Deep-sea sedimentary processes in the Argentine Basin revealed by 3.5 kHz echograms
by Adam Klaus, "A thesis presented to the faculty of Moss Landing Marine Laboratories.", Thesis (M.S.) -- San Jose State University, 1986., The regional distribution of eleven 3.5 kHz seismic echo types reveals the areal extent of deep-sea sedimentary processes in the Argentine Basin. A correlation between echo character and the relative abundance of sand and silt layers in piston cores allows the pattern of coarse terrigenous sediment dispersal to be identified. This relationship indicates that the majority of coarse sediment bypasses the continental slope and rise. This coarse sediment is deposited on the proximal abyssal plain with progressively lower amounts basinward, and lower abundances on the shallow margin. Scarps, irregular and blocky hyperbolic zones, and transparent layers along the Argentine continental margin have echo characteristics similar to those of documented gravity-controlled mass flow deposits. A large area of mass flow deposits, covering at least 5x10^4 km^2, is located on the continental rise and adjacent abyssal plain east of the Rio de la Plata. A field of migrating mud waves, approximately 1.0x10^6 km^2 in extent, occurs on the sediment drifts of the central basin. Mud waves range in amplitude up to 137m and average 26m, and have wavelengths of about 3 to 7 km. The presence of migrating mud waves suggests widespread current-controlled sedimentation. It is inferred, however, that these mud waves form in areas of relatively weak flow in the interior basin because the benthic circulation is characterized by strong Antarctic Bottom Water (AABW) flow along the western and southern margins and by weak flow in the central basin. A variety of hyperbolic echoes on the abyssal plain adjacent to the Argentine continental margin, south of the Rio Grande Rise, and in the Georgia Basin, are interpreted as current-produced erosional / depositional bedforms, although downslope sedimentary processes may also produce similar hyperbolic echoes. The distribution of bedforms inferred from seismic echo character suggests that sediment is supplied to the basin principally by gravity-controlled mass flows. Sediment entrained in AABW is a secondary source. Gravity-controlled mass flows are predominantly limited to the Argentine continental margin. Sediment from both sources is winnowed by strong AABW flow along the Argentine continental rise. The fine-grained chaff is transported to the central basin where it is deposited as migrating mud waves in regions of relatively weaker bottom current.
A simplified ATP assay for planktonic organisms with improved extraction efficiency
by Julie C. Kuo, "A thesis presented to the faculty of Moss Landing Marine Laboratories.", Thesis (M.S.) -- San Jose State University, 2015., The adenosine triphosphate (ATP) assay, a proxy of living biomass (used by oceanographers for more than 50 years), was investigated for its potential as a ballast water compliance monitoring tool. Though some ATP assays are reliable for estimating living biomass in specific microbial communities, those assays may be less than optimal for others. For this project, an ATP assay was developed to quantify ATP concentration in most (if not all) aquatic microbial communities; it was also optimized for convenient and rapid assessment of ballast water compliance for persons without a scientific background (e.g., ship engineers, mates, ballast water inspectors). The newly developed ATP assay, called “the P-BAC ATP assay,” was tested against the traditional boiling Tris ATP assay and a 2nd generation ATP assay.
From this project, I concluded that the traditional Tris ATP assay underestimated ATP concentrations by 2 to 4-fold in various natural aquatic microbial communities compared to the P-BAC ATP assay. When compared to the 2nd generation ATP kit, P-BAC extracted comparably at times and up to 3.4-fold more ATP. Furthermore, the P-BAC ATP assay was successfully executed during full-scale shipboard treatment tests at the Golden Bear Test Facility (California Maritime Academy, CSU), by measuring the change in living biomass before and after administering the ballast water treatment.
Predicting stranding patterns of live oiled seabirds, carcass deposition, and carcass retention in Monterey Bay
Beach surveys for live and dead beachcast birds are an economical and practical way of determining seabird population health. Using long-term surveys creates a baseline mortality profile by determining the areas and time of year birds are likely to strand as well as what oceanographic factors cause the deposition and retention of seabird carcasses on beaches. I hypothesized that 1) seabird initial carcass deposition in Monterey Bay would be greater in the southern part of the bay than in the northern part due to oceanographic factors, and 2) seabird carcass retention (how long carcasses stayed on the beach) would be greater in the North Bay than the South Bay due to beach profile characteristics. I utilized BeachCOMBERS beach survey data from 2005 to 2012 to determine patterns of seabird carcass deposition and retention in Monterey Bay and obtained wind speed, wind direction, wave height, tide height, and wave height + tide height (swell impact) from buoys. A backwards multiple regression on the averaged yearly deposition (birds km-1) as affected by oceanographic factors in Monterey yielded significant effects only in the year 2011, with wind speed being the main factor. A two-way ANOVA on the percent of carcasses retained from the previous month with month and zone as independent factors yielded significant effects of both, although location (zone) had a more significant effect. Variability in deposition and retention highlighted the need for continued long-term surveys to accurately determine seabird presence and mortality in Monterey Bay.