2,392 research outputs found
Assessment of the vendace population of Bassenthwaite Lake including observations on vendace spawning grounds. Progress Report for Period August 2007 to January 2008
The efficacy of sanctuary areas for the management of fish stocks and biodiversity in WA waters
Debate concerning the relative benefits of marine protected areas (MPAs) for the management of marine resources can often reflect unrecognized differences in the scope, scale and definitions of the objectives being sought by various Government or community bodies. There can also be different opinions on the level of protection required for an area to be considered an ‘MPA’ and functional definitions for both the biological diversity and ecosystems within these areas are often lacking. This paper seeks to outline the relative efficiency and effectiveness of MPAs, especially no-take sanctuary areas, compared to other strategies currently employed to help achieve the main objective of the Western Australian (WA) Fish Resources Management Act (FRMA) 1994, which is “to conserve fish* and protect their environment”. This objective covers the conservation of most of the marine resources of the WA coast, including fish stock management; habitat protection and biodiversity generally out to the 200 m depth contour
Polyimide processing additives
A process for preparing polyimides having enhanced melt flow properties is described. The process consists of heating a mixture of a high molecular weight poly-(amic acid) or polyimide with a low molecular weight amic acid or imide additive in the range of 0.05 to 15 percent by weight of additive. The polyimide powders so obtained show improved processability, as evidenced by lower melt viscosity by capillary rheometry. Likewise, films prepared from mixtures of polymers with additives show improved processability with earlier onset of stretching by TMA
Long-term changes in the diet of pike (Esox lucius), the top aquatic predator in a changing Windermere
1. Pike (Esox lucius) is a key and flexible piscivore in many fresh waters of the northern temperate zone, but no previous studies have provided a continuous long-term perspective on its diet in response to changing environmental conditions. Here, we describe its winter diet from 1976 to 2009 in the North and South Basins of the lake of Windermere, U.K., where climate change, eutrophication and species introductions have combined to induce fundamental changes in the fish community.
2. A total of 6637 adult pike (fork length 390 to 1090 mm) was examined and found to have consumed a total of 4436 fish prey of which 98% of individuals identifiable to species comprised native Arctic charr (Salvelinus alpinus), brown trout (Salmo trutta), perch (Perca fluviatilis) and pike and non-native roach (Rutilus rutilus). Over the 34-year study period, the dietary importance of the salmonids Arctic charr and brown trout decreased, while that of the percid perch, the esocid pike and particularly the cyprinid roach increased. These changes were particularly marked in the more eutrophicated South Basin of the lake.
3. The above chronological trends in species-specific contributions to the diet composition of pike had considerable overall impacts. In the 1970s, pike diet composition was dominated by Arctic charr and brown trout which together comprised 94% of the diet. In contrast, in the 2000s, these two species accounted for just 55% of the diet, with perch and roach now comprising 41%.
4. Recent changes observed in the Windermere fish community of a decrease in native salmonids and an increase in cyprinids are consistent with the generally expected effects of climate change in the northern temperature zone. Here, we have shown that they have led to corresponding changes in the diet composition of pike. In turn, this may have implications for lake’s food web structure through shortening food chain length from the primary producers to the top aquatic predator
Harvest-induced disruptive selection increases variance in fitness-related traits
The form of Darwinian selection has important ecological and management implications. Negative effects of harvesting are often ascribed to size truncation (i.e. strictly directional selection against large individuals) and resultant decrease in trait variability, which depresses capacity to buffer environmental change, hinders evolutionary rebound and ultimately impairs population recovery. However, the exact form of harvest-induced selection is generally unknown and the effects of harvest on trait variability remain unexplored. Here we use unique data from the Windermere (UK) long-term ecological experiment to show in a top predator (pike, Esox lucius) that the fishery does not induce size truncation but disruptive (diversifying) selection, and does not decrease but rather increases variability in pike somatic growth rate and size at age. This result is supported by complementary modelling approaches removing the effects of catch selectivity, selection prior to the catch and environmental variation. Therefore, fishing most likely increased genetic variability for somatic growth in pike and presumably favoured an observed rapid evolutionary rebound after fishery relaxation. Inference about the mechanisms through which harvesting negatively affects population numbers and recovery should systematically be based on a measure of the exact form of selection. From a management perspective, disruptive harvesting necessitates combining a preservation of large individuals with moderate exploitation rates, and thus provides a comprehensive tool for sustainable exploitation of natural resources
Experience in Production of 68Ga-DOTA-NOC for Clinical Use Under an Expanded Access IND
[68Ga]Ga-DOTA-NOC was produced under an Expanded Access IND for 174 clinical PET/CT studies to evaluate patients with neuroendocrine tumors. Production employed either the TiO2-based Eckert & Ziegler (EZAG) 68Ge/68Ga-generator (with fractionated elution), or the SiO2-based ITG 68Ge/68Ga-generator. In both cases, [68Ga]Ga-DOTA-NOC was reliably produced, without pre-synthesis purification of the68Ga generator eluate, using readily-implemented manual synthesis procedures. [68Ga]Ga-DOTA-NOC radiochemical purity averaged 99.2±0.4%. Administered 68Ga dose averaged 181±22 MBq, and administered peptide mass averaged 43.2±5.2 µg (n=47) and 23.9±5.7 µg (n=127), respectively, using the EZAG and ITG generators. At dose expiration, 68Ge breakthrough in the final product averaged 2.7×10−7% and 5.4×10−5% using the EZAG and ITG generators, respectively
The Origin of Nitrogen on Jupiter and Saturn from the N/N Ratio
The Texas Echelon cross Echelle Spectrograph (TEXES), mounted on NASA's
Infrared Telescope Facility (IRTF), was used to map mid-infrared ammonia
absorption features on both Jupiter and Saturn in February 2013. Ammonia is the
principle reservoir of nitrogen on the giant planets, and the ratio of
isotopologues (N/N) can reveal insights into the molecular
carrier (e.g., as N or NH) of nitrogen to the forming protoplanets, and
hence the source reservoirs from which these worlds accreted. We targeted two
spectral intervals (900 and 960 cm) that were relatively clear of
terrestrial atmospheric contamination and contained close features of
NH and NH, allowing us to derive the ratio from a single
spectrum without ambiguity due to radiometric calibration (the primary source
of uncertainty in this study). We present the first ground-based determination
of Jupiter's N/N ratio (in the range from to
), which is consistent with both previous space-based studies
and with the primordial value of the protosolar nebula. On Saturn, we present
the first upper limit on the N/N ratio of no larger than
for the 900-cm channel and a less stringent
requirement that the ratio be no larger than for the
960-cm channel ( confidence). Specifically, the data rule out
strong N-enrichments such as those observed in Titan's atmosphere and in
cometary nitrogen compounds. To the extent possible with ground-based
radiometric uncertainties, the saturnian and jovian N/N ratios
appear indistinguishable, implying that N-enriched ammonia ices could
not have been a substantial contributor to the bulk nitrogen inventory of
either planet, favouring the accretion of primordial N from the gas phase
or as low-temperature ices.Comment: 33 pages, 19 figures, manuscript accepted for publication in Icaru
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