalopods. The following were identified from the 60 lower beaks of cephalopods found: Sepidae, Histioteuthis sp., Discoteuthis sp., Chiroteuthis sp., Mesonychoteuthis hamiltoni, Lycoteuthis sp., Lycoteuthis lorigera, Ancistrocheirus lesueuri, Alluroteuthis antarctica, Loligo plei and Argonauta nodosa. Histioteuthis sp. was found in 70% of stomachs analyzed, with a mean biomass of 53 g. Fish were identified through otoliths and were found in the stomach contents of two specimens. Elytra from insects were found in the contents of eight stomachs, at least 20 of which were coleopterans. A Belostomatidae was found in the contents of one stomach.     

Host range of the European leaf sheath mining midge,Lasioptera donacis Coutin (Diptera: Cecidomyiidae), a biological control of giant reed,Arundo donax L.

The fundamental host range of the arundo leafminer, Lasioptera donacis a candidate agent for the invasive weed, Arundo donax was evaluated. L. donacis collects and inserts spores of a saprophytic fungus, Arthrinium arundinis, during oviposition. Larvae feed and develop in the decomposing leaf sheath channel tissue. Thirty-six closely related and economic grass species along with several key habitat associates were evaluated in no-choice tests. L. donacis and its associated saprophyte completed development only on A. donax, in concurrence with published reports from its native range in Mediterranean Europe. The arundo leafminer feeding leads to premature defoliation, constituting a different mode of attack on the host plant as compared to two previously released insects, the arundo wasp and arundo scale, which feed on shoot tips and rhizomes, respectively. Defoliation of A. donax is expected to increase light penetration into stands of A. donax which increases visibility for law enforcement, reduces the survival of cattle fever ticks, and enhance recovery of the native riparian vegetation along the Rio Grande and other habitats where this weed is invasive.     

Heavy Metal Distribution in Open Canals and Drains in the Upper Rio Grande Basin

The inclusion of reclaimed effluents for irrigated agriculture may allow communities along the U.S.-Mexico border to use water resources more efficiently and reduce urban costs of wastewater treatment. However, metal inflow from industry and urbanization may threaten food safety. This study examines metal concentrations in sediments from open canal systems charged with flow from the Rio Grande and from effluents discharged from border communities. At the surface of canal beds, sediments were collected from six canal segments that began at the fringe of the El Paso/Juarez metroplex to rural areas downstream, and ranged from 9 to 24?km in length. Sediments were analyzed for Cd, Co, Cr, Cu, Ni, Pb, and Zn. These metals rarely exceeded 20?mg kg^?1. Drainage and effluent conveyance increased the variability of metal concentrations in sediments. Geostatistical models did not significantly account for spatial variability of metals, except in Mexico. This may implicate multiple rather than single inflow sources of metals. Peaks in metal concentrations often coincided with growing rural communities. However, most metal concentrations were within conventional global ranges and were not at levels high enough to threaten food safety. Future sampling strategies will require reduced sampling intervals from 1 to <0.13?km.     

Detection of <Emphasis Type=Italic>Giardia,Entamoeba,</Emphasis> and <Emphasis Type=Italic>Cryptosporidium</Emphasis> in unprocessed food items from northern India

This study was conducted to evaluate the load of three food- and water-borne parasites, namely, Giardia, Entamoeba, and Cryptosporidium on food items that are consumed either raw or in an unprocessed state in the northern parts of India. A two-step diagnostic method was employed to assess the presence of Giardia and Cryptosporidium, the immunofluorescence assay (IFA) combined with the polymerase chain reactiion (PCR assay), whereas a Tech lab diagnostic kit in combination with PCR assay was used for accurate detection of Entamoeba histolytica in the samples. The methods for isolation and enrichment of cysts/oocysts from the various food items were tested and discussed here. Our results showed that the overall spectrum of incidence of the three parasites on food items in decreasing order were Giardia > Entamoeba > Cryptosporidium. When data were subjected to the chi-square test, the prevalence of all three parasites was found to be independent of the food items. To determine whether the presence of two types of parasites in a food item is uniform, a Poisson distribution test was conducted. On comparing the intensity of occurrence of the different parasites in various food items, it was observed that the occurrence of Giardia and Entamoeba was not of the same order at 5% level of significance only in case of samples of raw meat and milk. This confirmed that a high number of raw or unpasteurized milk and meat samples are more likely to be contaminated with Giardia than with Entamoeba. Therefore, our observations point to the unhygienic practices of food handlers being a major contributor in the transmission of parasites to unprocessed food products.     

Maternal Milk Concentration of Zinc,Iron, Selenium,and Iodine and Its Relationship to Dietary Intakes

The dietary intake of zinc (Zn), iron (Fe), selenium (Se), and iodine (I) of 31 lactating Mexican–American women attending the Hidalgo County WIC program in Rio Grande Valley (RGV), Texas was estimated from 24-h dietary recall interviews. Milk samples were obtained from lactating mothers who had infants 3 months of age and younger. Milk samples were collected in two visits to assess change in breast milk composition after 1–3 months postpartum: group A—after 30–45 days and group B—75–90 days. Dietary intakes indicated that the study participants had significantly inadequate percent energy intakes than the DRI (Dietary Recommended Intakes) percent recommended kilocalorie values but protein intakes were substantially higher than the percent recommended values. The estimated percent Zn, Fe, Se, and I intakes were also significantly lower than the DRI percent recommended values. The lactating mothers consumed significantly less Zn, Se, and I when compared to the Recommended Dietary Allowances (RDA) even though Fe intake was higher than the RDA value. Breast milk concentration of Zn, Fe, and Se were in agreement within the range of representative values for Constituents of Human Milk but I has significantly less concentration than the representative value. There was no statistically significant correlation observed between dietary intake and milk concentration of Zn, Fe, Se, and I. This study compares the estimated dietary intake of zinc, iron, selenium, and iodine to the concentration of these trace elements in the maternal milk of lactating women of Mexican–American heritage who attend the Rio Grande Valley WIC clinic.     

Aspects of the feeding habits and reproductive biology of the Ghana mole-rat Cryptomys zechi (Rodentia, Bathyergidae)

The feeding habits and reproductive biology of the Ghana mole‐rat, Cryptomys zechi (Matchie), were studied in a Guinea savanna woodland in Ghana. Both tunnel contents and stomach content analysis indicated that bulbs and tubers constituted the commonest and most preferred food items, although some animal food materials were also consumed. Five plant species, Urgenia altissima, Manihot utilisima, Curuligo sp., Oxalis corniculata and Archis hypogea, were the most popular plant food source. Breeding occurred during the rainy season (March–August) and was at its peak in July. There is evidence that the species is capable of producing two litters in a year. In a colony, reproduction is restricted to one female and one male. Males reached sexual maturity at a lower body weights (105 g) than females (155 g). Estimated mean litter size was 1.5 (range 1–2), the smallest among the bathergids. Available data on birth weights of three other species of social Cryptomys indicate that C. zechi has the highest birth weight, which is comparable to that of solitary bathyergids.     

Morphological variation of the digestive tract: a feeding behaviour response in a freshwater fish species

Environmental Biology of Fishes - Plasticity of resource use represents an important strategy for fish species living in unstable freshwater environments. Trophic polymorphism (i.e. variation in...     

池养大口胭脂鱼鱼种的食性

池养大口胭脂鱼鱼种的食性研究表明 ,大口胭脂鱼鱼种为浮游动物尺寸选择性鱼类 ,其选食行为主要受鱼体及水体中浮游动物的个体大小影响 ,与浮游动物的种类、逃跑能力、运动方式等关系不明显。并初步探讨了 3种浮游生物食性鱼类 (大口胭脂鱼、鲢、鳙 )的食物关系。     

Morphology and ultrastructure of a specialized bacterial pouch in the digestive tract of Tetraponera ants (Formicidae, Pseudomyrmecinae)

The digestive tract in workers of some species of the pseudomyrmecine ant genus Tetraponera is characterized by a conspicuous pear-shaped diverticulum at the transition between the midgut and the intestine, that so far has not been found in any other ant species. As this organ is filled with a mass of bacteria, we propose to designate it as a bacterial pouch. Its distal wall is formed by a thin ectodermal epithelium, through which tens of tracheal branches penetrate into the bacterial mass that fills the pouch lumen. The proximal wall, in contrast, is formed by a cylindrical epithelium with a conspicuous microvillar differentiation of the apical cell membrane, but without a cuticular lining. The contact region between both epithelia occurs as a complex fold surrounding the pouch like a belt. The Malpighian tubules open into the pouch through the cylindrical epithelium adjacent to the belt fold. The functional significance of the bacterial pouch remains unknown, although the abundant presence of bacteria may indicate a symbiotic function. The conspicuous tracheolar supply illustrates the metabolic activity in the pouch, while the microvillar differentiation of the cylindrical epithelium may be interpreted in the uptake of metabolites from the pouch lumen.     

Characterization of tetranucleotide microsatellites for Rio Grande cutthroat trout and rainbow trout,and their cross‐amplification in other cutthroat trout subspecies

We describe the isolation and characterization of 12 tetranucleotide microsatellites for Rio Grande cutthroat trout (Oncorhynchus clarkii virginalis) and rainbow trout (Oncorhynchus mykiss), and subsequently investigate their performance in Colorado River cutthroat trout (Oncorhynchus clarkii pleuriticus), greenback cutthroat trout (Oncorhynchus clarkii stomias) and Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri). All 12 loci are polymorphic in all subspecies of O. clarkii examined.     

Food and feeding habits of four species of juvenile mullet (Mugilidae) in a tidal lagoon in Ghana

Juvenile mugilid fishes, Liza falcipinnis, L. dumerilii, Mugil bananensis and M. curema , which enter the Elmina Lagoon in the Cape Coast District of Ghana, have a similar diet comprising mainly bacteria, diatoms, blue-green/green algae, protozoans, detritus and particulate organic matter. No seasonal changes in the diet and feeding activity were observed. The relative gut length (intestine to standard length ratio) and diet showed no significant changes with size of fish in all the species. All four species were diurnal feeders, but their peak feeding times differed. Interspecific competition for food was possibly limited by species preferences for substrate particles of particular size range and differences in feeding chronology.     

Morphological adaptation of the digestive tract in relation to feeding ecology of raptors

The study examines some aspects of gross morphology in Falconiformes and Strigiformes. It is hypothesized that, in predatory birds, hunting strategy might influence the relative size of skeletal musculature and length of the digestive tract. Falconiform species were categorized as either 'attackers' or 'searchers' depending on the degree to which active, powered pursuit is required for prey capture. Attacking species feed predominantly on avian prey, requiring extreme agility, speed and acceleration for prey capture. Searchers feed largely on relatively slow-moving mammals and carrion. Comparisons between species of attackers and searchers showed that the former had heavier pectoral muscle mass, larger areas for flight muscle attachment and higher linearized wing loadings. Strigiformes had a pectoral muscle mass only half the size of that of attacking Falconiformes and had a correspondingly smaller sternum area. A skeletal body-size measure was determined to enable calculation of intestine length independent of body-size and shape differences. Attacking species have a small intestine which is 20–30% shorter than would be predicted on the basis of body-size and 50% shorter than found in searchers of equivalent body-size. Strigiformes that locate prey by active flight also have intestinal tracts shorter than expected. The likely effects of intestine length on digestive efficiency and food utilization are discussed and it is suggested that, in predatory birds, some species have evolved alimentary tracts that are shorter than necessary for maximum digestive efficiency in order to enhance prey capture.     

Food and feeding habits of Mirogrex fingerlings in Lake Kinneret (Israel)

The food composition of the fingerlings (13–41 mm TL) of Mirogrex terraesanctae terraesanctae was studied on specimen collected at four stations in Lake Kinneret. The fingerling feed mostly on pelagic zooplankters and zoobenthic forms whereas algae were found in the intestines in low biomass. The number of zooplankton organisms in the guts of the fingerling that were sampled during June–August was higher by 234% than in fingerlings that were sampled during March–April. The role of sardines fry in the Kinneret ecosystem is discussed.     

Morphology and histology of the digestive tract of Nautilus pompilius and Nautilus macromphalus (Cephalopoda, Tetrabranchiata)

 This study presents histological and scanning electron microscopical findings on the structural differentiation, and the nervous and vascular supply of the digestive tracts of Nautilus pompilius and N. macromphalus, including the foregut, stomach, vestibulum, caecum, midgut and rectum. The stereoscopic reconstruction of the vestibulocaecal complex gives an idea how the digestive cycle between the stomach, vestibulum, caecum and proximal midgut could possibly proceed. All parts of the digestive tract are covered luminally by a columnar epithelium which contains numerous goblet cells. The epithelium is ciliated in the vestibulum, caecum, proximal midgut and the longitudinal groove of the rectum. On this lamina epithelialis mucosae borders the lamina propria mucosae, which consists of connective tissue and some muscle cells. In the stomach it is differentiated, forming a special bolster-like layer. The lamina propria mucosae is followed by the tunica muscularis, which consists of a stratum circulare and a stratum longitudinale in the foregut, vestibulum, caecum, midgut and rectum. In the stomach, midgut and rectum, the tunica adventitia, which consists of a thin layer of connective tissue, is located between the tunica muscularis and the cuboidal tunica serosa. Accepted: 4 August 1997     

Impact of the arundo wasp,Tetramesa romana (Hymenoptera: Eurytomidae), on biomass of the invasive weed,Arundo donax (Poaceae: Arundinoideae), and on revegetation of riparian habitat along the Rio Grande in Texas

An invasive grass, Arundo donax, occupies thousands of hectares of arid riparian habitat along the Rio Grande in Texas and Mexico, and has negative impacts on national security, water resources, and riparian ecosystems. The shoot-tip-galling wasp Tetramesa romana was released in 2009 between Brownsville and Del Rio, Texas, and has dispersed over 800?km along the river channel. Plots along the river were surveyed for shoot counts of arundo and all other plant species in 2016 at seven sites in regions in which prior studies had documented a 22% decline in arundo biomass (estimated from live shoot length) from 2007 to 2014. Estimated live biomass declined a further 32% between 2014 and 2016. Native plants accounted for 86% of the 44 species encountered in plots. Individual plots averaged five plant species, and arundo was most abundant in only 9 of 21 plots. Arundo live biomass and shoot density were negatively associated with plant diversity, indicating that live arundo interferes with germination and/or survival of other plant species. The proportion of dead shoots in plots, proportion of wasp-galled shoots, and density of exit holes made by emerging adult wasps per metre live main shoot length were positively associated with plant diversity in a combined model. Regressions indicated that the effects of wasp damage measures on diversity were mediated through their effects on main shoot mortality. By reducing live arundo biomass, the arundo wasp is fostering recovery of native plant communities at riparian sites along the Rio Grande.