Filter-feeding Copepods Research Articles

Aggregate Feeding by the Copepods Calanus and Pseudocalanus Controls Carbon Flux Attenuation in the Arctic Shelf Sea During the Productive Period

Up to 95% of the oceanic primary production is recycled within the upper few hundred meters of the water column. Marine snow and zooplankton fecal pellets in the upper water column are often recycled at rates exceeding those measured for microbial degradation, suggesting that zooplankton might be important for flux attenuation of particulate organic carbon in the upper ocean. However, direct evidence for interactions between zooplankton and settling aggregates are still rare. We investigated the importance of zooplankton aggregate feeding for carbon flux attenuation in the upper ocean by determining aggregate ingestion rates and feeding behavior on settling aggregates of the dominant Arctic filter-feeding copepods Calanus spp. and Pseudocalanus spp.. Both genera were observed to detect and feed on settling aggregates. Using in situ zooplankton and aggregate abundances in combination with the measured aggregate feeding rates, we calculated that 60-67% of the total carbon flux attenuation at three Arctic locations could be explained by Calanus spp. and Pseudocalanus spp. aggregate feeding alone. When including microbial degradation of the settling aggregates, we could explain up to 77% of the total carbon flux attenuation. Our results suggest that by directly ingesting and fragmenting settling marine snow mesozooplankton are key organisms for flux attenuation in Arctic waters.

Evidence for resource partitioning by ontogeny and species in calanoid copepods

In marine ecosystems, copepods provide an important link between primary producers and secondary consumers. However, resource partitioning in copepods within the water column remains unknown. We investigated inter- and intraspecific differences in resource utilization and feeding migration ranges among five species of filter-feeding copepods: Calanus sinicus, Mesocalanus tenuicornis, Metridia pacifica, Neocalanus cristatus, and N. plumchrus, within the epipelagic zone (0–200 m depth) in the East Sea (Japan Sea) during autumn using stable isotope analysis. In the study region, the numerical abundances of these copepods accounted for over 87% of the total number of copepods. Trophic relationships between these copepods and the vertical profiles of three types of cell-size-fractionated organic matter (POM) including pico- (<2 μm), nano- (2–20 μm), and micro-POM (20–200 μm) indicated inter- and intraspecific differences in prey-size preference and feeding migration range. The prey-size preferences of copepods appeared to be closely related to their body size. Moreover, the feeding migration ranges of C. sinicus, M. tenuicornis, and N. cristatus were confined to the surface layer during the developmental progression of copepodid stages, whereas those of M. pacifica and N. plumchrus extended from the surface to deeper layers. Therefore, we suggest that coexistence of these copepods is determined primarily by size-dependent prey-size preference, and inter- and intraspecific differences in the patterns of feeding migration.

Death in southern Patagonian fjords: Copepod community structure and mortality in land- and marine-terminating glacier-fjord systems

Glacial retreat at high latitudes has increased significantly in recent decades associated with global warming. Along Chile's Patagonian fjords, this has promoted increases in freshwater discharge, vertical stratification, and the input of organic and inorganic particles to fjords. In addition, it has modified the water chemistry [i. e. nutrient stoichiometry] and its associated biota. This study evaluates the effect of deglaciation in high-latitude fjords (54°S) on copepod survival and how this might affect the export of particulate organic carbon to the benthos. We selected two contrasting fjord systems in terms of their geomorphology and the quality and quantity of freshwater contributions: (a) Pia Fjord, with marine-terminating glaciers, and (b) Yendegaia Fjord, with land-terminating-glaciers. Both are located along the Beagle Channel (54°S), southern Chilean Patagonia.These two fjords differed significantly in phytoplankton and copepod biomass. Whereas Pia Fjord showed high chlorophyll-a concentration (7 mg Chl-a m−3) and copepod abundance (970 ind. m−3), in Yendegaia Fjord, the biomass was very low for both autotrophs (<0.3 Chl-a m−3) and copepods (470 ind. m−3). Conversely, a greater proportion of copepod carcasses was recorded in Pia (22%) versus Yendegaia (18%), with small copepods (600–1000 µm prosome length) being less affected than large ones (>1000 µm). The presence of carcasses was better explained by the amount of suspended particulate inorganic matter in the water column than by salinity. The contribution of dead copepods to the vertical carbon flux was <3.5% of the total carbon exported down to 50 m depth, with contributions of 9.5 ± 9.9 mgC m−2 d−1 in Yendegaia and 10.8 ± 10.8 mgC m−2 d−1 in Pia. Our results suggest that heavy deglaciation processes in high-latitude fjords may reduce phytoplankton biomass, causing the copepod abundance to decrease and non-predatory mortality in filter-feeding copepods to decline.

Degradation of copepod faecal pellets in the upper layer: role of microbial community and Calanus finmarchicus

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 462:39-49 (2012) - DOI: https://doi.org/10.3354/meps09808 Degradation of copepod faecal pellets in the upper layer: role of microbial community and Calanus finmarchicus Camilla Svensen*, Christian Wexels Riser, Marit Reigstad, Lena Seuthe Faculty of Biosciences, Fisheries and Economics, University of Tromsø, 9037 Tromsø, Norway *Email: camilla.svensen@uit.no ABSTRACT: Copepod faecal pellets (FP) are considered important contributors to vertical carbon flux, but investigations comparing FP production with FP export using sediment traps conclude that vertical export is not their only fate. FP are degraded to a large extent in the upper 60 m, and even among large, fast-sinking FP, only a fraction reaches sediment traps deeper than 200 m. Retention mechanisms for copepod FP are still not well understood. In order to investigate the relative importance of the small (<180 µm) compartment of the plankton community versus larger filter-feeding copepods for degradation of large, fast-sinking FP, we incubated FP produced by Calanus finmarchicus (Gunnerus) in 180 µm-filtered water from the chlorophyll a maximum. From a series of experiments, we found that the degradation of large FP is time-dependent, as no degradation was apparent after 20 or 48 h of incubation, but after 72 h FP volume was reduced by 32%. We also found that large filter-feeding copepods may facilitate the degradation process, since FP degradation increased from 0 to 75% after 48 h of incubation in the presence of 5 C. finmarchicus. We conclude that ciliates and dinoflagellates are able to degrade large copepod FP, but that this process is too slow to explain observed retention of large FP in the upper 200 m of the water column due to fast sinking of large particles. Rather than looking for single-factor explanations for flux-regulating processes, we stress the importance of investigating combined effects in relevant time frames to understand the complexity of carbon flux regulation in natural systems. KEY WORDS: Faecal pellet · Faecal pellet retention · Microbial degradation · Faecal pellet fragmentation · Calanus finmarchicus · Carbon cycling Full text in pdf format PreviousNextCite this article as: Svensen C, Wexels Riser C, Reigstad M, Seuthe L (2012) Degradation of copepod faecal pellets in the upper layer: role of microbial community and Calanus finmarchicus. Mar Ecol Prog Ser 462:39-49. https://doi.org/10.3354/meps09808 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 462. Online publication date: August 21, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

Coupling of phytoplankton community structure to nutrients, ciliates and copepods in the Gulf of Gabès (south Ionian Sea, Tunisia)

The summer spatial distribution of the phytoplankton community in the Gulf of Gabès (Tunisia, eastern Mediterranean Sea), together with environmental factors, were studied during a preliminary study conducted in July 2005 aboard the RV ‘Hannibal’. The phytoplankton community, which showed a decrease in concentration along a coastal–open sea gradient, was dominated by Dictyochophyceae (41%) followed by Dinophyceae (25%), Bacillariophyceae (16%), Cyanobacteriae (17%) and Euglenophyceae (1%). The phytoplankton found along the coast was dominated by opportunistic species (e.g.Dictyocha fibula) associated with high nutrient availability. In the open sea, phytoplankton development seemed influenced by Atlantic hydrodynamics. In addition, the Gulf of Gabès is characterized by an oligotrophic status with a summer stratification that impacted on species composition especially in off-shore areas. The coupling of phytoplankton dynamics to nutrients, ciliates and copepods showed the potential role played by ciliates not only as predators of phytoplankton but also as prey for filter-feeding copepods accounting for the increased fisheries productivity of the Gulf of Gabès.

Motile behaviour of the bloom-forming ciliate Mesodinium rubrum

Mesodinium rubrum (Lohman) (=Myrionecta rubra Jankowsky) swims backwards in jumps of short duration interspersed by longer periods of rest. Cells attain a velocity of up to 1.2 cm s–1 during jumps and this is probably a speed record for ciliates. The ciliate carries long cirri that serve as mechanoreceptors and for orientating the cell at the initiation of jumps, while the ciliary rows on the posterior part of the cell are responsible for propulsion. The cirri are sensitive to shear so that they can orientate themselves against the current in a siphon flow (such as generated by filter-feeding copepods). Mesodinium cells do not reorientate their body axis during sinking, but they reorientate their direction during the initiation of jumps so that they always tend to move upwards. Because the cells sink between jumps they can regulate their vertical position by modulation of the frequency of jumps. The cells’ tendency to drift vertically up or down is light dependent. The jumps are so rapid that these phototrophic organisms can enhance their uptake of dissolved mineral nutrients beyond the limitation of molecular diffusion.

Does Acartia clausi (Copepoda: Calanoida) use an area-restricted search foraging strategy to find food?

The swimming behavior of Acartia clausi within small aquaria containing phytoplankton was videotaped, along with unfed controls. From these videos, aspects such as swimming speed, distance traveled, and 2D (horizontal, X, and vertical, Z) headings were then measured from over 75000 X Z positional data in order to quantify their swimming functional response. There was generally no significant difference in swimming behavior between different food levels, although there was a large difference between feeding and unfed controls. Because feeding bouts moved the copepods a short distance at a slow speed, net vertical displacement decreased as feeding-bout frequency increased. Non-feeding individuals showed longer periods of sinking, interspersed with longer-distance, high-speed jumps, which displaced them farther distances than filter-feeding copepods over the same time interval. For both fed and unfed control copepods, a 1D unbiased random walk was adequate to describe their displacement over these very short time periods (10 s). This behavior is consistent with an area-restricted search foraging strategy. The net vertical displacements predicted by combining the experimental data with a 1D random walk model suggest that A. clausi would be retained within even small ∼10 cm phytoplankton patches long enough to fill their gut. However, copepods outside of phytoplankton patches must rely on other means to find patches of food greater than ∼50 cm apart. Potentially, knowledge of a copepod's swimming functional response could enable predictions about the typical spatial and temporal patchiness of its food in situ.

Comparative abundance and distribution of major filter-feeders in the Antarctic pelagic zone

The filter-feeding plankton, herbivorous copepods, salps and euphausiids, form the basic level of metazoans in the Antarctic pelagic trophic web. This paper sets out to determine the comparative share of these taxonomic groups in the total biomass and annual production. Their most abundant representatives, four copepod species ( Calanus propinquus, Calanoides acutus, Rhincalanus gigas and Metridia gerlachei), all salps and krill Euphausia superba were studied. For the first two groups net samples from six Russian expeditions in different sectors of the Antarctic were used. In total 752 samples from 118 stations were considered. The mean fresh biomass of filter-feeding copepods in the 0–1500 m layer was 18.0 g m −2 and in the entire Antarctic 576 10 6 t. The biomass of salps in comparatively restricted rich regions exceeded 500 g m −2 and in the remaining area was 1.2±0.8 g m −2, giving a total quantity of 882 10 6 t. The krill abundance estimation was based on published data, using a map of its quantitative distribution compiled from commercial trawling made by Soviet fishing and scientific ships during 17 seasons [Parfenovich, S.S., 1980. O zakonomernostyakh razmeshcheniya i regionalnoi differentsiatsii mestoskoplenii krilya v Yuzhnom Okeane. VNIRO, Moskva, in Russian.]. Three main zones based on commercial characteristics were determined by this author: (1) zone of regular occurrence of dense concentrations; (2) zone of rare occurrence of concentrations; (3) zone of low-abundance dispersed krill. All available data on E. superba biomass in the Antarctic were grouped together according to these zones and their means were calculated. The biomass of krill was found to be 60.1±11.2, 3.3±1.3 and 0.8±0.4 g m −2 fresh mass in zones 1, 2 and 3, respectively, with a total of 272 10 6 t. All estimates are compared with the literature data and their validity is discussed. For the annual production determinations the obtained biomass characteristics were multiplied by published P/B coefficients. For the copepods its value was taken as 4.4 and for krill as 0.79. The total annual production of copepods was estimated as 2534 10 6 t and that of krill as 215 10 6 t (fresh mass). Salp production could not be evaluated, for lack of a sufficient database. In terms of fresh mass, the main share of filter-feeder biomass on the entire Antarctic scale belongs to salps, due to their local maxima; the second place belongs to copepods and krill comes in the third position. But after recalculation in terms of dry mass, copepods shift to the first place and salps to the last. The annual production of copepods significantly exceeds that of krill.

Hydrothermal venting at endeavour ridge: effect on zooplankton biomass throughout the water column

Bio-acoustical data reveal that the hydrothermal plume emanating from the main vent field near 2100 m depth on Endeavour Ridge (47°57′N, 129°06′W) affects the distribution and migration of zooplankton throughout the entire water column. Net samples taken in July of 1991 and 1992 show that the standing stock of macrozooplankton integrated over the water column was considerably higher within several kilometers of the main vent site than at locations tens of kilometers from the vent site. Community analysis reveals that there were distinct shallow (<800 m depth) and deep (>800 m depth) faunal assemblages in the vent region. Shallow fauna infiltrated the deep zooplankton acoustic scattering layers in the immediate vicinity of Endeavour Ridge, producing a mixed assemblage of animals, including large numbers of juvenile filter-feeding copepods and their predators that normally inhabit the shallow layer. In contrast, the deep acoustic scattering layers found 11 km to the southeast and 15 km to the north of the central vent field in 1991, and 50 km to the west of the central vent field in 1992, were composed of distinctly deep-sea fauna. The enhanced, vertically-integrated biomass over the vent region appears to result from vertical migration of zooplankton. A simple circulation model indicates that fauna can make the round-trip journey between the top of the plume and the upper ocean without being advected beyond the range of the detectable hydrothermal effluent.

Étude expérimentale de la nutrition d'un copépode commun ( Temora stylifera Dana). Effets de la température et de la concentration de nourriture

The ingestion rate of phytoplankton by adult Temora stylifera Dana changes with concentration of algae and with temperature. From the experimental results, two types of curves were fitted to the data. The effects of these two variables are generally considered independently in grazing models. Thus, the maximal ingestion parameter of the relationship between ingestion and phytoplankton concentration is expressed as a function of temperature. It is therefore possible to formulate simultaneously the effect of these two factors. This formulation of grazing, after normalization of units, can be easily generalized to other filter-feeding copepods.

Comparison of the Feeding Behaviour of Calanus and Pseudocalanus in two Experimentally Manipulated Enclosed Ecosystems

INTRODUCTIONImplicit in some recent models of the dynamics of planktonic systems, for example that of Steele &amp; Frost (1977) is the concept that filter-feeding copepods may be scaled by size when considering feeding in relation to the size composition of their paniculate food. For a particular organism ingestion of phytoplankton has been considered to be a function of its own weight and the size composition of the phytoplankton available to it. Such scaling has been assumed to occur both in an intra- and interspecific sense, with model development involving a ‘large’ copepod {Calanus) able to feed and grow more efficiently on ‘large’ cells (diatoms) and a ‘small’ copepod {Pseudocalanus) better adapted to feed on ‘small’ cells (flagellates). However, although the general relationship between growth and metabolic rate and body size is widely accepted (Banse, 1976; Fenchel, 1974) this relationship between dietary particle-size composition and size of organism has remained a working hypothesis with little experimental support..

Particle-Size-dependent maximum grazing rates for Temora longicornis fed natural particle assemblages

The hypothesis that lower retention efficiencies of filter-feeding copepods for small particles should result in different ingestion rate versus food concentration curves for different-sized foods was tested using Temora longicornis (Muller) fed natural phytoplankton. The copepods were fed different natural phytoplankton assemblages, which varied in their species and size distribution. Volume ingestion rates were an asymptotic function of food concentration, with maximum ingestion rates measured at food concentrations exceeding 5 to 10x 106 μm3 ml-1, which were less than those occurring in the natural waters in which the copepods and phytoplankton were collected. Maximum volume ingestion rates increased linearly by a factor of 3.5, as the diameter of the particle forming the peak in the food size distribution increased fron 5 μm (primarily microflagellates) to 30 μm (mostly large diatoms). These results suggest that natural and pollutant-induced size reductions in natural phytoplankton could markedly decrease the volume of food consumed by filter-feeding copepods.

Feeding by an omnivorous planktonic copepod aetideus divergens Bradford

Aetideus divergens Bradford is representative of a large group of marine planktonic calanoid copepods which are omnivores or mixed feeders. Because very little quantitative information is available on the feeding behavior of these copepods, laboratory feeding experiments have been carried out with adult female A. divergens presented with various sizes and concentrations of diatoms and freshly hatched nauplii of Artemia. The copepod fed most efficiently on the largest size of diatom and on Artemia nauplii, but was peculiarly inefficient at feeding on small diatoms, even when they were available at very high concentrations. In this respect, the copepod differs from filterfeeding copepods, such as Calanus pacificus Brodsky. A possible explanation of this difference depends upon Aetideus being less capable of handling very small food particles than Calanus. Aetideus divergens and its congeners usually occur at subsurface depths not far below the mixed layer and seem to be adapted for feeding on large particles, possibly large phytoplanktonic organisms and fecal pellets, which sink out of the mixed layer.