Early life stages in the life cycle of Antarctic silverfish, Pleuragramma antarcticum in Terra Nova Bay, Ross Sea

Abstract

Abstract:The nototheniid Pleuragramma antarcticum (Boulenger, 1902), is the dominant pelagic fish in waters of the continental shelf in High Antarctic regions. Larvae and juveniles of this species comprise the majority of ichthyoplankton at many locations around Antarctica including the Weddell Sea and the western Ross Sea, where it may amount to 98% of the ichthyoplankton. Its life cycle has been the subject of a number of studies but spawning and embryological development are still uncertain. Eggs with embryos and newly hatched larvae of P. antarcticum were collected in November 2002 near the Italian Antarctic station at Terra Nova Bay through holes drilled in the sea ice. Eggs and yolk-sac larvae were floating among the platelet ice below the solid cap of congelation ice. Eggs were 2.2-2.5 mm in diameter and contained embryos at an advanced stage of development. Hatching occurred from mid-November onwards, and newly hatched larvae averaged 9.3 mm SL. This paper provides the detailed description of embryos and newly hatched larvae in terms of pigmentation pattern and morphometric characteristics, thus allowing a significant advance in our understanding of the early life history of P. antarcticum in the Ross Sea, and extending the knowledge of the life cycle of this key Antarctic species.

Freezing resistance of antifreeze-deficient larval Antarctic fish

“…antarcticum also hatches into these icy waters with drastically inadequate amounts of AFPs for protection against freezing, despite the fact that their positively buoyant egg places them in contact with the surface ice upon hatching (Vacchi et al, 2003), and older larval stages are most abundant in the iciest top 50·m of the water column (Granata et al, 2002;Guglielmo et al, 1998;Hubold, 1984). A comparison of hatchling larval homogenates and yolk TH values between G. acuticeps and P. antarcticum shows that the latter (from which individual fluids could not be obtained) likely have serum and intestinal fluids with as little as 25% of the TH observed in the already AFP-deficient G. acuticeps fluids at the time of hatching (Table·1).…”

“…Eggs and newly hatched larvae of Pleuragramma antarcticum Boulenger 1902 were obtained in mid-November Paul A. Cziko and others (Vacchi et al, 2003). Large numbers of eggs and larvae were found encased within and floating among platelet ice dislodged from the underside of the sea ice while drilling fishing holes over 25-452·m of water near 74°41ЈS, 164°05ЈE.…”

Distributions of krill and Antarctic silverfish and correlations with environmental variables in the western Ross Sea, Antarctica

“…Antarctic silverfish tend to spawn in ice-covered coastal regions, ice shelf areas, and polynyas (Vacchi et al 2004(Vacchi et al , 2012a, and use sea ice as a nursery for their eggs and early life stages (Kellermann 1986a,b, Daneri & Carlini 2002. Antarctic silverfish spawn in the lower water column, and embryos, which are slightly positively buoyant, are found associated with sea-ice thickness and platelet ice (Vacchi et al 2004(Vacchi et al , 2012a. The slow surface speeds that emerged as a characteristic for the Antarctic silverfish habitat will facilitate retention of the early life stages in the productive polynya region.…”

Impact of Climate Change on Fishes in Complex Antarctic Ecosystems

“…In the southern Weddell Sea, P. antarcticum accounts for most of the overall fish production, and stock density was estimated to amount at least 1 ton km À 2 (Hubold, 1992). Though usually found in the free water column, its life cycle strategy, including its feeding dynamics, seems to be closely associated with the sea ice (Daniels, 1982;La Mesa and Eastman, 2012;Vacchi et al, 2004). Besides adult P. antarcticum, larvae and early juveniles of several notothenioid species dominate the neritic pelagic fish community numerically.…”

“…Barrera-Oro and Lagger, 2010;Detrich et al, 2005;Kock et al, 2006;Moreno, 1980). Others species, for example, P. antarcticum, have pelagic eggs (Faleyeva and Gerasimchuk, 1990;Vacchi et al, 2004). The eggs are usually large 369 Impact of Climate Change on Fishes in Complex Antarctic Ecosystems and yolky, so relative fecundity is low in most species, particularly in high Antarctic notothenioids (Hubold, 1992;Kock, 1992;Kock and Kellermann, 1991).…”