Warming intensify CO2 flux and nutrient release from algal wrack subsidies on sandy beaches

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http://hdl.handle.net/10138/309459

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Lastra , M , Lopez , J & Rodil , I F 2018 , ' Warming intensify CO2 flux and nutrient release from algal wrack subsidies on sandy beaches ' , Global Change Biology , vol. 24 , no. 8 , pp. 3766-3779 . https://doi.org/10.1111/gcb.14278

Title: Warming intensify CO2 flux and nutrient release from algal wrack subsidies on sandy beaches
Author: Lastra, Mariano; Lopez, Jesus; Rodil, Ivan F.
Contributor: University of Helsinki, Tvärminne Zoological Station
Date: 2018-08
Language: eng
Number of pages: 14
Belongs to series: Global Change Biology
ISSN: 1354-1013
URI: http://hdl.handle.net/10138/309459
Abstract: Algal wrack subsidies underpin most of the food web structure of exposed sandy beaches and are responsible of important biogeochemical processes that link marine and terrestrial ecosystems. The response in decomposition of algal wrack deposits to global warming has not been studied in ocean-exposed sandy beaches to date. With this aim, passive open top chambers (OTCs) were used to increase soil temperature within the range predicted by the IPCC for western Europe (between 0.5 and 1.5 degrees C), following the hypothesis that the biogeochemical processing of macroalgal wrack subsidies would accelerate in response to temperature increase. The effect of temperature manipulation on three target substrates: fresh and aged macroalgae, and bare sand, was tested. Results indicated that a small warming (<0.5 degrees C) affected the wrack decomposition process through traceable increases in soil respiration through CO2 flux, inorganic nutrients within the interstitial environment (N and P), sediment organic contents measured through the amount of proteins and microbial pool through the total soil DNA. The different responses of soil variables in the studied substrates indicated that the decomposition stage of stranded macroalgae influences the biogeochemical processing of organic matter in sandy beaches. Thus, CO2 fluxes, releases of organic and inorganic nutrients and microbial activity intensify in aged wrack deposits. Our results predict that expected global warming will increase the release of inorganic nutrients to the coastal ocean by 30% for the N (21 Gg/year) and 5.9% for P (14 Gg/year); that increase for the flow of C to the atmosphere as CO2 was estimated in 8.2% (523 Gg/year). This study confirms the key role of sandy beaches in recycling ocean-derived organic matter, highlighting their sensitivity to a changing scenario of global warming that predicts significant increases in temperature over the next few decades.
Subject: CO2
DNA
global warming
nutrients
open top chambers
organic enrichment
wrack decay
NITRATE REDUCTASE-ACTIVITY
EASTERN ENGLISH-CHANNEL
OPEN-TOP CHAMBERS
SOIL RESPIRATION
MICROBIAL COMMUNITIES
TEMPERATURE RESPONSE
DETACHED MACROPHYTES
INTERTIDAL SEDIMENTS
OCEAN ACIDIFICATION
SOUTHERN CALIFORNIA
1172 Environmental sciences
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