Dynamics of Copepod Faecal Pellets in Relation to a Phaeocystis Dominated Phytoplankton Bloom: Characteristics, Production and Flux

Copepod faecal pellet characteristics and production were measuredin spring 1995, 1996 and 1997 in the North Sea Southern Bightin order to define changes due to the development of the phytoplanktonbloom. Changes were related to the succession from diatomsto a Phaeocystis sp. bloom. Mean monthly pellet productiondecreased during the Phaeocystis bloom development to 0.27 pelletsind. ^–1 h ^–1, approximately 80% lower than beforeand after the bloom. Although phytoplanktonic pigments showedsignificant differences between inshore and offshore stations,there was no such significant difference for faecal pellet production.Faecal pellet sinking-rate decreased from 100 to 70 m day ^–1during the transition from a diatom- to a Phaeocystis-dominatedbloom. This was due to a decrease in pellet density and/or adecrease of the pellet volume. These results supported the ideaof lower feeding of copepods under Phaeocystis bloom conditions.As mean seasonal density of copepod faecal pellets was higher(1.37 g cm ^–3) than in other seas, accidental ingestionof sedimentary material as the cause of this high density isdiscussed.     

Leader of the pack: faecal pellet deposition order impacts PCR amplification in wombats

DNA sourced from faeces is notoriously less reliable than that from tissue. Hence, understanding whether faecal pellet quality varies within faecal piles may be important for sample selection. We hypothesized that the order in which faecal pellets are deposited may influence microsatellite polymerase chain reaction (PCR) amplification success from sampled faeces, more specifically, that first pellets deposited will have signatures of greater success than later ones. In a first test of the hypothesis, first and later-deposited pellets, as determined from the direction of footprints, were collected from fresh (overnight) faecal piles of northern hairy-nosed wombats (Lasiorhinus krefftii). DNA extracts were typed for seven microsatellite loci. We found that faecal deposition order significantly affected optical density of bands on autoradiographs (a measure of PCR amplification success) when the first faecal pellet was compared with the last one, but not when the first pellet was only distinguishable from later ones. The absence of a difference in amplification rate between first and later pellets is likely a reflection of the overall high amplification success in this study. That first pellets deposited yield more product suggests they contain more intestinal cells. Although further comparisons are needed, these results may inform sample selection in species for which success of microsatellite PCR amplification of faecal DNA is low. Deposition order may have more of an impact on amplification success and genotyping errors as faecal age increases.     

The fate of faecal pellets in the North Sea

During an intensive survey in May/June 1986, 129 stations in the North Sea were examined in different water depths with respect to several hydrographical parameters. The relations of planktonic faecal pellets to food (chl-a) and producers (zooplankton-wet weight) as well as to temperature, salinity and water depth were investigated. The amount of faecal pellets was positively correlated with chl-a and zooplankton. The length of the faecal pellets was negatively correlated with water depth indicating a degradation during sinking. Hardly any formed faecal material was detectable under 100 m water depth. The ratio of pellets to zooplankton was positively correlated to chlorophyll and influenced by daytime, indicating diel variations in pellet production. It is assumed that in summer most of the planktonic faecal material is disintegrated in the upper water layer and the role of faeces in sedimentation is minor.     

Production and fate of faecal pellets during summer in an East Antarctic fjord

The abundance of small faecal pellets is high in marine waters. Little is known, however, about the processes governing their production and fate in the water column. We investigated faecal pellet production and flux in relation to the phytoplankton and copepod assemblages present in Ellis Fjord, Antarctica. Results show that the phytoplankton community shifted from a dominance of diatoms to that of a cryptomonad species during late January. This coincided with an increase in abundance of the small copepods Paralabidocera antarctica and Oithona similis, although Oncaea curvata was still the dominant species. The mean faecal pellet flux was 9943 pellets m^–2 d^–1. Only 37% of the faecal pellet flux at 5 m sedimented to 10 m depth, 15% to 20 m, and 12% to 40 m depth. Our results suggest that recycling of faecal pellets by copepods contributes to this decreased flux with increasing depth, which concurs with results from large scale oceanic studies. Additionally, we propose that the summer ice melt changes the physical characteristics of the water column and the phytoplankton species abundance and distribution; both of which potentially impact on the distribution and abundance of copepods, thereby regulating faecal pellet flux.     

Monitoring ungulates in steep non-forest habitat: a comparison of faecal pellet and helicopter counts

Faecal pellet counts have been widely used to monitor the abundances of introduced ungulates in New Zealand, but ground-based sampling cannot be conducted safely in the steep non-forest habitats that are common in New Zealand's Southern Alps. Helicopter counts may be an effective technique for monitoring ungulates in steep non-forest habitat. We evaluated the relationship between faecal pellet and helicopter counts of ungulates (primarily feral goat Capra hircus) at 12 non-forest sites in the Southern Alps. Within each site we counted the numbers of ungulates from a helicopter on three occasions and the number of intact faecal pellets along 30 transects. Mean observed densities of feral goats derived from helicopter counts ranged from 0.0 to 20.2 km^?2. There was a positive curvilinear (concave down) relationship between faecal pellet and helicopter counts. Compared with faecal pellet counts, helicopter counts were cheaper, could identify ungulate species and provided estimates of absolute density. Helicopter counts are a cost-effective method for monitoring ungulates in the steep non-forest habitats of New Zealand's Southern Alps.     

Post-bloom feeding of Calanus finmarchicus copepodites: Selection for autotrophic versus heterotrophic prey

Feeding and faecal pellet production of late copepodite stages of Calanus finmarchicus were measured in mixtures of cultured autotrophic and heterotrophic food, as well as in a natural post-bloom plankton assemblage, in order to evaluate food selection and its potential effect on sedimentation of organic matter. Calanus finmarchicus consistently selected for diatoms, both in mixtures with the heterotrophic dinoflagellate Oxyrrhis marina, and in natural seston containing dinoflagellates, ciliates and flagellates. Similarly, the filtration, ingestion and faecal pellet production rates were significantly higher feeding on diatoms than when feeding on other food species. Calanus finmarchicus selection appeared relatively inflexible, so that changes in seston composition induced large changes in diet quantity and composition. Our results support the traditional view of C. finmarchicus as a major grazer of diatoms, and suggest potentially high post-bloom faecal pellet production rates.     

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.     

A Mechanistic Individual-Based Model of the Feeding Processes for Oikopleura dioica

A mechanistic physiological model of the appendicularian Oikopleura dioica has been built to represent its three feeding processes (filtration, ingestion and assimilation). The mathematical formulation of these processes is based on laboratory observations from the literature, and tests different hypotheses. This model accounts for house formation dynamics, the food storage capacity of the house and the gut throughput dynamics. The half-saturation coefficient for ingestion resulting from model simulations is approximately 28 and is independent of the weight of the organism. The maximum food intake for ingestion is also a property of the model and depends on the weight of the organism. Both are in accordance with data from the literature. The model also provides a realistic representation of carbon accumulation within the house. The modelled half-saturation coefficient for assimilation is approximately 15 and is also independent of the weight of the organism. Modelled gut throughput dynamics are based on faecal pellet formation by gut compaction. Model outputs showed that below a food concentration of 30 , the faecal pellet weight should represent a lower proportion of the body weight of the organism, meaning that the faecal pellet formation is not driven by gut filling. Simulations using fluctuating environmental food availability show that food depletion is not immediately experienced by the organism but that it occurs after a lag time because of house and gut buffering abilities. This lag time duration lasts at least 30 minutes and can reach more than 2 hours, depending on when the food depletion occurs during the house lifespan.     

Minimum sampling effort for reliable non-invasive estimations of excretion abundance of Elaphostrongylus cervi L1 in red deer (Cervus elaphus) populations

Faecal surveys are commonly used as non-invasive means to evaluate population abundance of animals as well as comparable indexes of prevalence and intensity of diseases between populations, especially macroparasites. While faecal surveys are among one of the simplest means to perform these evaluations, they are time consuming and labour intensive. The present study evaluated 80 red deer (Cervus elaphus) faecal samples collected in two study sites for the presence and abundance of first-stage larvae of the nematode Elaphostrongylus cervi and established pools of samples for epidemiological analysis. The analysis of 20-30 individual samples would produce a reliable estimate of the 'true' prevalence, and the error of the smaller sample size only doubled that of the 80 reference samples. The analysis of 5 pools of 5 pellet groups each, or of 4 pools of 10 pellet groups each, provided a reliable estimation of the 'true' excretion abundance estimated by the analysis of all 80 samples. These pools comprise a cost-effective and dependable alternative for measuring and obtaining comparable abundances of parasitic faecal excretion stages in red deer populations, which is very valuable for epidemiological and ecological research as well as for management purposes.     

Synthesis of protein in the pancreas. II. The role of ribonucleoprotein in protein synthesis

1. The ribonucleoprotein of the microsome fraction which sediments at 40,000 R.P.M. as a pellet (and which is referred to as the pellet material) has been studied with reference to its role in protein synthesis in the pancreas. 2. In pellet material nucleic acid and protein form a definite complex as shown by its electrophoretic behavior and unchanging composition under various conditions. 3. Protein of pellet material is not especially rich in the diamino acids. 4. Evidence is brought forward indicating that the protein component of pellet material takes part in the general process of protein synthesis in the cell. (a) The well known correlation between quantity of RNA and rate of protein synthesis in a tissue implicates the protein of the pellet material, for most of the RNA in the pancreas and other tissues is in this material. (b) Uptake of isotopically labelled glycine by the pellet material, confirming results of previous workers, is for short periods greater than in other protein fractions. (c) Comparing the pellet materials of pancreas, liver, and kidney-three tissues with vastly different rates of protein synthesis, in the sequence given-there is a correlation between the quantity of RNA in the pellet and the rate of protein synthesis in the tissue; a similar correlation between quantity of RNA in the pellet material and rate of N(15)-glycine uptake by the protein component of the pellet; and finally, the level of uptake by total protein varies with the tissue and is related to the uptake of N(15)-glycine by protein of the pellet. 5. In the pancreas a distinction can be made between proteins synthesized for secretion and the nucleoprotein of the pellet (not found in the secretion) which, however, takes part in the synthetic process, as shown by the fact that the N(15) uptake by protein of the pellet is increased when the synthesis of digestive enzymes is stimulated by secretion. 6. The time course of N(15) uptake by proteins of the pancreas indicates that pellet protein serves as precursor material in the synthesis of the secretory proteins. 7. Rate of uptake of N(15)-glycine by the purines of RNA of the pellet material is not correlated with uptake by the protein. 8. The uptake of C(14)-alanine by an in vitro system of microsomes + mitochondria is impaired by preincubation of the microsomes with ribonuclease. This is direct experimental evidence for the dependence of protein synthesis upon the presence or intactness of ribonucleic acid in the microsomes.     

The dispersal of vascular plants in a forest mosaic by a guild of mammalian herbivores

Endozochorous seed dispersal by herbivores can affect plant spatial dynamics and macroecological patterns. We have investigated the number and species composition of viable seeds deposited in faeces of a full guild of macroherbivores (four deer and two lagomorph species) in a forest in eastern Britain. One hundred and one plant species germinated from faecal pellet material, 85 of which were among the 247 vascular plant species recorded in the forest. However, three species – Chenopodium album, Urtica dioica and Agrostis stolonifera – comprised 56% of the seedlings recorded. Of the species recorded in faecal samples, 36% had no recognised dispersal mechanism, while very few (7%) were adapted to endozoochorous dispersal (fleshy fruit or nut). The number of species dispersed by the herbivores was ranked Cervus elaphus and Dama dama (96) > Capreolus capreolus (40) > Muntiacus reevesi (31) > Oryctolagus cuniculus (21) > Lepus europaeus (19), with the other taxa dispersing subsets of those dispersed by C. elpahus and D. dama. The invasive M. reevesi deposited the fewest seeds per gram of faecal pellet material (0.4 g⁻¹) and hence fewer seeds per unit area than other deer species despite their numerical dominance, while C. elaphus/D. dama deposited the most (0.43 seeds m⁻² year⁻¹). Due to differences in faecal seed density among habitats combined with the ranging behaviour of animals, more seeds were deposited in younger stands, enhancing the potential contribution of macroherbivores to population persistence by dispersal and colonisation in a successional mosaic. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Estimating dung decay rates of roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>) in different habitat types of a Mediterranean ecosystem: an information theory approach

For elusive species living in concealing habitats (e.g. deer in a forest habitat), indirect methods such as faecal pellet counts are considered more practical means of estimating population density and abundance. Accurate estimation of deer density using the faecal standing crop (FSC) method necessitates the reliable estimation of the mean time to decay of pellet groups present during the survey. Mean time to decay is generally habitat specific, and separate estimations should be made for each habitat type in the study area. In a confined mountainous area of Greece, the habitat-specific mean time to decay of roe deer pellet groups was estimated by locating and marking fresh pellet groups on several dates in the lead up to an FSC survey and returning to the marked signs at the time of the survey to record whether or not each pellet group had survived. Several logistic models were fitted to the data, and estimations were based on a multi-model inference (MMI) approach according to information theory. The highest mean time to decay was estimated in coniferous forests, while mid-ranged values were found in maquis shrubs, and the lowest mean time to decay was observed in open areas. MMI by model averaging, based on Akaike weights, is recommended for making robust parameter estimations and for dealing with uncertainty in model selection.     

Structural observations on the alimentary canal of Paranthessius anemoniae, a copepod associate of the snakelocks anemone Ammonia sulcata

Light and electron microscopy has shown the alimentary canal of Paranthessius to be composed of clearly defined foregut, midgut and hindgut regions. The spacious foregut is cuticle-lined and separated from the midgut by a valve. The midgut epithelium is composed of columnar cells with an apparent secretary/absorptive rôle, and amoeboid cells thought to engulf material from the lumen. The amoeboid cells have large electron-dense central vacuoles containing carbohydrate-and protein-staining material. These cells appear to be sloughed off into the lumen to form part of a faecal pellet. Apart from their digestive rôle the midgut cells store lipid and it is considered possible that they have an osmoregulatory function. The hindgut epithelium cell type, lacks a cuticular layer and is thought to be mainly concerned with absorption. The alimentary canal is surrounded by strands of longitudinal and circular muscle.     

The use of faecal counts for estimating populations of wall lizards (Podarcis muralis)

Measurements of the rates at which droppings of wall lizards ( Podarcis muralis ) on Jersey appeared in, and disappeared from, the environment made it possible to formulate a simple mathematical model for the dynamics of faecal pellet populations. The model shows how, for a given lizard population, the number of droppings changes with time according to weather conditions. It was used to estimate lizard densities at a number of sites from daily pellet counts. There were significant differences in the densities of lizards between sites; possible reasons for these are discussed.     

Faecal pellets as burrow markers: intra- and interspecific odour recognition by western plethodontid salamanders

Chemical communication is widespread among plethodontid salamanders (Caudata: Plethodontidae), but little information exists on the role of odours in interspecific competition in general and among species in western North America in particular. The present study examined the potential of faecal odours for intra- and interspecific communication among sympatric plethodontids in two-choice tests in the laboratory. In experiment 1, Plethodon vehiculum and Aneides ferrus from Vancouver Island, B.C., Canada, were presented with two burrows marked with (1) a faecal pellet of male P. vehiculum versus a control clay pellet, and (2) a faecal pellet of male A. ferreus versus a control pellet. In experiment 2, responses of P. vehiculum, P. dunni and P. vandykei from Washington, U.S.A., were tested towards faecal pellets of conspecific males and females, and towards pellets of congeneric males. Both P. vehiculum and P. dunni distinguished odours of conspecific males and females, based on their behavioural responses towards faecal and control pellets. Only P. dunni, however, avoided burrows marked with faeces of conspecific individuals. In contrast, neither A. ferreus nor P. vandykei appeared to distinguish faecal odours of conspecific salamanders from control pellets. In tests with odours of heterospecific individuals, P. dunni and P. vehiculum distinguished odours of each other, and P. vandykei distinguished odours of P. vehiculum. The data from these two experiments suggest that P. dunni use faecal pellets as territorial markers both in intraspecific communication and in interspecific encounters with P. vehiculum.     

Differentiation of animals from different age classes by means of pellet size: Assessment of a field method in European rabbits

Estimating population age structures by faecal pellets sizes is a commonly used field method in some mammal species. We examined the validity of this method in European rabbits based on 1113 pellets from 226 animals with known age, by measuring the intra-individual variation in pellet size and studying the explained variance of calibration curves describing the relation between pellet size and individual age. In addition, we applied a simulation model in order to estimate the accuracy of this method. Pellet size showed a high intra-individual variation and was only moderately correlated with the animals’ age. Modelling revealed that the population age structure assessed by this method deviated considerably from the given structure, indicating a systematic estimation error. We conclude that this method can lead to strongly biased results, restricting its validity. We provide estimation errors, which might be considered if estimates of age structure in wild rabbits populations based on faecal diameters are conducted.     

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.     

The disappearance of muntjac (Muntiacus reevesi) and roe deer (Capreolus capreolus) pellet groups in a pine forest of lowland England

Reliable knowledge of the disappearance rate of faecal pellets is essential for converting pellet density to deer density when using standing-crop pellet-group counts. Disappearance of muntjac and roe deer pellet groups was monitored in four growth stages of a pine forest of lowland England over a 15-month period. Time to disappearance of the pellet groups (days) of both species significantly differed between habitats and months; it was shorter in late summer to early autumn and in habitats with more ground vegetation. Muntjac pellet groups disappeared more quickly than roe deer pellet groups. Time to disappearance of roe deer pellet groups was negatively correlated with air and grass temperature in pre-thicket and pre-fell habitats, while time to disappearance of muntjac pellet groups was negatively correlated with frequency of rainfall and positively correlated with the run of wind (air passage over a site within a 24-h period measured in km) in pre-thicket habitats. It is the time of the standing-crop pellet-group counts and the disappearance rate of pellet groups deposited in different months and habitats that determine the appropriate method for conversion of pellet-group density to deer density.     

Salamander territoriality: pheromonal markers as advertisement by males

A laboratory experiment was performed to test the hypothesis that male red-backed salamanders (Plethodon cinereus) use pheromones contained in faecal pellets to identify male-marked territories. Each of 25 males was tested randomly under four conditions: (1) a burrow marked with its own faecal pellet versus one marked with a conspecific's pellet; (2) own-marked versus surrogate-marked burrows (the surrogate being a pellet of wadded paper); (3) conspecific-marked versus surrogate-marked burrows; and (4) a control of two surrogate-marked burrows. Males spent significantly more time in own-marked than in conspecific-marked burrows and significantly more time in surrogate-marked than in conspecific-marked burrows. Males favoured own-marked over surrogate-marked burrows. No position bias was found in the control. Males spent significantly more time nose-tapping (olfactory sampling) to a conspecific's pellet when it was paired with a surrogate but showed no differences in the other three tests. Significantly more time was spent in a submissive posture in front of the conspecific-marked burrow than in front of either their own-marked or the surrogate-marked burrows; no difference was found between own-marked versus surrogate-marked burrows or in the control. Time spent in the threat posture did not differ significantly between burrows in any condition. These data permit the inferences that males of P. cinereus use faecal pellets to mark and identify territories, avoid or display submissively toward burrows marked by conspecific males, and prefer own-marked shelters.     

The diet of the diadem leaf-nosed bat Hipposideros diadema: confirmation of a morphologically-based prediction of carnivory

The diet of Hipposideros diadema was investigated over three seasons at two sites on Cape York Peninsula, Australia using faecal analysis (at both sites) and prey remains identification (at one site). The possibility that this species feeds on terrestrial vertebrates, a behaviour here referred to as carnivory, was suggested by the similarity of three of its morphological features with those of eight of the 10 species of bats known to exhibit carnivory.
The study confirmed that H. diadema is at least occasionally carnivorous. Bird feathers were found in faeces at both sites; however, their occurrence was limited to a collection of faecal pellets from the early dry season at Iron Range and a single pellet from the wet season at Chillagoe. The birds taken could not be identified to family or species. Coleoptera, Lepidoptera and various orthopteroid orders were the main insect taxa in faecal pellets. The frequency of these taxa in the diet varied significantly among the three seasons at both sites. Analysis of prey remains indicated that large, hard-bodied insects, mainly cerambycid and scarabaeid beetles and acridid grasshoppers, particularly the locust Gastrimargus musicus , were taken frequently. The mean length of intact beetle elytra collected below roosts was 18.0 mm. No vertebrate material was found in prey remains. Hipposideros diadema is similar to several other bats which exhibit carnivory in preying infrequently on vertebrates. The term 'partial carnivore' or 'occasional carnivore' is suggested for these species.