Utilization of detritus by the copepod, Acartia tonsa1

Roman, Michael R.

doi:10.4319/lo.1984.29.5.0949

Cited by 172 publications

(104 citation statements)

References 44 publications

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“…ingestion was not continuous. Our observations and those of Roman (1984) suggest the hypothesis that satiation of a copepod is a function of the amount of utilizable nitrogen or energy in its food. Acartia tonsa, feeding on Thalassiosira weissflogii at concentrations from about 150 to 900.lrgC I-', became satiated near 300 pgC 1-l (Roman 1984, his Fig.…”

Section: Discussionsupporting

confidence: 68%

“…The increased ingestion of pellets in the presence of Thalassiosira weissflogii (Table 5) is attributed to an increased capture rate as observed for beads in the presence of T. weissflogii (Table 6 ) . Detrital particles (the macrophyte Thalassia testudinum) were eaten at similar rates with or without diatoms by Copepodid Stage V and adult Acartia tonsa (Roman 1984). This similarity of rates is attributed to the size of most of the detritus particles being in the range from 8 to 12 pm Equivalent Spherical Diameter (Roman 1984).…”

Section: Discussionmentioning

confidence: 87%

“…Detrital particles (the macrophyte Thalassia testudinum) were eaten at similar rates with or without diatoms by Copepodid Stage V and adult Acartia tonsa (Roman 1984). This similarity of rates is attributed to the size of most of the detritus particles being in the range from 8 to 12 pm Equivalent Spherical Diameter (Roman 1984). Non-food particles.…”

Section: Discussionmentioning

confidence: 89%

“…Calanus helgolandicus), on the other hand, ingest large (Paffenhofer 1972). The estuarine calanoid Acartia tonsa ingests large amounts of detritus (Roman 1984), and the calanoid Undinula vulgaris subsists mainly on detritus (Gerber & Marshall 1974). Poulet (1983) summed up our present knowledge on feeding processes of zooplankton by stating 'How zooplankton make the decision to capture a fraction of their food from living resources and the remainder from the detritus food chain is unknown'.…”

Section: Introductionmentioning

confidence: 99%

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The feeding response of a marine planktonic copepod to quantity and quality of particles

Paffenhöfer¹,

Sant²

1985

Mar. Ecol. Prog. Ser.

149

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Particles of varying food quality but similar size were offered singly and in mixtures to copepodid Stage V of Eucalanus pileatus to determine the rates at which calanoid copepods ingest naturally occurring particulate matter. The sequence of ingestion rate was: living phytoplankton cells > dead phytoplankton cells > fecal pellets > polystyrene spheres. Cinematographic observations revealed that both long range and short range chemoreception contributed to these differences. Living phytoplankton cells were ingested at rates 1.2 to 3 times higher than similarly-sized non-living food particles. Non-food particles offered alone were not ingested. In mixtures, the rate at which non-food particles were ingested was a function of the feeding rate on food particles. At environmental concentrations the presence of non-food particles does not appear to reduce feeding rates on food particles.

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Section: Discussionsupporting

confidence: 68%

Section: Discussionmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

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The feeding response of a marine planktonic copepod to quantity and quality of particles

Paffenhöfer¹,

Sant²

1985

Mar. Ecol. Prog. Ser.

149

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“…Both species are common in coastal waters and a low clearance of fecal pellets may be an adaptation to optimize the intake of high quality food particles in an estuarine environment where non-living particles usually dominate the particulate matter available to copepods (Paffenhöfer & Van Sant 1985). Supporting this, Roman (1984) found that only 10% of a laboratory population of A. tonsa survived 7 d on a detritus diet and that eggs could not be reared to adults on detritus. Other copepod species such as Eucalanus pileatus, Temora stylifera, and Oithona similis may be better adapted to coprophagous feeding since they clear and ingest fecal pellets at high rates (Table 5, Paffenhöfer & Knowles 1979, Paffenhöfer & Van Sant 1985, González et al 1994a.…”

Section: Processes Governing the Clearance Of Fecal Pelletssupporting

confidence: 62%

Coprophagy and coprorhexy in the copepods Acartia tonsa and Temora longicornis: clearance rates and feeding behaviour

Poulsen¹,

Kiørboe²

2005

Mar. Ecol. Prog. Ser.

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Decades of sediment trap studies have revealed that zooplankton fecal pellets constitute a much smaller fraction of the sedimentary flux than expected from the abundance of copepods and their anticipated production rates of fecal pellets. The explanation for this is thought to be coprophagy (ingestion) of fecal pellets by copepods. We examined fecal pellet clearance rate of Acartia tonsa and Temora longicornis and feeding behaviour of A. tonsa. Pellet clearance rates in A. tonsa and T. longicornis females were similar but low on their own pellets (11 to 22 ml female -1 d -1 ). Our own data together with observations compiled from the literature revealed that copepod fecal pellet clearance rates decrease with increasing relative pellet size and that all species can be described by a common relationship. In A. tonsa, the presence of alternative phytoplankton food increased pellet clearance rate. Direct observations revealed that this was accomplished through the modulating effect of phytoplankton on the feeding behaviour. In the absence of phytoplankton, A. tonsa is nonmotile but perceives sinking fecal pellets at distance. However, only a small fraction of the pellets that came within detection distance elicited an attack. In the presence of phytoplankton food, A. tonsa switched to suspension feeding, and all fecal pellets entrained in the feeding current were encountered. Independent of the feeding mode, fecal pellets were mainly degraded by fragmentation during rejection and only a small fraction was actually ingested (5%). The main impact of A. tonsa on the vertical flux of fecal pellets is therefore through coprorhexy (fragmentation) turning fecal pellets into smaller, slower-sinking particles.

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The response of two South African east coast estuaries to altered river flow regimes

Grange

Whitfield²,

Villiers

et al. 2000

Aquatic Conserv: Mar. Freshw. Ecosyst.

101

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1. Major reductions in catchment run‐off, a result of frequent and prolonged drought conditions, together with extensive impoundment of rivers and streams, has led to concern about the possible negative effects on downstream estuaries. Preliminary studies have shown that changes in river flow and associated nutrient inputs have had a predominantly negative impact on the aquatic biota of Eastern Cape estuaries. Natural successions now have human imposed trajectories which are reducing variability and forcing both freshwater ‘deprived’ and freshwater ‘enriched’ systems into artificial cycles. 2. The Kariega and Great Fish estuaries in the Eastern Cape Province are used in a comparative manner to illustrate how differences in riverine inflow can influence the structure and functioning of selected biotic components in permanently open systems. Maximum chlorophyll a values in the freshwater deprived Kariega Estuary were 1 μg L−1, whereas maximum values in the freshwater enriched Great Fish Estuary were 22 μg L−1. Mean zooplankton biomass in the lower, middle and upper reaches of the Kariega Estuary was always below 50 mg m−3, whereas in the same reaches of the Great Fish Estuary, these values ranged from 256 to 4253 mg m−3. Similarly, mean ichthyonekton densities in the mouth region of the Kariega Estuary were 49 individuals per 100 m2 compared with 279 per 100 m2 in the Great Fish Estuary. 3. Temporal changes of riverine flow reinforce the importance of allochthonous inputs to the functioning of Eastern Cape estuaries. A comparison between a dry and wet period in the Kariega Estuary revealed mean nitrate and phosphate concentrations increasing from 5 to 101 μmol L−1 and from 1 to 5 μmol L−1, respectively. Phytoplankton stocks responded positively to freshettes in both the Kariega and Great Fish estuaries. Similarly, peaks in zooplankton biomass in the Great Fish Estuary increased rapidly in response to high food resource availability resulting from elevated river discharge. The higher ichthyoplankton and ichthyonekton densities in the Great Fish Estuary, when compared with the Kariega Estuary, were attributed to a combination of stronger olfactory cues for larval immigrants from the sea and elevated food stocks in the former system. Copyright © 2000 John Wiley & Sons, Ltd.

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Utilization of detritus by the copepod, Acartia tonsa1

Cited by 172 publications

References 44 publications

The feeding response of a marine planktonic copepod to quantity and quality of particles

The feeding response of a marine planktonic copepod to quantity and quality of particles

Coprophagy and coprorhexy in the copepods Acartia tonsa and Temora longicornis: clearance rates and feeding behaviour

The response of two South African east coast estuaries to altered river flow regimes

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