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Full-Text Articles in Marine Biology
Dinitrogen Fixation And Release Of Ammonium And Dissolved Organic Nitrogen By Trichodesmium Ims101, Margaret R. Mulholland, Deborah A. Bronk, Douglas G. Capone
Dinitrogen Fixation And Release Of Ammonium And Dissolved Organic Nitrogen By Trichodesmium Ims101, Margaret R. Mulholland, Deborah A. Bronk, Douglas G. Capone
OES Faculty Publications
Two methods used to measure dinitrogen (N2) fixation (acetylene reduction and 15N2 uptake) often result in different N2 fixation rates. Part of the discrepancy may arise from the observation that Trichodesmium can release a fraction of their recently fixed N2 as dissolved organic nitrogen (DON) and/or ammonium (NH4 +). To resolve outstanding issues regarding N2 fixation and the production of dissolved combined nitrogen (N) by Trichodesmium, we conducted a comprehensive analysis of N2 fixation and the production of DON and NH4+ in cultures of Trichodesmium IMS101. We performed …
Light Dependence Of Selenium Uptake By Phytoplankton And Implications For Predicting Selenium Incorporation Into Food Webs, Stephen B. Baines, Nicholas S. Fisher, Martina A. Doblin, Gregory A. Cutter, Lynda S. Cutter, Brian Cole
Light Dependence Of Selenium Uptake By Phytoplankton And Implications For Predicting Selenium Incorporation Into Food Webs, Stephen B. Baines, Nicholas S. Fisher, Martina A. Doblin, Gregory A. Cutter, Lynda S. Cutter, Brian Cole
OES Faculty Publications
The potentially toxic element selenium is first concentrated from solution to a large but highly variable degree by algae and bacteria before being passed on to consumers. The large loads of abiotic and detrital suspended particles often present in rivers and estuaries may obscure spatial and temporal patterns in Se concentrations at the base of the food web. We used radiotracers to estimate uptake of both selenite (Se(IV)) and C by intact plankton communities at two sites in the Sacramento/San Joaquin River Delta. Our goals were to determine (1) whether C and Se(IV) uptake were coupled, (2) the role of …
Does Antarctic Krill Employ Body Shrinkage As An Overwintering Strategy?, Se-Jong Ju, H. Rodger Harvey, H. C. Shinn, Y. Kim, S. H. Kang
Does Antarctic Krill Employ Body Shrinkage As An Overwintering Strategy?, Se-Jong Ju, H. Rodger Harvey, H. C. Shinn, Y. Kim, S. H. Kang
OES Faculty Publications
To determine if Antarctic krill employ body shrinkage as one of its overwintering mechanisms in the field, Euphausia superba and Euphausia crystallorophias were collected during fall and winter in and around Marguerite Bay through US Southern Ocean GLOBEC field programs during fall and winter 2001 and 2002. The relationships between the body length and weight of both krill species were exponentially correlated with no significant differences between the two species (p>0.05). The ratio between eye diameter and body length of individual krill was examined in an expectation that it could be used as an indicator of the body shrinkage …
Advection, Krill, And Antarctic Marine Ecosystems, Eileen E. Hofmann, Eugene J. Murphy
Advection, Krill, And Antarctic Marine Ecosystems, Eileen E. Hofmann, Eugene J. Murphy
CCPO Publications
Advective processes are recognized as being important in structuring and maintaining marine ecosystems. In the Southern Ocean advective effects are perhaps most clearly observed because the Antarctic Circumpolar Current (ACC) provides a connection between most parts of the system, including open ocean and continental shelf regions. The ACC also provides a mechanism for large-scale transport of plankton, such as Antarctic krill (Euphousia superba Dana), which is an important component of the Southern Ocean food web. This overview provides a summary of recent observational and modelling results that consider the importance of advection to the Southern Ocean ecosystem and, in particular, …