TY - JOUR
T1 - NItrogen dynamics and phytoplankton community structure: the role of organic nutrients
AU - Moschonas, Grigorios
AU - Gowen, Richard
AU - Paterson, Ruth
AU - Mitchell, Elaine
AU - Stewart, Brian
AU - Mcneill, Sharon
AU - Glibert, Patricia
AU - Davidson, Keith
N1 - © The Authors 2017, published by Springer International Publishing AG
PY - 2017/6/14
Y1 - 2017/6/14
N2 - Dissolved organic nitrogen (DON) is recognised as an important N source for phytoplankton. However, rarely has its relative importance for phytoplankton nutrition and community composition been studied comprehensively. This study, conducted in a typical Scottish fjord, representative of near-pristine coastal environments, evaluates the utilisation of DON and dissolved inorganic nitrogen (DIN) by different microbial size fractions and the relationship of phytoplankton community composition with DON and other parameters. The study demonstrated that DON was important in supporting phytoplankton throughout the yearly production cycle. The higher-than-expected urea uptake rates and large fraction of the spring bloom production supported by DON suggested that organic N not only contributes to regenerated production and to the nutrition of the small phytoplankton fraction, but can also contribute substantially to new production of the larger phytoplankton in coastal waters. Multivariate statistical techniques revealed two phytoplankton assemblages with peaks in abundance at different times of the year: a spring group dominated by Skeletonema spp., Thalassiosira spp., and Pseudo-nitzschia spp. group delicatissima; and a summer/autumn group dominated by Chaetoceros spp., Scrippsiella spp., and Pseudo-nitzschia spp. group seriata. The multivariate pattern in community composition and abundance of these taxa was significantly correlated with the multivariate pattern of DON, urea, dissolved free amino acids (DFAA), DIN, temperature, salinity, and photoperiod (as daylength), with photoperiod and urea being particularly important, suggesting both physical and chemical controls on community composition.
AB - Dissolved organic nitrogen (DON) is recognised as an important N source for phytoplankton. However, rarely has its relative importance for phytoplankton nutrition and community composition been studied comprehensively. This study, conducted in a typical Scottish fjord, representative of near-pristine coastal environments, evaluates the utilisation of DON and dissolved inorganic nitrogen (DIN) by different microbial size fractions and the relationship of phytoplankton community composition with DON and other parameters. The study demonstrated that DON was important in supporting phytoplankton throughout the yearly production cycle. The higher-than-expected urea uptake rates and large fraction of the spring bloom production supported by DON suggested that organic N not only contributes to regenerated production and to the nutrition of the small phytoplankton fraction, but can also contribute substantially to new production of the larger phytoplankton in coastal waters. Multivariate statistical techniques revealed two phytoplankton assemblages with peaks in abundance at different times of the year: a spring group dominated by Skeletonema spp., Thalassiosira spp., and Pseudo-nitzschia spp. group delicatissima; and a summer/autumn group dominated by Chaetoceros spp., Scrippsiella spp., and Pseudo-nitzschia spp. group seriata. The multivariate pattern in community composition and abundance of these taxa was significantly correlated with the multivariate pattern of DON, urea, dissolved free amino acids (DFAA), DIN, temperature, salinity, and photoperiod (as daylength), with photoperiod and urea being particularly important, suggesting both physical and chemical controls on community composition.
U2 - 10.1007/s10533-017-0351-8
DO - 10.1007/s10533-017-0351-8
M3 - Article
SP - 125
EP - 145
JO - Biogeochemistry
JF - Biogeochemistry
SN - 0168-2563
ER -