Anthropogenic impact of mercury accumulation in fish from the Rio Madeira and Rio Negro rivers (Amazonia)

Fish is an important concentrator of mono-methyl mercury and the main route to human contamination. We compared fish Hg bioaccumulation (within similar weight ranges) in two Amazonian river habitats during high-water seasons. The Rio Madeira has been greatly impacted by agriculture, alluvial gold extraction, and a hydroelectric reservoir, whereas the Rio Negro is much less affected by these human activities. The species at the top of the food web, Hoplias malabaricus (piscivorous; 80-668 ng Hg/g) and Cichla spp. (piscivorous; 42–747 ng Hg/g) showed the highest range of Hg concentrations. Nonpiscivorous species with comparable weight range, such as Potamorhina latior (detritivorous; 20–157 ng Hg/g) and Myleus torquatus (herbivorous; 2–182 ng Hg/g), had lower Hg concentrations. Triportheus elongatus (omnivorous; 5–350 ng Hg/g), with the lowest weight range, also showed a low range of Hg concentrations. Despite the Rio Madeira's higher sediment load as well as environmental impacts (deforestation, agriculture, hydroelectric reservoir, and alluvial gold mining) on natural Hg release, fish Hg bioaccumulation was no different between the two river habitats for nonpiscivorous species. In this small observational study only the species at the top of the food web (M. torquatus, Cichla spp, T. elongatus) showed higher mean Hg concentrations in the Rio Madeira than the dominantly wilderness habitat of the Rio Negro.     

The diet and growth of 0-group dace, Leuciscus leuciscus (L.), and roach, Rutilus rutilus (L.), in a lowland river

The diets of 0-group dace and roach in the Lower Welsh Dee were studied by stomach contents analysis of seasonal and diel samples. During development, dace preyed on a sequence of food types, initially being mainly carnivorous then becoming nocturnally carnivorous and diurnally omnivorous. Roach showed a similar pattern, although after the first two months of life they were more herbivorous/detritivorous. From the variations in the diets, it is hypothesised that both species are limited by food. This receives circumstantial support from their poor observed growth. The food supply routes by which flow regulation of the River Dee could affect juvenile fish production are noted.     

Marine-freshwater transitions are associated with the evolution of dietary diversification in terapontid grunters (Teleostei: Terapontidae)

The ecological opportunities associated with transitions across the marine-freshwater interface are regarded as an important catalyst of diversification in a range of aquatic taxa. Here, we examined the role of these major habitat transitions and trophic diversification in a radiation of Australasian fishes using a new molecular phylogeny incorporating 37 Terapontidae species. A combined mitochondrial and nuclear gene analysis yielded a well-supported tree with most nodes resolved. Ancestral terapontids appear to have been euryhaline in habitat affiliation, with a single transition to freshwater environments producing all Australasian freshwater species. Mapping of terapontid feeding modes onto the molecular phylogeny-predicted carnivorous dietary habits was displayed by ancestral terapontids, which subsequently diversified into a range of additional carnivorous, omnivorous, herbivorous and detritivorous dietary modes upon transition to freshwater habitats. Comparative analyses suggested that following the freshwater invasion, the single freshwater clade has exhibited an increased rate of diversification at almost three times the background rate evident across the rest of the family. The marine-freshwater transition within Terapontidae appears to have resulted in substantial dietary radiation in freshwater environments, as well as increased lineage diversification rates relative to euryhaline-marine habitats.     

Feeding ecology of four fishes from a mangrove creek in north Queensland, Australia

The feeding ecology of four species of fish is described in terms of associations of body form, feeding structures, and stomach contents; and of seasonal variations in diet. Black bream, Acanthopagrus berda (Forskal, 1775), and the hair-finned goby, Ctenogobius criniger (Valenciennes, 1837), are predominantly carnivorous; milk-spotted toadfish, Chelonodon patoca (Hamilton-Buchanan, 1822), largely omnivorous; and bony bream, Anodontostoma chacunda (Hamilton-Buchanan, 1822), detritivorous. The results illustrate the role of a mangrove creek in the ecology of the four species of fish and show the mangrove creek provides a nursery for A. berda and C. patoca.     

Differential enzyme targeting as an evolutionary adaptation to herbivory in carnivora

Not all members of the order Carnivora are carnivorous. Some are omnivorous, and a few, such as the giant panda, Ailuropoda melanoleuca, are almost exclusively herbivorous. Although a number of adaptations to increased plant-eating are recognized within Carnivora, few have been studied at the molecular level. One molecular adaptation to diet that is spread widely across Mammalia is the differential intracellular targeting of the intermediary metabolic enzyme alanine:glyoxylate aminotransferase (AGT), which tends to be mitochondrial in carnivores, peroxisomal in herbivores, and both mitochondrial and peroxisomal in omnivores. In the present study, we have analyzed the targeting of AGT in Carnivora in relation to species' natural diets. We show not only that there has been an adaptive shift in AGT targeting from the mitochondrion toward the peroxisome as diets have shifted from being mainly carnivorous to ones that are more omnivorous and herbivorous but also that in one lineage, namely that of the giant panda, there is evidence for positive selection pressure at the molecular level on the AGT mitochondrial targeting sequence to decrease its efficiency, thereby allowing more AGT to be targeted to the peroxisomes.     

Trophic structure of the intertidal fish association in the rocky coast of Northern Chile

The trophic relationships of 13 intertidal fish species collected in northern Chile (20 degrees 18' S and 20 degrees 54' S) from July 1997 to July 1998, the stomach content analysis of 820 specimens, were investigated. The importance of the prey items was assessed by means of gravimetric and frequency of ocurrence methods, together with the Shannon-Wiener (trophic diversity) and Pianka (trophic overlap) indexes. The results allowed to recognize a fish assemblage composed of: 46% of carnivorous species, preying mainly on porcelain crabs. polichaetes and minor crustaceans: 23% of herviborous species, preying mainly on chlorophitic algae: 31% of omnivorous species. preying mainly on chlorophitic algae. Copepoda and Gastropoda. The carnivorous fishes Cheilodactylus variegatus. Helcogrammoides chilensis. Labrisomus philippii and the omnivorous Oplegnatus insignis showed euriphagic tendencies (>2.0 bits), however, the major trophic overlap (>0.90) was observed among herbivorous and omnivorous fishes. Finally, the increase of fish species towards lower latitudes and the increase of herbivory and omnivory levels in the rocky intertidal shore were analyzed.     

广州南沙十四涌潮间带大型底栖动物的功能群

大型底栖动物根据食性可分为浮游生物食者(planktophagous, Pl)、植食者(phytophagous, Ph)、肉食者(carnivorous, C)、杂食者(omnivorous, O)和碎屑食者(detritivorous, D)五个功能群。本文根据2007-2008年度和2013-2014年度在茳芏(Cyperus malaccensis)、海桑(Sonneratia caseolaris)2种生境调查获得的各4个季度的大型底栖动物数据, 分析了广州南沙十四涌潮间带大型底栖动物功能群的生境差异、季节变化和年际变化。2007-2008年度采集到26种大型底栖动物, 低于2013-2014年度的36种。无论是2007-2008年度还是2013-2014年度, 茳芏、海桑生境的大型底栖动物均以植食者的栖息密度和生物量最高, 碎屑食者的栖息密度和生物量最低。生境比较得出, 茳芏生境大型底栖动物浮游生物食者(Pl)的丰富度指数(d)、均匀度指数(J)和多样性指数(H')均高于海桑生境。年度比较得出, 在茳芏和海桑生境, 2013-2014年度浮游生物食者的丰富度指数、均匀度指数和多样性指数均高于2007-2008年度, 这是因为2013-2014年度采集到红树蚬(Gelonia coaxans)和彩虹明樱蛤(Morerlla iridescens)等, 而2007-2008年度没有采集到。     

The effects of diet and digestive cycle on the gastrointestinal tract pH values in the goldfish, Carassius auratus L., Mozambique tilapia, Oreochromis mossambicus (Peters), and channel catfish, Ictalurus punctatus (Rafinesque)

The digestive tract pH values of the teleost fish Oreochromis mossambicus, Carassius auratus and Ictalurus punctatus were determined in fish that were (1) starved, (2) fed herbivorous, omnivorous and carnivorous diets and (3) fed altered pH diets. The digestive tract pH profile was determined throughout an 8 h cycle. The herbivorous or carnivorous nature of the diet did not affect the pH values in any of the species. Significant differences in gut pH values were observed when the fish ingested diets with altered pHs. There was a difference between the starved and baseline fed values in Carassius auratus which was not observed in the other species. The pH values in the digestive tracts of the three species varied during the digestive cycle.     

Functional morphology of the gastric mills of carnivorous,omnivorous, and herbivorous land crabs

Terrestrial decapods consume a wide variety of plant and animal material. The potential adaptations of carnivorous, omnivorous, and herbivorous terrestrial crustaceans were studied by examining the functional morphology of the gastric mill. Two closely related species from each feeding preference group were examined to identify which features of the mill were due to phylogeny and which were due to adaptation. The morphology of the gastric mill matched the diet well; the gastric mills of the carnivorous species (Geograpsus grayi and Geograpsus crinipes) possessed a blunt, rounded medial tooth and flattened lateral teeth with a longitudinal grinding groove. These features make them well suited to a carnivorous diet of soft animal tissue as well as hard material, such as arthropod exoskeleton. In contrast, the mill of the herbivorous gecarcinids (Gecarcoidea natalis and Discoplax hirtipes) consisted of a medial tooth with sharp transverse ridges and lateral teeth with sharp interlocking cusps and ridges and no grinding surface. These features would efficiently shred fibrous plant material. The morphology of the mill of the omnivorous coenobitids (Coenobita perlatus and Birgus latro) was more generalized toward a mixed diet. However, the mill of B. latro was more adapted to deal with highly nutritious food items, such as nuts and heavily calcified decapods. Its mill possessed lateral teeth with extended ridges, which sat close to the calcified cardiopyloric valve to form a flattened floor. Hard items trapped in the mill would be crushed against this surface by the medial tooth. J. Morphol. 2010. © 2009 Wiley‐Liss, Inc.     

基于生物量的大型底栖动物功能摄食群结构 及生态质量评价

基于2011年5月和9月2个航次获取的生物及环境数据, 分析了渤海湾大型底栖动物的功能摄食群组成, 并首次利用以生物量构建的摄食均匀度指数(the feeding evenness index, bj_FD)和多元AZTI海洋生物指数(multivariate-biomass AZTI marine biotic index, M-bAMBI)对渤海湾生态质量进行评价。结果表明, 渤海湾大型底栖动物功能群由4类组成, 分别是肉食者、碎屑食者、浮游生物食者和杂食者, 未发现植食者。2个航次均以浮游生物食者和杂食者的生物量最高, 碎屑食者最低。聚类分析结果表明海河口内大型底栖动物群落功能摄食群组成与其他区域明显不同。两个航次均以海河口的重金属潜在生态风险指数值(risk index, RI)较低, 且5月航次该指数沿河口向外有明显的空间分布梯度。bj_FD平均值为0.28, 指示研究区大部分区域生态质量较差, 其中低值区集中在海河口、北塘口及其附近海域, 与风险指数值的低值区基本吻合。BEST分析表明温度、盐度、重金属及营养盐等是影响bj_FD变化的主要环境因子。与M-bAMBI相比, bj_FD对海河口及北塘口较差的环境质量状况更为敏感。总体上, bj_FD适用于评价渤海湾的生态质量。     

Metal (Fe, Zn, Cu, Pb and Cd) concentration patterns in components of a macrophyte-based coastal lagoon ecosystem

Information on the metal biological fate in macrophyte-based coastal lagoons is provided; this information can contribute to the assessment of the environmental effects of metal pollution and to the development of predictive models for rational management of coastal lagoons. Iron, Zn, Cu, Pb and Cd concentrations in the dominant invertebrate and fish species of Monolimni Lagoon, Mediterranean Sea, as well as in potential major sources for metal accumulation in these animals (water, sediments, angiosperms, seaweeds), were measured. Principal Component Analysis (PCA) was conducted using metal concentrations in invertebrates and fishes. All five metal concentrations loaded significantly on the first PCA axis; however, Zn and Cu loadings were less significant than Cd and even less than Fe and Pb ones. The samples of deposit-feeding invertebrates were separated from those of the rest of the organisms (browsing, herbivorous and carnivorous invertebrates, carnivorous gobies and muscle tissues of detritivorous mullets) along the first PCA axis. Deposit-feeding invertebrates displayed the highest Fe and Pb contents, and in general, the highest or comparatively high Cd, Zn and Cu ones. Carnivorous gobies showed comparatively high Zn contents and carnivorous shrimps the highest Cu ones, while muscle tissues of detritivorous mullets had low metal loads. In addition, there was no essential increase in metal concentrations corresponding to the increasing trophic level (autotrophs, to herbivores, to carnivores). Our findings suggest that (a) the variability in Fe, Pb and Cd contents in invertebrates and gobies depends at least to some extent on interspecific differences in feeding habits—deposit feeders accumulated the highest metal amounts probably due to high rates of uptake from sediments, (b) the variability in Zn and Cu concentrations in these organisms depends also on other interspecific differences apart from those in feeding habits, (c) metal accumulation in mullet muscle tissues does not depend markedly on feeding habits and (d) the trophic transfer of macrophyte-bound metals to the coastal lagoon food web is of relatively minor importance.     

Study of the haemoglobin content of a single erythrocyte (M index) in various cultured fish species

Investigations of the erythrocyte count, haemoglobin content and M index of 7 fish species were performed under equivalent environmental conditions in the same period of the year. The species were: bighead Hypophthalmichthys nobilis (Richardson), carp Cyprinus carpio L., silver carp Hypophthalmichthys molitrix (Val.), grass carp Ctenopharyngodon idella (Val.), sheat-fish Silurus glanis L. , pike Esox Indus L., pike-perch Lucioperca lucioperca (L.). Bighead and carp are carnivorous and omnivorous, silver carp and grass carp are herbivorous and sheat-fish, pike and pike-perch are predatory. Significant differences were demonstrable between M values of fish living on different type of food, where the M index is: It is concluded that M index values are useful as one parameter differentiating between fish with distinctly different food habits.     

Carbohydrase activity in the digestive system of some teleost fishes.

The activity of carbohydrases in Puntius sophore (Ham.), Channa gachua (Ham.) and Cirrhinus mrigala (Ham.) has been studied. The carbohydrases have been found in the stomach, intestinal bulb, intestine, pyloric caeca and the hepato-pancreas. The hepatopancreas is the main site of production of these enzymes and it is in this organ and the intestine that their activity is highest. Their pH optimum lies between 5.4 and 6.4. The enzyme equipment in the teleost is adapted to their respective food and feeding habits both qualitatively and quantitatively. In Puntius (omnivorous) and Cirrhinus (herbivorous) all three carbohydrases, namely amylase (EC 3.2.1.1.), sucrase (EC 3.2.1.26.) and raffinase, while in Channa (carnivorous) only amylase and sucrase have been found to be active. In Cirrhinus mrigala, which is predominantly a herbivorous species, the concentration of carbohydrases is higher than those in the other two fishes.     

Testing hypotheses of convergence with multivariate data: morphological and functional convergence among herbivorous lizards

Abstract Despite its importance to evolutionary theory, convergence remains an understudied phenomenon and is usually investigated using qualitative data. This paper advances a new, multidimensional view of convergence. Three patterns indicative of convergence are discussed, and techniques to discover and test convergent patterns in a quantitative framework are developed. These concepts and methods are applied to a dataset of digitized coordinates on 1554 lizard skulls and 1292 lower jaws to test hypotheses of convergence among herbivorous lizards. Encompassing seven independent acquisitions of herbivory, this lizard sample provides an ideal natural experiment for exploring ideas of convergence among different systems (here, morphological and functional). Three related questions are addressed: (1) Do herbivorous lizards show evidence of convergence in skull and lower jaw morphology? (2) What, if any, is the morphospace pattern associated with this convergence? (3) Is it possible to predict the direction of convergence using functional models? Relative warp analysis and permutation tests reveal that the skulls and lower jaws of herbivorous lizards do show evidence of convergence. Herbivore skulls deviate from their carnivorous or omnivorous sister groups toward the same area of morphospace. Without a phylogenetic perspective, this pattern would not be recognizable. Lower jaws of herbivores are not convergent in morphology but are convergent in function: herbivores deviate away from their carnivorous sister groups toward higher values of mechanical advantage. These results illustrate the desirability of quantitative methods, informed by phylogenetic information, in the study of convergence.     

Morphologie des Gebisses und Nahrungspraferenzen von dreizehn adriatischen Blenniiden (Teleostei, Perciformes)

The morphology and arrangement of the teeth in 13 sympatric species of the genus Blennius were investigated by SEM. All the species were collected in the upper littoral of the Northern Adriatic near Rovinj (Yugoslavia) and represent the total species inventory of the genus Blennius in this area. After analysing the content and length of the intestine, four groups with different feeding habits could be distinguished to which the morphological adaptations of the teeth could be correlated. There is a non-selective omnivorous group of Aufwuchs-grazer which take the inhabiting vagilfauna {Blennius gattorugine, B. incognitas, B. tentacularis ), a herbivorous group ( B. sanguinolentus, B. sphynx, B. canevae ), a carnivorous group ( B. trigloides, B. dalmatinus, B. rouxi ), and a linking group between omnivorous grazers and carnivores (B. adriaticus, B. pavo, B. nigriceps). B. galerita shows a preponderance of comblike teeth and feeds exclusively scraping microscopic algae from the rocky substrate. The morphology and position of the caniniforms vary greatly within the investigated species. The dentition on the vomer is lacking in five species and seems of no consequence in the uptake of food.     

A Case of Neospora Associated Bovine Abortion in Sweden

Neospora caninum is a recently recognized protozoan organism that causes fatal neuromuscular disease in dogs and abortions and stillbirths in cattle and other animals (Dubey & Lindsay 1993). The parasite is morphologically similar and phylogenetically very closely related to the cyst-forming coccidium Toxoplasma gondii (Ellis et al. 1994, Holmdahl et al. 1994). This group of parasites has a two-host life cycle principally involving a carnivorous definitive host and a herbivorous or omnivorous intermediate host. However, with N. caninum, there is as yet no knowledge of any definitive host harbouring sexual stages of the parasite. The only known route of transmission is vertical from mother to foetus (Dubey & Lindsay 1993).     

The ecology and macroecology of mammalian home range area

Although many studies employ allometric relationships to demonstrate possible dependence of various traits on body mass, the relationship between home range size and body mass has been perhaps the most difficult to understand. Early studies demonstrated that carnivorous species had larger home ranges than herbivorous species of similar mass. These studies also argued that scaling relations (e.g., slopes) of the former were steeper than those of the latter and explained this in terms of the distribution of food resources, which are more uniformly distributed for most herbivores than for carnivores. In contrast to these studies, we show that scaling relations of home ranges for carnivorous mammals do not differ significantly from those of herbivorous and omnivorous species and that all three exhibit slopes that are significantly steeper than predicted on the basis of energetic requirements. We also demonstrate that home range size is constrained to fit within a polygonal constraint space bounded by lines representing energetic and/or biophysical limitations, which suggests that the log-linear relationship between home range area and mass may not be the appropriate function to compare against the energetically predicted slopes of 0.75 or 1.0. It remains unclear, however, why the slope of the relationship between home range area and body mass, whether based on raw data or on constraint lines, always exceeds that predicted by the energetic needs hypothesis.     

Do fish regulate phytoplankton in shallow eutrophic Northeast Brazilian reservoirs?

SUMMARY 1. In a comparative study, we examined the potential for fish to structure planktonic food webs in shallow mesotrophic to hypereutrophic Northeast Brazilian reservoirs. The food webs were dominated by three guilds of fish (facultative piscivores, generalist planktivores and omnivores), small herbivorous zooplankton and bloom‐forming cyanobacteria, with few littoral macrophytes. 2. A principal component's analysis on data from 13 reservoirs (27 sampling dates in 1995–99) revealed that euphotic depth, the relative density of phytoplankton (i.e. the percentage of overall phytoplankton density) represented by cyanobacteria, and the relative biomass of fish (i.e. percentage of overall biomass) represented by omnivores and facultative piscivores, explained most of the variance in the data. Physico‐chemical conditions, lake morphometry and rainfall were secondary factors. 3. Phytoplankton was related to fish guild structure. Chlorophyll concentration increased with total phosphorus and the relative biomass of omnivorous fish, decreased with the relative biomass of facultative piscivores, but was unrelated to the biomass and mean body size of herbivorous zooplankton. Chlorophyll concentration and the densities of filamentous and colonial cyanobacteria decreased with the ratio of the biomass of facultative piscivores to that of omnivores (FP : OM). 4. We propose two complementary mechanisms for the observed relationships between fish and phytoplankton. At a low biomass of facultative piscivores, juvenile zooplanktivorous fishes may induce a trophic cascade on zooplankton in the littoral zone. Regardless of piscivore biomass, piscivores and omnivores may regulate phytoplankton via multichannel omnivory because of the predominance of omnivorous or detritivorous foraging behaviour. 5. Manipulative experiments are needed to explore further whether, depending on priorities in the use of the reservoir, fisheries management could alter the FP : OM ratio either to enhance fish yields or to reduce phytoplankton densities and cyanobacterial blooms.     

Morphological and histological study of eggs of six species of the Triatoma genus (Hemiptera: Reduviidae)

The objective of this study was to analyze the morphological and histological characteristics of eggs from six triatomine species in order to obtain a generic and specific characterization of this group of Trypanosoma cruzi vectors and better understand their phylogenetic and taxonomic aspects. The eggs of the respective species came from the collection of the Laboratório de Triatomíneos e Culicídeos da Faculdade de Saúde Pública/USP, from the Insetário do Servi?o Especial de Saúde de Araraquara - SESA and from the Triatomine insectary of the Laboratório Nacional e Internacional de Referência em Taxonomia de Triatomíneos (FIOCRUZ), in Rio de Janeiro. Morphological studies were done with optical microscopy and scanning electron microscopy. Histological analyses used only optical microscopy. All of the species analyzed showed a predominance of hexagonal cells. The exchorion of Triatoma breyeri Del Ponte, T. costalimai Verano Galv?o, and T. tibiamaculata (Pinto) consists of unornamented cells, overlapping or slightly separated, with a smooth, padded appearance. Meanwhile, in T. matogrossensis Leite Barbosa, T. sherlocki Papa, Juberg, Carcavallo, Cerqueira Barata, and T. williami Galv?o, Souza Lima, the exchorion cells are ornamented on their entire surface with perforations and fissures. Egg histology showed undulations, pores, and orifices. The study helps to expand the generic and specific knowledge of the Triatominae subfamily. The characteristics identified in the exchorion of the eggshells can help separate close species. These new parameters will back the elaboration of future dichotomous keys, help to determine each vector species role and expand knowledge of the various species.     

Asymmetrical food web responses in trophic-level richness, biomass, and function following lake acidification

We tested for disproportional changes in annual and seasonal species richness and biomass among five trophic levels (phytoplankton, herbivorous, omnivorous, and carnivorous zooplankton, and fish) as well as altered trophic structure and ecosystem function following the 5-year experimental acidification of Little Rock Lake (Wisconsin, USA) from pH 6.1 to 4.7. Abiotic and biotic controls of trophic level response during acidification were also identified. Asymmetric reductions of species richness among trophic levels, separated by life stage and feeding type, were evident and changes in trophic structure were most pronounced by the end of the acidification period. Relative declines in richness of fish and zooplankton were greater than phytoplankton, which were generally unaffected, leading to a reduction of upper trophic level diversity. Each of the lower four trophic levels responded to a distinct combination of abiotic and biotic variables during acidification. pH was identified as a direct driver of change for only carnivorous zooplankton, while all other trophic levels were affected more by indirect interactions caused by acidification. Fluctuations in ecosystem function (zooplankton biomass and primary production) were also evident, with losses at all trophic levels only detected during the last year of acidification. The acidified basin displayed a tendency for greater variation in biomass for upper trophic levels relative to reference conditions implying greater unpredictability in ecosystem function. Together, these results suggest that trophic asymmetry may be an important and recurring feature of ecosystem response to anthropogenic stress.