Size Of Fecal Pellets Research Articles

T3 Transection as a Mouse Model of Bowel Dysfunction after Spinal Cord Injury

Bowel dysfunction, in the form of constipation and/or incontinence, is one of the most prevalent and life-impacting co-morbidities associated with spinal cord injury (SCI) with no long- term treatment available. The extent to which SCI-induced changes in the colon (e.g. inflammation, fibrosis, and reduced enteric neuron density) cause progressive dysfunction is understudied. There remains a significant unmet need to develop strategies to prevent or reverse bowel dysfunction after SCI. This need remains, in part, due to the lack of a mouse model which recapitulates the human condition. We hypothesized that a T3 spinal transection in mice would trigger bowel dysfunction alongside early colonic inflammation and downstream remodeling of the colon musculature as seen in both humans and rats after SCI. Bowel dysfunction was defined as increased number of fecal pellets within the colon, smaller pellet size, and decreased water content in the stool. The number of fecal pellets within the colon increased significantly in animals receiving SCI compared to sham (laminectomy only) injuries by 4 days post injury (dpi) and persisted to 21dpi. Furthermore, fecal pellet size was significantly decreased in the SCI animals at 21dpi and trended toward decreased water content. Together, these functional measurements are indicative of chronic bowel dysfunction after T3 transection. We next molecularly interrogated whole colon tissue for inflammatory cytokine levels and found increased levels of IFN-γ at 4 dpi but not at 21dpi and found increased collagen deposition in the colonic musculature at both 4 and 21 dpi in the SCI versus sham animals. The acute spike in INF-γ and deposition of collagen after injury are consistent with our hypothesis that T3 transection causes acute inflammation followed by remodeling of the colon wall. Establishing this mouse model will enable further interrogation of cell-type specific responses and signaling pathways using transgenic models. T32 Fellowship in Physiology (GM118292) and T32 Fellowship Neurobiology of CNS Injury & Repair (5T32 NS077889) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effect of Diet and Body Size on Fecal Pellet Morphology in the Sea Urchin Lytechinus variegatus

Sea urchins are important inhabitants of many marine ecosystems. They are also an economic resource for many international fisheries and are an important animal model in developmental biology. Sea urchins ingest a variety of plant and animal matter, form a digesta pellet, and produce an egesta (fecal) pellet that contributes to benthic food webs. The size and morphology of fecal pellets produced by various size classes of the sea urchin Lytechinus variegatus fed a variety of natural, vegetable-based, or formulated diets were characterized in terms of two-dimensional area, length (long diameter), width (short diameter), and circularity, as well as by ultrastructure analysis using transmission electron microscopy (TEM). Sea urchins fed natural and vegetable-based ingredients produced a wide variety of irregularly shaped egesta that were loosely surrounded by mucus, whereas urchins fed a formulated diet produced highly circular egesta surrounded by a uniform multilayered mucus coat. Larger urchins (62 ± 3.1 g wet weight) consuming a formulated diet produced egesta that were larger in size than smaller adult (26.5 ± 2.7 g) or juvenile urchins (3.6 ± 0.4 g), with egesta length of 0.93 ± 0.06, 0.75 ± 0.05, and 0.61 ± 0.01 mm, respectively (mean ± 95% confidence interval [CI]; P < 0.001). Ultrastructural analysis of the egesta using TEM image analysis software from urchins consuming formulated diets indicated that pellets contained extensive bacterial communities, ranging from 31% to 69% of the total cross-sectional area of the pellet, with dense communities located near the surface of the pellet (9.51 × 108 cells/cm2). Qualitative examination of the egesta TEM suggested the presence of a diverse bacterial community. Following egestion, these microbial communities are suggested to have an important role in natural food webs, with potential value for integrated multitrophic aquaculture systems.

Fecal Pellet Mass as a Function of Body Size, Color Morph, and Season in Plethodon cinereus (Green, 1818) (Amphibia: Plethodontidae)

In plethodontid salamanders, fecal pellets have a variety of behavioral functions related to chemical communication. We examined how fecal pellet mass in the Eastern Red-backed Salamander (Plethodon cinereus) varies with body size, color morph, and season. Fecal pellet mass increased with salamander size. Striped P. cinereus produced heavier fecal pellets than unstriped P. cinereus. Fecal pellet size tended to be greater in the spring than in the fall. Our results suggest further investigations of the factors governing fecal pellet size in plethodontid salamanders is warranted.

Diet alters rodent fecal pellet size: implications for paleoecological and demographic studies using fecal dimensions

Abstract Measurements of fecal pellet size can provide important information about wild mammals, such as body size and demographic information. Previous studies have not rigorously tested whether diet can confound these measurements. Furthermore, it is unknown whether diet might alter fecal dimensions directly or through changes in animal physiology. Here, we studied three closely related rodent species that differ in natural feeding strategies. Individuals were fed diets that varied in protein and fiber content for 5 weeks. We then measured body size, fecal widths and lengths, and the radius of the large intestine. Diet composition significantly changed fecal widths in all species. High-fiber content significantly increased fecal widths and would cause overestimations of body size if applied to wild feces. Using path analysis, we found that fiber can increase fecal widths both directly and indirectly through increasing the large intestine radius. Protein affected each species differently, suggesting that protein effects vary by species feeding strategy and existing physiology. Overall, diet and large intestine morphology can alter fecal pellet measurements. Studies using fecal measurements therefore must consider these effects in their conclusions.

Carbon and Calcium Carbonate Export Driven by Appendicularian Faecal Pellets in the Humboldt Current System off Chile

The role of appendicularian faecal pellet (FPa) size fractions on coccolithophore-derived particulate organic carbon (POC) and calcium carbonate (CaCO3) export to the deep sea was assessed from sediment traps within a period of ten years (1995–2004) off Coquimbo (CQ, 30°S) and five years (2005–2009) off Concepción (CC, 36°S) in the Humboldt Current System (HCS) off Chile. The composition and size distribution of 1,135 FPa samples from sediment traps deployed at 2,300 and 1,000 m depths showed non-linear, inverse relationships between the FPa size-fractions and their volume-specific POC and CaCO3 contents, which were up to ten times higher for small (<100 µm in diameter) than large (>100 µm) FPa. On average, 13 and 2% of the total POC and CaCO3 fluxes, respectively, were contributed mainly by small FPa (90%), with maxima during the autumn and summer. Thus, a non-linear, exponential model of volume-specific POC and CaCO3 contents of FPa substantially improved vertical flux rate estimates. In the HCS, annual carbon flux based on a non-linear FPa carbon load was double the estimate assuming a linear-volume to carbon load for FPa (345 and 172 kton C y−1). We recommend a widespread consideration of this non-linear model in global carbon estimates.

Impact of temperature and pyrene exposure on the functional response of males and females of the copepod Calanus finmarchicus.

We know very little about the effects of two global stressors, elevated temperature and contaminants, on the grazing of marine copepods. To address this issue, we tested the hypotheses that the individual and combined effects of these two stressors may reduce grazing rates and may depend on food availability and gender. We exposed male and female Calanus finmarchicus copepods to pyrene at two temperatures (10 and 14 °C) and six food concentrations (25-800 μg C Rhodomonas baltica L-1) and measured fecal pellet size, and grazing rate (GR) from pellet production. Males had smaller fecal pellets and lower GR than did females. Temperature and pyrene exposure had no effect on pellet size. Temperature alone had no effect on GR of males, but females had lower GR at elevated temperature. Pyrene-exposed males and females had lower GR only at the food concentrations of 200-800 μg C R. baltica L-1 and those patterns were independent of temperature. Pyrene-induced reduction in GR was stronger in females than in males. The negative effects of both elevated temperature and pyrene may reduce the abundance and trophic success of C. finmarchicus in a warmer, more polluted future.

Changes in the diet composition of fatty acids and fiber affect the lower gastrointestinal motility but have no impact on cardiovascular parameters: In vivo and in vitro studies.

Food and diet are central issues for proper functioning of the cardiovascular (CV) system and gastrointestinal (GI) tract. We hypothesize that different types of dietary FAs affect CV parameters as well as GI motor function and visceral sensitivity. Male Wistar rats were fed with control diet (CTRL), diet supplemented with 7% soybean oil (SOY), SOY+3.5% virgin coconut oil (COCO), and SOY+3.5% evening primrose oil (EP) for 4weeks. The content of insoluble fiber in CTRL was higher than in SOY, COCO, or EP. Body weight gain and food/water intake were measured. At day 28, biometric, biochemical, CV parameters, GI motor function (X-ray and colon bead expulsion test), and visceral sensitivity were evaluated. Changes in propulsive colonic activity were determined in vitro. The colon and adipose tissue were histologically studied; the number of mast cells (MCs) in the colon was calculated. SOY, COCO, and EP had increased body weight gain but decreased food intake vs CTRL. Water consumption, biometric, biochemical, and CV parameters were comparable between groups. SOY increased the sensitivity to colonic distention. All groups maintained regular propulsive neurogenic contractions; EP delayed colonic motility (P<0.01). SOY, COCO, and EP displayed decreased size of the cecum, lower number and size of fecal pellets, and higher infiltration of MCs to the colon (P<0.001). Dietary FAs supplementation and lower intake of insoluble fiber can induce changes in the motility of the lower GI tract, in vivo and in vitro, but CV function and visceral sensitivity are not generally affected.

Fecal DNA, hormones, and pellet morphometrics as a noninvasive method to estimate age class: an application to wild populations of Central Mountain and Boreal woodland caribou (Rangifertaranduscaribou)

Determining age structure of populations is a valuable parameter in wildlife management, but is often difficult to obtain. Here, we tested a noninvasive method via fecal DNA, hormones, and pellet morphometrics to distinguish calf from adult in Central Mountain and Boreal woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)) populations. Annual surveys of fall-sampled Central Mountain caribou were done in Jasper National Park, Alberta, between 2006 and 2011 and winter-sampled Boreal caribou were surveyed in the North Interlake area, Manitoba, between 2004 and 2010. Samples were amplified at 10 microsatellite loci to identify unique individuals and capture histories were used to identify putative calves and adults. Fecal pellets were measured for length, width, depth, dry mass, and analyzed for progesterone, estrogen, and testosterone concentrations. Results showed significant differences in fecal pellet size between putative calves and adults for both sexes and populations–seasons. Progesterone concentration was significantly higher in Jasper–fall and North Interlake–winter adult females. Testosterone was significantly higher in Jasper–fall adult males. North Interlake–winter males exhibited no significant difference in hormone concentrations between age classes. When applied to the entire Jasper data set, 98% of females and 88% of males were assigned to an age class. This study illustrates the possibilities of using noninvasive methods to determine an age class in wild ungulate populations.

Impact of diet on faecal output and caecotroph consumption in rabbits.

To assess the impact of four rabbit diets (hay only, extruded diet with hay, muesli with hay and muesli only) on faecal pellet size, faecal output and caecotrophy. Thirty-two Dutch rabbits were studied over 17 months. Faecal pellet size and weight were measured in weeks 3, 9, 21 and 43 and faecal output in weeks 10, 22 and 45. Number of uneaten caecotrophs was recorded weekly. Faecal pellets were consistently smaller and lighter in rabbits fed muesli only, and the size of pellets produced by those fed muesli with hay decreased over the course of the study. Faecal output was greatest in rabbits with the highest hay intake. Uneaten caecotrophs were found in greatest frequency in rabbits fed muesli. Muesli diets have a negative effect on faecal output and caecotroph ingestion and may therefore predispose to digestive disorders. Higher hay intake is associated with greater faecal output and fewer uneaten caecotrophs and may assist in preventing the gastrointestinal stasis.

Optimization of Scat Detection Methods for a Social Ungulate, the Wild Pig, and Experimental Evaluation of Factors Affecting Detection of Scat.

Collection of scat samples is common in wildlife research, particularly for genetic capture-mark-recapture applications. Due to high degradation rates of genetic material in scat, large numbers of samples must be collected to generate robust estimates. Optimization of sampling approaches to account for taxa-specific patterns of scat deposition is, therefore, necessary to ensure sufficient sample collection. While scat collection methods have been widely studied in carnivores, research to maximize scat collection and noninvasive sampling efficiency for social ungulates is lacking. Further, environmental factors or scat morphology may influence detection of scat by observers. We contrasted performance of novel radial search protocols with existing adaptive cluster sampling protocols to quantify differences in observed amounts of wild pig (Sus scrofa) scat. We also evaluated the effects of environmental (percentage of vegetative ground cover and occurrence of rain immediately prior to sampling) and scat characteristics (fecal pellet size and number) on the detectability of scat by observers. We found that 15- and 20-m radial search protocols resulted in greater numbers of scats encountered than the previously used adaptive cluster sampling approach across habitat types, and that fecal pellet size, number of fecal pellets, percent vegetative ground cover, and recent rain events were significant predictors of scat detection. Our results suggest that use of a fixed-width radial search protocol may increase the number of scats detected for wild pigs, or other social ungulates, allowing more robust estimation of population metrics using noninvasive genetic sampling methods. Further, as fecal pellet size affected scat detection, juvenile or smaller-sized animals may be less detectable than adult or large animals, which could introduce bias into abundance estimates. Knowledge of relationships between environmental variables and scat detection may allow researchers to optimize sampling protocols to maximize utility of noninvasive sampling for wild pigs and other social ungulates.

Size as the master trait in modeled copepod fecal pellet carbon flux

AbstractZooplankton fecal pellet flux is a highly variable component of the biological carbon pump. While fecal pellets can comprise 0 to nearly 100% of particulate organic carbon collected in sediment traps, mechanisms for this variability remain poorly understood. Fecal pellet carbon flux is a complex function of several variables. We present a model that incorporates individual‐scale metabolic processes to determine fecal pellet production rate, the relationship between body size and fecal pellet size, the relationship between fecal pellet size and sinking rate, and a function representing the breakdown of particles in the water column. When applied to copepod communities sampled by the continuous plankton recorder in the Gulf of Maine over 25 years, a seasonal pattern of fecal pellet carbon flux emerges. The interannual flux time series produced by the model reflects known oceanographic perturbations and shows how organism‐scale processes can be scaled up to explain ecosystem level variability. We conclude that fecal pellet carbon flux in the Gulf of Maine is driven by copepod community size structure and copepod abundance, and that the fraction of fecal pellet carbon that reaches depth is a function of copepod size, rather than abundance. Changes in the physical environment which alter the size composition of the copepod community lead to variability in fecal pellet carbon flux. Our results indicate that incorporating size composition into biogeochemical models can more accurately constrain zooplankton‐mediated carbon flux.

A Non-Invasive Population Study of Moose in Northern Yellowstone National Park

North American moose (Alces alces) populations are declining across much of their southern distribution from the Canadian Maritimes to the Rocky Mountain range of the Shiras moose subspecies (Alces alces shirasi). Shiras moose population declines have been documented in Montana and Wyoming with reduced productivity reported from Utah and Colorado. These declines are due to a combination of factors including the natural succession, loss, and degradation of habitat; predation by wolves and bears; disease caused by infection from artery worm; and parasitism by moose ticks. The effects of heat stress may also contribute to chronic malnutrition and a reduction in female fertility. Significant reductions in Montana and Wyoming moose populations adjacent to Yellowstone National Park (YNP) are indicative of regional moose population declines and suggest that moose numbers may be decreasing in YNP as well. In the northern portion of YNP, also known as the Northern Range (NR), significant loss of riparian willow browse due to overgrazing by elk for decades and by bison more recently, the reduction of mature and old-growth conifer forests from the fires of 1988 and from disease more recently have reduced both winter habitat quality and quantity for moose. Several moose with cropped ears, an external sign of the disease Elaeophorosis, or artery worm, have been observed over the past few years on the NR suggesting that the disease may also be present in YNP. Northern Range estimates of moose have decreased from almost 400 in 1970 to possibly fewer than 100 today. Despite evidence suggesting moose decline in YNP, no current population data exists. Knowledge of population demographics serves as a critical baseline for evaluating and understanding factors leading to population declines. However, because moose are solitary, prefer densely vegetated habitats, and are present at low densities, collecting population data is challenging. Traditional methods of studying moose that require capture, radio-collaring, and aerial surveys are costly, sometimes produce unreliable results, can be harmful to the study animal, and are discouraged in some jurisdictions such as national parks. Non-invasive sampling, the collection of data without having to capture, handle, or in any manner physically restrain study animals, has proven to be a valuable tool for acquiring accurate population data from free-ranging ungulates when using traditional methods is neither feasible nor practical. In December 2013, we initiated a three-year non-invasive moose population study in YNP with the main objective to estimate population demographics of NR moose. For three consecutive winters we will be systematically collecting fecal pellets from the extent of NR moose wintering habitat. We are extracting DNA from epithelial cells on the pellet surface and through genetic testing will be able to identify individual moose and their genders. Female pellet samples will be analyzed for pregnancy hormone concentrations to make inferences on pregnancy rates. Because fecal pellet size is directly related to moose size, and therefore to moose age, we will use various pellet measurements to differentiate between age classes. These data will be used in capture-recapture modeling to estimate population abundance and vital rates.

Can molecular data validate morphometric identification of faecal pellets in Tanzanian forest antelope species?

Forest-dwelling antelope species are often difficult to detect during surveys due to their cryptic behaviour and densely vegetated habitats. Dung counts have traditionally been used to infer forest antelope abundance but genetic identification has shown that visual identification of ungulate dung to species is often unreliable. This study attempted to use easily obtained morphometric data from faecal pellets to statistically assign antelope dung piles to species. We measured pellets from 238 dung piles collected from the Udzungwa Mountains, south-central Tanzania, a largely forested landscape with five forest-associated antelope species including the endangered Abbott’s duiker Cephalophus spadix. The species identity of sampled dung piles was determined by amplifying a c. 600 bp fragment of the mitochondrial control region and aligning DNA sequences with published references. We found no diagnostic differences in faecal pellet size between antelope species although there were significant differences in mean pellet length and width. We employed a single variable linear discriminant analysis to predict the species of dung piles based on pellet length. Despite significant differentiation between species we obtained an overall accuracy of 58.8 % that did not meet our specified probability threshold (P < 0.05). Abbott’s duiker dung piles were correctly assigned in the majority of cases (74 %). Overall, morphometric assignment of dung piles to species was not accurate enough to validate dung counts as a survey method for forest antelope although our results do not preclude the development of alternative field identification methods using additional non-molecular characters.

Time series of vertical flux of zooplankton fecal pellets on the continental shelf of the western Antarctic Peninsula

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 471:23-36 (2012) - DOI: https://doi.org/10.3354/meps10021 Time series of vertical flux of zooplankton fecal pellets on the continental shelf of the western Antarctic Peninsula Miram R. Gleiber1,*, Deborah K. Steinberg1, Hugh W. Ducklow2 1Virginia Institute of Marine Science, Gloucester Point, Virginia 23062, USA 2The Ecosystems Center, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA *Email: mrglei@vims.edu ABSTRACT: Zooplankton fecal pellet contribution to particulate organic carbon (POC) flux over the continental shelf of the western Antarctic Peninsula (WAP) was investigated to better understand the possible effects of changes in zooplankton community structure, due to climate change, on carbon export. Fecal pellets were collected at 170 m depth in a moored sediment trap from January 2004 to January 2009. Fecal pellet shape and size (i.e., carbon content) were quantified to assess flux of pellets from different zooplankton taxa and compared between seasons and years. Fecal pellet POC constituted the dominant proportion of total POC flux, with summer (November to April) pellet POC flux (67%) significantly higher than winter (May to October) pellet POC flux (34%), while phytodetritus or fecal ‘fluff’ constituted the remainder. Cylindrical euphausiid pellets contributed to a monthly mean of 72% of total fecal pellet flux; ovoid copepod and tabular salp pellets contributed significantly less (22 and 6%, respectively). Cylindrical and ovoid pellet export was significantly higher in summer, while 48% of tabular pellet flux occurred in winter. Tabular pellets had the highest carbon content (median = 1.03 µgC pellet−1, highest 134.9 µgC pellet−1), followed by cylindrical (0.20 µgC pellet−1) and ovoid (0.04 µgC pellet−1) pellets. As krill fecal pellets are the dominant component of particle export in the WAP, we hypothesize that a decrease in krill and increase in salps in the region could alter the export of POC to the deep sea. KEY WORDS: Southern Ocean · Particle flux · Sediment trap · Krill · Salp · Copepod · Climate Full text in pdf format PreviousNextCite this article as: Gleiber MR, Steinberg DK, Ducklow HW (2012) Time series of vertical flux of zooplankton fecal pellets on the continental shelf of the western Antarctic Peninsula. Mar Ecol Prog Ser 471:23-36. https://doi.org/10.3354/meps10021 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 471. Online publication date: December 19, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

Contribution of zooplankton fecal pellets to deep ocean particle flux in the Sargasso Sea assessed using quantitative image analysis

Fecal pellet flux and size distribution at 500, 1500 and 3200 m depths were measured in sediment trap samples collected by the Oceanic Flux Program time-series off Bermuda, December 2006–November 2007. During the study, three mesoscale eddies passed through: a cyclonic eddy in bloom stage (February through mid-April), a decaying post-bloom mode-water eddy (late April through May), and an anticyclonic eddy (August through October). Variability associated with eddy passage masked any seasonal trends in flux or size distributions. At a depth of 1500 m, the fecal pellet flux ranged from a minimum of 100 pellets m−2 day−1 to a maximum of 500 pellets m−2 day−1 during the cyclonic eddy passage, corresponding to ranges in the fecal pellet mass and the carbon flux of 0.5–1.7 mg m−2 day−1 and 0.07–0.25 mg C m−2 day−1, respectively. Fecal pellets averaged 7 ± 3% of the organic carbon flux, a minimum estimate as disassociated pellets were not quantifiable. Size distribution shifts indicated small zooplankton and immature stages were more abundant within the cyclonic eddy, whereas larger zooplankton were present within the mode water and anticyclonic eddies. The fecal pellet number, flux and size distributions showed no consistent depth trends and indicated extensive fecal pellet reprocessing within the water column.

Use of faecal pellet size to differentiate age classes in female Svalbard reindeer Rangifer tarandus platyrhynchus

AbstractProper management of threatened populations requires prior knowledge of population sizes and structures, however, current techniques to gather this information are generally impractical, costly, and can be physically stressful for the animals. Non‐invasive methods (e.g. faecal sampling) that can produce high quality and accurate results are better alternatives. Using faecal samples collected from a Svalbard reindeer Rangifer tarandus platyrhynchus population in the winters of 2008 (N = 158) and 2009 (N = 161), we investigated and validated the feasibility of using faecal pellet sizes to differentiate between female calves, yearlings and adults. We found that pellets from adult females were longer than those from calves, and pellets from adults and yearlings were clearly wider than those from calves. With an accuracy of 91% correct classification, we did show that a combination of faecal pellet dimensions (length, width and depth), rather than a single dimension alone, can allow managers to clearly differentiate between age classes if pellets already identified as being from females are used. We also found a positive relationship between live weight and pellet size of the reindeer. Combined with DNA analysis to identify the gender of the animal that produced the faecal pellet, this information may provide important population parameters and be a valuable tool for the monitoring of various ungulate species including wild reindeer.

Biologically mediated sediment fluxes on coral reefs: sediment removal and off-reef transportation by the surgeonfish Ctenochaetus striatus

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 415:237-245 (2010) - DOI: https://doi.org/10.3354/meps08761 Biologically mediated sediment fluxes on coral reefs: sediment removal and off-reef transportation by the surgeonfish Ctenochaetus striatus Christopher H. R. Goatley*, David R. Bellwood Australian Research Council Centre of Excellence for Coral Reef Studies and School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia *Email: christopher.goatley@jcu.edu.au ABSTRACT: Off-reef sediment transport by the surgeonfish Ctenochaetus striatus (Acanthuridae) was quantified on the reef crest at Lizard Island, Great Barrier Reef. Three independent methods were implemented to estimate sediment ingestion rates. These considered (1) the bite rate and bite volume, (2) the defecation rate and faecal pellet size, and (3) the average gut contents and throughput rate. The 3 methods provided a broad range of estimates of sediment ingestion from 8.8 ± 2.4, to 66.1 ± 14.4 g fish–1 d–1 (mean ± SE). Nevertheless, these estimates were comparable to rates of sediment ingestion by parrotfishes (Labridae), the other major sediment-moving group on reefs. Overall, 36.5% of all sediment ingested was transported from the upper reef crest into deeper water, equating to a removal rate of 28.6 ± 6.2 kg 100 m–2 yr–1 at the study site. By brushing the reef, C. striatus reduces the sediment loading in the epilithic algal matrix (EAM) while causing little damage to the algal turf. Reducing sediments in EAMs provides favourable settlement surfaces for benthic organisms and increases the palatability of the EAM to herbivorous reef fishes, thus supporting reef resilience. The ecological importance of C. striatus, which is abundant on reefs throughout the Indo-Pacific, appears to have been underestimated, particularly when considering reef sediment dynamics. KEY WORDS: Ctenochaetus striatus · Sediment transport · Coral reef · Reef fish Full text in pdf format PreviousNextCite this article as: Goatley CHR, Bellwood DR (2010) Biologically mediated sediment fluxes on coral reefs: sediment removal and off-reef transportation by the surgeonfish Ctenochaetus striatus. Mar Ecol Prog Ser 415:237-245. https://doi.org/10.3354/meps08761 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 415. Online publication date: September 29, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.

Faecal pellet size can be used to differentiate age-classes in caribou: implications for non-invasive genetic studies

The inability to capture the age structure of a population using non-invasive faecal sampling has limited the scope of genetic analyses for wildlife research and conservation efforts. To overcome this, faecal morphometrics were examined to determine if differences exist between faeces size and the age of the individual producing it. Using faeces from known age caribou, pellet length distinguished calf and yearling age-classes from adult animals. Pellet width could only discern the calf age-class. Although this data is both area and species specific, gathering baseline data from known age animals prior to non-invasive collections may generate similar results and is recommended.

Evidence against the use of fecal pellet size for age determination in European wild rabbits

Techniques for estimating the age of wild animals are crucial to many aspects of the study of population biology. Accurate estimates of the proportion of different age classes in wild rabbit populations would be very useful, and the possibility that it could be obtained from the pellet size holds great appeal. However, this suggestion has created controversy in the literature as this technique has not been validated. This study involved assessment of whether threshold fecal pellet diameters could be used to differentiate adult and juvenile rabbits. The proportion of adults in four wild rabbit populations living in semi-natural conditions was compared with the proportion of animal pellets greater than threshold diameters of 6 mm and 4 mm. Our results suggest that inferring a relationship between the proportion of pellets >6 mm diameter and the proportion of adults in a population is not applicable to European wild rabbits, and that the use of this method could produce erroneous interpretations. The use of a 4 mm pellet diameter threshold appeared to produce even more inaccurate results. Studies that use this technique should include validation, as the results can vary greatly among individuals and populations.

Can adult and juvenile European rabbits be differentiated by their pellet sizes?

Recently, a new method for differentiating juvenile and adult rabbits based on faecal pellet size was published. According to this method, pellets >6 mm diameter are inferred to be deposited by adults, while those <6 mm are inferred to be from juveniles or kittens. In this study, we designed a simple experiment to test the accuracy of this methodology. Twelve adult rabbits were housed in individual outdoor cages and their pellets were removed every day for 10 consecutive days. Pellets were separated using a sieve according to their size and counted. Results showed that adult rabbits produce pellets >6 mm diameter in the same proportion as those <6 mm. We also observed a strong influence of the individual rabbit on pellet size; some rabbits produce a high proportion of pellets >6 mm, whereas others deposit mostly pellets <6 mm in size. Our findings demonstrate that pellet size is unsuitable for aging wild rabbits. Field biologists should therefore be cautious when employing the pellet size method of age determination in other wild animals in the absence of validating studies.