Desalination plants as plankton sampling devices in temporal studies: proof‐of‐concept and suggestions for the future

Abstract

Long-term records of zooplankton distribution and abundance are increasingly being used as indicators of climate change. The North Atlantic, because of the 80 years of Continuous Plankton Recorder (CPR) surveys, is well-represented with such time series. However, there are few long-term data sets from the Pacific Ocean and especially from Antarctica, where traditional plankton sampling is logistically challenging. Here we test an alternative sampling method, the primary filter (PF) of the Scott Base reverse-osmosis (RO) desalination plant, which had the same mesh size (100 µm) as our standard plankton tows. We show, by qualitative comparison to fresh plankton samples collected with a plankton net, that the PF collects a representative zooplankton community, does not damage delicate or fragile forms (e.g., appendicularians, ctenophores, medusae, chaetognaths, pteropods, polychaetes, embryos with intact fertilization membranes, pilidia, bipinnaria), and that the large volumes of seawater filtered allow collection of rare meroplankton members. We further show that seasonal changes can be detected in the zooplankton when PF samples are fixed in formalin for later analysis. Desalination plant PFs may provide an innovative solution to study temporal patterns in the Antarctic zooplankton and have the potential to provide long-term data sets from other poorly sampled regions.

The meroplankton community of the oceanic Ross Sea during late summer

“…A dominance of polychaetes in terms of abundance has also been noted in previous Antarctic sampling in both coastal (Stanwell-Smith et al 1999, Freire et al 2006, Sewell 2006, Heimeier et al 2010, Sewell & Jury 2011) and oceanic studies (Shreeve & Peck 1995, Scheltema et al 1997, Vázquez et al 2007). Caution is needed when comparing previously published work with the present study, as there is great potential for the early stages of Pelagobia longicirrata , a highly abundant pelagic polychaete, to be mistaken for the nectochaete stage from a benthic species (Freire et al 2006, Sewell & Jury 2009). Bhaud et al (1999) described 18 types of polychaete larvae from Antarctica with particularly high biodiversity among the family Spionidae, which is also the most diverse group found in our samples, comprising five mOTUs.…”

“…Further, there is now considerable evidence that larvae are abundant in Antarctic coastal environments, both on the Antarctic Peninsula and in the Ross Sea (Stanwell-Smith et al 1999, Absher et al 2003, Freire et al 2006, Sewell 2006, Thornhill et al 2008, Bowden et al 2009, Sewell & Jury 2009, 2011.…”

“…Despite the number of Antarctic species with a planktonic life stage being smaller than in other environments (Poulin et al 2002), it is noticeable that the most conspicuous and abundant taxa in many Antarctic benthic assemblages, such as the sea urchin Sterechinus neumayeri (Meissner), the starfish Odontaster validus (Koehler), the ophiuroid Ophionotus victoriae Bell and the scallop Adamussium colbecki (Smith), have a planktonic dispersal stage (Poulin et al 2002 and references therein). Further, there is now considerable evidence that larvae are abundant in Antarctic coastal environments, both on the Antarctic Peninsula and in the Ross Sea (Stanwell-Smith et al 1999, Absher et al 2003, Freire et al 2006, Sewell 2006, Thornhill et al 2008, Bowden et al 2009, Sewell & Jury 2009, 2011).…”

Using DNA barcoding and phylogenetics to identify Antarctic invertebrate larvae: Lessons from a large scale study

“…At all sites, meroplankton samples were collected with a 100 μm mesh collapsible plankton net from a single hole drilled through the annual sea ice; as described in detail in (Sewell, 2005). In 2002, we also obtained larvae from the filter bag on the seawater intake of the Scott Base reverse osmosis plant as described in Sewell and Jury (Sewell and Jury, 2009).…”