<p><i>Temora longicornis</i> and its prey (<i>R. salina</i>). (A) P... more <p><i>Temora longicornis</i> and its prey (<i>R. salina</i>). (A) Position of prey (circles) relative to the nauplius (the big oval) from detection of the prey (star) till the prey has disappeared from view and is captured (triangle). Time interval between dots: 0.45 ms. The change in relative position of the prey is due to the combined effect of the nauplius moving forward and the prey being pushed away; the prey does not swim significantly during the attack. (B) Velocity of prey and predator as a function of time. C, D. Temporal variation in X-position of appendages during prey capture (C) and prey handling (D).</p
<p>Regression lines are power laws fitted to the data. A) Maximum velocity (max vel). Blue ... more <p>Regression lines are power laws fitted to the data. A) Maximum velocity (max vel). Blue circles, <i>T. longicornis</i>: Log(max vel) = 0.40Log(BL) +2.119 (r<sup>2</sup> = 0.40, p<0.0001, n = 63); red circles, <i>O. davisae</i>: Log(max vel) = 0.42Log(BL) +2.178 (r<sup>2</sup> = 0.08, p = 0.005, n = 82); green circles, <i>A. tonsa</i>: Log(max vel) = 1.04Log(BL) +2.279 (r<sup>2</sup> = 0.82, p<0.0001, n = 82); blue triangles, <i>T. longicornis</i> swimming (slope = 0.08, p = 0.58, n = 36), B) Average velocity (avg vel), calculated for the entire relocation jump. Blue circles, <i>T. longicornis</i>: Log(max vel) = 0.30Log(BL) +1.334 (r<sup>2</sup> = 0.14, p = 0.01, n = 54); red circles, <i>O. davisae</i>: Log(max vel) = 1.06Log(BL) +2.116 (r<sup>2</sup> = 0.29, p<0.0001, n = 82); green circles, <i>A. tonsa</i>: Log(max vel) = 1.52Log(BL) +1.869 (r<sup>2</sup> = 0.73, p<0.0001, n = 82); blue triangles, <i>T. longicornis</i> swimming (slope = 1.01, p = 0.18, n = 36).</p
<p>Characteristics of the experimental nauplii and their repositioning jumps and swimming.&... more <p>Characteristics of the experimental nauplii and their repositioning jumps and swimming.</p
<p>Schematic drawing of the position and orientation of the nauplii and their prey (represe... more <p>Schematic drawing of the position and orientation of the nauplii and their prey (represented by small red dots) immediately prior to attack: (A) <i>Acartia tonsa</i> and <i>Rhodomonas salina</i>, (B) <i>Oithona davisae</i> and <i>Oxyrrhis marina</i>, (C) <i>Temora longicornis</i> and <i>R. salina</i> (<i>Heterocapsa triquetra</i> in #3 and #7), not in scale.</p
<p>Time series of still images with frame numbers indicated (consecutive frames are 0.45 ms... more <p>Time series of still images with frame numbers indicated (consecutive frames are 0.45 ms apart). Arrows point towards the prey. In the last image the prey has been captured.</p
<p>Species of the experimental nauplii, developmental stage and size (±SD) of the observed ... more <p>Species of the experimental nauplii, developmental stage and size (±SD) of the observed nauplii of <i>Acartia tonsa</i>, <i>Oithona davisae</i> and <i>Temora longicornis</i>, prey species used, distance of prey from the tip of nearest antennule and from setae on nearest antennule, attack (capture for <i>T. longicornis</i>), maximum and average attack velocity, handling time, thickness of the viscous boundary layer.</p
<p>Beat cycles analyzed for an individual nauplius of: A) <i>Oithona davisae</i>... more <p>Beat cycles analyzed for an individual nauplius of: A) <i>Oithona davisae</i> (body length = 0.154 mm), B) <i>Acartia tonsa</i> (body length = 0.154 mm), C) <i>Temora longicornis</i> (body length = 0.168 mm), and D) <i>T. longicornis</i> swimming (body length = 0.290 mm). Body velocity (upper panels), total distance travelled (middle panels) and the position of appendages relative to the tip of the nauplius head (lower panels), all as function of time. Positions of the tips of antennules, antennae and mandibles relative to the tip of the body are shown in blue, red and green, respectively. Grey vertical dashed lines indicate the end/beginning of a beat cycle, ibc: initial beat cycle, 1bc: first beat cycle, 2bc: second beat cycle.</p
<p><i>Oithona davisae</i> and its prey (<i>O. marina</i>). (A) Posi... more <p><i>Oithona davisae</i> and its prey (<i>O. marina</i>). (A) Position of prey (circles) relative to the nauplius (the big oval) from detection of the prey (star) till the prey has disappeared from view and is captured (triangle). Time interval between dots: 0.5 ms. The change in relative position of the prey is due to the combined effect of the nauplius moving forward and the prey being pushed away; the prey does not swim significantly during the attack. (B) Velocity of prey and predator as a function of time. C,D.Temporal variation in X-position of appendages during prey capture (capture #3) (C) and prey handling (capture #7) (D).</p
<p>Regression lines are power laws fitted to the data. A) Body length specific net distance... more <p>Regression lines are power laws fitted to the data. A) Body length specific net distance per beat cycle (DBC). Blue circles, <i>T. longicornis</i>: Log(DBC) = −0.54Log(BL) –0.27 (r<sup>2</sup> = 0.58, p<0.0001, n = 63); red circles, <i>O. davisae</i> (slope = −0.07, p = 0.29, n = 82); green circles, <i>A. tonsa</i> (slope = 0.12, p = 0.25, n = 59); blue triangles, swimming <i>T. longicornis</i> (slope = 0.01, p = 0.94, n = 36), B) Body length specific distances for the beat (DBP) and recovery (DRP) phases. Blue circles, <i>T. longicornis</i> beat phase (slope = −0.61, r<sup>2</sup> = 0.70, p<0.0001, n = 63); blue squares, <i>T. longicornis</i> recovery phase (slope = −1.77, r<sup>2</sup> = 0.54, p<0.0001, n = 63); red circles, <i>O. davisae</i> beat phase (slope = −0.16, r<sup>2</sup> = 0.03, p = 0.08, n = 81); red squares, <i>O. davisae</i> recovery phase (slope = −0.86, r<sup>2</sup> = 0.11, p = 0.001, n = 81); green circles, <i>A. tonsa</i> beat phase (slope = −0.17, r<sup>2</sup> = 0.09, p = 0.006, n = 59); green squares, <i>A. tonsa</i> recovery phase (slope = −1.14, r<sup>2</sup> = 0.70, p<0.0001, n = 58), C) Swimming <i>T. longicornis</i>, body length specific distances for the beat (DBP) and recovery phases (DRP). Blue triangles, beat phase: Log(DBP) = −0.82Log(BL) –1.56 (r<sup>2</sup> = 0.22, n = 36, p = 0.005); cyan triangles, recovery phase: Log(DRP) = −1.47Log(BL) –2.32 (r<sup>2</sup> = 0.36, n = 36, p<0.0001).</p
<p>Time series of still images with frame numbers indicated (consecutive frames are 0.5 ms ... more <p>Time series of still images with frame numbers indicated (consecutive frames are 0.5 ms apart). Arrows point towards the prey. In the last image the prey has been captured.</p
The vertical distribution of copepods, fecal pellets and the fecal pellet production of copepods ... more The vertical distribution of copepods, fecal pellets and the fecal pellet production of copepods were measured at seven stations across the Southern Indian Ocean from productive areas off South Africa to oligotrophic waters off Northern Australia during October/November 2006. We quantified export of copepod fecal pellet from surface waters and how much was retained. Furthermore, the potential impact of Oncaea spp. and harpacticoid copepods on fecal pellets degradation was evaluated and found to be regional substantial. The highest copepod abundance and fecal pellet production was found in the western nutrient-rich stations close to South Africa and the lowest at the central oligotrophic stations. The in situ copepod fecal pellet production varied between 1 and 1,000 µg C/m**3/day. At all stations, the retention of fecal pellets in the upper 400 m of the water column was more than 99% and the vertical export of fecal pellets was low (<0.02 mg/m**2/day).
<p>Time series of still images with frame numbers indicated (consecutive frames are 0.5 ms ... more <p>Time series of still images with frame numbers indicated (consecutive frames are 0.5 ms apart). Arrows point towards the prey. In the last image the prey has been captured.</p
We present a study on the protozooplankton >5µm and copepods larger than 50 µm at a series of ... more We present a study on the protozooplankton >5µm and copepods larger than 50 µm at a series of contrasting stations across the Southern Indian Ocean (SIO). Numerically, over 80% of the copepod community across the transect was less than 650 µm in size, dominated by nauplii, and smaller copepods, while 80% of the biomass (as mgC m-3) was larger than 1300 µm in body length. Predation by the carnivorous copepod Corycaeus sp. was estimated to be able to remove up to 2% d-1 of the copepods <1000 µm in size. By help of grazing models we estimated that primary producers were mainly grazed upon by ciliates and heterotrophic dinoflagellates (40-80% d-1 combined) in temperate waters but appendicularians became increasingly important in the tropical waters grazing about 40% of the biomass per day. Despite their high abundance and biomass, copepods contributed less than 20% of the grazing at most stations. Secondary production was low (carbon specific egg production <0.14 d-1) but typic...
<p><i>Temora longicornis</i> and its prey (<i>R. salina</i>). (A) P... more <p><i>Temora longicornis</i> and its prey (<i>R. salina</i>). (A) Position of prey (circles) relative to the nauplius (the big oval) from detection of the prey (star) till the prey has disappeared from view and is captured (triangle). Time interval between dots: 0.45 ms. The change in relative position of the prey is due to the combined effect of the nauplius moving forward and the prey being pushed away; the prey does not swim significantly during the attack. (B) Velocity of prey and predator as a function of time. C, D. Temporal variation in X-position of appendages during prey capture (C) and prey handling (D).</p
<p>Regression lines are power laws fitted to the data. A) Maximum velocity (max vel). Blue ... more <p>Regression lines are power laws fitted to the data. A) Maximum velocity (max vel). Blue circles, <i>T. longicornis</i>: Log(max vel) = 0.40Log(BL) +2.119 (r<sup>2</sup> = 0.40, p<0.0001, n = 63); red circles, <i>O. davisae</i>: Log(max vel) = 0.42Log(BL) +2.178 (r<sup>2</sup> = 0.08, p = 0.005, n = 82); green circles, <i>A. tonsa</i>: Log(max vel) = 1.04Log(BL) +2.279 (r<sup>2</sup> = 0.82, p<0.0001, n = 82); blue triangles, <i>T. longicornis</i> swimming (slope = 0.08, p = 0.58, n = 36), B) Average velocity (avg vel), calculated for the entire relocation jump. Blue circles, <i>T. longicornis</i>: Log(max vel) = 0.30Log(BL) +1.334 (r<sup>2</sup> = 0.14, p = 0.01, n = 54); red circles, <i>O. davisae</i>: Log(max vel) = 1.06Log(BL) +2.116 (r<sup>2</sup> = 0.29, p<0.0001, n = 82); green circles, <i>A. tonsa</i>: Log(max vel) = 1.52Log(BL) +1.869 (r<sup>2</sup> = 0.73, p<0.0001, n = 82); blue triangles, <i>T. longicornis</i> swimming (slope = 1.01, p = 0.18, n = 36).</p
<p>Characteristics of the experimental nauplii and their repositioning jumps and swimming.&... more <p>Characteristics of the experimental nauplii and their repositioning jumps and swimming.</p
<p>Schematic drawing of the position and orientation of the nauplii and their prey (represe... more <p>Schematic drawing of the position and orientation of the nauplii and their prey (represented by small red dots) immediately prior to attack: (A) <i>Acartia tonsa</i> and <i>Rhodomonas salina</i>, (B) <i>Oithona davisae</i> and <i>Oxyrrhis marina</i>, (C) <i>Temora longicornis</i> and <i>R. salina</i> (<i>Heterocapsa triquetra</i> in #3 and #7), not in scale.</p
<p>Time series of still images with frame numbers indicated (consecutive frames are 0.45 ms... more <p>Time series of still images with frame numbers indicated (consecutive frames are 0.45 ms apart). Arrows point towards the prey. In the last image the prey has been captured.</p
<p>Species of the experimental nauplii, developmental stage and size (±SD) of the observed ... more <p>Species of the experimental nauplii, developmental stage and size (±SD) of the observed nauplii of <i>Acartia tonsa</i>, <i>Oithona davisae</i> and <i>Temora longicornis</i>, prey species used, distance of prey from the tip of nearest antennule and from setae on nearest antennule, attack (capture for <i>T. longicornis</i>), maximum and average attack velocity, handling time, thickness of the viscous boundary layer.</p
<p>Beat cycles analyzed for an individual nauplius of: A) <i>Oithona davisae</i>... more <p>Beat cycles analyzed for an individual nauplius of: A) <i>Oithona davisae</i> (body length = 0.154 mm), B) <i>Acartia tonsa</i> (body length = 0.154 mm), C) <i>Temora longicornis</i> (body length = 0.168 mm), and D) <i>T. longicornis</i> swimming (body length = 0.290 mm). Body velocity (upper panels), total distance travelled (middle panels) and the position of appendages relative to the tip of the nauplius head (lower panels), all as function of time. Positions of the tips of antennules, antennae and mandibles relative to the tip of the body are shown in blue, red and green, respectively. Grey vertical dashed lines indicate the end/beginning of a beat cycle, ibc: initial beat cycle, 1bc: first beat cycle, 2bc: second beat cycle.</p
<p><i>Oithona davisae</i> and its prey (<i>O. marina</i>). (A) Posi... more <p><i>Oithona davisae</i> and its prey (<i>O. marina</i>). (A) Position of prey (circles) relative to the nauplius (the big oval) from detection of the prey (star) till the prey has disappeared from view and is captured (triangle). Time interval between dots: 0.5 ms. The change in relative position of the prey is due to the combined effect of the nauplius moving forward and the prey being pushed away; the prey does not swim significantly during the attack. (B) Velocity of prey and predator as a function of time. C,D.Temporal variation in X-position of appendages during prey capture (capture #3) (C) and prey handling (capture #7) (D).</p
<p>Regression lines are power laws fitted to the data. A) Body length specific net distance... more <p>Regression lines are power laws fitted to the data. A) Body length specific net distance per beat cycle (DBC). Blue circles, <i>T. longicornis</i>: Log(DBC) = −0.54Log(BL) –0.27 (r<sup>2</sup> = 0.58, p<0.0001, n = 63); red circles, <i>O. davisae</i> (slope = −0.07, p = 0.29, n = 82); green circles, <i>A. tonsa</i> (slope = 0.12, p = 0.25, n = 59); blue triangles, swimming <i>T. longicornis</i> (slope = 0.01, p = 0.94, n = 36), B) Body length specific distances for the beat (DBP) and recovery (DRP) phases. Blue circles, <i>T. longicornis</i> beat phase (slope = −0.61, r<sup>2</sup> = 0.70, p<0.0001, n = 63); blue squares, <i>T. longicornis</i> recovery phase (slope = −1.77, r<sup>2</sup> = 0.54, p<0.0001, n = 63); red circles, <i>O. davisae</i> beat phase (slope = −0.16, r<sup>2</sup> = 0.03, p = 0.08, n = 81); red squares, <i>O. davisae</i> recovery phase (slope = −0.86, r<sup>2</sup> = 0.11, p = 0.001, n = 81); green circles, <i>A. tonsa</i> beat phase (slope = −0.17, r<sup>2</sup> = 0.09, p = 0.006, n = 59); green squares, <i>A. tonsa</i> recovery phase (slope = −1.14, r<sup>2</sup> = 0.70, p<0.0001, n = 58), C) Swimming <i>T. longicornis</i>, body length specific distances for the beat (DBP) and recovery phases (DRP). Blue triangles, beat phase: Log(DBP) = −0.82Log(BL) –1.56 (r<sup>2</sup> = 0.22, n = 36, p = 0.005); cyan triangles, recovery phase: Log(DRP) = −1.47Log(BL) –2.32 (r<sup>2</sup> = 0.36, n = 36, p<0.0001).</p
<p>Time series of still images with frame numbers indicated (consecutive frames are 0.5 ms ... more <p>Time series of still images with frame numbers indicated (consecutive frames are 0.5 ms apart). Arrows point towards the prey. In the last image the prey has been captured.</p
The vertical distribution of copepods, fecal pellets and the fecal pellet production of copepods ... more The vertical distribution of copepods, fecal pellets and the fecal pellet production of copepods were measured at seven stations across the Southern Indian Ocean from productive areas off South Africa to oligotrophic waters off Northern Australia during October/November 2006. We quantified export of copepod fecal pellet from surface waters and how much was retained. Furthermore, the potential impact of Oncaea spp. and harpacticoid copepods on fecal pellets degradation was evaluated and found to be regional substantial. The highest copepod abundance and fecal pellet production was found in the western nutrient-rich stations close to South Africa and the lowest at the central oligotrophic stations. The in situ copepod fecal pellet production varied between 1 and 1,000 µg C/m**3/day. At all stations, the retention of fecal pellets in the upper 400 m of the water column was more than 99% and the vertical export of fecal pellets was low (<0.02 mg/m**2/day).
<p>Time series of still images with frame numbers indicated (consecutive frames are 0.5 ms ... more <p>Time series of still images with frame numbers indicated (consecutive frames are 0.5 ms apart). Arrows point towards the prey. In the last image the prey has been captured.</p
We present a study on the protozooplankton >5µm and copepods larger than 50 µm at a series of ... more We present a study on the protozooplankton >5µm and copepods larger than 50 µm at a series of contrasting stations across the Southern Indian Ocean (SIO). Numerically, over 80% of the copepod community across the transect was less than 650 µm in size, dominated by nauplii, and smaller copepods, while 80% of the biomass (as mgC m-3) was larger than 1300 µm in body length. Predation by the carnivorous copepod Corycaeus sp. was estimated to be able to remove up to 2% d-1 of the copepods <1000 µm in size. By help of grazing models we estimated that primary producers were mainly grazed upon by ciliates and heterotrophic dinoflagellates (40-80% d-1 combined) in temperate waters but appendicularians became increasingly important in the tropical waters grazing about 40% of the biomass per day. Despite their high abundance and biomass, copepods contributed less than 20% of the grazing at most stations. Secondary production was low (carbon specific egg production <0.14 d-1) but typic...
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