Extensive dissolution of live pteropods in the Southern Ocean

Abstract

time it grows to 1 cm in shell diameter 21 . Analysis was carried out on both freshly 90 caught material preserved directly upon collection and on specimens that were 91 incubated under manipulated CO 2 levels (375 to 750 parts per million at 4°C) in order 92 to establish a response index. All freshly-caught and incubated specimens were 93 preserved in 70% ethanol. Subsequently, they were treated to dehydrate shell-layers 94 and to remove the periostracum (Fig. 3) so that the state of the underlying shell matrix 95 could be examined using SEM. 96 97 Different degrees of dissolution were identified in incubated shells of live pteropods 98 (see supplementary information). We categorised them into three main levels 99 according to the degree of encroachment upon the upper prismatic layer and into the 100 upper shell layer (Fig. 4). Specimens were scored blind and then correlated back to 101 5 the experimental conditions. Incubations in which even only a slight degree of 102 undersaturation was experienced for 8 d (Ω A 0.94-1.12, pCO 2 of 675 µatm) was 103 sufficient to cause substantial dissolution of the shell matrix relative to the 104 supersaturated control (Ω A 1.62-1.78, Fig. 5). We then examined freshly caught 105 material, preserved directly upon collection, for signs of such shell dissolution. 106 107 L. helicina antarctica juveniles were found at all sampling stations, with northern 108 stations (<57ºS) containing higher abundances (7.2 x 10 4 to 3.4 x 10 4 ind. m -2 ) than 109 those to the south (>57ºS; 2.9 x 10 2 to 1.9 x 10 3 ind. m -2 ). At station Su9, we found L.

The effect of elevated carbon dioxide on the sinking and swimming of the shelled pteropod Limacina retroversa

“…saturation state have also shown signs of dissolution under scanning electron microscopy 56 (Bednaršek, et al 2012, Bednaršek, et al 2014, Bednaršek, and Ohman. 2015.…”

Limacina helicinashell dissolution as an indicator of declining habitat suitability owing to ocean acidification in the California Current Ecosystem

“…Their spatial habitat stretches along the CCE and their vertical habitat encompasses the upper 75-150 m during day and night, with some healthy individuals capable of vertically migrating much deeper [28,29]. The CCE is a major upwelling region that is already experiencing 'acidified' conditions [11][12][13][14] under which thin pteropod shells are vulnerable to dissolution [30][31][32], even by short-term exposures (4-14 days) to near-saturated waters (V ar 1), which makes them a suitable indicator for monitoring small-scale changes in the carbonate chemistry environment [30]. The existence of strong vertical gradients in aragonite saturation in the first 100 m of the CCE further accelerated by anthropogenic OA, where undersaturation protrudes into the pteropod vertical habitat provided a setting for estimating quantitative relationships between in situ undersaturation and shell dissolution.…”

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

“…While the Southern Ocean presently accounts for 75% of the global excess heat uptake and 43% of the anthropogenic carbon dioxide uptake (Frölicher et al, 2014), it is uncertain how climate change will impact the processes governing these uptake rates in the future . In addition, surface waters are experiencing declines in pH and altered aragonite saturation states (ocean acidification), which are already impacting some marine organisms (Bednaršek et al, 2012). However, the degree to which ocean acidification will impact food webs and trophic interactions remains unclear.…”