Zooplankton dynamics during autumn circulation in a small, wind-sheltered, Mediterranean lake

2006 ◽  
Vol 57 (4) ◽  
pp. 441 ◽  
Author(s):  
M. Alvarez-Cobelas ◽  
A. Baltanás ◽  
J. L. Velasco ◽  
C. Rojo
Keyword(s):  
Water Temperature ◽  
Current Model ◽  
Fish Predation ◽  
Controlling Factors ◽  
Heterotrophic Nanoflagellates ◽  
Delayed Effects ◽  
Zooplankton Dynamics ◽  
Mediterranean Lake ◽  
Fish Abundances ◽  
Ceriodaphnia Reticulata

Few studies have been undertaken on zooplankton dynamics during the transition from late stratification to early mixing in lakes. The Plankton Ecology Group (PEG) model of plankton seasonality only considers water temperature, edible phytoplankton and fish predation as zooplankton-controlling factors during that period. The water-column edible algal and bacterial fractions, heterotrophic nanoflagellates, ciliates, rotifers, cladocerans and copepods were studied during 93 consecutive days of mixing-transition in a wind-sheltered, Mediterranean lake without planktivorous fish. Abundances of all zooplankton populations except ciliates, Daphnia longispina and copepodites, were related to water temperature. In addition to PEG controlling factors, time series analysis indicated competition between ciliates and Ceriodaphnia reticulata and Polyarthra dolichoptera and D. longispina, predation of Arctodiaptomus salinus on ciliates, herbivory of adult copepods on the 5–20 μm phytoplanktonic size and delayed effects shorter than one week. The remaining zooplankton populations did not show any edible size preference. Ceriodaphnia reticulata showed evidence of herbivory on bacteria and picoplankton and competition with Hexarthra fennica in shorter periods. Phyto- and zooplankton production were decoupled. These results, and others from warmer periods and latitudes, suggest that the current model of lake plankton seasonality must be reviewed.

scholarly journals Upper thermal threshold of Lepidurus arcticus (Branchiopoda, Notostraca) in lakes on the southern outreach of its distribution range

2021 ◽  
Vol 41 ◽  
pp. 50-88
Author(s):  
Tore Qvenild ◽  
Eirik Fjeld ◽  
Arne Fjellheim ◽  
Johan Hammar ◽  
Trygve Hesthagen ◽  
...  
Keyword(s):  
Water Temperature ◽  
Fish Predation ◽  
High Arctic ◽  
Water Bodies ◽  
The Arctic ◽  
Thermal Threshold ◽  
Tadpole Shrimp ◽  
Area North ◽  
Regulated Lakes ◽  
Southern Island

The Arctic tadpole shrimp Lepidurus arcticus has a circumpolar distribution and the Scandes (Fennoscandian Mountains) marks its southernmost limit in Europe. Within this area, 391 natural and 88 regulated lakes with L. arcticus have been identified, of which 87% are above the treeline. The lakes hosting L. arcticus decrease in altitude from south to north, which results from its temperature preferences. The majority of the locations are at a lower lake air temperature than 11°C which is equivalent to a water temperature near 14°C. This is assumed to be near the upper thermal threshold for L. arcticus. In lakes that exceed this average summer water temperature (1 July – 15 September), sustainable populations seem to be rare. In warmer lakes, life cycle mismatches are assumed to explain the absence of L. arcticus, most likely by affecting the embryo and juvenile stages. The distribution appears to be dichotomous, with one large northern area north of 65°N and one separated southern “island”. Only two locations of L. arcticus are known for the area between latitudes 62.88 and 64.39°N. In this part of the Scandes, the lakes are likely too warm to host L. arcticus as most of them are situated below 700 m a.s.l. This may also be the case in the northernmost region, north of 70°N, where only 11 populations are recorded. Most of the lakes in this area typically occurs below 400 m a.s.l. L. arcticus populations are sensitive to fish predation, and dense fish populations may be another stressor limiting its distribution. In contrast to water bodies in the High Arctic where L. arcticus only exists in shallow, fishless ponds, in the Scandes they co-exist with fish in 97% of the findings. Global warming has already modified the environment of the Scandes, and populations of L. arcticus are at threat in many of the small and shallow water bodies at low altitudes.

Cyclomorphosis in Daphnia magna and Ceriodaphnia reticulata (Cladocera) from northern Tunisian groundwater: influence of temperature and invertebrates?

Crustaceana ◽  
2015 ◽  
Vol 88 (10-11) ◽  
pp. 1139-1148
Author(s):  
H. Toumi ◽  
M. Bejaoui ◽  
M. Boumaiza
Keyword(s):  
Water Temperature ◽  
Daphnia Magna ◽  
Seasonal Distribution ◽  
Spine Length ◽  
Influence Of Temperature ◽  
Ceriodaphnia Reticulata ◽  
Groundwater Wells

In the present study, we investigated cyclomorphosis in two cladocerans, Daphnia magna and Ceriodaphnia reticulata, sampled from northern Tunisian groundwater (wells) during two seasons (spring and summer). Seasonal distribution of the two species was apparent, with dominance of D. magna only in spring and C. reticulata during the whole study period. Our results showed correlations between caudal spine length of D. magna and water temperature (, ), and between caudal spine length and the density of coleopteran larvae (Stictonectes escheri, Graptodytes sp., Gyrinus urinator, and Haliplus lineaticollis) (, ). In C. reticulata, we registered a correlation (, ) only between its size and the density of larvae of Ephemeroptera (Cloeon cognatum) but no correlation with water temperature was found.

Controlling factors of Region 2 field-aligned current and its relationship to the ring current: Model results

2008 ◽  
Vol 41 (8) ◽  
pp. 1234-1242 ◽  
Author(s):  
Yihua Zheng ◽  
Anthony T.Y. Lui ◽  
Mei-Ching Fok ◽  
Brian J. Anderson ◽  
Pontus C. Brandt ◽  
...  
Keyword(s):  
Ring Current ◽  
Current Model ◽  
Controlling Factors ◽  
Field Aligned Current

scholarly journals Controlling Factors of Phytoplankton Productivity in Marshes in a Hot Climate with High Seasonal Variation

2021 ◽  
Vol 9 (8) ◽  
pp. 811
Author(s):  
Fuad Ameen ◽  
Alaa I. Albueajee ◽  
Fikrat M. Hassan ◽  
Steven L. Stephenson ◽  
Ali A. Z. Douabul
Keyword(s):  
Seasonal Variation ◽  
Water Temperature ◽  
Chlorophyll A ◽  
Primary Productivity ◽  
Controlling Factors ◽  
Wet Season ◽  
Phytoplankton Productivity ◽  
Entire Area ◽  
Biological Variables ◽  
Hot Climate

In this work the Auda marsh, which is part of a system of Iraqi marshes, was sampled to assess the seasonal dynamics and controlling factors of microalgae productivity. The marshes are situated in a hot climate with high seasonal variation near the Arabian Gulf. Physicochemical and biological measurements were taken for water in three areas. Bio-optical models were constructed to describe the primary productivity and chlorophyll-a concentrations in the wet and dry seasons separately and also for the entire area of the Iraqi marshes. The models, as well as almost all measurements, showed high seasonal variation. The mean water temperature was 16 °C in the wet season and 28 °C in the dry season. An almost twofold difference was measured for turbidity and the concentrations of dissolved oxygen and chlorophyll-a for the two seasons. Chlorophyll-a appeared to be a better indicator of ecosystem conditions than primary productivity or biological oxygen demand, according to the results obtained from canonical correlation analysis. Nitrogen or phosphorous did not explain primary productivity or chlorophyll-a to an appreciable extent. Biological variables were related most strongly to water temperature and turbidity, which were the factors most important for controlling phytoplankton productivity in the marshes.

scholarly journals Effect of salinity and fish predation on zooplankton dynamics in Hooghly–Matla estuarine system, India

2016 ◽  
Vol 35 ◽  
pp. 19-28 ◽  
Author(s):  
Ujjwal Roy ◽  
Sahabuddin Sarwardi ◽  
N.C. Majee ◽  
Santanu Ray
Keyword(s):  
Fish Predation ◽  
Estuarine System ◽  
Zooplankton Dynamics

Seasonal Development of Zooplankton in the Lower River Rhine during the Period 1987–1991

1994 ◽  
Vol 29 (3) ◽  
pp. 49-51 ◽  
Author(s):  
B. van Zanten ◽  
G. M. van Dijk
Keyword(s):  
Seasonal Pattern ◽  
Controlling Factors ◽  
Seasonal Development ◽  
River Rhine ◽  
The North ◽  
Zooplankton Dynamics ◽  
The North Sea ◽  
Keratella Quadrata ◽  
Chlorophyll A Content

This paper presents some results of a five year monitoring programme on Zooplankton in the River Rhine at the Dutch sampling stations Lobith (German/Dutch border) and Maassluis (at the discharge of the river into the North Sea). During the entire period the Zooplankton composition showed an apparent seasonal pattern at both stations. This pattern was characterized by low densities during the winter and higher densities during the summer with an obvious spring peak. Zooplankton was dominated by rotifers with Brachionus angularis, B. calyciflorus, Keratella quadrata and K. cochlearis as dominant species. The possible role of environmental factors (flow rate and chlorophyll-a content) as controlling factors for Zooplankton dynamics is indicated.

scholarly journals Seasonal/Interannual Variation and Controlling Factors for Oxygen and Carbon Isotopes of Ostracod Shells Collected From a Time-Series Sediment Trap in Lake Qinghai

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhangdong Jin ◽  
Fei Zhang ◽  
Xiangzhong Li ◽  
Jin Wang ◽  
Chenyu Jin
Keyword(s):  
Time Series ◽  
Water Temperature ◽  
Seasonal Variations ◽  
Sediment Trap ◽  
Environmental Changes ◽  
High Water ◽  
Controlling Factors ◽  
Chemical Compositions ◽  
Lake Qinghai ◽  
Environmental Implications

Because the shell substance of an ostracod is derived entirely from the water body where it lives, its chemical compositions are sensitive to aquatic environment and thus have been used to reconstruct past climatic and environmental changes. However, there is controversy about the controlling factors for the different compositions of ostracod shells from various water bodies. In this study, seasonal and interannual variations in daily flux and stable oxygen-carbon isotopic compositions (δ18O, δ13C) for two species of ostracod shells (Limnocythere inopinata and Eucypris mareotica) and their controlling factors are discussed, based on ostracod shell samples collected from a time-series sediment trap from July 2010 through September 2012 and from surface sediments in Lake Qinghai, which were correlated with the state-of-the-art sensing data of the lake water. The results show that the daily flux of L. inopinata shells is an order of magnitude higher than that of E. mareotica. The δ18O and δ13C of both L. inopinata and E. mareotica shells have distinctly interannual and seasonal variations, with species differences. Interannual differences of δ18O for the two species of ostracod shells directly reflect the systematic differences of the summer water temperature between 2010 and 2012. We propose that seasonal variations of both δ18O and δ13C for the two species are affected by the precipitation of authigenic carbonates in microenvironment induced by high water temperature in summers, highlighting their environmental implications in Lake Qinghai.

Distribution of Zooplankton Populations Within and Adjacent to a Thermal Plume

1981 ◽  
Vol 38 (4) ◽  
pp. 441-448 ◽  
Author(s):  
Marlene S. Evans
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Water Temperature ◽  
Nuclear Power ◽  
Fish Predation ◽  
Vertical Displacement ◽  
Thermal Plume ◽  
Surface Layers ◽  
Fish Predators ◽  
Sampling Procedures

Zooplankton distributions in the 1-m stratum differed between ambient waters and the thermal plume of the Donald C. Cook Nuclear Power Plant. Zooplankton were most abundant in the warmest waters of the plume with the region of high densities extending over an approximate area of 0.2 to 0.3 km2. Water temperature was not a reliable indicator of alterations in zooplankton populations. Alterations were primarily due to upward vertical displacement of deep-living zooplankton. Large horizontal variability in zooplankton densities and use of conventional sampling procedures (vertically hauled nets, widely spaced stations) prevent traditionally designed monitoring programs from detecting such alterations. Zooplankton may experience indirect mortality losses in the plume if transfer of deep-living zooplankton to the surface layers makes them more visible to visual-feeding fish predators, and turbulences in the plume reduce zooplankters' ability to detect and avoid such predators.Key words: zooplankton, thermal plume, planktivorous fish, predation

Early ossicle growth in the regenerating disc of a brittle star

1994 ◽  
Vol 52 ◽  
pp. 364-365
Author(s):  
M. Shlepr ◽  
R. L. Turner
Keyword(s):  
Cell Membrane ◽  
Light Microscopy ◽  
De Novo ◽  
Current Model ◽  
Syncytium Formation ◽  
Brittle Star ◽  
Intracellular Location ◽  
Limited Volume ◽  
Tissue Calcification

Calcification in the echinoderms occurs within a limited-volume cavity enclosed by cytoplasmic extensions of the mineral depositing cells, the sclerocytes. The current model of this process maintains that the sheath formed from these cytoplasmic extensions is syncytial. Prior studies indicate that syncytium formation might be dependent on sclerocyte density and not required for calcification. This model further envisions that ossicles formed de novo nucleate and grow intracellularly until the ossicle effectively outgrows the vacuole. Continued ossicle growth occurs within the sheath but external to the cell membrane. The initial intracellular location has been confirmed only for elements of the echinoid tooth.The regenerating aboral disc integument of ophiophragmus filograneus was used to test the current echinoderm calcification model. This tissue is free of calcite fragments, thus avoiding questions of cellular engulfment, and ossicles are formed de novo. The tissue calcification pattern was followed by light microscopy in both living and fixed preparations.

Ring current model of the naphthalene molecule

1997 ◽  
Vol 92 (3) ◽  
pp. 609-617 ◽  
Author(s):  
RICCARDO ZANASI ◽  
PAOLO LAZZERETTI
Keyword(s):  
Ring Current ◽  
Current Model ◽  
Naphthalene Molecule
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