scholarly journals Tidal and seasonal forcing of dissolved nutrient fluxes in reef communities

2018 ◽  
Author(s):  
Renee K. Gruber ◽  
Ryan J. Lowe ◽  
James L. Falter
Keyword(s):  
Mass Transfer ◽  
Control Volume ◽  
Inorganic Nitrogen ◽  
Nutrient Supply ◽  
Nutrient Concentrations ◽  
Nutrient Fluxes ◽  
Uptake Rates ◽  
Reef Communities ◽  
Flow Speeds ◽  
Strong Control

Abstract. Benthic fluxes of dissolved nutrients in reef communities are controlled by oceanographic forcing including hydrodynamic regime and seasonal changes in oceanic nutrient supply. Up to a third of reefs worldwide can be characterised as having circulation that is tidally-driven, yet almost all previous research on reef nutrient fluxes has focused on systems with wave-driven circulation. Fluxes of dissolved nitrogen and phosphorus were measured on a strongly tide-dominated (spring range > 8 m) reef platform located in the Kimberley region of northwest Australia. A one-dimensional control volume approach was used, which combines continuous measurements of flow with modified Eulerian sampling of waters traversing the reef. Measured fluxes were compared to theoretical mass-transfer-limited uptake rates derived from flow speeds. Reef communities released a moderate amount of nitrate, potentially derived from the remineralization of phytoplankton and dissolved organic nitrogen. Nutrient concentrations and flow speeds varied between the major benthic communities (coral reef and seagrass), resulting in spatial variability in estimated nitrate uptake rates. Rapid changes in flow speed and water depth are key characteristics of tide-dominated reefs, which caused mass-transfer-limited nutrient uptake rates to vary by an order of magnitude on time scales of ~minutes–hours. Seasonal nutrient supply was also a strong control on reef mass-transfer-limited uptake rates, and increases in offshore dissolved inorganic nitrogen concentrations during the wet season caused an estimated twofold increase in uptake.

scholarly journals Tidal and seasonal forcing of dissolved nutrient fluxes in reef communities

2019 ◽  
Vol 16 (9) ◽  
pp. 1921-1935 ◽  
Author(s):  
Renee K. Gruber ◽  
Ryan J. Lowe ◽  
James L. Falter
Keyword(s):  
Mass Transfer ◽  
Nutrient Supply ◽  
Tidal Range ◽  
Nutrient Concentrations ◽  
Nutrient Fluxes ◽  
Flow Measurements ◽  
Uptake Rates ◽  
Reef Communities ◽  
Flow Speeds ◽  
Strong Control

Abstract. Benthic fluxes of dissolved nutrients in reef communities are controlled by oceanographic forcing, including local hydrodynamics and seasonal changes in oceanic nutrient supply. Up to a third of reefs worldwide can be characterized as having circulation that is predominantly tidally forced, yet almost all previous research on reef nutrient fluxes has focused on systems with wave-driven circulation. Fluxes of dissolved nitrogen and phosphorus were measured on a strongly tide-dominated reef platform with a spring tidal range exceeding 8 m. Nutrient fluxes were estimated using a one-dimensional control volume approach, combining flow measurements with modified Eulerian sampling of waters traversing the reef. Measured fluxes were compared to theoretical mass-transfer-limited uptake rates derived from flow speeds. Reef communities released 2.3 mmol m−2 d−1 of nitrate, potentially derived from the remineralization of phytoplankton and dissolved organic nitrogen. Nutrient concentrations and flow speeds varied between the major benthic communities (coral reef and seagrass), resulting in spatial variability in estimated nitrate uptake rates. Rapid changes in flow speed and water depth are key characteristics of tide-dominated reefs, which caused mass-transfer-limited nutrient uptake rates to vary by an order of magnitude on timescales of ∼ minutes–hours. Seasonal nutrient supply was also a strong control on reef mass-transfer-limited uptake rates, and increases in offshore dissolved inorganic nitrogen concentrations during the wet season caused an estimated twofold increase in uptake.

scholarly journals Nutrient Atmospheric Deposition on Utah Lake: A Comparison of Sampling and Analytical Methods

Hydrology ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 123
Author(s):  
Seth Michael Barrus ◽  
Gustavious Paul Williams ◽  
A. Woodruff Miller ◽  
M. Brett Borup ◽  
LaVere B. Merritt ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
Nutrient Loading ◽  
Inorganic Nitrogen ◽  
Dissolve Inorganic Nitrogen ◽  
Nutrient Concentrations ◽  
Nutrient Loads ◽  
Total Load ◽  
Significant Difference ◽  
Utah Lake ◽  
Collection Methods

We describe modified sampling and analysis methods to quantify nutrient atmospheric deposition (AD) and estimate Utah Lake nutrient loading. We address criticisms of previous published collection methods, specifically collection table height, screened buckets, and assumptions of AD spatial patterns. We generally follow National Atmospheric Deposition Program (NADP) recommendations but deviate to measure lake AD, which includes deposition from both local and long-range sources. The NADP guidelines are designed to eliminate local contributions to the extent possible, while lake AD loads should include local contributions. We collected side-by-side data with tables at 1 m (previous results) and 2 m (NADP guidelines) above the ground at two separate locations. We found no statistically significant difference between data collected at the different heights. Previous published work assumed AD rates would decrease rapidly from the shore. We collected data from the lake interior and show that AD rates do not significantly decline away from the shore. This demonstrates that AD loads should be estimated by using the available data and geostatistical methods even if all data are from shoreline stations. We evaluated screening collection buckets. Standard unscreened AD samples had up to 3-fold higher nutrient concentrations than screened AD collections. It is not clear which samples best represent lake AD rates, but we recommend the use of screens and placed screens on all sample buckets for the majority of the 2020 data to exclude insects and other larger objects such as leaves. We updated AD load estimates for Utah Lake. Previous published estimates computed total AD loads of 350 and 153 tons of total phosphorous (TP) and 460 and 505 tons of dissolve inorganic nitrogen (DIN) for 2017 and 2018, respectively. Using updated collection methods, we estimated 262 and 133 tons of TP and 1052 and 482 tons of DIN for 2019 and 2020, respectively. The 2020 results used screened samplers with lower AD rates, which resulted in significantly lower totals than 2019. We present these modified methods and use data and analysis to support the updated methods and assumptions to help guide other studies of nutrient AD on lakes and reservoirs. We show that AD nutrient loads can be a significant amount of the total load and should be included in load studies.

Nutrient pollution at the lower reaches of Mediterranean coastal rivers in Israel

2000 ◽  
Vol 42 (1-2) ◽  
pp. 147-152 ◽  
Author(s):  
B. Herut ◽  
N. Kress ◽  
H. Hornung
Keyword(s):  
Inorganic Nitrogen ◽  
Agricultural Runoff ◽  
Point Sources ◽  
Industrial Wastes ◽  
Nutrient Concentrations ◽  
Contamination Level ◽  
Nutrient Load ◽  
Nutrient Loads ◽  
Discharge Data ◽  
Coastal Rivers

This study represents the first attempt to evaluate the nutrient load introduced into the coastal waters by the rivers along the Mediterranean coast of Israel. Measurements of nutrient concentrations (phosphate, ammonium, nitrate, nitrite, silicic acid) at two or three stations along the lower river reaches (11 rivers) were carried out annually from 1990 up to 1998. Combining the nutrient concentrations with the monthly riverine discharges we assessed the nutrient load. In general, most of the coastal rivers contain high nutrient contamination level, compared to the criteria adopted by NOAA (USA) for coastal river estuaries. The high degree of contamination is attributed to extreme low natural flow combined with the discharge of domestic and industrial wastes, and with agriculture runoff. In terms of nutrient concentrations, the Kishon River is the most polluted, followed by the Soreq, Poleg and Alexander Rivers. The preliminary estimate is that the coastal rivers transport between ~2000 to 6000 tons of dissolved inorganic nitrogen (DIN) and between ~250–800 tons of dissolved inorganic phosphorus (DIP) to the sea. An additional 3500 and 3000 tons of DIN and DIP, respectively, are supplied through the Kishon River. The load of the Poleg River is unknown (no discharge data) but expected to be significant based on nutrient concentration measured. The total load of the coastal rivers constitutes a major component among the other land-base point sources such as the Gush Dan outfall. Our estimate probably represents minimal values, as it does not include diffused input of agricultural runoff nor the riverine particulate and dissolved organic nutrient loads (which are unknown).

scholarly journals Flood water quality and marine sediment and nutrient loads from the Tully and Murray catchments in north Queensland, Australia

2009 ◽  
Vol 60 (11) ◽  
pp. 1123 ◽  
Author(s):  
Jim Wallace ◽  
Lachlan Stewart ◽  
Aaron Hawdon ◽  
Rex Keen ◽  
Fazlul Karim ◽  
...  
Keyword(s):  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
Nutrient Concentrations ◽  
Large Contribution ◽  
Nutrient Loads ◽  
Nitrogen And Phosphorus ◽  
Annual Average ◽  
Nitrogen Loads ◽  
Flood Flows

Current estimates of sediment and nutrient loads from the Tully–Murray floodplain to the Great Barrier Reef lagoon are updated by taking explicit account of flood events. New estimates of flood discharge that include over-bank flows are combined with direct measurements of sediment and nutrient concentrations in flood waters to calculate the loads of sediment and nutrient delivered to the ocean during 13 floods that occurred between 2006 and 2008. Although absolute concentrations of sediment and nutrient were quite low, the large volume of water discharged during floods means that they make a large contribution (30–50%) to the marine load. By not accounting for flood flows correctly, previous estimates of the annual average discharge are 15% too low and annual loads of nitrogen and phosphorus are 47% and 32% too low respectively. However, because sediments may be source-limited, accounting for flood flows simply dilutes their concentration and the resulting annual average load is similar to that previously estimated. Flood waters also carry more dissolved organic nitrogen than dissolved inorganic nitrogen and this is the opposite of their concentrations in river water. Consequently, dissolved organic nitrogen loads to the ocean may be around twice those previously estimated from riverine data.

Utilization of nitrogen and carbon by phytoplankton in Moreton Bay, Australia

2000 ◽  
Vol 51 (7) ◽  
pp. 703 ◽  
Author(s):  
M. J. O'Donohue ◽  
P. M. Glibert ◽  
W. C. Dennison
Keyword(s):  
Water Temperature ◽  
Coastal Waters ◽  
Inorganic Nitrogen ◽  
Spatial Scales ◽  
Co2 Uptake ◽  
Phytoplankton Productivity ◽  
Moreton Bay ◽  
Uptake Rates ◽  
Temporal And Spatial ◽  
River Mouths

Water samples were collected within river mouths, at river plume sites and at well flushed ocean-influenced sites within Moreton Bay, a shallow subtropical embayment in south-eastern Queensland. Rates of inorganic nitrogen (NH+4 and NO-3) and carbon uptake were determined across temporal and spatial scales by use of 15N and 14C incorporation. Phytoplankton productivity, measured as CO2 uptake, was highest at the river mouths. Rates of NH+4 uptake exceeded rates of NO-3 uptake at all sites at all times. Relative preference indices demonstrated a consistent preference by phytoplankton for NH+4 uptake, and NH+4 uptake rates were higher at ocean-influenced sites than at river-mouth sites. Inorganic nutrient and chlorophyll a concentrations were highest at river mouths; however, the greatest NH+4 uptake occurred at the ocean-influenced sites, reflecting a greater dependence on ‘recycled’ N than on ‘new’ N. Biomass-independent NH+4 uptake increased with increasing water temperature; however, NO-3 uptake increased with decreasing water temperature, reflecting the lower temperature optimum for nitrate reductase. The range of NH+4 and NO-3 uptake rates was greater than ranges reported for other coastal waters, reflecting the strong temporal and spatial gradients within Moreton Bay. This trend of strong gradients in C and N dynamics from oligotrophic to river-influenced waters with seasonal flows is likely to exist in many tropical and subtropical coastal waters of Australia.

scholarly journals Influences of Nutrient Sources on the Alternation of Nutrient Limitations and Phytoplankton Community in Jiaozhou Bay, Southern Yellow Sea of China

2020 ◽  
Vol 12 (6) ◽  
pp. 2224
Author(s):  
Jie Shi ◽  
Qian Leng ◽  
Junying Zhu ◽  
Huiwang Gao ◽  
Xinyu Guo ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
Phytoplankton Community ◽  
Inorganic Nitrogen ◽  
Marine Ecosystem ◽  
Jiaozhou Bay ◽  
Nutrient Concentrations ◽  
River Input ◽  
Aquaculture Wastewater ◽  
The 1960S ◽  
Yellow Sea Of China

A marine ecosystem box model was developed to reproduce the seasonal variations nutrient concentrations and phytoplankton biomasses in Jiaozhou Bay (JZB) of China. Then, by removing each of the external sources of nutrients (river input, aquaculture, wastewater discharge, and atmospheric deposition) in the model calculation, we quantitatively estimated its influences on nutrient structure and the phytoplankton community. Removing the river input of nutrients enhanced silicate (SIL) limitation to diatoms (DIA) and decreased the ratio of DIA to flagellates (FLA); removing the aquaculture input of nutrients decreased FLA biomass because it provided less dissolved inorganic nitrogen (DIN) but more dissolved inorganic phosphate (DIP) as compared to the Redfield ratio; removing the wastewater input of nutrients changed the DIN concentration dramatically, but had a relatively weaker impact on the phytoplankton community than removing the aquaculture input; removing atmospheric deposition had a negligible influence on the model results. Based on these results, we suppose that the change in the external nutrients sources in the past several decades can explain the long-term variations in nutrient structure and phytoplankton community. Actually, the simulations for the 1960s, 1980s, and 2000s in JZB demonstrated the shift of limiting nutrients from DIP to SIL. A reasonable scenario for this is the decrease in riverine SIL and increase in DIP from aquaculture that has reduced DIA biomass, promoted the growth of FLA, and led to the miniaturization of the phytoplankton.

scholarly journals Technical Note: A comparison of two empirical approaches to estimate in-stream net nutrient uptake

2011 ◽  
Vol 8 (4) ◽  
pp. 875-882 ◽  
Author(s):  
D. von Schiller ◽  
S. Bernal ◽  
E. Martí
Keyword(s):  
Mass Balance ◽  
Nutrient Uptake ◽  
Nutrient Concentrations ◽  
Nutrient Loads ◽  
Data Set ◽  
Advantages And Disadvantages ◽  
Balance Approach ◽  
Uptake Rates ◽  
Empirical Approaches ◽  
Mass Balance Approach

Abstract. To establish the relevance of in-stream processes on nutrient export at catchment scale it is important to accurately estimate whole-reach net nutrient uptake rates that consider both uptake and release processes. Two empirical approaches have been used in the literature to estimate these rates: (a) the mass balance approach, which considers changes in ambient nutrient loads corrected by groundwater inputs between two stream locations separated by a certain distance, and (b) the spiralling approach, which is based on the patterns of longitudinal variation in ambient nutrient concentrations along a reach following the nutrient spiralling concept. In this study, we compared the estimates of in-stream net nutrient uptake rates of nitrate (NO3) and ammonium (NH4) and the associated uncertainty obtained with these two approaches at different ambient conditions using a data set of monthly samplings in two contrasting stream reaches during two hydrological years. Overall, the rates calculated with the mass balance approach tended to be higher than those calculated with the spiralling approach only at high ambient nitrogen (N) concentrations. Uncertainty associated with these estimates also differed between both approaches, especially for NH4 due to the general lack of significant longitudinal patterns in concentration. The advantages and disadvantages of each of the approaches are discussed.

scholarly journals Phytoplankton Biomass Dynamics in Tropical Coastal Waters of Jakarta Bay, Indonesia in the Period between 2001 and 2019

2020 ◽  
Vol 8 (9) ◽  
pp. 674 ◽  
Author(s):  
Ario Damar ◽  
Franciscus Colijn ◽  
Karl-Juergen Hesse ◽  
Luky Adrianto ◽  
Yonvitner ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Algal Blooms ◽  
Temporal Dynamics ◽  
Inorganic Nitrogen ◽  
Outer Part ◽  
Middle Part ◽  
Nutrient Concentrations ◽  
Marine Biota ◽  
Chl A ◽  
Hypoxic Conditions

A study of nutrients, underwater light dynamics, and their correlation with phytoplankton biomass was conducted in the tropical estuary of Jakarta Bay, Indonesia, in the dry season during the period from 2001 to 2019. This study analyzed the spatial and temporal dynamics of phytoplankton biomass and its correlation with phytoplankton biomass. There was significant increase in nutrient concentration in Jakarta Bay, with annual means of 27.97 µM dissolved inorganic nitrogen (DIN) and 11.31 µM phosphates in 2001, increasing to 88.99 µM DIN and 25.92 µM phosphates in 2019. Increased mean nutrient concentrations were accompanied by increased mean phytoplankton biomass, from 15.81 µg Chl-a L−1 in 2001 to 21.31 µg Chl-a L−1 in 2019. The eutrophication status of Jakarta Bay waters was calculated using the Tropical Index for Marine Systems eutrophication index, which showed increased areas of hyper-eutrophic and eutrophic zones, while the mesotrophic area decreased. The hyper-eutrophic zone dominated the areas around river mouths and the inner part of the bay, while eutrophic status was observed in the middle part of the bay and mesotrophic status was found in the outer part of the bay. The area of hyper-eutrophic water increased 1.5-fold, from 75.1 km2 in 2001 to 114.0 km2 in 2019. Increasing eutrophication of the bay has had negative ecological consequences including algal blooms, hypoxic conditions, and mass mortality of marine biota, and it urgently requires remediation.

Nutrients in Australian tropical rivers: changes with agricultural development and implications for receiving environments

2005 ◽  
Vol 56 (3) ◽  
pp. 279 ◽  
Author(s):  
Jon E. Brodie ◽  
Alan W. Mitchell
Keyword(s):  
Agricultural Development ◽  
Nutrient Dynamics ◽  
Inorganic Nitrogen ◽  
Nutrient Concentrations ◽  
Tropical Rivers ◽  
Nutrient Inputs ◽  
Material Transport ◽  
Nitrogen And Phosphorus ◽  
North East ◽  
The North

In tropical Australia, intensive studies of river suspended sediment (SS) and nutrient dynamics have been restricted to streams on the north-east coast between the Fitzroy and Normanby Rivers (Queensland), Magela Creek/East Alligator River (Northern Territory) and the Ord River (Western Australia). Historical conditions in these rivers were probably characterised by low–moderate SS concentrations and low concentrations of dissolved inorganic nitrogen and phosphorus in flow events. Introduction of agriculture has transformed SS and nutrient dynamics. Grazing has led to soil erosion and increased SS and particulate nutrient concentrations and fluxes in event flows. Fertilised cropping has increased nutrient inputs to catchments, where it forms a substantial proportion of the catchment area. Consequently, both particulate and dissolved inorganic nutrient concentrations and fluxes have increased. Australian tropical rivers have episodic flows, with most material transport occurring during large flow events. The restricted period of these highly energetic flows means little trapping of materials in waterways occurs. Loads are transported efficiently downstream and processes such as denitrification and in-channel sedimentation may be of limited importance. Owing to excessive nutrient inputs associated with agriculture, a number of northern freshwater, estuarine and coastal ecosystems are now eutrophic. Continued development, especially fertilised cropping, without adequate management of nutrient losses is likely to exacerbate these problems.

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