Productivity and Respiration Steve Lohrenz (Leader), David Munro (Rappoteur), Galen McKinley, Francis Wilkerson, Francisco Chavez, Jeremy Mathis, Dick Dugdale, Laurie Juranek, Peter Griffith, Cindy Chandler

What are the key processes and sub- processes involved? What is the value of productivity/respiration to regional coastal C budgets? Prod/resp provide understanding of processes mediating changes Prod/resp provide understanding of processes mediating changes E.g., Equatorial vs coastal upwelling: P/R balance results in much different air-sea C flux E.g., Equatorial vs coastal upwelling: P/R balance results in much different air-sea C flux Necessary to predict future changes to C budgets due to climate change/ocean acidification Necessary to predict future changes to C budgets due to climate change/ocean acidification We don’t understand respiration as well as we need to We don’t understand respiration as well as we need to Decoupling of productivity and respiration Decoupling of productivity and respiration Both horizontally and vertically Both horizontally and vertically E.g., Great Lakes-PP homogenous, Resp is heterogeneous E.g., Great Lakes-PP homogenous, Resp is heterogeneous Understanding respiration requires knowledge of the whole system, whereas PP is restricted to the photic zone Understanding respiration requires knowledge of the whole system, whereas PP is restricted to the photic zone Key aspect of coastal systems in terms of carbon balance is the episodic variability of the involved processes Key aspect of coastal systems in terms of carbon balance is the episodic variability of the involved processes

Parameters Gross Primary Production (GPP) Gross Primary Production (GPP) Net Primary Production (NPP) Net Primary Production (NPP) Net Ecosystem Production (NEP) or net community production (NCP) Net Ecosystem Production (NEP) or net community production (NCP) Respiration Respiration Autotrophic vs heterotrophic Autotrophic vs heterotrophic Allochthonous vs autochthonous Allochthonous vs autochthonous Export production: vertical or horizontal Export production: vertical or horizontal Partitioning of carbon fixed by NPP into pools and trophic groups Partitioning of carbon fixed by NPP into pools and trophic groups DOC, POC, and higher trophic levels DOC, POC, and higher trophic levels Resolving DOC microbial processes Resolving DOC microbial processes Different DOC pools: refractory, labile Different DOC pools: refractory, labile Microbial C pump Microbial C pump Mixed layer depths and water column structure Mixed layer depths and water column structure There is a need to prioritize the above parameters There is a need to prioritize the above parameters

Regulatory mechanisms Surface entrainment of nutrients Surface entrainment of nutrients Fe and Silicate Fe and Silicate Importance of feedbacks as a result of climate change/ocean acidification Importance of feedbacks as a result of climate change/ocean acidification Temp effects on respiration Temp effects on respiration

Methods/measurements Remote sensing Remote sensing How do we use measurements to tweak satellite algorithms? How do we use measurements to tweak satellite algorithms? Short term bottle incubations Short term bottle incubations Budget-based approaches Budget-based approaches Direct gas/and isotope tracers Direct gas/and isotope tracers Nutrient and DIC drawdown Nutrient and DIC drawdown Dependent on accurate representation of physical circulation Dependent on accurate representation of physical circulation Autonomous vehicles/moored sensors Autonomous vehicles/moored sensors Gliders – huge coverage in time and space Gliders – huge coverage in time and space FRRF and other optical approaches FRRF and other optical approaches Photosynthesis and irradiance approaches for productivity Photosynthesis and irradiance approaches for productivity How do we measure respiration? How do we measure respiration? Chamber measurements Chamber measurements Microsensors/microelectrodes for dissolved oxygen Microsensors/microelectrodes for dissolved oxygen

Can individual measurements be scaled up? Models can be used to scale up from short term/small spatial scales to larger scales Models can be used to scale up from short term/small spatial scales to larger scales Must also scale measurements across key boundaries: benthic/water column and offshore/coastal/estuarine Must also scale measurements across key boundaries: benthic/water column and offshore/coastal/estuarine

Model parameterization How well are the processes parameterized for models? How well are the processes parameterized for models? Currently just primary production, respiration, export production Currently just primary production, respiration, export production Models can be made to capture observations and, to some degree, their variability in space and time. But, because we lack fundamental mechanistic understandings, regional tuning is required to fit a particular system. Models can be made to capture observations and, to some degree, their variability in space and time. But, because we lack fundamental mechanistic understandings, regional tuning is required to fit a particular system. Tuning has many degrees of freedom. Tuning has many degrees of freedom. Getting some measure of carbon cycling right (e.g. surface pCO2, CHL) can be achieved with many different underlying "carbon cycles" in a system. Getting some measure of carbon cycling right (e.g. surface pCO2, CHL) can be achieved with many different underlying "carbon cycles" in a system. Parameterizations are only as good as the data, and its synthesized understanding, on which they are based. Parameterizations are only as good as the data, and its synthesized understanding, on which they are based. Rate measurements are more valuable than stocks (e.g., chl, C). Rate measurements are more valuable than stocks (e.g., chl, C).