Comparative population biology of Uca rapax (Smith, 1870) (Brachyura,Ocypodidae) from two subtropical mangrove habitats on the Brazilian coast

The structure of two populations of the fiddler crab Uca rapax in two subtropical mangrove habitats near Ubatuba, State of São Paulo, Brazil were compared. The size–frequency distribution, sex ratio, and recruitment were evaluated. Sampling was performed monthly from April 2001 to March 2002 in the Itamambuca and Ubatumirim habitats. Crabs were caught manually for 15?min by two collectors during low tide. The carapace width of each crab was measured with a digital caliper, and the sex and ovigerous state were recorded. The median size of the carapace width of males was greater than that of females at both sites (P<0.05). The median size of the crabs from Itamambuca was larger than at Ubatumirim (P<0.05). Only 28 ovigerous females were obtained from both mangroves, which suggested that females might remain in their burrows during the incubation period. The highest recruitment pulse occurred in winter for both populations, probably as a consequence of high reproductive activity during summer. The sex ratio in the size classes showed an anomalous pattern, with a higher frequency of females in the intermediate size classes. This may be related to a greater energy requirement for reproduction in females, thus delaying growth. The variable environmental conditions to which Uca rapax populations are subject appear to act directly or indirectly on the population, causing variations in growth and reproductive processes in the different populations investigated here.     

Life cycle and population structure of the terrestrial isopod Hemilepistus klugii (Brandt, 1833) (Isopoda: Oniscidea) in Iran

The life cycle and population structure of Hemilepistus klugii were studied in a population in Varamin, Iran. The population was sampled monthly (or fortnightly during the breeding season) from February 2008 to June 2009 and a total of 7015 individuals, comprising 1069 males, 1079 females and 4867 juveniles, were collected. As in other Hemilepistus species, five distinct phenophases, namely pair formation, gestation, hatching, growth and stationary, were recorded during the life cycle of H. klugii. The overall sex ratio was 1 : 1 but varied over time. Ovigerous females were observed only in April, indicating a seasonal and very short breeding period. With a short lifespan after breeding, females demonstrated true semelparity. The mean cephalothorax width for ovigerous/post-ovigerous females was higher in 2008 than in 2009. These females attained the largest size in the population throughout the year. The number of eggs per female ranged from 28 to 147 (mean ± SE, 78 ± 1.8). There was a positive correlation between female size and fecundity. Recruitment occurred in late April and resulted in the highest population density in this month, whereas the lowest densities were observed during November to January. Despite a high percentage of ovigerous females carrying undeveloped eggs (72.3%), intramarsupial mortality was low (3.5%).     

Population structure and breeding season of the hermit crab Diogenes brevirostris Stimpson, 1858 (Decapoda,Anomura, Diogenidae) from southern Mozambique

In this study the population dynamics of the diogenid hermit crab Diogenes brevirostris is evaluated focusing on size structure, sex ratio and breeding season. Crabs were randomly taken on a monthly basis from January to December 2003 at Costa do Sol, Maputo Bay, southern Mozambique. A total of 622 crabs was obtained of which 290 were males (46.6%), 170 were non‐ovigerous females (27.3%) and 162 were ovigerous females (26.1%). The overall size frequency distribution was unimodal for males, non‐ovigerous females and ovigerous females. The overall sex ratio (1:1.15) differed from the expected 1:1 ratio. Sexual dimorphism was evidenced by the larger size attained by males in relation to both ovigerous and non‐ovigerous females. Breeding took place year‐round with three peaks of spawning (March, August and December). Despite the high reproductive activity, young recruits were scarce in the population. The present results suggest that the study area is suitable for reproduction and growth whereas recruitment may take place in different areas from that occupied by the adults.     

Aspects of the biology of the jonah crab,Cancer borealis Stimpson, 1859 in the mid-Atlantic Bight

Summary

Jonah crabs, Cancer borealis, were collected in October 1971, June 1973, and March and April 1974 during trawl surveys of the continental shelf of the mid-Atlantic Bight and the shelf and slope east of Beaufort, North Carolina. In 171 trawls made from the M/V Blesk, R/V Columbus Iselin, R/V Albatross IV and R/V Eastward, 1626 jonah crabs were captured. Crabs were contagiously distributed within a depth range of 20–400 m. Maximum abundance occurred within 150–400 m and 8–13·9°C.

Male crabs ranged from 12 to 175 mm in carapace width; females from 13 to 152 mm. Three modal size groups for males and females were recognized: 13–40 mm, 41–80 mm and 81–110 mm. There was a fourth group of male crabs over 110 mm width. Crabs 40 mm were most abundant at depths of 75–150 m; crabs 41–80 mm were not captured in depths < 150 m, but were the dominant group in strata > 150 m. Larger crabs (81–110 mm) occurred from 40 to 400 m and reached maximum numbers at 150–400 m. Male crabs ≥ 111 mm were found only in 150–400 m.

Male crabs predominated in June. Sex ratios (M:F) ranged from 1·1:1 to 17:1. In October the ratios ranged from 1:16 to 2·4:1. In March and April the ratios were 2·9:1 and 1·9:1, respectively. In most cases the ratios were significantly different from 1:1.

The species was actively moulting in June, but recent or incipient ecdysis was not observed in October. Only one recently moulted crab was noted in March.

Gonad development in June was related to size. Most crabs ? 80 mm width were undeveloped or only slightly developed. Mature gonads were seen only in crabs ≥ 100 mm width. Testes and vasa deferentia of most males ≥ 150 mm were well to very well developed. No ripe ovaries were seen and no ovigerous individuals were taken in June. One berried female was observed in March.

The incidence of fouling organisms on crabs reflected the moulting history of the crabs. Sixty per cent of crabs in anecdysis and 14% of those in postecdysis were fouled. The predominant organism was the lepadid barnacle, Poecilasma inaequilaterale Pilsbry, which was attached to the gills in the branchial chamber.     

Seasonal reproduction in deep-sea Crustacea (Isopoda: Asellota)

A collection of Crustacea Isopoda (suborder Asellota) from a 10-year sampling programme in the Rockall Trough, NE Atlantic (54°40′N, 12°15′W) was analysed for evidence of breeding seasonality. No evidence of seasonal activity was found — adults and newly released juveniles were present throughout the year — but there was a strong seasonal pattern for breeding intensity. A significantly higher proportion of females was brooding during the winter months (25%) compared to the summer (5%), and the percentage of females brooding varied significantly with depth. The breeding pattern was synchronized to the seasonal deposition of organic detritus known to occur during the summer in the NE Atlantic. There were more newly released juveniles in samples during the summer than during the winter, with most females appearing to release their young at the time the deposition began. This deposition appears to be a major seasonal factor dominating the life-cycles of most benthic species in the Rockall Trough. Juvenile settlement for a range of taxa (echinoderms, molluscs and crustaceans) occurs while the detritus is present and most species maximize vitellogenesis at this time.     

Breeding season of the hermit crab Dardanus deformis H. Milne Edwards, 1836 (Anomura,Diogenidae) in Maputo Bay,southern Mozambique

The breeding season of the hermit crab Dardanus deformis is studied based on the occurrence of ovigerous females, in relation to temperature and rainfall. Monthly samples were obtained between January and December 2003 at Costa do Sol, Maputo Bay, southern Mozambique. A total of 331 female individuals was analysed of which 164 were non‐ovigerous females and 167 were ovigerous females. Dardanus deformis breeds continuously in the study area with peaks of spawning from August to October and a slight decrease from May to July. Both temperature and rainfall were positively correlated with percentages of ovigerous females. Multiple linear regressions suggest that rainfall is the main factor controlling the breeding activity of D. deformis in Maputo Bay. This species may have a rapid and high reproductive activity in the study area as observed by the higher number of ovigerous females relative to non‐ovigerous females which may contribute to a constant larval supply and recruitment of this species in the study area.     

Reproductive features of the deep water hermit crab Sympagurus dimorphus (Anomura: Parapaguridae) inhabiting pseudoshells in the SW Atlantic Ocean

We herein provide information on reproductive aspects (the gonopore morphology of both sexes, the size of embryonic eggs and the fecundity) of the hermit crab Sympagurus dimorphus from deep waters of Argentina. Sampling was performed in different oceanographic and fishery campaigns between 2007 and 2010, at 38°01′–39°03′S, 55°–56°05′W, 85–150 m depth, in the SW Atlantic Ocean. Mean shield length (SL) of females was 9.41 ± 1.68 mm (range: 6.6–10.5 mm). Female gonopores measured 0.74 ± 0.10 mm (range: 0.45–0.90 mm), were oval in shape, and were more rounded and larger than male gonopores (0.51 ± 0.007, range: 0.4–0.63 mm). The egg volume for each of the three stages of embryonic development was 0.94 ± 0.20 mm³ for stage I, 1.14 ± 0.31 mm³ for stage II, and 2.07 ± 0.41 mm³ for stage III. Egg volume doubled from the initial to the final stage of the embryonic development. The fecundity (number of eggs) varied from 831 (6.62 mm SL) to 2246 (10 mm SL) for females carrying eggs in stages I+II, and between 158 (158 mm SL) and 1279 (9.4 mm SL) in stage III. The reproductive characteristics of the observed profile are intimately related to S. dimorphus use of a pseudoshell resource and a deep water habitat.     

The carboniferous fossil lycopod Ulodendron landsburgii (Kidston) comb. nov.

Summary

A data gathering system controlled by microcomputer, recording swimming activity, is described. Prior to the breeding season, in a normal day and night regime, the delta prawn Palaemon longirostris shows a circadian swimming rhythm with peak activity at night. As the ovaries ripen and the prawns mate there is evidence of an additional tidal swimming rhythm. Females carrying eggs revert to nocturnal circadian swimming only. In ovigerous females the circadian swimming rhythm persists in continuous darkness with a free-running period of between 22 and 23 hours. The closely related and sympatric species Palaemonetes varians has similar patterns of swimming behaviour. It is suggested that the absence of newly hatched palaemonid larvae in the estuary is a result of the interaction of these adult swimming patterns with tidal flow and nocturnal hatching.     

Reproductive biology of Scinax fuscomarginatus (Anura,Hylidae) in south‐eastern Brazil

The present study describes the reproductive biology of Scinax fuscomarginatus in a remnant of Cerrado in south‐eastern Brazil. Observations were made between September 2002 and March 2004 at Estação Ecológica de Itirapina, State of São Paulo, south‐eastern Brazil. Breeding activities occurred in lentic and temporary bodies of water during the rainy season. Scinax fuscomarginatus exhibited a prolonged breeding pattern and a lek mating system. Males were smaller than females and defended individual calling areas through acoustic and physical interactions. Resident males consistently won encounters, but did not differ in size or mass from intruder males. Satellite behaviour was observed, but no female or amplected pair interception was registered. Scinax fuscomarginatus exhibited low operational sex ratios and the general reproductive mode in which eggs are laid in the water and tadpoles are aquatic. Amplexus was axillary and the eggs were deposited at the bottom of temporary ponds. Details on oocytes, egg masses, and eggs are included.     

Diversity and taxonomy of intertidal Bryozoa (Cheilostomata) at Akkeshi Bay,Hokkaido, Japan

We found 39 cheilostome species among more than 7000 specimens collected at 10 intertidal sites in rocky habitats along the shore of Akkeshi Bay, eastern Hokkaido Island, Japan. These species are herein described in detail and illustrated by scanning electron microscopy. Nine species (23% of total) are described as new (Electra asiatica, Callopora sarae, Conopeum nakanosum, Cauloramphus cryptoarmatus, Cauloramphus multispinosus, Cauloramphus niger, Stomachetosella decorata, Microporella luellae, and Celleporina minima), and 21 species (54%) are reported for the first time from Japan. Species richness ranged from eight to 29 species per study site. A TWINSPAN analysis showed the species fell into nine groups defined by the local pattern of distribution. A cluster analysis of study sites based on similarity of species composition showed three faunistic groups distributed geographically: in Akkeshi Lake, along the eastern‐central shore of the bay, and at the mouth of the bay. Species richness in estuarine Akkeshi Lake was low, with a species composition very different from the outer bay. Most cheilostomes were found on rock and shell substrata, but uncommonly occurred on concrete walls, algae, hydroids, tubes of polychaetes, other bryozoans, and anthropogenic debris. Of the 39 species found, 33 (85%) contained embryos during the collecting periods, 2–7 June and 3–6 July 2004. The biogeographical composition of intertidal cheilostomes at Akkeshi Bay included species with Arctic‐Boreal (28%), Boreal (59%), and Boreal‐Subtropical (13%) distributions. The overall species richness of intertidal cheilostomes was two‐thirds that documented intertidally in a comparable study at Kodiak, Alaska, a locality 15° higher in latitude. We attribute the lower richness at Akkeshi to differences in the nearshore marine environment between the two localities.     

Notes on Geryon tridens (Decapoda,Brachyura) from west of Ireland

Summary

One hundred and eighty males and 23 female specimens of Geryon tridens from 60 to 110 miles west of Ireland were examined in July 1968.

The carapace length/width relationship was calculated as;

and

where y = carapace length and x = carapace width.

Eleven per cent of the males captured had moulted recently, and one female had recently carried eggs.

The average size of crabs was found to increase from east to west, and it is suggested that the present sample is taken from the western side of the main population. There was no relationship between average size and the depth of the water in which they were caught.     

The polychaete fauna of Careel Bay,Pittwater, New South Wales,Australia

Summary

The polychaete fauna of Careel Bay, Pittwater (33°37′S; 151°20′E) a sheltered estuarine area just north of Sydney, New South Wales, Australia is described. Some 57 species are described of which Parahalosydna chrysostichtus, Nereis posidoniae, Malacoceros divisus. Polydora penicillata. Prionospio multicristata. Nerinides vexillatus, Caulleriella tricapillata, Notomastus torquatus, Amphicteis dalmatica and Streblosoma acymatum are new species and 11 are new records for Australia. All previous Australian records are given for each species.     

Seasonal abundance and life cycle of Archaeomysis articulata (Crustacea: Mysidacea) on a sandy beach of western Hokkaido,Japan

Abundance and life cycle of the sandy beach mysid Archaeomysis articulata Hanamura were investigated based on seasonal collections over 2 years in the surf-swept intertidal zone of an open sandy beach in Ishikari Bay, western Hokkaido, Japan. The number of mysids in the intertidal zone increased from winter to spring, reaching its maximum in summer to autumn (average >2500 ind. m^-2), and decreased considerably towards the end of the year. The abundance was maintained at a minimal level (<200 ind. m^-2) throughout the winter. The breeding season was March to November, during which the liberation of young was most intensive from late April to mid-October. Three alternate generations, including overwintering, spring and summer generations, were suggested from field observations. Archaeomysis articulata is primarily iteroparous; only a restricted number of breeding females could produce more than two broods. The life span was estimated to be 7–9 months for the overwintering generation and 2.5–3.5 months for the spring–summer generations. The sex ratio fluctuated at samplings, with a tendency toward female dominance (overall mean=54%). The number of embryos carried by a single female ranged from 16 to 94, tending to increase with increasing size of females. The size of egg-like embryos varied seasonally from 0.45 to 0.54mm, being largest in spring and smallest in summer, with no correlation to the length of females; water temperature is considered an important factor in regulating the size of eggs. The embryonic development time was estimated to be 1.5 months for the spring generation (water temperature 5–10°C), and much shorter than this for the summer and overwintering generations. The mortality rate during embryonic development was estimated to be 7–18%.     

Breeding biology of the Sayaca Tanager (Thraupis sayaca) in southeast Brazil

ABSTRACT

Thraupis is a genus of the American endemic Thraupidae (subfamily Thraupinae), comprising seven species that inhabit tropical forests to urban centres. The Sayaca Tanager (Thraupis sayaca) is a disturbance-tolerant species of high representativeness in plant-frugivore networks, but information on its breeding biology is scarce and often restricted to non-systematic surveys. We studied the breeding biology of the T. sayaca, following 39 active nests in a periurban area of southeast Brazil during two breeding seasons (2017/2018, 2018/2019). The breeding season ranged from early September to middle December, and the nests were placed in native and exotic plants and human buildings (nest height above ground: 3.35 ± 1.73 m, mean ± SD). Only females incubated and brooded, but both adults built the nests, fed the nestlings, and removed their faecal sacs. Clutch size was 2.86 ± 0.38 eggs and nest attentiveness was 71.2%. The incubation and nestling periods were, respectively, 13.4 and 17.4 days. Males and females did not differ on nestling provisioning and nest sanitation rates. Nestling provisioning (13.35 ± 6.25 trips/hour) increased with nestling age, while mean brooding time was 37.2% and decreased with nestling age. Apparent nest success was 38.7%, and nest survival according to the Mayfield method was 27.2%. Five nests (20.8%) were parasitised by the Shiny cowbird (Molothrus bonariensis), and we recorded five events of nest-site reuse. We concluded that the most remarkable breeding traits of T. sayaca in comparison with close-related tanagers are the use of anthropogenic nest sites, the higher clutch size and number of feeding trips, and the longer nestling period.     

The salinity during larval development affects the dispersion in adults of the tree-climbing crab Aratus pisonii

Adults of the tree-climbing crab Aratus pisonii occur in estuarine regions with a range of salinity of 0–35. However, the larvae cannot complete the development in a wide range of salinities. A study about the effect of salinity on the larval development was conducted in order to infer about adult dispersion and occurrence in a wide range of salinity. Two experiments were conducted: (1) from zoae I to megalopae stage and (2) from megalopa to juvenile stage. Larvae from eight females from Paranaguá Bay, Paraná, Brazil were obtained. After eclosion, for the first experiment, 100 zoea larvae from five females were acclimated, individualized and transferred to small aquariums with five distinct salinity treatments (S0, S5, S15, S25 and S35). For the second experiment, 50 megalopae from three females were individualized in aquariums in the same salinity treatments. Both experiments were conducted in incubator BOD with a constant temperature of 25°C and photoperiod of 12 hours (light/dark). Larvae were fed daily with eggs and naupli newly hatched of Artemia sp. The salinity affected the survival rate during the development in both experiments. Higher survival from zoea I to megalopa stage occurred in salinities 25 and 35 PSU, while from megalopa to juvenile stage in salinities 15 and 25 PSU. In both experiments the larvae did not tolerate low salinities as adults, with total mortality in S0 and S5. Our results suggest that the species have a larval export strategy of zoae larvae to oceanic regions (higher salinities) and megalopae needed to return to estuarine areas with intermediate salinities to complete the development. The occurrence of adults in estuarine areas with low (< 5 PSU) or high (> 25 PSU) salinities most likely occur after the metamorphosis to the juvenile stage by terrestrial dispersion or at the stage of megalopa (marine dispersion) during favourable weather events.     

Occurrence and influence of Orbione halipori Nierstrasz and Brender à Brandis (Isopoda: Bopyridae) on Metapenaeus joyneri (Miers) (Decapoda: Penaeidae) from the Zhujiang estuary,China

The bopyrid parasite Orbione halipori was recorded for the first time from Metapenaeus joyneri. Morphometric analysis indicated that infested male and female shrimp have slightly, but significantly, lower body weight than uninfested shrimp of the same carapace length. While the parasites sterilize their hosts, the low infestation rate (0·53%) appears not to pose a threat to the shrimp fisheries in the Zhujiang estuary.     

Embryonic development and reproductive strategy of Pseudorchestoidea brasiliensis (Amphipoda: Talitridae) at Prainha Beach,Brazil

The embryonic development and reproductive strategy of Pseudorchestoidea brasiliensis, a talitrid amphipod of the supra- and midlittoral zones, were investigated by combining collections from June 1993 to May 1995 at Prainha, Rio de Janeiro (23°05′S and 43°25′W). The initial stage of embryonic development (I) was most frequent and was seen in about 70% of ovigerous females. Mean embryo volume in the final stage of development was almost twice that in the initial stage. Brood mortality between embryonic Stages I and IV was estimated at 11.42%. Multivoltism, continuous reproduction, low brood mortality (may be caused by better parental care with offspring) and the larger number of females than males in the population were indicated as compensating factors for the low fecundity observed in P. brasiliensis.     

Studies on the life cycle of the cicadellid bug Empoasca dolichi Paoli,in Southern Nigeria

Summary

Studies carried out on the biology of E. dolichi Paoli showed that its eggs are palegreen to creamy white, elongate and often curved, and have a mean length and width of 0·84 mm and 0·16 mm respectively. The egg-incubation period averaged 8·3 days under uncontrolled insectary conditions of 21–32°C and 45–95% relative humidity, while the life-cycle from egg to adult averaged 17·5 days. In the insectary, mating in E. dolichi usually started between the third and sixth day after adult emergence. Over 56% of observed individuals mated on the 4th day. The observed diurnal mating period was mainly within 05·30–09·00 hours and 16·00–20·00 hours local time, with an average copulation period of 65·7 min. The mean pre-oviposition period of 3·0 days for 23 mated females was significantly shorter than 4·0 days for 21 unmated females. An average of 116 eggs and 96 eggs were laid by mated and unmated females respectively, but the fecundity rate (3 eggs/day of total life-span) of mated females was significantly higher than that (2 eggs/day) of unmated females. Unmated females lived longer (mean=49·7 days) than mated females with a mean of 38·3 days. The average life-span for mated and unmated males was 31·0 and 32·4 days respectively. Insectary and field observations revealed that females of E. dolichi preferentially lay their eggs into the stems, leaf-veins and leaf petioles of cowpea plants. Only mated females of E. dolichi laid viable eggs, and the observed male: female sex-ratio of their progeny in the insectary was 1:1·04.     

Juvenile development and growth patterns in the mud crab Eurytium limosum (Say, 1818) (Decapoda,Brachyura, Xanthidae) under laboratory conditions

The post‐larval development of the mud crab Eurytium limosum was studied under laboratory conditions by using the offspring of ovigerous females collected at the Comprido River mangrove, SP, Brazil. The first crab stage is fully described and the juvenile development, until crab stage 10, is examined with emphasis on morphological change, sexual differentiation and growth patterns. The carapace of the first crab stage is nearly square as observed in other xanthids, becoming similar to adults only at stage 15. The sexes can be distinguished from stage four, based on the number of pleopods and their morphology. While the intermoult period increases, the moult percentage decreases at each stage. The abdominal allometric growth is sex‐dependent, with males showing a negative (b?=?0.71) and females an isometric (b?=?0.95) relative growth pattern. Male gonopods undergo a positive allometric growth, and their shape changes remarkably until sexual maturity. The cheliped dentition can be observed after stage 4. Regardless of sex, most crabs have a molariform right cheliped, which is thought to aid the handling of asymmetric prey such as gastropods.