Topic
Water column
About: Water column is a research topic. Over the lifetime, 13706 publications have been published within this topic receiving 496626 citations.
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TL;DR: It is demonstrated that eelgrass growth is affected both by sediment nitrogen resources and the higher order effects of epiphytes and their control by Idotea resecata.
Abstract: Although the growth of eelgrass (Zostera marina) is controlled by resources as well as higher order interactions with epiphytes and their herbivores, these constraints rarely are considered together. The ability to utilize both water column and sediment nutrient sources in a complex habitat may provide eelgrass with a partial release from nutrient competition with epiphytes that have more efficient uptake kinetics and can reduce eelgrass growth, particularly in eutrophic habitats. We investigated the relative effects of dissolved inorganic nitrogen in the water column vs. the sediments, and herbivory by the common isopod Idotea resecata, on eelgrass growth and epiphyte biomass in an intertidal eelgrass bed in Padilla Bay, Washington. In the field, we fertilized the sediments and/or the water column with ammonium and measured eelgrass growth and epiphyte biomass. We also monitored epiphyte biomass and water column nutrient concentrations and cen- sused isopod densities. Laboratory experiments focused on the effects of I. resecata, fer- tilization of the water column and sediments, and depletion of sediment nutrients on eelgrass growth and epiphyte biomass. Most simply, we hypothesized that epiphytes would respond positively to increased water column nutrients as eelgrass would to increased sediment nutrients, and that herbivory on epiphytes could mitigate deleterious effects of epiphytes on eelgrass. We demonstrated that eelgrass growth is affected both by sediment nitrogen resources and the higher order effects of epiphytes and their control by Idotea resecata. During our field experiments, growth of eelgrass leaves tended to increase in response to sediment
249 citations
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TL;DR: This article examined the processes which affect the relationship between foraminiferal Mg/Ca and δ18O and found that Globigerinoides saccculifer calcifies over a relatively large range of water depth and that this is apparent in their Mg content.
Abstract: Using bathymetric transects of surface sediments underlying similar sea surface temperatures but exposed to increasing dissolution, we examined the processes which affect the relationship between foraminiferal Mg/Ca and δ18O. We found that Globigerinoides saccculifer calcifies over a relatively large range of water depth and that this is apparent in their Mg content. On the seafloor, foraminiferal Mg/Ca is substantially altered by dissolution with the degree of alteration increasing with water depth. Selective dissolution of the chamber calcite, formed in surface waters, shifts the shell's bulk Mg/Ca and δ18O toward the chemistries of the secondary crust acquired in colder thermocline waters. The magnitude of this shift depends on both the range of temperatures over which the shell calcified and the degree to which it is subsequently dissolved. In spite of this shift the initial relationship between Mg/Ca and δ18O, determined by their temperature dependence, is maintained. We conclude that paired measurements of δ18O and Mg/Ca can be used for reconstructing δ18Owater, though care must be taken to determine where in the water column the reconstruction applies.
248 citations
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TL;DR: In this paper, trace metal clean techniques were used to sample Hawaii Ocean Time-series (HOT) station ALOHA on seven occasions between November 1998 and October 2002, and full water column profile samples were obtained; on the other four occasions, surface and near surface euphotic zone profiles were obtained.
247 citations
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TL;DR: Rhenium (Re) is one of a suite of elements (including uranium and molybdenum) that display conservative behavior in seawater and are enriched in anoxic sediments as discussed by the authors.
245 citations
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TL;DR: The distribution profiles of these contaminants in water and sediments suggest that there are a number of sources contributing to total contaminant burden in the bay, including soil runoffs, wastewater discharges, sewage outfalls and shipping activites.
245 citations