Aquatic primary productivity produces oxygen (O2) and consumes carbon dioxide (CO2) in a ratio of ~1.2. However, in aquatic ecosystems, dissolved CO2concentrations can be low, potentially limiting primary productivity. Here, results show that a large drainage basin maintains its highest levels of gross primary productivity (GPP) when dissolved CO2is diminished or undetectable due to photosynthetic uptake. Data show that, after CO2is depleted, bicarbonate, an ionized form of inorganic carbon, supports these high levels of productivity. In fact, outputs from a process‐based model suggest that bicarbonate can support up to ~58% of GPP under the most productive conditions. This is the first evidence that high levels of aquatic GPP are sustained in a riverine drainage network despite CO2depletion, which has implications for freshwater ecology, biogeochemistry, and isotopic analysis.
It is widely hypothesized that noncalcifying macroalgae will be more productive and abundant in increasingly warm and acidified oceans. Macroalgae vary greatly in the magnitudes and interactions of responses of photosynthesis and growth to multiple stressors associated with climate change. A knowledge gap that exists between the qualitative “macroalgae will benefit” hypothesis and the variable outcomes observed is regulation of physiological mechanisms that cause variation in the magnitudes of change in primary productivity, growth, and their covariation. In this context, we developed a model to quantitatively describe physiological responses to coincident variation in temperature, carbonate chemistry and light supply in a representative bicarbonate‐using marine macroalga. The model is based on
- NSF-PAR ID:
- 10455472
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Limnology and Oceanography
- Volume:
- 65
- Issue:
- 10
- ISSN:
- 0024-3590
- Page Range / eLocation ID:
- p. 2541-2555
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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