| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- Rodriguez-Grana, Laura, 1969, et al.
(författare)
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Gender specific ageing and non-mendelian inheritance of oxidative damage in marine copepods
- 2010
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Ingår i: Marine Ecology Progress Series. - 0171-8630. ; 401, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- Ageing in the marine pelagic copepod Acartia tonsa results in decreased feeding and production rates associated with an increase in the accumulation of protein oxidative damage, as predicted by the oxidative stress hypothesis. In laboratory experiments, we estimated sex-specific ageing effects on feeding and oxidative damage and on egg production rates of adult females. We also determined maternal effects on offspring by measuring egg hatching success and oxidative damage of nauplii from mothers of different ages. Males manifested more oxidative damage with age than females, providing an alternative explanation for the shorter life span in males. Older females produced fewer offspring, and nauplii with higher protein oxidative damage, than younger females. This study forms an empirical basis to link ageing, life span, sex differences and maternal fitness in animals that also reflects natural copepod population dynamics. Individual ageing processes and the resulting age structure in the population modulate mortality risk, parental effects on offspring performance, reproductive investment, and pelagic energy fluxes.
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| 5. |
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| 6. |
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| 7. |
- 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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| 8. |
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| 9. |
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| 10. |
- Broms, F., et al.
(författare)
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Effects of temperature and body size on the clearance rate of Oikopleura dioica
- 2003
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Ingår i: Journal of Plankton Research. - 0142-7873. ; 25:5, s. 573-577
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Tidskriftsartikel (refereegranskat)abstract
- The effects of temperature and body size on the clearance rate of the appendicularian Oikopleura dioica were investigated. The clearance rate increased with the trunk length of the animals according to a power function with exponent 3.2 +/- 0.17 (range 2.9-3.8). The intercepts of the three regressions were significantly different with the highest rates at 20degreesC, corresponding to a Q(10), value of 1.78 (10-20degreesC).
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| 11. |
- Calliari, D., et al.
(författare)
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Density dependent grazing rates in a natural microzooplankton community
- 2019
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 622, s. 83-92
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Tidskriftsartikel (refereegranskat)abstract
- Density dependence is a common phenomenon that affects individual performance in a wide range of organisms. Negative density dependence involves diminished individual rates, e.g. feeding and growth, under high organismal concentration. Microzooplankton (µZ) are key consumers in marine ecosystems and their grazing is frequently estimated by the dilution technique, which involves experimental manipulation of population concentrations of both grazer and prey. However, the potential interference of density dependent processes on grazing estimates has not been evaluated in the general context of µZ ecology, nor in the specific context of the dilution technique. Density dependent effects on µZ grazing rates were evaluated for a natural community of grazers in the Gullmar Fjord (Skagerrak, Sweden) across a wide but realistic range of µZ densities and under controlled algal prey concentrations. Net algal growth rates (k), grazing rate of the µZ community (G), and per capita grazing rates (SG) by the components of the µZ community were estimated based on algal cell counts and chlorophyll a (as metrics for prey concentration) and µZ counts (as a measure of predator concentration). The 3 responses (k, G and SG) showed clear evidence of negative density dependence under moderate and high levels of µZ concentrations. Results imply that negative density dependent effects on µZ grazing rates may actually occur in marine ecosystems. © Inter-Research 2019.
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| 12. |
- Calliari, Danilo, 1969, et al.
(författare)
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Feeding and reproduction in a small calanoid copepod: Acartia clausi can compensate quality with quantity
- 2005
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Ingår i: Marine Ecology-Progress Series. - 0171-8630. ; 298, s. 241-250
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Tidskriftsartikel (refereegranskat)abstract
- We analyzed the feeding, egg production rate (EPR), and the egg hatching success (EHS) of resulting eggs of adult Acartia clausi subject to realistic food levels (100 mu g C l(-1)) of 7 algae. Feeding was maximum (ca. 20 ml ind.(-1) d(-1)) with Thalassiosira weissflogii and minimum (ca. 0 ml ind.(-1) d(-1)) with Dunaliella tertiolecta and Prymnesium parvum. EPR was highest with T weissflogii, Tetraselmis sp., Rhodomonas sp., and Ditylum brightwellii (21 to 26 eggs ind.(-1) d(-1)) and moderate with Prorocentrum minimum (15 eggs ind.(-1) d(-1)). EHS was highest in R minimum (84%), followed by Rhodomonas sp. (80%), D, brightwellii (60%), T weissflogii (52%) and Tetraselmis sp. (40%). Supplementary nutritional effects (higher EHS and gross growth efficiency) appeared when A. clausi fed on mixtures of algae with contrasting effects on EPR and EFIS (T weissflogii and P. minimum) offered as mixed suspensions, or alternating between unialgal suspensions on a 12:12 h basis. However, realized fecundity (RF) was fairly stable for most single and mixed diets (range 12.3 to 17.3 nauplii female(-1) d(-1)), with the exception of Tetraselmis sp. (8.9 nauplii female(-1) d(-1)). Such stable RF was attained by compensating low EFIS with enhanced feeding and EPR, and consequently lower population growth efficiency. That represents a strategy with a high cost in terms of metabolism and predation risk.
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| 13. |
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| 14. |
- Dinasquet, Julie, et al.
(författare)
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Cascading effects of the ctenophore Mnemiopsis leidyi on the planktonic food web in a nutrient-limited estuarine system
- 2012
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Ingår i: Marine Ecology Progress Serie. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 460, s. 49-61
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Tidskriftsartikel (refereegranskat)abstract
- Increasing biomasses of gelatinous zooplankton presumably have major implications for the structure and function of marine food webs at large; however, current data on lower trophic levels are scarce, as most studies have focused on the immediate effects on zooplankton and fish larvae only. We examined the short-term impact of larvae and adults of the invasive ctenophore Mnemiopsis leidyi on a summer planktonic food web in the estuarine southern Baltic Sea, with special emphasis on the microbial loop. Grazing by M. leidyi reduced the mesozooplankton biomass, followed by increased dinoflagellate biomass in treatments with M. leidyi. While chlorophyll a increased most in the treatments with M. leidyi, small phytoplankton and ciliates decreased in all treatments. M. leidyi had a slight effect on bacterial abundance, but not on bacterial production, ectoenzymatic activities, or community composition. Undetectable levels of phosphate and a gradual accumulation of dissolved organic carbon during the experiment suggested a malfunctioning microbial loop scenario. The experiment shows that direct and indirect short-term effects of M. leidyi on the estuarine food web are limited to higher trophic levels and indicates that top-down and bottom-up consequences of M. leidyi expansions on the microbial loop will likely depend on local nutrient conditions.
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| 15. |
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| 16. |
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| 17. |
- Hansen, Benni W., et al.
(författare)
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In situ and experimental evidence for effects of elevated pH on protistan and metazoan grazers
- 2019
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Ingår i: Journal of Plankton Research. - : Oxford University Press (OUP). - 0142-7873 .- 1464-3774. ; 41:3, s. 257-271
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Tidskriftsartikel (refereegranskat)abstract
- Plankton succession was studied in a hyper-eutrophic stratified estuary, Mariager Fjord, Denmark. Above the pycnocline (15 m) pH increased from 8.5 to 9.2 and the oxygen increased to super saturation after 5 d of sunny weather due to high primary production. The protistan grazers were dominated by heterotrophic dinoflagellates and mixotrophic and heterotrophic ciliates. Metazooplankton was dominated by meroplankton, rotifers and the copepod, Acartia tonsa, all with a relatively low biomass. Cirriped nauplii occupied the upper strata while polychaete larvae populated the whole water column. Bivalve larvae occurred occasionally above the pycnocline even at very high pH. In pH challenge experiments, the mixotrophic ciliate Mesodinium rubrum was the least pH tolerant species, followed by Strombidium spp., which did not cope well with seawater pH > 8.5. Some heterotrophic dinoflagellates were more tolerant with net growth at pH > 9. The predominant rotifer Synchaeta sp. tolerated up to pH 9.5 and the copepod survived pH 10 but stopped producing eggs at pH 9.5 with unaffected egg hatching success. The polychaete and cirriped larvae tolerated pH 9.5, but bivalve larvae showed decreased survival already at pH 8.5. In situ distribution patterns and pH challenge experiments suggest that pH indeed contribute to structuring zooplankton distribution.
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| 18. |
- Haraldsson, Matilda, 1980, et al.
(författare)
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Environmental constraints of the invasive Mnemiopsis leidyi in Scandinavian waters
- 2013
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590. ; 58:1, s. 37-48
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Tidskriftsartikel (refereegranskat)abstract
- We studied the seasonal dynamics of the invasive ctenophore Mnemiopsis leidyi over its distribution range from Skagerrak into the Baltic Proper during 1 yr and related this to ambient physical and biological variables. The appearance of M. leidyi was sporadic in the Baltic Proper, with 60-fold lower abundance than in the Skagerrak and Kattegat (mean 0.02 individual m−3 and 1.16 individual m−3, respectively). M. leidyi typically resided above the halocline (10–20 m depth), except in the Baltic Proper where they were found deeper. Smaller size classes were underrepresented in the Baltic Proper, indicating failed reproduction or high mortality of the younger life stages. Ninety percent of the M. leidyi were observed at salinities of 22–29 and 75% of the individuals in water masses warmer than 11°C, i.e., typical late summer to autumn temperatures. Results of a Generalized Additive Model (GAM) indicate that the spatio-temporal distribution of M. leidyi might be explained by advection of M. leidyi from the Skagerrak and Kattegat area to the Baltic Proper. We conclude that the low salinity (< 9) of the Baltic Proper is likely to restrict successful reproduction and establishment of M. leidyi and that the advection of individuals from higher saline source areas sustained the observed Baltic Proper occurrence.
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| 19. |
- Haraldsson, Matilda, 1980, et al.
(författare)
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Evidence of diel vertical migration in Mnemiopsis leidyi
- 2014
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- The vertical distribution and migration of plankton organisms may have a large impact on their horizontal dispersal and distribution, and consequently on trophic interactions. In this study we used video-net profiling to describe the fine scale vertical distribution of Mnemiopsis leidyi in the Kattegat and Baltic Proper. Potential diel vertical migration was also investigated by frequent filming during a 24-hour cycle at two contrasting locations with respect to salinity stratification. The video profiles revealed a pronounced diel vertical migration at one of the locations. However, only the small and medium size classes migrated, on average 0.85 m h-1, corresponding to a total migration distance of 10 m during 12 h. Larger individuals (with well developed lobes, approx. >27 mm) stay on average in the same depth interval at all times. Biophysical data suggest that migrating individuals likely responded to light, and avoided irradiance levels higher than approx. 10 µmol quanta m-2 s-1. We suggest that strong stratification caused by low surface salinity seemed to prohibit vertical migration.
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| 20. |
- Haraldsson, Matilda, 1980, et al.
(författare)
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The relationship between fish and jellyfish as a function of eutrophication and water clarity
- 2012
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 471, s. 73-85
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Tidskriftsartikel (refereegranskat)abstract
- There is a concern that blooms of cnidarians and ctenophores, often referred to as jellyfish, are increasing in frequency and intensity worldwide and that there is a shift from fish- to jellyfish-dominated systems. We present an idealized analysis of the competitive relationship between zooplanktivorous jellyfish that is based on a generic model, termed ‘Killing the Winner’ (KtW), for the coexistence of 2 groups utilizing the same resource. Tactile predation by jellyfish makes them less dependent on water optics than fish using vision, and we modified the KtW model to account for this particular trait difference. Expectations of the model are illustrated by use of observations from the Baltic Sea. The model predicts a general succession on how mass of the system distributes when going from an oligotrophic to a eutrophic system. Initially the mass of the system accumulates at the level of the common resource (zooplankton) and planktivorous fish (sprat/herring). At one point, with increased eutrophication, mass starts to accumulate at the level of the top predator (cod) and at a later point, at the level of the jellyfish. For those organisms utilizing vision (fishes) an optimal degree of eutrophication and water clarity is predicted due to a 2-sided effect of eutrophication.
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| 21. |
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| 22. |
- Jönander, Christina, 1990, et al.
(författare)
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Exposure to closed-loop scrubber washwater alters biodiversity, reproduction, and grazing of marine zooplankton
- 2023
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Ingår i: Frontiers in Marine Science. - 2296-7745. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Shipping is a large industry responsible for atmospheric emissions of hazardous substances including SOX, NOX, and particulate matter. Many ships have installed exhaust gas cleaning systems (scrubbers) to remove primarily SOX from the exhaust, but the hazardous substances are instead transferred to the water used in the scrubbing process. Ships with closed-loop scrubbers recirculate the water but can still discharge around 126-150 m3 directly to the surrounding marine environment every day. The discharged water contains metals and organic substances, such as polycyclic aromatic hydrocarbons, that are known to be toxic to marine zooplankton. Here we show that closed-loop scrubber washwater is toxic to communities of marine mesozooplankton at our lowest tested dilution, 1.5% (v/v), and affects survival, reproduction, diversity, and ability to predate on microzooplankton. The cumulative toxic unit of the undiluted closed-loop scrubber washwater was estimated to 17, which indicates that the water could be toxic at levels below what was tested in this study. Among all detected substances, vanadium, copper, benzo[ghi]perylene, nickel, and zinc were identified as toxicity-driving substances in the order listed. Closed-loop scrubber washwater has been shown to affect development and survival in single species of copepods, but here we find evidence of toxicity at the community level, irrespective of seasonal community structure, and that the exposure has potential to disrupt the interactions between trophic levels in the pelagic food web. We show that the closed-loop scrubber washwater cause both lethal and sublethal effects in marine zooplankton, due to contaminants, some of which are persistent in the marine environment.
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| 23. |
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| 24. |
- Kiorboe, T., et al.
(författare)
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Intensive aggregate formation with low vertical flux during an upwelling-induced diatom bloom
- 1998
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Ingår i: Limnology and Oceanography. - 0024-3590. ; 43:1, s. 104-116
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Tidskriftsartikel (refereegranskat)abstract
- The surfaces of most pelagic diatoms are sticky at times and may therefore form rapidly settling aggregates by physical coagulation. Stickiness and aggregate formation may be particularly adaptive in upwelling systems by allowing the retention of diatom populations in the vicinity of the upwelling center. We therefore hypothesized that upwelling diatom blooms are terminated by aggregate formation and rapid sedimentation. We monitored the development of a maturing diatom (mainly Chaetoceros spp.) bloom in the Benguela upwelling current during 7 d in February. Chlorophyll concentrations remained consistently high during the observation period (similar to 500 mg Chi m(-2)) and phytoplankton grew at an average specific rate of 0.25 d(-1). The diatoms were extraordinarily sticky, with stickiness coefficients of up to 0.40, which is the highest ever recorded for field populations. Combined with estimates of turbulent shear in the ocean such stickiness coefficients predict very high specific coagulation rates (0.3 d(-1)). In situ video observation demonstrated the occurrence of abundant diatom aggregates with surface water concentrations between 1,000 and 3,000 ppm. Despite the very high concentration of aggregates, vertical fluxes of phytoplankton were very low, with fractional losses <0.005 d(-1), and the aggregates thus seemed to be near neutrally buoyant. Losses due to copepod grazing were also low (similar to 0.025 d(-1)). Most of the aggregates were colonized by the heterotrophic dinoflagellate Noctiluca scintillans that feed upon diatoms in the aggregates. The system appeared to be in near steady state; specific diatom growth rate, coagulation rate, and loss rate due to N, scintillans feeding were all of the same magnitude (0.25-0.3 d(-1)) and the latter two varied in concert. Our observations provide only partial support for the population retention hypothesis because aggregate buoyancy and N, scintillans grazing efficiently reduced the vertical flux of aggregates in this system.
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| 25. |
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| 26. |
- Kiorboe, T., et al.
(författare)
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Reply to comment: Prey perception in feeding-current feeding copepods
- 2016
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590. ; 61:4, s. 1169-1171
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Tidskriftsartikel (refereegranskat)abstract
- We reply to the comments of Paffenhofer and Jiang (2016) who argues that remote chemical prey perception is necessary for feeding-current feeding copepods to fulfill their nutritional requirements in a dilute ocean, that remote chemical prey detection may only be observed at very low prey concentrations, and that chemical prey perception is feasible if prey cells release dissolved organic material in short-lasting but intense bursts. We demonstrate that mechanoreception at a very short range is sufficient to sustain a living, even in a dilute ocean. Further, if chemoreception requires that prey cells have short intense leakage burst, only a very small fraction of prey cells would be available to the copepod at any instance in time and, thus would be inefficient at low prey concentration. Finally, we report a few new observations of prey capture in two species of copepods, Temora longicornis and Centropages hamatus, offered a 45-mu m sized dinoflagellate at very low concentration. The observed short prey detection distances, up to a few prey cell radii, are consistent with mechanoreception and we argue briefly that near-field mechanoreception is the most likely and common prey perception mechanism in calanoid copepods.
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| 27. |
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| 28. |
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| 29. |
- 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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| 30. |
- Leandro, S. M., et al.
(författare)
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Growth and development of nauplii and copepodites of the estuarine copepod Acartia tonsa from southern Europe (Ria de Aveiro, Portugal) under saturating food conditions
- 2006
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 150:1, s. 121-129
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Tidskriftsartikel (refereegranskat)abstract
- A temperature-dependent growth model is presented for nauplii and copepodites of the estuarine calanoid copepod Acartia tonsa from southern Europe (Portugal). Development was followed from egg to adult in the laboratory at four temperatures (10, 15, 18 and 22 degrees C) and under saturating food conditions (> 1,000 mu g C l(-1)). Development times versus incubation temperature were fitted to a Belehradek's function, showing that development times decreased with increasing incubation temperature: at 10 degrees C, A. tonsa need 40.3 days to reach adult stage, decreasing to 8.9 days when reared at 22 degrees C. ANCOVA (homogeneity of slopes) showed that temperature (P < 0.001) and growth phase (P < 0.01) had a significant effect on the growth rate. Over the range of temperatures tested in this study, highest weight-specific growth rates were found during naupliar development (NI-NVI) and varied from 0.185 day(-1) (10 degrees C) to 0.880 day(-1) (22 degrees C) with a Q (10) equal to 3.66. During copepodite growth (CI-CV), the weight-specific growth rates ranged from 0.125 day(-1) (10 degrees C) to 0.488 day(-1) (22 degrees C) with a Q (10) equal to 3.12. The weight-specific growth rates (g) followed temperature (T) by a linear relationship and described as ln g=-2.962+0.130 T (r(2)=0.99, P < 0.001) for naupliar stages and ln g=-3.134+0.114T (r(2)=0.97, P < 0.001) for copepodite stages. By comparing in situ growth rates (juvenile growth and fecundity) for A. tonsa taken from the literature with the temperature-dependent growth model defined here we suggest that the adult females of A. tonsa are more frequently food limited than juveniles.
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| 31. |
- Leandro, S. M., et al.
(författare)
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Spatial and temporal scales of environmental forcing of Acartia populations (Copepoda: Calanoida) in the Canal de Mira (Ria de Aveiro, Portugal)
- 2014
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Ingår i: Ices Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 71:3, s. 585-596
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Tidskriftsartikel (refereegranskat)abstract
- Zooplankton and hydrological data were collected from August 2000 and June 2002 at six stations distributed throughout Canal de Mira (Ria de Aveiro, Portugal). The abundance of Acartia clausi and Acartia tonsa adults and juveniles of Acartia spp. for each station and month were combined in a three-way data matrix, which was decomposed into three two-way matrices corresponding to different modes: biological, time, and space. Cluster analysis applied on the space mode revealed the existence of three different zones as a consequence of zooplankton composition. At each mode, principal component analysis showed strong seasonal variations in zones 1 and 2. A different spatial pattern was found between the periods November 2000April 2001 and November 2001April 2002, with the displacement of the highest abundance levels from the middle estuary to near the mouth. The congeneric populations were segregated in space: the A. clausi population was restricted to downstream stations (zone 1), whereas the A. tonsa population dominated the middle estuary. Significant correlations between hydrological parameters and copepod abundance were found to differ from zone to zone. The statistical methodology was a valuable tool to (i) discriminate spatial and seasonal distribution patterns, (ii) define estuarine sections based on the faunistic composition, and (iii) evaluate delayed effects of phytoplankton.
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| 32. |
- Leandro, S. M., et al.
(författare)
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Temperature-dependent development and somatic growth in two allopatric populations of Acartia clausi (Copepoda : Calanoida)
- 2006
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Ingår i: Marine Ecology-Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 322, s. 189-197
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Tidskriftsartikel (refereegranskat)abstract
- This study compares the effect of temperature on the post-embryonic development time and weight-specific growth rate in 2 populations of Acartia clausi from different biogeographic areas (northern and southern Europe). Development was followed from nauplius 1 to adult at 3 temperatures (10, 15 and 18 degrees C) at saturating food conditions. The relationship between development time and temperature was established by fitting Belehradek's function. The northern population had a shorter generation time at all temperatures. At 10 degrees C, the development time was estimated to be 33.9 and 36.4 d decreasing to 16.3 and 17.4 d at 18 degrees C for the northern and southern populations, respectively. Prosome length decreased with temperature, and the southern population had longer individuals at all temperatures. ANCOVA revealed a significant (p < 0.001) positive effect of temperature on the growth rates, and nauplii grew faster than copepodites (except at 18 degrees C in the southern population and 20 degrees C in the northern population). Significant differences between populations were noted during larval growth, with nauplii from the north growing faster at high temperatures (18 degrees C). The results indicate that the 2 A. clausi allopatric populations subjected to different temperature regimes have different temperature responses, in particular at high temperatures.
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| 33. |
- Maar, M., et al.
(författare)
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Trophodynamic function of copepods, appendicularians and protozooplankton in the late summer zooplankton community in the Skagerrak
- 2004
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 144:5, s. 917-933
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Tidskriftsartikel (refereegranskat)abstract
- The study was carried out in the Skagerrak during late summer when population development in the pelagic cycle culminated in the yearly maximum in zooplankton biomass. The cyclonic circulation of surface water masses created the characteristic dome-shaped pycnocline across the Skagerrak. The large dinoflagellate Ceratium furca dominated the phytoplankton biomass. Ciliates and heterotrophic dinoflagellates were the major grazers and, potentially, consumed 43-166% of daily primary production. The grazing impact of copepods was estimated from specific egg production rates and grazing experiments. The degree of herbivory differed between species (14-85%), but coprophagy (e.g. feeding on fecal pellets) and ingestion of microzooplankton were also important. The appendicularian Oikopleura dioica was present in lower numbers than copepods, but cleared a large volume of water. The grazing impact of copepods and O. dioica was estimated to 57+/-24% and 12+/-12% of daily primary production, respectively. Sedimentation of organic material (30 m) varied between 169 and 708 mg C m(-2) day(-1), and the contribution from the mesozooplankton (copepod fecal pellets and mucus houses with attached phytodetritus of O. dioica) was 5-33% of this sedimentation. Recycling of fecal pellets and mucus houses in the euphotic zone was 59% and 36%, respectively. However, there was a high respiration of organic material by microorganisms in the mid-water column, and 34% of the sedimenting material actually reached the benthic community in the deep, central part of the Skagerrak.
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| 34. |
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| 35. |
- Magnusson, Kerstin, 1957, et al.
(författare)
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Bioaccumulation of C-14-PCB 101 and C-14-PBDE 99 in the marine planktonic copepod Calanus finmarchicus under different food regimes
- 2007
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136. ; 63:1, s. 67-81
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Tidskriftsartikel (refereegranskat)abstract
- Bioaccumulation factors (BAFs) were determined for C-14-PCB 101 and C-14-PBDE 99 in the pelagic copepod Calanus finmarchicus after exposure to either contaminated water or after being fed contaminated phytoplankton (the dinoflagellate Prorocentrum minimum or the diatom Thalassiosira weissflogii). BAFs in algae range from 7.6 to 8.0 for PCB 101 and from 8.5 to 8.6 for PBDE 99. BAFs in copepods were significantly lower, 6.3-6.8 for PCB 101 and 7.6 for PBDE 99. For each compound, the BAFs in copepods were independent of what algal species they had consumed, even though the bioaccumulation of both compounds were higher in P. minimum than in T. weissflogii. The ratios between BAF and the K-ow for PCB 101 and PBDE 99 were similar within each of the three species, but varied between species. For copepods the ratios were 2-4, for T weissfloggii 15-22 and for P. minimum 32-40. The data strongly suggest that the two compounds bioaccumulate in a similar manner and that there is no biomagnification in the transfer between phytoplankton and herbivorous copepods. (c) 2006 Elsevier Ltd. All rights reserved.
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| 36. |
- Magnusson, Kerstin, 1957, et al.
(författare)
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The importance of uptake from food for the bioaccumulation of PCB and PBDE in the marine planktonic copepod Acartia clausi
- 2010
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Ingår i: Aquatic Toxicology. - 0166-445X. ; 98:4, s. 374-380
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Tidskriftsartikel (refereegranskat)abstract
- The accumulation of 14C-labelled PCB 31, PCB 101, PCB 153 and PBDE 99 was investigated at the two lowest trophic levels of the pelagic food web. Accumulation was measured in the small phytoplankter Thalassiosira weissflogii (Coscinodiscophyceae: Thalassiosirales) and in the neritic zooplankter Acartia clausi (Copepoda: Calanoida) exposed to the substance either only via water or through ingestion of contaminated T. weissflogii. Bioaccumulation factors (BAFs) for all four compounds were significantly higher in A. clausi feeding on contaminated phytoplankton than in animals exposed only via water. The log BAF for the PCBs increased linearly with the octanol–water partitioning coefficients (log KOW) in both the algae and the copepods, but with steeper slopes for feeding than non-feeding animals. Reported values for KOW for PBDEs vary by almost an order of magnitude and it was therefore not meaningful to calculate a log BAF − log KOW ratio for PBDE 99. It is clear that the nutritional status of the zooplankton affects the uptake of the compounds and that the bioaccumulation cannot be modelled as a passive partitioning between the organisms and the surrounding water. Small copepods are typical of coastal waters and point sources (both temporal and spatial) may be the rule for HOC releases into the sea. Thus, the pathways shown in this study are important and realistic.
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| 37. |
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| 38. |
- Møller, Lene Friis, et al.
(författare)
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Ny kammanet under luppen
- 2008
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Ingår i: Havsutsikt. ; 2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 39. |
- Olivares, Manuel, et al.
(författare)
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Non-lethal effects of the predator Meganyctiphanes norvegica and influence of seasonal photoperiod and food availability on the diel feeding behaviour of the copepod Centropages typicus
- 2020
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Ingår i: Journal of Plankton Research. - : Oxford University Press (OUP). - 0142-7873 .- 1464-3774. ; 42:6, s. 742-51
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Tidskriftsartikel (refereegranskat)abstract
- Predators can induce changes in the diel activity patterns of marine copepods. Besides vertical migration, diel feeding rhythms have been suggested as an antipredator phenotypic response. We conducted experiments to assess the non-lethal direct effects of the predator Meganyctiphanes norvegica (northern krill) on the diel feeding patterns of the calanoid copepod Centropages typicus. We also analysed the influence of seasonal photoperiod and prey availability on the intensity of copepod feeding rhythms. We did not detect any large effect of krill presence on the diel feeding behaviour of copepods, either in day-night differences or total daily ingestions. Seasonal photoperiod and prey availability, however, significantly affected the magnitude of copepod feeding cycles, with larger diel differences in shorter days and at lower prey concentrations. Therefore, the role of non-lethal direct effects of predators on the diel feeding activity of marine copepods remain debatable and might not be as relevant as in freshwater zooplankton.
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| 40. |
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| 41. |
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| 42. |
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| 43. |
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| 44. |
- Selander, Erik, 1973, et al.
(författare)
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Effects of food concentration on the behaviour of Oikopleura dioica
- 2003
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Ingår i: Marine Biology. - 0025-3162. ; 142:2, s. 263-270
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Tidskriftsartikel (refereegranskat)abstract
- Feeding behaviour of the pelagic tunicate Oikopleura dioica presented with a range of food concentrations (FC, 4-670 mug Cl-1) of the flagellate Isochrysis galbana was observed using video. Simultaneous bottle incubations provided clearance rate estimates. Tail beats per minute (TB), number of tail arrests or pauses (TA) and swimming speeds were recorded. TB decreased with increasing FC, from 521 to 355 min(-1), while TA increased from 17 to 35 min(-1). Aberrant behaviour with repeated TA was found if inlet filters were obstructed by larger particles or aquarium walls. Swimming speed was 1.0 0.4 mm s(-1), and the time spent swimming decreased with FC from 38 % to 11% of the time. Clearance rate decreased sharply with FC, from 4.3 to 0.11 ml ind(-1) h(-1), resembling a type II functional response with Michaelis-Menten parameters I-max = 113 mug C ind(-1) h(-1) and K-m = 27 mug Cl-1. Using TB, TA and a residual error term, a simple model to predict clearance rate from behavioural parameters was developed. Power functions of FC were fitted to each parameter, resulting in exponents of -0.047, -0.183 and -0.38, respectively. The error term includes passive clogging and food rejection at the mouth, and was according to the model the most important for shaping the functional response.
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| 45. |
- Selander, Erik, 1973, et al.
(författare)
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Parasitic anemone infects the invasive ctenophore Mnemiopsis leidyi in the North East Atlantic
- 2010
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Ingår i: Biological invasions. - : Springer Science and Business Media LLC. - 1387-3547 .- 1573-1464. ; 12:5, s. 1003-1009
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Tidskriftsartikel (refereegranskat)abstract
- We report of the first finding of parasitic sea anemone larvae infecting the invasive ctenophore Mnemiopsis leidyi in the North East Atlantic. Parasitic anemone larvae are common in the native habitat of Mnemiopsis, but have not previously been reported from any of the locations where Mnemiopsis has been introduced. General morphology and 18S rRNA sequences support the identification of the larvae as Edwardsiella sp. Excised anemone larvae were reared through metamorphosis and confirmed the identification of the parasite. Both Mnemiopsis and Edwardsiella larvae were monitored weekly during 2007 and 2008 and parasitic larvae were recorded from September to November both years. The highest density was observed in September 2008 when Edwardsiidae larvae reached 2.3 ind m(-3). In 2008 total density of the parasite occasionally exceeded 40% of the host density and the potential consequences for Mnemiopsis population dynamics are discussed.
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| 46. |
- Selander, Erik, 1973, et al.
(författare)
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Solid phase extraction and metabolic profiling of exudates from living copepods
- 2016
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Ingår i: Peerj. - : PeerJ. - 2167-8359. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Copepods are ubiquitous in aquatic habitats. They exude bioactive compounds that mediate mate finding or induce defensive traits in prey organisms. However, little is known about the chemical nature of the copepod exometabolome that contributes to the chemical landscape in pelagic habitats. Here we describe the development of a closed loop solid phase extraction setup that allows for extraction of exuded metabolites from live copepods. We captured exudates from male and female Temora longicornis and analyzed the content with high resolution LC-MS. Chemometric methods revealed 87 compounds that constitute a specific chemical pattern either qualitatively or quantitatively indicating copepod presence. The majority of the compounds were present in both female and male exudates, but nine compounds were mainly or exclusively present in female exudates and hence potential pheromone candidates. Copepodamide G, known to induce defensive responses in phytoplankton, was among the ten compounds of highest relative abundance in both male and female extracts. The presence of copepodamide G shows that the method can be used to capture and analyze chemical signals from living source organisms. We conclude that solid phase extraction in combination with metabolic profiling of exudates is a useful tool to develop our understanding of the chemical interplay between pelagic organisms.
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| 47. |
- Sobek, A., et al.
(författare)
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Passive partitioning of polychlorinated biphenyls between seawater and zooplankton, a study comparing observed field distributions to equilibrium sorption experiments
- 2006
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 40:21, s. 6703-6708
-
Tidskriftsartikel (refereegranskat)abstract
- From previous studies, it remains unclear whether polychlorinated biphenyls (PCBs) are biomagnified in zooplankton or if concentrations are simply governed by passive partitioning. In this study, in the Gullmar Fjord on the Swedish west coast, field-determined lipid-normalized partition coefficients (log K-lip) were compared to equilibrium partition coefficients from laboratory sorption experiments with dead and preserved zooplankton. There was no significant difference between the linear regressions of log K-lip-log K-ow (analysis of covariance [ANCOVA], p < 0.05) for field and laboratory-determined partition coefficients, supporting passive partitioning being the dominant uptake pathway for PCBs in the Gullmar Fjord zooplankton. The field-observed partition coefficients were also suggestive of passive partitioning, as all field-log K-lip-log K-ow regressions were significant (p < 0.05, r(2) = 0.74-0.95) and apparently linear. Further, there was generally no positive correlation between apparent biomagnification factors (BMF; concentration in zooplankton [pg/kgoc]/concentration in phytoplankton [pg/kgoc]) and trophic level (on the basis of delta N-15). The in-situ organic carbon (-oc)-normalized concentrations in zooplankton (> 200 mu m) were not statistically different from oc-normalized concentrations in phytoplankton (0.7-50 mu m), which supports the absence of significant biomagnification.
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| 48. |
- Takahashi, K., et al.
(författare)
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Ontogenetic change of foraging behaviour during copepodite development of Acartia clausi
- 2005
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Ingår i: Marine Ecology-Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 303, s. 213-223
-
Tidskriftsartikel (refereegranskat)abstract
- Swimming behaviour of copepodite stage Cl to adults of the planktonic copepod Acartia clausi were observed at different food levels (0, 60, 500 and 2000 cells ml(-1)) of the diatom Thalassiosira weissflogii. Concurrent measures of clearance in bottle incubations were performed for Cl and adult females. All indivuduals exhibited typical jump-sink behaviour. At low food concentrations early copepodites filtered 36 % of the time, and later stages 18 %, yet the increased suspension-feeding effort did not enhance their clearance rate. Older stages and adults did not show feeding-bouts at low food concentrations, which is interpreted as a switch to the ambush-feeding mode, whereby the copepods are assumed to be searching for potentially abundant larger and motile prey, for instance, ciliates. When offered no food, frequent and long jumps were observed in all stages except for Cl. Search volumes during ambush feeding were estimated, and the slow sinking of early stages resulted in a small search volume as compared to that in later stages. Early copepodite stages depended to a higher degree on suspension feeding, regardless of food concentration, due to their undeveloped food searching ability. High food availability is therefore crucial for the growth and survival of early copepodite stages of A. clausi. The heavier body of later stages enhanced foraging efficiency both during suspension feeding (by gravity tethering) and in ambush feeding (by faster sinking).
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| 49. |
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| 50. |
- Tiselius, Peter, 1958
(författare)
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An in situ video camera for plankton studies: design and preliminary observations
- 1998
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Ingår i: Marine Ecology-Progress Series. - 0171-8630. ; 164, s. 293-299
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Tidskriftsartikel (refereegranskat)abstract
- A design for an in situ video camera for plankton observations is presented. A light weight aluminium rig supports a video camera with an opposing stroboscope which produces dark field images of plankton >0.3 mm. In the present configuration the camera can be used down to 100 m and provides video images of 10 to 40x magnification when viewed on a 14 " (ca 35 cm) monitor. Video recordings from the field show moderate aggregations of small copepods to the subsurface fluorescence maximum and at times indications of horizontal patchiness. The large copepod Calanus finmarchicus was found to aggregate 5 m below the fluorescence maximum at night. In comparisons with a traditional WP-2 plankton net, the video camera provided similar length frequency distributions while abundance estimates from video recordings were 10 to 20% higher than net estimates. II is concluded that the presented video camera offers excellent observations of the pelagic environment at an affordable cost.
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