Oceanographic and meteorological conditions during a ship mooring force study /

"August 1985."

The chaetognatha of the Eastropic Expedition, with notes as to their possible value as indicators of hydrographic conditions

ENGLISH: The purpose of this study was to investigate the possibility that certain species of Chaetognatha found in Eastern Tropical Pacific waters can serve as biological indicators of oceanographic features. "Indicator" organisms have been found useful in identifying water types, in tracing the pattern of current systems, and in tracing the origin of moving water masses. To be of use in this type of study, the organisms must be sufficiently abundant to be readily sampled, and easily identified to species; they must also, at least partially, fulfill the additional requisites listed and discussed by Sverdrup, Johnson, and Fleming (1942, pp. 866-867). Among several groups of organisms fulfilling these requirements are the Chaetognatha. Specimens of this group of animals occurred in large numbers in the plankton samples used for this study. The works of Thomson (1947), Fraser (1942), Ritter-Zahony (1911), and Sund (1959) were used for identification. SPANISH: El objetivo de este estudio ha sido el de investigar la posibilidad de utilizar ciertas especies de quetognatos encontrados en el Pacífico Oriental Tropical como indicadoras biológicas de características oceanográficas. Organismos "indicadores" fueron encontrados útiles para la identificación de tipos de agua, el trazado del régimen de los sistemas de corrientes y la determinación del origen de masas de agua en movimiento. Para servir a este tipo de estudios, los organismos deben ser lo suficientemente abundantes como para ser fácilmente muestreados e identificados hasta la especie; también deben satisfacer, por lo menos parcialmente, los requerimientos indicados y discutidos par Sverdrup, Johnson y Fleming (1942, pags. 866-867).

Oceanographic variability at Clipperton Atoll since the 1880s: stable isotopic evidence from massive corals [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Clipperton Atoll (10°18'N, 109°13'W), lies within the eastern Pacific elongated warm water pool centered at 10°N and is situated at the boundary of the North Equatorial Counter-Current (NECC) and westward-flowing eddy currents moving away from Central America. ... Fifteen coral cores were collected from massive heads of Porites lobata in April 1994 for the purpose of reconstructing oceanographic and climatic conditions at this open ocean site in the eastern Pacific.

Ecology of the common octopus "Octopus vulgaris" (Cuvier, 1797) in the Atlantic Iberian coast : life cycle strategies under different oceanographic regimes

Tese de doutoramento, Biologia (Biologia Marinha e Aquacultura), Universidade de Lisboa, Faculdade de Ciências, 2015

Regional differences in the spatial and temporal heterogeneity of oceanographic habitat used by Steller sea lions

Over the past three decades, the decline and altered spatial distribution of the western stock of Steller sea lions (Eumetopias jubatus) in Alaska have been attributed to changes in the distribution or abundance of their prey due to the cumulative effects of fisheries and environmental perturbations. During this period, dietary prey occurrence and diet diversity were related to population decline within metapopulation regions of the western stock of Steller sea lions, suggesting that environmental conditions may be variable among regions. The objective of this study, therefore, was to examine regional differences in the spatial and temporal heterogeneity of oceanographic habitat used by Steller sea lions within the context of recent measures of diet diversity and population trajectories. Habitat use was assessed by deploying satellite-depth recorders and satellite relay data loggers on juvenile Steller sea lions (n = 45) over a five-year period (2000–2004) within four regions of the western stock, including the western, central, and eastern Aleutian Islands, and central Gulf of Alaska. Areas used by sea lions during summer months (June, July, and August) were demarcated using satellite telemetry data and characterized by environmental variables (sea surface temperature [SST] and chlorophyll a [chl a]), which possibly serve as proxies for environmental processes or prey. Spatial patterns of SST diversity and Steller sea lion population trends among regions were fairly consistent with trends reported for diet studies, possibly indicating a link between environmental diversity, prey diversity, and distribution or abundance of Steller sea lions. Overall, maximum spatial heterogeneity coupled with minimal temporal variability of SST appeared to be beneficial for Steller sea lions. In contrast, these patterns were not consistent for chl a, and there appeared to be an ecological threshold. Understanding how Steller sea lions respond to measures of environmental heterogeneity will ultimately be useful for implementing ecosystem management approaches and developing additional conservation strategies.

Influence of Surface Oceanographic Variability on Abundance of the Western Winter-Spring Cohort of Neon Flying Squid Ommastrephes Bartramii in the Nw Pacific Ocean

Abundance of the Ommastrephes bartramii winter-spring cohort fluctuated greatly from 1995 to 2004. To understand how abundance was influenced by sea surface conditions, we examined the variations in the proportion of thermal habitats with favourable sea surface temperature (SST). The SST data of both the spawning and feeding grounds were used to calculate the monthly proportion of favourable-SST areas (PFSSTA). Catch per fishing day per fishing boat (catch per unit effort, CPUE) of the Chinese mainland squid-jigging fleet was used as squid abundance index. The relationships between CPUE and monthly PFSSTA at spawning and feeding grounds were analyzed, and the relationship between CPUE and selected PFSSTA was quantified with a multiple linear regression model. Results showed that February PFSSTA at the spawning ground and August to November PFSSTA at the feeding ground could account for about 60% of the variability in O. bartramii abundance between 1995 and 2004, that February was the most important period influencing squid recruitment during the spawning season, and that feeding ground PFSSTA during the fishing season would influence CPUE by causing squid to aggregate. Our forecast model was found to perform well when we compared the model-predicted CPUEs and the average CPUEs observed during August to November in 2005 and 2006 from the Chinese squid-jigging fishery.

Environmental conditions and habitats of GOS sites and bottle data of HOT-ALOHA station

The Global Ocean Sampling (GOS) expedition is currently the largest and geographically most comprehensive metagenomic dataset, including samples from the Atlantic, Pacific, and Indian Oceans. This study makes use of the wide range of environmental conditions and habitats encompassed within the GOS sites in order to investigate the ecological structuring of bacterial and archaeal taxon ranks. Community structures based on taxonomically classified 16S ribosomal RNA (rRNA) gene fragments at phylum, class, order, family, and genus rank levels were examined using multivariate statistical analysis, and the results were inspected in the context of oceanographic environmental variables and structured habitat classifications. At all taxon rank levels, community structures of neritic, oceanic, estuarine biomes, as well as other exotic biomes (salt marsh, lake, mangrove), were readily distinguishable from each other. A strong structuring of the communities with chlorophyll a concentration and a weaker yet significant structuring with temperature and salinity were observed. Furthermore, there were significant correlations between community structures and habitat classification. These results were used for further investigation of one-to-one relationships between taxa and environment and provided indications for ecological preferences shaped by primary production for both cultured and uncultured bacterial and archaeal clades.

Oceanic conditions off Northeastern Brazil, February-March and October-November 1966

"CG 373-34."

Dinocyst assemblage constraints on oceanographic and atmospheric processes in the eastern equatorial Atlantic over the last 44 kyr

A new 44 kyr long record of dinoflagellate (phytoplanktonic organisms) cysts (dinocysts) is presented from a marine sediment core collected on the Congolese margin with the aim of reconstructing past hydrological changes in the equatorial eastern Atlantic Ocean since Marine Isotopic Stage (MIS) 3. Our high-resolution dinocyst record indicates that significant temperature and moisture variations occurred across the glacial period, the last deglaciation and the Holocene. The use of specific dinocyst taxa, indicative of fluvial, upwelling and Benguela Current past environments for instance, provides insights into the main forcing mechanisms controlling palaeohydrological changes on orbital timescales. In particular, we are able, for the last 44 kyr, to correlate fluvial-sensitive taxa to monsoonal mechanisms related to precession minima–obliquity maxima combinations. While upwelling mechanisms appear as the main drivers for dinoflagellate productivity during MIS 2, dissolved nutrient-enriched Congo River inputs to the ocean also played a significant role in promoting dinoflagellate productivity between approximately 15.5 and 5 ka BP. Finally, this high-resolution dinocyst study permits us to precisely investigate the suborbital timing of the last glacial–interglacial termination, including an atypical warm and wet oceanic LGM signature, northern high-latitude abrupt climate change impacts in the equatorial eastern Atlantic, as well as a two-step decrease in moisture conditions during the Holocene at around 7–6 and 4–3.5 ka BP.

Hydrazine-hydrate intercalated halloysite under controlled-rate thermal analysis conditions

The thermal behaviour of halloysite fully expanded with hydrazine-hydrate has been investigated in nitrogen atmosphere under dynamic heating and at a constant, pre-set decomposition rate of 0.15 mg min-1. Under controlled-rate thermal analysis (CRTA) conditions it was possible to resolve the closely overlapping decomposition stages and to distinguish between adsorbed and bonded reagent. Three types of bonded reagent could be identified. The loosely bonded reagent amounting to 0.20 mol hydrazine-hydrate per mol inner surface hydroxyl is connected to the internal and external surfaces of the expanded mineral and is present as a space filler between the sheets of the delaminated mineral. The strongly bonded (intercalated) hydrazine-hydrate is connected to the kaolinite inner surface OH groups by the formation of hydrogen bonds. Based on the thermoanalytical results two different types of bonded reagent could be distinguished in the complex. Type 1 reagent (approx. 0.06 mol hydrazine-hydrate/mol inner surface OH) is liberated between 77 and 103°C. Type 2 reagent is lost between 103 and 227°C, corresponding to a quantity of 0.36 mol hydrazine/mol inner surface OH. When heating the complex to 77°C under CRTA conditions a new reflection appears in the XRD pattern with a d-value of 9.6 Å, in addition to the 10.2 Ĺ reflection. This new reflection disappears in contact with moist air and the complex re-expands to the original d-value of 10.2 Å in a few h. The appearance of the 9.6 Å reflection is interpreted as the expansion of kaolinite with hydrazine alone, while the 10.2 Å one is due to expansion with hydrazine-hydrate. FTIR (DRIFT) spectroscopic results showed that the treated mineral after intercalation/deintercalation and heat treatment to 300°C is slightly more ordered than the original (untreated) clay.