An illuminator for observing and photographing precipitin reactions in agar
Abstract not available.
Journal of the Biological Photographic Association↗
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Sedimentation across the central California oxygen minimum zone: an alternative coastal upwelling sequence
Distribution, abundance, and diversity of terrigenous, authigenous, and biogenous material provide evidence of the effect of bottom currents and oxygen minimum zone (OMZ) on continental slope sedimentation offshore central California. Box core samples and bottom photographs collected across the oxygen minimum zone of the coastal upwelling system were analyzed for lithologic and biologic trends. Three major OMZ facies are identified, along the upper and lower edges of the OMZ and one at its core. The upper boundary (525 m) of the central California OMZ (< 0.5 ml/liter O 2 ) is characterized by glauconitic gravelly sands relatively depleted in detrital silicates and enriched in carbonate and total organic carbon (TOC). These upper-boundary sands also have a maximum macrofauna density and a high abundance of foraminiferal fragments (> 80% of total forams) with Cassidulina the dominant benthic foraminifer. With increasing water depth, decreasing current speed, and dissolved oxygen content toward the core of the OMZ (750 m), grain size, glauconite, carbonate, TOC, and foraminiferal fragments all decrease as the abundance of mica and detrital silicates increase. The greatest number of genera of benthic foraminifera occurs at the core of the OMZ where their relative concentration is at a minimum and Bolivina is the dominant genus. No heavily calcified macrofauna were found at the core of the OMZ; however, near-surface sediments are highly bioturbated. As the lower boundary (1,025 m) of the OMZ is approached, grain size and abundance of detrital silicates continue to decrease as glauconite disappears. Concomitantly, the relative abundance of mica, carbonate, TOC, siliceous microfauna, benthic foraminifers, and foram fragments increase. The benthic foraminifer population consists largely (> 40%) of Globobulimina and Praeglobobulimina . The lower edge of the OMZ is highlighted by a distinct peak of fecal pellets (25% of sand-size material). Lithofacies and biofacies associated with the OMZ are controlled by an interplay of oceanic circulation, dissolved oxygen concentrations, and possibly by increased biological activity within the OMZ edge environment and slight changes in the slope gradient. Recognition of key lithofacies and biofacies trends may prove to be powerful paleoenvironmental/paleoceanographic indicators and may be useful in identifying ancient zones of upwelling analogous to the modern central California system where phosphorites, organic-rich shales, and/or chert are absent.
Journal of Sedimentary Petrology↗
Deep-water chaunacid and lophiid anglerfishes (Pisces: Lophiiformes) off the Southeastern United States
Recent research cruises to deep (80–910 m) reef habitats off the south-eastern U.S. and in the northern Gulf of Mexico have provided new information on the diagnostic characteristics, behaviours, colour patterns in life, bottom associations, distributions and maximum sizes of species of the anglerfish genera Chaunax , Lophiodes and Sladenia . Chaunax stigmaeus occurred much further south than previously known (Blake Plateau off South Carolina), and all C. stigmaeus observed were found associated with dense beds of dead coral ( Lophelia pertusa ) rubble or on broken hard bottom. In contrast, Chaunax suttkusi was found on soft bottoms. Chaunax stigmaeus and C. suttkusi appear to be sympatric over a major portion of their ranges. Because knowledge of pigmentation in live or freshly caught Chaunax is critical to distinguish some members of the genus, changes in the colouration of C. suttkusi were noted and documented photographically immediately after death and after fixation. The yellow spots found on some, but not all specimens, temporarily disappeared completely after death, but they reappeared after fixation, slowly disappearing thereafter along with other carotenoid pigments. Lophiodes beroe and Lophiodes monodi were collected for the first time off the Atlantic coast of the U.S., being previously known only from the Gulf of Mexico, Caribbean Sea and the northern coast of South America. For both species ( L. beroe and L. monodi ), the collections included the two largest known representatives of the species (400 and 325 mm standard length, respectively). Lophiodes beroe commonly occurred on L. pertusa rubble, and seemed to prefer this habitat. Occupying such a habitat that is deep and difficult to sample probably explains how this common species escaped detection. Only a single L. monodi was collected or observed, so this species appears to be uncommon in this geographic area or at least so on coral rubble habitat. Detailed aspects of the colour patterns of both species were noted. In particular, L. beroe displayed a characteristic pattern of white patches in life that were not apparent after death. The first photographic documentation of the colour pattern in life and of the pharyngeal pigmentation of Lophiodes reticulatus is provided. The third known specimen of Sladenia shaefersi , and the first to be taken in U.S. waters was collected from coral rubble near the base of a steep 200 m scarp on the Blake Plateau.
Gulf of Mexico↗