1. Wochenbericht POS520

Investigating deep water column biodiversity and ecology of the Cape Verde Islands Weekly report 14/2/2018-21/2/201

2. Wochenbericht POS532

11/2/2019-17/2/201

2. Wochenbericht POS532

11/2/2019-17/2/201

Mating Behavior of a Deep-Sea Squid Revealed by in situ Videography and the Study of Archived Specimens

The mating behavior of deep-sea squids is shrouded in mystery. The squids for which mating has been observed use a hectocotylus, a modified arm, for the transfer of sperm packets called spermatophores. However, many deep-sea squid species lack a hectocotylus. We present the first in situ observations of mating behavior in a deep-sea squid that has no hectocotylus but instead uses an elongated terminal organ for the transfer of spermatangia, which are released from the spermatophores and burrow deeply into the female tissue. With remotely operated vehicles (ROVs), we observed two mating pairs of the deep-sea squid Pholidoteuthis adami in the Gulf of Mexico. The male adopted a peculiar position during mating, with its ventral side up and its posterior mantle above the female's head. While the male held the female in what looked like a firm grip, we observed the long terminal organ extending through the funnel of the male, contacting the female dorsal mantle. Examinations of museum specimens show that spermatangia burrow from the outer dorsal mantle into the inner dorsal mantle. This combination of serendipitous in situ observations and archived specimens can be a powerful tool for understanding the behavior of deep-sea animals

The giant deep-sea octopus Haliphron atlanticus forages on gelatinous fauna

Feeding strategies and predator-prey interactions of many deep-sea pelagic organisms are still unknown. This is also true for pelagic cephalopods, some of which are very abundant in oceanic ecosystems and which are known for their elaborate behaviors and central role in many foodwebs. We report on the first observations of the giant deep-sea octopus Haliphron atlanticus with prey. Using remotely operated vehicles, we saw these giant octopods holding medusae in their arms. One of the medusae could be identified as Phacellophora camtschatica (the egg-yolk jelly). Stomach content analysis confirmed predation on cnidarians and gelatinous organisms. The relationship between medusae and H. atlanticus is discussed, also in comparison with other species of the Argonautoidea, all of which have close relationships with gelatinous zooplankto

Cruise Summary Report POS532

The aim of this cruise was to investigate the role of gelatinous zooplankton in the biological carbon pump, i.e. transporting carbon from the surface into the deep sea. In addition, the cruise aimed to better understand the biodiversity, abundance and distribution of pelagic fauna including nekton and macrozooplankton in the Cape Verde region, and to provide one of the first bottom surveys in the coastal deep seas of Cape Verde. The latter resulting in new faunal records and biological observations. We used the manned submersible JAGO (17 dives), the towed camera system PELAGIOS (13 deployments), and two kinds of multinet (midi and maxi) (14 and 7 hauls respectively). Biological specimens were preserved as voucher specimens and samples were obtained for DNA barcoding. CTD sampling was performed to collect hydrographic data. We also collected water samples for environmental DNA and to analyze these samples in the lab for traces of deep-sea organisms such cephalopods. To quantify pelagic biomass and track migration via bioacoustics we used an EK80. Elaborate physical sampling around the islands was performed using CTD and ADCP. In the leeway of the islands Santo Antão and Fogo we performed mesopelagic stations (1000 m) and bathypelagic stations (3000 m) using the mentioned instruments. An offshore mesoscale eddy was sampled with all our oceanographic instruments. Additionally we performed a full oceanographic and biological sampling at the Cape Verde Ocean Observatory, north of Sao Vicente

2. Wochenbericht POS520

Investigating deep water column biodiversity and ecology of the Cape Verde Islands Weekly report 21/2/2018-1/3/201

Trace element analysis reveals bioaccumulation in the squid Gonatus fabricii from polar regions of the Atlantic Ocean

The boreoatlantic gonate squid (Gonatus fabricii) represents important prey for top predators—such as marine mammals, seabirds and fish—and is also an efficient predator of crustaceans and fish. Gonatus fabricii is the most abundant cephalopod in the northern Atlantic and Arctic Ocean but the trace element accumulation of this ecologically important species is unknown. In this study, trace element concentrations (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn) were analysed from the mantle muscle and the digestive gland tissue of juveniles, adult females, and adult males that were captured south of Disko Island off West-Greenland. To assess the feeding habitat and trophic position of this species, stable isotopes of carbon (δ13C) and nitrogen (δ15N) were measured in their muscle tissue. Mercury concentrations were positively correlated with size (mantle length) and trophic position. The Hg/Se ratio was assessed because Se has been suggested to play a protective role against Hg toxicity and showed a molar surplus of Se relative to Hg. Cadmium concentrations in the digestive gland were negatively correlated with size and trophic position (δ15N), which suggested a dietary shift from Cd-rich crustaceans towards Cd-poor fish during ontogeny. This study provides trace element concentration data for G. fabricii from Greenlandic waters, which represents baseline data for a northern cephalopod species. Within West-Greenland waters, G. fabricii appears to be an important vector for the transfer of Cd in the Arctic pelagic food web

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Sperm storage and mating in the deep-sea squid Taningia danae Joubin, 1931 (Oegopsida:Octopoteuthidae)

Spermatangium implantation is reported in the large oceanic squid Taningia danae, based on ten mated females from the stomachs of sperm whales. Implanted spermatangia were located in the mantle, head and neck (on both sides) or above the nuchal cartilage, under the neck collar and were often associated with incisions. These cuts ranged from 30 to 65 mm in length and were probably made by males, using the beak or arm hooks. This is the first time wounds facilitating spermatangium storage have been observed in the internal muscle layers (rather than external, as observed in some other species of squid). The implications of these observations for the mating behavior of the rarely encountered squid T. danae are discussed