Multiple Dating of a Freeze Core from Lake 227, an Experimentally Fertilized Lake with Varved Sediments

A freeze core taken from Experimental Lakes Area Lake 227 in 1988 contained 321 rhythmically paired, dark and light laminations in the upper 60.7 cm. Tape peels revealed cyclic, seasonal abundance peaks in organic and inorganic remains, which suggested that the couplets are varves. However, comparison between varve chronology and 22 yr of experimental changes in phosphorus (P) and nitrogen (N) loading and their influence on the planktonic community confirmed that the most recent varve-year estimates were 5 or 6 yr too old; this was caused by irregular sedimentation and multiple algal blooms resulting from experimental fertilization since 1969, and indistinct laminations that hampered precise couplet identification and separation. Dated horizons determined from biostratigraphic markers were used to generate compatible profiles between 1-cm slices of Lake 227 137Cs flux and reference fallout records. Nutrient concentration profiles were less helpful, as increases in carbon, N, and, P were gradual and no distinct horizon was identified as a clear marker of eutrophication. Long-term assessment of the varve chronology using 210Pb was hindered by experimental additions of 226Ra to the lake in 1970, although similar sedimentation rates from varve years 1860–1934 suggested that the varve and the deep part of the 210Pb chronologies were comparable.

Download Full-text

Long-term influence of climate and experimental eutrophication regimes on phytoplankton blooms

10.1101/658799 ◽

2019 ◽

Author(s):

Kateri R. Salk ◽

Jason J. Venkiteswaran ◽

Raoul-Marie Couture ◽

Scott N. Higgins ◽

Michael J. Paterson ◽

...

Keyword(s):

Climate Change ◽

Algal Blooms ◽

Nutrient Loading ◽

Data Availability ◽

Change Scenario ◽

Nutrient Loads ◽

Phytoplankton Blooms ◽

Experimental Lakes Area ◽

Link Type

AbstractPhytoplankton blooms respond to multiple drivers, including climate change and nutrient loading. Here we examine a long-term dataset from Lake 227, a site exposed to a fertilization experiment (1969–present). Changes in nitrogen:phosphorus loading ratios (high N:P, low N:P, P-only) did not impact mean annual biomass, but blooms exhibited substantial inter- and intra-annual variability. We used a process-oriented lake model, MyLake, to successfully reproduce lake physics over 48 years and test if a P-limited model structure predicted blooms. The timing and magnitude of blooms was reproduced during the P-only period but not for the high and low N:P periods, perhaps due to N acquisition pathways not currently included in the model. A model scenario with no experimental fertilization confirmed P loading is the major driver of blooms, while a scenario that removed climate-driven temperature trends showed that increased spring temperatures have exacerbated blooms beyond the effects of fertilization alone.Significance StatementHarmful algal blooms and eutrophication are key water quality issues worldwide. Managing algal blooms is often difficult because multiple drivers, such as climate change and nutrient loading, act concurrently and potentially synergistically. Long-term datasets and simulation models allow us to parse the effects of interacting drivers of blooms. The performance of our model depended on the ratio of nitrogen to phosphorus inputs, suggesting that complex biological dynamics control blooms under variable nutrient loads. We found that blooms were dampened under a “no climate change” scenario, suggesting that the interaction of nutrient loading and increased temperature intensifies blooms. Our results highlight successes and gaps in our ability to model blooms, helping to establish future management recommendations.Data Availability StatementData and metadata will be made available in a GitHub repository (https://github.com/biogeochemistry/Lake-227). Upon manuscript acceptance, the repository will be made publicly available and a DOI will be provided. We request that data users contact the Experimental Lakes Area directly, per their data use policy (http://www.iisd.org/ela/wp-content/uploads/2016/04/Data-Terms-And-Conditions.pdf).

Download Full-text

National coastal management challenges and needs

Shore & Beach ◽

10.34237/1008843 ◽

2020 ◽

pp. 34-43

Author(s):

Nicole Elko ◽

Tiffany Roberts Briggs

Keyword(s):

Coastal Management ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

Local Community ◽

Extreme Event ◽

Technical Information ◽

Interdisciplinary Approach ◽

Beach Erosion ◽

The U.S

In partnership with the U.S. Geological Survey Coastal and Marine Hazards and Resources Program (USGS CMHRP) and the U.S. Coastal Research Program (USCRP), the American Shore and Beach Preservation Association (ASBPA) has identified coastal stakeholders’ top coastal management challenges. Informed by two annual surveys, a multiple-choice online poll was conducted in 2019 to evaluate stakeholders’ most pressing problems and needs, including those they felt most ill-equipped to deal with in their day-to-day duties and which tools they most need to address these challenges. The survey also explored where users find technical information and what is missing. From these results, USGS CMHRP, USCRP, ASBPA, and other partners aim to identify research needs that will inform appropriate investments in useful science, tools, and resources to address today’s most pressing coastal challenges. The 15-question survey yielded 134 complete responses with an 80% completion rate from coastal stakeholders such as local community representatives and their industry consultants, state and federal agency representatives, and academics. Respondents from the East, Gulf, West, and Great Lakes coasts, as well as Alaska and Hawaii, were represented. Overall, the prioritized coastal management challenges identified by the survey were: Deteriorating ecosystems leading to reduced (environmental, recreational, economic, storm buffer) functionality, Increasing storminess due to climate change (i.e. more frequent and intense impacts), Coastal flooding, both Sea level rise and associated flooding (e.g. nuisance flooding, king tides), and Combined effects of rainfall and surge on urban flooding (i.e. episodic, short-term), Chronic beach erosion (i.e. high/increasing long-term erosion rates), and Coastal water quality, including harmful algal blooms (e.g. red tide, sargassum). A careful, systematic, and interdisciplinary approach should direct efforts to identify specific research needed to tackle these challenges. A notable shift in priorities from erosion to water-related challenges was recorded from respondents with organizations initially formed for beachfront management. In addition, affiliation-specific and regional responses varied, such as Floridians concern more with harmful algal blooms than any other human and ecosystem health related challenge. The most common need for additional coastal management tools and strategies related to adaptive coastal management to maintain community resilience and continuous storm barriers (dunes, structures), as the top long-term and extreme event needs, respectively. In response to questions about missing information that agencies can provide, respondents frequently mentioned up-to-date data on coastal systems and solutions to challenges as more important than additional tools.

Download Full-text

Impact of Dursban and Abate on Microbial Numbers and Some Chemical Properties of Standing Ponds

Water Quality Research Journal ◽

10.2166/wqrj.1975.006 ◽

1975 ◽

Vol 10 (1) ◽

pp. 33-41 ◽

Cited By ~ 3

Author(s):

J. Butcher ◽

M. Boyer ◽

CD. Fowle

Keyword(s):

Carbon Dioxide ◽

Active Ingredient ◽

Algal Blooms ◽

Chemical Properties ◽

Total Carbon ◽

Dissolved Carbon ◽

Photosynthetic Productivity ◽

Dissolved Carbon Dioxide ◽

Microbial Numbers

Abstract Eleven small ponds, lined with polyethylene, were used to assess the consequences of applications of *DursbanR at 0.004, 0.030, 0.100 and 1.000 ppm and AbateR at 0.025 and 0.100 ppm active ingredient. The treated ponds showed a more pronounced long-term increase in pH and dissolved oxygen and decreasing total and dissolved carbon dioxide in comparison with untreated ponds. Algal blooms were of longer duration in treated ponds than in controls. Total photosynthetic productivity was higher in treated ponds but bacterial numbers did not change significantly. Photosynthetic productivity was estimated by following the changes in total carbon dioxide.

Download Full-text

Nitrogen cycling in Sandusky Bay, Lake Erie: oscillations between strong and weak export and implications for harmful algal blooms

Biogeosciences ◽

10.5194/bg-15-2891-2018 ◽

2018 ◽

Vol 15 (9) ◽

pp. 2891-2907 ◽

Cited By ~ 14

Author(s):

Kateri R. Salk ◽

George S. Bullerjahn ◽

Robert Michael L. McKay ◽

Justin D. Chaffin ◽

Nathaniel E. Ostrom

Keyword(s):

Harmful Algal Blooms ◽

Algal Blooms ◽

Lake Erie ◽

N Uptake ◽

N Fixation ◽

N Budget ◽

N2o Production ◽

N Removal ◽

Uptake Rates ◽

N Loading

Abstract. Recent global water quality crises point to an urgent need for greater understanding of cyanobacterial harmful algal blooms (cHABs) and their drivers. Nearshore areas of Lake Erie such as Sandusky Bay may become seasonally limited by nitrogen (N) and are characterized by distinct cHAB compositions (i.e., Planktothrix over Microcystis). This study investigated phytoplankton N uptake pathways, determined drivers of N depletion, and characterized the N budget in Sandusky Bay. Nitrate (NO3-) and ammonium (NH4+) uptake, N fixation, and N removal processes were quantified by stable isotopic approaches. Dissimilatory N reduction was a relatively modest N sink, with denitrification, anammox, and N2O production accounting for 84, 14, and 2 % of sediment N removal, respectively. Phytoplankton assimilation was the dominant N uptake mechanism, and NO3- uptake rates were higher than NH4+ uptake rates. Riverine N loading was sometimes insufficient to meet assimilatory and dissimilatory demands, but N fixation alleviated this deficit. N fixation made up 23.7–85.4 % of total phytoplankton N acquisition and indirectly supports Planktothrix blooms. However, N fixation rates were surprisingly uncorrelated with NO3- or NH4+ concentrations. Owing to temporal separation in sources and sinks of N to Lake Erie, Sandusky Bay oscillates between a conduit and a filter of downstream N loading to Lake Erie, delivering extensively recycled forms of N during periods of low export. Drowned river mouths such as Sandusky Bay are mediators of downstream N loading, but climate-change-induced increases in precipitation and N loading will likely intensify N export from these systems.

Download Full-text

A long-term multi-proxy record of varved sediments highlights climate-induced mixing-regime shift in a large hard-water lake ~5000 years ago

Journal of Limnology ◽

10.4081/jlimnol.2014.907 ◽

2014 ◽

Vol 73 (2) ◽

Cited By ~ 3

Author(s):

Walter Finsinger ◽

Thierry Fonville ◽

Emiliya Kirilova ◽

Andrea Lami ◽

Piero Guilizzoni ◽

...

Keyword(s):

Regime Shift ◽

Hard Water ◽

Proxy Record ◽

Varved Sediments ◽

Water Lake ◽

Mixing Regime

Download Full-text

Application of 210Pb-derived sedimentation rates and dinoflagellate cyst analyses in understanding Pyrodinium bahamense harmful algal blooms in Manila Bay and Malampaya Sound, Philippines

Journal of Environmental Radioactivity ◽

10.1016/j.jenvrad.2004.03.025 ◽

2004 ◽

Vol 76 (1-2) ◽

pp. 177-194 ◽

Cited By ~ 15

Author(s):

E.Z Sombrito ◽

A.dM Bulos ◽

E.J Sta Maria ◽

M.C.V Honrado ◽

Rhodora V Azanza ◽

...

Keyword(s):

Harmful Algal Blooms ◽

Algal Blooms ◽

Sedimentation Rates ◽

Dinoflagellate Cyst ◽

Manila Bay ◽

Pyrodinium Bahamense

Download Full-text

Long- to short-term denudation rates in the southern Apennines: geomorphological markers and chronological constraints

Geologica Carpathica ◽

10.2478/v10096-011-0003-1 ◽

2011 ◽

Vol 62 (1) ◽

pp. 27-41 ◽

Cited By ~ 28

Author(s):

Dario Gioia ◽

Claudio Martino ◽

Marcello Schiattarella

Keyword(s):

Sediment Accumulation ◽

Radiometric Dating ◽

Sedimentation Rates ◽

Southern Apennines ◽

Short Term ◽

Small Catchment ◽

Fluvial Terraces ◽

Denudation Rates ◽

Land Surfaces

Long- to short-term denudation rates in the southern Apennines: geomorphological markers and chronological constraints Age constraints of geomorphological markers and consequent estimates of long- to short-term denudation rates from southern Italy are given here. Geomorphic analysis of the valley of the Tanagro River combined with apatite fission track data and radiometric dating provided useful information on the ages and evolution of some significant morphotectonic markers such as regional planated landscapes, erosional land surfaces and fluvial terraces. Reconstruction of paleotopography and estimation of the eroded volumes were perfomed starting from the plano-altimetric distribution of several orders of erosional land surfaces surveyed in the study area. Additional data about denudation rates related to the recent and/or active geomorphological system have been obtained by estimating the amount of suspended sediment yield at the outlet of some catchments using empirical relationships based on the hierarchical arrangement of the drainage network. Denudation rates obtained through these methods have been compared with the sedimentation rates calculated for two adjacent basins (the Pantano di San Gregorio and the Vallo di Diano), on the basis of published tephrochronological constraints. These rates have also been compared with those calculated for the historical sediment accumulation in a small catchment located to the north of the study area, with long-term exhumation data from thermochronometry, and with uplift rates from the study area. Long- and short-term denudation rates are included between 0.1 and 0.2 mm/yr, in good agreement with regional data and long-term sedimentation rates from the Vallo di Diano and the Pantano di San Gregorio Magno basins. On the other hand, higher values of exhumation rates from thermochronometry suggest the existence of past erosional processes faster than the recent and present-day exogenic dismantling. Finally, the comparison between uplift and denudation rates indicates that the fluvial erosion did not match the tectonic uplift during the Quaternary in this sector of the chain. The axial zone of the southern Apennines should therefore be regarded as a landscape in conditions of geomorphological disequilibrium.

Download Full-text

Long-Term Ecological Research in the Nakdong River: Application of Ecological Informatics to Harmful Algal Blooms

Ecological Informatics ◽

10.1007/978-3-319-59928-1_20 ◽

2017 ◽

pp. 435-453 ◽

Cited By ~ 1

Author(s):

Dong-Gyun Hong ◽

Kwang-Seuk Jeong ◽

Dong-Kyun Kim ◽

Gea-Jae Joo

Keyword(s):

Harmful Algal Blooms ◽

Algal Blooms ◽

Ecological Research ◽

Nakdong River ◽

Long Term Ecological Research ◽

The Nakdong River

Download Full-text

A trajectories' guide to the state space - learning missing terms in bifurcating ecological systems

10.5194/egusphere-egu21-16159 ◽

2021 ◽

Author(s):

Rahel Vortmeyer-Kley ◽

Pascal Nieters ◽

Gordon Pipa

Keyword(s):

Machine Learning ◽

Differential Equations ◽

Algal Blooms ◽

Ecological Systems ◽

Short Term ◽

Specific System ◽

Worst Case ◽

System Components ◽

Full Knowledge

Ecological systems typically can exhibit various states ranging from extinction to coexistence of different species in oscillatory states. The switch from one state to another is called bifurcation. All these behaviours of a specific system are hidden in a set of describing differential equations (DE) depending on different parametrisations. To model such a system as DE requires full knowledge of all possible interactions of the system components. In practise, modellers can end up with terms in the DE that do not fully describe the interactions or in the worst case with missing terms.The framework of universal differential equations (UDE) for scientific machine learning (SciML) [1] allows to reconstruct the incomplete or missing term from an idea of the DE and a short term timeseries of the system and make long term predictions of the system&#8217;s behaviour. However, the approach in [1] has difficulties to reconstruct the incomplete or missing term in systems with bifurcations. We developed a trajectory-based loss metric for UDE and SciML to tackle the problem and tested it successfully on a system mimicking algal blooms in the ocean.[1] Rackauckas, Christopher, et al. "Universal differential equations for scientific machine learning." arXiv preprint arXiv:2001.04385 (2020).

Download Full-text