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- Leandro, S. M., et al.
(författare)
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Copepod production estimated by combining in situ data and specific temperature-dependent somatic growth models
- 2014
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 741:1, s. 139-152
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Tidskriftsartikel (refereegranskat)abstract
- Although growth in adult copepods is frequently assumed to be similar to juvenile growth, some evidence have pointed out that under in situ conditions, it can be lower, with, as a consequence, underestimation of secondary production. In addition, under field conditions, juvenile growth in copepods is close to maximum rates estimated at food-saturated conditions. Based on previous assumptions, this study aimed to test the applicability of a new approach for copepod production estimate, derived from temperature-dependent growth models and in situ data, such as seawater temperature and copepod biomass. For this purpose, site-specific copepod juvenile growth models, defined for Acartia tonsa and A. clausi populations from a Southern European estuary (Canal de Mira, Ria de Aveiro, Portugal), were used and copepod biomass was taken from zooplankton samples collected during 2 years at six sampling stations. By comparing the obtained results with published data, the feasibility of the approach for copepod secondary production estimates and its applicability in worldwide marine ecosystems was confirmed. Future studies should combine the estimates of adult and juvenile production in order to evaluate its relative contribution and to obtain a more precise estimate of secondary production.
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- Calliari, Danilo, 1969, et al.
(författare)
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Instantaneous salinity reductions affect the survival and feeding rates of the co-occurring copepods Acartia tonsa Dana and A-clausi Giesbrecht differently
- 2008
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Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981. ; 362:1, s. 18-25
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Tidskriftsartikel (refereegranskat)abstract
- Salinity variability at short time scales constitutes a severe restriction to marine life in coastal and estuarine ecosystems. In these environments zooplankters may experience rapid salinity variations due to diverse processes, yet lethal or sub-lethal responses to such changes have been scarcely studied. We assessed short-term (12 h) survival and time-integrated clearance (F; mL ind(-1) h(-1)) and ingestion rates (1, mu gC ind(-1) h(-1)) after 1, 2, 4, 8 and 12 h of two widespread and abundant coastal copepods, Acartia tonsa and A. clausi, subjected to instant salinity changes from 32 PSU to 26, 20,14, 8 and 4 PSU (A. tonsa) and from 32 to 26, 20 and 14 PSU (A. clausi). We expected that A. tonsa, which occur naturally in environments where sharp salinity gradients are common would tolerate wider salinity changes than A. clausi, which less frequently encounter sharp gradients in nature. For A. tonsa mortality for the extreme haline shock (change from 32 to 4 PSU) was 31%, whereas A. clausi reached 22% Mortality already at a change from 32 to 14 PSU; in comparison, mortality for A. tonsa at the 32/14 PSU treatment was only 3%. F and I decreased significantly at extreme treatments, and the total clearance in experimental bottles with salinity shocked animals (F-tot, mL h(-1)) was only 5% of rates measured in non-shocked control bottles for A. tonsa (32/4 PSU change) and 20% for A. clausi (32/14 PSU change); corresponding total ingestion (I-tot, mu gC h(-1)) represented 9.5% of that in control bottles for A. tonsa and 24% for A. clausi. In comparison, the 32/14 PSU treatment did not affect either clearance or ingestion rates in A. tonsa. Results suggest that in the field A. tonsa is not likely to suffer significant mortalities due to sudden salinity reductions in the Surrounding medium - except under extreme circumstances- while A. clausi cannot tolerate changes > 18 PSU. However, in both species feeding activity could be severely compromised by salinity reductions. The decreased feeding rate may have direct implications for processes ranging from energy acquisition at individual level to organic matter transfers at ecosystem level and thus deserves more attention in experimental studies and population modelling. (C) 2008 Elsevier B.V. All rights reserved.
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| 11. |
- Calliari, Danilo, 1969, et al.
(författare)
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Salinity modulates the energy balance and reproductive success of co-occurring copepods Acartia tonsa and A-clausi in different ways
- 2006
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Ingår i: Marine Ecology-Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 312, s. 177-188
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Tidskriftsartikel (refereegranskat)abstract
- We assessed metabolic balance, RNA content, and egg hatching success (EHS) in Acartia tonsa and A. clausi over a wide salinity range (2 to 33 and 16 to 33, respectively). For A. tonsa, the energy partitioning between ingestion, production and respiration was relatively constant with small differences in gross growth efficiency (GGE) and cost of growth (CG). In contrast, A. clausi exhibited significantly reduced ingestion and GGE, and highly elevated CG at salinities <= 20. In both species, RNA levels mirrored egg production. EHS was generally high in both species, but decreased by 80% for A. clausi at 16. These results contribute to the understanding of distribution patterns of both species along salinity gradients. The observed responses would allow the dominance of A. tonsa at low salinities, although its higher energetic requirement and feeding activity subject it to stronger predation pressure than competing A. clausi.
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- Juul-Pedersen, T., et al.
(författare)
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Sedimentation following the spring bloom in Disko Bay, West Greenland, with special emphasis on the role of copepods
- 2006
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Ingår i: Marine Ecology-Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 314, s. 239-255
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Tidskriftsartikel (refereegranskat)abstract
- The sedimentation of particulate organic material was investigated in Disko Bay, West Greenland, during June 2001. Post spring-bloom conditions were encountered, with seasonally decreasing phytoplankton biomass associated with the pycnocline. Calanus finmarchicus, C. glacialis, and C. hyperboreus dominated the zooplankton community, comprising up to 88% of the copepod biomass. Faecal pellet production by C. finmarchicus and C. glacialis was positively correlated to the available food (chlorophyll a > 10 mu m). Results from short-term sediment trap deployments (6 h) showed that particulate organic carbon (POC) sedimentation from the euphotic zone was, on average, 628 mg C m(-2) d(-1), with copepod faecal pellets contributing, on average, 29% of this amount. The faecal pellet contribution to the vertical sinking export of POC was equivalent to that of phytoplankton and amorphous detritus. Yet, on average, 35% of the copepod faecal pellet production was retained within the euphotic zone. The POC: PON (particulate organic nitrogen) ratio of the suspended material in the euphotic zone (8.1 +/- 0.4) was comparable to that of the material collected in the sediment traps just below the euphotic zone (8.0 +/- 0.9). In addition, the daily loss rates of POC and PON within each sampling depth were similar, and the carbon to nitrogen ratio in the sediment traps did not change with depth. These results indicate that the pelagic system had a low retention efficiency of nitrogen just after the spring bloom.
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- Thor, Peter, 1965, et al.
(författare)
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Post-spring bloom community structure of pelagic copepods in the Disko Bay, Western Greenland
- 2005
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Ingår i: Journal of Plankton Research. - : Oxford University Press (OUP). - 0142-7873 .- 1464-3774. ; 27:4, s. 341-356
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Tidskriftsartikel (refereegranskat)abstract
- Community structure of pelagic copepods was investigated in the upper 200 m in the Disko Bay, Western Greenland, during the post-spring bloom period in June, 2001. This was the first study of the copepod community in West Greenland coastal waters sampled using smaller mesh sizes (50 mu m as opposed to 200 mu m). The mesozooplankton was dominated by copepods who constituted 82% of the total abundance and 95% of the total mesozooplankton biomass (> 50 mu m). Nauplii of Calanus, Pseudocalanus and Oithona dominated by number and the copepodites and adults were dominated by Oithona spp., Oncaea sp., Pseudocalanus sp., harpacticoids, Calanus finmarchicus, C. glacialis, and C. hyperboreus. Multivariate tests showed that the species/stage abundance composition of copepods changed significantly with depth. With one exception, all depth intervals showed unique significantly different compositions. Accordingly, the copepod community structure was influenced primarily by depth rather than by chlorophyll a concentration. Factors other than herbivorous grazing, such as omnivory, predator avoidance or association to marine snow aggregates of specific species, may have influenced the depth distribution of the total copepod community in the Disko Bay. Nevertheless, subsequent Pearson product moment correlations showed positive significant correlations between the vertical distribution of the three Calanus spp. and Pseudocalanus spp. and chlorophyll a concentrations, which points towards these species as prime components in the classic diatom-copepod food chain.
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| 20. |
- Tiselius, HG, et al.
(författare)
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Guidelines on urolithiasis
- 2001
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Ingår i: European urology. - : Elsevier BV. - 0302-2838 .- 1421-993X. ; 40:4, s. 362-371
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Tidskriftsartikel (refereegranskat)
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| 22. |
- Tiselius, Peter, 1958, et al.
(författare)
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Functional response of Oikopleura dioica to house clogging due to exposure to algae of different sizes
- 2003
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Ingår i: Marine Biology. - 0025-3162. ; 142:2, s. 253-261
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Tidskriftsartikel (refereegranskat)abstract
- The functional response of the appendicularian Oikopleura dioica was investigated with a unialgal diet (Isochrysis galbana, 0-1,600 mug Cl-1) and with additions of specific concentrations of algae either smaller than the incurrent filter mesh size (Rhodomonas baltica, 90 mug Cl-1; Thalassiosira weissflogii, 60 mug Cl-1) or larger algae (Ceratium lineatum, 8 mug Cl-1; C. tripos, 52 mug C l(-1)). Clearance ranged from 0.13 to 3.3 ml mug C-1 h(-1) and followed a Michaelis-Menten curve corresponding to a maximum filtration rate (particles collected by both animal and house), FRmax = 164 ng C mug C-1 h(-1) and K-m = 64 mug C l(-1). Maximum pellet production was 9 pellets ind(-1) h(-1) and occurred at 100 mugC (-1). Pellet production was proportional to filtration rate below this level, but declined at higher concentrations. House production ranged from 0.5 to 5.5 houses ind(-1) day(-1) and the corresponding curve fit resulted in H-max = 4.6 houses ind(-1) day(-1) and K-m house = 32 mug Cl-1. Addition of edible small algae caused increased internal clogging of the houses, evidenced by significantly higher pigment concentrations in abandoned houses than in houses produced with I.. galbana as a single food. House production was not affected. In contrast, larger algae caused a significantly higher house production, but the algae were not collected on the houses. Increased levels of edible algae will not have negative effects on O. dioica at ecologically realistic concentrations. Ambient bloom concentrations of larger algae may, however, have a negative effect on the growth of O. dioica populations, owing to the compensatory increased house production.
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| 24. |
- Tiselius, Peter, 1958, et al.
(författare)
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High reproduction, but low biomass: mortality estimates of the copepod Acartia tonsa in a hyper-eutrophic estuary
- 2008
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Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7790 .- 1864-7782. ; 2:1, s. 93-103
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Tidskriftsartikel (refereegranskat)abstract
- Production, abundance and mortality of the copepod Acartia tonsa were studied for a period of 9 d in a hyper-eutrophic estuary, Mariager Fjord, Denmark. The estuary is characterised by oxygen-depleted and often sulphidic bottom water, and a relatively sparse mesozooplankton community with low species diversity. During the study, an intense phytoplankton bloom consisting mainly of the diatom Skeletonema costatum developed with chlorophyll a concentrations reaching 46 mu g l(-1). Egg production rate (EPR) in A. tonsa ranged from 30 to 65 eggs female(-1) d(-1), and egg hatching success was > 90 %, yet the abundance of copepods remained low (1 to 3 nauplii l(-1), 0.3 to 1.5 copepodites l(-1)). Calculated daily copepod mortality ranged from 18 % for nauplii, 16 % for Copepodite Stage C 1, up to 70 % for C2 and C3, then declining for older stages. The vertical distribution of copepodites in relation to the depth range of mussel beds suggests strong predation by suspension-feeding Mytilus edulis at depths of 5 to 10 m. Moreover, anoxia and the presence of sulphide in deep water, which prevented hatching of A. tonsa eggs and decreased the survivorship of older life stages sinking below 20 m depth, further contributed to the low copepod abundance.
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| 25. |
- Tönnesson, Kajsa, 1971, et al.
(författare)
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Grazing impact of Oikopleura dioica and copepods on an autumn plankton community
- 2005
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Ingår i: Marine Biology Research. - : Informa UK Limited. - 1745-1000 .- 1745-1019. ; 1:5, s. 365-373
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Tidskriftsartikel (refereegranskat)abstract
- Copepods and appendicularians are major grazers in the pelagic environment. They have different retention efficiencies for prey and may therefore exert a variable grazing pressure on the spectrum of pico- to micro-plankton. We determined clearance rates of both groups at one station during 24 h in the Gullmar fjord, west Sweden, in autumn 1999. Total potential prey biomass ranged from 75 mu g C l(-1) at the surface to 14 mu g C l(-1) at 30 m with a dominance of larger dinoflagellates (10-25 mu m athecate species and Gymnodinium /Gyrodinium sp.) and the pennate diatom Pseudo -nitzschia sp. Grazer biomass was dominated by copepods (Acartia clausi, Paracalanus parvus) and appendicularians (Oikopleura dioica). O. dioica showed non-selective clearance rates of 0.7-1.8 ml mu g C-1 h(-1) on most diatoms, flagellates and ciliates, whereas Pseudo -nitzschia sp. and dinoflagellates and ciliates > 25 mu m were not removed by O. dioica. Appendicularian grazing impact was 0.06% d(-1) on the phytoplankton and 0.4% d(-1) on bacterial biomass. Despite a seven-fold higher biomass, the grazing impact of copepods on phytoplankton biomass was only 0.28% d(-1) indicating that O. dioica had a proportionally greater impact and, in contrast to copepods, also utilised bacteria. The low observed grazing impact was due to a low grazer biomass and a prey community largely unavailable to the investigated grazers.
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