Marine Biology Department (MARB)
Permanent URI for this collectionhttps://hdl.handle.net/1969.3/28243
The focus of this department is biological science with an ocean or estuarine emphasis
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Browsing Marine Biology Department (MARB) by Author "Rowe, Gilbert T."
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Item Benthic biomass in the Pisco, Peru upwelling(1971-02) Rowe, Gilbert T.Quantitative benthic samples were taken off Peru in and adjacent to the Pisco upwelling in an attempt to assess the effects of extremes in productivity and dissolved oxygen on the distribution of biomass (organic cabon). The macrofauna was combused to organic carbon (less the carbonate fraction) to allow direct comparisons with the production of organic carbon at the surface and its distribution in the water column and sediments. Similar techniques were employed in the Gulf of Mexico previously (Rowe and Menzel, 1970), and it is hoped comparisons of the two sets of data contrasting regions of low and high proudctivity will give some insights into the nature of the movement of organic energy from its source through the water column to the bottom.Item Benthic production and processes off Baja California, Northwest Africa and Peru: a classification of benthic subsystems in upwelling ecosystems(Instituto de Investigaciones Pesqueras., 1985) Rowe, Gilbert T.Estimates of the standing stocks, secondary production and metabolism of the benthos have been compared in the coastal upwelling ecosystems off northwest Africa, Baja California, and southern Peru. Northwest Africa is characterized by shelf break upwelling and as a result standing stocks, macrobenthic production and sediment organic matter are highest out at the shelf-slope boundary. Sediment microbial activity and biomass on the other hand are highest nearshore in the dynamic zone where aeolian silt and sand are being blown into the sea from the Sahara Desert. Baja California is dominatd by the red crab Pleuroncodes planipes, having high rates of growth and metabolic utilization of organic matter, both on bottom and in the water. Peru benthos and metabolism are very different from the above areas because of the low oxygen concentrations in the bottom water. Organic matter is far higher in the sediment and heterotrophic metabolism is principally anaerobic rather than aerobic. A normal offshore benthic fauna is replaced by a mat of sulfur bacteria with unknown production and metabolic rates. Benthic subsystems in upwelling ecosystems can be placed in two categories: those overloaded with organic matter, depleted of oxygen and dominated by sulfate reduction and those that are are not overloaded and remain aerobic. Peru and southwest Africa typify overloaded systems whereas NW Africa and Baja California are examples of aerobic systems. Although benthic metabolism and inorganic nutrient regeneration are high in both types of subsystems, all upwelling ecosystems, with their dynamic open boundaries, export organic particulate matter and import inorganic nutrients at rates that are far in excess of that consumed or produced by benthic metabolism.Item Early diagenesis of organic matter in sediments off the coast of Peru(1985) Rowe, Gilbert T.; Howarth, RobertMeasured rates of SO4 and NH4 were used to estimate organic matter regeneration from the sediments in an area of intense upwelling and high primary production off Peru. While the estimated rates of remineralization were high compared to other ecosystems at comparable water depths, this source of nutrients appeared to be on the order of 10% of the phytoplankton demand. Disparities between measured vs modelled estimates of sulfate reduction appear to be a function of the concentration gradients across the sediment-water interface and mixing by biological and physical processes. The suite of measurements allowed estimation of 'irrigation' and an 'irrigation' coefficient at the nearshore station where measured rates were considerably above those estimated from the pore water sulfate gradient.