| 1. |
- Clements, Kendall, et al.
(författare)
-
Clostridia dominate 16S rRNA gene libraries prepared from the hindgut of temperate marine herbivorous fishes
- 2007
-
Ingår i: Marine Biology. - : Springer. - 0025-3162. ; 150:6, s. 1431-1440
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract Bacterial diversity in the microbial communities of posterior gut sections of three temperate marine herbivorous fish species from New Zealand was characterised using Amplified Ribosomal DNA Restriction Analysis, and 16S rRNA gene amplification and sequencing methods. The fish were collected in 1999–2000 in the Hauraki Gulf, New Zealand (35°54’–36°24’S, 174°48’–175°25’E). The gastrointestinal bacterial communities of Kyphosus sydneyanus (Günther, 1886) (F. Kyphosidae), Odax pullus (Forster in Bloch and Schneider, 1801) (F. Labridae) and Aplodactylus arctidens Richardson, 1839 (F. Aplodactylidae) were dominated by five clades of bacteria, four of which belong to recognized clostridial clusters. The clone libraries of K. sydneyanus and O. pullus contained sequences from most of these clades, but were dominated by members of clostridial clusters XI and XIVa, respectively. The clone library of A. arctidens was dominated by members of clostridial cluster XIVb and an unassigned cluster containing Eubacterium desmolans and Papillibacter cinnaminovorans. The finding that strains of Firmicutes dominated the gastrointestinal microbial communities of all three fish species is consistent with the results of similar studies on terrestrial vertebrate herbivores. This work thus contributes to the view that gastrointestinal symbionts in some marine herbivorous fishes may play a similar role to those in terrestrial vertebrate herbivores studied to date
|
|
| 2. |
- Donis, Daphne, et al.
(författare)
-
Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer
- 2021
-
Ingår i: Limnology and Oceanography. - : John Wiley & Sons. - 0024-3590 .- 1939-5590. ; 66:12, s. 4314-4333
-
Tidskriftsartikel (refereegranskat)abstract
- To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L-1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4 degrees C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.
|
|
| 3. |
- Lloyd-Price, Jason, et al.
(författare)
-
Multi-omics of the gut microbial ecosystem in inflammatory bowel diseases
- 2019
-
Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 569:7758, s. 655-661
-
Tidskriftsartikel (refereegranskat)abstract
- Inflammatory bowel diseases, which include Crohn's disease and ulcerative colitis, affect several million individuals worldwide. Crohn's disease and ulcerative colitis are complex diseases that are heterogeneous at the clinical, immunological, molecular, genetic, and microbial levels. Individual contributing factors have been the focus of extensive research. As part of the Integrative Human Microbiome Project (HMP2 or iHMP), we followed 132 subjects for one year each to generate integrated longitudinal molecular profiles of host and microbial activity during disease (up to 24 time points each; in total 2,965 stool, biopsy, and blood specimens). Here we present the results, which provide a comprehensive view of functional dysbiosis in the gut microbiome during inflammatory bowel disease activity. We demonstrate a characteristic increase in facultative anaerobes at the expense of obligate anaerobes, as well as molecular disruptions in microbial transcription (for example, among clostridia), metabolite pools (acylcarnitines, bile acids, and short-chain fatty acids), and levels of antibodies in host serum. Periods of disease activity were also marked by increases in temporal variability, with characteristic taxonomic, functional, and biochemical shifts. Finally, integrative analysis identified microbial, biochemical, and host factors central to this dysregulation. The study's infrastructure resources, results, and data, which are available through the Inflammatory Bowel Disease Multi'omics Database (http://ibdmdb.org), provide the most comprehensive description to date of host and microbial activities in inflammatory bowel diseases.
|
|
| 4. |
- Mantzouki, Evanthia, et al.
(författare)
-
Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins
- 2018
-
Ingår i: Toxins. - : MDPI. - 2072-6651. ; 10:4
-
Tidskriftsartikel (refereegranskat)abstract
- Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.
|
|
| 5. |
- Meyer, S., et al.
(författare)
-
On the edge of death: Rates of decline and lower thresholds of biochemical condition in food-deprived fish larvae and juveniles
- 2012
-
Ingår i: Journal of Marine Systems. - : Elsevier BV. - 0924-7963. ; 93, s. 11-24
-
Tidskriftsartikel (refereegranskat)abstract
- Gaining reliable estimates of how long fish early life stages can survive without feeding and how starvation rate and time until death are influenced by body size, temperature and species is critical to understanding processes controlling mortality in the sea. The present study is an across-species analysis of starvation-induced changes in biochemical condition in early life stages of nine marine and freshwater fishes. Data were compiled on changes in body size (dry weight, DW) and biochemical condition (standardized RNA-DNA ratio, sRD) throughout the course of starvation of yolk-sac and feeding larvae and juveniles in the laboratory. In all cases, the mean biochemical condition of groups decreased exponentially with starvation time, regardless of initial condition and endogenous yolk reserves. A starvation rate for individuals was estimated from discrete 75th percentiles of sampled populations versus time (degree-days, Dd). The 10th percentile of sRD successfully approximated the lowest, life-stage-specific biochemical condition (the edge of death). Temperature could explain 59% of the variability in time to death whereas DW had no effect. Species and life-stage-specific differences in starvation parameters suggest selective adaptation to food deprivation. Previously published, interspecific functions predicting the relationship between growth rate and sRD in feeding fish larvae do not apply to individuals experiencing prolonged food deprivation. Starvation rate, edge of death, and time to death are viable proxies for the physiological processes under food deprivation of individual fish pre-recruits in the laboratory and provide useful metrics for research on the role of starvation in the sea. (C) 2011 Elsevier B.V. All rights reserved.
|
|
| 6. |
- Moran, Damian
(författare)
-
Carbon dioxide degassing in fresh and saline water. II: Degassing performance of an air-lift
- 2010
-
Ingår i: Aquacultural Engineering. - : Elsevier BV. - 1873-5614 .- 0144-8609. ; 43:3, s. 120-127
-
Tidskriftsartikel (refereegranskat)abstract
- A study was undertaken to measure the efficiency with which carbon dioxide was stripped from freshwater (0 parts per thousand) and saline water (35 parts per thousand NaCl) passing through an air-lift at 15 degrees C. The air-lift was constructed of 50 mm (OD) PVC pipe submerged 95 cm in a tank, had an adjustable air injection rate, and could be adjusted to three lifting heights: 11,16 and 25 cm. The gas to liquid ratio (G:L) was high (similar to 1.9-2.0) at low water discharge rates (Q(w)) and represented the initial input energy required to raise the water up the vertical riser section to the discharge pipe. The air-lift increased in pumping efficiency rapidly thereafter, to a G:L minima of 0.3-0.6 at 60-70 L min(-1). After this point the G:L ratio increased with Q(w), representing decreasing air-lift pumping efficiency. The CO2 concentration of the influent and effluent water was measured using submersible infrared CO2 probes over a range of influent CO2 concentrations. The CO2 mass transfer coefficient [(k(L)a)(20)] ranged from 0.025 to 0.468. Increasing lift height increased mass transfer, which was attributed to both the increased G:L ratio and the contact time inside the air-lift. The relative effect of lift height and pumping rate on mass transfer was such that a 5 cm increase in lift height was approximately equal to a G:L increase of 0.5. The CO2 stripping efficiency was effectively the same between salinities, and the influent CO2 concentration only had a modest effect on CO2 stripping efficiency. At an influent concentration of 40 mg L-1 the CO2 stripping efficiency was 1-3% higher than at an influent of 10 mg L-1. The relatively minor effects of salinity and influent CO2 concentration on stripping efficiency contrasted with a companion study investigating the stripping efficiency of a cascade column. The difference was attributed to the low-to-moderate mass transfer efficiencies of the air-lift. A general equation was derived for the airlift that allows one to calculate the mass transfer coefficient for a given lift height, Q(w), or G:L ratio. The mass transfer coefficient can then be used to calculate the CO2 stripping efficiency for any water type (i.e. temperature, alkalinity, salinity and influent CO2 concentration). (C) 2010 Elsevier By. All rights reserved.
|
|
| 7. |
- Moran, Damian, et al.
(författare)
-
Chronic CO2 exposure markedly increases the incidence of cataracts in juvenile Atlantic cod Gadus morhua L.
- 2012
-
Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486. ; 364, s. 212-216
-
Tidskriftsartikel (refereegranskat)abstract
- A study was undertaken to test the affect of chronic exposure to elevated dissolved carbon dioxide on juvenile Atlantic cod. The CO2 treatment concentrations were designated as low (1-2 mg L-1, 1000 mu atm), medium (8 mg L-1, 3500 mu atm) and high (18 mg L-1, 8500 mu atm), and the fish were reared at 10 C and 20% salinity. A marked observation at the end of the 55 day trial was that an increase in the incidence of eye lesions correlated with increasing CO2 concentration. Typical lesions included unilateral and bilateral exopthalmos, gas bubbles under the sclera and cataracts, and these were quantified in all fish (n = 757 individuals) using field methods. The most notable difference between CO2 treatments was the prevalence and intensity of lenticular cataracts, which were primarily diffuse rather than nucleated. Nearly 75% of all fish from the high CO2 treatment were found to have some degree of cataractous lesion, compared with 10-13% for the other treatments. The severity of the cataract was most pronounced at the highest CO2 concentration, with many fish presenting complete bilateral cataracts. These data indicate that chronic exposure to high CO2 concentrations can cause cataracts in juvenile Atlantic cod. To our knowledge this is the first report of CO2 as a causative agent or aggravating factor for cataracts. (C) 2012 Elsevier B.V. All rights reserved.
|
|
| 8. |
- Moran, Damian, et al.
(författare)
-
Eyeless mexican cavefish save energy by eliminating the circadian rhythm in metabolism.
- 2014
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:9
-
Tidskriftsartikel (refereegranskat)abstract
- The eyed surface form and eyeless cave form of the Mexican tetra Astyanax mexicanus experience stark differences in the daily periodicities of light, food and predation, factors which are likely to have a profound influence on metabolism. We measured the metabolic rate of Pachón cave and surface fish at a fixed swimming speed under light/dark and constant dark photoperiods. In constant darkness surface forms exhibited a circadian rhythm in metabolism with an increase in oxygen demand during the subjective daytime, whereas cave forms did not. The lack of circadian rhythm in metabolism leads to a 27% energy savings for Pachón cave fish compared to surface fish when comparing both forms in their natural photoperiods. When surface forms were tested under constant dark conditions they expended 38% more energy than cave forms under equivalent conditions. Elimination of the circadian rhythm in metabolism may be a general feature of animals that live in perpetually dark food-limited environments such as caves or the deep sea.
|
|
| 9. |
- Moran, Damian, et al.
(författare)
-
Mortality structures population size characteristics of juvenile yellowtail kingfish Seriola lalandi reared at different densities
- 2011
-
Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7782 .- 1864-7790. ; 11:3, s. 229-238
-
Tidskriftsartikel (refereegranskat)abstract
- A study was undertaken to measure the effects of conspecific density on the growth, mortality and deformity rate of yellowtail kingfish Seriola lalandi Valenciennes during the first feeding period. Newly hatched larvae were stocked in replicate tanks at initial densities of 40, 60 and 100 ind. l(-1) until 30 d post-hatch (DPH). Live prey was administered at frequent intervals in an effort to maintain absolute prey density for all treatments. There was a negative relationship between conspecific density and mean individual length during the first half of the trial, which was attributed to food depletion between supplementary feedings at higher conspecific densities. The effect size (partial eta-squared) of conspecific density decreased considerably during the trial, to the point where the initial stocking density had no discernible effect on cohort growth or mortality rate. The apparent morphological deformity rate ranged from 17 to 32%, but did not differ between treatments. Jaw malformations were the most commonly observed deformity (12 to 30%). The weights of juveniles at the end of the trial were log-normally distributed, with some disproportionately large individuals skewing the weight distributions. There was substantial variation in mortality between and within treatments (74 to 97%), and the conspecific densities of each replicate at 30 DPH did not reflect the relative ordering of the initial treatments. Median individual weight was highly correlated with mortality and weight variance, and the positive skewness of populations decreased as mortality increased. Both trends indicated a strong population size-structuring mechanism. Given the controlled experimental conditions the size-structuring mechanism was not predation or cannibalism. Differential feeding success and an unidentified size-specific mortality agent are hypothesized to be the mechanisms by which mortality was able to strongly influence population size distributions.
|
|
| 10. |
- Moran, Damian
(författare)
-
Sampling effort required to obtain repeatable average size estimates of juvenile fish
- 2011
-
Ingår i: Aquatic Biology. - : Inter-Research Science Center. - 1864-7782 .- 1864-7790. ; 11:3, s. 239-242
-
Tidskriftsartikel (refereegranskat)abstract
- Larval and juvenile fish cohorts often have skewed size distributions due to inter-individual variation in growth rates. A resampling analysis was used to investigate how much sampling effort is required to achieve repeatable average size estimates in populations of juvenile yellowtail kingfish Seriola lalandi Valenciennes. One hundred juveniles (30 d post-hatch) were measured for total length and wet weight from 9 cohorts reared in captivity. From an analysis of cohort size distribution the mean was determined to be a suitable measure of the average for length, while the median was best for weight. One thousand resamples of mean length and median weight were performed for each cohort data set, with sample sizes ranging from 2 to 100 individuals. The point at which increasing sample size resulted in only a negligible increase in precision (variance between resamples <0.1%) corresponded to n = 19 for mean length and n = 30 for median weight. Since yellowtail kingfish display a magnitude of size heterogeneity similar to other marine species with small pelagic larvae reared in captivity, the sample sizes determined in the present study can act as a general guideline for larval fish studies.
|
|
