Coral reefs are known to have extremely high rates of primary production. However, common geochemical methods for determining bulk rates of reef metabolism cannot distinguish which organisms are responsible for primary production. Here we used a “bottom‐up” approach to estimate the contribution of diverse primary producers including hard corals, octocorals, and algae to gross primary production on coral reefs by scaling up tax...

Ocean acidification and changing sea surface temperatures stand to affect the interactions of corals and their Symbiodinium symbionts with regard to the inorganic carbon used for photosynthesis. However, there have been few investigations on the availability of dissolved inorganic carbon (DIC) for algal symbionts in hospite. This study compared the DIC‐associated photosynthetic kinetic parameters of three Caribbean corals and...

Due to the ongoing effects of climate change, phytoplankton are likely to experience enhanced irradiance, more reduced nitrogen, and increased water acidity in the future ocean. Here, we used Thalassiosira pseudonana as a model organism to examine how phytoplankton adjust energy production and expenditure to cope with these multiple, interrelated environmental factors. Following acclimation to a matrix of irradiance, nitrogen...

Summary In the pelagic environment, iron is a scarce but essential micronutrient. The iron acquisition capabilities of selected marine bacteria have been investigated, but the recent proliferation of marine prokaryotic genomes and metagenomes offers a more comprehensive picture of microbial iron uptake pathways in the ocean. Searching these data sets, we were able to identify uptake mechanisms for Fe 3+ , Fe 2+ and iron chelat...

In the high‐nutrient, low‐chlorophyll waters of the Gulf of Alaska, microcosm manipulation experiments were used to assess the effect of CO 2 on growth and primary production under iron‐limited and iron‐replete conditions. As expected, iron had a strong effect on growth and photosynthesis. A modest and variable stimulation of growth and biomass production by CO 2 (high CO 2 : 77–122 Pa; low CO 2 : 11‐17 Pa) was observed under...

The roles of iron and light as limiting and colimiting factors for phytoplankton growth in subsurface chlorophyll maxima (SCMs) were investigated in mesotrophic to oligotrophic waters of the Southern California Bight and the eastern tropical North Pacific using microcosm manipulation experiments. Phytoplankton responses indicative of iron‐light colimitation were found at several SCMs underlying macronutrient‐limited surface wa...

Processes influencing phytoplankton bloom development in the southern Drake Passage were studied using shipboard iron‐enrichment incubations conducted across a surface chlorophyll gradient near the Antarctic Peninsula, in a region of water mass mixing. Iron incubation assays showed that Antarctic Circumpolar Current (ACC) waters were severely iron limited, while shelf waters with high ambient iron concentrations (1–2 nmol L −1...

Previous studies have shown that watersheds with significant human development (i.e., urban and agricultural land use) generally have higher concentrations and fluxes of dissolved inorganic nitrogen (DIN) in comparison to less‐developed or forested watersheds. However, the impact of watershed development on dissolved organic nitrogen (DON) concentrations in drainage waters has received little attention. We present data from 39...