FACTORS INFLUENCING THE DISTRIBUTION OF DIGENETIC TREMATODE INFECTIONS IN A MUDSNAIL (HYDROBIA VENTROSA) POPULATION INHABITING SALT MARSH PONDS IN ICELAND

2004 ◽  
Vol 90 (1) ◽  
pp. 50-59 ◽  
Author(s):  
Karl Skirnisson ◽  
Kirill V. Galaktionov ◽  
Eugeny V. Kozminsky
Keyword(s):  
Salt Marsh ◽  
Digenetic Trematode ◽  
Factors Influencing ◽  
Trematode Infections

Vegetation patterns in James Bay coastal marshes. III. Salinity and elevation as factors influencing plant zonations

1989 ◽  
Vol 67 (10) ◽  
pp. 2967-2974 ◽  
Author(s):  
J. C. Earle ◽  
K. A. Kershaw
Keyword(s):  
Salt Marsh ◽  
Salinity Gradient ◽  
Detrended Correspondence Analysis ◽  
Distribution Patterns ◽  
Environmental Data ◽  
Plant Distribution ◽  
Coastal Marsh ◽  
James Bay ◽  
Factors Influencing ◽  
Community Types

Plant zonations and selected environmental variables were studied in a subarctic coastal marsh at Ekwan Point, James Bay, Ont. Eight distinct community types were identified using two-way indicator species analysis classification (TWINSPAN). These were interpreted as a primary successional sequence. The eight communities were found to conform closely to the classical marsh zonations based on elevation and tidal influence: (1) lower salt marsh, (2) middle salt marsh, (3) upper salt marsh, (4) saline meadow, (5) freshwater meadow, and (6) freshwater fen. Environmental data collected along the vegetation transects indicated that changes in elevation and soil-water salinity probably influence species distributions. A species ordination using detrended correspondence analysis (DECORANA) revealed several trends in plant distribution patterns. Consideration of the environmental affinities of species separated along three ordination axes suggested that salinity and elevation, water content, and soil texture were probably important factors influencing successional processes in the marsh during at least the last century. An inverse salinity gradient, which has been reported at many sites along the west coast of Hudson and James bays, was not found at Ekwan Point.

scholarly journals Factors Influencing Colonization and Survival of Juvenile Blue Crabs Callinectes sapidus in Southeastern U.S. Tidal Creeks

Diversity ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 491
Author(s):  
Paul J. Rudershausen ◽  
Jeffery H. Merrell ◽  
Jeffrey A. Buckel
Keyword(s):  
Salt Marsh ◽  
Land Cover ◽  
Blue Crab ◽  
Detection Probability ◽  
Tidal Creek ◽  
Callinectes Sapidus ◽  
Blue Crabs ◽  
Tidal Creeks ◽  
Occupancy Dynamics ◽  
Factors Influencing

Tidal creeks along the southeastern U.S. and Gulf of Mexico coastlines provide nursery habitats for commercially and ecologically important nekton, including juvenile blue crabs Callinectes sapidus, a valuable and heavily landed seafood species. Instream and watershed urbanization may influence the habitat value that tidal creeks provide to blue crabs. We investigated natural and anthropogenic factors influencing juvenile blue crab occupancy dynamics in eight first-order tidal creeks in coastal North Carolina (USA). An auto-logistic hierarchical multi-season (dynamic) occupancy model with separate ecological and observation sub-models was fitted to juvenile blue crab presence/absence data collected over replicate sampling visits in multiple seasons at three fixed trapping sites in each creek. Colonization and survival are the processes operating on occupancy that are estimated with this formulation of the model. Covariates considered in the ecological sub-model included watershed imperviousness, the percent of salt marsh in each creek’s high tide area, percent salt marsh edge, site-level water depth, and site-level salinity. Temperature, salinity, and dissolved oxygen were covariates considered in the observation sub-model. In the ecological sub-model, watershed imperviousness was a meaningful negative covariate and site-level salinity was a positive covariate of survival probability. Imperviousness and salinity were each marginally meaningful on colonization probability. Water temperature was a positive covariate of detection probability in the observation sub-model. Mean estimated detection probability across all sites and seasons of the study was 0.186. The results suggest that development in tidal creek watersheds will impact occupancy dynamics of juvenile blue crabs. This places an emphasis on minimizing losses of natural land cover classes in tidal creek watersheds to reduce the negative impacts to populations of this important species. Future research should explore the relationship between imperviousness and salinity fluctuations in tidal creeks to better understand how changing land cover influences water chemistry and ultimately the demographics of juvenile blue crabs.

scholarly journals Infection byParorchis acanthus(Trematoda) decreases grazing by the keystone gastropod,Littoraria irrorata

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4544 ◽  
Author(s):  
Joseph P. Morton
Keyword(s):  
Salt Marsh ◽  
Host Species ◽  
Parasite Prevalence ◽  
Digenetic Trematode ◽  
Ecosystem Stability ◽  
Grazing Behavior ◽  
Littoraria Irrorata ◽  
Ecological Influence ◽  
Parorchis Acanthus

Parasites are well-known to alter the behavior of their hosts, but there is still a paucity of knowledge about how parasites modify the behavior of many ecologically influential host species. I studied the keystone grazer, the salt marsh periwinkle(Littoraria irrorata),to determine the influence of infection by the digenetic trematode,Parorchis acanthus,on its grazing behavior. Comparative laboratory grazing studies of wild-collected and experimentally infected snails revealed thatParorchisdecreased grazing on liveSpartinaby more than 80%. Because of the large ecological influence ofLittorariain southern U.S. marshes, parasite modification of snail grazing may have ramifications for marsh ecosystem stability if parasite prevalence is sufficiently high.

scholarly journals Effects of agrochemicals on disease severity of Acanthostomum burminis infections (Digenea: Trematoda) in the Asian common toad, Duttaphrynus melanostictus

2017 ◽  
Author(s):  
Uthpala A. Jayawardena ◽  
Jason R. Rohr ◽  
Priyanie H. Amerasinghe ◽  
Ayanthi N. Navaratne ◽  
Rupika S. Rajakaruna
Keyword(s):  
Amphibian Declines ◽  
Digenetic Trematode ◽  
Parasitic Infections ◽  
Common Toad ◽  
Duttaphrynus Melanostictus ◽  
Pesticide Treatment ◽  
Complex Interactions ◽  
Skin Ulcers ◽  
Combined Exposures ◽  
Trematode Infections

AbstractBackgroundAgrochemicals are widely used in many parts of the world posing direct and indirect threats to organisms. Xenobiotic-related disease susceptibility is a common phenomenon and a proposed cause of amphibian declines and malformations. For example, parasitic infections combined with pesticides generally pose greater risk to both tadpoles and adult frogs than either factor alone. Here, we report on experimental effects of lone and combined exposures to cercariae of the digenetic trematode Acanthostomum burminis and ecologically relevant concentrations of (0.5 ppm) four pesticides (insecticides: chlorpyrifos, dimethoate; herbicides: glyphosate, propanil) on the tadpoles and metamorphs of the Asian common toad, Duttaphrynus melanostictus.ResultsAll 48 cercaraie successfully penetrated each host suggesting that the pesticides had no short-term detrimental effect on cercarial penetration abilities. When the two treatments were provided separately, both cercariae and pesticides significantly decreased the survival of tadpoles and metamorphs and increased developmental malformations, such as scoliosis, kyphosis, and skin ulcers. Exposure to cercariae and the two insecticides additively reduced host survival. In contrast, mortality associated with the combination of cercariae and herbicides was less than additive. The effect of cercariae on malformation incidence depended on the pesticide treatment; dimethoate, glyphosate, and propanil reduced the number of cercarial-induced malformations relative to both the control and chlorpyrifos treatments.ConclusionsThese results show that ecologically relevant concentrations of the tested agrochemicals had minimal effects on trematode infections, in contrast to others studies which showed that these same treatments increased the adverse effects of these infections on tadpoles and metamorphs of the Asian common toad. These findings reinforce the importance of elucidating the complex interactions among xenobiotics and pathogens on sentinel organisms that may be indicators of risk to other biota.

scholarly journals Factors influencing occupancy and density of salt marsh songbirds in northeast Florida

2020 ◽  
Vol 91 (2) ◽  
pp. 156-169
Author(s):  
Amy C. Schwarzer ◽  
W. Andrew Cox ◽  
Brett Tornwall
Keyword(s):  
Salt Marsh ◽  
Factors Influencing

Factors influencing adhesive bonding at the bone/implant interface

1992 ◽  
Vol 50 (2) ◽  
pp. 1114-1115
Author(s):  
Julie A. Martini ◽  
Robert H. Doremus
Keyword(s):  
Electron Microscopy ◽  
Adhesive Bonding ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Bone Implant ◽  
Factors Influencing ◽  
Lr White ◽  
Transmission Electron ◽  
New Zealand White Rabbits ◽  
Scanning Electron

Tracy and Doremus have demonstrated chemical bonding between bone and hydroxylapatite with transmission electron microscopy. Now researchers ponder how to improve upon this bond in turn improving the life expectancy and biocompatibility of implantable orthopedic devices.This report focuses on a study of the- chemical influences on the interfacial integrity and strength. Pure hydroxylapatite (HAP), magnesium doped HAP, strontium doped HAP, bioglass and medical grade titanium cylinders were implanted into the tibial cortices of New Zealand white rabbits. After 12 weeks, the implants were retrieved for a scanning electron microscopy study coupled with energy dispersive spectroscopy.Following sacrifice and careful retrieval, the samples were dehydrated through a graduated series starting with 50% ethanol and continuing through 60, 70, 80, 90, 95, and 100% ethanol over a period of two days. The samples were embedded in LR White. Again a graduated series was used with solutions of 50, 75 and 100% LR White diluted in ethanol.

Factors Influencing Electrophysiologic Responsivity in Normal Adults

1965 ◽  
Vol 8 (4) ◽  
pp. 323-347
Author(s):  
Robert Goldstein ◽  
Benjamin RosenblÜt
Keyword(s):  
Conditioned Stimulus ◽  
White Light ◽  
Pure Tone ◽  
Alpha Rhythm ◽  
White Women ◽  
White Men ◽  
Inverse Relation ◽  
Factors Influencing ◽  
Electrodermal Responses ◽  
Normal Adults

Electrodermal and electroencephalic responsivity to sound and to light was studied in 96 normal-hearing adults in three separate sessions. The subjects were subdivided into equal groups of white men, white women, colored men, and colored women. A 1 000 cps pure tone was the conditioned stimulus in two sessions and white light was used in a third session. Heat was the unconditioned stimulus in all sessions. Previously, an inverse relation had been found in white men between the prominence of alpha rhythm in the EEG and the ease with which electrodermal responses could be elicited. This relation did not hold true for white women. The main purpose of the present study was to answer the following questions: (1) are the previous findings on white subjects applicable to colored subjects? (2) are subjects who are most (or least) responsive electrophysiologically on one day equally responsive (or unresponsive) on another day? and (3) are subjects who are most (or least) responsive to sound equally responsive (or unresponsive) to light? In general, each question was answered affirmatively. Other factors influencing responsivity were also studied.

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