scholarly journals Zooplankton Structure and Potential Food Web Interactions in the Plankton of a Subtropical Chain-of-Lakes

2002 ◽  
Vol 2 ◽  
pp. 926-942 ◽  
Author(s):  
Karl E. Havens
Keyword(s):  
Food Web ◽  
Phytoplankton Biomass ◽  
Size Structure ◽  
Fish Predation ◽  
Average Concentration ◽  
Zooplankton Biomass ◽  
Lake Okeechobee ◽  
Zooplankton Species ◽  
High Concentration ◽  
Chl A

This study evaluates the taxonomic and size structure of macro-zooplankton and its potential role in controlling phytoplankton in the Kissimmee Chain-of-Lakes, six shallow interconnected lakes in Florida, U.S. Macro-zooplankton species biomass and standard limnological attributes (temperature, pH, total phosphorus [TP], chlorophyll a [Chl a], and Secchi transparency) were quantified on a bimonthly basis from April 1997 to February 1999. Concentrations of TP ranged from below 50 to over 150 μg l-1. Peak concentrations of particulate P coincided with maximal Chl a, and in one instance a high concentration of soluble reactive P followed. The cladoceran zooplankton was dominated by small species, including Eubosmina tubicen, Ceriodaphnia rigaudi, and Daphnia ambigua. The exotic daphnid, D. lumholtzii, periodically was abundant. The copepods were strongly dominated by Diaptomus dorsalis, a species previously shown to be highly resistant to fish predation. These results, and findings of controlled experiments on a nearby lake with a nearly identical zooplankton species complement, suggest that fish predation may be a major factor structuring the macro-zooplankton assemblage. Zooplankton biomass, on the other hand, may be affected by resource availability. There was a significant positive relationship between average biomass of macro-zooplankton and the average concentration of TP among the six lakes. No such relationship existed between zooplankton biomass and Chl a, suggesting that the predominant food web in these systems may be based on bacteria-plankton, as has been documented in nearby Lake Okeechobee. All of the zooplankton taxa encountered in the Kissimmee Chain-of-Lakes (exceptMesocyclops edax) are known bacteria grazers in Florida lakes. Phytoplankton biomass, measured as Chl a, was strongly associated with TP, both within and across lakes. Phytoplankton biomass was not associated with the biomass of zooplankton. These results, when considered in the context of nutrient-addition, zooplankton-exclosure studies on Lake Okeechobee, support the hypothesis that phytoplankton biomass in subtropical lakes is regulated by —bottom-up,“ rather than —top-down“ forces.

scholarly journals Spatiotemporal Variability of Surface Phytoplankton Carbon and Carbon-to-Chlorophyll a Ratio in the South China Sea Based on Satellite Data

2020 ◽  
Vol 13 (1) ◽  
pp. 30
Author(s):  
Wenlong Xu ◽  
Guifen Wang ◽  
Long Jiang ◽  
Xuhua Cheng ◽  
Wen Zhou ◽  
...  
Keyword(s):  
South China Sea ◽  
Chlorophyll A ◽  
South China ◽  
Satellite Data ◽  
Phytoplankton Biomass ◽  
The South China Sea ◽  
Spatiotemporal Variability ◽  
The South ◽  
Chl A ◽  
China Sea

The spatiotemporal variability of phytoplankton biomass has been widely studied because of its importance in biogeochemical cycles. Chlorophyll a (Chl-a)—an essential pigment present in photoautotrophic organisms—is widely used as an indicator for oceanic phytoplankton biomass because it could be easily measured with calibrated optical sensors. However, the intracellular Chl-a content varies with light, nutrient levels, and temperature and could misrepresent phytoplankton biomass. In this study, we estimated the concentration of phytoplankton carbon—a more suitable indicator for phytoplankton biomass—using a regionally adjusted bio-optical algorithm with satellite data in the South China Sea (SCS). Phytoplankton carbon and the carbon-to-Chl-a ratio (θ) exhibited considerable variability spatially and seasonally. Generally, phytoplankton carbon in the northern SCS was higher than that in the western and central parts. The regional monthly mean phytoplankton carbon in the northern SCS showed a prominent peak during December and January. A similar pattern was shown in the central part of SCS, but its peak was weaker. Besides the winter peak, the western part of SCS had a secondary maximum of phytoplankton carbon during summer. θ exhibited significant seasonal variability in the northern SCS, but a relatively weak seasonal change in the western and central parts. θ had a peak in September and a trough in January in the northern and central parts of SCS, whereas in the western SCS the minimum and maximum θ was found in August and during October–April of the following year, respectively. Overall, θ ranged from 26.06 to 123.99 in the SCS, which implies that the carbon content could vary up to four times given a specific Chl-a value. The variations in θ were found to be related to changing phytoplankton community composition, as well as dynamic phytoplankton physiological activities in response to environmental influences; which also exhibit much spatial differences in the SCS. Our results imply that the spatiotemporal variability of θ should be considered, rather than simply used a single value when converting Chl-a to phytoplankton carbon biomass in the SCS, especially, when verifying the simulation results of biogeochemical models.

Size structure of phytoplankton biomass and photosynthesis in subtropical Hawaiian waters

1983 ◽  
Vol 76 (2) ◽  
pp. 203-211 ◽  
Author(s):  
M. Takahashi ◽  
P. K. Bienfang
Keyword(s):  
Phytoplankton Biomass ◽  
Size Structure

scholarly journals Factor influencing the spatio-tempoaral distribution of zooplankton biomass in the Merbok estuary, Malaysia

2016 ◽  
Vol 44 (1) ◽  
pp. 147-152
Author(s):  
Kaniz Fatema ◽  
Wan Maznah Wan Omar ◽  
Mansor Mat Isa ◽  
Md Omar Ahmad
Keyword(s):  
Correlation Analysis ◽  
Rank Correlation ◽  
Temporal Distribution ◽  
Mesh Size ◽  
Zooplankton Biomass ◽  
Spatial And Temporal Distribution ◽  
Chl A ◽  
River Stretch ◽  
Merbok Estuary

Spatial and temporal distribution of zooplankton biomass in the Merbok estuary were studied. Zooplankton samples were collected monthly from January to December 2011 at six sampling stations along the river stretch by using 0.13 m diameter plankton net (150 ?m mesh size) in horizontal towing. Average zooplankton biomass ranged from 0.1143 to 1.8217 g dry wt.m-3. The maximum and minimum zooplankton biomass recorded in February and October 2011, respectively. The highest zooplankton biomass was found at Station 6 (downstream) and the lowest in Station 1 (upstream). Zooplankton biomass varied from upstream to downstream. Kruskal-Wallis H test showed that distribution of zooplankton biomass among the sampling months was significantly different (p < 0.05). Spearman’s rank correlation analysis revealed significant correlation among zooplankton biomass, chl a concentration and nutrients (p < 0·01).Bangladesh J. Zool. 44(1): 147-152, 2016

scholarly journals Effects of nitrogen enrichment on zooplankton biomass and N:P recycling ratios across a DOC gradient in northern-latitude lakes

Hydrobiologia ◽  
2021 ◽  
Author(s):  
A.-K. Bergström ◽  
A. Deininger ◽  
A. Jonsson ◽  
J. Karlsson ◽  
T. Vrede
Keyword(s):  
Community Composition ◽  
Resource Use ◽  
Phytoplankton Biomass ◽  
Phytoplankton Community ◽  
N Fertilization ◽  
Zooplankton Biomass ◽  
Nitrogen Enrichment ◽  
C:N:P Stoichiometry ◽  
Food Quantity ◽  
N Enrichment

AbstractWe used data from whole-lake studies to assess how changes in food quantity (phytoplankton biomass) and quality (phytoplankton community composition, seston C:P and N:P) with N fertilization affect zooplankton biomass, community composition and C:N:P stoichiometry, and their N:P recycling ratio along a gradient in lake DOC concentrations. We found that despite major differences in phytoplankton biomass with DOC (unimodal distributions, especially with N fertilization), no major differences in zooplankton biomass were detectable. Instead, phytoplankton to zooplankton biomass ratios were high, especially at intermediate DOC and after N fertilization, implying low trophic transfer efficiencies. An explanation for the observed low phytoplankton resource use, and biomass responses in zooplankton, was dominance of colony forming chlorophytes of reduced edibility at intermediate lake DOC, combined with reduced phytoplankton mineral quality (enhanced seston N:P) with N fertilization. N fertilization, however, increased zooplankton N:P recycling ratios, with largest impact at low DOC where phytoplankton benefitted from light sufficiently to cause enhanced seston N:P. Our results suggest that although N enrichment and increased phytoplankton biomass do not necessarily increase zooplankton biomass, bottom-up effects may still impact zooplankton and their N:P recycling ratio through promotion of phytoplankton species of low edibility and altered mineral quality.

scholarly journals GLOBAL PRODUCTION CONCENTRATION OF MEDIUM DENSITY FIBERBOARD (MDF) (1995 - 2016)

2018 ◽  
Vol 42 (5) ◽  
Author(s):  
Thaisa de Sousa Selvatti ◽  
Luis Antônio Coimbra Borges ◽  
Helena Cristina Carvalho Soares ◽  
Álvaro Nogueira de Souza ◽  
Luiz Moreira Coelho Junior
Keyword(s):  
Gini Index ◽  
Concentration Ratio ◽  
Concentration Index ◽  
Medium Density Fiberboard ◽  
Average Concentration ◽  
Medium Density ◽  
High Concentration ◽  
The World ◽  
Concentration Degree ◽  
Production Concentration

ABSTRACT This papaer analyzed the global MDF production and its concentration degree between 1995 and 2016. In order to measure and analyze this concentration, we used the Concentration Ratio [CR(k)], the Herfindahl-Hirschman Index (HHI), Theil Entropy Index (E), Hall and Tideman Index (HTI), the Comprehensive Concentration Index (CCI), and the Gini Index (G). Global MDF production grew 12.81% p.a. from 1995 to 2016, reaching 99 million m3 at the end of the time series. China took over the hegemony in 2001 and arrived in 2016 with about 60% of the world’s MDF supply. The CR(k) of the global MDF production inferred a high concentration, mainly in the CR(4) from 2009. The CR(8) remained with a moderately high average concentration. During this period more than 90% of the offer was retained in the CR(20). The HHI, E and HTI indices corroborate that there is high concentration in global MDF production, as well as the CCI in the studied period. The inequality indicated by G also presented increasing behavior and was classified as strong and very strong. The concentration indicators were efficient in evaluating the concentration degree of the world MDF supply.

scholarly journals Trophic niche breadth of pond zooplankton species using stable isotope analysis and the relationship with the abiotic and biotic factors

2019 ◽  
Vol 6 (1) ◽  
pp. 180917 ◽  
Author(s):  
Hideyuki Doi ◽  
Kwang-Hyeon Chang ◽  
Shin-ichi Nakano
Keyword(s):  
Stable Isotope ◽  
Niche Breadth ◽  
Resource Competition ◽  
Feeding Habits ◽  
Zooplankton Biomass ◽  
Trophic Niche ◽  
Zooplankton Species ◽  
Carbon And Nitrogen ◽  
Ecosystem Size ◽  
The Relationship

Zooplankton species have different feeding habits, but the diversity of their food resources and the factors governing them are still largely unknown. We here estimated the differences in the trophic niche breadths of dominant zooplankton species in ponds, using stable isotopes. To understand the differences in trophic niches of different zooplankton species, we measured the carbon and nitrogen stable isotope ratios and calculated the nearest-neighbour distance (NND), and standard deviation of NND (SDNND) of the bi-plot space of stable carbon and nitrogen isotopes in pond zooplankton. We tested the relationship between the NND/SDNND and environmental factors, as well as the zooplankton biomass, using generalized linear models (GLMs). For cladocerans, including Bosmina, Ceriodaphnia and Daphnia, the NNDs were significantly correlated with the biomass, pond morphology (volume and depth), total phosphorous (TP) and fish presence. For copepod species, including Eodiaptomus and cyclopoids, NNDs were significantly correlated with pond morphology, TP and fish presence, but not with biomass. In GLMs of SDNND, significant correlated factors were less than those for NND, and for some species, pond morphology and TP were significantly correlated with SDNND. Here, we found that the NND and SDNND of zooplankton species were related to various factors, including their biomass, predator presence, pond size and water quality. For cladocerans, biomass may be supported by trophic niche breadth, probably because of the consequences of resource competition. Also, predation and ecosystem size may influence trophic niche breadth due to changes in zooplankton behaviours.

Global patterns in phytoplankton biomass and community size structure in relation to macronutrients in the open ocean

2018 ◽  
Vol 63 (3) ◽  
pp. 1298-1312 ◽  
Author(s):  
Erik Askov Mousing ◽  
Katherine Richardson ◽  
Marianne Ellegaard
Keyword(s):  
Phytoplankton Biomass ◽  
Size Structure ◽  
Open Ocean ◽  
Community Size ◽  
Global Patterns

scholarly journals Responses of food web to hypolimnetic aeration in Lake Vesijärvi

Hydrobiologia ◽  
2020 ◽  
Vol 847 (21) ◽  
pp. 4503-4523 ◽  
Author(s):  
Jukka Ruuhijärvi ◽  
Tommi Malinen ◽  
Kirsi Kuoppamäki ◽  
Pasi Ala-Opas ◽  
Mika Vinni
Keyword(s):  
Body Size ◽  
Food Web ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Perca Fluviatilis ◽  
Fish Predation ◽  
Filamentous Cyanobacteria ◽  
Low Oxygen ◽  
High Quality ◽  
Oxygen Conditions

AbstractWe studied the responses of a food web, especially fish and zooplankton, to summertime aeration, pumping of oxygen-rich epilimnetic water to the hypolimnion in Lake Vesijärvi, southern Finland. The aim of hypolimnetic aeration was to reduce internal loading of phosphorus from sediment. The population of smelt (Osmerus eperlanus L.), the main planktivore of the pelagial area, collapsed during the two 1st years of aeration due to increased temperature and low oxygen concentrations in the hypolimnion. The population recovered after the 4th year of hypolimnetic aeration, when oxygen conditions were improved. Despite elevated hypolimnetic temperature, smelt reached exceptionally high abundance, which led to a significant reduction in cladoceran body size. The density of perch (Perca fluviatilis L.) increased at first, but then decreased when the proportion of smelt and cyprinids increased. Biomasses of Daphnia decreased probably as a result of the disappearance of dark, low-oxygen deep-water refuge against fish predation and low availability of nutritionally high-quality algae. Occasionally filamentous cyanobacteria, such as turbulence tolerant Planktothrix agardhii (Gomont), were abundant, suggesting deteriorated food resources for zooplankton. The responses of food web were controversial with respect to the aim of the management, which was to prevent the occurrence of harmful algal blooms.

scholarly journals Tracing the Origin of Groundwater Nitrate in an Area Affected by Acid Rain Using Dual Isotopic Composition of Nitrate

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Tianming Huang ◽  
Zhenbin Li ◽  
Baoqiang Ma ◽  
Yin Long
Keyword(s):  
Isotopic Composition ◽  
Acid Rain ◽  
Nitrogen Cycle ◽  
Soil Nitrogen ◽  
Average Concentration ◽  
Mountainous Area ◽  
Rock Weathering ◽  
High Concentration ◽  
Groundwater System ◽  
Denitrification Process

Acid rain with a relatively high concentration of ammonium and nitrate can accelerate rock weathering. However, its impact on groundwater nitrate is uncertain. This study evaluated the dual isotopic composition of nitrate (δ15N-NO3- and δ18O-NO3-) from precipitation to groundwater in a rural mountainous area affected by acid rain. The average concentration for NH4+ is 1.25 mg/L and NO3- is 2.59 mg/L of acid rain. Groundwater NO3- concentrations ranged from <0.05 to 11.8 mg/L (baseline), and NH4+ concentrations ranged from 0.06 to 0.28 mg/L. The results show that groundwater δ18O-NO3- values (-4.7‰ to +4.2‰) were lower than the values of rainfall δ18O-NO3- (+24.9‰ to +67.3‰), suggesting that rainfall NO3- contributes little to groundwater NO3-. Groundwater δ15N-NO3- values (+0.1‰ to +7.5‰) were higher than the values of δ15N-NO3- derived from the nitrification of rainfall NH4+ (less than -4.7‰ in the study area), suggesting that nitrification of rainfall NH4+ also contributes little to groundwater NO3-. This implies that rainfall NO3- and NH4+ have been utilized. The dual isotopic composition of nitrate shows that baseline groundwater NO3- is derived mainly from nitrification of soil nitrogen. The denitrification process is limited in the groundwater system. This study shows that the rainfall NO3- and NH4+ contribute little to groundwater NO3-, improving the understanding of the nitrogen cycle in areas with a high concentration of NH4+ and NO3- in rainfall.

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