Biology subjects

Goetze, E.

Publications and source records attributed to Goetze, E..

3 recordsLinked to original sources

bioRxiv2020

Current and future ocean chemistry negatively impacts calcification in predatory planktonic snails

Planktonic gastropods mediate an important flux of carbonate from the surface to the deep ocean. However, we know little about the response of atlantid heteropods, the only predatory, aragonite shelled zooplankton, to ocean acidification (OA), and they are not incorporated in any carbonate flux models. Here we quantify the effects of OA on calcification and gene expression in atlantids across three pH scenarios: mid-1960s, ambient, and future 2050 conditions. Atlantid calcification responses to decreasing pH were negative, but not uniform, across the three scenarios. Calcification was reduced from mid-1960s to ambient conditions, and longer shells were grown under 2050 conditions. Differential gene expression indicated a stress response at both ambient and future conditions, with down-regulation of growth and biomineralization genes with decreasing pH. Our results suggest that ocean chemistry in the South Atlantic is already limiting atlantid calcification, and that exposure to near-future OA triggers rapid shell growth under stress.

ecology↗

bioRxiv2020

From sea surface to seafloor: a benthic allochthonous eDNA survey for the abyssal ocean

Diverse and remote deep-sea communities are critically under-sampled and increasingly threatened by anthropogenic impacts. Environmental DNA (eDNA) metabarcoding could facilitate rapid and comprehensive biotic surveys in the deep ocean, yet many aspects of the sources and distribution of eDNA in the deep sea are still poorly understood. In order to examine the influence of the water column on benthic eDNA surveys in regions targeted for deep-sea polymetallic nodule mining, we investigated the occurrence of pelagic eDNA across: (1) two different deep-sea habitat types, abyssal plains and seamounts, (2) benthic sample types, including nodules, sediment, and seawater within the benthic boundary layer (BBL), and (3) sediment depth horizons (0-2 cm, 3-5 cm). Little difference was observed between seamounts and the adjacent abyssal plains in the proportion of legacy pelagic eDNA sampled in the benthos, despite an > 1000 m depth difference for these habitats. In terms of both reads and amplicon sequence variants (ASVs), pelagic eDNA was minimal within sediment and nodule samples (< 2%), and is unlikely to affect benthic surveys that monitor resident organisms at the deep seafloor. However, pelagic eDNA was substantial within the BBL (up to 13 % ASVs, 86% reads), deriving both from the high biomass upper ocean as well as deep pelagic residents. While most pelagic eDNA found in sediments and on nodules could be sourced from the epipelagic for metazoans, protist legacy eDNA sampled on these substrates appeared to originate across a range of depths in the water column. Some evidence of eDNA degradation across a vertical sediment profile was observed for protists, with higher diversity in the 0-2 cm layer and a significantly lower proportion of legacy pelagic eDNA in deeper sediments (3-5 cm). Study-wide, our estimated metazoan sampling coverage ranged from 40% to 74%, despite relatively large sample size. Future deep-sea eDNA surveys should examine oceanographic influences on eDNA transport and residence times, consider habitat heterogeneity at a range of spatial scales in the abyss, and aim to process large amounts of material per sample (with replication) in order to increase the sampling coverage in these diverse deep ocean communities.

ecology↗

bioRxiv2019

The origin and diversification of pteropods predate past perturbations in the Earth’s carbon cycle

Pteropods are a group of planktonic gastropods that are widely regarded as biological indicators for assessing the impacts of ocean acidification (OA). Their thin aragonitic shells are highly sensitive to acute changes in ocean chemistry. However, to gain insight into their potential to adapt to current climate change, we need to accurately reconstruct their evolutionary history and assess their responses to past changes in Earths carbon cycle. Here, we resolve the phylogeny and timing of pteropod evolution with a phylogenomic dataset incorporating 21 new species and new fossil evidence. In agreement with traditional taxonomy, we recovered the first molecular support for a division between sea butterflies (Thecosomata: mucus-web feeders) and sea angels (Gymnosomata: active predators). Molecular dating demonstrated that these two lineages diverged in the early Cretaceous, and that all main pteropod clades, including shelled, partially-shelled and unshelled groups, diverged in the mid to late Cretaceous. Hence, these clades originated prior to and subsequently survived major global change events, including the Paleocene Eocene Thermal Maximum (PETM), which is the closest analogue to modern-day ocean acidification and warming. Our findings indicate that aragonitic calcifiers have been resilient to extreme perturbations in the Earths carbon cycle over evolutionary timescales.

evolutionary biology↗