Evaluation of otolith microstructures for ageing of larval white sturgeon

2021 ◽  
Author(s):  
Andrea Y. Frommel ◽  
Vahab Pourfaraj ◽  
Colin J Brauner ◽  
D. Steven O. McAdam
Keyword(s):  
Habitat Degradation ◽  
Ring Width ◽  
Ring Structure ◽  
White Sturgeon ◽  
Alizarin Red ◽  
Recruitment Failure ◽  
Promising Tool ◽  
Laboratory Calibration ◽  
Feeding Regimes ◽  
Calibration Study

Sturgeon populations are endangered worldwide, mainly due to habitat degradation and overexploitation causing recruitment failure. Understanding of early development, survival and growth in sturgeon is limited by a lack of a validated method to directly estimate larval age. In a laboratory calibration study, we reared white sturgeon larvae from hatch for 3 weeks at 12 and 16°C and two feeding regimes (fed and unfed) to determine the usefulness of their vateritic micro-otoconia for larval ageing and the influence of environmental factors on ring structure and size. By marking the otoliths twice at known ages with Alizarin Red S, we were able to confirmed the presence of daily rings in the largest micro-otoconia and the feasibility of ageing larval sturgeon using otoliths. Three observers blind to age and treatment assessed larval age from daily rings with an overall precision of 67-82% and 30-70% accuracy, dependent on larval age. Neither temperature nor feeding had a significant effect on ring width or readability. Thus, ageing with otoliths in sturgeon is a promising tool in sturgeon conservation efforts.

scholarly journals Inter-laboratory Calibration Study for Dioxins in Food/Feedstuff using DR-CALUX Assay

2007 ◽  
Vol 17 (3) ◽  
pp. 483-493
Author(s):  
Go SUZUKI ◽  
Harrie BESSELINK ◽  
Emiel FELZEL ◽  
Abraham BROUWER ◽  
Shin-ichi SAKAI ◽  
...  
Keyword(s):  
Laboratory Calibration ◽  
Calibration Study ◽  
Calux Assay

scholarly journals Down, but not out: Recent decline of Berg–Breede River whitefish (Barbus andrewi) in the upper Hex River, South Africa

Koedoe ◽  
2017 ◽  
Vol 59 (1) ◽  
Author(s):  
Jeremy M. Shelton ◽  
N. Dean Impson ◽  
Shaun Graham ◽  
Karen J. Esler
Keyword(s):  
Native Species ◽  
Habitat Degradation ◽  
Clarias Gariepinus ◽  
Cape Floristic Region ◽  
Smallmouth Bass ◽  
River Population ◽  
Agricultural Impacts ◽  
Recruitment Failure ◽  
Conservation Actions ◽  
Native Fishes

The Berg–Breede River whitefish, Barbus andrewi, an endangered Cape Floristic Region endemic, was once widespread in both the Berg and Breede River catchments. However, its distribution has been strongly reduced, apparently by human-related activities, over the last century, and the Hex River now contains one of the last recruiting populations within its native range. This population was last surveyed by Christie who found that the species occurred in six pools over a 9-km stretch of the upper Hex River. We re-surveyed fish populations at Christie’s sites in 2015 to evaluate differences in the fish community between 2002 and 2015. Our data indicated that the distribution of B. andrewi in the Hex River has declined from six to four pools and that its density in the study area in 2015 (0.57 fish per 100 m2 ± 0.31 fish per 100 m2 ) was more than fivefold lower than that recorded in 2002 (3.39 fish per 100 m2 ± 1.40 fish per 100 m2 ). Moreover, small size classes of B. andrewi (< 10 cm) were largely absent in 2015, indicating recruitment failure in recent years. Habitat degradation, exacerbated by a severe flood in 2008, and recent invasions by predatory non-native fishes (smallmouth bass, Micropterus dolomieu and sharptooth catfish, Clarias gariepinus) are identified as likely causes of this decline. Cape kurper, Sandelia capensis, another native species, was relatively common in 2002 but not recorded in 2015, whereas the density of native Breede River redfin, Pseudobarbus burchelli, was higher in 2015 than in 2002. Urgent conservation actions including managing non-native fish invasions and mitigating agricultural impacts on aquatic habitat are required to prevent further decline, and possible extirpation, of the Hex River population of B. andrewi.Conservation implications: Urgent conservation actions including preventing further increases in the abundance and distribution of non-native fishes, and improving habitat and water quality through mitigating agricultural impacts, are required to prevent further decline, and possible extirpation, of the Hex River population of B. andrewi.

Biology, Management, and Protection of North American Sturgeon

2002 ◽  
Keyword(s):  
Industrial Development ◽  
Species Abundance ◽  
White Sturgeon ◽  
River Ecosystem ◽  
Mortality Factors ◽  
The Past ◽  
Recruitment Failure ◽  
River Basin Development ◽  
Kootenai River ◽  
Natural Recruitment

<em>Abstract.</em>—The Kootenai River ecosystem in Idaho, Montana and British Columbia, Canada has been altered and degraded during the past 75 years. By the mid-1960s, phosphorus concentrations increased 15-fold, and nitrogen doubled from baseline conditions in the Kootenai River due to municipal and industrial development. Pollution abatement beginning in the late 1960s, and subsequent impoundment of the Kootenai River (Libby Dam 1972) reversed this culturally eutrophic condition. By the mid-1990s the Kootenai River was classified as ultraoligotrophic, as it remains today. Reverberating trophic responses to cultural denutrification were temporally correlated with the collapse of the functional Kootenai River ecosystem and its endemic white sturgeon <em>Acipenser transmontanus</em> population. Natural recruitment of white sturgeon in the Kootenai River has been virtually absent during the past 30 years, with several exceptions. In response to consistent natural recruitment failure, the Kootenai River white sturgeon population was listed as endangered on September 6, 1994, under the U.S. Endangered Species Act. Depressed biological productivity, alteration of spawning and rearing habitats, fish species abundance changes, altered predator–prey dynamics, and consistent white sturgeon recruitment failure constituted biological (ecological) responses to Kootenai River Basin development. We propose an integrated hypothesis to explain natural recruitment failure in the Kootenai River white sturgeon population. This hypothesis suggests that, during some years, natural recruitment failure may have been caused by female stock limitation. In other years (those lacking female stock-limitation), we propose that recruitment failure was due to one or more postspawning early life mortality factors.

scholarly journals Contribution of Xylem Anatomy to Tree-Ring Width of Two Larch Species in Permafrost and Non-Permafrost Zones of Siberia

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1343
Author(s):  
Margarita I. Popkova ◽  
Vladimir V. Shishov ◽  
Eugene A. Vaganov ◽  
Marina V. Fonti ◽  
Alexander V. Kirdyanov ◽  
...  
Keyword(s):  
Tree Ring ◽  
Cell Structure ◽  
Ring Width ◽  
Local Environment ◽  
Ring Structure ◽  
Climatic Conditions ◽  
Tree Ring Width ◽  
Linear Modeling ◽  
Xylem Cell ◽  
Larch Species

Plants exhibit morphological and anatomical adaptations to cope the environmental constraints of their habitat. How can mechanisms for adapting to contrasting environmental conditions change the patterns of tree rings formation? In this study, we explored differences in climatic conditions of permafrost and non-permafrost zones and assessed their influence on radial growth and wood traits of Larix gmelinii Rupr (Rupr) and Larix sibirica L., respectively. We quantified the contribution of xylem cell anatomy to the tree-ring width variability. Comparison of the anatomical tree-ring parameters over the period 1963–2011 was tested based on non-parametric Mann-Whitney U test. The generalized linear modeling shows the common dependence between TRW and the cell structure characteristics in contrasting environments, which can be defined as non-specific to external conditions. Thus, the relationship between the tree-ring width and the cell production in early- and latewood are assessed as linear, whereas the dependence between the radial cell size in early- and latewood and the tree-ring width becomes significantly non-linear for both habitats. Moreover, contribution of earlywood (EW) and latewood (LW) cells to the variation of TRW (in average 56.8% and 24.4% respectively) was significantly higher than the effect of cell diameters (3.3% (EW) and 17.4% (LW)) for the environments. The results show that different larch species from sites with diverging climatic conditions converge towards similar xylem cell structures and relationships between xylem production and cell traits. The work makes a link between climate and tree-ring structure, and promotes a better understanding the anatomical adaptation of larch species to local environment conditions.

Nesting behaviour of the endangered Mary River turtle: monitoring and modelling to inform e-flow strategies

2018 ◽  
Vol 66 (1) ◽  
pp. 15 ◽  
Author(s):  
T. Espinoza ◽  
M. Connell ◽  
S. Marshall ◽  
R. Beukeboom ◽  
A. McDougall
Keyword(s):  
Life History ◽  
Water Resource ◽  
Habitat Degradation ◽  
Resource Development ◽  
Environmental Drivers ◽  
Water Resource Development ◽  
Protection Measures ◽  
Recruitment Failure ◽  
Natural Flow ◽  
Nesting Behaviour

The Mary River turtle (Elusor macrurus) is an endemic, monotypic species with multiple impacts across its life-history, including overharvesting of eggs, nest predation and habitat degradation. Long-term recruitment failure has led to protection measures established under state, federal and international authority. Previous research has demonstrated that E. macrurus lives instream but nests on river banks, requiring specific habitat for breeding, nesting and recruitment. Ecohydrological rules represent the critical water requirements contributing to a species’ life history and can be used to develop and assess environmental flow strategies for species affected by water resource development. This study investigated the nesting behaviour of E. macrurus, including the environmental drivers that affect nest inundation. Monitoring showed that nesting by E. macrurus peaked in October and November, driven by rainfall events (>10 mm), with potential impacts from flow events (20% of nests established <2.5 m above water level at time of nesting). These ecohydrological rules were modelled against 109 years of simulated natural flow and rainfall data. The ‘potential nesting and nest inundation’ (PNNI) indicator revealed that nesting for E. macrurus was assured in a majority of years under the natural flow scenario. The results of this study will inform the development and assessment of e-flow strategies for nesting by E. macrurus in terms of current, and future water resource development, along with climate change impacts.

scholarly journals Reducing Nitrogen Dosage in Triticum durum Plants with Urea-Doped Nanofertilizers

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1043 ◽  
Author(s):  
Gloria B. Ramírez-Rodríguez ◽  
Cristina Miguel-Rojas ◽  
Gabriel S. Montanha ◽  
Francisco J. Carmona ◽  
Gregorio Dal Sasso ◽  
...  
Keyword(s):  
Triticum Durum ◽  
Positive Control ◽  
Amorphous Precursor ◽  
Alizarin Red ◽  
Sustainable Practices ◽  
Similar Morphology ◽  
Promising Tool ◽  
Yield And Quality ◽  
Calcium Phosphate Nanoparticles

Nanotechnology is emerging as a very promising tool towards more efficient and sustainable practices in agriculture. In this work, we propose the use of non-toxic calcium phosphate nanoparticles doped with urea (U-ACP) for the fertilization of Triticum durum plants. U-ACP nanoparticles present very similar morphology, structure, and composition than the amorphous precursor of bone mineral, but contain a considerable amount of nitrogen as adsorbed urea (up to ca. 6 wt % urea). Tests on Triticum durum plants indicated that yields and quality of the crops treated with the nanoparticles at reduced nitrogen dosages (by 40%) were unaltered in comparison to positive control plants, which were given the minimum N dosages to obtain the highest values of yield and quality in fields. In addition, optical microscopy inspections showed that Alizarin Red S stained nanoparticles were able to penetrate through the epidermis of the roots or the stomata of the leaves. We observed that the uptake through the roots occurs much faster than through the leaves (1 h vs. 2 days, respectively). Our results highlight the potential of engineering nanoparticles to provide a considerable efficiency of nitrogen uptake by durum wheat and open the door to design more sustainable practices for the fertilization of wheat in fields.

scholarly journals Reduced-Impact Logging Maintain High Moss Diversity in Temperate Forests

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 383
Author(s):  
Enrique Hernández-Rodríguez ◽  
Luis H. Escalera-Vázquez ◽  
Deneb García-Ávila ◽  
Miguel Montoro Girona ◽  
Eduardo Mendoza
Keyword(s):  
Community Structure ◽  
Forest Management ◽  
Habitat Degradation ◽  
Alpha Diversity ◽  
Biodiversity Loss ◽  
Forest Harvesting ◽  
Annual Rainfall ◽  
Promising Tool ◽  
Impact On Biodiversity ◽  
The Impact

Forestry harvesting represents an important economic activity around the world. Habitat degradation due to forest harvesting contributes to biodiversity loss; therefore, it is necessary to implement logging management aimed at reducing its impact. Forest management by reduce-impact logging (RIL) involves cutting trees following regulations focused on diminishing the impact on biodiversity by following harvesting plans based on forestry inventories and participation of trained workers. In Mexico, RIL is applied mainly in temperate habitats and its effectiveness has been assessed based on vascular plants. In this study, we analyzed the diversity and community structure of terrestrial and epiphytic mosses in managed (sites number = 3) and conserved (sites number = 3) sites in the temperate forest of Sierra Juárez, Oaxaca, Mexico. Likewise, we evaluated the potential function of mosses as indicators of habitat degradation. Environmental variables were also quantified at local (canopy coverage, altitude, daily temperature, and light) and regional (total annual rainfall, orientation, and slope) scales to evaluate potential relationships with the community and species diversity. We documented 70 mosses species with a diversity (alfa, beta) and community structure similar between managed and conserved sites. For terrestrial mosses, we found marginal differences in their communities, likely related to species coverture variation in managed sites. The diversity and community structure epiphytic mosses were not statistically different in managed and conserved sites. Only the daily variation in light intensity was positively related to the variation of alpha diversity of epiphytic mosses. The species Dicranum sumichrastii Duby and Leptodontium viticulosoides (P. Beauv.) Wijk & Margad. can be considered as ecological indicators for conserved and managed sites, respectively, likely due to their relationship with light and humidity conditions. Our results suggest that that forest management by RIL could be considered as a promising tool to balance timber production and moss diversity.

The hydrogen distribution in galaxies

1967 ◽  
Vol 31 ◽  
pp. 189-197 ◽  
Author(s):  
Morton S. Roberts
Keyword(s):  
Ring Width ◽  
Neutral Hydrogen ◽  
Major Axis ◽  
Ring Structure ◽  
Hydrogen Distribution ◽  
Ring Radius ◽  
Systemic Velocity ◽  
Irregular Galaxies ◽  
The Galaxy ◽  
Ring Structures

Results of 21-cm line observations with the 300-foot telescope are summarized. Along the major axis of M 31, the peaks in the distribution of neutral hydrogen correlate closely (but do not exactly coincide) with the optical spiral arms. The distribution of hydrogen over the galaxy shows a ring pattern; the same is true in M 33.Resolution of such ring structures may be facilitated by consideration of profile integrals over a restricted velocity range around the systemic velocity. Out of nine spiral systems studied, with minor axis &gt; 10′ (arc), only NGC 628 exhibits no ring. The ratios ring radius to ring width and optical radius to ring radius vary little about averages 2·5 and 1·7. In two irregular galaxies, no ring structure was observed.Neutral-hydrogen haloes, if present, can only be studied in large edge-on systems. In NGC 4244 and 7640, the upper limit to the density of neutral hydrogen in the halo is 0·001 cm-3. Qualitative considerations indicate that a similar value may apply in the Galaxy.

Retrospective weight-of-evidence analysis identifies substrate change as the apparent cause of recruitment failure in the upper Columbia River white sturgeon (Acipenser transmontanus)

2015 ◽  
Vol 72 (8) ◽  
pp. 1208-1220 ◽  
Author(s):  
D. Steven O. McAdam
Keyword(s):  
Columbia River ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Weight Of Evidence ◽  
Recruitment Failure ◽  
Evidence Evaluation ◽  
Evidence Analysis ◽  
Riverine Fish ◽  
Recruitment Time ◽  
Spawning Sites

A weight-of-evidence evaluation of the potential cause of white sturgeon (Acipenser transmontanus) recruitment failure in the upper Columbia River evaluated 12 recruitment-failure hypotheses based on nine criteria. Recruitment-failure timing was estimated by identifying breakpoints in the hindcasted recruitment time series for three of four spatially distinct groups. Observed spatial and temporal recruitment decline patterns were then compared with expected patterns for each hypothesis (e.g., flow, temperature, turbidity, contaminants, and changes to the riverine fish community). The weight-of-evidence evaluation also considered criteria including coherence with theoretical, factual, and biological evidence and responses to impact reversal. Recruitment failure began about 1968, coincident with the initiation of upstream mainstem flow regulation. An 8- or 9-year lag in the recruitment decline of the Waneta group was particularly informative for hypothesis evaluations. The identification of increased fine substrates at spawning sites as the most plausible explanation for chronic recruitment failure has important implications regarding the apparent life stages affected and potential restoration approaches.

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