Increase In Overall Abundance Research Articles

An Increase in Prominent Probiotics Represents the Major Change in the Gut Microbiota in Morbidly Obese Female Patients upon Bariatric Surgery

The global increase in obesity carries inherent health implications, with an increased BMI being a known risk factor for diseases such as type 2 diabetes, cardiovascular diseases, or different cancer types. The long-term effectiveness of diet therapy in addressing morbid obesity is extremely limited, with no adequate pharmaceutical agents available as treatment options, resulting in bariatric surgery being the only viable option to achieve and maintain significant long-term weight loss. Something that plays an important role in overall human health is the gut microbiome and its complex composition, which is usually altered and reduced in complexity/diversity in severely obese patients. In this study, the influence of bariatric surgery and the resulting weight loss on the gut microbiome composition of twelve morbidly obese (BMI ≥ 40) adult female central European patients was investigated by comparing the relative abundances of the major microbial phyla Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria pre- and post-surgery. We also aimed to give insight into the major changes in individual prominent and promising future probiotic bacteria characterized by an overall increase in abundance accompanied by a switch of enterotypes. Identifying specific microbial alterations associated with successful weight-loss outcomes may contribute to the development of future therapeutic interventions by supplementation with next-generation probiotics.

Cross-Talk between Hematopoietic Cells and Fibroblast Subsets Drives Inflammation and Remodelling of the Bone Marrow Microenvironment in Myeloproliferative Neoplasms

Introduction: In a proportion of patients with myeloproliferative neoplasms (MPNs), severe remodelling of the bone marrow microenvironment develops, with myelofibrosis (MF) and osteosclerosis leading to cytopenias and poor survival. Mesenchymal stromal cells (MSCs) have been implicated in MF pathogenesis (Leimkühler, Cell Stem Cell, 2021), including Nestin+ (Arranz, Nature, 2014), Gli1+ (Schneider, Cell Stem Cell, 2017) and Leptin-receptor+ MSCs (Decker, Nat Cell Bio, 2017). However, little is known about the cellular subtypes and transcriptional states of fibroblast subtypes in MF, and the key receptor-ligand (R-L) interactions that lead to their activation. Our aim was to build a fully comprehensive atlas of MF bone marrow and clarify the pathological interactions between MPN cells and their stromal environment to determine the key drivers of inflammation and fibrosis. Methods: We performed single cell RNA sequencing of mononuclear cells, hematopoietic stem/progenitor cells (HSPCs), CD41+ cells and CD45- Lin- Ter119- CD71low/- stromal cells from MF (MPLW515L) mice and controls, as well as CD45- Lin- CD235ab- CD71low/- stromal cells from MPN patients. Targets were validated using a novel human bone marrow organoid platform(Khan et al, bioRxiv, 2022) and by analysis of bone marrow biopsies from MPN patients and controls. Results: More than 75,000 cells were analysed from control and MF mice, capturing 42,319 hematopoietic cells (including HSPCs, myeloid, lymphoid, megakaryocytes) and 34,969 stromal cells, including fibroblasts, MSCs, osteoblasts, chondrocytes, pericytes, arterial and sinusoidal endothelial cells (Fig.1A). Erythroid, neutrophil, megakaryocytes and also eosinophil-basophil-mast (EBM) cells were increased in abundance in MF mice, together with a ~4 - 8 fold expansion of MSCs and a more modest increase in overall abundance of fibroblasts. Extracellular matrix factors were expressed mainly by stromal cells (MSCs, fibroblasts) but also by EBM cells and neutrophils. As reported (Leimkühler, Cell Stem Cell, 2021), expression of hematopoiesis support factors by MSCs was reduced in MF. However, prior studies have not captured fibroblast subtypes. We found that the reduction in niche support from MSCs was compensated by a significant increase in hematopoiesis support factors from fibroblasts and EBM cells. Despite minimal increase in fibroblast cells overall, a subset of inflammatory fibroblasts (iFib) with high metabolic and glycolytic activity, TNFα signaling via NF-κB and TGFβ signaling was dramatically expanded in the MF mice, and also detectable in stromal cells from MPN patients. This atlas enabled detailed study of aberrant cross-talk between hematopoietic and stromal compartments. Overall, receptor-ligand (R-L) interactions were 20% higher in MF mice due to increased signaling from megakaryocytes, EBM, MSC and iFib cells, implicating these four cellular subsets as key mediators of pathogenic cross-talk. R-L interaction analyses predicted increased TNFα signaling (TNFRSF1A → TNF) from EBM to both MSC and iFib, and increased TGFβ signaling (TGFBR2 → TGFB1) between EBM and megakaryocytes to MSC and fibroblast subtypes, including iFib. The expanded subsets of megakaryocytes and EBM cells were noted to express notably high levels of galectins LGALS1 and LGALS3, encoding soluble β-galactoside-binding proteins associated with inflammation and tumorigenesis, and galectin signaling via predicted interacting partners was significantly increased in MF. High LGALS1 correlated with significantly shorter survival in patients with myeloid malignancies in the Cancer Genome Atlas myeloid leukemia cohort. Inhibition of galectin-1 with OTX008 significantly reduced TGFβ-induced collagen 1 and αSMA expression by human bone marrow stromal cells in 2D cultures as well as in human iPSC-derived bone marrow organoids, and bone marrow biopsies from a cohort of MF and non-fibrotic ET/PV patients showed a striking association of galectin-1 with fibrosis (Fig.1B). Conclusions: We present a roadmap of the cellular and molecular landscape of normal and myelofibrotic bone marrow. We identify two cellular subsets (EBM and iFib) whose role as mediators of the inflammatory microenvironment in MF was previously unappreciated, and propose galectin-1 as a novel biomarker and potential mediator of fibrosis. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Oral microbiota analyses of Saudi sickle cell anemics with dental caries

The objectives of this study were to identify the composition of oral microbiota in a cohort of patients with sickle cell anemia (SCA) and a high mean number of decayed, missing, and filled permanent teeth (DMFT) and compare it to a cohort of patients with SCA and a low number of DMFT and elucidate the effect of fetal haemoglobin levels on the oral microbiota composition. Patients who had been diagnosed with SCA, who were homozygous for sickling β-globin mutation (βS/βS), who had Arab-Indian haplotype, and who ranged in age from 5 to 12 years were included in this study. Oral saliva from each participant (n=100) was collected in GeneFiX™ Saliva DNA Microbiome Collection tube and DNA was extracted using GeneFiX™ DNA Isolation Kits. The composition of oral 16S rRNA from patients with SCA and high dental caries (n=27, DMFT ≥5) and low dental caries (n=73, DMFT ≤4) was analysed. Sequencing was performed on an Ion Personal Genome Machine using, Ion PGM Hi-Q view Sequencing 400-bp kit. We observed an overall increase in abundance of Proteobacteria, Chloroflexi, and Bacteroidetes in the high DMFT index group compared to those with a low DMFT index. In addition, there was an overall increased abundance of microbiota from Proteobacteria, Fusobacteria, Firmicutes, and Bacteroidetes in the patients with SCA with low fetal haemoglobin compared to those with high fetal haemoglobin (P < .05). Enterobacteriaceae species were the most significant abundant species of bacteria found in both the high DMFT index group and low fetal haemoglobin cohort (P < .05). Our data indicate that SCA in Saudi patients with high DMFT have a higher predominance of pathogenic bacteria compared to those with low DMFT. Furthermore, SCA in Saudi patients with low fetal haemoglobin have a higher predominance of pathogenic bacteria compared to those with higher fetal haemoglobin.

Larval lake whitefish distribution in the open waters of Green Bay, Lake Michigan

Most lake whitefish populations within Lake Michigan are experiencing widespread population declines due to low levels of recruitment. However, the stock within Green Bay is flourishing, and various assessment tools suggest consistent recruitment to the juvenile stage each year. The distribution of offshore and drifting lake whitefish larvae were last described in the 1970s, prior to the resurgence of the southern Green Bay stock and prior to increasing knowledge of adult spawning behavior. We conducted a Green Bay wide survey of lake whitefish larvae over three years to provide an update of larval abundance and distribution and to discern influential biotic and abiotic factors that correlate to larval densities. In contrast with historical studies, our sampling illustrated high densities of larvae in both offshore and nearshore environments. Offshore expansion may be a factor in the population increase, but long term survival effects are still unknown. This study also provides the first documentation of larvae within the southern end of the bay below Chambers Island, WI and near re-colonized rivers. Average overall densities were relatively consistent each year, ranging between 29.5 and 49.6 per 1000 m3. Lake whitefish larvae were patchy in distribution and were associated with warmer and more productive waters at small spatial scales. Larval lake whitefish appear to be distributed widely throughout the entirety of Green Bay during the drift life stage, and we discuss our results in light of re-established river spawning and the overall increase in abundance.

Growth of Greater White‐Fronted Goose Goslings Relates to Population Dynamics at Multiple Scales

ABSTRACTThe abundance of greater white‐fronted geese (Anser albifrons frontalis) on the Arctic Coastal Plain (ACP) of northern Alaska, USA, has more than tripled since the late 1990s; however, recent rate of annual population growth has declined as population size increased, which may indicate white‐fronted geese on the ACP are approaching carrying capacity. We examined rates of gosling growth in greater white‐fronted geese at 3 sites on the ACP during 2012–2014 to assist with predictions of future population trends and assess evidence for density‐dependent constraints on recruitment. We marked goslings at hatch with individually coded webtags and conducted brood drives during early August to capture, measure, and weigh goslings. Annual estimates of gosling mass at 32 days old (range = 1,190–1,685) indicate that goslings had obtained &gt;60% of asymptotic size. This rate of growth corresponds with that of other goose species and populations with access to high‐quality forage and no limitations on forage availability, and is consistent with the overall increase in abundance of white‐fronted geese at the ACP scale. Contrary to most previous investigations, age‐adjusted mass of goslings did not decline with hatch date. Goslings grew faster in coastal areas than at inland freshwater sites. Taken together, these findings suggest forage was not limiting gosling growth rates in either ecosystem, but forage was of greater quality in coastal areas where goose foraging habitat is expanding because of permafrost subsidence. Spatial patterns of gosling growth corresponded with local‐scale patterns of population density and population change; the areas with greatest rates of gosling growth were those with the greatest population density and rates of population increase. We found little evidence to suggest forage during brood rearing was limiting population increase of white‐fronted geese on the ACP. Factors responsible for the apparent slowing of ACP‐wide population growth are likely those that occur in stages of the annual cycle outside of the breeding grounds. Published 2021. This article is a U.S. Government work and is in the public domain in the USA.

Recovery, conservation status, and environmental effects on arapaima populations in Guyana

Abstract Using population estimates that were made regularly between 2001 and 2013, the state of recovery of arapaima populations and their IUCN conservation status were assessed after they were almost extirpated from the upper Essequibo basin, Guyana. Recovery rates were compared across multiple areas with different degrees of access by fishers to evaluate effectiveness of conservation efforts. Population estimates were also used to investigate the influence of environmental factors on arapaima abundance in lakes with different morphometries, vegetation, and water types and to determine the relationship between the numbers of spawning individuals and subsequent recruits (at about age 2 years). The most recent census conducted in November–December of 2013 indicated a 5.6‐fold increase in overall abundance compared with 2001, with 4,591 individuals, of which 1,932 were juveniles (1.0–1.5 m total length) and 2,659 adults. Assessment of conservation status following IUCN criteria indicated that arapaima populations in the upper Essequibo basin in 2001 would have been considered borderline Critically Endangered, but in 2013 after conservation interventions, status would be categorized as Near Threatened. Arapaima in the Essequibo basin appear to favour larger but shallow lakes with low conductivity, clear water, and abundant aquatic macrophytes. Stock–recruitment relationships suggest that the entire upper Essequibo basin population may still be growing and that there is approximately a 1:1 juvenile to adult ratio. This ratio of juveniles to adults across all areas suggests a paucity of young fishes to sustain overall population growth, which might reflect widespread illegal removals of young fishes in the basin. Comparisons of arapaima densities in the upper Essequibo basin with those at four localities across the Amazon Basin, suggest that with enhanced conservation efforts in the Essequibo, populations could potentially increase two‐fold or more.

Initial butyrate producers during infant gut microbiota development are endospore formers.

The acquisition of the infant gut microbiota is key to establishing a host-microbiota symbiosis. Microbially produced metabolites tightly interact with the immune system, and the fermentation-derived short-chain fatty acid butyrate is considered an important mediator linked to chronic diseases later in life. The intestinal butyrate-forming bacterial population is taxonomically and functionally diverse and includes endospore formers with high transmission potential. Succession, and contribution of butyrate-producing taxa during infant gut microbiota development have been little investigated. We determined the abundance of major butyrate-forming groups and fermentation metabolites in faeces, isolated, cultivated and characterized the heat-resistant cell population, which included endospores, and compared butyrate formation efficiency of representative taxa in batch cultures. The endospore community contributed about 0.001% to total cells, and was mainly composed of the pioneer butyrate-producing Clostridium sensu stricto. We observed an increase in abundance of Faecalibacterium prausnitzii, butyrate-producing Lachnospiraceae and faecal butyrate levels with age that is likely explained by higher butyrate production capacity of contributing taxa compared with Clostridium sensu stricto. Our data suggest that a successional arrangement and an overall increase in abundance of butyrate forming populations occur during the first year of life, which is associated with an increase of intestinal butyrate formation capacity.

Dispersion of vendace eggs and larvae around potential nursery areas reveals their reproductive strategy

Abstract Depending on their reproductive strategy, different fish species aim to aggregate or disperse eggs and larvae in their reproductive habitat. Many pelagic species disperse their eggs widely around the potential nursery areas. Larval dispersion or aggregation affects population sub‐structuring, which has important implications in fisheries management and conservation of the natural spatial diversity in populations. The dispersion of larval vendace (Coregonus albula) was quantified in two oligotrophic Finnish lakes, and effects of density and environmental variables on the inter‐annual variation in the larval distribution were examined by analysing spatial abundance data from the lakes from 1999 to 2017. A 3‐D hydrodynamic egg distribution model was used to simulate the larval transport after hatching. Vendace larvae dispersed lake‐wide to both littoral and pelagic zones but, in some littoral hot spots, more larvae aggregated year after year. However, in years of high larval number, the densities increased not only in the hot spots, but generally at all sampling plots. An overall increase in abundance was observed at all sampling sites. The simulations of the egg distribution model supported the hypothesis that the dispersion of the eggs occurs by spawners, i.e. by spawning at several different spawning sites, which are located all around the lake. The dispersion of vendace eggs and larvae can be seen as a bet‐hedging strategy in space and time since in boreal oligotrophic large lakes with fragmented morphology, weather and other environmental factors in spring during hatching varies from year to year spatially in unpredictable manner. Lake‐wide larval dispersion suggests that the subpopulations of adjacent lake deeps may swap considerable amounts of individuals during early life and may not be closed units. Conservation of particular habitats seems unnecessary for Finnish vendace populations where large potential spawning areas in lakes are available.

Benthic foraminiferal response to the removal of aquaculture fish cages in the Gulf of Aqaba-Eilat, Red Sea

Abstract For about 20 years, finfish were reared in floating cages at the northern end of the Gulf of Aqaba-Eilat, Red Sea. The benthic ecosystem at the fish cages area was severely impacted by organic enrichment, resulting in an environment with no living foraminifera. A government decision led to the fish cages' removal in June 2008, creating a unique opportunity to monitor and assess post-removal changes in the benthos. Three years of benthic foraminiferal assemblage monitoring, beginning in July 2008 and ending in July 2011, are summarized here. Monitoring was carried out monthly by collecting sediment samples from stations of varying distances from the fish farm location, and, after its appearance in the summer of 2009, sampling the native seagrass Halophila stipulacea. Living foraminifera first appeared in the sediment in January 2009, progressively increasing in abundance thereafter. A clear difference in the rate of the rehabilitation process was observed on a spatial scale, related to distance from the point source of the organic enrichment. Recovery began with the first appearances of a few living individuals of Ammonia spp., Amphistegina lessonii and Nonion spp. By July 2009, a significant increase in overall abundance was recorded in the stations furthest from the fish cages, with Operculina ammonoides strongly dominating the assemblages. Populations of O. ammonoides revealed polymorphism in the coiling mode of their shells. Inflated involute and semi-involute forms dominate the living assemblages, whereas flattened evolute tests are more common in the dead assemblages, representing the period that preceded the fish farms. Unlike previous interpretations in the literature, in which such morphological variation was attributed to hydrodynamic energy or depth habitats, here it is hypothesized that the inflated involute and semi-involute forms are a morphological trait characteristic of the pioneer assemblages colonizing the area after its recovery from fish cages eutrophication. The reestablishment of the native H. stipulacea seagrass community was an important factor enabling epiphytic foraminifera to colonize the previously impacted sediments. All living foraminiferal species found on the seagrasses were also found in the former assemblages, suggesting that seagrass meadows existed before eutrophication and were the main habitats of the dead assemblages.

Long-term increases in abundance of anemonefish and their host sea anemones in an Australian marine protected area

Understanding the population dynamics of host sea anemones and their symbiotic anemonefish is important given that pressures such as aquarium collecting and bleaching events are adversely impacting their abundance in some Indo–Pacific locations. We examined long-term trends in anemone and anemonefish abundance at four sites within a ‘no-take’ zone at North Solitary Island, Australia, by comparing data from 2008 to surveys done in 1994 and 1995. Species richness was stable, comprising two anemones, Entacmaea quadricolor and Heteractis crispa, and three anemonefishes, Amphiprion akindynos, A. latezonatus, and A. melanopus. In 2008, densities of the most abundant species, E. quadricolor and A. akindynos, were substantially higher than previously recorded, with increases of up to 532% and 133%, respectively. There was a strong relationship between A. akindynos densities and anemone cover, whereas A. latezonatus had higher densities in deeper waters. Densities of this species remained similar over time, although there was a decline at one site. Heteractis crispa and A. melanopus were found in comparatively low numbers. Potential reasons for the overall increase in abundance include: protection from severe swell events, the lack of major bleaching events, the ability of E. quadricolor to reproduce rapidly by asexual reproduction, and the increasing duration of marine park protection.

Long-term response of Dreissena polymorpha larvae to physical and biological forcing in a shallow lake

Müggelsee, a shallow eutrophic lake (Berlin, Germany), has been subject to global warming and concurrent reductions of anthropogenic nutrient loading during the past decades. Here, we focus on the recent increase in abundance of Dreissena polymorpha larvae. We aimed at ascertaining whether the change in abundance of larvae was driven by changes in climate, especially by climate warming, and/or by the concurrent changes in trophic state of the lake. Both the numbers of small, newly developed larvae and their lengths have increased in recent years, suggesting that conditions for overall reproductive success have improved. The timing of the increase in abundance of larvae was matched by changes in nutrient loading and phytoplankton biomass, induced by a reduced inflow of nutrients into the lake. Besides a correlation between the first appearance of larvae each year and the timing of the requisite temperature for first spawning (12 degrees C), no relationship between changes in water temperature and abundance, length and survival rates of larvae was found. However, a sudden drop in abundance of larvae in 2003 may be primarily attributed to low dissolved oxygen conditions during an unusually long period of stratification, induced by anomalous meteorological conditions. The increase in length and survival rates of larvae was most likely due to changes in food composition, which followed the decrease in nutrient availability, and to changes in the occurrence of planktivorous fish. The results suggest that the first appearance of larvae per year and the decline in abundance of larvae in 2003 were driven by climatic influences, while the overall increase in abundance and length of D. polymorpha larvae in Müggelsee was more likely caused by changes in the trophic state of the lake rather than by climate warming.

Regional record of a global oceanic anoxic event: OAE1a on the Apulia Platform margin, Gargano Promontory, southern Italy

The Gargano Promontory of southern Italy, located on the eastern margin of the Apulia Platform, represents a peculiar Tethyan area where the transition between carbonate platform and adjacent basins is exposed on land. The Aptian stratigraphic record, represented in shallow-water, slope and deep-water deposits, provides a good opportunity to investigate the regional response to the worldwide documented climatic, biotic and palaeoceanographic changes related to Oceanic Anoxic Event 1a (OAE1a). A synthesis of data previously published (Ischitella and Coppitella sections), together with original data (Val Carbonara and Coppa della Guardia sections), from four stratigraphic sections from different depositional settings (proximal to distal) is provided, using an integrated, high-resolution micropalaeontological (planktonic foraminifera and calcareous nannofossils) and, for one section, geochemical (stable carbon and oxygen isotopes) approach. Organic matter preservation is confined to the more distal areas and consists of two thin intervals of black shales in the Aptian portion of the Marne a Fucoidi Formation. Biostratigraphic data assign the older black shale (5 cm thick) to the Selli Level equivalent (OAE1a, Lower Aptian); this carbon-rich interval is immediately followed by another black shale (7–10 cm thick) of early Late Aptian age. OAE1a is generally interpreted as a high-productivity event during a warming interval, followed by a cooling trend. In the Gargano Promontory, although the oxygen isotope curve indicates the above-mentioned climatic evolution, the micropalaeontological data do not support high fertility of the surface water, whereas micropalaeontological and geochemical data for the younger black shale do record high productivity (radiolarian increase in overall abundance, low nannofossil and foraminiferal species richness, increase in abudance of nannofossil fertility indices) associated with a cooling trend. The carbon and oxygen isotope record is in line with evidence from the curves documented elsewhere, whereas, among the biotic events, only the “nannoconid crisis” preceding OAE1a is revealed to be globally correlable. Environmental models for the two episodes of organic matter preservation are proposed, taking into account both global and local controlling factors.

Fishes associated with artificial reefs: attributing changes to attraction or production using novel approaches

Two widely‐recognized hypotheses propose that increases in fish abundance at artificial reefs are caused by (a) the attraction and redistribution of existing individuals, with no net increase in overall abundance and (b) the addition of new individuals by production, leading to a net increase in overall abundance. Inappropriate experimental designs have prevented many studies from discriminating between the two processes. Eight of 11 experiments comparing fish abundances on artificial reefs with those on adjacent soft bottom habitats were compromised by a lack of replication or spatial interspersion in the design itself. Only three studies featured proper controls and replicated designs with the interspersion of reef and control sites. Goodness of fit tests of abundance data for 67 species from these studies indicated that more fishes occur on reefs than on controls, particularly for species that typically occur over hard substrata. Conversely, seagrass specialists favour controls over reefs. Changes in the appearance of fish abundance trajectories driven by manipulation of sampling intervals highlight the need for adequate temporal sampling to encompass key life history events, particularly juvenile settlement. To ultimately determine whether attraction and production is responsible for increased abundances on reefs, requires two experimental features: 1) control sites, both interspersed among artificial reefs and at reef and non‐reef locations outside the test area and 2) incorporation of fish age and length data over time. Techniques such as otolith microchemistry, telemetry and stable isotope analysis can be used to help resolve feeding and movement mechanisms driving attraction and production.

Empty habitat in coastal sediments for populations of macrozoobenthos

Species with wide dispersal are expected to have little empty habitat. This was tested by analysing habitat use in the Wadden Sea near the island of Sylt (North Sea). Sampling covered 222 intertidal sites spread across the Konigshafen tidal flats (4.5 km2, mapping approach conducted once) and 270 subtidal sites along 12 km of a tidal channel system (stratified random sampling in spring and autumn). For any single species, 'suitable habitat' was extrapolated from the ranges of water depth and sediment composition present at the ten sites with the highest frequency or abundance of the species. On average, macrobenthic species actually used less than half of the suitable sites within the scale of local populations; this was far less than expected from a lognormal distribution. In the subtidal, abundance of most species changed between the two sampling seasons. A 50% increase in overall abundance was accompanied by a decrease in empty habitat of only about 25%. Thus, a doubling of abundances would not fill the empty space but just of half of it. The polychaete Scoloplos armiger was an exception in occupying almost all of its suitable habitat in the intertidal and subtidal sediments. A distinct patch of high species richness occurred where flood waters persistently form a large gyre which may enhance larval settlement. We suggest that limitations to larval settlement and/or juvenile survival primarily cause the extent of the observed habitat emptiness.

The effects of NPK fertilization for nine years on boreal forest vegetation in northwestern Canada

Abstract. Plant productivity is limited by mineral nutrient availability in many boreal forest ecosystems. This study is an analysis of the growth responses of components of a boreal plant community (cryptogams, herbaceous and woody perennials, the dominant shrubs Salix glauca (grey willow) and Betula glandulosa (bog birch) and the dominant tree Picea glauca (white spruce), to the addition of an NPK fertilizer over a nine‐year period. The study was carried out in a low‐nutrient boreal forest ecosystem in the Yukon territory in northwestern Canada. The following predictions were tested: (1) that there would be an overall increase in abundance (measured either as cover, density, or dry mass) of all components of the vegetation, (2) that vegetation composition would change as more competitive species increased in abundance and (3) that initial community changes in response to fertilization would be transient. In general, all predictions were found to be true. Species composition changed rapidly in response to fertilizer. Graminoids (e.g. Festuca altaica) and some dicots (e.g. Mertensia paniculata and Achillea millefolium) increased in cover, while other dicots (e.g. Anemone parviflora), dwarf shrubs (e.g. Arctostaphylos uvaursi), bryophytes and lichens declined. There was a significant increase in the growth rate of the two dominant shrubs and of Picea, but not in the cone crop or seed production by Picea. Surveys after 1 or 2 years showed responses by the vegetation but more stable patterns of response did not emerge until after 5 or 6 years. There were consistent and directional changes in the percent cover of some of the herbaceous species on control plots. Growth rates of Salix and Betula varied considerably from year to year, independently of treatment. Long‐term studies are essential if we are to understand the role of nutrient limitation in this ecosystem.

Elevational zonation of mammals in the central Philippines

ABSTRACTTrapping and netting of small mammals on a land-bridge island (Leyte) and on an oceanic island (Negros) revealed similar patterns of elevational change in abundance and species richness. Fruit bats (Pteropodidae) reached their greatest local densities in agricultural areas, and were least abundant in montane mossy forest. The fruit bats found to be common in agri-cultural areas are widespread in Southeast Asia: in contrast, species that were most common in forested areas are Philippine endemics. Fruit bat abundance was greater on the oceanic island than on the land-bridge island. Trappable small mammals (families Soricidae and Muridae) showed no change in species richness with increasing elevation, but did show a gradual increase in overall abundance. Even though the oceanic island was depauperate of non-volant mammal species, it had the higher abundance of non-volant mammal individuals; however, this may have been due primarily to differences associated with the elevation of sampling sites. Murid rodents at the higher elevations on Leyte tend to be those that are members of the old endemic group of Philippine murids, and those at lower elevations tend to be members of more recently arrived groups. Most non-volant small mammals at all elevations on the oceanic Negros, and in agri-cultural areas on Leyte, are non-native species.

Paleoecology and biostratinomy of solitary rugose corals in the Stony Mountain Formation (Upper Ordovician), Stony Mountain, Manitoba

The four species of solitary Rugosa known from the Stony Mountain Formation at Stony Mountain in southern Manitoba belong to different genera, and differ from one another in external form. The distribution and abundance of taxa and their frequency with respect to one another were related to the degree of environmental restriction. The boundary between the Gunn Member and overlying Penitentiary Member corresponds to a marked increase in overall abundance and change in relative frequency. Helicelasma and Bighornia are dominant in the Gunn and lower Penitentiary, respectively. Deiracorallium and Lobocorallium decrease in frequency at the boundary.Larvae of these solitary Rugosa attached to the substrate with their cardinal side. Coralla of Helicelasma, Deiracorallium, and Lobocorallium were oriented in the sediment with the top of the convex cardinal side at or near the substrate surface and the upper part of the concave counter side exposed above it during life. Bighornia lay with the convex counter side in the sediment and the concave cardinal side at least partly exposed. Epizoic bryozoans generally became associated with live hosts, and were especially common on the exposed side of relatively large individuals. Microscopic boring algae infested the outer wall of most corals in the Gunn Member, usually while the hosts were alive. Responses of the polyp to stress and injury are indicated by redirection of the growth axis, constriction of the calice rim, and repair of broken calice rims. The attitudinal and directional orientations of solitary corals suggest that most and possibly all were transported after death. Differences in depositional orientation among the taxa are related to coral form. Currents were unidirectional from the present southeast during Gunn time, and either unidirectional from the southeast or northwest, or oscillating from both directions in early Penitentiary time. Abrasion of coral exteriors was primarily a post-mortem event associated with transportation. Trypanites borings were probably produced by one species of annelid after deposition of the corals. The degree of abrasion and frequency of annelid borings tended to increase with coral size and the duration of exposure before burial.