MITOCHONDRIAL DNA VARIABILITY OF STRIPED DOLPHINS (STENELLA COERULEOALBA) IN THE SPANISH MEDITERRANEAN WATERS

Frozen muscle samples from 44 striped dolphins stranded on the Spanish Mediterranean coasts from 1990 to 1993 have been studied by means of mitochondrial DNA (mtDNA) restriction site analysis. Thirty-five of these dolphins were affected by a die-off occurring during this time in the western Mediterranean Sea. The mtDNA from each dolphin was digested with 15 restriction endonucleases that recognized 61 different restriction sites. The specific location of these sites on the mitochondrial gene map allowed us to determine the distribution of variability along this molecule. From the restriction analysis, a total of 15 different composite patterns or haplotypes was obtained and their phylogenetic relationships established both by cladistic and phenetic methods.
Estimates of sequence divergence among the 15 haplotypes ranged from 0.148% to 0.919%. Haplotype diversity (average heterozygosity) obtained was 0.789, a high value compared to other available data on cetaceans, especially considering that only a small area of the distribution of the species has been sampled. Neither population subdivision nor any evidence of correlation between haplotype frequencies and temporal or geographic distribution of dolphins has been detected.     

AGE and SEX COMPOSITION OF THE STRIPED DOLPHIN DIE-OFF IN THE WESTERN MEDITERRANEAN

During the morbillivirus epizootic that affected the Mediterranean striped dolphins ( Stenella coeruleoalba )in 1990–1992, several thous and individuals are believed to have died. In order to determine the segments of the population that were affected by the event, the sex- and age-frequency distributions of the animals that were washed ashore on the Spanish coasts were studied. The age of the animals was determined by counting dentine growth layer groups in the teeth. The results obtained indicate that both sexes were affected similarly by the disease and that the population component that suffered the largest mortality was that of sexually mature individuals, although substantial mortality of calves, probably still dependent on their mothers, was also observed. Juveniles, in contrast, appeared to be only slightly affected by the epizootic. This pattern of mortality is not consistent with the epidemiology of morbillivirus infections previously observed in other mammals. Possible explanations of this particular age distribution include behavioral factors, increased susceptibility to the disease in adults due to the effects of pollution, high temperatures and decreased food availability, or allopatric geographical distribution of population components and, therefore, of their associated mortality.     

DIURNAL BEHAVIOR OF FREE-RANGING BOTTLENOSE DOLPHINS IN THE KVARNERIĆ (NORTHERN ADRIATIC SEA)1

The diurnal behavior of a bottlenose dolphin (Tursiops truncatus) community was observed from small inflatable craft between 1987 and 1994. Following a preliminary ad libitum study 11,839 3-min behavioral samples were recorded in 1991-1994. The behavioral budget showed a predominance (about 80%) of activities characterized by long (>30 sec) dives, considered to be largely related to prey search or feeding. Obvious foraging near the surface was observed rarely. The frequent following of trawlers (accounting for 4.6% of the behavioral budget) was indicative of the presence of alternative strategies for finding food. Yearly and seasonal behavioral variation-particularly in feeding-related and travel behaviors-was consistent with the hypothesis of behavioral flexibility as a response to environmental changes and fluctuating prey kind and availability. Yearly shifts in social behavior appeared to be partly influenced by breeding cycles. Groups engaged in feeding-related activities were significantly smaller than traveling or socializing groups, and dramatic interannual group-size shifts seemed to be largely affected by environmental variables, rather than being entirely determined by behavioral activity changes. The remarkable behavioral flexibility of this bottlenose dolphin community may contribute to its survival in the shifting environmental conditions of the northern Adriatic Sea. However, the high proportion of time consistently devoted to feeding-related activities, as compared to other areas, suggests that food resources in the Kvarneri? were not only highly variable but also depleted.     

Craniometric variation of some Mediterranean and Atlantic populations of Stenella coeruleoalba (Mammalia,Delphinidae): A three‐dimensional geometric morphometric analysis

The variability of cranial features of Atlantic and Mediterranean samples of Stenella coeruleoalba was examined using a three‐dimensional geometric morphometric approach. Data were collected on 79 skulls from the upper and middle Mediterranean Sea, the Atlantic French coasts, and Scotland. Three‐dimensional x, y, and z coordinates of 27 landmarks were recorded on each left half skull using a Microscribe 3‐D digitizer. All configurations were rotated, centered, and scaled, and residuals from the mean configuration were analyzed through multivariate analyses of variance. Mahalanobis distances among populations were used to evaluate phenetic relationships. Consensus configurations were compared to visualize shape differences among samples. Analyses revealed significant differences among populations, a clear distinction of the Scottish coasts dolphins from the other samples, and a closer relationship of the dolphins from the French coasts to the Mediterranean populations than to the Scottish one. Shape differences are mainly concentrated in the rostral and in the occipital regions of the skull. Phylogenetic and adaptive factors were invoked as possible causes of the variation patterns.     

SOCIAL ECOLOGY OF BOTTLENOSE DOLPHINS IN THE KVARNERIĆ (NORTHERN ADRIATIC SEA)

A bottlenose dolphin community was studied from small inflatable craft from 1987 to 1994 in a relatively large area (about 800 km²) east of the islands of Loˇsinj and Cres, northern Adriatic Sea. A total of 106 individuals were photoidentified based on natural permanent marks on their dorsal fins. Most of the dolphins were resighted on a regular basis, indicating a high level of year-round site fidelity, although their range was evidently greater than the chosen study area. Dolphin density was highly variable and considerably lower than for most well-known bottlenose dolphin communities. Groups averaged seven individuals, with a mode of two. Groups entirely composed of adults were the smallest, groups with calves the largest. Group fluidity was high, seasonal and yearly changes in mean group size being also considerable. Summer was the peak calving season, with a striking variation in the number of births on alternate years. Poor evidence of shark predation was found. The social organization of this dolphin community seemed to be highly flexible, possibly as an adaptation to cope with environmental changes as well as with a limited and variable availability of prey.     

COMPARATIVE FEEDING ECOLOGY OF SPINNER DOLPHINS (STENELLA LONGIROSTRIS) AND FRASER'S DOLPHINS (LAGENODELPHIS HOSEI) IN THE SULU SEA

Fraser's and spinner dolphins are known to feed on mesopelagic prey, bur their diets and feeding ecologies have not been compared in areas where they are observed together. In this study we examined the stomach contents of both species caught incidentally in a driftnet fishery for tuna in the eastern Sulu Sea. Importance of prey items was determined using the percent occurrence, percent number, and volumetric methods. Mesopelagic fishes, particularly myctophids (mainly Ceratoscopelus warmingi, Diaphus spp. and Myctophum asperum ), were the most important component in the diet of spinner dolphins, whereas in Eraser's dolphins, mesopelagic cephalopods ( Abraliopsis, Onychoteuthis, Histioteuthis , and Chiroteuthis ), and crustaceans ( Notostomos elegans, Acanthephyra quadrispinosa , and Acanthephyra carinata ) appeared to be equally important as the myctophid species. Fraser's dolphins appeared to feed preferentially on larger prey and had more diversified prey (Shannon's diversity index = 1.2) than spinner dolphins (diversity index = 0.9). Vertical distributions of the prey items summarized from published literature indicate that spinner dolphins forage in the upper 200 m and probably occasionally to as deep as 400 m, whereas Fraser's dolphins have a wider vertical foraging range, from near the surface to probably as deep as 600 m.     

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.     

Striped dolphins and short‐beaked common dolphins in the Gulf of Corinth,Greece: Abundance estimates from dorsal fin photographs

Capture‐recapture methods relying on dorsal fin natural markings have never been applied successfully to striped dolphins, Stenella coeruleoalba, and were rarely used to assess abundance of short‐beaked common dolphins, Delphinus delphis. We used digital photo‐identification to obtain abundance estimates of striped and common dolphins living in mixed groups in the Gulf of Corinth, Greece. The proportion of either species was calculated based on the relative number of photographs of adult animals showing relevant portions of their body during conspicuous surfacings. Striped dolphins and common dolphins averaged 95.0% and 3.2% of all individuals, respectively. Animals showing intermediate pigmentation accounted for another 1.8%. Striped dolphin numbers were relatively high, with a point estimate of 835 animals (95% CI = 631–1,106). Common dolphins numbers were low (point estimate 28 animals; 95% CI = 11–73) and individuals were scattered within striped dolphin groups, indicating that this common dolphin population may be nonviable. Within a semiclosed Gulf exposed to considerable anthropogenic impact, the future of both dolphin species is of concern due to their suspected geographic isolation and restricted extent of occurrence. Information provided here can be used to inform timely conservation efforts.     

CETACEANS OF THE WESTERN TROPICAL INDIAN OCEAN: DISTRIBUTION, RELATIVE ABUNDANCE, AND COMPARISONS WITH CETACEAN COMMUNITIES OF TWO OTHER TROPICAL ECOSYSTEMS

We conducted a cetacean survey in the pelagic western tropical Indian Ocean (WTIO) aboard an 85-m research vessel from March to July 1995, covering 9,784 linear km. Using 25 × binoculars and line-transect methods, we recorded 589 sightings of 21 species. Stenella longirostris was the most abundant cetacean, in terms of number of individuals sighted, by an order of magnitude above any other species, while Physeter macrocephalus was the most frequently sighted, in terms of number of schools. Twelve species were widespread, seven were rare, and two were localized; our sightings include new distributional records for 12 species. Significant observations included the following: (1) Delphinus cf. tropicalis was abundant off the coast of Oman (16 sightings) and readily distinguishable in the field from D. delphis and D. capensis, (2) Balaenoptera musculus was fairly common and localized in the area of the Maldives (17 sightings), and (3) three sightings were made of an unidentified bottlenose whale tentatively referred to as Indopacetus (i. e., Mesoplodon) pacificus. We recorded 26 mixed-species cetacean schools, 43 schools with which seabirds associated, and 17 schools associated with tuna. Notable among these were mixed aggregations of Stenella attenuata, S. longirostris, yellowfin tuna, and seabirds. The cetacean community of the WTIO was similar to that of the eastern tropical Pacific (ETP) and the Gulf of Mexico (GM) in several respects. First, differences in abundance rank of individual species were small, with the result that common species were common and rare species were rare, regardless of ocean. Second, these differences in abundance were due primarily to differences in encounter rate, which varied with ocean by as much as 3,000%, and less so to school size, which generally varied less than 100%. Third, regardless of ocean, three species comprised the majority of cetaceans in the community, Stenella attenuata, S. longirostris, and S. coeruleoalba, representing 62%-82% of all individuals for all species. However, the rank order of abundance for these three species differed with ocean. Most notably, S. attenuata was abundant in the ETP and GM (abundance rank = 2 and 1, respectively) but much less common in the WTIO (abundance rank = 6). Although habitat preferences for S. attenuata appear to overlap considerably with those of S. longirostris in the ETP, our results suggest there may actually be significant differences between these two species. Detailed analysis of oceanographic correlates of distribution will be necessary in order to understand fully the habitat requirements of these pelagic dolphins, often the most conspicuous elements of tropical cetacean communities around the world.     

东海水域瓶鼻海豚种群数量和分布的初步研究

运用截线抽样法调查了北纬２５°～３０°,东经１２５°以西的东海水域中瓶鼻海豚在夏季７～９月间的种群密度和数量,得出的最小估计值分别为０．１４００头／ｋｍ２和９９４０头。瓶鼻海豚在该水域的分布特点为：随纬度增加（由南向北）密度逐渐减少,而在经度方向上则没有明显的密度变化规律。     

FIRST RECORD OF GRACILARIA VERMICULOPHYLLA (GRACILARIALES,RHODOPHYTA) IN THE PO DELTA LAGOONS,MEDITERRANEAN SEA (ITALY)1

Molecular outcomes led us to report the first occurrence of the invasive alien species Gracilaria vermiculophylla (Ohmi) Papenf. in the Mediterranean Sea. This species was recorded for the first time in the Po Delta lagoons in May and October 2008, probably introduced by the importation of the Manila clam Tapes philippinarum. At present, G. vermiculophylla is spread only near some clam‐farming areas, but its diffusion is expected to increase with the colonization of other lagoons where aquaculture is spread, as already observed for other alien species such as Agardhiella subulata and Solieria filiformis. The present study supplies further information on the morphology of this species, the ecological characteristics of the colonized areas, and the most probable introduction vector, confirming that the species spreading occurs in eutrophic and turbid coastal systems.     

POPULATION SIZE, DISTRIBUTION, AND BEHAVIOR OF INDO-PACIFIC BOTTLENOSE (TURSIOPS ADUNCUS) AND HUMPBACK (SOUSA CHINENSIS) DOLPHINS OFF THE SOUTH COAST OF ZANZIBAR

Indo-Pacific bottlenose ( Tursiops aduncus ) and humpback dolphins ( Sousa chinensis ) off the south coast of Zanzibar, East Africa, have been subject to both direct and indirect takes as well as disturbance from local dolphin tourism during the last decade. Meanwhile, little or no information on population parameters exists for these animals. In order to assess the anthropogenic threats, a study was conducted between 1999 and 2002 to determine population sizes, distribution, and behavior of these animals. Population sizes were calculated for each year using mark-recapture methods applied to photo-identification data. The estimates ranged between 136 and 179 for the bottlenose dolphins and between 58 and 65 for the humpback dolphins in the calculated 26 km² study area. Patterns in distribution and behavior were investigated using image and spatial statistic software on data from boat surveys. Analyses of spatial densities showed that both species concentrated their activities to smaller areas (2%–11.5%) within the study area. When the study results were considered in light of the anthropogenic threats, it was clear that immediate conservation measures were needed. This is critical if the negative impact on the species is to be minimized and the dolphins are to continue to represent a socioeconomic resource in the region.     

南海断面春季放射虫残骸的空间分布及其与表层沉积记录对比

放射虫是揭示古海洋环境信息的重要载体。本文采用虎红染色方法,首次揭示了南海典型断面现代放射虫残骸群的空间分布特征,并比较分析现代水体中放射虫残骸群与海底表层沉积物中放射虫化石群的相互关系。结果表明:南海春季放射虫残骸群比较丰富,其丰度一般呈现出随深度增加而增高的趋势,最高值主要出现在75—300m深即位于叶绿素最大值层和活体高峰深度之下;分析发现研究区放射虫残骸丰度的深度分布受到海流的横向输运影响;春季水体和表层沉积物中放射虫属种组成和丰度分布的差异表明,除了现代放射虫具有季节性变化之外,海流的横向传输也是一个很重要的原因。在150—300m水体中除了Cornutella profunda和Cyrtopera laguncula,还发现了Cycladophora davisiana的残骸,推测典型冷水种C.davisiana由于受到径向翻转流的作用,从中深层水被带到了中上层水体中。     

RANGE CHARACTERISTICS OF PACIFIC COAST BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) IN THE SOUTHERN CALIFORNIA BIGHT

Boat-based photoidentification surveys of bottlenose dolphins (Tursiops truncatus) were conducted from 1982 to 1989 in three discrete coastal study areas within the Southern California Bight: (1) Santa Barbara, California; (2) Orange County, California; (3) Ensenada, Baja California, Mexico. A total of 207 recognizable dolphins were identified in these three “secondary” study areas. These individuals were compared to 404 dolphins identified from 1981 to 1989 in our “primary” study area, San Diego, California, to examine the coastal movement patterns of bottlenose dolphins within the Southern California Bight. A high proportion of dolphins photographed in Santa Barbara (88%), Orange County (92%), and Ensenada (88%) were also photographed in San Diego. Fifty-eight percent (n= 120) of these 207 dolphins exhibited back-and-forth movements between study areas, with no evidence of site fidelity to any particular region. Minimum range estimates were 50 and 470 km. Minimum travel-speed estimates were 11-47 km/d, and all dolphin schools sighted during the study were within 1 km of the shore. These data suggest that bottlenose dolphins within the Southern California Bight are highly mobile within a relatively narrow coastal zone. Home-range dimensions and movement patterns for many vettebrate species are influenced, in part, by variation in food resources. The unique range characteristics documented during this study may reflect the highly dynamic nature of this coastal ecosystem and the associated patchy distribution of food resources available to these bottlenose dolphins.