Rhizocorallium hamatum (Fischer-Ooster 1858), a Zoophycos-like trace fossil from deep-sea Cretaceous-Neogene sediments

Rhizocorallium hamatum (Fischer-Ooster 1858) is a trace fossil of the Zoophycos group, which is distinguished by its mostly horizontal, branched spreite lobes. It has so far, been ascribed mainly to Zoophycos, but the latter should be limited to forms having helical whorls, which are absent in R. hamatum. It has also been ascribed to Phycosiphon, which, however, shows J-shaped spreite lobes, while the lobes of R. hamatum are U-shaped. R. hamatum is very similar to R. commune var. irregulare, but the latter displays a distinctly wider marginal tunnel with respect to lobe width. R. hamatum occurs from the Turonian to Eocene, possibly from the Hauterivian to Oligocene, but mostly from Maastrichtian to Palaeocene, deep sea, mainly turbiditic sediments rich in marl. The tracemaker, probably a ‘worm’-like invertebrate, ingested an organic-rich mud of the background sediment and relocated it into the middle to deep tiers within the underlying turbiditic marl, mostly in form of faecal pellets packed within the spreite lobes, for further use as a food resource. This way of feeding was a response to food deficiency on the deep-sea floor.     

Utility of Geochemical Analysis of Trace Fossils: Case Studies Using Phycosiphon incertum from the Lower Jurassic Shallow-Marine (Higashinagano Formation,Southwest Japan) and Pliocene Deep-Marine Deposits (Shiramazu Formation,Central Japan)

Elemental and mineralogical analyses of Phycosiphon incertum from the Lower Jurassic Higashinagano Formation and Pliocene Shiramazu Formation revealed that the core and mantle have significantly different compositions; the Al₂O₃/SiO₂ ratio, a general proxy for phyllosilicates to tectosilicates, showed a significantly (P < 0.01) higher value in the core than in the mantle. The obtained data strongly suggest that clay minerals are certainly concentrated in the core while coarse grains (i.e., quartz, feldspar) are enriched in the mantle. This is in agreement with the commonly believed interpretation of the Phycosiphon-producer; namely, it selectively ingested and excreted the clay-sized sediment grains and sorted out coarse grains. Difference in the degree of particle selection was also recognized; the tracemaker of the Higashinagano P. incertum showed greater degree of selectivity. This may be due to the differences in optimal foraging deposit-feeding activities affected by clay mineralogy of the host sediments, or in mechanistic consequences of particle selection induced by organic matter content, or in the number of other ichnotaxa recognized from each formation.     

Non-selective surface deposit feeding by the Zoophycos producers

The feeding mechanism of Zoophycos producers demonstrates non-selection by particle size or quality. The characteristic morphology and mode of Occurrence of Zoophycos and the presence of pellets with pyroclastic grains imply that the Zoophycos producers were surface deposit-feeders. They dwelt in a burrow within the sediment and ingested the grains with nutrient detritus on the sea floor around the burrow opening. Fecal pellets containing pyroclastic grains were compared with the overlying volcanic ash layers through the analyses of grain size and mineral composition based on samples from two horizons in the Upper Pliocene of Boso Peninsula, central Japan. Judging from the comparative analyses, no significant differences were found between the ash layer and the fecal pellets. This fact strongly suggests that the Zoophycos producers appear to indiscriminately ingest particles on the sediment surface. Environments of low nutrition input such as the deep sea, non-particle size and quality selection in Zoophycos producers may be the feeding strategy for the detritus-feeding burrow-dwellers. □ Zoophycos, surface deposit-feeding, Pliocene Shiramazu Formation, Boso peninsula, Japan.     

Faecal pellets in streams: their binding, breakdown and utilization

1. Faecal pellets of Gammarus (shredders) and Simulium larvae (suspension feeders) are bound by exopolymers. Immediately after egestion, Gammarus pellets are covered by a peritrophic membrane that breaks up within hours, although pellets remain intact because of internal binding materials. 2. Although they expand soon after egestion, the faecal pellets of Gammarus and Simulium remain intact for more than 30 days. Their internal structure is altered and the main agents of this change are bacteria that have survived passage through the gut (and become bound within pellets). 3. When disrupted physically, freshly egested (1‐ to 2‐day old) Simulium faecal pellets break up into relatively large pieces whereas freshly egested Gammarus faecal pellets break apart into much smaller pieces. Disruption of 30‐day old Simulium faecal pellets results in similar sized pieces to those from freshly egested pellets, but disruption of 30‐day old Gammarus pellets produces pieces that are two orders of magnitude larger than those resulting from disruption of freshly egested pellets. 4. Faecal pellets of Gammarus and Simulium are eaten by stream invertebrates and are sites of microbial breakdown. Faecal pellets are a source of organic matter for benthic invertebrates, bacteria and, indirectly, for plants.     

Water homeostasis by wild larvae of Manduca sexta

Modulation of faecal water loss is the principal mechanism by which larval Lepidoptera maintain water homeostasis in the laboratory. Is this also true of larvae in nature? We observed 12 fifth‐instar larvae of Manduca sexta feeding on Datura wrightii in the Sonoran Desert, U.S.A. The two main sources of water stress were: evaporative water loss across the cuticle, which appeared to be promoted by increasing body temperatures and decreasing relative humidities during daytime observation periods; and attacks by tachinid flies, which prompted caterpillars to defaecate large quantities of water and to regurgitate digestive fluid onto themselves. In both cases, caterpillars responded by producing drier faecal pellets. A subset of caterpillars consumed water‐rich flower buds of D. wrightii, which led to the production of comparatively wet faecal pellets. These data demonstrate that larval water balance in nature is affected by a variety of biotic and abiotic factors and that larvae respond to these perturbations by modulating the loss of water in the faeces.     

Paleoecology of the Zoophycos producers

Kotake, Nobuhiro 1989 07 15: Paleoecology of the Zoophycos producers. Lethaia , Vol. 22. pp. 327–341. Oslo. ISSN 0024–1164.
Well-preserved Zoophycos and Spirophyton- like burrows occur in the Upper Pliocene deep-sea sediments exposed along the southern coast of Boso Peninsula, central Japan. They consist of an axial tunnel and helically coiled spreite with fecal pellets. In most cases the two kinds of trace fossil are found separately. In several complete specimens, however, the upper and lower portions represent a Spirophyton- like burrow and Zoophycos , respectively. The downward increase in size of the spreite and fecal pellets in a single burrow suggests that the complete Zoophycos was built successively as the producing animal grew. The occurrence of incomplete Zoophycos may have resulted from post-mortem destruction by echinoid locomotion and turbidity currents. In some cases, the uppermost portion of the axial tunnel is covered with a thin tuff layer. Fecal pellets in such burrows consist of the same tuffaceous material which must have originated from the overlying tuff layer. This fact indicates that the burrow producer did not feed on organic matter within the sediments but foraged detritus on the sea floor. The animal could probably stretch a part of the body from the top of the axial tunnel for feeding and systematically pack the fecal pellets into the sediments. Such segregation between the feeding place and the excretory space is interpreted as an efficient feeding strategy for the detritus-feeding burrowers in the deep sea. D Zoophycos, Spirophyton-like burrow, paleoecology, feeding and excretory behavior, Boso Peninsula, Japan .     

Trilobites and minute ovoid pellets in a burrow (Ordovician,llanvirnian, Czech Republic)

Old collections from the Ordovician of the Barrandian area (Czech Republic) have yielded a probable vertical burrow that contains several dozen specimens of the pliomerid trilobite Placo‐paria (Placoparia) cambriensis Hicks, some of them enrolled. The fill of the burrow (classified as ?Skolithos isp.) also contains minute ovoid pellets corresponding to the ichnotaxon Tomaculum cf. problematicum Groom. The enrollment of a portion of the trilobite exoskeletons might reflect a defensive response. The pellets may be interpreted as fecal material or, less probably, as eggs. The exoskeletons and the pellets might have been mechanically trapped into the open burrow, or their concentration may have resulted from biological relationships between the tracemaker and the trilobites.     

Changes in microbial biomass,respiration and nutrient status of beech (Fagus sylvatica) leaf litter processed by millipedes (Glomeris marginata)

The effect of processing of beech leaf litter (Fagus sylvatica L.) of different ages by the diplopodGlomeris marginata (Villers) on status and turnover of microorganisms was investigated in the laboratory. Microbial biomass, basal respiration and metabolic quotient of litter-material from three different beechwood sites of a basalt hill forming a gradient from basalt (upper part of the hill) to limestone (lower part of the hill) were determined each season (February, May, August and November). The same microbial parameters were also measured after these litter materials had been processed byG. marginata (faecal pellets of an average age of 4 days). Short-term changes in microbial biomass and respiration in leaf material and faecal pellets from February and August were investigated after 1, 2, 5, 10, 20 and 40 days of incubation. The ergosterol content of August samples was determined. Processing of beech leaf litter byG. marginata increased microbial biomass in February and May but reduced microbial biomass in August and November. It was concluded that processing of litter materials in February and May increased accessibility of carbon resources to microorganisms by fragmentation. In contrast, in litter materials from August and November carbon resources were depleted and fragmentation by diplopods did not increase availability of carbon resources. Addition of carbon (glucose) and nutrients (nitrogen and phosphorus) to litter and faecal pellets indicated that processing of beech litter reduced nutrient deficiency of the microflora. Ergosterol content in faecal pellets was reduced strongly after beech leaf litter processing byG. marginata, indicating a decrease in fungal biomass. Presumably, in faecal pellets bacteria flourished at the expense of fungi.     

Gut fluorescence in herbivorous copepods: an attempt to justify the method

Recently the gut fluorescence technique has been critisized because of the possible degradation of chlorophyll into nonfluorescent derivatives during passage through copepod guts and changes of the gut passage time with food concentration. Here pigment budgets have been calculated in 6 experiments with Calanus finmarchicus CIV caught 2 km offshore of the Murmansk Marine Biological Institute (the Barents Sea, Dalnije Zelentsi) in September 1992. Copepods were fed with culture of Platymonas viridis at different concentrations. Gut pigment and ingestion rate increased with food concentration in a similar way. On average between 78% and 89% of ingested chlorophyll was recovered in the guts and faecal pellets. No trend for a greater loss of fluorescence at low food concentration than at high was observed. Pigment content of faecal pellets incubated in filtered seawater decreased by 20–30% in the first 7–12 h and by up to 60% in 48 h. The decline of pigment content was accompanied by a rapid bacterial growth (by a factor of 3 in 48 h). Gut passage time increased with decreasing food concentration (from 40 min at 9 µg pigm l^–1 to 64 min at 0.9 µg pigm l^–1). These results together with some data by other authors suggest that the gut fluorescence method can be used to estimate in situ grazing rate providing gut passage time is measured properly and there are no losses of faecal material. However, careful consideration should be given to the previous feeding history of copepods.     

Studies on the food and feeding habits of soil oribatei in a black pine plantation

Summary Food preferences and feeding behaviour of abundant species of oribatid mites in a black pine plantation have been studied by soil sectioning technique. It is suggested that Microtritia minima, Rhysotritia duplicata and Phthiracarus sp. play an important role in the mechanical breakdown of decaying litter and, by contributing to the humification process, help in the accumulation of plant nutrients. Due to poor mobility their contribution to fungal spore dissemination is insignificant. Chamobates incisus was determined to be a fungivorous species while no exact information could be obtained about the precise food of Tectocepheus velatus. Rest of the species seemed to consume large quantities of decaying litter but in view of their low populations throughout, presumably they do not contribute appreciably in the humification process.The speed of decomposition of faecal pellets seemed to be governed by the type of food ingested. The role of oribatid fauna in the litter and soil ecosystems is discussed.     

Copepods grazing on <Emphasis Type="Italic">Coscinodiscus wailesii</Emphasis>: a question of size?

Grazing of female copepods, Acartia clausi and Temora longicornis, on the large centric diatom Coscinodiscus wailesii, was studied in the laboratory. While A. clausi females did not feed on C. wailesii, T. longicornis showed a skilful handling of these large algae. The cells were not completely ingested but copepods bit a small piece out of the silica wall and then ingested the cell content only. Faecal pellet analyses showed little remains of the silica walls, and most of the content could only be classified as undefined matter. Therefore the general analyses of faecal pellets and gut content of copepods from the field must be interpreted with caution.     

Iberian Rock Lizards (Lacerta monticola cyreni) Assess Conspecific Information Using Composite Signals from Faecal Pellets

A field and laboratory study was performed to analyse the role of excrement deposited on the substrate in intraspecific communication of the Iberian rock-lizard (Lacerta monticola cyreni). In the field, lizards selected specific sites on rocks to deposit faecal pellets, probably in order to facilitate visual location of pellets by conspecifics. Differential tongue flick rates to chemicals presented on cotton swabs demonstrated that male lizards can detect and discriminate between self-produced scents from faecal pellets and those of other conspecific males. In a subsequent experiment, male lizards were tested in a chamber with two platforms containing a faecal pellet of other male on one side and a control artificial pellet on the opposite side. Males spent significantly less time on the side containing the faecal pellet, suggesting that the decision of where to stay may depend on the presence of faecal pellets. Smaller males moved less than larger males on the experimental side whereas on the control side body size did not influence the proportion of time moving. The ability to discriminate chemicals from faeces, and the effects of faecal pellets on lizard behaviour, suggests that faeces might act as composite signals (visual and chemical) in the intraspecific communication of this lizard.     

Periphyton responds differentially to nutrients recycled in dissolved or faecal pellet form by the snail grazer Theodoxus fluviatilis

1. We aimed to separate the effects of grazers on periphyton via grazing from that of nutrient recycling from their faecal pellets. 2. We set up three different experimental treatments (snails/no snails/faecal pellets) and sampled over 16 days. The ‘snail’ treatment contained a low density (snail biomass c. 14 g^?2) of the gastropod grazer Theodoxus fluviatilis and the ‘faecal pellet’ treatment received the same amount of faecal pellets as were produced in the ‘snail’ treatment. Whereas the ‘faecal pellet’ treatment provided extra nutrients to periphyton from the faeces, the ‘snail’ treatment provided nutrients in the form of both faeces and in excreta. There was also direct grazing on periphyton in the ‘snail’ treatment. The ‘no snail’ was not grazed and received no nutrients in faeces or excreta. 3. We measured periphyton C, N and P content, chlorophyll‐a (chl‐a), primary production, bacterial biomass, bacterial production and bacterial respiratory activity. In the water column we measured dissolved inorganic N and soluble reactive P. 4. Snails increased the amount of dissolved inorganic N in the water. On day 16, the periphyton N : P ratio in the ‘faecal pellet’ treatment was lower, and periphyton P content was higher, than in the other two treatments. N : P ratios decreased over time in the ‘faecal pellet’ treatment. Primary and bacterial production were positively correlated in all treatments. 5. Algal chl‐a and primary production of periphyton per unit area and periphyton chl‐a : C ratios increased over the 16 day in the ‘snail’ treatment, and thus excretion of dissolved N by snails had a stronger positive effect on the periphyton community than N and P in faecal pellets. 6. Our data show that excretion and egestion can have different effects on periphyton, probably because of the higher proportion of dissolved N in excreta and the higher proportion of P recycled in faecal pellets. The relative effect of nutrients recycled in egesta or in excretions, probably depends on the form of nutrient limitation of the periphyton. Further, the different components of the periphyton matrix could react differently to the different forms of nutrient recycling. 7. We conclude that direct grazing effects are less important than nutrient effects when nutrients are limiting and grazing pressure is low. Further, the spatial separation of different grazing effects can lead to differences in periphyton production and nutrient stoichiometry. This might be an explanation for the patchiness of periphyton in nature.     

Ingestion of live filamentous diatoms by the Great Lakes amphipod,Diporeia sp.: a case study of the limited value of gut contents analysis

Individuals of the Great Lakes amphipod, Diporeia sp. (formerly named Pontoporeia hoyi) were collected from a 45-m deep station in southeastern Lake Michigan and isolated in small laboratory feeding vessels at 4 °C, after the animals had voided their guts over a 24-hour period. Over a 20-day period, following introduction of a single ration of live cells of the filamentous diatom, Melosira varians, 9 of 10 animals had ingested this material, and 7 of these 9 individuals had deposited fecal pellets. Subsequent examination of gut contents and fecal pellets showed that although animals had ingested whole algal cells/filaments, little of the material in gut contents or fecal pellets bore any identifiable structural similarity to cells/filaments prior to ingestion. The results suggest that earlier studies of pontoporeiid gut contents may seriously underestimate the importance of algal components in the amphipod's diet and imply that Diporeia sp. growth and production may be more closely linked to primary production than previously thought.     

Proof of concept for a novel insecticide bioassay based on sugar feeding by adult Aedes aegypti (Stegomyia aegypti)

Aedes aegypti L. (Stegomyia aegypti) (Diptera: Culicidae) is the principal vector of dengue and yellow fever viruses in tropical and subtropical regions of the world. Disease management is largely based on mosquito control achieved by insecticides applied to interior resting surfaces and through space sprays. Population monitoring to detect insecticide resistance is a significant component of integrated disease management programmes. We developed a bioassay method for assessing insecticide susceptibility based on the feeding activity of mosquitoes on plant sugars. Our prototype sugar‐insecticide feeding bioassay system was composed of inexpensive, disposable components, contained minimal volumes of insecticide, and was compact and highly transportable. Individual mosquitoes were assayed in a plastic cup that contained a sucrose‐permethrin solution. Trypan blue dye was added to create a visual marker in the mosquito's abdomen for ingested sucrose‐permethrin solution. Blue faecal spots provided further evidence of solution ingestion. With the sugar‐insecticide feeding bioassay, the permethrin susceptibility of Ae. aegypti females from two field‐collected strains was characterized by probit analysis of dosage‐response data. The field strains were also tested by forced contact of females with permethrin residues on filter paper. Dosage‐response patterns were similar, indicating that the sugar‐insecticide feeding bioassay had appropriately characterized the permethrin susceptibility of the two strains.     

Bacterial feeding by the freshwater bryozoan Plumatella fungosa (Pallas, 1768).

The present study demonstrates for the first time the capacity of a bryozoan to feed on bacteria. Qualitative feeding tests were performed in laboratory conditions with Plumatella fungosa raised from statoblasts and fed with formazan-coloured Escherichia coli. They establish that bacteria were not only ingested but digested as shown by their transit in the digestive tract and the presence of broken bacteria in the faecal pellets. The ingestion rate of E. coli was determined by measuring bacterial removal in a vessel containing a colony of P. fungosa collected from a pond. It attained 10³ cells per zooid during the first hour of the experiment, for an initial bacterial concentration of 5.5 × 10⁴ cells ml⁻¹. The filtration rate was estimated at 0.0246 ml zooid⁻¹ h⁻¹ . These results indicate the ecological role of bryozoans in water purification.     

Krill diet affects faecal string settling

Summary Free-floating sediment traps used on a transect from Scotia Sea to Weddell Sea collected larger, more degraded, krill faecal strings in the deeper (150 m) than in the 50 or 75 m traps. The smallest faecal strings were only present in the shallower traps. Sinking velocity of smaller faecal strings was — as expected — much lower than for larger ones, with a total range of 50 to 800 m · day ^–1 for faecal string volumes of 0.007 to 0.53 mm³. Krill feeding largely on diatoms produced faeces with higher settling velocity than those feeding on non-diatom phytoplankton. Smaller krill faecal strings do not leave the upper mixed layer. Potential settling velocities as measured in settling tubes (without turbulence), may in this respect be misleading. Small oval faecal pellets of unknown origin showed relatively high settling velocities (80 to 250 m·day^–1 for 0.002 to 0.013 mm³) due to higher compaction and lower form resistance to sinking.Data presented here were collected during the European Polarstern Study (EPOS) sponsored by the European Science Foundation     

Fractionation of stable isotopes in the Arctic marine copepod Calanus glacialis: Effects on the isotopic composition of marine particulate organic matter

Fractionation of δ¹³C and δ¹⁵N between food, consumer, and faecal pellets was studied in the Arctic marine copepod Calanus glacialis Jaschnov, fed with isotopically distinct algal monocultures. Temporal variations in δ¹³C and δ¹⁵N of copepods that were fed ice algae and phytoplankton followed those of a control group consisting of starved animals. There were no significant trends in the δ¹³C and δ¹⁵N values of copepods that were starved for 42 days, suggesting that the isotopic composition of non-lipid body tissues is unaffected by the metabolic processes during prolonged periods of starvation. The stable isotopic composition of starved copepods therefore seems to reflect food consumed during the previous period of feeding and growth. Faecal pellets produced by feeding copepods were depleted in ¹³C and ¹⁵N by 6.3-11.2‰ and 0.7-9.1‰, respectively, relative to the food ingested. These results indicate that faecal pellet production is an important pathway for the trophic fractionation of δ¹³C, whereas other fractionation pathways, such as excretion of ammonia, may be relatively more important for δ¹⁵N. The strong depletion of ¹³C in faecal pellets compared to the food suggests that grazing by herbivorous copepods on primary production adds to the variability of δ¹³C in marine particulate organic matter.     

Food web transfer of plastics to an apex riverine predator

As a rapidly accelerating expression of global change, plastics now occur extensively in freshwater ecosystems, yet there is barely any evidence of their transfer through food webs. Following previous observations that plastics occur widely in their prey, we used a field study of free‐living Eurasian dippers (Cinclus cinclus), to test the hypotheses that (1) plastics are transferred from prey to predators in rivers, (2) plastics contained in prey are transferred by adults to altricial offspring during provisioning and (3) plastic concentrations in faecal and regurgitated pellets from dippers increase with urbanization. Plastic occurred in 50% of regurgitates (n = 74) and 45% of faecal samples (n = 92) collected non‐invasively from adult and nestling dippers at 15 sites across South Wales (UK). Over 95% of particles were fibres, and concentrations in samples increased with urban land cover. Fourier transform infrared spectroscopy identified multiple polymers, including polyester, polypropylene, polyvinyl chloride and vinyl chloride copolymers. Although characterized by uncertainty, steady‐state models using energetic data along with plastic concentration in prey and excreta suggest that around 200 plastic particles are ingested daily by dippers, but also excreted at rates that suggest transitory throughput. As some of the first evidence revealing that plastic is now being transferred through freshwater food webs, and between adult passerines and their offspring, these data emphasize the need to appraise the potential ecotoxicological consequences of increasing plastic pollution.     

Fate of resting cysts of Alexandrium spp. ingested by Perinereis nuntia (Polychaeta) and Theola fragilis (Mollusca)

The ingestion of resting cysts of Alexandrium spp. by Perinereis nuntia (Polychaeta) and Theola fragilis (Mollusca) was experimentally examined in the laboratory. P. nuntia and T. fragilis were cultured in bottom sediment containing a high density of Alexandrium cysts under dark conditions. Moreover, to evaluate the degree and consequence of being ingested, the density of cysts in the control sediment (no macrobenthic organisms) and the germination capability of the cysts in the faecal pellets of the two species of macrobenthos were examined.Cysts in the culture sediment were found to be ingested by both P. nuntia and T. fragilis. No difference in the density of cysts between the sediments cultured with and without P. nuntia was observed. However, the density of cysts in the sediments with T. fragilis decreased by 24% compared to the density in the control sediment. It is possible that most of the cysts ingested were digested by T. fragilis. The rate of Alexandrium cyst digestion by this species is estimated 594 cysts/individual/day. It is estimated that 91% of the cysts ingested by T. fragilis were partially or totally digested and only 9% were excreted in a viable state during the experiment. Thus, T. fragilis has a stronger affect on the abundance of Alexandrium cysts compared with P. nuntia.No significant difference was observed between the germination success of the cysts from faecal pellets of P. nuntia and T. fragilis compared to the cysts in the control sediment. If, however, the necessary light for the cysts to germinate is cut off by being enclosed within the faecal pellet, the germination rate of cysts from the faecal pellets may be suppressed.