Diversity and Distribution of Deep-Sea Shrimps in the Ross Sea Region of Antarctica

Abstract

<div><p>Although decapod crustaceans are widespread in the oceans, only Natantia (shrimps) are common in the Antarctic. Because remoteness, depth and ice cover restrict sampling in the South Ocean, species distribution modelling is a useful tool for evaluating distributions. We used physical specimen and towed camera data to describe the diversity and distribution of shrimps in the Ross Sea region of Antarctica. Eight shrimp species were recorded: <i>Chorismus antarcticus; Notocrangon antarcticus; Nematocarcinus lanceopes; Dendrobranchiata</i>; <i>Pasiphaea scotiae</i>; <i>Pasiphaea</i> cf. <i>ledoyeri</i>; <i>Petalidium</i> sp., and a new species of <i>Lebbeus</i>. For the two most common species, <i>N. antarcticus</i> and <i>N. lanceopes</i>, we used maximum entropy modelling, based on records of 60 specimens and over 1130 observations across 23 sites in depths from 269 m to 3433 m, to predict distributions in relation to environmental variables. Two independent sets of environmental data layers at 0.05° and 0.5° resolution respectively, showed how spatial resolution affected the model. <i>Chorismus antarcticus</i> and <i>N. antarcticus</i> were found only on the continental shelf and upper slopes, while <i>N. lanceopes, Lebbeus</i> n. sp., <i>Dendrobranchiata, Petalidium</i> sp., <i>Pasiphaea</i> cf. <i>ledoyeri,</i> and <i>Pasiphaea scotiae</i> were found on the slopes, seamounts and abyssal plain. The environmental variables that contributed most to models for <i>N. antarcticus</i> were depth, chlorophyll-<i>a</i> concentration, temperature, and salinity, and for <i>N. lanceopes</i> were depth, ice concentration, seabed slope/rugosity, and temperature. The relative ranking, but not the composition of these variables changed in models using different spatial resolutions, and the predicted extent of suitable habitat was smaller in models using the finer-scale environmental layers. Our modelling indicated that shrimps were widespread throughout the Ross Sea region and were thus likely to play important functional role in the ecosystem, and that the spatial resolution of data needs to be considered both in the use of species distribution models.</p></div