Ecological investigations of the zooplankton community of balsfjorden, northern norway: The genital system in Calanus finmarchicus and the role of gonad development in overwintering strategy

1981 ◽  
Vol 63 (2) ◽  
pp. 159-164 ◽  
Author(s):  
K. S. Tande ◽  
C. C. E. Hopkins

2000 ◽  
Vol 60 (1) ◽  
pp. 101-111 ◽  
Author(s):  
F. L. do R. M. STARLING

Zooplankton community from six lacustrine ecosystems located in Federal District (Central Brazil) was studied based on samples collected during the dry season (July to September). A total of 71 taxa were recorded: 44 rotifers, 17 cladocerans and 10 copepods. The highest number of zooplankton species was recorded in oligotrophic Bonita Pond (32 species) and the lowest number in hypertrophic waste stabilisation ponds (7 species). This tendency of decreasing the diversity with increasing trophic level was consistent with a cluster analysis of the samples based on Sorensen index of similarity. From the overall similarity dendrogram, two groups of ecosystems were distinguished: one containing the natural ponds Bonita and Formosa and the other comprising the reservoirs Santa Maria, Descoberto and Paranoá. The role of morphometric features in determining the zooplankton community in such lacustrine ecosystems was also discussed.



2018 ◽  
Vol 18 (2) ◽  
Author(s):  
Muhammad Junaidi ◽  
Nurliah Nurliah ◽  
Fariq Azhar

ABSTRAKMengingat peranan zooplankton dalam ekosistem perairan sangat penting, maka dilakukan penelitian dengan tujuan untuk menganalisis struktur komunitas zooplankton yang meliputi jenis, kelimpahan, dan indek ekologi, dan  kaitan  distribusi zooplankton dan kualitas perairan di Perairan Kabupaten Lombok Utara. Pengumpulan data dirancang dengan sistem informasi geografis (SIG) pada 23 stasiun pengamatan yang ditentukan dengan teknik acak sederhana.  Hasil penelitian menunjukkan bahwa jenis dan kelimpahan zooplankton yang ditemukan di Perairan Kabupaten Lombok Utara cukup bervariasi dengan jumlah genus  sebanyak 9 yang terbagi  dari  5 kelas.  Berdasarkan perhitungan indeks ekologi menunjukkan bahwa struktur  komunitas zooplankton dalam kategori perairan yang kurang stabil. Kelimpahan dan indeks ekologi zooplankton  dipengaruhi oleh kondisi lingkungan (fisik-kimia) perairan antara lain  kecerahan, pH dan oksigen terlarut. Kata kunci : zooplankton,  struktur komunitas, kualitas perairan, kelimpahanABSTRACTConsidering that the role of zooplankton in aquatic ecosystems is very  important, research is carried out with the aim of analyzing zooplankton community structure which includes the type, abundance, and ecological index, and the relation of zooplankton distribution and water quality in North Lombok Regency Waters. Data collection was designed with a geographical information system (GIS) on 23 observation stations that were determined by simple random techniques. he results of this study indicate that the type and abundance of zooplankton found in the waters of North Lombok Regency are quite varied with the number of genus as many as 9 which are divided into 5 classes. Based on the calculation of the ecological index shows that the zooplankton community structure is in the category of less stable waters. The abundance and ecological index of zooplankton is influenced by the environmental (physical-chemical) conditions of the waters including brightness, pH and dissolved oxygen. Keywords: zooplankton, community structure, water quality, abundance 



2016 ◽  
Vol 13 (10) ◽  
pp. 3131-3145 ◽  
Author(s):  
Brian P. V. Hunt ◽  
Sophie Bonnet ◽  
Hugo Berthelot ◽  
Brandon J. Conroy ◽  
Rachel A. Foster ◽  
...  

Abstract. In oligotrophic tropical and subtropical oceans, where strong stratification can limit the replenishment of surface nitrate, dinitrogen (N2) fixation by diazotrophs can represent a significant source of nitrogen (N) for primary production. The VAHINE (VAriability of vertical and tropHIc transfer of fixed N2 in the south-wEst Pacific) experiment was designed to examine the fate of diazotroph-derived nitrogen (DDN) in such ecosystems. In austral summer 2013, three large ( ∼  50 m3) in situ mesocosms were deployed for 23 days in the New Caledonia lagoon, an ecosystem that typifies the low-nutrient, low-chlorophyll environment, to stimulate diazotroph production. The zooplankton component of the study aimed to measure the incorporation of DDN into zooplankton biomass, and assess the role of direct diazotroph grazing by zooplankton as a DDN uptake pathway. Inside the mesocosms, the diatom–diazotroph association (DDA) het-1 predominated during days 5–15 while the unicellular diazotrophic cyanobacteria UCYN-C predominated during days 15–23. A Trichodesmium bloom was observed in the lagoon (outside the mesocosms) towards the end of the experiment. The zooplankton community was dominated by copepods (63 % of total abundance) for the duration of the experiment. Using two-source N isotope mixing models we estimated a mean  ∼  28 % contribution of DDN to zooplankton nitrogen biomass at the start of the experiment, indicating that the natural summer peak of N2 fixation in the lagoon was already contributing significantly to the zooplankton. Stimulation of N2 fixation in the mesocosms corresponded with a generally low-level enhancement of DDN contribution to zooplankton nitrogen biomass, but with a peak of  ∼  73 % in mesocosm 1 following the UCYN-C bloom. qPCR analysis targeting four of the common diazotroph groups present in the mesocosms (Trichodesmium, het-1, het-2, UCYN-C) demonstrated that all four were ingested by copepod grazers, and that their abundance in copepod stomachs generally corresponded with their in situ abundance. 15N2 labelled grazing experiments therefore provided evidence for direct ingestion and assimilation of UCYN-C-derived N by the zooplankton, but not for het-1 and Trichodesmium, supporting an important role of secondary pathways of DDN to the zooplankton for the latter groups, i.e. DDN contributions to the dissolved N pool and uptake by nondiazotrophs. This study appears to provide the first evidence of direct UCYN-C grazing by zooplankton, and indicates that UCYN-C-derived N contributes significantly to the zooplankton food web in the New Caledonia lagoon through a combination of direct grazing and secondary pathways.



2017 ◽  
Vol 75 (7) ◽  
pp. 2342-2354 ◽  
Author(s):  
Johanna Myrseth Aarflot ◽  
Hein Rune Skjoldal ◽  
Padmini Dalpadado ◽  
Mette Skern-Mauritzen

Abstract Copepods from the genus Calanus are crucial prey for fish, seabirds and mammals in the Nordic and Barents Sea ecosystems. The objective of this study is to determine the contribution of Calanus species to the mesozooplankton biomass in the Barents Sea. We analyse an extensive dataset of Calanus finmarchicus, Calanus glacialis, and Calanus hyperboreus, collected at various research surveys over a 30-year period. Our results show that the Calanus species are a main driver of variation in the mesozooplankton biomass in the Barents Sea, and constitutes around 80% of the total. The proportion of Calanus decreases at low zooplankton biomass, possibly due to a combination of advective processes (low C. finmarchicus in winter) and size selective foraging. Though the Calanus species co-occur in most regions, C. glacialis dominates in the Arctic water masses, while C. finmarchicus dominates in Atlantic waters. The larger C. hyperboreus has considerably lower biomass in the Barents Sea than the other Calanus species. Stages CIV and CV have the largest contribution to Calanus species biomass, whereas stages CI-CIII have an overall low impact on the biomass. In the western area of the Barents Sea, we observe indications of an ongoing borealization of the zooplankton community, with a decreasing proportion of the Arctic C. glacialis over the past 20 years. Atlantic C. finmarchicus have increased during the same period.





2010 ◽  
Vol 57 (11) ◽  
pp. 1465-1473 ◽  
Author(s):  
Frank Gaardsted ◽  
Meng Zhou ◽  
Vladimir Pavlov ◽  
Alexey Morozov ◽  
Kurt S. Tande


2014 ◽  
Vol 65 (9) ◽  
pp. 791 ◽  
Author(s):  
R. J. Wasserman ◽  
T. J. F. Vink ◽  
R. Kramer ◽  
P. W. Froneman

Although predation has been identified as an important community driver, the role of predator diversity in structuring estuarine zooplankton has not been assessed. As such, we investigated the effects of two different zooplanktivorous fish species on the estuarine zooplankton community during a 12-day mesocosm study. Three experimental treatments were established, whereby natural zooplankton communities were subject to either (1) no predatory pressure, (2) predation by a pelagic predator (Monodactylus falciformis) or (3) predation by a hyper-benthic predator (Glossogobius callidus). The pelagic feeding M. falciformis fed largely on the numerically dominant mid-water copepod species, Paracartia longipatella. In contrast, the hyper-benthic fish had a greater predatory impact on the less numerically dominant copepod, Pseudodiaptomus hessei, which demonstrates strong diel vertical migration. Variations in prey-population regulation are ascribed to the distinct behavioural differences of the predators, and mediated by the differences in behaviour of the copepod species.



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