AGE STRUCTURE AND GROWTH OF THE BOTTLENOSE DOLPHIN (TURSIOPS TRUNCATUS) FROM STRANDINGS IN THE MISSISSIPPI SOUND REGION OF THE NORTH-CENTRAL GULF OF MEXICO FROM 1986 TO 2003

Despite their high abundance and wide distribution, little is known about the historical or current growth and age structure of coastal bottlenose dolphins ( Tursiops truncatus ) in the north-central Gulf of Mexico. Between 1986 and 2003, teeth were collected from bottlenose dolphins stranded on the mainland coast of Mississippi and the adjacent barrier islands. Bottlenose dolphin strandings occurred year round, peaking in March and April. Neonate strandings also peaked during these 2 mo. Age estimates were obtained from 111 animals by reading the growth layer groups in the dentine layer of the teeth. The ages ranged from <1 yr to 30 yr of age. The two-stage Laird–Gompertz growth model was fitted to the total length and age data. On the basis of this model, the asymptotic lengths were estimated at 250 cm for females and 255 cm for males. The length at birth estimates were 98–103 cm for females and 100–107 cm for males. These lengths are similar to those of bottlenose dolphin populations from other Gulf of Mexico areas and from the North Atlantic Ocean along the southeastern United States.     

PHYSICAL HABITAT OF CETACEANS ALONG THE CONTINENTAL SLOPE IN THE NORTHCENTRAL AND WESTERN GULF OF MEXICO

The physical habitat of cetaceans found along the continental slope in the north-central and western Gulf of Mexico was characterized from shipboard sighting data, simultaneous hydrographic measurements, and satellite remote sensing. The study area was encompassed by the longitude of the Florida-Alabama border (87.5°W), the southernmost latitude of the Texas-Mexico border (26.0°N), and the 100-m and 2,000-m isobaths. Shipboard surveys were conducted seasonally for two years from April 1992 to May 1994. A total of 21,350 km of transect was visually sampled in an area of 154,621 km². Sighting localities of species in the study area were differentiated most clearly with bottom depth. Atlantic spotted dolphins (Stenella frontalis) were consistently found in the shallowest water on the continental shelf and along the shelf break. In addition, the bottom depth gradient (sea floor slope) was less for Atlantic spotted dolphins than for any other species. Bottlenose dolphins (Tursiops truncatus) were found most commonly along the upper slope in water significantly deeper than that for Atlantic spotted dolphins. All the other species and species categories were found over deeper bottom depths; these were Risso's dolphins (Grampus griseus), short-finned pilot whales (Glob-icephala macrorhynchus), pygmy/dwarf sperm whales (Kogia spp.), roughtoothed dolphins (Steno bredanensis), spinner dolphins (Stenella longirostris), sperm whales (Physeter macrocephalus), striped dolphins (Stenella coeruleoalba), Mesoplodon spp., pantropical spotted dolphins (Stenella attenuata), Clymene dolphins (Stenella clymene) and unidentified beaked whales (Ziphiidae). Risso's dolphins and short-finned pilot whales occurred along the upper slope and, as a subgroup, were significantly different from striped dolphins, Mesoplodon spp., pantropical spotted dolphins, Clymene dolphins, and unidentified beaked whales, which occurred in the deepest water. Pygmy/dwarf sperm whales, rough-toothed dolphins, spinner dolphins, and sperm whales occurred at intermediate depths between these two subgroups and overlapped them.     

HABITAT USE PATTERNS AND RANGES OF THE BOTTLENOSE DOLPHIN IN THE GULF OF CALIFORNIA, MEXICO

Abstract: I studied behavior and range patterns of individual bottlenose dolphins during 1984 in the mid-eastern Gulf of California, Mexico. Dolphin sighting rate was significantly higher in areas close to estuary mouths, 0.306 sightings per hour compared with 0.155 sightings per hour in areas distant from estuary mouths. Dolphins used these estuarine areas to feed; 61% of all behavior observed near estuaries was feeding as compared with 23% elsewhere. Traveling comprised 61% of all behavior observed in areas distant from estuary mouths. Estuaries are sites of large concentrations of nutrients which support great numbers of filter-feeding zooplankton and fish. Bottlenose dolphins may specialize on esmarine prey, or they may feed in estuarine areas simply because of the abundance of potential prey that these systems support. In either case, data on relative numbers, distribution patterns, behavior and diet indicate that this is a general trend in habitat use for many coastal populations of this species in the Pacific and Atlantic.
Ranges of a few individuals spanned a minimum of 65 km of coastline, and animals were not permanent residents of a monitored bay. In contrast, dolphins off the coast of Sarasota, Florida, have been reported to be year-round residents with smaller ranges. This difference in degree of site fidelity may be related to habitat differences. The west coast of Florida is dotted with numerous and large estuarine systems which may host permanent prey populations and support resident groups of dolphins. The Gulf of California coastline contains few estuaries; most are small and perhaps support prey resources which are ephemeral, requiring dolphins to range over larger distances in search of food.     

ABUNDANCE OF CETACEANS IN THE OCEANIC NORTHERN GULF OF MEXICO, 1996–2001

The Gulf of Mexico is a subtropical marginal sea of the western North Atlantic Ocean with a diverse cetacean community. Ship-based, line-transect abundance surveys were conducted in oceanic waters (>200 m deep) of the northern Gulf within U. S. waters (380,432 km²) during spring from 1996 to 1997 and from 1999 to 2001. Data from these five surveys were pooled and minimum abundance estimates were based on 12,162 km of effort and 512 sightings of at least 19 species. The most commonly sighted species (number of groups) were pantropical spotted dolphin, Stenella attenuata (164); sperm whale, Physeter macrocephalus (67); dwarf/pygmy sperm whale, Kogia simalbreviceps (58); Risso's dolphin, Grampus griseus (38); and bottlenose dolphin, Tursiops truncatus (24). The most abundant species (number of individuals; coefficient of variation) were S. attenuata (91,321; 0.16); Clymene dolphin, S. clymene (17,355; 0.65); spinner dolphin, S. longirostris (11,971; 0.71); and striped dolphin, S. coeruleoalba (6,505; 0.43). The only large whales sighted were P. macrocephalus (1,349; 0.23) and Bryde's whale, Balaenopteraedeni (40; 0.61). Abundances for other species or genera ranged from 95 to 2,388 animals. Cetaceans were sighted throughout the oceanic northern Gulf and, whereas many species were widely distributed, some had more regional distributions.     

A DWARF FORM OF THE SPINNER DOLPHIN (STENELLA LONGIROSTRIS) FROM THAILAND

A very small form of the spinner dolphin has been found to inhabit the Gulf of Thailand. Ten specimens taken incidentally in a local shrimp fishery differ from specimens of this species collected elsewhere in body size and shape, skull size and shape, number of teeth and numbers of thoracic and lumbar vertebrae. Four cranially adult males were 129–137 cm long, well below the ranges for the Indian Ocean, western Pacific, central Pacific, eastern Pacific and Atlantic. The skull is also very small. Tooth counts and vertebral counts average lower than in other series. The color pattern is not significantly different from that of spinner dolphins in the central and western Pacific, Atlantic and Indian Oceans but differs from that of the small eastern spinner of the eastern Pacific. The Gulf of Thailand specimens are morphologically separable from all other specimens, but it is to be expected that when larger samples are available there will be some overlap. The dwarf form may overlap in body and skull size with small spinner dolphins taken incidentally in a gillnet fishery for sharks off northern Australia. The geographic range of the dwarf spinner may be restricted. The size and status of the population and the impact of the shrimp fishery are unknown and should be investigated. The dwarf spinner may have an ecology different from that of other spinners, feeding mainly on reef-associated and benthic organisms rather than mesopelagic animals.     

PHYLOGENETIC ANALYSIS OF BRACHIDINIUM CAPITATUM (DINOPHYCEAE) FROM THE GULF OF MEXICO INDICATES MEMBERSHIP IN THE KARENIACEAE1

Brachidinium capitatum F. J. R. Taylor, typically considered a rare oceanic dinoflagellate, and one which has not been cultured, was observed at elevated abundances (up to 65 cells · mL^?1) at a coastal station in the western Gulf of Mexico in the fall of 2007. Continuous data from the Imaging FlowCytobot (IFCB) provided cell images that documented the bloom during 3 weeks in early November. Guided by IFCB observations, field collection permitted phylogenetic analysis and evaluation of the relationship between Brachidinium and Karenia. Sequences from SSU, LSU, internal transcribed spacer (ITS), and cox1 regions for B. capitatum were compared with five other species of Karenia; all B. capitatum sequences were unique but supported its placement within the Kareniaceae. From a total of 71,487 images, data on the timing and frequency of dividing cells was also obtained for B. capitatum, allowing the rate of division for B. capitatum to be estimated. The maximum daily growth rate estimate was 0.22 d^?1. Images showed a range in morphological variability, with the position of the four major processes highly variable. The combination of morphological features similar to the genus Karenia and a phylogenetic analysis placing B. capitatum in the Karenia clade leads us to propose moving the genus Brachidinium into the Kareniaceae. However, the lack of agreement among individual gene phylogenies suggests that the inclusion of different genes and more members of the genus Karenia are necessary before a final determination regarding the validity of the genus Brachidinium can be made.     

CETACEANS OF THE NORTHERN GULF OF CALIFORNIA: DISTRIBUTION, OCCURRENCE, and RELATIVE ABUNDANCE

A total of 1,715 km of boat-based surveys and 1,521 km of aircraft-based surveys was conducted from 1986–1989 to assess the distribution, relative abundance, and ecological relationships of cetaceans in the northern Gulf of California. Seven cetacean species were seen; in decreasing frequency of groups encountered they were: bottlenose dolphins, Tursiops truncatus ; vaquitas, Phocoena sinus ; common dolphins, Delphinus delphis ; fin whales, Balaenoptera physalus ; Bryde's whales, B. edeni ; gray whales, Eschrichtius robustus , and killer whales, Orcinus orca. Common dolphins were numerically dominant and bottlenose dolphins were seen most often. Bryde's whales and vaquitas had the smallest group sizes. In general, the odontocete cetaceans were separated spatially, whereas the distribution of Bryde's and fin whales overlapped considerably.     

中国南海北部北部湾水母类调查及三新种记述(刺胞动物门)(英文)

材料系于2007年(1,4,7,10月)、2008年(1,7月)和2009年(1月)在北部湾水域采集的,调查海区共设52站,共采集364份样品。经分析鉴定出67种水母,其中有3新种和中国2新纪录,主辐特古水母Tregouboiva perradialis Xu,Huang et Du,sp. nov.,泡真囊水母Euphysora vacuola Xu,Huang et Guo,sp. nov.,波腺侧丝水母Helgicirrha sinuatus Xu,Huang et Du,sp. nov.,艾格帝纹水母Timoides agassizi Bigelow,1904和大腺美螅水母Clytia macrogonia Bouillon,1984。此外,还报道了20种水母为北部湾新纪录。模式标本保存在中国水产科学研究院南海水产研究所。主辐特古水母,新种Tregoubovia perradialis Xu,Huang et Du,sp. nov.鉴别特征伞近钟形,外伞有16条双层向心肋; 垂管很大,近方形,约为内伞腔深度4/5;口有4个延长成触手状的口唇,具环状刺胞,无末端刺胞球;隔膜短;4个大的椭圆形生殖腺,几乎覆盖整个垂管主辐位;伞缘无缘触手或缘基球;无眼点。正模(BG 001),北部湾S30站(17°30’N,107°30’E;水深70m),2008-07-06,梁新采(南海水产研究所)。词源:新种种名源自拉丁词perradialis,意为生殖腺位于垂管主辐位。泡真囊水母,新种Euphysora vacuola Xu,Huang et Guo,sp. nov.鉴别特征伞有钝圆形顶突;垂管长椭圆形,约有1/2长度超出缘膜口外,垂管基部很宽,覆盖着浓密泡状细胞组织;4条辐管上部与扩大的垂管基部连接;生殖腺围绕着垂管壁;主触手很长,触手基球很大,呈卵圆形至球形,触手上具30～40个成排的背轴刺胞球,无末端膨大刺胞球,另3个触手基球退化,很小,同样大小,无丝状触手,每个基球具外胚层背距。正模(BG 006),北部湾C15站(20°N,109°E;水深44m),2007-07-25,梁新采(南海水产研究所)。副模(TB001),台湾海峡102站(23°40’N,118°44’E;水深54m),1988-06-29,黄加祺采(厦门大学海洋学系)。词源:新种种名源自拉丁词vacuola,意为该种在垂管基部覆盖浓密泡状细胞组织。波腺侧丝水母,新种 Helgicirrha sinuatus Xu,Huang et Du,sp.nov.鉴别特征伞略扁于半球形;胃柄长,约有1/2超出缘膜口外,垂管短小,口有4个短的略为向上弯曲折叠的口唇;生殖腺深波形,位于辐管远端1/3处; 16 ～ 24 条缘触手,每条触手具2对侧丝,每2条触手间有3～5个缘疣,具1对侧丝和3～4个平衡囊,每个平衡囊有2～4个平衡石;所有触手和缘疣基部均有向轴排泄乳突。正模(BG 007),副模(BG 008-009),北部湾S18站( 18°45’N,106°45’E;水深53m),2007-04-15,梁新采(南海水产研究所)。词源:新种种名源自拉丁词sinuatus,意为该种生殖腺深波状。     

DOES ELASTIN CONTRIBUTE TO THE PERSISTENCE OF CORPORA ALBICANTIA IN THE OVARY OF THE COMMON DOLPHIN (DELPHINUS DELPHIS)

The corpora albicantia (CAs) from the ovaries of 39 common dolphins ( Delphinus delphis ) caught in driving fisheries were used, and histologically and immunohistochemically examined. The area of each corpus albicans (CA) and the proportion of that area occupied by elastin were measured using NIH-image software. In all CAs, elastoid material (EM) was apparent although EM area varied in each CA. CAs increased in number with dolphin age. Smaller CAs contained a higher proportion of EM. EM was completely digested by elastase, but not by collagenase. Furthermore, EM was immunostained with anti-α-elastin antibody. These results demonstrated that EM was elastin. The present study is the first to describe the presence of elastin in cetacean CAs. The higher proportion of elastin in small-sized CAs of common dolphins is suggested as the likely cause of the persistence of CA.     

CROSS-REACTIVITY OF ANTIBODIES TO HUMAN ANTIGENS WITH TISSUES OF THE BOTTLENOSE DOLPHIN, TURSIOPS TRUNCATUS, USING IMMUNOPEROXIDASE TECHNIQUES

Cross-species reactivity of 53 antibodies developed against human antigens was evaluated in the bottlenose dolphin Tursiops truncatus , using immunoperoxidase techniques, Strong cross-reactivity was demonstrated with antibodies against intermediate filaments, most hormones, but few leukocyte antigens. S100, NSE, F8RA, Factor XIIIa, and lactalbumin antibodies reacted, while HMB45, EMA, PLAP, and PSA did not. Polyclonal antibodies are much more likely to cross-react than are monoclonal antibodies. Twenty-four of 30 (80%) of polyclonals cross-reacted, while only 10 of 23 (43.5%) monoclonals cross-reacted. Some antigens are demonstrated only after using a special technique to unmask the antigen.     

BEHAVIOR AND ECOLOGY OF THE ATLANTIC WHITE-SIDED DOLPHIN (LAGENORHYNCHUS ACUTUS) IN COASTAL NEW ENGLAND WATERS

Atlantic white-sided dolphins ( Lagenorhynchus acutus ) are among the most abundant, and least studied, cetaceans in coastal New England. Between April and October 1984 through 1997 we sighted 1,231 groups of Atlantic white-sided dolphins, primarily on Stellwagen Bank and Jeffreys Ledge (two shallow glacial deposits along the coasts of Massachusetts, New Hampshire, and Maine). Mean group size was 52 (≥90.9), and was significantly larger from August through October (71.9 ± 111.4) than April through June (35.0 ± 45.4). Calf sightings were uncommon until June and July, after which they were present in over 50% of groups. Combined with observations of apparent newborn calves, this confirms that early summer is an important calving period. The presence of calves did not, however, solely account for the increase in group size. Boat interaction (bow- and stern-wake riding) was the most commonly recorded behavior (47.4% of sightings), followed by traveling (31.4%), interactions with other cetacean species (27.6%), social interaction (15.5%), and feeding (9.5%). While feeding was uncommon, one observation of apparently coordinated "ball" feeding was seen with sand lance ( Ammodytes spp.) as the visible prey. Aerial behavior showed a positive correlation with group size, although it was often impossible to tell whether the same dolphins were leaping repeatedly. Eighty-eight dolphins were photo-identified using either unusual body pigment or a distinctive dorsal fin. While several individuals were reidentified between years and between areas, no reidentifications were made within a year in the same area. Unusually pigmented individuals were much more likely to be reidentified than those with distinctive dorsal fins, most likely due to higher visibility. We suggest that Atlantic white-sided dolphins are generally using the study area as transients in what appears to be a large home range.     

POPULATION DYNAMICS OF GREEN NOCTILUCA SCINTILLANS (DINOPHYCEAE) ASSOCIATED WITH THE MONSOON CYCLE IN THE UPPER GULF OF THAILAND1

Population dynamics of Noctiluca scintillans (Macartney) Kof. et Swezy containing the photosynthetic endosymbiont Pedinomonas noctilucae (Subrahman.) Sweeney was investigated in relation to environmental conditions in the upper Gulf of Thailand. A clear association was observed between the abundance of N. scintillans and the monsoon cycle, with its blooms occurring during the southwest (SW) monsoon from May to September, and low abundance during the northeast (NE) monsoon from November to February. Nutrient concentrations were higher during the SW monsoon than during the NE monsoon due to the combined effect of increased river discharge into the northern upper gulf and the transport of the riverine inputs by the prevailing clockwise circulation of the water. These nutrient conditions favored the growth of both phytoplankton and the endosymbiont. Correlation analysis revealed that the higher abundance of N. scintillans in the SW monsoon was manifested primarily by higher growth through both sexual and asexual reproduction supported by phagotrophy. However, the dependence of N. scintillans on the nutrient concentration was not significant, probably because the nutrient supply for the endosymbiont was sufficient due to intracellular accumulation of nutrients within the host cells. Sexual reproduction occurred only during the SW monsoon, and its potential importance in population growth was suggested. These findings showed the bottom‐up control of the population dynamics of N. scintillans through growth of phytoplankton as prey. The seasonal shift in the circulation pattern associated with the monsoon cycle played a crucial role in blooming of N. scintillans by producing favorable food conditions.     

DESCRIPTION OF A NEW DOLPHIN, THE AUSTRALIAN SNUBFIN DOLPHIN ORCAELLA HEINSOHNI SP. N. (CETACEA, DELPHINIDAE)

Comparisons of the Irrawaddy dolphin, Orcaella brevirostris , between Australian and Asian sites documented geographic differences in height of dorsal fin, presence or absence of a median dorsal groove in front of the dorsal fin, and coloration (presence or absence of a dorsal cape). Analysis of genetic data provided support for two clades within the Asian samples, the Mekong River samples from Cambodia and southern Laos, and all other marine and freshwater sites from Thailand, Indonesia, and the Philippines. The major separation, however, was between sites in Asia and those from Australia (5.9% of base pair differences, compared with 1.2% for within Australia and 1.5% for within Asia). Within a 403 base segment of the mtDNA control region, Australian specimens had 17 diagnostic sites with 16 fixed base pair differences and one insertion/deletion. Consistent, statistically significant differences in skull characters of Australian specimens have previously been demonstrated and are reviewed in this paper. There was a high concordance in character differences demonstrated between O. brevirostris from all Asian sites and Australian specimens, especially in the genetic and osteological characters. Based on the range and concordance of character differences, we propose that the Australian dolphins be recognized as a new species, Orcaella heinsohni (suggested common name: Australian snubfin dolphin).     

THE TROPHIC ROLE OF MARINE MAMMALS IN THE NORTHERN GULF OF ST. LAWRENCE

The trophic role of apex predators was evaluated in the northern Gulf of St. Lawrence ecosystem. An Ecopath model was developed for the period 1985–1987 prior to the collapse of commercially exploited demersal fish stocks in this area. Marine mammal trophic levels were estimated by the model at 4.1 for cetaceans, 4.4 for harp seals (Pagophilus groenlandicus), 4.7 for hooded seals (Cystophora cristata), 4.5 for gray seals (Halichoerus grypus), and 4.3 for harbor seals (Phoca vitulina). Harp seals were the third most important predator on vertebrate prey following large Atlantic cod (Gadus morhua) and redfish (Sebastes spp.). Different seal species preyed on different levels of the food chain. Harp seals preyed on most trophic groups, whereas larger seals, such as gray seals and hooded seals, mainly consumed higher trophic levels. The model suggested that apex predators had a negative effect on their dominant prey, the higher trophic level fish, but an indirect positive feedback on the prey of their preferred prey, mainly American plaice (Hippoglossoides platessoides), flounders, skates, and benthic invertebrates. Our results suggest that both marine mammals and fisheries had an impact on the trophic structure.     

白暨豚腐皮病致病细菌的初步研究

对白鱀豚腐皮病致病细菌的分离、培养、毒力试验和详细的生理生化测定,初步确定Ⅰ型荧光极毛杆菌为其病原菌。又对该细菌进行了药物抑菌试验,筛选出几种较为有效的药物。     

VARIATIONS OF PSP TOXIN PROFILES DURING DIFFERENT GROWTH PHASES IN GYMNODINIUM CATENATUM (DINOPHYCEAE) STRAINS ISOLATED FROM THREE LOCATIONS IN THE GULF OF CALIFORNIA,MEXICO1

In vitro experiments were performed with Gymnodinium catenatum Graham strains isolated from three locations in the Gulf of California to determine the variability in toxicity and toxin profiles. Strains were cultivated in GSe at 20°C±1°C, 150 μmol photons·m^?2·s^?1 (12:12 light:dark cycle), and harvested during different growth phases. Growth rates were higher than in previous studies, varying between 0.70 and 0.82 day^?1. The highest cell yields were reached at 16 and 19 days, with maximum densities between 1090 and 3393 cells·mL^?1. Bahía de La Paz (BAPAZ) and Bahía de Mazatlán (BAMAZ) were the most toxic (101 pg STXeq·cell^?1), whereas strains from Bahía Concepción (BACO) were the least toxic (13 pg STXeq·cell^?1). A strain isolated from cyst germination was one of the least toxic strains. No significant changes in toxin content with culture age were observed (0.2 and 0.6 pmol paralytic shellfish poisoning·cell^?1). All strains contained neosaxitoxin (NEOSTX), decarbamoyl‐saxitoxin (dcSTX), decarbamoyl‐gonyautoxin‐2,‐3, (dcGTX2‐3), N‐sulfo‐carbamoylsaxitoxin (B1), N‐sulfo‐carbamoylneosaxitoxin (B2), and N‐sulfo‐carbamoylgonyautoxin‐2,‐3 (C1‐2). Bahía Concepción strains had the highest content of C1; BAPAZ and BAMAZ strains had a higher percentage of NEOSTX. Differences in toxin composition with culture age were observed only in BAMAZ and BAPAZ strains. Cultures with a higher percentage of long chains had more NEOSTX, while those with a higher proportion of short chains had a lower content of NEOSTX. Gulf of California strains are characterized by a high proportion of NEOSTX, and seem to have evolved particular physiological responses to their environment that are reflected in the toxin profile, suggesting different populations.