The physiological response of fishes to a deficiency of cyanocobalamin and folic acid

Environmental adaptive response of fishes to the nutritional deficiencies of two important vitamins of the B-group viz . cyanocobalamin and folacin has been investigated using growth, haematology and haemopoiesis as physiological indices. Extended studies lasting 105 days revealed a consistent decrease in growth or even loss of weight when cyanocobalamin and folacin were absent from the diet. The combined deficiency of these two vitamins had an additive rather than synergistic effect on growth. The feed conversion values of all the deficient groups were significantly low as compared to the control. Haematologically the occurrence of anaemia and leucocytosis were recorded in all the deficient groups, the former mainly of megaloblastic type. Differential WBC counts revealed that leucocytosis was mainly due to an increase in thrombocyte population and cosinophils. On the other hand, there was an relative decrease of other nongranulocytes and granulocytes. Erythro-poietic investigations revealed a decreased proliferation rate of the reticuloendothelial cells and an increased number of young and mature reticulocytes and immature erythrocytes into the peripheral blood.     

Seasonal patterns of stream macroinvertebrate communities in response to anthropogenic stressors in monsoonal Taiwan

Freshwater ecosystems are affected by a variety of anthropogenic stressors. Temporal variability of biotic communities in these ecosystems makes it difficult to accurately assess the impacts of specific stressors, which has seldom been considered in understudied regions of Asia. We studied the seasonal effects of anthropogenic stressors on stream macroinvertebrates based on sampling every three months over two years at five stream sites in central Taiwan. Several macroinvertebrate metrics (taxon richness, Shannon diversity index, and relative abundance of Trichoptera) were lower during the wet season than the dry season. The presence of dams caused changes in the structure of macroinvertebrate communities, decreased the seasonal variability in relative abundances of Trichoptera, as well as resulted in lower dissolved inorganic nitrogen concentrations and larger substrate size. The presence of urban areas had less or no influence on environmental factors and structural changes. However, significantly lower total abundance, taxon richness, and relative abundance of Trichoptera occurred in the presence of either dams and/or urban areas. One key management implication from the present study is that bioassessment utilizing macroinvertebrates should be facilitated by awareness of the potential role of temporal factors on the effects of anthropogenic stressors, especially in monsoonal Asia.     

Temporal shifts as elusive responses to anthropogenic stressors in a mammal community

Conservation decision-making often relies on species’ distribution changes in response to anthropogenic disturbances but overlook their temporal responses. Filling the knowledge gap on the temporal shifts as elusive responses of wild animals to human activity is important because this may provide information for more proactive conservation planning. In this study, we used camera traps in a field survey technique to investigate the trade-offs between spatial and temporal responses of a mammal community to major human activities in Qinling Mountains, China. We focused on five most abundant mammalian species including giant panda (Ailuropoda melanoleuca), takin (Budorcas taxicolor), wild boar (Sus scrofa), tufted deer (Elaphodus cephalophus), and Chinese goral (Naemorhedus griseus), and examined the drivers of, and the trade-offs between the change of their spatial distributions and daily activity patterns in response to anthropogenic disturbances. We found that in response to human interferences, giant panda and takin mainly changed their distributions, while wild boar, tufted deer and Chinese goral altered their daily activity patterns, indicating the elusive responses of the latter species under anthropogenic stressors. In addition, anthropogenic stressors such as farming and tourism have more profound impacts on mammal communities than previously revealed by species distribution modeling only. For nature reserves that aim to conserve multiple species simultaneously, a more flexible, adaptive management framework is thus needed to capture the trade-offs between multiple species’ spatial and temporal responses to anthropogenic disturbance.

     

Ecological impact of alien marine fishes: insights from freshwater systems based on a comparative review

Hydrobiologia - We review the literature of marine non-indigenous fishes (NIF) in order to summarize information on their ecological impacts and to compare successful invading freshwater fishes...     

The evolution of religious belief in humans: a brief review with a focus on cognition

Religion has been a widely present feature of human beings. This review explores developments in the evolutionary cognitive psychology of religion and provides critical evaluation of the different theoretical positions. Generally scholars have either believed religion is adaptive, a by-product of adaptive psychological features or maladaptive and varying amounts of empirical evidence supports each position. The adaptive position has generated the costly signalling theory of religious ritual and the group selection theory. The by-product position has identified psychological machinery that has been co-opted by religion. The maladaptive position has generated the meme theory of religion. The review concludes that the by-product camp enjoys the most support in the scientific community and suggests ways forward for an evolutionarily significant study of religion.     

Behavioral thermoregulatory abilities of tropical coral reef fishes: a comparison with temperate freshwater and marine fishes

Synopsis Eight species in six different families of tropical marine reef fishes from the Indo-West Pacific region (Naso lituratus, Zebrasoma.flavescens, Balistes fuscus, B. vidua, Forcipiger longirostris, Echidna zebra, Cromileptes altivelis, Canthigaster jactator) were tested for ability to thermoregulate behaviorally in electronic shuttleboxes. All of these species preferred mean temperatures between 20 and 30°C, but differed considerably in thermoregulatory precision. All species avoided lethal high or low temperatures (i.e., they did not die during the tests), and some species thermoregulated as precisely as temperate species. Some temperate species prefer higher temperatures (above 30°C) than do these tropical reef species.     

The importance of turbellarians in the marine meiobenthos: a review

Recent data and opinions on meiofaunal ecology are briefly reviewed; and from scattered data, the place of turbellarians in the meiobenthic community is discussed. Turbellarian diversity, density, and biomass are higher in sandy habitats than in muddy bottoms. In sand, turbellarian diversity is of the same magnitude as that of other important meiofaunal taxa, while densities range between 7–25% of the total meiofauna. Mean individual turbellarian dry weight seems to be four times that of nematodes and in sandy habitats turbellarian biomass may be equal to or excede that of nematodes. Most turbellarian species may be considered as predators and in this respect may take the place occupied by macrofaunal species in muddy sediments. mens.

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The physiological control of feeding in corals: a review

Little is known about the factors that control food capture by the coral polyp and the way that internal physiological events may coordinate, or even modify, this behaviour. A total understanding of the nutritional dynamics of corals demands detailed study of their feeding behaviour, and recent advances in behavioural and electrophysiological techniques are starting to provide some insights into how polyps control this behaviour. This review describes our present understanding of the physiological control of feeding behaviour in corals and suggests new studies on food recognition, food capture, and ingestion.     

Back to the sea: secondary marine organisms from a biogeographical perspective

Secondary marine organisms belong to groups of terrestrial ancestry which have recolonized marine habitats. Some of them are, to various degrees, still dependent on the terrestrial habitat where they originated, which imposes certain limits in the expansion of their distribution range. This makes them an ideal subject for historical reconstruction. Here I perform biogeographical analyses on the global distribution of 12 groups of land-dependent secondary marine plants and animals (mangrove trees, sea turtles, sea snakes, seabirds and seals). When all groups are taken together, species diversity shows a unique bimodal pattern for each hemisphere, with high values in cold-temperate and tropical regions, but low values in mid-latitude regions. None of the individual groups considered reaches its highest species concentration in mid-latitude regions. This is shown to be due to the existence of three different species assemblages, inhabiting the three species-rich latitudinal bands (northern cold-temperate, tropical, and southern cold-temperate), and intermixing to a limited degree in the species-poor mid-latitude bands. This is evidence that secondary marine organisms diversified independently in cold-temperate and tropical regions, and strongly suggests that colonization from terrestrial habitats took place independently in the three species-rich latitudinal bands. Different constraints in the terrestrial habitat of origin are put forward as evolutionary incentives for colonizing the sea: glaciation processes in cold regions and competition in tropical regions.     

Survival, physiological response and recovery of enteric bacteria exposed to a polar marine environment.

Survival, sublethal injury, and recoverability of Escherichia coli, Enterococcus faecalis, Salmonella typhimurium, and Yersinia enterocolitica were investigated by using diffusion chambers over 54 to 56 days of in situ exposure to a polar marine environment (-1.8 degrees C; salinity, 34.5 ppt) at McMurdo Station, Antarctica. Plate counts were used to assess recoverability and injury, whereas direct viable counts (DVCs) and 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) reduction were utilized to determine substrate responsiveness and respiratory activity, respectively. T90 values (times for 10-fold decreases in numbers of recoverable cells) on nonselective medium were ca. 216 to 259 h for E. coli, S. typhimurium, and Y. enterocolitica and 432 h for E. faecalis. Sublethal injury was greater in populations of indicator bacteria than in pathogens. DVCs, CTC reduction, and plate counts indicated progressive increases in viable but nonculturable cells in E. coli, S. typhimurium, and Y. enterocolitica cultures throughout the 54-day exposure. Forty-eight-day exposure of E. coli, S. typhimurium, and Y. enterocolitica resulted in decreased optimal incubation temperatures for colony formation and inability to form colonies at 37 degrees C. The detection of responsive E. coli, S. typhimurium, and Y. enterocolitica by the DVC and CTC methods remained within 1% of inoculum values during 54 days of exposure, indicating some long-term persistence in the viable-but-nonculturable state. Percentages of respiring E. coli and S. typhimurium increased significantly upon addition of nutrients at all temperatures tested, indicating that nutrient availability rather than temperature limited enteric bacterial activity in this very cold environment. Large nutrient inputs to low-temperature marine environments may thus allow for the long-term persistence of enteric bacteria in a nonrecoverable state.     

The unfolded protein response in melanocytes: activation in response to chemical stressors of the endoplasmic reticulum and tyrosinase misfolding

Accumulation of proteins in the endoplasmic reticulum (ER) triggers the unfolded protein response (UPR), comprising three signaling pathways initiated by Ire1, Perk and Atf6 respectively. Unfolded protein response activation was compared in chemically stressed murine wildtype melanocytes and mutant melanocytes that retain tyrosinase in the ER. Thapsigargin, an ER stressor, activated all pathways in wildtype melanocytes, triggering Caspase 12-mediated apoptosis at toxic doses. Albino melanocytes expressing mutant tyrosinase showed evidence of ER stress with increased Ire1 expression, but the downstream effector, Xbp1, was not activated even following thapsigargin treatment. Attenuation of Ire1 signaling was recapitulated in wildtype melanocytes treated with thapsigargin for 8 days, with diminished Xbp1 activation observed after 4 days. Atf6 was also activated in albino melanocytes, with no response to thapsigargin, while the Perk pathway was not activated and thapsigargin treatment elicited robust expression of the downstream effector CCAAT-enhancer-binding protein homologous protein. Thus, melanocytes adapt to ER stress by attenuating two UPR pathways.     

The evolution of habitat specialisation in a group of marine triplefin fishes

There has been considerable interest in the directionality of resource specialisation during the diversification of lineages. We developed a quantitative method to investigate habitat specialisation in a radiation of New Zealand triplefin fishes, as habitat use appears to be an important axis of diversification in this marine group. The degree of specialisation in 15 species was calculated by comparing each individual to all other individuals of a species, thus allowing for quantitative distinction between species. Species differed in habitat specialisation, but Bayesian comparative methods found no directional trend in the evolution of resource use. Further analyses showed that specialisation had evolved gradually and was phylogenetically constrained, with most differences between species arising toward the tips of the tree. No correlation between the degree of specialisation and body size was detected in this group, suggesting that habitat specialisation evolved independently of body size. Habitat specialisation does not appear to have been an impediment to ecological diversification in this group. Rather, diversification in these fishes appears to have followed different evolutionary trajectories in habitat specialisation, one in which species have sub-partitioned available resources, and another in which species have expanded their use of resources. These findings support recent studies suggesting that diversification does not necessarily proceed from generalised ancestors to specialised descendants.     

The immune response in fish: a review

The literature relating to the immune response of fish has been reviewed. Non-specific immune mechanisms similar to those of other vertebrate classes occur in fish. Similarly specific cell-mediated immunity has been demonstrated at all levels of evolution, from the cyclostomes to the teleosts. A humoral antibody system also occurs in all classes offish but varies considerably in relation to phylogenetic status. In the cyclostomes, only immuno-proteins with properties intermediate between the immunoglobulms of vertebrates and the non-specific agglutinins and lysins of invertebrates have been demonstrated. In the elasmo-branchs and chondrosteans 7 and 19s irnmunoglobulins of IgM type occur. In holosteans the 19s form is predominant whereas in teleosts, 7 and 19s forms occur, with some evidence of specialization in the 7s form. In the phylogenetically most advanced fish, the Dipnoi, two immunoglobulin classes, structurally analogous to IgM and IgG, have been described.
A characteristic feature of both cell-mediated and antibody mediated immune responses in fish is their dependence upon environmental temperature. There is also evidence that, in some species at least, nutritional factors and behaviour patterns may also influence the immune response.
Attempts at artificial immunization of fish against infectious disease have met with varied success. It is probable that better results could be achieved with live vaccine strains, particularly if applied under conditions optimal for the immune responses.     

Natural and anthropogenic dispersal mechanisms in the marine environment: a study using cheilostome Bryozoa

The global geographic ranges occupied by 197 species of cheilostomate Bryozoa found in British waters were obtained by a literature survey. Morphological grade, larval mode, environmental tolerance, species abundance and the ability to raft and to foul shipping were all investigated as traits potentially able to affect the geographic ranges of these bryozoan species. When considered independently all variables except larval mode had a significant correlation with the geographic range occupied by a species. However, when controlling for the potentially confounding effects of the other covariates, only the ability to foul or raft and species abundance had a significant effect on median geographic range and only fouling and abundance had a significant effect over global ranges. The strength of the association between fouling ability and range suggests that transport upon the hulls of ships is a very important dispersal mechanism for bryozoans, as it is thought to be also for various other marine taxa. Potential long-term (evolutionary) consequences of increased ranges brought about by anthropogenic mechanisms are discussed.     

Postembryonal growth and its variability of the three marine fishes with special reference to the mechanism of growth variation in fishes

1. To study the relation of growth variation to the behaviour pattern, newly hatched Hemiramphus sajori, Chrysophrys major and Zebrias zebra were reared in 30 litter aquaria during one month, and body length was measured four times.
2. In Hemiramphus sajori coefficient of variation of body length (CV) first increased but showed a tendency to decrease with development of schooling behaviour.
3. In Chrysophrys major CV markedly increased and mode of the distribution curve of body length inclined towards the left side, associated with appearance of aggression and cannibalism.
4. In Zebrias zebra, when behaviour pattern changed from planktonic to demersal some of the small individuals nearly ceased growing. At that time CV of body length remarkably increased and the mode of the distribution curve of body length shifted towards the right side.
5. In all the species a positive correlation was seem between specific growth rate and initial body length soon after intensive feeding began. An negative correlation was observed in most of individuals of Hemiramphus sajori after the appearance of schooling behaviour. When a conspicuous increase in CV and skewness in distribution curve took place, a separate type of correlation was seen in large and small group in the population.
6. Based on above mentioned and other materials a general mechanism of growth variation in fishes was discussed.

     

Fluctuating asymmetry and exogenous stress in fishes: a review

Fluctuating asymmetry (FA), which has been examined in a variety of plants and animals, is widely promoted as a useful bioindicator of exogenous stressors in habitats, whether of natural or anthropogenic origin. Wildlife managers and researchers often use a specific group of organisms as an indicator of the health of a given habitat. The purpose of this review is to demonstrate that FA can be an effective fish biomonitoring tool by presenting a vote counting meta-analysis of 81 fish FA studies published between 1966 and the first half of 2009. The vote counts were analyzed with the G test for independence to determine whether the probability of observing significant morphological asymmetry is determined by character type, exogenous stressor type, or fish order. The information obtained from these papers and their analysis is then used to outline areas in which FA studies can be improved: (1) carefully considering character choice; (2) distinguishing between asymmetry types; (3) determining the level of measurement error in between-sides character variation; (4) determining baseline FA levels in populations; (5) increasing the number of laboratory studies which corroborate field observations of FA; (6) conducting true replications of studies to validate previous findings. Only with more critical experimental design and data analysis can FA be used as a powerful tool for assessing environmental degradation.