Abstract
Increasing seawater temperatures and CO2 levels associated with climate change affect the shallow marine ecosystem function. In this study, the effects of elevated seawater temperature and partial pressure of CO2 (pCO2) on subtropical sediment systems of mangrove, seagrass, and coral reef lagoon habitats of Okinawa, Japan, were examined. Sediment and seawater from each habitat were exposed to four pCO2-temperature treatments, including ambient pCO2- ambient temperature, ambient pCO2-high temperature (ambient temperature + 4°C), high pCO2 (936 ppm)-ambient temperature, and high pCO2-high temperature. Parameters including primary production, nutrient flux, pigment content, photosynthetic community composition, and bacterial abundance were examined. Neither high temperature nor high pCO2 alone impacted mangrove and seagrass sediment primary production significantly (Tukey’s test, P > 0.05). However, the combined stress significantly (Tukey’s test, P 0.05) under the combined stress, suggesting that heterotrophic processes were less affected by the combined stress than autotrophic processes. In summary, mangrove and seagrass sediments minimize the negative impacts of elevated temperature and pCO2 via increased primary production and carbon storage. Lagoonal sediments also act as a carbon sink under temperature and ocean acidification stress.
Highlights
The of marine ecosystems in mitigating the impacts of climate change has generated considerable interest owing to the capacity of these ecosystems to trap and sequester carbon (Mcleod et al, 2011; Miyajima et al, 2015; Ricart et al, 2015)
Shallow marine ecosystems are currently subjected to a combination of global and regional stressors, few experimental studies have examined shallow benthic areas to understand the consequences of increased temperature and ocean acidification (OA) (Connell et al, 2013; Johnson et al, 2013)
The combined impact of increased temperature and pCO2 associated with climate change differs significantly from the impact of individual stressors, and can result in nonlinear effects and unexpected ecological patterns (Segner et al, 2014)
Summary
The of marine ecosystems in mitigating the impacts of climate change has generated considerable interest owing to the capacity of these ecosystems to trap and sequester carbon (Mcleod et al, 2011; Miyajima et al, 2015; Ricart et al, 2015). Tidal salt marshes, seagrass beds, and coral reefs are key ecosystems that serve important roles in protecting coastal communities worldwide from storm surges, sea level rise, sediment runoff, and food insecurity (Beck et al, 2001; Mumby, 2006; Barbier et al, 2011; Sifleet et al, 2011; Cullen-Unsworth and Unsworth, 2013; Robertson and Alongi, 2013) These ecosystems help to mitigate the effects of environmental change (e.g., increasing atmospheric and oceanic CO2 and temperature) via carbon sequestration, and the storage of atmospheric and seawater carbon (Duarte et al, 2005, 2010; Bouillon et al, 2008; Kennedy et al, 2010; Donato et al, 2012; Pendleton et al, 2012; Chmura, 2013). While some studies have suggested that many marine autotrophs are insensitive to changes in pCO2 (Engel et al, 2007), others have revealed that some seagrasses (Zimmerman et al, 1997), macroalgae (Gao et al, 1993), microalgae (Kayanne et al, 2005), diatoms, coccolithophorids (Riebesell et al, 2000; Zondervan et al, 2001; Casareto et al, 2009), and cyanobacteria (Qiu and Gao, 2002) exhibit high rates of photosynthesis under elevated pCO2 conditions (Delille et al, 2005)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
