Editing IPCC:AR6/WGII/Chapter-5 (section)

=== 5.9.1 Observed Impacts ===

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Marine aquaculture food production is being impacted directly and indirectly by climate change ( ''high confidence'' ) ( [[#Bindoff--2019|Bindoff et al., 2019]] ). Ocean pH and oxygen levels are declining, whereas global warming, sea level rise and extreme events are increasing (Cross-Chapter Box SLR in Chapter 3, [[#Canadell--2021|Canadell et al., 2021]] ; [[#Eyring--2021|Eyring et al., 2021]] ; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ; Lee et al., 2021;). Marine heatwaves have been increasing in both incidence and longevity over the past century ( [[#Frolicher--2018|Frolicher and Laufkotter, 2018]] ; [[#Oliver--2018|Oliver et al., 2018]] ; [[#Bricknell--2021|Bricknell et al., 2021]] ), with productivity consequences for marine aquaculture (mariculture), carbon sequestration and local species extinctions ( ''high confidence'' ) ( [[#Weatherdon--2016|Weatherdon et al., 2016]] ; [[#Smale--2019|Smale et al., 2019]] ). Temperature increases related to El Niño climatic oscillations have caused mass fish mortalities either through warming waters (e.g., Pacific threadfin in Hawaii ( [[#McCoy--2017|McCoy et al., 2017]] )) or associated HABs (e.g., 12% loss of Atlantic salmon as well as other fish and shellfish in Chile in 2016, with estimated USD 800 million in losses ( ''high confidence'' ) ( [[#Clement--2016|Clement et al., 2016]] ; [[#Apablaza--2017|Apablaza et al., 2017]] ; [[#Leon-Munoz--2018|Leon-Munoz et al., 2018]] ; [[#Trainer--2020|Trainer et al., 2020]] )). Increases in sea lice parasite infestations on salmon are related to higher salinity and warmer waters ( ''medium confidence'' ) ( [[#Groner--2016|Groner et al., 2016]] ; [[#Soto--2019|Soto et al., 2019]] ). Ocean acidification is having negative impacts on the sustainability of mariculture production ( ''high confidence'' ) ( [[#Bindoff--2019|Bindoff et al., 2019]] ), with observed impacts on shellfish causing significant production and economic losses for regions, estimated at losses of nearly USD 110 million by 2015 in the Pacific Northwest ( [[#Barton--2015|Barton et al., 2015]] ; [[#Ekstrom--2015|Ekstrom et al., 2015]] ; [[#Waldbusser--2015|Waldbusser et al., 2015]] ; [[#Zhang--2017b|Zhang et al., 2017b]] ; [[#Doney--2020|Doney et al., 2020]] ). Ocean oxygen levels are declining due to climate change ( [[#Hoegh-Guldberg--2018|Hoegh-Guldberg et al., 2018]] ; [[#IPCC--2021|IPCC, 2021]] ), and decreased oxygen (hypoxia) has negative impacts on fish physiology ( [[#Cadiz--2018|Cadiz et al., 2018]] ; [[#Hvas--2019|Hvas and Oppedal, 2019]] ; [[#Martos-Sitcha--2019|Martos-Sitcha et al., 2019]] ; [[#Perera--2021|Perera et al., 2021]] ), fish growth, behaviour and sensitivity to concurrent stressors ( ''high confidence'' ) ( [[#Stehfest--2017|Stehfest et al., 2017]] ; [[#Abdel-Tawwab--2019|Abdel-Tawwab et al., 2019]] ).

Observed impacts on inland systems have generally been site and region specific ( ''high confidence'' ) ( [[#Hoegh-Guldberg--2018|Hoegh-Guldberg et al., 2018]] ; [[#Sainz--2019|Sainz et al., 2019]] ; [[#Lebel--2020|Lebel et al., 2020]] ). Salinity intrusions into freshwater aquaculture systems have changed oxygen and water quality of inland ponds, resulting in mortalities in areas such as India and Bangladesh ( ''medium confidence'' ) ( [[#Dubey--2017|Dubey et al., 2017]] ; [[#Dabbadie--2018|Dabbadie et al., 2018]] ). Rapid changes in temperature, precipitation, droughts, floods and erosion have created significant production losses for aquatic farmers in Cambodia, Laos, Myanmar, Thailand, Viet Nam and Ghana ( ''medium confidence'' ) ( [[#Asiedu--2017|Asiedu et al., 2017]] ; [[#Pongthanapanic--2019|Pongthanapanic et al., 2019]] ; [[#Lebel--2020|Lebel et al., 2020]] ). Algal blooming and inland lake browning related to warming was found to negatively affect fish biomass ( [[#van%20Dorst--2018|van Dorst et al., 2018]] ). Observed indirect effects of climate change on aquaculture include extreme weather events that damage coastal aquaculture infrastructure or enable flooding, both leading to animal escapees (e.g., fish, shrimp), damaged livelihoods and interactions with wild species ( ''high agreement'' , ''medium evidence'' ) ( [[#Beveridge--2018b|Beveridge et al., 2018b]] ; [[#Dabbadie--2018|Dabbadie et al., 2018]] ; [[#Kais--2018|Kais and Islam, 2018]] ; [[#Pongthanapanic--2019|Pongthanapanic et al., 2019]] ; [[#Ju--2020|Ju et al., 2020]] ).

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