Nutrient Enrichment Studies in a Coastal Plain Estuary: Phytoplankton Growth in Large-Scale, Continuous Cultures

1986 ◽  
Vol 43 (2) ◽  
pp. 397-406 ◽  
Author(s):  
Christopher F. D'Elia ◽  
James G. Sanders ◽  
Walter R. Boynton
Keyword(s):  
Nutrient Enrichment ◽  
Large Scale ◽  
River Flow ◽  
River Estuary ◽  
Late Summer ◽  
Phytoplankton Growth ◽  
Low Flow ◽  
Late Winter ◽  
Continuous Cultures ◽  
Natural Phytoplankton

The response of phytoplanktonic growth to experimental nutrient addition in a tributary of the Chesapeake Bay estuary varied with season and nutrient availability. In bioassay experiments employing outdoor 0.5-m3 continuous cultures freshly inoculated with natural phytoplankton from the Patuxent River estuary, supplements of N, either as ammonium or nitrate, enhanced growth greatly during the low-flow, late-summer season — a period when N:P ratios of dissolved inorganic nutrient standing stocks are characteristically below 5:1 (by atoms). Growth response to N addition was very rapid (1 d after the start of an experiment), implying that phytoplankton in the bioassay were N limited when removed from the estuary. PO43− addition enhanced phytoplankton growth during the late-winter, high-flow season, when N: P ratios (as previous) typically exceed 90:1 (by atoms), but the response lagged enrichment by at least 4 d and biomass levels achieved in these cultures were less than one third of those achieved in the N-enriched cultures during the late summer. The great seasonal variability in river flow, nutrient regimes, and the response of natural phytoplankton assemblages to nutrient enrichment in the Patuxent, and similar estuaries, suggest that management strategies to improve "water quality" will need to consider N as well as P additions.

Sources of Chlorophenolic Compounds to the Fraser River Estuary

1988 ◽  
Vol 23 (1) ◽  
pp. 55-68 ◽  
Author(s):  
J. H. Carey ◽  
J. H. Hart
Keyword(s):  
River Flow ◽  
River Estuary ◽  
Low Flow ◽  
Fraser River ◽  
Pulp Mills ◽  
Flow Conditions ◽  
Downstream Site ◽  
Upstream Site ◽  
The North ◽  
Main River

Abstract The identity and concentrations of chlorophenolic compounds in the Fraser River estuary were determined under conditions of high and low river flow at three sites: a site upstream from the trifurcation and at downstream sites for each main river arm. Major chlorophenolics present under both flow regimes were 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), pentachlorophenol (PCP), tetrachloroguaiacol (TeCG) and a compound tentatively identified as 3,4,5-trichloroguaiacol (3,4,5-TCG). Under high flow conditions, concentrations of the guaiacols were higher than any of the Chlorophenols and concentrations of all five chlorophenolics appeared to correlate. Under low flow conditions, concentrations of chloroguaiacols were higher than Chlorophenols at the upstream site and at the downstream site on the Main Arm, whereas at the downstream site on the North Arm, concentrations of 2,3,4,6-TeCP and PCP were higher than the chloroguaiacols in some samples. Overall, the results indicate that pulp mills upstream from the estuary are important sources of chlorophenolics to the estuary under all flow conditions. Additional episodic inputs of 2,3,4,6-TeCP and PCP from lumber mills occur along the North Arm. When these inputs occur, they can cause the concentrations of Chlorophenols in the North Arm to exceed provisional objectives. If chloroguaiacols are included as part of the objective, concentrations of total chlorophenolics in water entering the estuary can approach and exceed these objectives, especially under low flow conditions.

Identifying resuspended sediment in an estuary using the 228Th/232Th activity ratio: the fate of lagoon sediment in the Bega River estuary, Australia

2000 ◽  
Vol 51 (7) ◽  
pp. 659 ◽  
Author(s):  
Gary J. Hancock
Keyword(s):  
Suspended Sediment ◽  
River Flow ◽  
Activity Ratio ◽  
Sediment Resuspension ◽  
River Estuary ◽  
Low Flow ◽  
Eastern Australia ◽  
Lagoon Sediment ◽  
Thorium Series ◽  
High River Flow

Thorium-series nuclides (228Th and 232Th) have been used to identify resuspended sediment in the Bega River estuary, south-eastern Australia. A non-conservative increase in concentration of suspended sediment of water in the vicinity of mid-estuary back-flow lagoons was associated with a decrease in the 228Th/232Th activity ratio (AR) of the suspended sediment. The lagoon sediment is characterized by a low estuarine 228Th/232Th signature, distinguishing it from freshwater suspended sediment recently delivered to the estuary, and identifying it as the likely source of the additional suspended sediment. Sediment-core 210Pb profiles show that the lagoons are accumulating sediment, presumably during high river-flow events. However this study indicates that during intervening periods of low flow, 40% of sediment deposited in the lagoons is subsequently resuspended and exported to the lower estuary, and possibly to the ocean. The utility of the 228Th/232Th AR to quantify sediment resuspension in estuaries is likely to be estuary-dependent, and is controlled by the extent of scavenging of dissolved 228Th by suspended particles.

scholarly journals Variability of low flow magnitudes in the Upper Colorado River Basin: identifying trends and relative role of large-scale climate dynamics

2014 ◽  
Vol 11 (7) ◽  
pp. 8779-8802 ◽  
Author(s):  
M. Pournasiri Poshtiri ◽  
I. Pal
Keyword(s):  
River Basin ◽  
Large Scale ◽  
River Flow ◽  
Colorado River ◽  
Colorado River Basin ◽  
Low Flow ◽  
Anthropogenic Factors ◽  
Relative Role ◽  
Water Abstraction

Abstract. Low flow magnitude in a head water basin is important for planners because minimum available amount of water in a given time period often leads to concerns regarding serious repercussions, in both up and downstream regions. This is a common scenario in arid region like Colorado River basin located in the southwestern US. Low flow variability in Colorado River is due to complex interactions between several natural and anthropogenic factors; but we aim to identify the relative role of climate on varying low flow magnitudes at different spatial locations. The research questions we aim to answer are: Is there a systematic variability in water availability during the driest time of a year or season? How does that vary across locations and is there a link between large-scale climate and low flow variations? Towards that aim we select 17 stream gauge locations, which are identified as "undisturbed" meaning that these stations represent near-natural river flow regimes in the headwater region of Colorado River, which provides a useful resource for assessment of climate and hydrology associations without the confounding factor of major direct (e.g. water abstraction) or indirect (e.g. land-use change) human modification of flows. A detailed diagnostic analysis gives us fair understanding on the variability of low flow magnitude that is explained by climate. We also present spatial heterogeneity of hydro-climatological linkages that is important for suitable adaptive management measures.

scholarly journals Survival and migration of rock ptarmigan in central Scandinavia

2019 ◽  
Author(s):  
Erlend B. Nilsen ◽  
Pål Fossland Moa ◽  
Henrik Brøseth ◽  
Hans Chr. Pedersen ◽  
Bjørn Roar Hagen
Keyword(s):  
Climate Change ◽  
Breeding Season ◽  
Large Scale ◽  
Late Summer ◽  
Late Winter ◽  
Rock Ptarmigan ◽  
The Mean ◽  
Lagopus Muta ◽  
And Migration

In a world undergoing massive declines in the distribution and abundance of many wildlife species, documenting basic ecological characteristics is often needed to be able to understand and potentially mitigate current and future pressures. Species living in alpine areas might be particularly vulnerable to climate change, in part because they are less likely to be able to migrate to new suitable areas. Here we report from a two year case study of rock ptarmigan (Lagopus muta) in central Scandinavia. Ptarmigan were captured in winter (n=84), and fitted with radio collars. We estimated the natural survival from mid-winter to late summer to be 0.55 (SE: 0.07), with no distinct differences between juveniles and adults, sex, or between the two years. Natural survival through late winter (February – April) was estimated at 0.77 (SE: 0.05), survival trough breeding season May-July at 0.65 (SE: 0.08), and harvest mortality through the February winter harvest at 9% (SE: 3%). Moreover, we documented large scale movement from the wintering grounds before the breeding season in the spring. The longest recorded movement was 79.5 km, and the mean distance from the capture site for birds still in the sample in May-July was 20.3 (SD: 18) km. We discuss the implications of the results in terms of ongoing climate change.

scholarly journals Large-Scale Climatic Controls on New England River Flow

2007 ◽  
Vol 8 (3) ◽  
pp. 367-379 ◽  
Author(s):  
Daniel G. Kingston ◽  
Glenn R. McGregor ◽  
David M. Hannah ◽  
Damian M. Lawler
Keyword(s):  
New England ◽  
Air Temperature ◽  
North Atlantic ◽  
Large Scale ◽  
River Flow ◽  
Positive Association ◽  
Low Flow ◽  
Temperature Pattern ◽  
The North ◽  
The North Atlantic

Abstract Understanding atmospheric drivers of river flow variability necessitates clear knowledge of the process chain linking climate and hydrology, yet the nature of such linkages remains poorly understood for the New England region of the northeastern United States. This research gap is addressed through a composite analysis of large-scale climatic controls on monthly high and low river flow in New England for 1958–2001, based on 40-yr ECMWF Re-Analysis (ERA-40) data. Analysis is focused on climate fields at the North Atlantic spatial scale, with particular attention given to the influence of the North Atlantic Oscillation (NAO). High (low) river flow is shown to be characterized by greater (lower) geopotential height throughout the year, and from December to April, higher (lower) temperature. Wind speed is inversely associated with river flow in all months, with wind direction more southerly (northerly) under high (low) flow situations. Relative vorticity differences reveal more cyclonic circulation centered downwind of New England under low river flow conditions (compared to high flow) from December to April. Reversal of river flow associations with temperature and vorticity in May are linked to snowmelt dynamics. Although cursory analysis suggests a positive association between the NAO and New England river flow, closer inspection reveals this to be less straightforward. River flow is more closely linked to the East Coast trough (rather than the Icelandic low and Azores high), while air temperature anomalies resemble the NAO–sea surface temperature rather than NAO–air temperature pattern.

A large-scale hydroclimatological perspective on western European river flow regimes

2012 ◽  
Vol 44 (5) ◽  
pp. 809-833 ◽  
Author(s):  
Donna Wilson ◽  
David M. Hannah ◽  
Glenn R. McGregor
Keyword(s):  
Large Scale ◽  
Western Europe ◽  
River Flow ◽  
Flow Regimes ◽  
Climatic Conditions ◽  
Low Flow ◽  
Annual Rainfall ◽  
Time Variability ◽  
Runoff Generation

A novel flow regime classification scheme was applied to 141 river basins across western Europe, providing more robust analysis of space–time variability in regimes and their driving hydroclimatological processes. Regime shape (timing) and magnitude (size) were classified to regionalise long-term average flow regimes and to quantify year-to-year variation in regimes for each basin. Six long-term regime shape regions identified differences in seasonality related to latitude and altitude. Five long-term magnitude regions were linked to location plus average annual rainfall. Spatial distribution of long-term regimes reflected dominant climate and runoff generation processes. Regions were used to structure analysis of (relative) inter-annual regime dynamics. Six shape and five magnitude inter-annual regimes were identified; and regime stability (switching) assessed at pan-European, regional and basin scales. In some years, certain regime types were more prevalent, but never totally dominant. Regime shape was more stable at higher altitude due to buffering by frozen water storage-release (cf. more variable rainfall-runoff at lower altitudes). The lower inter-annual magnitude regimes persisted across larger domains (cf. higher magnitude) due to the more widespread climatic conditions generating low flow. Notably, there was limited spatio-temporal correspondence between regime shape and magnitude, suggesting variations in one attribute cannot be used to infer the other.

Shipworm (Bankia setacea) activity within the Port of Everett and the Snohomish River Estuary: Defining the problem

1995 ◽  
Vol 71 (2) ◽  
pp. 186-191 ◽  
Author(s):  
R. I. Gara ◽  
F. E. Greulich
Keyword(s):  
Saltwater Intrusion ◽  
River Flow ◽  
Salt Water ◽  
Larval Settlement ◽  
River Estuary ◽  
Late Summer ◽  
Salt Water Intrusion ◽  
Freshwater Flow ◽  
Year 2000 ◽  
And Storage

Log rafts stored in the Snohomish River estuary, a facility maintained by the Port of Everett, Washington, were infested by shipworms (Bankia setacea) during 1987. Studies were done to identify when the log rafts were infested, establish relationships between estuarine conditions and shipworm attack, and examine the potential for future infestations. The first two objectives were studied by retracing in time and place the patterns of log raft movements and by developing a salt water intrusion model. The last objective was met by developing a river flow predictive model. The timing of log raft movements and storage during periods of low river flow and high B. setacea larval settlement were responsible for the shipworm infestations. In particular, uncommonly low river flow in 1987 created estuarine salt water conditions favorable for shipworm activity in the normally safe log storage areas. If the late summer trend in freshwater flow reduction observed since 1963 continues, then by the year 2000, the average monthly flow during the period of maximum shipworm settlement will drop by about a third from current flow levels. Under these conditions, saltwater intrusion and B. setacea damage will become more common within the estuary. Key words: shipworms, log rafts, log storage, estuarine conditions, saltwater intrusion, river flow, predictive models

scholarly journals Seasonal population dynamics of Octopus vulgaris in the eastern Mediterranean

2006 ◽  
Vol 63 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Stelios Katsanevakis ◽  
George Verriopoulos
Keyword(s):  
Eastern Mediterranean ◽  
Late Summer ◽  
Main Peak ◽  
Octopus Vulgaris ◽  
Late Winter ◽  
Visual Census ◽  
The Common ◽  
Specific Growth Rates ◽  
Seasonal Population ◽  
Seasonal Population Dynamics

Abstract The population density of Octopus vulgaris was measured by visual census with scuba diving in coastal areas in Greece (eastern Mediterranean). A time-variant, stage-classified, matrix population model was developed to interpret the seasonal variation of octopus stage densities and to estimate several life cycle parameters. An annual and a semi-annual periodic cycle were found in the stage densities. A main peak of benthic settlement was observed during summer and a secondary, irregular one during late autumn. Two spawning peaks were estimated, a main one during late winter–spring and a secondary one during late summer–early autumn. More than 50% of the just-settled individuals will eventually die after 3 months. Mortality rate declines, as individuals grow larger, reaches a minimum approximately 6 months after settlement, and then grows again probably because of terminal spawning. The life expectancy of recently settled individuals (<50 g) during their summer peak is approximately 5 months. The lifespan of the common octopus is estimated to be between 12 and 15 months. The octopuses' mean specific growth rates (±s.d.) in their natural environment were 1.61 ± 0.30 d−1 for 50–200 g individuals and 1.19 ± 0.31 d−1 for 200–500 g individuals.

Late-summer carbon fluxes from Canadian forests and peatlands along an east–west continental transect

2006 ◽  
Vol 36 (3) ◽  
pp. 783-800 ◽  
Author(s):  
Carole Coursolle ◽  
Hank A Margolis ◽  
Alan G Barr ◽  
T Andrew Black ◽  
Brian D Amiro ◽  
...  
Keyword(s):  
Large Scale ◽  
Ecosystem Respiration ◽  
Late Summer ◽  
Ecosystem Productivity ◽  
Diurnal Courses ◽  
Continental Scale ◽  
Young Forest ◽  
C Cycle ◽  
Use Efficiency ◽  
East West

Net ecosystem productivity (NEP) during August 2003 was measured by using eddy covariance above 17 forest and 3 peatland sites along an east–west continental-scale transect in Canada. Measured sites included recently disturbed stands, young forest stands, intermediate-aged conifer stands, mature deciduous stands, mature conifer stands, fens, and an open shrub bog. Diurnal courses of NEP showed strong coherence within the different ecosystem categories. Recently disturbed sites showed the weakest diurnal cycle; and intermediate-aged conifers, the strongest. The western treed fen had a more pronounced diurnal pattern than the eastern shrub bog or the Saskatchewan patterned fen. All but three sites were clearly afternoon C sinks. Ecosystem respiration was highest for the young fire sites. The intermediate-aged conifer sites had the highest maximum NEP (NEPmax) and gross ecosystem productivity (GEPmax), attaining rates that would be consistent with the presence of a strong terrestrial C sink in regions where these types of forest are common. These results support the idea that large-scale C cycle modeling activities would benefit from information on the age-class distribution and disturbance types within larger grid cells. Light use efficiency followed a pattern similar to that of NEPmax and GEPmax. Four of the five recently disturbed sites and all three of the peatland sites had low water use efficiencies.

scholarly journals Microbial Diversity Analysis of Sediment from Nakdong River Estuary in the Republic of Korea Using 16S rRNA Gene Amplicon Sequencing

2018 ◽  
Vol 7 (14) ◽  
Author(s):  
Kyunghoi Kim
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Microbial Diversity ◽  
Large Scale ◽  
Sediment Quality ◽  
River Estuary ◽  
Republic Of Korea ◽  
Rrna Gene ◽  
Nakdong River ◽  
The Republic

Deterioration of sediment quality has been found in the Nakdong River Estuary after large-scale reclamations. Here, I report microbial diversity in sediments of Nakdong River Estuary in the Republic of Korea based on 16S rRNA gene sequencing by next-generation sequencing (NGS) techniques.

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