MORBILLIVIRUS INFECTION IN BOTTLENOSE DOLPHINS: EVIDENCE FOR RECURRENT EPIZOOTICS IN THE WESTERN ATLANTIC AND GULF OF MEXICO

Morbillivirus infection is widespread among odontocetes of the western Atlantic and Gulf of Mexico. Serologic evidence of infection in bottlenose dolphins, Tursiops truncatus , was first detected during an epizootic along the mid-Atlantic coast in 1987. Here, we report recurrent epizootics in the coastal dolphin population since at least the early 1980s based on serological surveys and regional stranding frequencies. The first observed epizootic of this series occurred in the Indian and Banana Rivers in 1982 and was followed by others on the mid-Atlantic coast in 1987–1988 and in the Gulf of Mexico between 1992 and 1994. This temporal pattern of infection is likely facilitated by the population size and its fragmentation into relatively discrete coastal communities. Introduction of morbillivirus into a community with a sufficient number of naive hosts may precipitate an epizootic, depending on the potential for transmission within the group. Propagation of an epizootic along the coast is probably determined by frequency of contact between adjacent communities and seasonal migrations.
Morbillivirus antibodies were also detected in serum from offshore bottlenose dolphins. The sero-prevalence in the latter may be higher than in coastal dolphins because of their close association with enzootically infected pilot whales ( Globicephala spp.). Occasional contact between offshore and coastal dolphins may provide an epizootiologic link between pilot whales and coastal dolphin communities.     

A KINEMATIC STUDY OF SUCTION FEEDING AND ASSOCIATED BEHAVIOR IN THE LONG-FINNED PILOT WHALE, GLOBICEPHALA MELAS (TRAILL)

Analysis of videotaped feeding sequences provides novel documentation of suction feeding in captive juvenile long-finned pilot whales ( Globicephala melas ). Swimming and stationary whales were videotaped while feeding at the surface, mid-water, and bottom. The ingestion sequence includes a preparatory phase with partial gape followed by jaw opening and rapid hyoid depression to suck in prey at a mean distance of 14 cm (duration 90 msec), although prey were taken from much greater distances. Depression and retraction of the large, piston-like tongue generate negative intraoral pressures for prey capture and ingestion. Food was normally ingested without grasping by teeth yet was manipulated with lingual, hyoid, and mandibular movement for realignment; suction was then used to transport prey into the oropharynx. Whales frequently rolled or inverted before taking prey, presumably to avoid grasping and repositioning. Prey were sucked off the bottom or sides of the pool without direct contact; lateral suction was used to ingest items from the sides of the mouth.     

THE USE OF NATURAL MARKINGS IN STUDIES OF LONG-FINNED PILOT WHALES (GLOBICEPHALA MELAS)

Photo-identification using natural markings has been used for pilot whale ( Globicephala melas ) studies. However, none of these studies investigated the reliability of the marks used. To identify which mark types are reliable and which could improve the method, fifteen mark types, and their distribution within the population, were described. The rates of gain and loss of each mark type were calculated and the variability in visibility was investigated. Although the mark types associated with the current photo-identification method, the notch and the protruding piece, appear to be permanent, they allowed us to identify only 33% of our sample. The prevalence of all but two mark types is independent of the identifiability of a photograph. One of these is already used in the current photo-identification method. This independence indicates that the proportion of the population that is currently identifiable does not differ from the rest of the population in its susceptibility to factors causing marks, such as predation, and thus appears to be representative of the whole population. Using saddle patches in combination with the current photo-identification method would double the percentage of the identifiable individuals. However, due to limitations of matching software, the current method is easier to use.     

THE NORTHEASTERN ALBORAN SEA, AN IMPORTANT BREEDING AND FEEDING GROUND FOR THE LONG-FINNED PILOT WHALE (GLOBICEPHALA MELAS) IN THE MEDITERRANEAN SEA

Little is known about the long-finned pilot whale's population size, structure, distribution, and dynamics in the Western Mediterranean basin. The research region covered since 1992 in southeast Spain, at the edge of the Alboran Sea, is considered an important oceanographic transition zone between the Mediterranean and the Atlantic Ocean. The research ship Toftevaag carried out surveys covering a total of 10,173 nmi (18,840 km) from April to September each year, 1992-1997, all years pooled. Effort for ten-by-ten-mile quadrants was stratified by depth and sea state to ascertain encounter rates. Tracking was used together with photo-identification of animals to analyze home range of groups. Behavior was recorded ad libitum , and underwater video taping was used to analyze specific behavior patterns. One hundred and nine sightings of pilot whales were made. The average group size was 41.4 ± 58.4, ranging from 1 to 350. The average depth at encounters was 848.7 ± 281.2 m ranging from 300 to 1,800 m. Compatison of results for encounter rate and group size with those for other Mediterranean regions, together with site fidelity shown by photo-identification and observations of reproductive behavior, reflect the importance of the Alboran Sea to the species in the Mediterranean.     

STOMACH CONTENTS OF LONG-FINNED PILOT WHALES (GLOBICEPHALA MELAS) STRANDED ON THE U.S. MID-ATLANTIC COAST

Ten prey taxa were recorded from the stomach contents of eight long-finned pilot whales ( Globicepbala melas ) independently stranded along the U.S. mid-Atlantic coast. Relative importance of prey species was determined by methods that incorporate prey frequencies of occurrence, proportions of numerical abundance, and proportions of reconstructed mass. Separate analyses of trace (free, durable body parts representing well-digested prey items) and non-trace (relatively intact prey specimens) food material were conducted in order to address biases caused by differential rates of digestion and passage through the gastrointestinal tract. Different measures of prey importance yielded varying results, but the long-finned squid ( Loligo pealei ) was the most important prey species regardless of how prey importance was defined. Fishes were relatively unimportant in the diet. Our results indicate that the diets of western North Atlantic long-finned pilot whales differ substantially from what has been previously reported in the literature and that results from food-habits studies that utilize different techniques may not be comparable.     

SYSTEMATICS OF ANADYOMENE SPECIES (ANADYOMENACEAE,CHLOROPHYTA) IN THE TROPICAL WESTERN ATLANTIC1

Three new species of Anadyomene are described. Anadyomene lacerata has pinnately branched veins and a unique lacerated margin formed by elongated vein cells. Anadyomene linkiana consists of a perforate blade arising by polychotomous branching from a distinct stripe, and A. howei has an eperforate, delicate blade of polychotomously branched cells and a smooth margin of elongated vein cells. Distinguishing features of the five previously described species are clarified, and all eight taxa are illustrated. Observations in the field and from more than 400 herbarium specimens form the basis for a discussion of Indo-Pacific affinities, ecological adaptations, cell division, reproduction, and ordinal status. A phylogenetic analysis based on 17 equally weighted characters produced a cladistic gradation, indicating that Anadyomene is a monophyletic genus. The most basal species (A. saldanhae, A. linkiana, A. howei, A. menziesii) show only polychotomous branching. In contrast, the distal group (A. pavonina, A. stellata, A. rhizoidifera, A. lacerata) have pinnate interstitial cells along the veins in addition to polychotomous branching at the vein apices.