Álvaro Roura

Nyctiphanes couchii as intermediate host for the acanthocephalan Bolbosoma balaenae in temperate waters of the NE Atlantic

Cystacanths of the acanthocephalan Bolbosoma balaenae (Gmelin, 1790) were found encapsulated in the cephalothorax of the euphausiid Nyctiphanes couchii (Bell, 1853) from temperate waters in the NE Atlantic Ocean. Euphausiids were caught in locations outside the Ría de Vigo in Galicia, NW Spain, and prevalence of infection was up to 0.1%. The parasite was identified by morphological characters. Cystacanths were 8.09 ± 2.25 mm total length (mean ± SD) and had proboscises that consisted of 22 to 24 longitudinal rows of hooks, each of which had 8 or 9 hooks per row including 2 or 3 rootless ones in the proboscis base and 1 field of small hooks in the prebulbar part. Phylogenetic analyses of 18S rDNA and cytocrome c oxidase subunit I revealed a close relationship with other taxa of the family Polymorphidae (Meyer, 1931). The results extend northwards ot the known distribution of B. balaenae. Taxonomic affiliation of parasites and trophic ecology in the sampling area suggest that N. couchii is the intermediate host for B. balenae, and we suggest that the whales Balaenoptera physalus (Linnaeus, 1758) and B. acutorostrata (Lacepède, 1804) are its definitive hosts. This life cycle is probably completed with or without paratenic hosts.

Nyctiphanes couchii as intermediate host for Rhadinorhynchus sp. (Acanthocephala, Echinorhynchidae) from NW Iberian Peninsula waters

In the mesozooplanktonic community of the coastal upwelling system of the Ría de Vigo (NW Spain), the euphausiid Nyctiphanes couchii has been identified for the first time in temperate waters of the NE Atlantic as the intermediate host for cystacanths of Rhadinorhynchus sp. Parasites were identified using morphological characters described in 20 cystacanths. The hooks of the proboscis were arranged in 14 rows of 26 hooks each, while the hooks of the basal circle were only slightly erected and were longer than remaining spines. A maximum-likelihood estimation (ML) tree inferred from the 18S rRNA data set of Palaeacantocephala revealed that our specimens belong to a highly supported clade with Rhadinorhynchus sp., Pararhadinorhynchus sp. and Transvena annulospinosa. Nonetheless, our morphological and phylogenetic analyses suggested that the status of Rhadinorhynchus pristis should be re-examined. The prevalences of parasites were 0.0019% and 0.0001% for frontal and coastal summer communities, and 0.0068% and 0.0008% for coastal and oceanic autumn communities, respectively. The presence of these cystacanths in different mesozooplankton communities throughout the study suggests that the recruitment of parasites may be affected by the oceanography.

Cannibalistic behavior of octopus (Octopus vulgaris) in the wild.

The first description of cannibalism in wild adult Octopus vulgaris is presented from 3 observations made in the Ría de Vigo (NW Spain), which were filmed by scuba divers. These records document common traits in cannibalistic behavior: (a) it was intercohort cannibalism; (b) attacks were made by both males and females; (c) in 2 of the records, the prey were transported to the den, which was covered with stones of different sizes; (d) the predator started to eat the tip of the arms of its prey; (e) predation on conspecifics occurred even if there were other abundant prey available (i.e., mussels); and (f) the prey/predator weight ratio in the 3 cases ranged from 20% to 25% body weight. The relationships between this behavior and sex, defense of territory, energy balance, food shortage, competition and predation, as well as how the attacker kills its victim are discussed.

Sperm ultrastructure in Bathypolypus bairdii and B. sponsalis (Cephalopoda: Octopoda)

A morphological comparison of the spermatozoa of the octopods Bathypolypus bairdii and B. sponsalis has been carried out by electron microscopy. Although the mature spermatozoon of B. bairdii is longer and thinner than that of B. sponsalis, its general ultrastructure is similar except for some minor differences. Their characteristic acrosomes, described here for the first time, consist of a periodically banded cone surrounded by a double helix whose arrangement has been defined by a numeric expression. The plasma membrane of sponsalis that surrounds the acrosome has many projections filled with abundant granular cytoplasm, which appears as a star‐shaped acrosome in cross‐section. The mitochondrial sheath contains 9–11 mitochondria in bairdii but only 9 in sponsalis. A comparison with other Octopodidae shows that the nucleus of both species is the largest ever seen. Our results support the capability of sperm morphology to discriminate between species and could even discern at higher taxonomic levels. J. Morphol., 2010.

Isolation and molecular identification of the scuticociliate Porpostoma notata Moebius, 1888 from moribund reared Hippocampus hippocampus (L.) seahorses, by amplification of the SSU rRNA gene sequences

The Scuticociliatia subclass includes hundreds of species with mostly uncertain phylogenetic relationships and classifications ( Alvarez-Pellitero et al. 2004). On the basis of morphological and morphogenetical data, Lynn (2008) recognized three Scuticociliatia orders: Philasterida, Thigmotrichida and Pleuronematida. They are endemic to worldwide coastal ecosystems where they thrive either as freeliving organisms or parasitic to aquatic animals. In fact, these facultative ciliated protists can occasionally become pathogenic for the hosts, leading to scuticociliatosis in some species of fish, crustaceans and molluscs (Iglesias et al. 2001). The scuticociliates Uronema marinum Dujardin, Miamiensis avidus Thompson & Moewus, and Philasterides dicentrarchi Dragesco have been recognized as causative agents of mass mortalities in some cultured marine fishes such as turbot Scophthalmus maximus (L.) (Iglesias et al. 2001), sea bass Dicentrarchus labrax L. (Dragesco et al. 1995) and olive flounder Paralichthys olivaceus (Temminck & Schlegel) (Kim et al. 2004), among others. In seahorses, ciliates have been reported to cause outbreaks of scuticociliatosis, with high mortality rates in Hippocampus erectus Perry (Cheung, Nigrelli & Ruggieri 1980), Hippocampus trimaculatus Leach (Meng & Yu 1985) and Hippocampus kuda Bleeker (Shin et al. 2011). Indeed, the ciliate P. dicentrarchi has been recognized as the main cause of mortality in captive reared seahorses H. kuda (Shin et al. 2011). P. dicentrarchi infections in syngnathids are usually accompanied by skin ulcerations, abdominal distension and central nervous anomalies. Lethargy, anorexia and rapid death have been also related to P. dicentarchi infections (Umehara, Kosuga & Hirose 2003). Seahorses have a ‘data deficient’ status on the IUCN Red List of Threatened Species (IUCN 2012), and all seahorse species are listed in CITES Appendix II. Due to this situation, seahorse research and rearing have substantially increased in the last decades (Planas et al. 2009). Consequently, a comprehensive identification of associated ectoor endoparasites can help to establish effective preventive treatments in reared seahorses. On this regard, the present work describes the isolation and molecular identification of the scuticociliate Porpostoma notata Moebius, 1888 in moribund Hippocampus hippocampus juveniles reared in captivity, from a batch with mass mortality. A pregnant male of H. hippocampus was captured by scuba diving in Toralla Island (Galicia, NW Spain) in 2011 and conveniently transferred to the facilities at the IIM-CSIC in Vigo. A batch of 784 newborn of 14.5 mm 2 in length and 3 mg 1.7 in weight was released and reared under controlled conditions, as reported by Planas et al. (2009). High survival rates were recorded Correspondence C Ofelio, Instituto de Investigaciones Marinas (IIM-CSIC), Eduardo Cabello 6, 36208 Vigo, Spain (email: claudiaofelio@gmail.com)

The black-pygmy mussel Limnoperna securis in Galician Rias (north-eastern Atlantic): new records and first evidence of larval stages predation by copepods

The presence of the non-indigenous species, the black-pygmy mussel Limnoperna securis , was surveyed for the first time in the Rias of Pontevedra and Arousa, areas adjacent to the first location (Ria of Vigo) of this potential invader in Atlantic waters. Molecular identification of the mussels was conducted by polymerase chain reaction amplification and sequencing of nuclear and mitochondrial genes. This paper describes for the first time the species in the Ria of Pontevedra, confirming that this invader was absent in an intense shellfish farming area of the Ria of Arousa (Galicia, north-western Spain). Field sampling revealed that relatively high concentrations of this mytilid bivalve have colonized some localities of the inner part of the Ria of Pontevedra located in brackish waters. A comparison between population densities, size and substrate preference of L. securis in the Rias of Pontevedra and Vigo was conducted. Dispersion capacity of L. securis is discussed based on molecular detection of larval stages in the stomach contents of the copepod Centropages typicus coupled with physical oceanography of the southern Galician Rias. The invasive role of L. securis is also discussed in the context of the bissus secretion and attachment strength, ecological tolerance of the species, and the recent finding of settlements of this species on numerous colonies of the economically important blue mussel Mytilus galloprovincialis .

Prey Capture, Ingestion, and Digestion Dynamics of Octopus vulgaris Paralarvae Fed Live Zooplankton

Octopus vulgaris is a species of great interest in research areas such as neurobiology, ethology, and ecology but also a candidate species for aquaculture as a food resource and for alleviating the fishing pressure on its wild populations. This study aimed to characterize the predatory behavior of O. vulgaris paralarvae and to quantify their digestive activity. Those processes were affordable using the video-recording analysis of 3 days post-hatching (dph), mantle-transparent paralarvae feeding on 18 types of live zooplanktonic prey. We show for the first time in a live cephalopod that octopus paralarvae attack, immobilize, drill, and ingest live cladocerans and copepods with 100% efficiency, which decreases dramatically to 60% on decapod prey (Pisidia longicornis). The majority (85%) of successful attacks targeted the prey cephalothorax while unsuccessful attacks either targeted the dorsal cephalothorax or involved prey defensive strategies (e.g., juvenile crab megalopae) or prey protected by thick carapaces (e.g., gammaridae amphipods). After immobilization, the beak, the buccal mass and the radula were involved in exoskeleton penetration and content ingestion. Ingestion time of prey content was rapid for copepods and cladocerans (73.13 ± 23.34 s) but much slower for decapod zoeae and euphausiids (152.49 ± 29.40 s). Total contact time with prey was always <5 min. Contrary to the conventional view of crop filling dynamics observed in adult O. vulgaris, food accumulated first in the stomach of paralarvae and the crop filled after the stomach volume plateaued. Peristaltic crop contractions (~18/min) moved food into the stomach (contractions ~30/min) from where it passed to the caecum. Pigmented food particles were seen to enter the digestive gland, 312 ± 32 s after the crop reached its maximum volume. Digestive tract contents passed into the terminal intestine by peristalsis (contraction frequency ~50/min) and defaecation was accompanied by an increased frequency of mantle contractions. Current results provide novel insights into both, O. vulgaris paralarvae—live prey capture strategies and the physiological mechanisms following ingestion, providing key information required to develop an effective rearing protocol for O. vulgaris paralarvae.

Morphological variability of the rare bush-club squid Batoteuthis (Cephalopoda, Batoteuthidae)?

A specimen of Batoteuthidae was caught during the research cruise ATLANTIS 2009 on 21 March 2009 at 45o09.51’ S 45o08.07’ S 59o29.04’ W 59o27.98’W (Patagonian slope), depth 1195-1221 m. This specimen is a juvenile male, 105 mm mantle length. It is the largest Batoteuthis with complete tentacles captured to date. It shares the main diagnostic characters of the family. We compared that specimen with the types of Batoteuthis skolops, the only known species in the family. Our specimen has several differences from the types (lower tail length index, different fin shape, arm length indices 3-4 times longer, tentacles and clubs 4 or 5 times longer than the types, distinct arrangement of suckers in ventral arms, and different number, size and disposition of suckers in tentacular clubs) suggesting that it might be a different species. However, we cannot refute the alternative hypothesis that the differences are ontogenic. Until additional good specimens become available or molecular analyses are undertaken, we recommend a conservative approach of considering our specimen tentatively to be a growth form of Batoteuthis skolops.

Sperm ultrastructure of the hydrothermal vent Octopod Vulcanoctopus hydrothermalis

Sperm ultrastructure of the deep‐sea hydrothermal vent octopod Vulcanoctopus hydrothermalis has been carried out by transmission electron microscopy. Spermatozoa of this species have the shortest head observed so far in octopodids. The acrosome possesses a helix with six gyres. The rod‐shaped nucleus is short and wide in relation with other octopodids. Noteworthy features along the nucleus are the regularly disposed dense bands of cytoplasm, which have not been observed before in octopodids. The nuclear fossa is very short and wavy. Mitochondrial sheath has 10 elongated mitochondria running parallel to the axoneme‐coarse fibers complex. Sperm morphology of V. hydrothermalis resembles that of Enteroctopus dofleini, suggesting a close phylogenetic relationship. J. Morphol. 271:932–936, 2010.