| 1. |
- Azour, Farivar, et al.
(författare)
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Invasion rate and population characteristics of the round goby Neogobius melanostomus: effects of density and invasion history
- 2015
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Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7782 .- 1864-7790. ; 24:1, s. 41-52
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Tidskriftsartikel (refereegranskat)abstract
- Round goby Neogobius melanostomus is currently one of the most wide-ranging invasive fish species in Europe and North America. The present study demonstrates how the distribution of round goby has expanded from 2008 to 2013 at a rate of about 30 km yr(-1) along the Danish coastline in the western Baltic Sea. Further analyses showed that fish from an established high-density round goby population were slow-growing and displayed poorer condition (weight at age and hepatosomatic index) compared to fish sampled from recently invaded locations (i.e. at the forefront of the distribution range). The established population revealed a broad age distribution and a 1:1 gender ratio, while fish from a recently invaded site were primarily of intermediate ages with a male-biased gender ratio. Otolith analyses suggested that the oldest individuals from the recently invaded area experienced superior growth conditions only in the most recent years, suggesting immigration into the area as adults. Our results suggest that intraspecific competition for food may cause continued dispersal of the species and that population demographics likely relate to invasion history.
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| 2. |
- Bergström, Ann-Kristin, et al.
(författare)
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Phytoplankton responses to nitrogen and phosphorus enrichment in unproductive Swedish lakes along a gradient of atmospheric nitrogen deposition
- 2008
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Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7782 .- 1864-7790. ; 4, s. 55-64
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Tidskriftsartikel (refereegranskat)abstract
- Lake sampling and in situ nutrient enrichment enclosure experiments with nitrogen (N) and phosphorus (P) were conducted in unproductive Swedish lakes along a gradient of increasing atmospheric N-deposition. The regional and seasonal patterns of nutrient limitation of phytoplankton were clearly related to the amounts of N-deposition and N-inputs the lakes received. In areas of low N-deposition in northern Sweden, N-limitation of phytoplankton was evident throughout the summer season due to high catchment N-retention and very low dissolved inorganic N (DIN) inputs during the early summer. High N-deposition in the south was accompanied by high lake DIN-concentrations during the early summer and subsequent P-limitation of phytoplankton. However, P-limitation did not persist over the summer and, as a consequence of a declining DIN-pool, the lakes switched to dual- and co-limitation by N and P, and then to N-limitation. Generally, the lakes were N-limited rather than P-limited during the summer. We conclude that N-limitation is probably a natural state of the unproductive lakes studied, but P-limitation of variable intensity and duration has been induced by elevated atmospheric N-deposition.
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| 3. |
- Clark, M. S., et al.
(författare)
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Delayed arm regeneration in the Antarctic brittle star Ophionotus victoriae
- 2007
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Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7790 .- 1864-7782. ; 1:1, s. 45-53
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Tidskriftsartikel (refereegranskat)abstract
- We describe the levels of natural arm damage in the Antarctic brittle star Ophionotus victoriae and the rate of arm regeneration over the period of 1 yr, as measured in our aquarium facilities at Rothera Point, West Antarctic Peninsula. The natural incidence of arm damage in O. victoriae is high (97 % of individuals examined). The rate of regeneration was 0.44 mm wk(-1), which is slow, but within the range of data from temperate brittle stars and also in line with data from the literature showing a general trend of decreasing arm regeneration rate with temperature. The Q(10) for arm regeneration rate of 2.6 across brittle stars is within the expected biological range. However, O. victoriae arm regeneration experiences a lag phase of up to 5 mo before reproducible amounts of new tissue are produced. Such a long lag phase has not been documented for any other brittle star species and produces a range of Q(10) values from 3.6 (when compared to the slowest documented lag phase for a temperate brittle star) to exceptionally high Q(10) values of 14.9 and 15.4 (when either fastest or average regeneration times are considered for temperate brittle stars and this Antarctic species). This indicates that the initial process of arm regeneration in O. victoriae is either different to that of other brittle stars or it is dependent on factors other than the effects of temperature on enzyme-mediated biochemical reactions, such as gonadal cycles and seasonality.
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| 4. |
- Ejdung, Gunilla, et al.
(författare)
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Predation by crustaceans on native and non-native Baltic clams
- 2009
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Ingår i: Aquatic biology. - : Inter-Research Science Center. - 1864-7790 .- 1864-7782. ; 6, s. 15-24
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Tidskriftsartikel (refereegranskat)abstract
- We studied the effect of crustacean predators on native/non-native Macoma balthica bivalves in aquarium experiments. North Sea M balthica (NS Macoma) were recently observed in the southern Baltic Sea. They differ genetically and in terms of morphology, behaviour and evolutionary history from Baltic Sea M balthica (BS Macoma), and this may affect predation pressure and community structure. We hypothesised that predators consume more of the prey they co-exist with. NS Macoma and BS Macoma were exposed to crustacean predators common in the North Sea (Carcinus maenas and Crangon crangon) and in the Baltic Sea (C. crangon and Saduria entomon). Contrary to our hypotheses, the North Sea predators ate more BS Macoma, and S. entomon ate more NS Macoma. The crush-limited C. maenas preyed more on globular BS Macoma, whereas S. entomon, which do not crush but pry open the bivalve shell, ate more NS Macoma, which have a lighter (thus probably thinner) shell than BS Macoma. When NS and BS Macoma were offered together, BS Crangon ate more NS Macoma. We also studied BS Crangon consumption of M. balthica to assess whether sizes offered fall within the size spectrum that C. crangon can eat. Small (20 to 40 mm long), medium (40 to 50 mm) and large (50 to 60 mm) C. crangon especially ate small M. balthica. Differences in shape, size and meat/shell weight ratio between the BS and NS Macoma partly explained the differences in the susceptibility to predation by native and non-native predators.
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| 5. |
- Ejdung, Gunilla, et al.
(författare)
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Uptake of diatoms in Baltic Sea macrozoobenthos during short-term exposure to severe and moderate hypoxia.
- 2008
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Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7790 .- 1864-7782. ; 3:1, s. 89-99
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Tidskriftsartikel (refereegranskat)abstract
- he effect of severe and moderate hypoxia on food uptake of benthic macrofauna was studied in the laboratory. The hypothesis was that low oxygen concentrations negatively affect feeding at oxygen levels that have little effect on the studied animals' survival. The bivalve Macoma balthica, the priapulid Halicryptus spinulosus, the amphipods Monoporeia affinis (subadult & juvenile) and Pontoporeia femorata (subadult) were offered the C-14-labelled diatom Skeletonema costatum in 0.8 to 10.6 mg O-2 l(-1). Feeding was measured as radioactivity uptake. Subadult amphipods were studied one species at a time (single) or together (mixed). Feeding changed in all amphipods at the lowest oxygen concentrations, but no effect was found for M. balthica and H. spinulosus. At the lowest concentration (0.8 mg O-2 l(-1)) feeding by subadult M affinis (single) was only 17% of the full oxygen saturation (10.6 mg O-2 l(-1)), and, at 1.6 mg O-2 l(-1), 14% of the feeding at 8.9 mg O-2 l(-1). Juvenile M affinis consumed more labelled algae at 3 Mg O-2 l(-1) than at higher oxygen concentrations. M balthica feeding was not affected. Little radioactivity uptake was registered for H. spinulosus at any oxygen concentration, showing that H. spinulosus is not a surface deposit feeder. The amphipods were the most sensitive to week-long oxygen deficiency. Survival decreased significantly in the lowest oxygen concentrations (0.8; 1.6 mg O-2 l(-1)). Of the subadult M. affinis 15 and 65%, respectively, survived, compared with 0 and 58% for P. femorata. Juvenile M. affinis mortality was high in all oxygen concentrations, whereas most M balthica and H. spinulosus survived.
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| 6. |
- Eriksson Wiklund, Ann-Kristin, et al.
(författare)
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Behavioural and physiological responses to pharmaceutical exposure in macroalgae and grazers from a Baltic Sea littoral community
- 2011
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Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7782 .- 1864-7790. ; 14:1, s. 29-39
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Tidskriftsartikel (refereegranskat)abstract
- Gammarus spp. and Fucus vesiculosus from the Baltic Sea littoral community were exposed to 3 concentrations of the pharmaceuticals ibuprofen and propranolol. Both physiological and behavioural parameters were measured to examine potential effects in the organisms. For Gammarus spp., respiration, feeding rate and activity with and without predator cues were measured, and gross production to respiration ratio (GP/R) and chlorophyll fluorescence were measured for F. vesiculosus. The results showed that propranolol decreased the activity related to movement, and Gammarus spp. could not compensate for the reduced movement when subjected to predator cues. The feeding rates of Gammarus spp. exposed to propranolol were more than 2 times higher at all concentrations compared to the control. Ibuprofen did not significantly affect any of the measured parameters of Gammarus spp. The GP/R was lower in algae exposed to propranolol. The effects of propranolol on both behaviour and physiology of Gammarus spp., in combination with the stress responses in the algae, might cause unexpected indirect and cascade effects which eventually could have implications at both community and ecosystem scales.
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| 7. |
- Hu, Marian, 1981
(författare)
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Metabolic energy demand and food utilization of the hydrothermal vent crab Xenograpsus testudinatus (Crustacea: Brachyura)
- 2012
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Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7782 .- 1864-7790. ; 15:1, s. 11-25
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Tidskriftsartikel (refereegranskat)abstract
- The hydrothermal vent crab Xenograpsus testudinatus (Crustacea: Brachyura) is endemic near Kueishan Island, Taiwan, where it lives in shallow waters close to the hydrothermal vents located in this area. X. testudinatus is adapted to a sulfur-rich and thus potentially toxic environment. It has established a specialized feeding strategy focusing on dead zooplankton organisms killed by the toxic discharges from the vents. During slack water, when there is little or no current, the crabs leave their crevices to feed on this ‘marine snow’. In the present study, we investigated the physiological aspects of nutritional adaptations of X. testudinatus. The crabs showed high digestive capacities of major digestive enzymes and particularly high activities for proteolytic enzymes. This feature can be regarded as an adaptation to irregular food availability. Furthermore, enzymes were stable at elevated temperatures, in a wide pH range, and in the presence of inorganic inhibitors like Cu2+, Fe2+, or Co2+. These enzyme properties can be considered essential to functioning in a vent habitat over long exposure times. Moreover, X. testudinatus is able to store significant amounts of lipid (50 to 60% of dry mass in the midgut gland), which may help to overcome periods of food scarcity. Fatty acid profiles revealed high amounts of saturated and monounsaturated components (mainly 16:0, 16:1(n-7), 18:1(n-9), and 18:1(n-7)). These findings reflect physiological adaptations and energetic strategies that enable this crab to exist in this extreme hydrothermal vent habitat. KEY WORDS: Hydrothermal vents · Crustacea · Xenograpsus testudinatus · Digestive enzymes · Fatty acids · Toxic environment · Heavy metals
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| 8. |
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| 9. |
- Jacoby, Charles A., et al.
(författare)
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Vertical distribution, behavior, chemical composition and metabolism of Stauroteuthis syrtensis (Octopoda : Cirrata) in the northwest Atlantic
- 2009
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Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7782 .- 1864-7790. ; 5:1, s. 13-22
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Tidskriftsartikel (refereegranskat)abstract
- The cirrate octopod Stauroteuthis syrtensis is a mesopelagic species commonly collected in the North Atlantic. Individuals were observed at depths > 600 m and typically within 100 m of the bottom in three similar to 900 m deep canyons indenting the southern edge of Georges Bank. When first sighted, most octopods were floating passively with their webbed arms gathered into a small ball. When disturbed, they expanded their webs to form a 'balloon' shape, swam slowly by Sculling their fins, pulsed their webs like medusae and, in some cases, streamlined their arms and webs and moved away smoothly by rapidly sculling their fins. The bodies of 9 octopods comprised 92 to 95 % water, with tissue containing 9 to 22 % carbon (C) and 2 to 4 % nitrogen (N). These values were similar to those reported for medusae and ctenophores. Oxygen (O(2)) consumption rates of 4.6 to 25.8 mu mol 02 g(-1) C h(-1) were within ranges reported for medusae, ctenophores, and deep-water cephalopods. The stomachs of S. syrtensis, dissected immediately after capture, contained only the calanoid copepod Calan us finmarchicus. Calculations indicated that S. syrtensis need 1.3 to 30.1 ind. d(-1) of C. finmarchicus to meet their measured metabolic demand. Excretion rates (0.3 to 12.4 mu g NH(4)(+) g(-1) C h(-1) and 0.06 to 4.83 mu g PO(4)(3-) g(-1) C h(-1)) were at least an order of magnitude lower than rates reported for other octopods or gelatinous zooplankters. O:N ratios (11 to 366) suggested that S. syrtensis catabolized lipids, which may be supplied by C. finmarchicus. Vertical distribution, relatively torpid behavior and low metabolic rates characterized S. syrtensis as a benthopelagic and relatively passive predator on copepods.
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| 10. |
- Maire, O., et al.
(författare)
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Quantification of sediment reworking rates in bioturbation research: a review
- 2008
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Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7790 .- 1864-7782. ; 2:3, s. 219-238
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Tidskriftsartikel (refereegranskat)abstract
- This review lists and discusses the different methods currently available to assess sediment reworking by benthic infauna. Direct methods are used to estimate the amount of sediment transported by infauna at the sediment-water interface during a given period of time. Particle-tracer methods are used to quantify the vertical distribution of particle tracers within the sediment column. Tracers are classified based on their mode of introduction at the sediment-water interface (i.e. whether they occur naturally or are deliberately introduced at the onset of the experiment). The main characteristics of each method, including modelling aspects, are presented, and their respective advantages and drawbacks are outlined with a particular emphasis on their accuracy, spatial (i.e. both horizontal and vertical) and temporal resolutions. Direct and particle-tracer methods assess different components of sediment reworking. Selection of the most appropriate approach depends on the specific question(s) to be answered, as well as other factors, including the behaviour of the organisms studied, the spatial and temporal scales considered, and whether the experiments are carried out in situ or under controlled laboratory conditions.
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