Short-term environmental variability and phytoplankton abundance in a shallow tidal estuary

1987 ◽  
Vol 96 (1) ◽  
pp. 115-121 ◽  
Author(s):  
W. Litaker ◽  
C. S. Duke ◽  
B. E. Kenney ◽  
J. Ramus
Keyword(s):  
Environmental Variability ◽  
Phytoplankton Abundance ◽  
Short Term ◽  
Tidal Estuary

scholarly journals Experimental evidence for foraminiferal calcification under anoxia

2014 ◽  
Vol 11 (14) ◽  
pp. 4029-4038 ◽  
Author(s):  
M. P. Nardelli ◽  
C. Barras ◽  
E. Metzger ◽  
A. Mouret ◽  
H. L. Filipsson ◽  
...  
Keyword(s):  
Environmental Variability ◽  
Sediment Cores ◽  
Adult Mortality ◽  
Short Term ◽  
Essential Information ◽  
Ample Evidence ◽  
Anoxic Conditions ◽  
Inhibition Of Growth ◽  
Foraminiferal Species ◽  
First Time

Abstract. Benthic foraminiferal tests are widely used for paleoceanographic reconstructions from a range of different environments with varying dissolved oxygen concentrations in the bottom water. There is ample evidence that foraminifera can live in anoxic sediments. For some species, this is explained by a switch to facultative anaerobic metabolism (i.e. denitrification). Here we show for the first time that adult specimens of three benthic foraminiferal species are not only able to survive, but are also able to calcify under anoxic conditions, at various depths in the sediment, and with or without nitrates. In fact, several specimens of Ammonia tepida (1–4%), Bulimina marginata (8–24%) and Cassidulina laevigata (16–23%) were able to calcify at different redox fronts of sediment cores, under laboratory conditions. This demonstrates ongoing metabolic processes, even in micro-environments where denitrification is not possible. Earlier observations suggest that the disappearance of foraminiferal communities after prolonged anoxia is not due to instantaneous or strongly increased adult mortality. Here we show that it cannot be explained by an inhibition of growth through chamber addition either. Our observations of ongoing calcification under anoxic conditions mean that geochemical proxy data obtained from benthic foraminifera in settings experiencing intermittent anoxia have to be reconsidered. The analysis of whole single specimens or of their successive chambers may provide essential information about short-term environmental variability and/or the causes of anoxia.

scholarly journals Short‐term estimates of phytoplankton growth and mortality in a tidal estuary

2018 ◽  
Vol 63 (6) ◽  
pp. 2411-2422 ◽  
Author(s):  
Sean R. Anderson ◽  
Quintin P. Diou‐Cass ◽  
Elizabeth L. Harvey
Keyword(s):  
Phytoplankton Growth ◽  
Short Term ◽  
Tidal Estuary

scholarly journals The endemic and endangered Maugean Skate (Zearaja maugeana) exhibits short-term severe hypoxia tolerance

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Andrea J Morash ◽  
Jeremy M Lyle ◽  
Suzanne Currie ◽  
Justin D Bell ◽  
Kilian M Stehfest ◽  
...  
Keyword(s):  
Environmental Variability ◽  
Cellular Stress Response ◽  
Hypoxia Tolerance ◽  
Conservation Strategies ◽  
Low Oxygen ◽  
Short Term ◽  
Environmental Challenges ◽  
Preferred Habitat ◽  
Short Term Exposure ◽  
Dissolved O2

Abstract The endangered and range-restricted Maugean skate (Zearaja maugeana) is subjected to large environmental variability coupled with anthropogenic stressors in its endemic habitat, Macquarie Harbour, Tasmania. However, little is known about the basic biology/physiology of this skate, or how it may respond to future environmental challenges predicted from climate change and/or increases in human activities such as aquaculture. These skate live at a preferred depth of 5–15 m where the dissolved oxygen (DO) levels are moderate (~55% air saturation), but can be found in areas of the Harbour where DO can range from 100% saturation to anoxia. Given that the water at their preferred depth is already hypoxic, we sought to investigate their response to further decreases in DO that may arise from potential increases in anthropogenic stress. We measured oxygen consumption, haematological parameters, tissue–enzyme capacity and heat shock protein (HSP) levels in skate exposed to 55% dissolved O2 saturation (control) and 20% dissolved O2 saturation (hypoxic) for 48 h. We conclude that the Maugean skate appears to be an oxyconformer, with a decrease in the rate of O2 consumption with increasing hypoxia. Increases in blood glucose and lactate at 20% O2 suggest that skate are relying more on anaerobic metabolism to tolerate periods of very low oxygen. Despite these metabolic shifts, there was no difference in HSP70 levels between groups, suggesting this short-term exposure did not elicit a cellular stress response. The metabolic state of the skate suggests that low oxygen stress for longer periods of time (i.e. >48 h) may not be tolerable and could potentially result in loss of habitat or shifts in their preferred habitat. Given its endemic distribution and limited life-history information, it will be critical to understand its tolerance to environmental challenges to create robust conservation strategies.

Short-term environmental variability in cold-water coral habitat at Viosca Knoll, Gulf of Mexico

2010 ◽  
Vol 57 (2) ◽  
pp. 199-212 ◽  
Author(s):  
Andrew J. Davies ◽  
Gerard C.A. Duineveld ◽  
Tjeerd C.E. van Weering ◽  
Furu Mienis ◽  
Andrea M. Quattrini ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Environmental Variability ◽  
Cold Water ◽  
Short Term ◽  
Water Coral

scholarly journals Environmental variability and acoustic signals: a multi-level approach in songbirds

2012 ◽  
Vol 8 (6) ◽  
pp. 928-931 ◽  
Author(s):  
Iliana Medina ◽  
Clinton D. Francis
Keyword(s):  
Sexual Selection ◽  
Environmental Variability ◽  
Extensive Study ◽  
Short Term ◽  
Intraindividual Variation ◽  
Habitat Features ◽  
Acoustic Adaptation ◽  
Song Complexity ◽  
Song Variation ◽  
Precipitation Seasonality

Among songbirds, growing evidence suggests that acoustic adaptation of song traits occurs in response to habitat features. Despite extensive study, most research supporting acoustic adaptation has only considered acoustic traits averaged for species or populations, overlooking intraindividual variation of song traits, which may facilitate effective communication in heterogeneous and variable environments. Fewer studies have explicitly incorporated sexual selection, which, if strong, may favour variation across environments. Here, we evaluate the prevalence of acoustic adaptation among 44 species of songbirds by determining how environmental variability and sexual selection intensity are associated with song variability (intraindividual and intraspecific) and short-term song complexity. We show that variability in precipitation can explain short-term song complexity among taxonomically diverse songbirds, and that precipitation seasonality and the intensity of sexual selection are related to intraindividual song variation. Our results link song complexity to environmental variability, something previously found for mockingbirds (Family Mimidae). Perhaps more importantly, our results illustrate that individual variation in song traits may be shaped by both environmental variability and strength of sexual selection.

scholarly journals Short-term variability in microbial food web dynamics in a shallow tidal estuary

2003 ◽  
Vol 31 ◽  
pp. 145-161 ◽  
Author(s):  
A Iriarte ◽  
I Madariaga ◽  
M Revilla ◽  
A Sarobe
Keyword(s):  
Food Web ◽  
Microbial Food Web ◽  
Short Term ◽  
Tidal Estuary ◽  
Food Web Dynamics ◽  
Short Term Variability

Spatial and temporal variation in amphibian metacommunity structure in Chiapas, Mexico

2014 ◽  
Vol 30 (6) ◽  
pp. 537-549 ◽  
Author(s):  
Leticia Margarita Ochoa-Ochoa ◽  
Robert James Whittaker
Keyword(s):  
Environmental Changes ◽  
Environmental Variability ◽  
Forest Disturbance ◽  
Rank Correlation ◽  
Environmental Data ◽  
Dynamic Responses ◽  
Temporary Ponds ◽  
Spatial And Temporal Variation ◽  
Short Term ◽  
Metacommunity Structure

Abstract:Amphibians are known to be sensitive to environmental change but their responses at the level of metacommunities to short-term environmental variability are poorly understood. We used field data from two protected areas, La Pera and Nahá (Chiapas, Mexico) to test for variation in metacommunity properties for two consecutive years (2009 and 2010). Amphibians and accompanying environmental data were recorded to a standardized protocol within each landscape, in four or five transects of 50 × 2-m per patch, for 30 and 31 patches, respectively. We found 23 species in La Pera and 30 in Nahá (21 species shared). Metacommunity structure was analysed using reciprocal averaging (RA) ordination by means of metrics for coherence, turnover and boundary clumping, with Spearman rank correlation used to examine relationships with environmental variables. The metacommunity structure varied differentially among the landscapes between years, being classed as quasi-Gleasonian in La Pera in both years, but Clementsian for Nahá in 2009 and Gleasonian for Nahá in 2010. In further illustration of variation between years, in 2009 the principal community gradient (RA axis 1) for La Pera was significantly positively correlated with altitude (r = 0.36), forest disturbance status (r = 0.78), mean canopy cover (r = 0.79) and mean litter depth (r = 0.67), while in 2010 it was correlated with latitude (r = 0.38), mean grass-layer height (r = 0.38), incidence of rainfall prior to sampling (r = 0.35) and presence of temporary ponds (r = 0.45). Our findings support the notion that amphibians respond to short-term environmental changes by individualistic movement within the landscape as well as via population dynamic responses.

scholarly journals Experimental evidence for foraminiferal calcification under anoxia

2014 ◽  
Vol 11 (3) ◽  
pp. 4669-4694 ◽  
Author(s):  
M. P. Nardelli ◽  
C. Barras ◽  
E. Metzger ◽  
A. Mouret ◽  
H. L. Filipsson ◽  
...  
Keyword(s):  
Anaerobic Metabolism ◽  
Environmental Variability ◽  
Adult Mortality ◽  
Short Term ◽  
Essential Information ◽  
Ample Evidence ◽  
Anoxic Conditions ◽  
Inhibition Of Growth ◽  
Foraminiferal Species ◽  
First Time

Abstract. Benthic foraminiferal tests are widely used for paleoceanographic reconstructions. There is ample evidence that foraminifera can live in anoxic sediments. For some species, this is explained by a switch to facultative anaerobic metabolism (i.e. denitrification). Here we show for the first time that adult specimens of three benthic foraminiferal species are not only able to survive but are also able to calcify in anoxic conditions, at various depths in the sediment, with and without nitrates. This demonstrates ongoing metabolic processes, even in micro-environments where denitrification is not possible. Earlier observations suggest that the disappearance of foraminiferal communities after prolonged anoxia is not due to instantaneous or strongly increased adult mortality. Here we show that it cannot be explained by an inhibition of growth through chamber addition either. Our observations of ongoing calcification under anoxic conditions means that geochemical proxy data obtained from benthic foraminifera in settings experiencing intermittent anoxia have to be reconsidered. The analysis of whole single specimens or of their successive chambers may provide essential information about short-term environmental variability and/or the causes of anoxia.

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