Embryos of an Antarctic zooplankton require anoxia for dormancy, are permeable to lipophilic chemicals, and reside in sediments containing PCBs

Abstract

Zooplankton in Antarctic maritime lakes face challenges imposed by anthropogenic chemicals. Studies on temperate species suggest that lipophilic chemicals will accumulate in dormant embryos of Antarctic zooplankton and decrease hatching success, thereby threatening centuries of accumulated genetic diversity that would increase population resilience in the face of climate change. We evaluated the potential for lakes to act as sinks for legacy pollutants in the maritime Antarctic by testing sediments for polychlorinated biphenyls (PCBs) previously identified in soil, flora and fauna of lake catchments. Direct tests of embryo permeability to chemicals are confounded by potential adhesion of chemicals to the embryo surface and limited biomass available. Therefore, in order to assess the potential for lipophilic chemicals to penetrate and passively accumulate in dormant embryos of Antarctic lacustrine zooplankton, we evaluated the effect of anoxia on post-diapause development in the calanoid copepod, Boeckella poppei, and then used chemical anoxia induced by rotenone as a reporter for permeability of these embryos to moderately lipophilic chemicals. The data presented demonstrate that embryos of B. poppei from Antarctic lake sediments will passively accumulate moderately lipophilic chemicals while lying dormant in anoxic sediments. Implications for legacy POPs in sediments of Antarctic maritime lakes are discussed.

Loss of a freshwater copepod species from El Junco Lake, Galápagos following the introduction and eradication of the Nile tilapia

“…Similarly, rotenone may reduce or inhibit the success of hatching of the resting-eggs from the sediments in calanoid copepod species whose embryos are permeable to it (Covi et al, 2016;Reed et al, 2018).…”

Reversible intracellular acidification and depletion of NTPs provide a potential physiological origin for centuries of dormancy in an Antarctic freshwater copepod

“…Boeckella poppei (Marzek, 1901), is an important and broadly distributed freshwater copepod found in South America, the subantarctic, and Antarctica 24 . Recent research on B. poppei demonstrates that this species shares physiological, developmental, and structural characteristics with A. franciscana 25 , 26 . In both species, light and oxygen are required to break out of the endogenously programmed form of dormancy (diapause) 25 , 27 .…”

Population features of Boeckella poppei in Lake Wujka, King George Island

“…A limited number of recent studies have focused on the ultrastructure, ecological characteristics, dispersal, and origin of B. poppei in widely separated maritime and continental Antarctic locations (Reed et al, 2021;Bayly et al, 2003;Butler et al, 2005;Gibson & Zale, 2006;Janiec, 1988;1996). Heywood (1970) and Weller (1977) reported the age and sex structure of Boeckella silvestri (Daday, 1901) and B. poppei populations at Signy Island, South Orkney Island.…”

“…Heywood (1970) and Weller (1977) reported the age and sex structure of Boeckella silvestri (Daday, 1901) and B. poppei populations at Signy Island, South Orkney Island. The embryos of B. poppei from sediments of the lake on Barton Peninsula, King George Island, Antarctica, will passively accumulate moderately lipophilic chemicals while lying dormant in anoxic sediments, which can decrease hatchings uccess (Reed et al, 2018). The current known distribution of B. po ppei extends beyond the Antarctic to include Argentina and Chile.…”

“…King George Island is the largest one of the South Shetland Islands, with an area of 1.312 km 2 , about V. Trokhymets, V. Gorobchyshyn, I. Kozeretska: Population features of Boeckella poppei 90% of which is under permanent ice cover (Rakusa-Suszczewski, 2002). There are several permanent freshwater bodies on the island, with Lake Wujka near the Polish Arctowski Station being one of the largest (Figure).…”