CRANIAL SEXUAL DIMORPHISM AND GEOGRAPHIC VARIATION IN ERASER'S DOLPHIN, LAGENODELPHIS HOSEI

Knowledge of geographic variation is important to questions of population assessment and management. Fraser's dolphins have been exploited in two regions in the western Pacific. Analysis of 137 skulls from the Philippines, Japan, Taiwan, Australia, Indonesia, Malaysia, South Africa, France, the U.S., St. Vincent and the Grenadines, and the eastern tropical Pacific revealed sexual dimorphism in 5 of 26 measurements (difference of 1.9%-5.8% between males and females), similar to levels of cranial dimorphism in other small pelagic delphinids. Males had a larger braincase and temporal fossae and smaller external nares than females. Sexually dimorphic characters were excluded, and male and females samples were pooled to examine geographic differences in the remaining characters. Multivariate analyses yielded significant differences between the Philippine and Japanese series within the North Pacific and between a pooled North Pacific series and a North Atlantic series. The Japanese skulls were on average broader and had a wider rostrum, larger orbit, larger internal nares, and longer braincase than the Philippine skulls. These differences suggest that Fraser's dolphins exploited in Japanese and Philippine waters in directed fisheries or as by catch belong to different populations and should be assessed and managed separately.     

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.     

OBSERVATIONS ON THE LIFE HISTORY OF PAPENFUSSIELLA CALLITRICHA (PHAEOPHYCEAE,CHORDARIALES) IN CULTURE1

Papenfussiella callitricha (Rosenv.) Kylin from eastern Canada was studied in culture. Zoids from unilocular sporangia develop into microscopic, filamentous, dioecious gametophytes which produce isogametes in filament cells and few-chambered plurilocular gametangia. Unfused gametes germinate to reproduce the gametophytes. Fusion takes place between a settled (“female”) and a motile (“male”) gamete. The zygote gives rise to a filamentous plethysmothallus that reproduces asexually by zoids formed in thallus cells and in few-chambered plurilocular zoidangia. Erect macrothalli are produced on the plethysmothallus, beginning with the formation of upright filaments. Later on, these filaments become the terminal assimilators of the macrothalli. Further assimilatory filaments, rhizoids, and unilocular sporangia are produced in a branching region at the base of the terminal assimilator. Zoids from unilocular sporangia formed in culture germinate to reestablish the gametophyte phase. Chromosome counts yielded n = 19 ± 3 for the gametophytes, and 32 ± 6 for the sporophyte, both plethysmothallus and macrothallus.     

THE LIFE HISTORY OF FREE-RANGING ATLANTIC SPOTTED DOLPHINS (STENELLA FRONTALIS): AGE CLASSES, COLOR PHASES, AND FEMALE REPRODUCTION

Atlantic spotted dolphins (Stenella frontalis) were observed underwater and from the surface from 1985 to 1996 and photographed through successive years. Individuals were categorized into age classes by their degree of spotting and color phases. Dolphins spent an average of 3 yr in the two-tone color phase, 5 yr in the speckled phase, 7 yr in the mottled phase and up to 10 yr or more in the fused phase.
Sex ratios were close to parity, with old adults skewed towards females and juveniles and young adults skewed towards males. The average calving interval for 24 females was 2.96 years with a range of 1–5 yr. Females whose calves survived the first year had a significantly longer calving interval (3.56 years). The ages of first parturition for five females were estimated to be 10–12 yr. The age at sexual maturation was estimated to range from 8 to 15 yr.
Pregnancy rate fluctuated annually, with an average rate of 0.25 (range 0.07–0.57). Annual average birth rate was 0.08 (range 0.07–0.14), average calf production was 0.33 (range 0.06–0.52), average fecundity was 0.23 (range 0.13–0.30), and average recruitment was 0.06 (range 0.03–0.08). Most females who lost a calf conceived the same or following year.
Lactation lasted up to 5 yr, and 45% of visibly pregnant females were also lactating. Age of first parturition was associated with the mottled color phase. Average first-year mortality rate of calves was 0.24.     

REPRODUCTIVE MATURITY AND SEASONALITY OF MALE SPOTTED DOLPHINS, STENELLA ATTENUATA, IN THE EASTERN TROPICAL PACIFIC

We estimated age at attainment of sexual maturity and examined reproductive seasonality for male spotted dolphins, Stenella attenuata , from the eastern tropical Pacific Ocean. Maturity was determined by histological examination of testes. Average age at sexual maturation was 14.7 yr (the mean of two readers' age estimates). Testis and epididymis weight and seminiferous tubule diameters were reliable indicators of maturity, whereas age, length and color phase were less reliable. Seasonality was determined by changes in testis and epididymis weight, relative quantity of spermatids and spermatozoa, and lumen diameter, as well as an index of testis development (weight of the right testis and epididymis divided by length of the right testis). Testis and epididymis weights and index values peaked in July and August, midway between two predicted mating seasons for the northern offshore stock, but spermatozoa levels were elevated during the predicted breeding seasons.     

REPRODUCTION AND LIFE HISTORY OF THE RED ALGA GALAXAURA OBLONGATA (NEMALIALES,GALAXAURACEAE)1

Culture and morphological studies showed that Galaxaura oblongata (Ellis et Solander) Lamouroux has a triphasic life history with conspicuous gametophytes and small filamentous tetrasporophytes. Development of male and female reproductive structures is very similar and both begin with the enlargement of a terminal cell of a filament branch occupying a normal vegetative position within the apical pit of a thallus branch. In male thalli this modified branch forms a conceptacle in which spermatangia are produced. In female thalli, this modified branch forms a three-celled carpogonial branch consisting of a carpogonium, hypogynous cell and basal cell. Filament branches from the basal cell form a pericarp and the gonimoblast develops directly from the carpogonium. Carposporangia are produced in conceptacles which resemble the male conceptacles. About the time the first carposporangia are produced, the carpogonium, hypogynous cell and basal cell form a large fusion cell. Released carpospores germinate in a unipolar or bipolar manner and form small filamentous thalli. Under short day conditions, cruciate tetrasporangia are produced in small clusters. Tetraspores germinate similarly to carpospores and also form small filamentous thalli. Under low nutrient conditions, small cylindrical thalli develop on the filaments and these appear similar to gametophytes collected in nature.     

卵形异绒螨的形态和生活史研究(真螨目：绒螨科)

卵形异绒螨Allothrombium ovatum Zhang et Xin,1992是我国北方地区棉蚜Aphis gossypii Giover,1877的一种外寄生性天敌。通过室内饲养和田间观察结果表明：该螨一年发生一代,以卵在土壤内越冬。在年平均温度13.7℃条件下,其卵、前幼螨、幼螨、若蛹、若螨、成蛹和成螨的发育历期平均为220.8d、19.5d、22.0 d、12.0 d、13.0 d、13.0 d和59.O d。另外,本文还对卵形异绒螨主要虫态的形态和习性进行了描述和研究。     

GROWTH OF BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) FROM THE INDIAN RIVER LAGOON SYSTEM, FLORIDA, U. S. A.

Gompertz growth models were fitted to total lengths and ages from tooth sections of 199 stranded bottlenose dolphins ( Tursiops truncatus ) from the Indian River Lagoon system, eastern Florida. Based on the model, dolphins from this population are estimated to be born at 119 cm and reach asymptotic length at 250 cm. No apparent pubescent growth acceleration was noted for either sex. Males appeared to grow to slightly longer lengths than females. There were small size differences between Indian River dolphins and those in Texas and Sarasota, indicating general size similarities between North Atlantic and Gulf of Mexico bottlenose dolphins stocks.     

A COMPREHENSIVE STUDY OF THE LIFE CYCLE OF A SOUTH AMERICAN POPULATION OF STIGEOCLONIUM TENUE (CHAETOPHORALES,CHLOROPHYTA)1

The diplobiontic–haplodiplontic life cycle with alternating isomorphic generations in Stigeoclonium tenue (C. Agardh) Kütz. is described for the first time. Sporophytes (2n = 10) arise from tetraflagellate zoospores that are produced by meiosis. Sporic meiosis might be inferred from the cruciform divisions formed during zoosporogenesis and is confirmed through observations of prophase I substages. Zoospores do not germinate directly but produce a haploid cyst that germinates to give rise to a gametophyte (n = 5). Gametophytes produce biflagellate isogametes, which fuse to produce zygotes that germinate by mitosis into the sporophytic stage. Gametophytes and sporophytes reproduce asexually both via mitotic tetraflagellate zoospores and by thallus fragmentation. Results from this study indicate that both the cosmopolitan distribution and dominance of S. tenue in many periphytic communities might be due to its multiple reproductive strategies.     

CULTURE STUDIES ON THE RELATIONSHIP BETWEEN SCHIZYMENIA AND HAEMATOCELIS (GIGARTINALES,RHODOPHYCEAE) FROM THE PACIFIC COAST OF NORTH AMERICA1

Carpospores from Schizymenia pacifica (Kylin) Kylin (Gymnophlaeaceae) from California formed crusts anatomically identical to Haematocelis rubens J. Agardh (Cruoriaceae). Tetraspores of H. rubens from Monterey, California, and Baja California, Mexico, germinated to form basal discs from which arose upright multiaxial blades with a filamentous medulla and cortical gland cells. Pro-carps and spermatangia were present on the same blades; subsequently, cystocarps characteristic of Schizymenia pacifica developed. Re-examination of herbarium specimens suggests that the foliose tetrasporangial phases previously reported as S. pacifica are referable to Halymenia, Dilsea, Cryptonemia, or Turnerella. Schizymenia pacifica (type locality: San Juan Islands, Washington) thus is considered to be the gametophyte in the life history of Haematocelis rubens (type locality: Brest, France), which has also been reported to be the tetrasporophyte of S. dubyi (Chauvin ex Duby) J. Agardh (type locality: Cherbourg, France). Atlantic and Pacific gametophytes and tetrasporophytes are anatomically very similar, suggesting that only one species is involved, but critical studies must be made before a decision on this taxonomic question can be reached. Haematocelis zonalis Dawson et Neushul (type locality: Anacapa Island, California) is considered to be a growth form of the tetrasporangial phase of S. pacifica.     

LIFE HISTORIES OF BLIDINGIA MINIMA (CHLOROPHYCEAE), ESPECIALLY SEXUAL REPRODUCTION1

Blidingia minima (Näg. ex Kütz.) Kylin from Muroran, Hokkaido, Japan, has been shown to exhibit four patterns of life history in culture. Sexual reproduction, reported fully for the first time in the genus, occurs in two of them. I. An isomorphic-heteromorphic complex in which erect, tubular sporophytes alternate with dioecious gametophytes of the same forms, with the irregular production by both phases of discoid or pulvinate (pincushion-like) microthalli capable of both sexual and asexual reproduction. II. An alternation of heteromorphic phases in which an erect, tubular sporophyte alternated irregularly with a gametophytic microthallus. III. An asexual alternation of heteromorphic phases in which an erect, tubular frond alternates irregularly with a microthallus by means of quadriflagellate zoospores. IV. An asexual, monophasic life cycle in which erect, tubular fronds are perpetuated by quadriflagellate zoospores. The first pattern occurred in spring populations from one of three sites. The second occurred in populations from two sites. The third and fourth occurred in all populations tested. The life history of Blidingia minima from Muroran is similar to that of Kornmannia zostericola from Muroran.     

ARE LIFE HISTORY CHARACTERISTICS GOOD PREDICTORS OF GENETIC DIVERSITY AND STRUCTURE? A CASE STUDY OF THE INTERTIDAL ALGA FUCUS SPIRALIS (HETEROKONTOPHYTA; PHAEOPHYCEAE)1

Characteristics of an organism's life history are often good predictors of genetic diversity and genetic structure. We tested hypotheses about genetic structure and diversity in an intertidal alga based on life history and life form. Fucus spiralis L. is a perennial monoecious alga that is abundant on the shores of Maine. Reproduction in fucoids is highly sensitive to water motion, resulting in fertilization success close to 100%. Given these life history characteristics, we predicted genetic structure among populations to be high and genetic diversity within populations to be low. We used five microsatellite loci to analyze genetic structure and diversity in F. spiralis from four sites on each of two coastal points, Maine, USA. Observed heterozygosities were relatively low (0.23 to 0.56), and F_IS estimates were usually significantly large, ranging from 0.021 to 0.476. This suggests that selfing and/or inbreeding may occur. Contrary to predictions, genetic differentiation between the two coastal points was insignificant. Moreover, few sites were genetically different from one another. Pairwise tests revealed complex patterns among sites. Genetic differentiation was not correlated with distance (P>0.05). Life history characteristics are good predictors of genetic diversity but not of population genetic structure in F. spiralis. We suggest that long distance dispersal of F. spiralis via drifting algal rafts increases gene flow. In addition, low levels of genetic structure may arise due to episodic recruitment or recent recolonization events. We discuss the implications of our results in terms of using life history characteristics as predictors of genetic diversity and structure in algae.     

AGE,GROWTH, AND REPRODUCTIVE PATTERNS OF DALL'S PORPOISE (PHOCOENOIDES DALLI) IN THE CENTRAL NORTH PACIFIC OCEAN

Life history parameters were estimated for Dall's porpoise, Phocoenoides dalli, from biological specimens collected in the western Aleutian Islands, during 1981–1987. Of 2,033 males and 3,566 females examined, reproductive data were available for 1,941 males and 1,906 females; ages were determined for 813 males and 1,297 females. Female sexual maturity was based on the presence of one or more corpus on either ovary; 845 were sexually immature and 1,061 were sexually mature. Two estimates of female average age at sexual maturity (ASM) were 3.8 and 4.4 yr; average length at sexual maturity (LSM) was 172 cm. Males were considered sexually mature when evidence of spermatogenesis was detected; 1,136 were sexually immature and 805 were sexually mature. Two estimates of male ASM were 4.5 and 5.0 yr; LSM was 179.7 cm. Physical maturity was assessed for 246 males and 446 females by examining the degree of fusion in thoracic vertebral epiphyses. For both sexes, the average age at physical maturity was 7.2 yr. Average length at physical maturity was 202.6 cm for males and 192.7 cm for females. Average lengths of physically mature males (x?= 198.1 cm, SE = 0.8566) and females (x?= 189.7 cm, SE = 0.4002) were significantly different(P < 0.0001). Early postnatal growth was rapid in both sexes. A secondary growth spurt in both mass and length was characteristic for both sexes; the increase in length preceded the mass increase by 1–2 yr. Average length at birth (LOB) was approximately 100 cm; birth mass averaged 11.3 kg (SE = 0.0772). By the time the umbilicus had healed (<2 mo), the average length and mass had increased to 114.1 cm and 23.8 kg, respectively. Gestation period based on projections using LOB was 12 mo, but this was considered an overestimate. Calving was modal, centered in early July; an annual reproductive interval was indicated. Among the sexually mature females, 120 were pregnant, 55 were pregnant and lactating, 321 were pregnant with colostrum, and 33 were “resting.” By 3 July (95% CI =x? 1 d), 50% of births had occurred, during each of the seven years sampled. The ovulation rate was estimated at 0.914 ovulations per average reproductive year. Enlarged follicles and recent ovulations were observed in postpartum females in late July.     

LIFE HISTORY AND IN SITU GROWTH RATES OF ALEXANDRIUM TAYLORI (DINOPHYCEAE, PYRROPHYTA)

Alexandrium taylori Balech is a phototrophic marine dinoflagellate. It produced recurrent blooms during the summer months (July and August) of 1994 to 1997 in La Fosca beach (NW Mediterranean). In addition to a motile vegetative form, A. taylori had two benthic forms: temporary cysts and resting cysts. Temporary cysts were a temporally quiescent stage produced from the ecdysis of the vegetative cell in both natural populations and laboratory cultures. Temporary cysts may divide to form motile cells. Resting cysts had a thicker wall than the temporary cysts and had a red accumulation body. Gametes and planozygotes were also observed in laboratory cultures. Alexandrium taylori showed in situ diurnal vertical migration with an increase of vegetative cells in the water column in the morning through midday, with concentrations peaking in the afternoon followed by lower levels at night. Most vegetative cells lost their thecae and flagella, and with them their motility, turning into temporary cysts that settled in the early evening. The number of temporary cysts in the water column rose in the evening and at night. The temporary cysts gave rise to motile cells the following morning. Synthesis of DNA occurred in vegetative cells at night, and a preferential period of cell division occurred at sunrise. The estimated division rate in the field was 0.4–0.5 vegetative cells·day⁻¹. Temporary cysts had twice the DNA of a G₁ vegetative cell. The minimum in situ division rate of the temporary cysts was 0.14 day⁻¹. The role of the resting and temporary cyst population in the annual recurrence and maintenance of the A. taylori bloom is discussed.     

A MODEL LIFE TABLE FOR BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) FROM THE INDIAN RIVER LAGOON SYSTEM, FLORIDA, U.S.A.

Data gathered from 220 stranded bottlenose dolphins ( Tursiops truncatus ) in the Indian River Lagoon system, Florida, were used to derive a life table. Survivorship curves were fit to the data using Siler's competing-risk model and a maximum likelihood approach. Population growth was estimated to be between r = 0.0 and 0.046 based on the observed numbers of stranded dolphins. Variance in survival rates was estimated using an individual-based, age-structured population projection model. We estimate that the overall annual mortality rate for this population was 9.8% per year. Sex-specific differences in survivorship were apparent with females outliving males. The overall mortality curve resembles that of other large mammals, with high calf mortality and an exponentially increasing risk of senescent mortality. The inclusion of live-capture removals of individuals from this population did not significantly affect the estimation of survival parameters for most age classes.     

Age structure of strandings and growth of Lahille's bottlenose dolphin (Tursiops truncatus gephyreus)

This study describes the age structure and sex-specific growth patterns of Lahille's bottlenose dolphins (Tursiops truncatus gephyreus), a subspecies endemic to the Southwest Atlantic Ocean (SWAO). The ages of 120 animals collected in southern Brazil between 1976 and 2017 were determined. We found high frequencies of young animals, mostly males, with no sex bias among adults. A temporal change in the age structure of strandings was observed, and we conclude it is a consequence of increased bycatch rates of young dolphins after 2000. The oldest male and female were 27 and 44 years old, respectively, suggesting that females live longer than males in southern Brazil. Growth curve analysis using Gompertz and Laird-Gompertz growth models estimated asymptotic lengths of 316.5 cm for females and 351.6 cm for males, (reached around 13 and 18 years old, respectively), supporting sexual size dimorphism for the subspecies. A second growth pulse was identified for males. Our work highlights the benefit of long-term studies and contributes valuable information toward understanding the life history of Lahille's bottlenose dolphin. It will serve as baseline for future studies that seek to understand mortality patterns of bottlenose dolphins elsewhere and the effects of anthropogenic actions on the survival of these animals.     

THE EFFECTS OF PREDATION ON THE AGE AND SIZE OF MATURITY OF PREY

The effects of nonselective predation on the optimal age and size of maturity of their prey are investigated using mathematical models of a simple life history with juvenile and adult stages. Fitness is measured by the product of survival to the adult stage and expected adult reproduction, which is usually an increasing function of size at maturity. Size is determined by both age at maturity and the value of costly traits that increase mean growth rate (growth effort). The analysis includes cases with fixed size but flexible time to maturity, fixed time but flexible size, and adaptively flexible values of both variables. In these analyses, growth effort is flexible. For comparison with previous theory, models with a fixed growth effort are analyzed. In each case, there may be indirect effects of predation on the prey's food supply. The effect of increased predation depends on (1) which variables are flexible; (2) whether increased growth effort requires increased exposure to predators; and (3) how increased predator density affects the abundance of food for juvenile prey. If there is no indirect effect of predators on prey food supply, size at maturity will generally decrease in response to increased predation. However, the indirect effect from increased food has the opposite effect, and the net result of predation is often increased size. Age at maturity may either increase or decrease, depending on functional forms and parameter values; this is true regardless of the presence of indirect effects. The results are compared with those of previous theoretical analyses. Observed shifts in life history in response to predation are reviewed, and the role of size-selective predation is reassessed.     

CULTURE STUDIES ON THE LIFE HISTORY OF CHORDARIA LINEARIS (PHAEOPHYCEAE) FROM TIERRA DEL FUEGO,SOUTH AMERICA1

Studies of laboratory cultures of Chordaria linearis (Hooker et Harvey) Cotton from southernmost South America revealed that this species has an obligate sexual life history in which a macroscopic sporophyte alternates with a monoecious microscopic gametophyte. Sexual reproduction is isogamous and under photoperiodic control. Gametes are produced only in short days, whereas in long days, asexual zoospores are formed that recycle the gametophyte generation. Unfused gametes develop into gametophytes, and sporophytes originate only from zygotes. Unlike other sexual members of the Chordariales, gametes of C. linearis have a reduced stigma and do not show phototaxis. They are released at the beginning of the night, not in the morning. In nature, C. linearis seems to be regularly infected by a dictyosiphonalean epiphyte resembling the rare arctic species Trachynema groenlandicum (Lund) Pedersen. The epiphyte is responsible for previous contradictory results obtained in laboratory cultures of C. linearis. This is the first record of Trachynema in the southern hemisphere.