The effects of in-vitro pH decrease on the gametogenesis of the red tree coral, Primnoa pacifica

Abstract

Primnoa pacifica is the most ecologically important coral species in the North Pacific Ocean and provides important habitat for commercially important fish and invertebrates. Ocean acidification (OA) is more rapidly increasing in high-latitude seas because anthropogenic CO 2 uptake is greater in these regions. This is due to the solubility of CO 2 in cold water and the reduced buffering capacity and low alkalinity of colder waters. Primnoa pacifica colonies were cultured for six to nine months in either pH 7.55 (predicted Year 2100 pH levels) or pH 7.75 (Control). Oocyte development and fecundity in females, and spermatocyst stages in males were measured to assess the effects of pH on gametogenesis. Oocyte diameters were 13.6% smaller and fecundities were 30.9% lower in the Year 2100 samples. A higher proportion of vitellogenic oocytes (65%) were also reabsorbed (oosorption) in the Year 2100 treatment. Lower pH appeared to advance the process of spermatogenesis with a higher percentage of later stage sperm compared to Control. There was a laboratory effect observed in all measurement types, however this only significantly affected the analyses of spermatogenesis. Based on the negative effect of acidification on oogenesis and increased rate of oosorption, successful spawning could be unlikely in an acidified ocean. If female gametes were spawned, they are likely to be insufficiently equipped to develop normally, based on the decreased overall size and therefore subsequent limited amount of lipids necessary for successful larval development.

Invariant Gametogenic Response of Dominant Infaunal Bivalves From the Arctic Under Ambient and Near-Future Climate Change Conditions

“…Increasing temperature and carbon dioxide concentrations affect species physiology through increased metabolism (Parker et al, 2013;Jager et al, 2016;Leung et al, 2020), and sometimes the suppression of feeding (Stumpp et al, 2012;Kurihara et al, 2013;Appelhans et al, 2014), which directly affects per offspring investment (Moran and McAlister, 2009;Pettersen et al, 2019), and gamete behavior post spawning (Verkaik et al, 2016). Energy stored as gametes can also be reabsorbed and act as a trade-off with fecundity (Stumpp et al, 2012;Verkaik et al, 2017;Rossin et al, 2019). However, considerable physiological resilience to ocean acidification has been demonstrated at various life-cycle stages in bivalves (Dell'Acqua et al, 2019), echinoderms (Verkaik et al, 2017), and corals (Gizzi et al, 2017), and during short incubations, appears to show no significant effects on growth and reproduction in benthic invertebrates (Dell'Acqua et al, 2019), even in food limited scenarios (Goethel et al, 2017).…”

Phenotypic Plasticity or a Reproductive Dead End? Primnoa pacifica (Cnidaria: Alcyonacea) in the Southeastern Alaska Region

“…Three to five polyps from each sample were then taken and decalcified in Rapid Bone Decalcifier (Electron Microscopy Sciences), serially dehydrated in a graded ethanol series, cleared with toluene and then infiltrated in paraffin wax for 48 h at 56 • C. Wax blocks were then serially sectioned at 5 microns on a Leica RM2235 rotary microtome, leaving 90 microns between slides. This distance has been determined to be the nuclear diameter (Waller et al, 2014;Rossin et al, 2019), and thus provides adequate distance between sections allowing for accurate imaging of all oocytes within a polyp and prevents double counting when calculating fecundities.…”

“…Primnoa pacifica is one of the more well-known and studied cold-water corals in the world. Growth rates (Andrews et al, 2002;Aranha et al, 2014), reproduction (Waller et al, 2014), effects of ocean acidification (Rossin et al, 2019), distribution, ecology, and taxonomy have all been investigated (Krieger, 2001;Krieger and Wing, 2002;Cairns and Bayer, 2005;DuPreez and Tunnicliffe, 2011;Stone et al, 2014;Stone and Mondragon, 2018). Primnoa pacifica is one of only a few species world-wide known to display deep-sea emergence, a phenomenon where animal populations primarily found in deep water are able to thrive in much shallower water, likely due to unique conditions in these rare locations (Stone and Mondragon, 2018).…”

“…These thickets form important habitat for the myriad of associated species including many of commercial importance (Krieger and Wing, 2002;DuPreez and Tunnicliffe, 2011;Stone et al, 2014). Their characteristics of large size, arborescent morphology, and slow growth make them particularly vulnerable to anthropogenic impacts, including interactions with fishing gear (Krieger, 2001;Stone et al, 2014) but also global climate change (Stone and Mondragon, 2018;Rossin et al, 2019). In June 2006 five small areas (46 km 2 in total) in the Gulf of Alaska were designated as Habitat Areas of Particular Concern, prohibiting the use of bottom contact gear to protect these important cold-water coral ecosystems (Stone et al, 2014).…”

Understanding growth and age of red tree corals (Primnoa pacifica) in the North Pacific Ocean

“…The gorgonian Primnoa pacifica [ 20 ], also known as the red tree coral, are ecologically important deep-sea corals in the North Pacific Ocean [ 4 ]. They have been referred to as “keystone species,” “foundation species,” and “ecosystem engineers” [ 4 , 21 ]. These animals are comprised of an internal skeleton arising from the holdfast attached directly to hard substrate.…”