Grazing by a river zooplankton community: Importance of microzooplankton

1996 ◽  
Vol 47 (8) ◽  
pp. 1025 ◽  
Author(s):  
T Kobayashi ◽  
P Gibbs ◽  
PI Dixon ◽  
RJ Shiel
Keyword(s):  
Surface Temperature ◽  
Phytoplankton Community ◽  
Size Fraction ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Regulated River ◽  
Grazing Impact ◽  
Total Biomass ◽  
Community Grazing ◽  
The Impact

Grazing rates by a zooplankton community were measured in situ by a radiotracer cell method at depths of 1 m and 4 m at the upper tidal freshwater portion of a regulated river over a year. The objectives were to evaluate the likely grazing impact on the river phytoplankton community and to produce predictive models by regressing the measured grazing rates against zooplankton biomass, temperature and food concentrations (represented by chlorophyll a). Grazing attained rates (overall average 0.2 day-1, range 0.01-0.59 day-1, expressed as instantaneous mortality rates of algal cells) comparable to those reported for lentic zooplankton communities. The measured community grazing rates were predictable largely as a function of total biomass or rotifer biomass and surface temperature for 1 m depth, and as a function of total biomass or juvenile copepod biomass and surface temperature for 4 m depth, with all-positive regression coefficients in the models. Owing to the predominance of microzooplankton in the river, the impact of zooplankton community grazing appears likely to be linked to a small-size fraction of the phytoplankton community all year. Management strategies for river water quality may need to take account of possible functional demarcation of grazing by river zooplankton.

scholarly journals Zooplankton Community Responses to Oxygen Stress

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 706 ◽  
Author(s):  
Maciej Karpowicz ◽  
Jolanta Ejsmont-Karabin ◽  
Joanna Kozłowska ◽  
Irina Feniova ◽  
Andrew R. Dzialowski
Keyword(s):  
Zooplankton Community ◽  
Oxygen Depletion ◽  
Zooplankton Biomass ◽  
Oxygen Stress ◽  
Carbon Transfer ◽  
Oxygen Conditions ◽  
Anoxic Layer ◽  
Zooplankton Communities ◽  
The Impact

Recent changes in climate and eutrophication have caused increases in oxygen depletion in both freshwater and marine ecosystems. However, the impact of oxygen stress on zooplankton, which is the major trophic link between primary producers and fish, remains largely unknown in lakes. Therefore, we studied 41 lakes with different trophic and oxygen conditions to assess the role of oxygen stress on zooplankton communities and carbon transfer between phytoplankton and zooplankton. Samples were collected from each lake at the peak of summer stratification from three depth layers (the epilimnion, metalimnion, and hypolimnion). Our results revealed that freshwater zooplankton were relatively tolerant to anoxic conditions and the greatest changes in community structure were found in lakes with the highest oxygen deficits. This caused a switch in dominance from large to small species and reduced the zooplankton biomass in lower, anoxic layers of water, but not in the upper layers of water where the oxygen deficits began. This upper anoxic layer could thus be a very important refuge for zooplankton to avoid predation during the day. However, the reduction of zooplankton in the lower water layers was the main factor that reduced the effectiveness of carbon transfer between the phytoplankton and zooplankton.

Effect of an invasive filter-feeder on the zooplankton assemblage in a coastal lagoon

2015 ◽  
Vol 96 (6) ◽  
pp. 1201-1210 ◽  
Author(s):  
Martin Bruschetti ◽  
Tomas Luppi ◽  
Oscar Iribarne
Keyword(s):  
Phytoplankton Biomass ◽  
Food Resource ◽  
Zooplankton Community ◽  
Grazing Intensity ◽  
Trophic Levels ◽  
Grazing Impact ◽  
Filter Feeder ◽  
Cascading Effects ◽  
Mesocosm Experiments ◽  
The Impact

Depletion of phytoplankton biomass by the introduced reef-forming polychaete Ficopomatus enigmaticus has previously been observed in the Mar Chiquita lagoon (37°40′S 57°23′W; Argentina), but the effect of polychaetes on the higher trophic levels is still unknown. To evaluate the effect of this polychaete on the zooplankton assemblage, replicated mesocosm experiments (N = 10) were performed during spring, summer and winter. Mesocosms with reefs and without reefs were installed and grazing intensity and the effect on the zooplankton assemblage by the polychaetes were assessed. Our results show that the reefs of F. enigmaticus generate minor changes in overall composition of zooplankton assemblage. Although the structure of the zooplankton assemblage was different between seasons, the impact of the reefs was not significant in any of them. There was no relationship between the decline of food resource by grazing and changes in the structure of the zooplankton assemblage. Thus, contrary to our hypothesis, the grazing impact of the invasive polychaete on the biomass of primary producers did not generate cascading effects to higher trophic levels. However, changes in some components of the zooplankton assemblage (e.g. cladocerans) clearly show that the reefs of F. enigmaticus have the potential to affect the structure of the zooplankton community. The lack of data of community composition and abundance of zooplankton before the invasion limits the understanding of how this polychaete might have affected the structure and abundance of the zooplankton of this lagoon. Nevertheless this work suggests that these changes may not be so significant.

Phytoplankton community size structure, primary production and copepod production in a subtropical coastal inlet in Hong Kong

2013 ◽  
Vol 93 (8) ◽  
pp. 2155-2166 ◽  
Author(s):  
Alle A.Y. Lie ◽  
Lik Chi Wong ◽  
C. Kim Wong
Keyword(s):  
Hong Kong ◽  
Primary Production ◽  
Phytoplankton Community ◽  
Size Structure ◽  
Net Primary Production ◽  
Size Fraction ◽  
Zooplankton Community ◽  
Community Size ◽  
Phytoplankton Primary Production ◽  
Tolo Harbour

Phytoplankton primary production and copepod production, and the size composition of the phytoplankton community in Tolo Harbour, a semi-enclosed bay in north-eastern Hong Kong, were studied from February 2008 to March 2009. Chlorophyll-a (Chl a) concentrations decreased from an average of 9.07 µg l−1 in the inner part of the bay to 3.07 µg l−1 at the mouth of the bay. In terms of contribution to total Chl a biomass, the >20 µm size fraction dominated the phytoplankton community. The zooplankton community in Tolo Harbour was dominated by small copepods, with cephalothorax length ranging from ~0.3 to 0.4 mm, and the density of copepods decreased from ~15,000 ind.m−3 in the inner part of the bay to ~9,700 ind.m−3 at the mouth of the bay. Depth-integrated net primary production in Tolo Harbour was high, ranging from 0.34 to 10.40 g C m−2 day−1, with an overall mean of 2.64 g C m−2 day−1. In contrast, copepod production was low, ranging from 0.19 to 16.64 mg C m−3 day−1, with an overall mean of 2.73 mg C m−3 day−1. The low transfer efficiency of 1.4% between phytoplankton primary production and copepod secondary production suggests that the large phytoplankton was inefficiently grazed by the small copepods in Tolo Harbour.

scholarly journals Distribution and feeding of dominant zooplankton species under autumn coccolithophorid development in the eastern part of the Barents sea

2019 ◽  
Vol 59 (5) ◽  
pp. 734-745
Author(s):  
V. M. Sergeeva ◽  
A. V. Drits ◽  
M. V. Flint
Keyword(s):  
Spatial Distribution ◽  
Barents Sea ◽  
Feeding Activity ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Calanus Finmarchicus ◽  
Grazing Impact ◽  
The Barents Sea ◽  
Diel Vertical Migrations ◽  
Upper Mixed Layer

Studies of zooplankton spatial distribution and feeding were conducted in the eastern part of the Barents Sea in early October 2014. The study period was characterized by positive anomalies of the water temperature in the upper mixed layer and by the dominance of coccolithophorids in phytoplankton. The scale of spatial variability of zooplankton biomass (6.143.3 mg DW m-3) over the 30,000 km2 investigated area was comparable to the range of interannual variation of zooplankton biomass in the Barents Sea. Calanus finmarchicus and Metridia longa dominated in the zooplankton community. The spatial distribution of C. finmarchicus was correlated with the depth: at the stations, where the depth exceeded 250 m, the biomass was threefold higher than that at the shallower stations. Both species performed diel vertical migrations ascending to the upper 50 m layer during night and actively consuming there coccolithophorids and tintinnids Acanthostomella norvegica. Taking into account the contribution of tintinnids, the amount of assimilated organic carbon in C. finmarchicus CV, CIV and M. longa CV, CIV was 2.6, 8.3 and 3.5, 4.9% of body carbon content, respectively, and compensated therefore the metabolic costs. Grazing impact on the autotrophic phytoplankton by the populations of C. finmarchicus and M. longa did not exceed 5% of its biomass and was preconditioned by the abundance and the feeding activity of migrating copepods.

scholarly journals Can microcystins affect zooplankton structure community in tropical eutrophic reservoirs?

2016 ◽  
Vol 76 (2) ◽  
pp. 450-460 ◽  
Author(s):  
T. A. S. V. Paes ◽  
I. A. S. Costa ◽  
A. P. C. Silva ◽  
E. M. Eskinazi-Sant’Anna
Keyword(s):  
Zooplankton Community ◽  
Population Level ◽  
Temporal Variations ◽  
Zooplankton Biomass ◽  
Total Biomass ◽  
Control Mechanisms ◽  
Calanoid Copepods ◽  
Negative Effects ◽  
Eutrophic Reservoirs ◽  
Allelopathic Compounds

Abstract The aim of our study was to assess whether cyanotoxins (microcystins) can affect the composition of the zooplankton community, leading to domination of microzooplankton forms (protozoans and rotifers). Temporal variations in concentrations of microcystins and zooplankton biomass were analyzed in three eutrophic reservoirs in the semi-arid northeast region of Brazil. The concentration of microcystins in water proved to be correlated with the cyanobacterial biovolume, indicating the contributions from colonial forms such as Microcystis in the production of cyanotoxins. At the community level, the total biomass of zooplankton was not correlated with the concentration of microcystin (r2 = 0.00; P > 0.001), but in a population-level analysis, the biomass of rotifers and cladocerans showed a weak positive correlation. Cyclopoid copepods, which are considered to be relatively inefficient in ingesting cyanobacteria, were negatively correlated (r2 = – 0.01; P > 0.01) with the concentration of cyanotoxins. Surprisingly, the biomass of calanoid copepods was positively correlated with the microcystin concentration (r2 = 0.44; P > 0.001). The results indicate that allelopathic control mechanisms (negative effects of microcystin on zooplankton biomass) do not seem to substantially affect the composition of mesozooplankton, which showed a constant and high biomass compared to the microzooplankton (rotifers). These results may be important to better understand the trophic interactions between zooplankton and cyanobacteria and the potential effects of allelopathic compounds on zooplankton.

scholarly journals Zooplankton community grazing impact on a toxic bloom of Alexandrium fundyense in the Nauset Marsh System, Cape Cod, Massachusetts, USA

Harmful Algae ◽  
2015 ◽  
Vol 47 ◽  
pp. 42-55 ◽  
Author(s):  
Christian M. Petitpas ◽  
Jefferson T. Turner ◽  
Bruce A. Keafer ◽  
Dennis J. McGillicuddy ◽  
Donald M. Anderson
Keyword(s):  
Zooplankton Community ◽  
Cape Cod ◽  
Grazing Impact ◽  
Alexandrium Fundyense ◽  
Community Grazing ◽  
Toxic Bloom

Impact of LULC Changes on LST in Rajshahi District of Bangladesh: A Remote Sensing Approach

2020 ◽  
Vol 3 (1) ◽  
pp. 11-23 ◽  
Author(s):  
Abdulla Al Kafy ◽  
Abdullah Al-Faisal ◽  
Mohammad Mahmudul Hasan ◽  
Md. Soumik Sikdar ◽  
Mohammad Hasib Hasan Khan ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Surface Temperature ◽  
Land Surface ◽  
Agricultural Land ◽  
Global Climate ◽  
Urban Expansion ◽  
Water Bodies ◽  
Landsat 8 ◽  
Lulc Changes ◽  
The Impact

Urbanization has been contributing more in global climate warming, with more than 50% of the population living in cities. Rapid population growth and change in land use / land cover (LULC) are closely linked. The transformation of LULC due to rapid urban expansion significantly affects the functions of biodiversity and ecosystems, as well as local and regional climates. Improper planning and uncontrolled management of LULC changes profoundly contribute to the rise of urban land surface temperature (LST). This study evaluates the impact of LULC changes on LST for 1997, 2007 and 2017 in the Rajshahi district (Bangladesh) using multi-temporal and multi-spectral Landsat 8 OLI and Landsat 5 TM satellite data sets. The analysis of LULC changes exposed a remarkable increase in the built-up areas and a significant decrease in the vegetation and agricultural land. The built-up area was increased almost double in last 20 years in the study area. The distribution of changes in LST shows that built-up areas recorded the highest temperature followed by bare land, vegetation and agricultural land and water bodies. The LULC-LST profiles also revealed the highest temperature in built-up areas and the lowest temperature in water bodies. In the last 20 years, LST was increased about 13ºC. The study demonstrates decrease in vegetation cover and increase in non-evaporating surfaces with significantly increases the surface temperature in the study area. Remote-sensing techniques were found one of the suitable techniques for rapid analysis of urban expansions and to identify the impact of urbanization on LST.

scholarly journals Interannual Variability and Trends in Sea Surface Temperature, Lower and Middle Atmosphere Temperature at Different Latitudes for 1980–2019

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 454
Author(s):  
Andrew R. Jakovlev ◽  
Sergei P. Smyshlyaev ◽  
Vener Y. Galin
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Lower Stratosphere ◽  
Middle Atmosphere ◽  
Southern Oscillation ◽  
Lower Troposphere ◽  
Reanalysis Data ◽  
Sea Surface ◽  
The Arctic ◽  
The Impact

The influence of sea-surface temperature (SST) on the lower troposphere and lower stratosphere temperature in the tropical, middle, and polar latitudes is studied for 1980–2019 based on the MERRA2, ERA5, and Met Office reanalysis data, and numerical modeling with a chemistry-climate model (CCM) of the lower and middle atmosphere. The variability of SST is analyzed according to Met Office and ERA5 data, while the variability of atmospheric temperature is investigated according to MERRA2 and ERA5 data. Analysis of sea surface temperature trends based on reanalysis data revealed that a significant positive SST trend of about 0.1 degrees per decade is observed over the globe. In the middle latitudes of the Northern Hemisphere, the trend (about 0.2 degrees per decade) is 2 times higher than the global average, and 5 times higher than in the Southern Hemisphere (about 0.04 degrees per decade). At polar latitudes, opposite SST trends are observed in the Arctic (positive) and Antarctic (negative). The impact of the El Niño Southern Oscillation phenomenon on the temperature of the lower and middle atmosphere in the middle and polar latitudes of the Northern and Southern Hemispheres is discussed. To assess the relative influence of SST, CO2, and other greenhouse gases’ variability on the temperature of the lower troposphere and lower stratosphere, numerical calculations with a CCM were performed for several scenarios of accounting for the SST and carbon dioxide variability. The results of numerical experiments with a CCM demonstrated that the influence of SST prevails in the troposphere, while for the stratosphere, an increase in the CO2 content plays the most important role.

scholarly journals Impact of Incorporating NIR Reflective Pigments in Finishing Coatings of ETICS

2021 ◽  
Vol 6 (6) ◽  
pp. 79
Author(s):  
Nuno M. M. Ramos ◽  
Joana Maia ◽  
Andrea R. Souza ◽  
Ricardo M. S. F. Almeida ◽  
Luís Silva
Keyword(s):  
Surface Layer ◽  
Surface Temperature ◽  
Near Infrared ◽  
Building Performance ◽  
Colour Difference ◽  
Colour Perception ◽  
Composite Systems ◽  
Solar Reflectance ◽  
Building Cooling ◽  
The Impact

Near-infrared (NIR) reflective materials are being developed for mitigating building cooling needs. Their use contributes to broadening the range of colours, responding to the urban aesthetic demand without compromising the building performance. Despite the increase in NIR reflective pigments investigation, there is still a knowledge gap in their applicability, impact, and durability in multilayer finishing coatings of External Thermal Insulation Composite Systems (ETICS). Hence, the main goal of this work consists of evaluating the impact of incorporating NIR reflective pigments (NRP) in the solar reflectance of the surface layer of ETICS, without affecting the colour perception, as well as their influence on the colour durability and surface temperature. As such, colour, solar reflectance, and surface temperature were monitored for 2 years in dark-coloured specimens of ETICS, with and without NRP and a primer layer. It was confirmed that the main contribution of NRP is the increase of solar reflectance and, consequently, the decrease in surface temperature, especially for high exterior temperatures (around 30 ºC). Moreover, these pigments highly increase the NIR reflectance without affecting the visible colour. In addition, they contribute to maintaining the colour characteristics. The application of primer increased the surface temperature, especially for higher exterior temperatures. However, it contributes to a lower colour difference and solar reflectance variation, which is an important achievement for durability purposes.

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