Nitrogen uptake potential under different temperature-salinity conditions: Implications for nitrogen cycling under climate change scenarios

• As projected by climate change models, increase in sea surface temperature and precipitation in the future may alter nutrient cycling in the coastal regions due to potential changes in phytoplankton community structure and their ability to assimilate nitrogen (N) and carbon (C). An experiment simulating different temperature and salinity conditions (28 degrees C-35 ambient conditions, 28 degrees C-31, 31 degrees C-35 and 31 degrees C-31) in mesocosms containing 1000 L of coastal water from the Arabian Sea was performed and N uptake rates were measured using N-15 tracer technique on 2nd, 5th, 7th and 10th day of the experiment. The results show that, under all conditions, the total N (NO3- + NH4+) uptake rates were lower in the beginning and on the final day of the tracer experiment, while it peaked during middle, consistent with chlorophyll a concentrations. Total N uptake rate was significantly lower (p = 0.003) under ambient temperature -lower salinity condition (28 degrees C-31) than the others. This indicates that lowering of salinity in coastal regions due to excessive rainfall in the future may affect the N uptake potential of the phytoplankton, which may change the regional C and N budget.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Oceanografi, hydrologi och vattenresurser (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Oceanography, Hydrology and Water Resources (hsv//eng)

Nyckelord

Nitrogen

Uptake

Climate change

Phytoplankton

Mesocosm experiment

harmful algal blooms

arabian sea

phytoplankton community

marine-phytoplankton

indian-ocean

heterotrophic bacteria

southwest

monsoon

nitrate uptake

f-ratio

assimilation

Environmental Sciences & Ecology

Marine & Freshwater Biology

Toxicology

allister cd

1961

limnology and oceanography

v6

p237

carthy jj

1977

limnology and oceanography

v22

p996

ates of america

v105

p6668

carthy jj

1972

limnology and oceanography

v17

p371

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