Maria Chiara Alvaro

Skin-digging tanaids: the unusual parasitic behaviour of Exspina typica in Antarctic waters and worldwide deep basins

Abstract The order Tanaidacea includes over 1000 species which are mainly free-living or tube-dwelling detritivores. Exspina typica Lang, 1968 represents an exception to these common life styles, having being found in the intestine and body cavity of deep sea holothuroids. The 2008 New Zealand ‘IPY-CAML Cruise’ held in the Ross Sea collected several deepwater holothuroids that were observed to carry specimens of E. typica inside their coelomic cavity. A clear interpretation of this association was hence possible. Even if E. typica shows slight adaptations to a parasitic life style, the tanaids were found to actively ‘dig’ into the hosts skin, grasping tissue with their claws and producing tunnels in the body wall. It is therefore possible to clearly define this association, which is here reported from the Antarctic for the first time, as parasitism.

Ross Sea Mollusca from the Latitudinal Gradient Program: R/V Italica 2004 Rauschert dredge samples

Abstract Information regarding the molluscs in this dataset is based on the Rauschert dredge samples collected during the Latitudinal Gradient Program (LGP) on board the R/V “Italica” in the Ross Sea (Antarctica) in the austral summer 2004. A total of 18 epibenthic dredge deployments/samplings have been performed at four different locations at depths ranging from 84 to 515m by using a Rauschert dredge with a mesh size of 500μm. In total 8,359 specimens have been collected belonging to a total of 161 species. Considering this dataset in terms of occurrences, it corresponds to 505 discrete distributional records (incidence data). Of these, in order of abundance, 5,965 specimens were Gastropoda (accounting for 113 species), 1,323 were Bivalvia (accounting for 36 species), 949 were Aplacophora (accounting for 7 species), 74 specimens were Scaphopoda (3 species), 38 were Monoplacophora (1 species) and, finally, 10 specimens were Polyplacophora (1 species). This data set represents the first large-scale survey of benthic micro-molluscs for the area and provides important information about the distribution of several species, which have been seldom or never recorded before in the Ross Sea. All vouchers are permanently stored at the Italian National Antarctic Museum (MNA), Section of Genoa, enabling future comparison and crosschecking. This material is also currently under study, from a molecular point of view, by the barcoding project “BAMBi” (PNRA 2010/A1.10).

‘Hitchhiker’ polynoid polychaetes in cold deep waters and their potential influence on benthic soft bottom food webs

Abstract We describe a new association for Antarctica, involving an holothuroid host, Bathyplotes bongraini Vaney, 1914, and a parasitic polynoid polychaete, Eunoe opalina McIntosh, 1885, which lives on the host body. Both species have never been recorded in the study area, the Ross Sea. The ecological definition of this partnership is difficult to assess, being a mix of phoresis, protective association, parasitism and, possibly, kleptocommensalism. Eunoe opalina emerges also as a true predator, ingesting several food items that do not belong to the diet of Bathyplotes. We compare this association with analogous examples known from shallow tropical environments as well as bathyal and abyssal depths. Given the conspicuous similarities between the deep water and high latitude examples of this kind of association, a possible common origin is hypothesized. Although the role of such a kind of parasitic relationships in Antarctic communities remains to be fully evaluated, it seems evident that, at high latitudes, where trophic levels are simplified and food webs do not have much redundancy, the impact of such a ‘multitasking’ predator-parasite as E. opalina might be of a greater magnitude than its shallow water tropical counterpart.

Distributional records of Ross Sea (Antarctica) Tanaidacea from museum samples stored in the collections of the Italian National Antarctic Museum (MNA) and the New Zealand National Institute of Water and Atmospheric Research (NIWA)

Abstract Here we present distributional records for Tanaidacea specimens collected during several Antarctic expeditions to the Ross Sea: the Italian PNRA expeditions (“V”, 1989/1990; “XI”, 1995/1996; “XIV”, 1998/1999; “XIX”, 2003/2004; “XXV”, 2009/2010) and the New Zealand historical (New Zealand Oceanographic Institute, NZOI, 1958-1961) and recent (“TAN0402 BIOROSS” voyage, 2004 and “TAN0802 IPY-CAML Oceans Survey 20/20” voyage, 2008) expeditions. Tanaidaceans were obtained from bottom samples collected at depths ranging from 16 to 3543 m by using a variety of sampling gears. On the whole, this contribution reports distributional data for a total of 2953 individuals belonging to 33 genera and 50 species. All vouchers are permanently stored in the Italian National Antarctic Museum collection (MNA), Section of Genoa (Italy) and at the National Institute of Water and Atmospheric Research (NIWA Invertebrate Collection), Wellington (New Zealand).

Polynoid polychaetes living in the gut of irregular sea urchins: a first case of inquilinism in the Southern Ocean

Abstract Many different polychaete-echinoderm relationships have been described, from tropical to polar environments. Most of these associations have been generally defined as ‘commensal’, with polychaetes guests usually found on the oral surface of their hosts or, in a very few cases, even inside the hosts body. Here we present an inquilinistic association involving two Antarctic species, the polychaete Gorekia crassicirris (Willey, 1902) (Polynoidae) and the irregular sea urchin Abatus nimrodi (Koheler, 1911) (Schizasteridae) found in the Ross Sea. This record is only the second worldwide for this kind of association, after that of the polychaete Benthoscolex cubanus which lives in the gut of the spatangoid Archeopneustes hystrix in Caribbean waters. Gorekia crassicirris seems to be a polyxenous species as it was also observed on another schizasterid, Brachysternaster chescheri Larrain, 1985 in the Weddell Sea. Considering that A. nimrodi is absent from that area and that the two sea urchin species have a disjoint distribution, it is possible that a ‘host-switch’ phenomenon occurred at some stage. We review the available literature to compare the Antarctic pairing with the other known examples of similar associations.

Host-shift speciation in Antarctic symbiotic invertebrates: further evidence from the new amphipod species Lepidepecreella debroyeri from the Ross Sea?

Lepidepecreella debroyeri n. sp. (Amphipoda, Lysianassoidea) is described from specimens collected at Terra Nova Bay (Ross Sea, Antarctica) in the framework of several scientific expeditions of the Italian National Antarctic Research Program. This amphipod is an obligate parasite of the regular sea urchin Sterechinus neumayeri (Meissner, 1900) and also occurs at diving depths. L. debroyeri n. sp. shares with Lepidepecreella andeep Berge, Vader & Lockhart, 2004, an abyssal species described for the Weddell Sea, an almost identical morphology and ecological traits, being both associated with sea urchins of two different families. This close relationship could be the result of a host-shift phenomenon that occurred during the high number of glacial cycles, possibly rendering the preferred host unavailable. L.debroyeri n. sp. shows a high degree of variation in terms of sex ratio and population structure between different host specimens, a fact that could be related to a great mobility of this small parasitic amphipod. The new amphipod species is itself the subject of a hyperparasitic interaction, carrying tantulocarid crustaceans on the pleopods. This represents the first record of a symbiotic interaction between a tantulocarid and an amphipod for the Southern Ocean.

Distributional records of Antarctic and sub-Antarctic Ophiuroidea from samples curated at the Italian National Antarctic Museum (MNA): check-list update of the group in the Terra Nova Bay area (Ross Sea) and launch of the MNA 3D model ‘virtual gallery’

Abstract The distributional records of Ophiuroidea stored at the Italian National Antarctic Museum (MNA, Section of Genoa) are presented, corresponding to 1595 individuals that belong to 35 species and 17 genera. Specimens were collected in 106 different sampling stations at depths ranging from 21 to 1652 m in the framework of 14 Antarctic expeditions to the Ross Sea, one to the Antarctic Peninsula, and one to the Falkland Islands (Islas Malvinas). Three species, Amphiura joubini Koehler, 1912, Amphiura (Amphiura) angularis Lyman, 1879, and Ophiura flexibilis (Koehler, 1911), are reported as new records for the Terra Nova Bay area, whose check-list of species increases from 15 to 18 species. The determination of these three new records was based both on morphological identification and molecular analyses (COI barcoding). Some of the genetically characterised specimens were also documented through photogrammetry and micro-computed tomography and represent the first bulk of 3D models that will be available through the MNA and Sketchfab websites, both for research and educational purposes.

First record of living Acesta (Mollusca: Bivalvia) from an Antarctic seamount

The genus Acesta H. Adams & A. Adams, 1858 (Fam. Limidae) comprises species mainly occurring in the deep sea on hard substrates or canyon walls (Johnson et al. 2013), where hydrodynamic conditions enhance the supply of suspended food. During a survey of Scott and Admiralty seamounts as part of the New Zealand IPY-CAML expedition in 2008, a number of new records and new species were documented (e.g., Bowden et al. 2011). Here we report on the finding of a single living specimen of Acesta sp. (station 207, Scott B seamount) and several loose valves, both recent and subfossil at seafloor photographic stations 198, 202, 207 (Scott B seamount), 219 (Scott A seamount) and of a single valve at epibenthic sled station 256 (Scott I seamount) (Fig. 1). Until now, living Acesta spp. were reported to occur only in subantarctic areas such as Marion and Prince Edward islands (~46°S; Branch et al. 1991) and around Campbell (~53°S) and Macquarie (~56°S) islands (Marshall 2001). The Acesta sp. here documented is similar in outline to A. saginata Marshall 2001, which occurs south of New Zealand. However, marked differences in sculpture of the unique, slightly worn valve available for study suggest that the two species are different, but could be related due to their geographical proximity. More material from Antarctic seamounts would be needed to definitely assess the status of the Antarctic counterpart. Indeed, our records represent the first evidence of a living Acesta sp. in true Antarctic waters, south of the Polar Front, at 67-68°S. Previously, the genus had been reported from Antarctica only as a fossil in Cretaceous to Eocene sedimentary deposits of the La Meseta Formation on Seymour Island, Antarctic Peninsula (Stilwell and Gazdzichi 1998). This finding provides some support for the hypothesis that Ross Sea seamounts may have served as a refuge during glaciations (Bowden et al. 2011), allowing the survival of life forms that have gone extinct in the high Antarctic. Communicated by V. Urgorri

Incidental cleaning of crinoids by juveniles of Bodianus anthioides (Bennett, 1831) (Labridae) in the Red Sea

The fish family Labridae consists of over 500 species, several of which are obligate or facultative cleaners that remove parasites from their hosts, generally other fishes (Wilson and Wilson 1985), but rarely also from invertebrates. This paper reports on the cleaning activity of juveniles of Bodianus anthioides (Bennett, 1831) on crinoids in the Red Sea. During a dive undertaken at dusk, at Marsa Shagra (20 Km north of Marsa Alam, Red Sea, Egypt), the emergence of three specimens of the crinoid Lamprometra kluzingeri (Hartlaub, 1890) which left their daytime shelters to occupy nocturnal perches and collect plankton (Rutman and Fishelson 1969) was observed. As soon as they stabilized on the top of coral colonies, a juvenile of B. anthioides approached the crinoids and started a close inspection of their arms (Fig. 1a). The fish moved around the crinoids repeatedly, for about 3 minutes, removing several undetermined food items from each side of the arms’ pinnules (Fig. 1b–c). During this activity, crinoids did not react to the fish. B. anthioides is a common Indo-Pacific reef fish (Gomon 2006), and it has been observed in the Red Sea that juveniles of this species can serve as facultative fish cleaners (Bshary 2003). The present observation suggests that juveniles of this species may also integrate their diet opportunistically by targeting crinoids, which may host several other invertebrates, especially copepods (Fishelson 1974). As crinoids were involuntary ‘clients’, and no injury to their arms was observed, this kind of cleaning symbiosis can reasonably be considered as an example of incidental cleaning (Côté 2000). Although, the nature of the removed food item is unknown, it is however possible to exclude both kleptocommensal or commensal behaviour of B. anthioides for several reasons. Firstly, due to the mismatch between the diel activity patterns of the two species, Labridae typically being diurnal (Helfman et al. 1997) and crinoids nocturnal. In addition, the crinoids had just emerged and had not started yet to collect food. Other evidence lies in the fact that some items were removed by the fish from the external side of the pinnules (Fig. 1c), where no food is concentrated by crinoids and, more generally, by the fact that planktonic food has never been recorded in B. anthioides gut content analysis (Gomon 2006). The behaviour we observed therefore suggests not a stable partnership, but rather an opportunistic one which may occur during the twilight changeover (Helfman et al. 1997), when diel activities the two partners overlap for some minutes.

Porifera collection of the Italian National Antarctic Museum (MNA), with an updated checklist from Terra Nova Bay (Ross Sea)

Abstract This new dataset presents occurrence data for Porifera collected in the Ross Sea, mainly in the Terra Nova Bay area, and curated at the Italian National Antarctic Museum (MNA, section of Genoa). Specimens were collected in 331 different sampling stations at depths ranging from 17 to 1,100 meters in the framework of 17 different Italian Antarctic expeditions funded by the Italian National Antarctic Research Program (PNRA). A total of 807 specimens, belonging to 144 morphospecies (i.e., 95 taxa identified at species level and 49 classified at least at the genus level) is included in the dataset. Nearly half (45%) of the species reported here correspond to species already known for Terra Nova Bay. Out of the remaining 55% previously unknown records, under a third (~29%) were classified at the species level, while over a quarter (~26%) were ascribed to the genus level only and these would require further study. All vouchers are permanently curated at the MNA and are available for study to the scientific community. A 3D model of an uncommon species from the Ross Sea, i.e. Tethyopsisbrondstedi (Burton, 1929), is also presented and will be made available for outreach purposes.