scholarly journals Spring Accumulation Rates in North Atlantic Phytoplankton Communities Linked to Alterations in the Balance Between Division and Loss

2021 ◽  
Vol 12 ◽  
Author(s):  
Kristina D. A. Mojica ◽  
Michael J. Behrenfeld ◽  
Megan Clay ◽  
Corina P. D. Brussaard
Keyword(s):  
North Atlantic ◽  
Phytoplankton Biomass ◽  
Abiotic Factors ◽  
Mortality Rates ◽  
Rate Of Change ◽  
Specific Rate ◽  
Accumulation Rates ◽  
Light Levels ◽  
Phytoplankton Communities ◽  
Microzooplankton Grazing

For nearly a century, phytoplankton spring blooms have largely been explained in the context of abiotic factors regulating cellular division rates (e.g., mixed-layer light levels). However, the accumulation of new phytoplankton biomass represents a mismatch between phytoplankton division and mortality rates. The balance between division and loss, therefore, has important implications for marine food webs and biogeochemical cycles. A large fraction of phytoplankton mortality is due to the combination of microzooplankton grazing and viral lysis, however, broad scale simultaneous measurements of these mortality processes are scarce. We applied the modified dilution assay along a West-to-East diagonal transect in the North Atlantic during spring. Our results demonstrate positive accumulation rates with losses dominated by microzooplankton grazing. Considering the dynamic light environment phytoplankton experience in the mixed surface layer, particularly in the spring, we tested the potential for incubation light conditions to affect observed rates. Incubations acted as short-term ‘light’ perturbations experiments, in which deeply mixed communities are exposed to elevated light levels. These “light perturbations” increased phytoplankton division rates and resulted in proportional changes in phytoplankton biomass while having no significant effect on mortality rates. These results provide experimental evidence for the Disturbance-Recovery Hypothesis, supporting the tenet that biomass accumulation rates co-vary with the specific rate of change in division.

Differences between Nearshore and Offshore Phytoplankton Communities in Lake Ontario

1987 ◽  
Vol 44 (12) ◽  
pp. 2155-2163 ◽  
Author(s):  
I. M. Gray
Keyword(s):  
Chlorophyll A ◽  
Phytoplankton Biomass ◽  
Algal Biomass ◽  
Phytoplankton Community ◽  
Seasonal Pattern ◽  
Principal Component ◽  
Lake Ontario ◽  
Dominant Group ◽  
Phytoplankton Communities ◽  
Eutrophic Species

Differences between nearshore and offshore phytoplankton biomass and composition were evident in Lake Ontario in 1982. Phytoplankton biomass was characterized by multiple peaks which ranged over three orders of magnitude. Perhaps as a consequence of the three times higher current velocities at the northshore station, phytoplankton biomass ranged from 0.09 to 9.00 g∙m−3 compared with 0.10 to 2.40 g∙m−3 for the midlake station. Bacillariophyceae was the dominant group at the northshore station until September when Cyanophyta contributed most to the biomass (83%). Although Bacillariophyceae was the principal component of the spring phytoplankton community at the midlake station, phytoflagellates (49%) and Chlorophyceae (25%) were responsible for summer biomass, with the Chlorophyceae expanding to 80% in the fall. The seasonal pattern of epilimnetic chlorophyll a correlated with temperature. While chlorophyll a concentrations were similar to values from 1970 and 1972, algal biomass had declined and a number of eutrophic species (Melosira binderana, Stephanodiscus tenuis, S. hantzschii var. pusilla, and S. alpinus) previously found were absent in 1982.

Implementation of Self-Organizing Maps (SOM) to analyses of environmental parameters and phytoplankton biomass in a macrotidal estuary and artificial lake

2012 ◽  
Vol 93 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Roksana Jahan ◽  
Hyu Chang Choi ◽  
Young Seuk Park ◽  
Young Cheol Park ◽  
Ji Ho Seo ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Algal Blooms ◽  
Suspended Solids ◽  
Inorganic Nitrogen ◽  
Environmental Parameters ◽  
Ecological Data ◽  
Self Organizing Maps ◽  
Macrotidal Estuary ◽  
Phytoplankton Communities ◽  
Self Organizing

Self-Organizing Maps (SOM) have been used for patterning and visualizing ten environmental parameters and phytoplankton biomass in a mactrotidal (>10 m) Gyeonggi Bay and artificial Shihwa Lake during 1986–2004. SOM segregated study areas into four groups and ten subgroups. Two strikingly alternative states are frequently observed: the first is a diverse non-eutrophic state designated by three groups (SOM 1–3), and the second is a eutrophic state (SOM 4: Shihwa Lake and Upper Gyeonggi Bay; summer season) characterized by enhanced nutrients (3 mg l−1 dissolved inorganic nitrogen, 0.1 mg l−1 PO4) that act as a signal and response to that signal as algal blooms (24 µg chlorophyll-a l−1). Bloom potential in response to nitrification is affiliated with high temperature (r = 0.26), low salinity (r = −0.40) and suspended solids (r = –0.27). Moreover, strong stratification in the Shihwa Lake has accelerated harmful algal blooms and hypoxia. The non-eutrophic states (SOM 1–3) are characterized by macro-tidal estuaries exhibiting a tolerance to pollution with nitrogen-containing nutrients and retarding any tendency toward stratification. SOM 1 (winter) is more distinct from SOM 4 due to higher suspended solids (>50 mg l−1) caused by resuspension that induces light limitation and low chlorophyll-a (<5 µg l−1). In addition, eutrophication-induced shifts in phytoplankton communities are noticed during all the seasons in Gyeonggi Bay. Overall, SOM showed high performance for visualization and abstraction of ecological data and could serve as an efficient ecological map that can specify blooming regions and provide a comprehensive view on the eutrophication process in a macrotidal estuary.

Factors influencing the growth of Mougeotia in experimentally acidified mesocosms

2000 ◽  
Vol 57 (3) ◽  
pp. 538-547 ◽  
Author(s):  
Jennifer L Klug ◽  
Janet M Fischer
Keyword(s):  
Inorganic Carbon ◽  
Phytoplankton Community ◽  
Dissolved Inorganic Carbon ◽  
Abiotic Factors ◽  
Minor Role ◽  
Little Rock ◽  
Factors Associated ◽  
Phytoplankton Communities ◽  
Mesocosm Experiments ◽  
Potential Factors

Acidification causes profound changes in species composition in aquatic systems. We conducted mesocosm experiments in three northern Wisconsin lakes (Trout Lake, Little Rock - Reference, Little Rock - Treatment) to test how different phytoplankton communities respond to acidification. Major differences exist among these lakes in water chemistry and phytoplankton community composition. In each lake, three pH treatments (control, press (sustained pH 4.7), and pulse (alternating pH 4.7 and ambient pH)) were maintained for 6 weeks. We observed a striking increase in species in the genus Mougeotia in all systems. Mougeotia is a filamentous green alga often found in acidified lakes. The magnitude of the Mougeotia increase differed among lakes and treatments, and we used an autoregressive model to identify potential factors responsible for these differences. Our results suggest that biotic factors such as competition with other algae played a relatively minor role in regulating Mougeotia dynamics. Instead, pH and abiotic factors associated with changes in pH (e.g., dissolved inorganic carbon) were important predictors of Mougeotia dynamics.

scholarly journals Phytoplankton responses to an extreme drought season: A case study at two reservoirs from a semiarid region, Northeastern Brazil

2019 ◽  
Vol 78 (2) ◽  
Author(s):  
Carlos Y. B. Oliveira ◽  
Cicero D. L. Oliveira ◽  
Ayanne J. G. Almeida ◽  
Alfredo O. Gálvez ◽  
Danielli M. Dantas
Keyword(s):  
Electrical Conductivity ◽  
Phytoplankton Biomass ◽  
Inorganic Nitrogen ◽  
Abiotic Factors ◽  
Soluble Reactive Phosphorus ◽  
Extreme Drought ◽  
Northeastern Brazil ◽  
Semiarid Region ◽  
Drought Period ◽  
Reactive Phosphorus

The temporal phytoplankton biomass variation at two Neotropical reservoirs during an extreme drought season were analyzed. Here we sought to evaluate the main abiotic factors involved in dynamics of phytoplankton during this drought period. The main difference between the reservoirs was the intensive fish and shrimp farming in one of the reservoirs. For quantitative analysis, sampling with bottles were carried out at an average depth of 0.5m. Water temperature, pH and electrical conductivity parameters were measured in situ and water samples were collected for dissolved inorganic nitrogen and soluble reactive phosphorus analyses. Aquaculture was probably one among the causes for the reservoirs were so different in the physical and chemical variables, as shown by the principal components analysis. The results showed specific groups dominance in both reservoirs. In the Cachoeira II reservoir, an invasive dinoflagellate, Ceratium furcoides, was present in all analyzed months, while, in the Saco I reservoir, cyanobacteria group represented more than 50% of phytoplankton biomass, mainly Microcystis aeruginosa and Dolichospermum sp. In two reservoirs precipitation, soluble reactive phosphorus and electrical conductivity were positively related with phytoplankton. Phytoplankton biomass was considerably larger in the Cachoeira II reservoir, due to the greater size and biovolume of the dominant dinoflagellate. These findings suggest that species dominance in extreme drought events may be favored.

Parametric identification of the dynamics model in the system fertilizer-soil-plant

2020 ◽  
Author(s):  
В.А. Четырбоцкий ◽  
А.Н. Четырбоцкий
Keyword(s):  
Growth Rate ◽  
Mineral Nutrition ◽  
Mutual Influence ◽  
Parametric Identification ◽  
Rate Of Change ◽  
Specific Rate ◽  
Nutrient Contents ◽  
Phosphorus And Potassium ◽  
Model Equations ◽  
Dynamic Variables

Выполнена математическая формализация уравнений модели, для построения которой использовалась концепция системы ресурспотребитель. В рассматриваемом случае потребителем выступает биомасса растений, а ресурсомраспределенные в узкой прикорневой зоне растений основные элементы его минерального питания (азот, фосфор и калий). Динамические уравнения модели следуют основному положению химической кинетики, согласно которому результат взаимодействия динамических переменных в системах рассматриваемого профиля определяется их произведением. Выполнена оценка параметров и установлена адекватность модели выборочным распределениям. В качестве выборочных распределений используется массив экспериментальных данных роста яровой пшеницы (Красноуфимская-100) на торфяной низинной почве, предварительная почвенная обработка которой проведена с помощью азотных, фосфорных и калийных удобрений. Modern mathematical models for the simulation of dynamics in the fertilizer-soil-plant system, the components of which are agricultural plants, soil microorganisms and elements of their mineral nutrition, are considered. Based on the analysis of the adopted provisions, a model that takes into account the relationships and the specific nature of the joint changes in its components has been developed. The mathematical formalization of the model equations is carried out, for the construction of which the concept of the resourceconsumer system was used. In this case, the consumer is the biomass of plants, and the content of the main elements of its mineral nutrition distributed in the narrow basal zone of plants is a resource. The dynamic equations of the model follow the basic principle of chemical kinetics, according to which the result of the interaction between dynamic variables in the systems of the profile in question is determined by their product. The equations also contain the self-limitation factor, which sets the growth rate of the curve for the logistic equation and the specific rate of the model variables saturation effect. Thus, the specific rate of change in biomass is determined by its natural growth rate, the weighted sum of the nutrient contents in plants, and intraspecific competition. The rate of change in the content of these elements per unit of biomass is proportional to their current content in the rhizosphere and to the factor of the mutual influence of the elements on each other. The parameters are estimated and the adequacy of the model to sample distributions is established. An array of experimental data on the growth of spring wheat (Krasnoufimskaya-100) on peat lowland soil, the preliminary soil treatment of which was carried out using nitrogen, phosphorus, and potassium fertilizers, is used as sample distributions. The coefficients obtained as a result of parameter estimation and the calculated distributions of model dynamic variables with a sufficiently high degree of adequacy correspond to their experimental distributions and reflect the real situation of the system evolution.

scholarly journals Seasonal patterns in phytoplankton biomass across the northern and deep Gulf of Mexico: a numerical model study

2018 ◽  
Vol 15 (11) ◽  
pp. 3561-3576 ◽  
Author(s):  
Fabian A. Gomez ◽  
Sang-Ki Lee ◽  
Yanyun Liu ◽  
Frank J. Hernandez Jr. ◽  
Frank E. Muller-Karger ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Primary Production ◽  
Phytoplankton Biomass ◽  
Mississippi Delta ◽  
Three Dimensional ◽  
Rate Of Change ◽  
Integrated Analysis ◽  
Biogeochemical Model ◽  
Seasonal Patterns ◽  
Biogeochemical Models

Abstract. Biogeochemical models that simulate realistic lower-trophic-level dynamics, including the representation of main phytoplankton and zooplankton functional groups, are valuable tools for improving our understanding of natural and anthropogenic disturbances in marine ecosystems. Previous three-dimensional biogeochemical modeling studies in the northern and deep Gulf of Mexico (GoM) have used only one phytoplankton and one zooplankton type. To advance our modeling capability of the GoM ecosystem and to investigate the dominant spatial and seasonal patterns of phytoplankton biomass, we configured a 13-component biogeochemical model that explicitly represents nanophytoplankton, diatoms, micro-, and mesozooplankton. Our model outputs compare reasonably well with observed patterns in chlorophyll, primary production, and nutrients over the Louisiana–Texas shelf and deep GoM region. Our model suggests silica limitation of diatom growth in the deep GoM during winter and near the Mississippi delta during spring. Model nanophytoplankton growth is weakly nutrient limited in the Mississippi delta year-round and strongly nutrient limited in the deep GoM during summer. Our examination of primary production and net phytoplankton growth from the model indicates that the biomass losses, mainly due to zooplankton grazing, play an important role in modulating the simulated seasonal biomass patterns of nanophytoplankton and diatoms. Our analysis further shows that the dominant physical process influencing the local rate of change of model phytoplankton is horizontal advection in the northern shelf and vertical mixing in the deep GoM. This study highlights the need for an integrated analysis of biologically and physically driven biomass fluxes to better understand phytoplankton biomass phenologies in the GoM.

scholarly journals Long-term seasonal and spatial patterns in mortality and survival of Calanus finmarchicus across the Atlantic Zone Monitoring Programme region, Northwest Atlantic

2009 ◽  
Vol 66 (9) ◽  
pp. 1942-1958 ◽  
Author(s):  
Stéphane Plourde ◽  
Pierre Pepin ◽  
Erica J. H. Head
Keyword(s):  
Population Growth ◽  
Spatial Patterns ◽  
Phytoplankton Biomass ◽  
Mortality Rates ◽  
Monitoring Programme ◽  
Calanus Finmarchicus ◽  
Northwest Atlantic ◽  
Specific Mortality ◽  
Main Factor

Abstract Plourde, S., Pepin, P., and Head, E. J. H. 2009. Long-term seasonal and spatial patterns in mortality and survival of Calanus finmarchicus across the Atlantic Zone Monitoring Programme region, Northwest Atlantic. – ICES Journal of Marine Science, 66: 1942–1958. The vertical life table method was used to estimate stage-specific daily mortality rates and survival from 1999 to 2006 for Calanus finmarchicus sampled in the Canadian Atlantic Zone Monitoring Programme, which covers the Newfoundland–Labrador Shelf (NLS), Gulf of St Lawrence (GSL), and Scotian Shelf (SS). Stage-specific mortality rates and survival showed significant regional and seasonal differences, with the largest signal associated with variations in temperature. Density-dependent mortality, associated with the abundance of C6 females, was the main factor influencing mortality in the egg–C1 transition during the period of population growth in spring on the SS, and in summer in the GSL and on the NLS. In autumn, mortality in egg–C1 was positively related to temperature and negatively related to phytoplankton biomass, with particularly high mortality rates on the SS. The integration of our results into stage-specific recruitment rates from egg to C5 revealed that C. finmarchicus populations experience their greatest loss (mortality) during the egg–C1 transition. Loss during development to C1 was greater in the GSL than in the other regions during the period of population growth, resulting in lower recruitment success in the GSL. In autumn, C. finmarchicus showed low stage-specific daily recruitment rates on the SS at high temperatures, and low phytoplankton biomass compared with those in the GSL and on the NLS. Our findings reinforce the necessity of describing regional and seasonal patterns in mortality and survival to understand factors controlling the population dynamics of C. finmarchicus.

scholarly journals 14C Dated Chronology of the Thickest and Best Resolved Loess/Paleosol Record of the LGM from SE Hungary Based on Comparing Precision and Accuracy of Age-Depth Models

Radiocarbon ◽  
2020 ◽  
Vol 62 (2) ◽  
pp. 403-417
Author(s):  
Pál Sümegi ◽  
Sándor Gulyás ◽  
Dávid Molnár ◽  
Gábor Szilágyi ◽  
Balázs P Sümegi ◽  
...  
Keyword(s):  
Computer Program ◽  
Central Europe ◽  
North Atlantic ◽  
Small Scale ◽  
Sedimentation Rates ◽  
Accumulation Rates ◽  
Climatic Fluctuations ◽  
Precision And Accuracy ◽  
Calculated Average ◽  
Sedimentation Time

ABSTRACTThe Madaras profile found at the northernmost fringe of Bácska loess plateau is one of the thickest and best-developed last glacial loess sequences of Central Europe. The 10-m profile corresponds to a period between 29 and 12 b2k. To unravel feedback to small-scale centennial climatic fluctuations at our site, recorded in the Greenland ice and North Atlantic marine cores, construction of a reliable chronology is needed. Reliability is expressed in terms of best achievable chronological precision. Accuracy however is based on choosing the model best describing the sedimentological features of our profile. Five different age-depth models had constructed and compared relying on 15 14C dates using various statistical, probabilistic approaches to choose the model with the highest achievable precision. Accuracy was also evaluated using accumulation rates against stratigraphy. Models constructed using the computer program Bacon performed best in terms of achieving the best possible stratigraphic accuracy. Seven meters of the profile represents the period of the LGM. The average sedimentation time was 16.8 yr/cm with the highest confined to the period of the LGM. Calculated average sedimentation rates were 4 times higher than previously reported. The peak accumulation periods are dated to the nadir of the LGM.

scholarly journals Anthropogenic climate change drives shift and shuffle in North Atlantic phytoplankton communities

2016 ◽  
Vol 113 (11) ◽  
pp. 2964-2969 ◽  
Author(s):  
Andrew D. Barton ◽  
Andrew J. Irwin ◽  
Zoe V. Finkel ◽  
Charles A. Stock
Keyword(s):  
Climate Change ◽  
North Atlantic ◽  
Marine Species ◽  
Anthropogenic Climate Change ◽  
Marine Phytoplankton ◽  
Environmental Drivers ◽  
Individual Species ◽  
Ecological Niches ◽  
Phytoplankton Communities ◽  
Median Rate

Anthropogenic climate change has shifted the biogeography and phenology of many terrestrial and marine species. Marine phytoplankton communities appear sensitive to climate change, yet understanding of how individual species may respond to anthropogenic climate change remains limited. Here, using historical environmental and phytoplankton observations, we characterize the realized ecological niches for 87 North Atlantic diatom and dinoflagellate taxa and project changes in species biogeography between mean historical (1951–2000) and future (2051–2100) ocean conditions. We find that the central positions of the core range of 74% of taxa shift poleward at a median rate of 12.9 km per decade (km⋅dec−1), and 90% of taxa shift eastward at a median rate of 42.7 km⋅dec−1. The poleward shift is faster than previously reported for marine taxa, and the predominance of longitudinal shifts is driven by dynamic changes in multiple environmental drivers, rather than a strictly poleward, temperature-driven redistribution of ocean habitats. A century of climate change significantly shuffles community composition by a basin-wide median value of 16%, compared with seasonal variations of 46%. The North Atlantic phytoplankton community appears poised for marked shift and shuffle, which may have broad effects on food webs and biogeochemical cycles.

Microzooplankton grazing and the control of phytoplankton biomass in the Suwannee River estuary, USA

Hydrobiologia ◽  
2009 ◽  
Vol 632 (1) ◽  
pp. 127-137 ◽  
Author(s):  
Erin L. Quinlan ◽  
Christina H. Jett ◽  
Edward J. Phlips
Keyword(s):  
Phytoplankton Biomass ◽  
River Estuary ◽  
Suwannee River ◽  
Microzooplankton Grazing
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