The effect of desiccation on the emission of volatile bromocarbons from two common temperate macroalgae

Abstract

Abstract. Exposure of intertidal macroalgae during low tide has been linked to the emission of a variety of atmospherically-important trace gases into the coastal atmosphere. In recent years, several studies have investigated the role of inorganic iodine and organoiodides as antioxidants and their emission during exposure to combat oxidative stress, yet the role of organic bromine species during desiccation is less well understood. In this study the emission of dibromomethane (CH 2 Br 2 ) and bromoform (CHBr 3 ) during exposure and desiccation of two common temperate macroalgae, Fucus vesiculosus and Ulva intestinalis, is reported. Determination of the impact exposure may have on algal physiological processes is difficult as intertidal species are adapted to desiccation and may undergo varying degrees of desiccation before their physiology is affected. For this reason we include comparisons between photosynthetic capacity (F v /F m ) and halocarbon emissions during a desiccation time series. In addition, the role of rewetting with freshwater to simulate exposure to rain was also investigated. Our results show that an immediate flux of bromocarbons occurs upon exposure, followed by a decline in bromocarbon emissions. We suggest that this immediate bromocarbon pulse may be linked to volatilisation or emissions of existing bromocarbon stores from the algal surface rather than the production of bromocarbons as an antioxidant response.

Halocarbon emissions by selected tropical seaweeds: species-specific and compound-specific responses under changing pH

“…The state of health of the seaweeds was assessed prior to the experiment using a diving Pulse Amplitude Modulator (PAM) Fluorometer (Zarges 40701 Heinz Walz GMBH) and after the 4 h incubation ( Chaloub et al, 2010 ; Leedham Elvidge et al, 2015 ; Li et al, 2014 ). The change in F v ∕ F m was calculated according to the following formula:…”

“…A previous study on the red seaweed, Eucheuma denticulatum , found a varying response to pH: CH 2 I 2 emitted correlates positively with increasing pH (8.2–8.8 using an acid–base titration method) whilst the opposite was observed for CHBr 3 and CHBr 2 Cl under the same changes ( Mtolera et al, 1996 ). Halocarbon emission by algae is also affected by irradiance ( Nightingale, Malin & Liss, 1995 ; Mtolera et al, 1996 ; Laturnus et al, 2000 ; Keng et al, 2013 ); desiccation ( Nightingale, Malin & Liss, 1995 ; Leedham Elvidge et al, 2015 ); oxidative stress ( Abrahamsson et al, 2003 ); tissue age ( Nightingale, Malin & Liss, 1995 ); tissue wounding/grazing ( Nightingale, Malin & Liss, 1995 ; Sundström et al, 1996 ) and photosynthetic activity ( Sundström et al, 1996 ; Goodwin, North & Lidstrom, 1997 ). The way irradiance affects the emission of halocarbons by seaweeds could be caused by changes in photosynthetic activity ( Goodwin, North & Lidstrom, 1997 ; Ekdahl, Pedersén & Abrahamsson, 1998 ; Laturnus et al, 2000 ).…”

The emission of volatile halocarbons by seaweeds and their response towards environmental changes

“…Seaweeds are known to be emitters of the short-lived brominated compounds including CHBr3 and CH2Br2 and could contribute to significantly higher concentrations (up to three-fold) of CHBr3, CHBr2Cl, CH2Br2, CHIBr2, CH2IBr and CH2I2 in coastal areas compared to areas further offshore (Yamamoto et al 2001;Gibble, 2003;Keng et al 2013;Leedham et al 2013;Leedham Elvidge et al 2015). The significant role of seaweeds in the production of bromoform, which is often the most abundant biogenic brominated halocarbon released by seaweeds, was first reported by Carpenter and Liss (2000): that seaweeds account to 70% of global bromoform production.…”

“…The combined effect, be it temporary or long-termed, of these interactions results in variations in physiology, growth, morphology and survival of the species (Harley et al 2012). In the attempt to provide a comprehensive prediction of the global halocarbon budget, considerable efforts have been made to establish and to narrow down the environmental factors responsible for the enhanced emission of halocarbons by the seaweeds (Nightingale et al 1995;Mtolera et al 1996;Manley and Barbero, 2001;Abrahamsson et al 2003;Carpenter et al 2000;Bravo-Linares et al 2010;Laturnus et al 2010;Keng et al 2013;Leedham Elvidge et al 2015, Mithoo-Singh et al 2017. Some of these studies were carried out in a controlled environment while others were conducted in situ.…”

Effect of irradiance on the emission of short-lived halocarbons from three common tropical marine microalgae

“…Of the biogenic sources of VSLHs, marine algae have been the most extensively studied. Previous laboratory and in-situ studies have shown prominent contribution of VSLHs from macro- (seaweeds) and microalgae (phytoplankton) of temperate, polar and tropical regions (Lovelock, Maggs & Wade, 1973; Sturges, Cota & Buckley, 1992; Laturnus, Wiencke & Klöser, 1995; Carpenter & Liss, 2000; Abrahamsson et al, 2004; Keng et al, 2013; Leedham et al, 2013; Leedham Elvidge et al, 2015; Hughes & Sun, 2016; Mithoo-Singh et al, 2017; Lim et al, 2017; Lim et al, 2018; Li et al, 2018). In recent times, more attention has been paid to the biogenic emission from tropical regions due to the prevalence of deep convection due to a combination of high humidity and high insolation (Bergman et al, 2012).…”