Spatial, seasonal and species variations of harmful algal blooms in the South Yellow Sea and East China Sea

The occurrences of harmful algal blooms (HABs), in terms of frequency and area in the Chinese coastal waters, have been increasing since 1980s and caused considerable economic losses. In the present study, we have analyzed spatial and seasonal characteristics of HAB events in the southern Yellow Sea and East China Sea along Chinese coast from 1933 to 2004. With a total 435 HAB records, the most frequent HAB occurrence area (FHA) is off the Yangtze River mouth and another two FHA areas are located south of the Yangtze River estuary along about isobaths of 30–60 m coastal water in the East China Sea. The time of HAB occurrence shifted during our study period: from autumn (August–October) before 1980s to July–August in 1980s, during May–July in 1990s, and May–June for the period of 2000–2004. Causative species were found to be different: Noctiluca scintillans and Skeletonema costatum were dominant causative species prior to 2000; and Prorocentrum donghaiense Lu was dominant from 2000 to 2004 and also caused large blooms in May. Trichodesmium sp. caused many HABs in autumn (August–October) prior to 1980s with only one HAB between 1980 and 2004. The changes of the dominant HAB species may have affected the timings of HAB occurrence, as well as the increasing HAB-affected areas in recent years.     

Reproductive cycles ofSebastes taczanowskii,compared with those of other rockfishes of the genusSebastes

Synopsis Seasonal reproductive cycles were examined in both sexes ofSebastes taczanowskii, captured in southern Hokkaido, Japan. The reproductive cycle in females was divided into four periods: recovery (July–August), vitellogenesis (September–March), gestation (April–May) and parturition (June). Spermatozoa were first observed in November in the ovarian cavity, where no structural specialization was present for sperm storage. Fertilization of oocytes appeared to occur in April, when the oocytes underwent a rapid process of final maturation. Embryos developed in the ovary quite synchronously and were released in June; empty ovaries indicated the rockfish has a single parturition. The reproductive cycle in males comprised five periods: resting (December–July), early maturation (February–May), mid-maturation (June–August), late maturation (September–October) and functional maturation (November). In November when active spermatogenesis had been completed, a large amount of spermatozoa was preserved in the sperm duct, and the males were therefore ready for mating. A comparison was made of the reproductive cycles of four species of the genusSebastes inhabiting southern and northern waters of Japan. It suggests that the northern species tend to prolong gametogenesis in both sexes while the southern species have the opposite tendency. Sperm storage in the ovary also tends to be longer in the northern than in the southern species.     

Sexual size dimorphism, growth and maturity of the Japanese fluvial sculpin,Cottus pollux (large egg type), in the Inabe River, Mie prefecture, central Japan

The population structure of the Japanese fluvial sculpin,Cottus pollux (large egg type), in the upper reaches of the Inabe River, Mie Prefecture, central Japan, was investigated by a mark-and-recapture method from July 1989 to January 1991. Breeding of the species occurred from mid February to early May, peaking from mid February to late March. The mean size of mature males observed in March 1990 was significantly larger than that of females, showing apparent sexual size dimorphism. Data analysis of the growth of 1658 marked individuals revealed that the species matured at 2 years of age in both sexes. Whereas 1 year old males reached ca. 50–70 mm SL, females were less than 50 mm SL at the same age, size dimorphism already being apparent. Immature males exhibited higher growth rates than females during their first and second years, some of the former outstripping mature males of the preceding year class in total length. After attaining sexual maturity, both males and females grew mainly from July to December, with no significant differences in mean growth rate between them. Sexual size dimorphism of the species seems to be attributable to different growth rates between the sexes during their immature stage.     

Differential allocation of protein resources to flight muscles and reproductive organs in the flightless wing-polymorphic bug, <Emphasis Type="Italic">Pyrrhocoris apterus</Emphasis> (L.) (Heteroptera)

Differences in the growth of dorsolongitudinal flight muscles and gonads in 1–28 days old long-winged (macropterous) and short-winged (brachypterous) adults of the firebug (Pyrrhocoris apterus L.) and the resource allocation to these organs were studied by means of total protein analysis. We found predominant allocation of food resources to flight muscles compared to reproductive organs in both macropterous males and females during the first 5 days of adult life. Subsequent histolysis of developed flight muscles coincided with increased total protein content in some reproductive organs. Initiation of intensive food intake after starvation or application of higher dose of methoprene on macropterous adults changed the resource allocation in favour of growth of reproductive organs and induced precocious histolysis of flight muscles. It indicates an involvement of juvenile hormone in wing morph-related differential allocation of resources in the bug. Increased total protein contents in the ovaries and accessory glands of starved macropterous females and males treated with methoprene, respectively, indicate that proteins derived from the methoprene-induced histolysis of the flight muscles are re-utilized for the growth of the reproductive organs. It is the first report of persistence of differential resource allocation to flight muscles and reproductive organs in the wing-polymorphic insects with non-functional macropterism.     

Seasonal changes in condition, reproduction and fecundity in the wild European rabbit (Oryctolagus cuniculus)

A total of 1248 rabbits ( Oryctolagus amiculus ) were shot on farmland in Cambridgeshire, UK over a period of three years. This provided pooled estimates of changes in reproductive and body condition and of fecundity during the annual cycle. Both males and females showed a significant annual cycle in reproductive condition as indicated by changes in the size of the gonads and accessory glands of reproduction. No females were pregnant during October, November and December, but males with active spermatogenesis were found during every month of the year. The distribution of pregnancies through the year showed that the reproductive season varied greatly between individuals. Peak fecundity occurred during April, May and June. On average, each female conceived 23.9 and suckled 17.2 young per breeding season. Proportionately more young died during the early stages of the reproductive season. The body weight of adult males, but not of females, varied seasonally. Body condition (kidney fat index) in adults was maximal at the start of the breeding season and minimal at the end.     

Annual variations in plasma sex steroid-binding protein and testosterone concentrations in the adult male little brown bat: relation to the asynchronous recrudescence of the testis and accessory reproductive organs

The annual reproductive cycle of the male little brown bat, in contrast to seasonal reproductive patterns of other mammals, is differentiated by an asynchronous recrudescence of the testis and the accessory reproductive glands. Spermatogenesis occurs during the summer, whereas fully stimulated accessory organs, stored epididymal spermatozoa, and sexual behavior are expressed later during a mating period that extends, albeit interrupted by hibernation, from late summer until early spring. To investigate whether changes in high affinity androgen-binding activity in the circulation are related to the delayed renewal of the accessory organs, plasma sex steroid-binding protein (SBP) and total testosterone (T) levels were measured throughout the year. From these data and determinations of association constants for T binding to SBP and albumin at both hibernating (4 degrees C) and active (40 degrees C) temperatures, estimates of the unbound ("free") and albumin-bound T fractions were made and correlated with changes in the accessory reproductive organs. Plasma SBP concentrations (mean +/- SEM) exhibited wide seasonal fluctuations: they were baseline in May (10 +/- 2 nM) following spring arousal, increased dramatically in June (184 +/- 24 nM), and reached peak levels in early July (262 +/- 29 nM), where they remained until August. In late August they began to fall (104 +/- 23 nM) and then returned to baseline during the hibernation period (October-April). Although total T levels were also elevated in June, it appeared that the unbound ("free") and the unbound plus albumin-bound T fractions did not increase until late July. Since the accessory gland weights did not begin to increase until late July as well, it was concluded that increases in the unbound and albumin-bound T fractions may be an important factor in the recrudescence of the accessories and that increased SBP activity in early summer may play a role in the regression and delayed renewal of these organs. However, what factor(s) maintain the accessory glands, epididymal spermatozoa, and sexual behavior during the breeding and hibernation periods when all T fractions were low are, as yet, undetermined.     

Mortality and reproductive patterns of wild European polecats<Emphasis Type="Italic">Mustela putorius</Emphasis> in Denmark

Despite its relative abundance and wide geographical range, the population dynamics and reproductive biology of the European polecatMustela putorius Linnaeus, 1758 are largely unknown as to the wild living. We therefore investigated age and reproductive status of 239 Danish polecats primarily killed in traffic or trapped during 1998–2004. Males comprised two third of all individuals in all age groups. Based on a static life table, apparent annual mortality was 68% during the first year of life, 33% during the second year and 65% from the third year in both sexes. The mean (± SE) litter size of 5.95 ± 0.62 (n = 18), estimated from placental scar counts, was significantly lower than litter sizes at birth reported for captive individuals but consistent with litter sizes reported for wild polecats in Russia. Female yearlings conceived at the same rate and produced litters of the same size as older individuals.Males had spermatozoa in their testes from February through August. Testes mass peaked in April and May, ie the same period when most females conceive. A lower prevalence of individuals with spermatozoa in yearlings suggests that most males postponed sexual maturity to two years of age.     

Reproductive cycle of <Emphasis Type="Italic">Antedon mediterranea</Emphasis> (Crinoidea,Echinodermata): correlation between morphology and physiology

Gonads of the mediterranean crinoid Antedon mediterranea were analyzed in order to reconstruct their histological organization. The tissue arrangement resembled that previously described in other crinoids. Five reproductive stages were identified in both males and females: recovery, growing, premature, mature, spent. Sexually dimorphic characters were observed at the gonopore level. Hermaphroditic individuals were never detected. There were novel findings concerning somatic accessory cells of the gonads. The reproductive cycle periodicity was indicated by analysis of reproductive stage frequencies in the period 2003–2005: spring and winter were the seasons with highest and lowest maturity levels, respectively. A role in the regulation of reproduction was hypothesized for testosterone and 17β-estradiol, which were found to be present in A. mediterranea tissues and to vary during the reproductive cycle, thus suggesting a correlation between steroid levels and morphologically recognizable reproductive stages.     

Seasonal and daily cycles in sound production associated with spawning in the weakfish,Cynoscion regalis

Synopsis Hydrophone recordings were made to document the daily and seasonal cycles of weakfish,Cynoscion regalis (Sciaenidae), sound production in the Delaware Bay. Recordings were made at three stations perpendicular to the shore and rated qualitatively on a scale of 0–4. ‚Drumming’ (sonic muscles, males only) and ‚chattering’ (pharyngeal stridulation, both sexes) were tallied separately. Weakfish were collected from the field throughout the spring and summer to monitor the reproductive status of the population. A clear seasonal trend was noted in both drumming and chattering activities. Drumming activity rose abruptly in mid-May to maximal levels, which were maintained through late June, then dropped off in July and ceased in August. Chattering activity began abruptly in late June, then rose through July and remained high in August. Seasonal drumming activity was more intense at the inshore station. On a daily scale, drumming activity was at its lowest level during the early to mid-morning, then increased to maximal levels in the early evening and remained high until the following morning. There was no daily trend in chattering activity. Daily drumming activity was also most intense at the inshore station. Male and female reproductive readiness, determined by gonadosomatic indices, sperm motility and plasma androgen levels, peaked within the period of maximal seasonal drumming activity.     

Some reproductive traits of the Tristan klipfish, Bovichtus diacanthus (Carmichael 1819) (Notothenioidei: Bovichtidae) from Tristan da Cunha (South Atlantic)

The reproductive biology of the Tristan klipfish, Bovichtus diacanthus, was investigated by macroscopic and histological analyses of the gonads. Fish samples were collected in tide pools at Tristan da Cunha in July 2004. Most specimens of both sexes were developing, or sexually mature, with a gonadosomatic index (GSI) of 7.0–9.2% in females and 0.2–0.6% in males. Histologically, testes showed a random distribution of spermatogonia along the lobules, a condition defined as the unrestricted spermatogonial type. Ripe males exhibited lobules with all spermatogenic stages of development from spermatogonia to spermatozoa. In mature females, the ovarian follicles consisted of three main cohorts of oocytes of different sizes; the smaller one represented by previtellogenic oocytes of 15–150 μm and the other two by yolked oocytes measuring, respectively, 300–1000 and 800–1500 μm. The overlap between the stock of advanced yolked oocytes and the early yolked oocytes was low, decreasing progressively with final maturation. As a result, B. diacanthus was considered a batch spawner, with a spawning season extending from July to August onward. Batch fecundity, based on the most advanced yolked oocytes, was 2,047–8,317 mature oocytes/female, whereas the relative fecundity was 77–141 mature oocytes/g. In the light of the phyletically basal position of bovichtids in the suborder, the reproductive traits of B. diacanthus were compared with those previously described in other Antarctic and non-Antarctic notothenioids.     

Biological traits of naturally induced hybrid individuals of two gizzard shads, <Emphasis Type="Italic">Nematalosa come</Emphasis> and <Emphasis Type="Italic">N. japonica</Emphasis>, in coastal waters around Okinawa Island,Ryukyu Archipelago,southwestern Japan

The age, growth, reproductive condition, and occurrence of natural hybrids of two Nematalosa species around Okinawa Island were examined using 128 specimens obtained from April 2003 to June 2004. Standard length (SL) reached approximately 150–210 mm within the first 2 years, and then remained stagnant. The maximum age for both sexes was ca. 5 years old. Maturity sizes and ages were estimated to be at least 173.2 mm SL and 2 years old for females and 192.6 mm SL and 3 years old for males. Spawnable individuals were mainly observed from January to March based on histological observations of gonads. Natural hybrids appeared at all sampling sites except for the Haneji Inlet and were dominant at Makiminato (in south-central Okinawa Island). Their incidence was also quite high (66.9%) in the Makiminato population, when compared with records for other marine fishes around Japan. In Okinawa Island, these shallow areas are rapidly decreasing in size because of recent reclamation and land exploitation. Hybrid production may be caused by not only the reproductive biology and sympatric distributions of the parent species but also recent environmental changes.     

Seasonal Variation in Diel Production Pattern of Centropages tenuiremis in Xiamen Waters, China

The seasonal variations in diel production pattern, and egg hatching time of the copepod Centropages tenuiremis in Xiamen waters, China, were investigated between January and June of 2003. The results show that in the winter–spring (January to early May) the adult females tended to lay subitaneous eggs at night, while in the beginning of summer (late May–June) they tended to lay diapause eggs as well as subitaneous eggs during the daytime. The egg hatching time negatively correlated with water temperature. These results, combined with the fact that C. tenuiremis migrates vertically in Xiamen waters, may explain the reproductive strategy of this dominant species in winter–spring.     

Sexual dimorphism and intercorhort variation in reindeer calf antler length is associated with density and weather

We analysed intercohort variability of live weight and antler length of 5,123 reindeer calves. We further assessed the influence of climate and density on the interannual variation in antler length, and discussed sex-specific resource allocation and response to climate variability. Antler length varied significantly among years and between sexes, with interaction between year and sex. Body weight and antler length were highly positively correlated, showed similar intercohort variability, and had a strong allometrical link, suggesting that antler length could be an equally reliable measure of calf condition as live weight. We found a relative measure of antler length (i.e. antler length corrected for the allometric effect of body mass) to be positively influenced by increasing density and May–June precipitation, and also decreasing May–June temperature. We attributed the effect of early summer weather to its influence on forage availability and quality as well as the level of parasitic insect harassment. Gender difference in both the allometric exponents and the interannual variability suggest that young males and females may have different tactics for relative resource allocation towards growth of antlers as compared to body mass. Because antlers are costly to produce, they may be an honest signal of individual quality for both sexes. However, we found gender-specific allometry, as female calves more than males appear to prioritize their antler growth over body mass, especially when resources are limited. Thus, our results suggest that environmental variation may influence the extent of sexual dimorphism in antler length. Electronic Supplementary Material Supplementary material is available for this article at     

Seasonal changes of the at-sea distribution and food provisioning in rhinoceros auklets

Central-place foraging seabirds increase food-loads and decrease meal frequency when they forage in areas that are distant from the breeding colony. In 2001–2002, we studied the seasonal changes in at-sea distribution, food-load mass, meal frequency, and fledging mass in rhinoceros auklets (Cerorhinca monocerata), which forage in coastal waters during the day and feed their chicks at night. In both years, greater numbers of auklets were observed flying in northern waters that are more distant from the colony in June (65 km) and July (65–66 km) than in May (38–47 km). In July of both years, many auklets flew northward across the transect set 65–120 km north of the colony at sunrise; the birds returned south again at sunset, indicating that they foraged in waters outside the study area. This seasonal northward movement of the foraging area may reflect the migration of their main prey item, the Japanese anchovy (Engraulis japonicus), which move with the Tsushima Warm Current flowing from the southern Sea of Japan. Food-load mass did not increase seasonally. In both years, the estimated daily meal frequency was lower in July than in May or June, partly because of the increased foraging distance in July. Late-hatched chicks also displayed lighter fledging masses than early chicks in both years. We suggest that late breeders are required to forage at great distances for longer periods, which may result in decreased meal frequency and lighter fledging mass of their chicks.     

Autodetection and chemistry of female and male pheromone in both sexes of the tiger moth Panaxia quadripunctaria

Female moths of Panaxia quadripunctaria PODA (Lepidoptera, Arctiidae), produce (Z,Z)-6,9-heneicosadiene (I) as the major and (Z,Z)-6,9-eicosadiene (II) as the minor component of a putative pheromone. Related compounds occur in trace amounts. The abdominal scent glands contain 5–10 μg of (I) and 50–100 ng of (II). Recordings of electroantennogram (EAG) responses to (I), (II), and to female glands are of equal amplitude in both sexes. Females are thus capable of pheromone autodetection in contrast to the majority of moths where females are considered to be anosmic for their own attractant. The EAG threshold to (I) was below 1 ng at the odour source. The odour of the male scent gland (corema) elicited significant EAGs in both sexes. The chemical contents of coremata varied with the provenience of the moths. A variety of ethyl esters was always found, yet hydroxydanaidal (up to 20 μg/corema) and traces of danaidal, only in some samples. All these scents might be components of a male pheromone. Peculiar scent scales on the coremata are exposed during the extrusion. Antennae of both sexes have similar inventories of trichoid sensilla. Accepted: 11 July 1997     

Seasonal succession of Copepoda in the Bahía Blanca estuary

The abundance and species composition of Copepoda with respect to other mesozooplanktonic groups were studied at the harbour of Ingeniero White in the inner zone of the Bahfa Blanca estuary, between July 1990 and August 1991. Maximal copepod abundances of 4.7 × 10 m^–3 and 4.9 × 10 m^–3 were observed in January 1991 and May 1991, respectively. Minimal abundances of 6 m^–3 were found in June 1990. Acartia tonsa was present throughout the year with high dominance in summer-autumn (December to May). Eurytemora affinis was present from July to October 1990 (first pulse) and from July to September 1991 (second pulse). Euterpina acutifrons was most abundant during spring 1990, whereas Paracalanus parvus was most abundant during winter-spring (July–October) 1990 and April–May 1991. The rest of the copepods were observed during winter and spring 1990 and July–August 1991. Calanoides carinatus and Labidocera fluviatilis, both species from the outer estuarine waters, were only found on two sampling dates. The proportion of meroplanktonic forms was high in certain months of the annual period considered. Differences between the copepod seasonal succession studied here and those observed during several years in the 1980's are discussed.     

Relative growth and reproductive cycle in two populations of <Emphasis Type="Italic">Bolinus brandaris</Emphasis> (Gastropoda: Muricidae) from northern Tunisia (Bizerta Lagoon and small Gulf of Tunis)

A study on the relative growth and reproductive cycle of the purple dye murex (Bolinus brandaris) was performed from March 2007 to February 2008 in two populations with contrasting imposex levels (Carthage Byrsa — CB in the small Gulf of Tunis and Menzel Abderrahmane — MA in the Bizerta Lagoon). Both populations presented balanced sex ratios. Comparison of allometric relationships established between linear and ponderal variables (sexes confounded) revealed higher growth in CB than in MA. Mature individuals were found throughout the year, except for September in MA. Spawning periods occurred from March–April to May and from June to August in both sites. Spawning was associated to an increase in seawater temperature. Besides increasing the current knowledge on the biology of B. brandaris from the southern Mediterranean, the information gathered in the present study constitutes a useful baseline for the sustainable management of local wild stocks, namely by prohibiting collection of snails during the spawning season.     

Reproductive ecology of the lacertid lizard Podarcis bocagei

This paper presents data on aspects of the reproductive ecology of a population of Podarcis bocagei in northwestern Spain, as monitored over a two-year period (1990–1991) Data were obtained principally on the basis of mark-recapture experiments, but also from laboratory hatching studies Mating took place between the end of March and July During the laying period, from May to July, 8 5% of reproductive females produced three clutches, 52 1% two clutches, and 39 4% one clutch In general, single clutches were produced by small females Only a small proportion of large females produced three clutches Mean clutch size was 4 8 eggs (range 4–7) in May, 4 3 (2–6) in June and 3 9 (2–4) in July There was sigmficant variation in the mean snout-to-vent length (SVL) of females laying in each month of the season Both clutch size and mean single-egg volume increased with mother's SVL There was a significant partial correlation between egg volume and clutch size when both mother's SVL and month of laying were held constant There was no significant between-year variation in clutch size, breeding females' SVL, egg weight or relative clutch mass A delay in the timing of reproductive events in one year (1991) is attributable to adverse weather conditions during early spring Hatching occurred between July and September Hatch success (as estimated in 1989, 1990 and 1991 from natural nests at the study site) was high, ranging from 83% in 1991 to 91% in 1989 The mean SVL of female hatchlings was greater than that of male hatchlings By contrast, adult females had lower mean SVL than adult males     

Seasonal changes in reproductive and physical condition, sexual dimorphism, and male mating tactics in the jewelled blenny Salarias fasciatus

To investigate seasonal changes in reproductive and physical condition, sexual dimorphism, and mating tactics in the jewelled blenny Salarias fasciatus, monthly collections were conducted on the fringing reef in northern Okinawa, Japan. Monthly variation in the female gonadosomatic index suggested that the breeding season of this species is from April to June. The physical condition and hepatosomatic index of both sexes considerably deteriorated during the course of the breeding season. Such declines may be primarily due to egg production in females and brood care in males. Males’ elongated anal spines were longer than females’, but no other apparent sexual dimorphisms were detected, indicating that S. fasciatus exhibits a low degree of sexual dimorphism. Examinations of testes size and the testicular gland area during the estimated breeding season revealed that the gonadosomatic index values of smaller males did not differ from those of larger males. This result may differ from other blenny species that exhibit alternative male reproductive tactics. However, patterns of male testicular glands of S. fasciatus were similar to those of other blennies with alternative tactics, i.e., smaller males had poorly developed testicular glands compared with larger males.     

Reproductive biology of the predator Macrolophus caliginosus: Effect of age on sexual maturation and mating

Macrolophus caliginosus is a polyphagous mirid bug native to the Mediterranean area where it is widely used as a biological control agent, both in protected and open-field vegetable crops. Its reproductive biology remains largely unknown and a better understanding of it will improve mass rearing and release strategies. In the present work, we studied the development of reproductive organs in females and males and how age conditioned receptiveness to mating in both sexes.Females with mature eggs in their ovarioles appear 3–4 days after adult molt with a similar pattern of ovary maturation in virgin females as in females that were kept with males of the same age. Newly molted males were found to already have active sperm in their seminal vesicles but their accessory glands did not completely develop until 3 days later. Receptivity for copulation paralleled ovarian and accessory gland maturation.