Planktonic invaders of the St. Lawrence estuarine transition zone: environmental factors controlling the distribution of zebra mussel veligers

2003 ◽  
Vol 60 (10) ◽  
pp. 1245-1257 ◽  
Author(s):  
Christine Barnard ◽  
Jean-Jacques Frenette ◽  
Warwick F Vincent
Keyword(s):  
Environmental Factors ◽  
Transition Zone ◽  
Total Phosphorus ◽  
Dreissena Polymorpha ◽  
Prey Availability ◽  
Larval Fish ◽  
Positive Association ◽  
Horizontal Distribution ◽  
Fish Nursery ◽  
Negative Impacts

The St. Lawrence estuarine transition zone (ETZ) is a productive ecosystem supporting a larval fish nursery. Since 1994, Dreissena polymorpha veligers have become the dominant zooplankton (up to 260 individuals·L–1). The environmental factors controlling their distribution across the ETZ and their potential impact on the plankton were determined. Their horizontal distribution was limited by salinity, with maximum decreases in concentration at 2‰. A sharp decline in prey availability at >2‰ may be a secondary stressor for the veligers, in addition to the direct effects of salinity. Their vertical distribution was homogeneous throughout the water column, even in the presence of a pycnocline. Redundancy analysis showed that veliger concentrations were positively correlated with temperature and turbidity and negatively correlated with salinity and total phosphorus. Veligers were also positively correlated with chlorophyll a and picophytoplankton concentrations, suggesting little effect on their phytoplankton prey. Moreover, the veligers were positively correlated with the sestonic ratio of particulate to total phosphorus, indicating their positive association with good food quality. The veligers appear to have no severe negative impacts on the ETZ plankton community and are restricted to favourable conditions for their survival in the upstream, low salinity region of the ETZ.

Size-selective predation by river otter (Lontra canadensis) improves refuge properties of shallow coastal marine nursery habitats

2008 ◽  
Vol 86 (11) ◽  
pp. 1324-1328 ◽  
Author(s):  
D. Cote ◽  
R. S. Gregory ◽  
H. M.J. Stewart
Keyword(s):  
Shallow Water ◽  
Atlantic Cod ◽  
Prey Availability ◽  
Juvenile Fish ◽  
Lontra Canadensis ◽  
River Otter ◽  
Fish Nursery ◽  
Piscivorous Fish ◽  
Risk Of Predation ◽  
Nursery Habitats

Young fish often avoid deep water to reduce predation risk from larger fish. Less clear are explanations for the avoidance of shallows by large piscivorous fish; however, one hypothesis suggests that this distribution reduces contact with depth-limited semi-aquatic mammal and bird piscivores. We determined prey size selection of the river otter ( Lontra canadensis (Schreber, 1777)) to test the hypothesis that larger fish are at elevated risk in shallow coastal waters in Newman Sound, Newfoundland, during June–November 2001 and May 2002. We compared otter diet (scat analysis) and prey availability (seine sampling) to test this hypothesis. Five fish taxa (Atlantic cod ( Gadus morhua L., 1758), Greenland cod ( Gadus ogac Richardson, 1836), shorthorn sculpin ( Myoxocephalus scorpius (L., 1758)), cunner ( Tautogolabrus adspersus (Walbaum, 1792)), and winter flounder ( Pseudopleuronectes americanus (Walbaum, 1792))) dominated the shallow-water fish community and were sufficiently abundant in otter scats to examine feeding preferences. Larger, piscivorous fish were selected by otters, suggesting that they were at greater risk of predation than smaller fish, consistent with our hypothesis that depth-limited, diurnally active predators restrict large fish from hunting in shallow water during daytime. We suggest that depth-limited air-breathing predators may reduce the presence of such predatory fish in shallow-water juvenile fish nursery habitats.

scholarly journals Altered Adipose Tissue DNA Methylation Status in Metabolic Syndrome: Relationships Between Global DNA Methylation and Specific Methylation at Adipogenic, Lipid Metabolism and Inflammatory Candidate Genes and Metabolic Variables

2019 ◽  
Vol 8 (1) ◽  
pp. 87 ◽  
Author(s):  
Daniel Castellano-Castillo ◽  
Isabel Moreno-Indias ◽  
Lidia Sanchez-Alcoholado ◽  
Bruno Ramos-Molina ◽  
Juan Alcaide-Torres ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Dna Methylation ◽  
Adipose Tissue ◽  
Lipid Metabolism ◽  
Environmental Factors ◽  
Metabolic Diseases ◽  
Methylation Status ◽  
Serum Triglyceride ◽  
Positive Association ◽  
Global Dna Methylation

Metabolic syndrome (MetS) has been postulated to increase the risk for type 2 diabetes, cardiovascular disease and cancer. Adipose tissue (AT) plays an important role in metabolic homeostasis, and AT dysfunction has an active role in metabolic diseases. MetS is closely related to lifestyle and environmental factors. Epigenetics has emerged as an interesting landscape to evaluate the possible interconnection between AT and metabolic disease, since it can be modulated by environmental factors and metabolic status. The aim of this study was to determine whether MetS has an impact on the global DNA methylation pattern and the DNA methylation of several genes related to adipogenesis (PPARG, PPARA), lipid metabolism (RXRA, SREBF2, SREBF1, SCD, LPL, LXRb), and inflammation (LRP1 C3, LEP and TNF) in visceral adipose tissue. LPL and TNF DNA methylation values were significantly different in the control-case comparisons, with higher and lower methylation respectively in the MetS group. Negative correlations were found between global DNA methylation (measured by LINE-1 methylation levels) and the metabolic deterioration and glucose levels. There were associations among variables of MetS, BMI, and HOMA-IR with DNA methylation at several CpG positions for the studied genes. In particular, there was a strong positive association between serum triglyceride levels (TG) with PPARA and LPL methylation levels. TNF methylation was negatively associated with the metabolic worsening and could be an important factor in preventing MetS occurrence according to logistic regression analysis. Therefore, global DNA methylation and methylation at specific genes related to adipogenesis, lipid metabolism and inflammation are related to the etiology of MetS and might explain in part some of the features associated to metabolic disorders.

scholarly journals Aquatic flora in two Indian ponds near Kolkata, West Bengal: Implications for conservation

1970 ◽  
Vol 14 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Gautam Mukhopadhyay ◽  
Sourav Sengupta ◽  
Anjana Dewanji
Keyword(s):  
Chemical Constituents ◽  
Positive Association ◽  
Alternanthera Philoxeroides ◽  
Cladophora Glomerata ◽  
High Coverage ◽  
Hydrodictyon Reticulatum ◽  
Aquatic Flora ◽  
Plant Taxon ◽  
Negative Impacts ◽  
Insight Into

Occurrence, coverage and chemical constituents of aquatic flora were studied in two Indian ponds over a period of 39-month in order to gain an insight into their associations and infestation for implications in conservation and management. Species diversity was recorded in presence of two invasive species (Alternanthera philoxeroides (Martius) Griseb. and Lemna aequinoctialis Welwitsch). These species should be managed in view of their beneficial uses. Nymphaea pubescens Willd, a threatened species, was recorded. Positive association of Nymphoides hydrophylla (Loureiro) O. Kuntze with Alternanthera philoxeroides and Vallisneria spiralis L. showed that spatially separated habitats are useful for conservation. Azolla pinnata R. Brown, an useful species and Rotala rotundifolia (F. Hamilton ex Roxburgh) Koehne, an uncommon species, were able to produce high coverage in their brief occurrence - important for their conservation. Similar feature as observed in Cladophora glomerata (L.) Kütz and Hydrodictyon reticulatum (L.) Lagerh. is useful for management of these species due to their negative impacts. Key words: Aquatic flora, Species composition, Occurrence, Coverage, Nitrogen, Phosphorus, Management DOI: 10.3329/bjpt.v14i1.519 Bangladesh J. Plant Taxon. 14(1): 13-24, 2007 (June)

Oat β-glucans: An evaluation of eastern Canadian cultivars and unregistered lines

1993 ◽  
Vol 73 (2) ◽  
pp. 429-436 ◽  
Author(s):  
S. S. Miller ◽  
R. G. Fulcher ◽  
D. J. Vincent ◽  
J. Weisz
Keyword(s):  
Content Analysis ◽  
Environmental Factors ◽  
Avena Sativa ◽  
Rank Order ◽  
Positive Association ◽  
Kernel Weight ◽  
Negative Association ◽  
Significant Positive Association ◽  
Factors Influencing ◽  
Oat Cultivars

The (1-3), (1-4)-β-D-glucan (β-glucan) content of a number of domestic Canadian oat cultivars and selected unregistered lines was determined to establish the range of β-glucan content in eastern Canadian oat varieties. Seed samples were taken from oats grown at five locations over 3 years in an attempt to assess the effect of environment on variation in β-glucan content. Analysis of variance indicated that the greater source of variation in β-glucan content was due to genetic rather than environmental factors. The highest β-glucan cultivar (Marion) was about 30% higher than the lowest cultivars (OA516-2 and Donald). Differences in β-glucan content among the intermediate cultivars were generally smaller, and in some cases not significant, although the rank order of the cultivars among environments was consistent. A low, but significant, negative association between β-glucan content and precipitation, and a low, but significant, positive association between β-glucan content and temperature was found, but these were not dominant factors influencing β-glucan levels in oats. There was no consistent association between β-glucan content and protein, oil, thousand kernel weight or grain yield (kg/hectare). Key words: Oat, Avena sativa, β-glucan, variation

The effect of dreissenid invasions on chlorophyll and the chlorophyll : total phosphorus ratio in north-temperate lakes

2011 ◽  
Vol 68 (2) ◽  
pp. 319-329 ◽  
Author(s):  
S. N. Higgins ◽  
M. J. Vander Zanden ◽  
L. N. Joppa ◽  
Y. Vadeboncoeur
Keyword(s):  
Total Phosphorus ◽  
Dreissena Polymorpha ◽  
Trophic Status ◽  
Hierarchical Modeling ◽  
Significant Decline ◽  
Analysis Of Covariance ◽  
Temperate Lakes ◽  
Regression Approach ◽  
North Temperate Lakes ◽  
Lake Size

We investigated the effects of dreissenid mussel ( Dreissena polymorpha and D. rostriformis bugensis ) invasions on the concentrations of chlorophyll a (Chl) and total phosphorus(TP), and the Chl:TP ratio within 27 north-temperate lakes that spanned large gradients in lake size and trophic status, using two approaches: (i) regression analysis and (ii) hierarchical modeling. Overall, Chl declined by 40%–45% after dreissenid invasion and the magnitude of effect was structured by epilimnetic volume within stratified, but not nonstratified (mixed) lakes. Declines in TP over the invasion period were significant only for stratified systems and were smaller (∼16% reduction from pre-invasion values) than for Chl. Across the complete trophic gradient (i.e., among lakes) the regression approach (analysis of covariance) indicated a significant decline in the intercept of the Chl:TP, but not the slope. In contrast, hierarchical modeling indicated a decline in the slope of Chl:TP among lakes between pre- and post-invasion periods. As with Chl, the effect of dreissenids on Chl:TP declined with increases in epilimnetic volume in stratified, but not nonstratified lakes. Dreissenid effects on Chl were prolonged, with no indication of diminishing within 7–10 years of invasion.

The role of wind-forcing in the distribution of larval fish in Galway Bay, Ireland

2012 ◽  
Vol 93 (2) ◽  
pp. 471-478 ◽  
Author(s):  
Stephen Comerford ◽  
Deirdre Brophy
Keyword(s):  
Environmental Factors ◽  
Generalized Linear Model ◽  
Larval Fish ◽  
Juvenile Fish ◽  
Residual Circulation ◽  
Tidal State ◽  
Merlangius Merlangus ◽  
Sampling Season ◽  
Distribution Of Fish

The ichthyoplankton of Galway Bay was sampled over the spring and summer of 2007 and 2008 to determine what environmental factors influenced the distribution of larval and early juvenile fish. A total of 549 fish representing 27 taxa were caught. Catches decreased throughout each sampling season, and were generally poor in 2007. Catches were numerically dominated by sprat (Sprattus sprattus), dab (Limanda limanda), sand eel (Hyperoplus immaculatus) and whiting (Merlangius merlangus). Environmental factors driving distribution of fish were modelled using a binomial generalized linear model. The strength and direction of wind in the five days preceding sampling was the only significant environmental factor. Sustained onshore winds increased the probability of encountering larval fish in the areas sampled. The rainfall, tidal state, tow depth and wind conditions during sampling were not significant. Among the parameters measured it appears that onshore winds sufficiently strong to overcome the residual circulation are the main physical driver for the distribution of larval fish in Galway Bay.

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