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Song Sun - One of the best experts on this subject based on the ideXlab platform.
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Grazing and metabolism of Euphausia pacifica in the Yellow Sea.
PLOS ONE, 2015Co-Authors: Zhencheng Tao, Song SunAbstract:Grazing and metabolism of Euphausia pacifica in the Yellow Sea were studied from September 2006 to August 2007. Euphausia pacifica is a selective-feeding omnivore and grazing rates among different months were monitored using a Coulter Counter and batch culture feeding experiments. Euphausia pacifica mainly grazed microzooplankton in August and September, which resulted in an increase in chlorophyll a concentration. Oxygen consumption rate of E. pacifica was 38.7–42.5 μmol O2 g-1 DW h-1 in March, which was four times higher than the oxygen consumption rates in September and December. The vigorous metabolism of E. pacifica in March consumed 3.1% of body carbon daily, which is likely related to its high reproduction and grazing rate. Respiration and metabolism of E. pacifica in September and December were similar and were lower. O:N ratio of E. pacifica was the highest (17.3–23.8) in March when spawning activity occurred and when food was abundant. The energetic source of E. pacifica during September and December was mostly protein from eating a carnivorous diet, including such items as microzooplankton. Euphausia pacifica was found in cold water at the bottom of the Yellow Sea in summer and autumn and maintained a low consumption status. O:N ratios of E. pacifica in March, September, and December were negatively correlated with SSTs and no significant correlation was found between O:N ratios and chlorophyll a concentration. Seawater temperature is clearly the most important parameter influencing the metabolism of E. pacifica.
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The distribution and demography of Euphausia superba in Prydz Bay during the austral summer 2002
ADVANCES IN POLAR SCIENCE, 2013Co-Authors: Yongqin Liu, Song Sun, Yong-shan Zhang, Huilian LiuAbstract:This study documents the horizontal distribution and demography of Antarctic krill (Euphausia superba Dana), collectedusing trawls, from the Prydz Bay region during January 2002. Euphausia superba (E. superba) was distributed primarilysouth of 64°S. The average density and biomass were estimated as 68.85 ind·(1 000 m -3 ) and 24.16 g wet weight·(1 000 m -3 ), respectively.Highest values were located in the open sea (depth > 3 000 m). Body length of E. superba ranged from 30 to 55 mm(N=1 758), with a mean length of 38.45±3.68 mm (SD). The overall sex ratio was approximately 1∶1, 47.6% females (41.9%sub-adults and 5.7% adults), 46.6% males (42.7% sub-adults and 3.9% adults), while 5.8% were juveniles. The population structureof E. superba exhibited geographical variation. At stations in the western part of the survey area populations had a high proportionof juveniles, a lower sexual maturity stage for males and small body size, while the opposite was found at stations in theeastern part. A latitudinal difference was found at stations along 70.5°E and 73°E transects: body length was small and the sex ratiowas high in regions of high latitude, while the opposite occurred in areas of low latitude.
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spatial distribution and population structure of Euphausia pacifica in the yellow sea 2006 2007
Journal of Plankton Research, 2011Co-Authors: Song Sun, Zhencheng Tao, Huilian LiuAbstract:We studied spatial distribution patterns, population structure and egg production rates of Euphausia pacifica in the Yellow Sea from April 2006 to August 2007 during eight cruises. We investigated the distribution of the developmental stages in relation to environmental factors (temperature, salinity and chlorophyll a). We used principal components analysis and Pearson's correlation to analyze the covariation and correlation between E. pacifica abundances and environmental factors. The spatial distribution of E. pacifica was controlled primarily by seawater temperature and the adults preferentially inhabited cold water. Euphausia pacifica occurred nearly throughout the entire study area in spring and winter. When surface seawater temperature was over 20 degrees C in summer and autumn, E. pacifica was mainly located in the Yellow Sea Bottom Cold Water (YSBCW) area where the temperature below the thermocline was 8-10 degrees C. On-board incubation experiments showed that the brood size of E. pacifica was highest in spring. We conclude that E. pacifica can undergo its whole life history and maintain high abundance in the Yellow Sea. Recruitment is mainly in spring, after which it is very low. In summer and autumn, the population is mainly distributed in the YSBCW, which offers animals a refuge from warm surface waters.
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Spatial distribution and population structure of Euphausia pacifica in the Yellow Sea (2006–2007)
Journal of Plankton Research, 2010Co-Authors: Song Sun, Zhencheng Tao, Huilian LiuAbstract:We studied spatial distribution patterns, population structure and egg production rates of Euphausia pacifica in the Yellow Sea from April 2006 to August 2007 during eight cruises. We investigated the distribution of the developmental stages in relation to environmental factors (temperature, salinity and chlorophyll a). We used principal components analysis and Pearson's correlation to analyze the covariation and correlation between E. pacifica abundances and environmental factors. The spatial distribution of E. pacifica was controlled primarily by seawater temperature and the adults preferentially inhabited cold water. Euphausia pacifica occurred nearly throughout the entire study area in spring and winter. When surface seawater temperature was over 20 degrees C in summer and autumn, E. pacifica was mainly located in the Yellow Sea Bottom Cold Water (YSBCW) area where the temperature below the thermocline was 8-10 degrees C. On-board incubation experiments showed that the brood size of E. pacifica was highest in spring. We conclude that E. pacifica can undergo its whole life history and maintain high abundance in the Yellow Sea. Recruitment is mainly in spring, after which it is very low. In summer and autumn, the population is mainly distributed in the YSBCW, which offers animals a refuge from warm surface waters.
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Diel vertical distribution and migration of a euphausiid Euphausia pacifica in the Southern Yellow Sea
Deep-sea Research Part Ii-topical Studies in Oceanography, 2009Co-Authors: Huilian Liu, Song SunAbstract:Stage-specific differences in the diel vertical distribution and migration of a euphausiid, Euphausia pacifica, were studied at a single station (E2,70 m water depth) in the South Yellow Sea, by sampling with a conical closing net from five discrete strata, every 3 h, for 24 h, on 2-3 May 2001. Environmental data were collected simultaneously with the net sampling. Results showed that eggs contributed a large proportion of the numerical abundance of the Euphausia pacifica population throughout the investigation. They were mainly distributed below 20 m depth, and concentrated in the 30-50 m strata throughout the day and night. Nauplius stage I (NI) was distributed below 10 m, and seldom occurred in the upper 10 m. Nauplius stage II (NII) and Metanauplius stage (MN) extended their distribution to nearly the whole water column; however, the MN resided somewhat shallower than NIL The majority of calyptopis stages I to III (CI to CIII) and early furcilia stages I to III (FI to FIII) were restricted to the upper 30 m throughout the day. The weighted mean depth tended to increase as the stage progressed from stage FI onward. Calyptopis stages showed a weak or moderate diel vertical migration behavior, and the onset of an obvious diel vertical migration took place in FII stage. The amplitude of the diel vertical migration varied with developmental stages. Stages after FIV were often absent from samples during the investigation, but from the limited available data, DVM occurred from stages FIV-VI and female adults. However, the male adults showed a somewhat different migration behavior. In summary, an ontogenetic migration pattern is obvious from this high-frequency sampling: spawning took place at 20-50 m depth, hatched nauplii sank a little, metanauplius began moving toward the surface, and calyptopis larvae reached the uppermost layer. Furcilia larvae began DVM and deepened their daytime residence depth with age. The vertical distribution of Euphausia pacifica seemed to relate to temperature and chlorophyll a. (C) 2009 Elsevier Ltd. All rights reserved.
Huilian Liu - One of the best experts on this subject based on the ideXlab platform.
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The distribution and demography of Euphausia superba in Prydz Bay during the austral summer 2002
ADVANCES IN POLAR SCIENCE, 2013Co-Authors: Yongqin Liu, Song Sun, Yong-shan Zhang, Huilian LiuAbstract:This study documents the horizontal distribution and demography of Antarctic krill (Euphausia superba Dana), collectedusing trawls, from the Prydz Bay region during January 2002. Euphausia superba (E. superba) was distributed primarilysouth of 64°S. The average density and biomass were estimated as 68.85 ind·(1 000 m -3 ) and 24.16 g wet weight·(1 000 m -3 ), respectively.Highest values were located in the open sea (depth > 3 000 m). Body length of E. superba ranged from 30 to 55 mm(N=1 758), with a mean length of 38.45±3.68 mm (SD). The overall sex ratio was approximately 1∶1, 47.6% females (41.9%sub-adults and 5.7% adults), 46.6% males (42.7% sub-adults and 3.9% adults), while 5.8% were juveniles. The population structureof E. superba exhibited geographical variation. At stations in the western part of the survey area populations had a high proportionof juveniles, a lower sexual maturity stage for males and small body size, while the opposite was found at stations in theeastern part. A latitudinal difference was found at stations along 70.5°E and 73°E transects: body length was small and the sex ratiowas high in regions of high latitude, while the opposite occurred in areas of low latitude.
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spatial distribution and population structure of Euphausia pacifica in the yellow sea 2006 2007
Journal of Plankton Research, 2011Co-Authors: Song Sun, Zhencheng Tao, Huilian LiuAbstract:We studied spatial distribution patterns, population structure and egg production rates of Euphausia pacifica in the Yellow Sea from April 2006 to August 2007 during eight cruises. We investigated the distribution of the developmental stages in relation to environmental factors (temperature, salinity and chlorophyll a). We used principal components analysis and Pearson's correlation to analyze the covariation and correlation between E. pacifica abundances and environmental factors. The spatial distribution of E. pacifica was controlled primarily by seawater temperature and the adults preferentially inhabited cold water. Euphausia pacifica occurred nearly throughout the entire study area in spring and winter. When surface seawater temperature was over 20 degrees C in summer and autumn, E. pacifica was mainly located in the Yellow Sea Bottom Cold Water (YSBCW) area where the temperature below the thermocline was 8-10 degrees C. On-board incubation experiments showed that the brood size of E. pacifica was highest in spring. We conclude that E. pacifica can undergo its whole life history and maintain high abundance in the Yellow Sea. Recruitment is mainly in spring, after which it is very low. In summer and autumn, the population is mainly distributed in the YSBCW, which offers animals a refuge from warm surface waters.
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Spatial distribution and population structure of Euphausia pacifica in the Yellow Sea (2006–2007)
Journal of Plankton Research, 2010Co-Authors: Song Sun, Zhencheng Tao, Huilian LiuAbstract:We studied spatial distribution patterns, population structure and egg production rates of Euphausia pacifica in the Yellow Sea from April 2006 to August 2007 during eight cruises. We investigated the distribution of the developmental stages in relation to environmental factors (temperature, salinity and chlorophyll a). We used principal components analysis and Pearson's correlation to analyze the covariation and correlation between E. pacifica abundances and environmental factors. The spatial distribution of E. pacifica was controlled primarily by seawater temperature and the adults preferentially inhabited cold water. Euphausia pacifica occurred nearly throughout the entire study area in spring and winter. When surface seawater temperature was over 20 degrees C in summer and autumn, E. pacifica was mainly located in the Yellow Sea Bottom Cold Water (YSBCW) area where the temperature below the thermocline was 8-10 degrees C. On-board incubation experiments showed that the brood size of E. pacifica was highest in spring. We conclude that E. pacifica can undergo its whole life history and maintain high abundance in the Yellow Sea. Recruitment is mainly in spring, after which it is very low. In summer and autumn, the population is mainly distributed in the YSBCW, which offers animals a refuge from warm surface waters.
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Diel vertical distribution and migration of a euphausiid Euphausia pacifica in the Southern Yellow Sea
Deep-sea Research Part Ii-topical Studies in Oceanography, 2009Co-Authors: Huilian Liu, Song SunAbstract:Stage-specific differences in the diel vertical distribution and migration of a euphausiid, Euphausia pacifica, were studied at a single station (E2,70 m water depth) in the South Yellow Sea, by sampling with a conical closing net from five discrete strata, every 3 h, for 24 h, on 2-3 May 2001. Environmental data were collected simultaneously with the net sampling. Results showed that eggs contributed a large proportion of the numerical abundance of the Euphausia pacifica population throughout the investigation. They were mainly distributed below 20 m depth, and concentrated in the 30-50 m strata throughout the day and night. Nauplius stage I (NI) was distributed below 10 m, and seldom occurred in the upper 10 m. Nauplius stage II (NII) and Metanauplius stage (MN) extended their distribution to nearly the whole water column; however, the MN resided somewhat shallower than NIL The majority of calyptopis stages I to III (CI to CIII) and early furcilia stages I to III (FI to FIII) were restricted to the upper 30 m throughout the day. The weighted mean depth tended to increase as the stage progressed from stage FI onward. Calyptopis stages showed a weak or moderate diel vertical migration behavior, and the onset of an obvious diel vertical migration took place in FII stage. The amplitude of the diel vertical migration varied with developmental stages. Stages after FIV were often absent from samples during the investigation, but from the limited available data, DVM occurred from stages FIV-VI and female adults. However, the male adults showed a somewhat different migration behavior. In summary, an ontogenetic migration pattern is obvious from this high-frequency sampling: spawning took place at 20-50 m depth, hatched nauplii sank a little, metanauplius began moving toward the surface, and calyptopis larvae reached the uppermost layer. Furcilia larvae began DVM and deepened their daytime residence depth with age. The vertical distribution of Euphausia pacifica seemed to relate to temperature and chlorophyll a. (C) 2009 Elsevier Ltd. All rights reserved.
Zhencheng Tao - One of the best experts on this subject based on the ideXlab platform.
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Grazing and metabolism of Euphausia pacifica in the Yellow Sea.
PLOS ONE, 2015Co-Authors: Zhencheng Tao, Song SunAbstract:Grazing and metabolism of Euphausia pacifica in the Yellow Sea were studied from September 2006 to August 2007. Euphausia pacifica is a selective-feeding omnivore and grazing rates among different months were monitored using a Coulter Counter and batch culture feeding experiments. Euphausia pacifica mainly grazed microzooplankton in August and September, which resulted in an increase in chlorophyll a concentration. Oxygen consumption rate of E. pacifica was 38.7–42.5 μmol O2 g-1 DW h-1 in March, which was four times higher than the oxygen consumption rates in September and December. The vigorous metabolism of E. pacifica in March consumed 3.1% of body carbon daily, which is likely related to its high reproduction and grazing rate. Respiration and metabolism of E. pacifica in September and December were similar and were lower. O:N ratio of E. pacifica was the highest (17.3–23.8) in March when spawning activity occurred and when food was abundant. The energetic source of E. pacifica during September and December was mostly protein from eating a carnivorous diet, including such items as microzooplankton. Euphausia pacifica was found in cold water at the bottom of the Yellow Sea in summer and autumn and maintained a low consumption status. O:N ratios of E. pacifica in March, September, and December were negatively correlated with SSTs and no significant correlation was found between O:N ratios and chlorophyll a concentration. Seawater temperature is clearly the most important parameter influencing the metabolism of E. pacifica.
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spatial distribution and population structure of Euphausia pacifica in the yellow sea 2006 2007
Journal of Plankton Research, 2011Co-Authors: Song Sun, Zhencheng Tao, Huilian LiuAbstract:We studied spatial distribution patterns, population structure and egg production rates of Euphausia pacifica in the Yellow Sea from April 2006 to August 2007 during eight cruises. We investigated the distribution of the developmental stages in relation to environmental factors (temperature, salinity and chlorophyll a). We used principal components analysis and Pearson's correlation to analyze the covariation and correlation between E. pacifica abundances and environmental factors. The spatial distribution of E. pacifica was controlled primarily by seawater temperature and the adults preferentially inhabited cold water. Euphausia pacifica occurred nearly throughout the entire study area in spring and winter. When surface seawater temperature was over 20 degrees C in summer and autumn, E. pacifica was mainly located in the Yellow Sea Bottom Cold Water (YSBCW) area where the temperature below the thermocline was 8-10 degrees C. On-board incubation experiments showed that the brood size of E. pacifica was highest in spring. We conclude that E. pacifica can undergo its whole life history and maintain high abundance in the Yellow Sea. Recruitment is mainly in spring, after which it is very low. In summer and autumn, the population is mainly distributed in the YSBCW, which offers animals a refuge from warm surface waters.
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Spatial distribution and population structure of Euphausia pacifica in the Yellow Sea (2006–2007)
Journal of Plankton Research, 2010Co-Authors: Song Sun, Zhencheng Tao, Huilian LiuAbstract:We studied spatial distribution patterns, population structure and egg production rates of Euphausia pacifica in the Yellow Sea from April 2006 to August 2007 during eight cruises. We investigated the distribution of the developmental stages in relation to environmental factors (temperature, salinity and chlorophyll a). We used principal components analysis and Pearson's correlation to analyze the covariation and correlation between E. pacifica abundances and environmental factors. The spatial distribution of E. pacifica was controlled primarily by seawater temperature and the adults preferentially inhabited cold water. Euphausia pacifica occurred nearly throughout the entire study area in spring and winter. When surface seawater temperature was over 20 degrees C in summer and autumn, E. pacifica was mainly located in the Yellow Sea Bottom Cold Water (YSBCW) area where the temperature below the thermocline was 8-10 degrees C. On-board incubation experiments showed that the brood size of E. pacifica was highest in spring. We conclude that E. pacifica can undergo its whole life history and maintain high abundance in the Yellow Sea. Recruitment is mainly in spring, after which it is very low. In summer and autumn, the population is mainly distributed in the YSBCW, which offers animals a refuge from warm surface waters.
Sangduk Choi - One of the best experts on this subject based on the ideXlab platform.
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comparative morphology of the feeding basket of five species of Euphausia crustacea Euphausiacea in the western north pacific with some ecological considerations
Hydrobiologia, 1998Co-Authors: Sangduk ChoiAbstract:The feeding basket morphology and stomach content analyses of five Euphausia species (E. recurva, E. nana, E. pacifica, E. mutica and E. similis) were compared to elucidate their feeding ecology. The filter areas of feeding basket of E. pacifica and E. nana were proportionally larger than those of others in the size classes 13-20 mm and <13 mm, respectively, suggesting a high filtering efficiency in these species at each size class. Based on the secondary setal distance, it is suggested that there are three types of feeding basket in five Euphausia species. One is the fine mesh (<5 μm) of E. pacifica and E. nana; a second is the medium (10-20 μm) of E. recurva and E. mutica; and the third is the coarse (20-30 μm) of E. similis. The ability to feed on particles <5 μm would give both species, E. pacifica and E. nana, a great advantage over other species when number of flagellates is high. Stomach content analyses indicated a more omnivorous feeding mode in E. mutica, E. recurva and E. similis and a more herbivorous in E. pacifica and E. nana. This is in agreement with morphological studies of feeding baskets. Increments in the primary and secondary setal distances with increasing size of four Euphausia species, except E. pacifica, were evident, reflecting interspecific differences in food particle sizes utilized. In E. pacifica, however, the morphological similarity should produce intraspecific competition in diet.
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Comparative morphology of the feeding basket of five species of Euphausia (Crustacea, Euphausiacea) in the western North Pacific, with some ecological considerations
Hydrobiologia, 1998Co-Authors: Hae-lip Suh, Sangduk ChoiAbstract:The feeding basket morphology and stomach content analyses of five Euphausia species (E. recurva, E. nana, E. pacifica, E. mutica and E. similis) were compared to elucidate their feeding ecology. The filter areas of feeding basket of E. pacifica and E. nana were proportionally larger than those of others in the size classes 13-20 mm and
So Kawaguchi - One of the best experts on this subject based on the ideXlab platform.
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Light regime affects the seasonal cycle of Antarctic krill (Euphausia superba): impacts on growth, feeding, lipid metabolism, and maturity
Canadian Journal of Zoology, 2018Co-Authors: Flavia Höring, So Kawaguchi, Mathias Teschke, Lavinia Suberg, Bettina MeyerAbstract:Light regime is an important zeitgeber for Antarctic krill (Euphausia superba Dana, 1850), which seems to entrain an endogenous timing system that synchronizes its life cycle to the extreme light c...
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discovery of gregarine parasitism in some southern ocean krill Euphausiacea and the salp salpa thompsoni
Polar Biology, 2017Co-Authors: Jake R Wallis, Abigail J R Smith, So KawaguchiAbstract:The presence and role of endoparasites in pelagic macrozooplankton within the Southern Ocean are poorly understood. Accounts of such parasites are generally restricted to the Antarctic krill species Euphausia superba, with little information on other possible host species. Endoparasitic gregarines were recorded for the first time in the euphausiids Euphausia triacantha and Euphausia valentini and the salp Salpa thompsoni during the Kerguelen Axis Antarctic research cruise (February–March 2016). Gregarines found in E. triacantha and E. valentini were morphologically similar to those previously identified in Antarctic krill, E. superba. Despite overlapping distributions, the smaller euphausiid Thysanoessa macrura possessed a different gregarine endoparasite, indicating parasite–host specificity in Southern Ocean euphausiids. Most notable was the discovery of large gregarines in the stomachs of aggregate individuals of S. thompsoni. The presence of gregarines in these dominant macrozooplankton indicates that endoparasitism within the Southern Ocean is more common than previously thought. Gregarines were observed in guts of krill and salps collected between 57.9 and 63.6°S. The continual presence of gregarines in the species examined indicates that these host-parasite interactions are not isolated events with differing life stages of gregarines within the same intestinal tract of some species indicating periodic infection. The impacts of gregarine parasitism on these newly identified hosts are unclear and require further investigation to understand the spatial and temporal patterns of gregarine-host interactions.
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a circadian clock in antarctic krill an endogenous timing system governs metabolic output rhythms in the euphausid species Euphausia superba
PLOS ONE, 2011Co-Authors: M Teschke, So Kawaguchi, Sabrina Wendt, Achim Kramer, Bettina MeyerAbstract:Antarctic krill, Euphausia superba, shapes the structure of the Southern Ocean ecosystem. Its central position in the food web, the ongoing environmental changes due to climatic warming, and increasing commercial interest on this species emphasize the urgency of understanding the adaptability of krill to its environment. Krill has evolved rhythmic physiological and behavioral functions which are synchronized with the daily and seasonal cycles of the complex Southern Ocean ecosystem. The mechanisms, however, leading to these rhythms are essentially unknown. Here, we show that krill possesses an endogenous circadian clock that governs metabolic and physiological output rhythms. We found that expression of the canonical clock gene cry2 was highly rhythmic both in a light-dark cycle and in constant darkness. We detected a remarkable short circadian period, which we interpret as a special feature of the krill’s circadian clock that helps to entrain the circadian system to the extreme range of photoperiods krill is exposed to throughout the year. Furthermore, we found that important key metabolic enzymes of krill showed bimodal circadian oscillations (,9–12 h period) in transcript abundance and enzymatic activity. Oxygen consumption of krill showed ,9–12 h oscillations that correlated with the temporal activity profile of key enzymes of aerobic energy metabolism. Our results demonstrate the first report of an endogenous circadian timing system in Antarctic krill and its likely link to metabolic key processes. Krill’s circadian clock may not only be critical for synchronization to the solar day but also for the control of seasonal events. This study provides a powerful basis for the investigation into the mechanisms of temporal synchronization in this marine key species and will also lead to the first comprehensive analyses of the circadian clock of a polar marine organism through the entire photoperiodic cycle.
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The hydrodynamic disturbances of two species of krill: implications for aggregation structure.
Journal of Experimental Biology, 2011Co-Authors: Kimberly B. Catton, So Kawaguchi, Donald R. Webster, Jeannette YenAbstract:SUMMARY Krill aggregations vary in size, krill density and uniformity depending on the species of krill. These aggregations may be structured to allow individuals to sense the hydrodynamic cues of neighboring krill or to avoid the flow fields of neighboring krill, which may increase drag forces on an individual krill. To determine the strength and location of the flow disturbance generated by krill, we used infrared particle image velocimetry measurements to analyze the flow field of free-swimming solitary specimens (Euphausia superba and Euphausia pacifica) and small, coordinated groups of three to six E. superba. Euphausia pacifica individuals possessed shorter body lengths, steeper body orientations relative to horizontal, slower swimming speeds and faster pleopod beat frequencies compared with E. superba. The downward-directed flow produced by E. pacifica has a smaller maximum velocity and smaller horizontal extent of the flow pattern compared with the flow produced by E. superba, which suggests that the flow disturbance is less persistent as a potential hydrodynamic cue for E. pacifica. Time record analysis reveals that the hydrodynamic disturbance is very weak beyond two body lengths for E. pacifica, whereas the hydrodynamic disturbance is observable above background level at four body lengths for E. superba. Because the nearest neighbor separation distance of E. superba within a school is less than two body lengths, hydrodynamic disturbances are a viable cue for intraspecies communication. The orientation of the position of the nearest neighbor is not coincident with the orientation of the flow disturbance, however, which indicates that E. superba are avoiding the region of strongest flow.
