Macroparasites of angelfish Brama brama (Bonnaterre, 1788) in the southern Benguela Current ecosystem

The angelfish Brama brama is a mesopelagic species distributed circumglobally in temperate to warm-temperate waters, including continental-shelf-edge and upper-slope waters of the Benguela Current ecosystem. Little is known about the parasite assemblage of Benguela B. brama, with only three parasite taxa having previously been documented from this species in the southern Benguela. This study describes the macroparasites recorded from 35 B. brama collected during research surveys off the west coast of South Africa in 2015 and 2016. A total of six macroparasite taxa were documented, including the nematode Anisakis pegreffii, the copepod Hatschekia conifera, the cestode Hepatoxylon trichiuri, an acanthocephalan from the genus Rhadinorhynchus, a monogenean from the family Diclidophoridae, and an unidentified species. Three of these (He. trichiuri, Rhadinorhynchus sp. and the unidentified species) had not previously been found to infect B. brama. The most prevalent macroparasite taxa were A. pegreffii (94%), the unidentified species (71%) and Ha. conifera (60%). Two of the parasites, Ha. conifera and He. trichiuri, showed seasonal variation in infection, and infection with the latter was positively correlated with host length. These findings increase our knowledge of B. brama biology and contribute to our understanding of the biodiversity of the southern Benguela ecosystem.     

Arsenic and antimony in geothermal waters of Yellowstone National Park,Wyoming, USA

A total of 268 thermal spring samples were analyzed for total soluble As using reduced molybdenum-blue; 27 of these samples were also analyzed for total Sb using flame atomic absorption spectrometry. At Yellowstone the $\text{Cl}\text{As}$ atomic ratio is nearly constant among neutral-alkaline springs with Cl > 100 mg L^?1, and within restricted geographic areas, indicating no differential effects of adiabatic vs. conductive cooling on arsenic. The $\text{Cl}\text{As}$ ratio increases with silica and decreases with decreasing $\text{Cl}\text{ΣCO}{}_3$; the latter relationship is best exemplified for springs along the extensively sampled SE-NW trend within the Lone Star-Upper-Midway Basin region. The relationship between $\text{Cl}\text{As}$ and $\text{Cl}\text{ΣCO}{}_3$ at Yellowstone suggests a possible rock leaching rather than magmatic origin for much of the Park's total As flux. Condensed vapor springs are low in both As and Cl. Very high $\text{Cl}\text{As}$ ratios ( > 1000) are associated exclusively with highly diluted (Cl < 100 mg L^?1) mixed springs in the Norris and Shoshone Basins and in the Upper White Creek and Firehole Lake areas of Lower Basin. The high ratios are associated with acidity and/or oxygen and iron; they indicate precipitation of As following massive dilution of the Asbearing high-Cl parent water.Yellowstone Sb ranged from 0.009 at Mammoth to 0.166 mg L^?1 at Joseph's Coat Spring. Within basins, the $\text{Cl}\text{Sb}$ ratio increases as the $\text{Cl}\text{ΣCO}{}_3$ ratio decreases, in marked contrast to As. Mixed springs also have elevated $\text{Cl}\text{Sb}$ ratios. White (1967) and Weissberg (1969) previously reported stibnite (Sb₂S₃), but not orpiment (As₂S₃), precipitating in the near surface zone of alkaline geothermal systems.     

Fluorapatite and fluorite solubility controls on geothermal waters in Yellowstone National Park

Potential solubility controls on phosphorus in Yellowstone National Park geothermal waters were investigated using the analytical phosphate estimates of Stauffer and Thompson (1978), the computer program, WATEQF, and adopting the equilibrium constant: $\text{log}\text{K}{}_{\mathrm{25°}}\text{= ?61.4}$ for fluorapatite (FAP = Ca₅(PO₄)₃F) dissolution. The near-boiling high-Cl geyser and spring effluents are at or near saturation with respect to (with) FAP. The sixteen representative springs in this category had FAP saturation indices ($\text{S.I. =}\text{log}\text{IAP/K}{}_{\mathrm{r}}$) ranging from ? 3.2 to +4.9 and averaging +0.9. The strongly positive indices were all associated with the highly alkaline conditions resulting from adiabatic cooling in the near surface environment. Hot spring waters indicating extensive dilution (reduced Cl) by meteoric water have lower pH's, and despite PO₄ and Ca concentrations an order of magnitude higher than the geysers, are still frequently undersaturated with FAP. The travertine-depositing “Mixed-water” springs are invariably supersaturated with FAP at ground surface and at or near saturation with hydroxylapatite. Supersaturation may result from kinetic inhibition of apatite crystallization by the elevated Mg²⁺, HCO₃^?, and lower temperatures in these springs. The phosphates may be residuals of the meteoric dilution water.Separately, if Strübel's temperature-dependent estimates of fluorite (CaF₂) solubility are adopted, the high-Cl geysers and springs on “Geyser Hill” and at Norris are consistently undersaturated with CaF₂ at the 90–100° orifice temperatures. The apparent disequilibrium may reflect fluorite equilibration at the much higher temperatures (> 200°C) in the deeper enthalpy reservoirs.     

New seismic images of the crust in the central Trans-Hudson Orogen of Saskatchewan

A reprocessing program to enhance the correlation between the surface geology and the seismic data has been completed for seismic line 9 (eastern 100 km) and line 10 in the central region of the Trans-Hudson Orogen of Saskatchewan, Canada. The new seismic images through lateral continuity of reflectivity provide sufficient detail to resolve the discrepancy between the low-dipping, layer-parallel and dextral-reverse nature of the Sturgeon-Weir shear zone (line 9) observed in the field and its steeply dipping (apparent) normal displacement character interpreted on the basis of the initial processing. Furthermore, the new interpretation provides a strong confirmation of the role of Pelican Thrust as a major detachment zone — the main `sole thrust' — along which juvenile allochthons have been carried across the Archaean microcontinental block. The images are also refined enough to suggest: (a) a boundary within the Pelican Thrust between its internal and external suites; (b) a possible boundary separating a lower (older?) Archaean basement from its upper (younger?) counterpart; and (c) sub-Moho events (M2) which reveal possible involvement of the upper mantle in the collisional tectonic process in addition to the well defined Moho (M1) which probably represents the youngest of the post-collisional detachments.     

LIGHT THROWN ON GENERAL PROBLEMS BY THE ROUMANIAN RESULTS

The sedimentological characteristics of typical flysch sediments are confirmed for the Roumanian flysch. The emplacement by turbidity currents of the coarse beds alternating with the shales and marls is again abundantly confirmed by the studies in the area under discussion.     

Reef fishes recruited at midwater coral nurseries consume biofouling and reduce cleaning time in Seychelles,Indian Ocean

In coral reef restoration, coral gardening involves rearing coral fragments in underwater nurseries prior to transplantation. These nurseries become fish-aggregating devices and attract biofouling. We hypothesised that: (1) the presence of corals at a nursery is critical to recruit fish assemblages and (2) the recruited fish assemblages control biofouling, reducing person-hours invested in nursery cleaning. Three midwater coral nurseries were deployed at 8?m depth for 27 months within the marine protected area of Cousin Island Special Reserve, Seychelles, Indian Ocean. Each nursery consisted of a 6?m×6?m PVC pipe frame, layered with a recycled 5.5-cm-mesh tuna net. Human cleaning effort was calculated based on daily dive logs. Nursery-associated fish assemblages and behaviour were video-recorded prior to harvesting corals after a 20-month growth period and seven months post-coral harvesting. The density (ind. m–2) of blue-yellow damselfish Pomacentrus caeruleus was 12–16 times higher when corals were present than when corals were absent at the nurseries. Fish assemblages recruited into the nurseries included three trophic levels, from herbivores to omnivores, in six families: Ephippidae, Pomacentridae, Labridae (Scarinae), Gobiidae, Siganidae and Monacanthidae. Higher abundance of large fish (total number of individuals) resulted in 2.75 times less person-hours spent in nursery cleaning. These results have important implications for cost-effective coral reef restoration.     

THE SASKATCHEWAN FIREBALL OF 1922 AND A POSSIBLE LINK WITH THE WYNYARD CHONDRITE

A brilliant smoking meteor appeared in a clear sky in bright sunlight at 11 a.m., July 24, 1922 near Wynyard, Saskatchewan, Canada. The sight and thunderous sounds were witnessed by many hundreds of people in the rural district but no craters or meteorites were found at that time. Investigation and interviews with surviving witnesses in 1981 indicated a defined area near Big Quill Lake in which a meteorite may have fallen. Field investigation led to the Wynyard meteorite which had been found by a farmer sometime in the late 1960's at 104° 11'W 51°33'N. The Wynyard meteorite is a chondrite weighing 3.5 kg. It is moderately weathered and it may or may not have been part of the 1922 fall.