Mercedes Fernández

Dolphin morbillivirus epizootic resurgence, Mediterranean Sea.

In July 2007, >100 striped dolphins, Stenella coeruleoalba, were found dead along the coast of the Spanish Mediterranean. Of 10 dolphins tested, 7 were positive for a virus strain closely related to the dolphin morbillivirus that was isolated during a previous epizootic in 1990.

Descriptions of some unusual digeneans from Boops boops L. (Sparidae) and a complete checklist of its metazoan parasites

Six species of digeneans, including three new host records, are described from the bogue Boops boops off the Spanish NE Atlantic and the Mediterranean coasts. The species involved are: Robphildollfusium martinezgomezi López-Román, Gijón-Botella, Kim & Vilca-Choque, 1992, Magnibursatus caudofilamentosa (Reimer, 1971) Gibson & Køie, 1991, Lepocreadium album Stossich, 1890, Steringotrema pagelli (van Beneden, 1871) Odhner, 1911, Tetrochetus coryphaenae Yamaguti, 1934 and Stephanostomum euzeti Bartoli & Bray, 2004 (metacercaria). B.␣boops is a new host for 11 metazoan parasites (six digeneans, three acanthocephalans, one copepod and one isopod) recovered in this study. These are reported and incorporated into a complete checklist of the metazoan parasites of B. boops throughout its distributional range. It comprises summarised information for 67 species in 260 host-parasite records and includes the name of the parasite species, the locality of the host, and the author and date of the published record. The taxonomy is updated and annotations are made on the validity of the records and synonymies.

Molecular phylogeny of the families Campulidae and Nasitrematidae (Trematoda) based on mtDNA sequence comparison

Historically, the systematic arrangement of the genera within the family Campulidae, and its relationship with its allied family Nasitrematidae have been rather confused, particularly because only adult morphology has been available to classical taxonomic analysis. In this paper we provide a partial phylogeny of the genera of these families based on mtDNA from five campulid species: Campula oblonga, Zalophotrema atlanticum, Hadwenius tursionis, Oschmarinella rochebruni and Orthosplanchnus fraterculus; and one nasitrematid, Nasitrema globicephalae. Fasciola hepatica and Dicrocoelium dendriticum were used as outgroups. Maximum parsimony and neighbour-joining methods were applied. Both methods produced similar trees where H. tursionis appeared as the basal campulid, with a sequential divergence of Z. atlanticum, N. globicephalae, C. oblonga, O. rochebruni and O. fraterculus. Results suggest that Nasitrematidae as defined should loose its familial status and the current subfamilial division of the family Campulidae is at least partly artificial and should not be maintained.

Living Together: The Parasites of Marine Mammals

The reader may wonder why, within a book of biology and conservation of marine mammals, a chapter should be devoted to their parasites. There are four fundamental reasons. First, parasites represent a substantial but neglected facet of biodiversity that still has to be evaluated in detail (Windsor, 1995; Hoberg, 1997; Brooks and Hoberg, 2000. Perception of parasites among the public are negative and, thus, it may be hard for politicians to justify expenditure in conservation programmes of such organisms. However, many of the reasons advanced for conserving biodiversity or saving individual species also apply to parasites (Marcogliese and Price, 1997; Gompper and Williams, 1998). One fundamental point from this conservation perspective is that the evolutionary fate of parasites is linked to that of their hosts (Stork and Lyal, 1993). For instance, the eventual extinction of the highly endangered Mediterranean monk seal Monachus monachus would also result in that of its host-specific sucking louse Lepidophthirus piriformis (Fig. 1b). Second, parasites cause disease, which may have considerable impact on marine mammal populations (Harwood and Hall, 1990). Scientists have come to realise this particularly after the recent die-offs caused by morbilliviruses (see Domingo et al., this volume). However, these epizootic outbreaks represent the most dramatic, but by no means the only, example of parasite-induced mortality in marine mammal populations (see Section 3 below).

Independent host switching events by digenean parasites of cetaceans inferred from ribosomal DNA.

Cetaceans harbour a unique fauna of digeneans whose origin and relationships have sparked considerable debate during recent decades. Disparity in the species reported indicates that they do not share close affinities, but their unusual morphology has made their taxonomic identities and phylogenetic positions uncertain. Here we use sequence data to investigate the phylogenetic relationships of the main species of flukes infecting cetaceans. We sequenced the 18S, 28S and internal transcribed spacer 2 rDNA of digenean species representing all known families reported from cetaceans: Braunina cordiformis (Brauninidae), Ogmogaster antarcticus (Notocotylidae), Pholeter gastrophilus (Heterophyidae), and Campula oblonga, Nasitrema sp. and Oschmarinella rochebruni (Brachycladiidae). The phylogenetic position of the taxa was estimated by Bayesian inference and maximum likelihood incorporating published sequences of 177 species of Digenea. Further Bayesian and maximum likelihood analyses were performed with sequences of 14 Heterophyidae and Opisthorchiidae taxa, incorporating new sequences of P. gastrophilus. Species nominally assigned to the Brachycladiidae formed a clade that was embedded among species of the Acanthocolpidae, thus making the latter family paraphyletic. Braunina cordiformis formed a sister lineage to the Strigeidae and Diplostomidae, whereas O. antarcticus was placed within the Notocotylidae, in agreement with the previous taxonomy of this genus. Similarly, P. gastrophilus was placed within the Heterophyidae as originally described. Our results suggest a paraphyletic relationship between the Heterophyidae and Opisthorchiidae, mirroring the uncertain taxonomic placement of P. gastrophilus, which has been assigned to both families in the past. The digenean families involved are parasites of fish-eating birds and mammals (i.e. Strigeidae, Diplostomidae and Heterophyidae), parasites of marine fish (i.e. Acanthocolpidae) and other herbivorous aquatic birds and mammals (i.e. Notocotylidae). The phylogenetic positions of these taxa indicate that the digenean fauna of cetaceans may have been acquired through independent host-capture events, with two clades showing subsequent diversification exclusively among marine mammals.

Parasites as indicators of social structure and stock identity of marine mammals

Abstract Introduction: the use of parasites as biological indicators of marine mammals has not yet received all the necessary attention. The aim of this review is to show the value of parasite data in studies of stock identity and social structure. Methods: the application of the technique to marine mammals is hampered by the lack of control over sampling conditions and the paucity of information about the biology of their parasites. Relevant criteria for, suitable parasite tags are discussed. Case studies: previous work on marine mammals is presented to illustrate the usefulness and limitations of parasite data. A study of pilot whales revealed that differences in helminth infections between two groups of pods conformed with previous evidence suggesting separate stocks. Other investigations have provided valuable information about behavioural features of marine mammals. Studies of whale-lice exemplify the advantages of using directly transmitted ectoparasites. Conclusions: the technique has so far proven more successful in behavioural than in population studies. However, parasite analyses have to the parasites may provide new tools for further studies

CONSTRUCTIONAL MORPHOLOGY AND MODE OF ATTACHMENT OF THE TRUNK OF CORYNOSOMA CETACEUM (ACANTHOCEPHALA : POLYMORPHIDAE)

Dead specimens of Corynosoma cetaceum were used to describe the trunk musculature of this species and to infer the use of the trunk as a secondary holdfast. Inferences were based on trunk muscle arrangement, changes in trunk shape, size and distribution of spines, and geometry of tegument thickness. The foretrunk of C. cetaceum is swollen and forms a spiny disk that is bent ventrally. The disk is flattened by several groups of muscles not described previously, which seem able to finely adjust the disk surface over the substratum. Disk attachment appears to be accomplished by two dorsal neck retractor muscles specialized in pulling the anchored proboscis into the foretrunk. This mechanism has been described in other acanthocephalans, becoming surprisingly efficient when used with a flattened, armed foretrunk. The ventrally spined hindtrunk requires force to move downwards in order to attach. A single ventral neck retractor muscle seems specialized in pulling the posterior trunk forward, inducing a downward force due to the muscles precise points of insertion. This mechanism necessarily generates ventral wrinkling that needs to be eliminated for the spiny surface to be functional. The trunk ventral muscles are apparently arranged so as to concentrate the “excess” of the tegument into a single fold, optimizing the use of the remaining surface for attachment. The size and distribution of spines, as well as the geometry of tegumental thickness, conform to these observations. Morphological changes, seemingly simple, such as structural bending, may have triggered a cascade of subtle modifications and new functions during acanthocephalan evolution, reflecting how morphological integration and novelty interact. J. Morphol. 241:237–249, 1999.

PARASITE COMMUNITIES OF COMMON DOLPHINS (DELPHINUS DELPHIS) FROM PATAGONIA: THE RELATION WITH HOST DISTRIBUTION AND DIET AND COMPARISON WITH SYMPATRIC HOSTS

We studied the helminths of 18 common dolphins, Delphinus delphis, from northern Patagonia. Parasites were found only in the gastrointestinal tract. Four species were in the stomach, the nematode Anisakis simplex, the acanthocephalan Corynosoma cetaceum, and the digeneans Braunina cordiformis and Pholeter gastrophilus, plus 1 digenean in the hepatopancreatic ducts, Oschmarinella rochebruni. Infection levels were low (0–155 parasites). Braunina cordiformis and C. cetaceum were the most prevalent species. Anisakis simplex was mainly concentrated in the forestomach, B. cordiformis in the main stomach, and C. cetaceum in the pyloric stomach. Component diversity was low and component evenness was intermediate. Infracommunity diversity was also low, and the mean evenness was higher than at the component community level. Low prevalence in common dolphins is consistent with parasite assemblages of other cetaceans off Patagonia. None of the parasites found is specific to this host species within the study area. We suggest that potential prey are probably important in parasite transmission in this and other dolphins from the Patagonian region.

Endoparasites of the blue whiting, Micromesistius poutassou from north-west Spain

The communities of metazoan endoparasites of blue whiting, Micromesistius poutassou, in waters of north-west Spain were analysed and a geographical comparison made with other localities. Four hundred blue whiting collected in July 1999 and September 2000 were examined for parasites, excluding the head and gills. Six species were found: Anisakis simplex s.l. (L3), A. physeteris (L3), Hysterothylacium aduncum (L2 and L3), Stephanostomum lophii (metacercaria), S. pristis (adult), and Prosorhynchus crucibulum (metacercaria). The latter is a new host record, and A. physeteris is reported for the first time in blue whiting from the north-east Atlantic. Host gender was not a significant predictor of abundance of any helminth species, and host length was only weakly and positively related to the abundance of A. simplex. Infracommunities were species-poor, with 56% of fish harbouring only one parasite species, and 92% up to two species. Infracommunities were strongly dominated by A. simplex (389 fish) or S. lophii (6 fish). Fish length or gender, and the year of capture, did not affect species richness nor the degree of dominance. There were no significant pair-wise associations between species. Infracommunities were basically composed of several allogenic parasites with different life histories that converge in the blue whiting through the local food web. The parasite fauna of blue whiting in the study area was poor and distinctive compared with that of other localities in the north-east North Atlantic. These peculiarities might primarily be related to the composition of the local community of definitive hosts, although there might also be some influence of the geographical distribution of parasites.

REDESCRIPTION OF ANTARCTOPHTHIRUS MICROCHIR (ANOPLURA: ECHINOPHTHIRIIDAE) FROM THE SOUTH AMERICAN SEA LION, OTARIA FLAVESCENS, FROM PATAGONIA, ARGENTINA

Abstract Antarctophthirus microchir was originally described from Phocarctos hookeri on the basis of 1 female and 1 male only. We redescribe adults and describe, for the first time, the 3 nymphal stages from specimens collected from Otaria flavescens from Patagonia, using light and scanning electron microscopy. The present material can be distinguished from other Antarctophthirus species by the presence of a fringe of setae on the back of the head, only present in Antarctophthirus trichechi and Antarctophthirus callorhini. However, A. trichechi also possess a prominent proboscis with large hooks, and A. callorhini presents less abundant and nonuniform abdominal scales in shape and size. Other differential features of A. microchir are the pattern of ovoid and uniform scales and longitudinal grooves in the surface of spines. Nymphal stage 1 differs from 2 and 3 mainly by the absence of scales and thorax without ventral spines or hairs. Nymphal stages 2 and 3 may be distinguished by the disposition of the occipital apophyses. Antarctophthirus microchir has been reported from 5 sea lion species from both hemispheres. Considering the conservative morphology, and ecological and evolutionary features of sucking lice, we raise the question of whether A. microchir from different sea lion hosts may represent a complex of cryptic species.