Feeding and bioturbation effects of the sand dollar Peronella lesueuri (L. Agassiz, 1841) (Echinodermata) on microphytobenthos and sediment fluxes

Respiration and excretion rates of a key bioturbating species, the sand dollar Peronella lesueuri, were measured in mesocosms at three different temperatures. Benthic oxygen and nutrient fluxes were additionally measured at winter and summer temperatures to assess the impact of P. lesueuri on ecosystem processes. Oxygen consumption by sand dollars increased significantly with wet weight at all three temperatures 16, 19, and 23 °C. Ammonia release also increased with body weight. The weight vs. oxygen uptake relationship was similar at 19 and 23 °C but oxygen uptake was significantly reduced at the lower exposure temperature. The bioturbation caused by sand dollar P. lesueuri reduced the photosynthetic rate of the microphytobenthos (MPBs) but had a much smaller and less obvious effect on nutrient fluxes across the sediment–water interface.     

Annual reproductive cycle and growth of the pen shell Atrina maura (Pterioidea: Pinnidae) on sand-bottom culture in the Ensenada Pabellones lagoon system,Gulf of California,Mexico

Abstract

The reproductive cycle and growth of the pen shell, Atrina maura, which was cultured in the Ensenada Pabellones lagoon system, Gulf of California, from March 2008 to March 2009, is described in this article. Histological techniques and the condition index were used to determine its reproductive condition. The sex ratio was 0.57 females:1.72 males within the population studied. There were no differences (χ², p < 0.05) in shell length (SL) between males and females. The mean length of the sampled specimens ranged between 50.99 ± 4.86 mm and 218.16 ± 8.87 mm. The histological results confirmed that A. maura is a gonochoristic organism that presents synchronic development of the gonads. The maturity and spawning phases were observed throughout the study period, with the exception of March and May 2008. The frequency of the gonad development stages obtained per month suggests that this species reproduced two times annually, with one important reproductive period from June to September, a minor reproductive period from November to February, and two resting periods as follows: July to August and January to February 2009.     

Reproductive biology of <Emphasis Type="Italic">Astyanax lacustris</Emphasis> (Characiformes: Characidae) in the southern Pantanal floodplain,upper Paraguay River basin,Brazil

We studied the reproductive biology of Astyanax lacustris in the southern Pantanal, Brazil. A total of 382 fish were analyzed from February 2009 to January 2011. The sex ratio differed significantly from 1:1, with a larger proportion of females (χ² = 27.24; p < 0.001). Females achieve higher standard length than males (mean 72.30 mm and 56.51 mm, respectively), and possess negative allometric growth while males have positive allometric growth. Size at first maturation did not differ between sexes. The greatest reproductive activity occurred during the rainy season, when temperatures were highest (November to February). Total fecundity was significantly correlated with standard length (r_s = 0.74; p = 0.01), and spawn type was total. Then, the life history traits of A. lacustris are adjusted to seasonal variation in the Southern Pantanal.     

Biomass of extramatrical ectomycorrhizal mycelium and fine roots in a young Norway spruce stand — a study using ingrowth bags with different substrates

Background and aims

The partitioning of below ground carbon inputs into roots and extramatrical ectomycorrhizal mycelium (ECM) is crucial for the C cycle in forest soils. Here we studied simultaneously the newly grown biomass of ECM and fine roots in a young Norway spruce stand.

Methods

Ingrowth mesh bags of 16 cm diameter and 12 cm height were placed in the upper soil and left for 12 to 16 months. The 2 mm mesh size allowed the ingrowth of fungal hyphae and roots whereas a 45 μm mesh size allowed only the ingrowth of hyphae. The mesh bags were filled with either EA horizon soil, pure quartz sand or crushed granite. Controls without any ingrowth were established for each substrate by solid tubes (2010) and by 1 μm mesh bags (2011). The fungal biomass in the substrates was estimated by the PLFA 18:2ω6,9 and ECM biomass was calculated as difference between fungal biomass in mesh bags and controls.

Results

The maximum ECM biomass was 438 kg ha^?1 in October 2010 in 2 mm mesh bags with EA substrate, and the minimum was close to zero in 2011 in 45 μm mesh bags with quartz sand. The high P content of the crushed granite did not influence the ECM biomass. Fine root biomass reached a maximum of 2,343 kg ha^?1 in October 2010 in mesh bags with quartz sand after 16 months exposure. In quartz sand and crushed granite, ECM biomass correlated positively with fine root biomass and the number of root tips, and negatively with specific root length.

Conclusion

The ratio of ECM biomass/fine root biomass in October ranged from 0.1 to 0.3 in quartz sand and crushed granite, but from 0.7 to 1.8 in the EA substrate. The results for the EA substrate suggest a large C flux to ECM under field conditions.     

Reproductive ecology of the glacier lanternfish Benthosema glaciale

Myctophids play a key role in the transfer of energy in pelagic food webs, linking zooplankton to higher trophic levels. Data are presented, for the first time for the glacier lanternfish (Benthosema glaciale), on maturity ogives, size-at-maturity and reproductive strategy in terms of ovarian organization and fecundity type in two contrasting environments: North Atlantic and Mediterranean. We analysed 292 females collected in Flemish Cap during early summer 2009 and 2011 and off the Balearic Islands during late autumn 2009 and early summer 2010. The spawning season differed between areas. Size at 50% maturity in Flemish Cap was 47.6 and 49.1 mm in 2009 and 2011, respectively, but significantly smaller, 24.5 mm, in the Balearic sea. B. glaciale is a batch spawner with asynchronous ovarian development and indeterminate fecundity. Batch fecundity showed significant relationships with length and weight, although average relative batch fecundity was low (1031 ± 396 oocytes/gram). We compared two staining techniques: Hematoxylin–eosin and PAS–hematoxylin–metanil yellow with the latter being more useful to detect mature females and spawning indicators in regressing and regenerating females. Our results contribute to a better understanding of the reproductive potential and ecological role of this species, the most abundant myctophid in the northern Atlantic.     

Population structure and reproduction of the longtail grass shrimp Urocaris longicaudata (Decapoda,Caridea, Pontoniinae) in Laguna de Términos,SW Gulf of Mexico

The purpose of this study was to describe the population structure and some reproductive traits of Urocaris longicaudata collected in Laguna de Términos, Campeche, Mexico in October and December 2009, and February and April 2010. A total of 2977 specimens were collected of which 1596 were females (including 276 ovigerous) and 1381 were males. Females were larger than males (2.03 ± 0.63 vs. 1.97 ± 0.44 mm carapace length (CL), respectively). The overall sex-ratio differed significantly from 1:1. The reproductive period was apparently continuous, with most ovigerous females recorded from December 2009 to April 2010. The estimated size at sexual maturity in females was 2.90 ± 0.64 mm CL. A significant and positive linear relationship between CL and realised fecundity was estimated. The number of embryos ranged from 33 to 320. The average volume of newly spawned embryos was 0.038 ± 0.009 mm³ and that of those near hatching was 0.062 ± 0.012 mm³, representing a 63.15% increase throughout embryogenesis. The females lost on average 27.6% of the initially produced embryos during the incubation period, which favoured the survival of the remaining embryos. This is the first report on any biological trait of U. longicaudata along the southwestern Gulf of Mexico.     

The reproductive ecology of the invasive Asian paddle crab,Charybdis japonica (Brachyura: Portunidae), in northeastern New Zealand

The Asian paddle crab, Charybdis japonica, native to the northwest Pacific, is an invasive species that has established populations within northeastern New Zealand. Here, we provide a detailed examination of C. japonica's reproductive seasonality and gametogenesis, sizes at physiological maturity, and sex ratios outside its native range. Trapping in the Weiti River Estuary, Whangaparoa (36°38.4′S, 174°43.6′E) from February 2010 to May 2012 indicated a male‐biased population. Reproductive seasonality largely depended on female condition, since males contained ripe spermatozoa year‐round. Female gametogenesis began during late autumn, with oocyte development occurring throughout winter to early spring. Based on the presence of mature gametes during late winter and the appearance of gravid females in early November, mating began during early spring, with spawning in mid‐spring. Spawning coincided with a large drop in the gonad index, and occurred between sea surface temperatures of 17–22°C and 11.75–13.5 h day length. Females remained reproductive for up to 5 months of the year. Histological observation suggested that CW50 (the carapace width at which 50% of the population is mature) for females was 46.39 mm, while CW50 for males could not be determined due to a paucity of immature males. Histological analysis also suggested that females of C. japonica could produce store sperm and multiple broods annually.     

Gonad morphology and reproductive cycle of the mangrove oyster Crassostrea brasiliana (Lamarck, 1819) in the baía de Guaratuba,Paraná, Brazil

This study aimed to describe the gonadal histology and the reproductive cycle of Crassostrea brasiliana in the mangroves of Guaratuba Bay in southern Brazil. Adults were collected monthly from January 2010 to April 2011 from three sampling sites in intertidal oyster beds. The animals were evaluated using biometric and histological analyses of the gonads. The gonadal tissue samples were processed according to the standard histological procedures, and permanent slides were prepared using Harris' haematoxylin and eosin. The oysters were identified at the species level using a molecular protocol. Females (69%) predominated over males (26%), with 4% indeterminate and 1% hermaphroditic. Mature females were more prevalent in February, March and December 2010 and in March 2011. Mature males were more prevalent in February and April 2010 and in March 2011. The presence of hermaphroditic individuals was sporadic, and oysters in immature stages or sexual repose were observed in only a few collections between the months of May and October 2010. The reproduction of C. brasiliana in Guaratuba Bay occurs intermittently, but with greater intensity during the summer, with a larger number of females produced.     

Reproduction and developmental pathways of Red Sea Xeniidae (Octocorallia,Alcyonacea)

This work on Red Sea alcyonaceans describes the reproductive patterns of 21 xeniid species. Gonochorism is the commonest sexual mode but simultaneous hermaphroditism was recorded in 4 species and brooding of planulae was observed in 15 species. The reproductive patterns of Xenia umbellata and Heteroxenia fuscescens were examined. X. umbellata exhibits seasonal spermatogenesis, continuous oogenesis and a 7 month period of planulation each year. H. fuscescens has continuous gametogenesis, and planulation occurs throughout the year, lacking any lunar pattern. The prolonged breeding season of H. fuscescens reflects intrapopulation asynchrony in larval development and subsequent maturation. Xeniids possess structurally similar gonads, but adopt diverse reproductive and developmental pathways.     

Population structure,recruitment, and mortality of the freshwater crab Dilocarcinus pagei Stimpson, 1861 (Brachyura,Trichodactylidae) in Southeastern Brazil

Freshwater crabs of the family Trichodactylidae are widely distributed in major river basins of the South American continent. The population structure of one species, Dilocarcinus pagei, was analyzed in an artificial reservoir in Southeastern Brazil, recording data on the sex ratio, recruitment, and mortality. A total of 1339 crabs were collected and included 804 males and 535 females (3 ovigerous and 4 with hatchlings); the sex ratio was 1:0.61 (males: females). Two modes of male and female carapace width (CW) were recorded, with means of 14.4 mm (n = 407) and 38.9 mm (n = 394) for males and 17.9 mm CW (n = 269) and 39.2 mm (n = 267) for females. The mean size of males (CW = 26.6 ± 13.8 mm) was significantly larger than that of females (CW = 28.5 ± 12.8 mm). The data indicated that recruitment occurs in summer (January–March), with the reproductive period in spring (October–December), periods with the highest rainfall and temperature values in the region. Reproduction leads to the death of the parents, influencing the sex ratio, which oscillates mainly during the reproductive period.     

Reproductive biology of Coilia mystus (Linnaeus) from the Yangtze Estuary,China: responses to overexploitation

Fishery harvest of Coilia mystus in the Yangtze Estuary has declined dramatically since the late 1990s. A full understanding of the reproductive biology of this species is essential for effective management of the population. A total of 1072 females of C. mystus collected from the Yangtze Estuary area between May 2006 and September 2007 were analyzed to reveal the general reproductive biology of the population. Females with increased gonadosomatic index (GSI) and gonads developed to stages IV and V occurred mainly from March through August, indicating a major spawning season in this period; there were also a few females with increased GSI and developed gonads observed in November and January. Absolute fecundity (AF) ranged from 3093 to 36 786; and increased with both body weight (BW) and age. The relationship of AF to BW was fitted to a linear function AF = 924.72 × BW?414.17 (r² = 0.82, n = 134, P < 0.05). Relative fecundity was 871 eggs per gram. Oocyte diameter (OD) of mature females ranged from 0.55 to 0.90 mm with a mean (±SD) of 0.71 ± 0.05 mm (n = 3927), independent of BW. The frequency distribution of OD showed a single mode and histological examination demonstrated that the development of oocytes was synchronous within an ovary, suggesting that C. mystus is a single spawner. Compared to previous studies, females in this study tended to produce more but smaller eggs. This increased fecundity may represent biological compensation for the decline in abundance of the population due to overexploitation.     

Spatial variation in the annual reproductive cycle of Turbo (Batillus) cornutus (Gastropoda: Trochidae) at Jeju Island,Korea

The annual reproductive cycle of the top shell Turbo cornutus from Jeju Island was investigated in two populations using histology. In the northern population, gametogenesis commenced in January as the surface water temperature reached 14?°C, while in the southern population gametogenesis began a month earlier, as the water temperature remained at 17?°C. Ripe top shells first appeared in June and spawning continued from June to October when water temperatures were between 20 and 24?°C. Histology indicated that the spawning period of the southern population was a month earlier and lasted longer (June–October) than in the northern population (July–September). The percentage gonad area of animals in the southern population in March and April was significantly higher than in the northern population (p?相似文献   

Restoration action and species response: oviposition habits of Plebejus icarioides fenderi (Lepidoptera: Lycaenidae) across a restoration chronosequence in the Willamette Valley, Oregon, USA

Habitat restoration is critical to the conservation of rare species. However, restoration efforts often proceed without knowledge of their effects on these species. We investigated the reproductive response of federally endangered Fender’s blue butterfly (Plebejus icarioides fenderi) to prairie restoration in Willamette Valley, Oregon, USA. In 2009 and 2010, we quantified availability of larval host plant, Kincaid’s lupine (Lupinus oreganus), and butterfly oviposition in three restored areas (1–10 years old) and adjacent intact habitat. Oviposition measures in restored areas reached or exceeded intact habitat (0.1 eggs/leaf of host plant and 12 % of time ovipositing) within five years post-restoration. However, none of the restorations provided an equivalent host plant density to intact areas (55 leaves/m²). The different response time of host plants and butterflies to restoration highlights the importance of monitoring both vegetation and oviposition over an ecologically relevant timescale (at least 10 years). For imperiled species, quantifying reproductive response to restoration is critical for adaptive management and successful conservation of the species which restoration efforts are intended to benefit.     

Food availability and sex reversal in Mytella charruana,an introduced bivalve in the southeastern United States

We studied the reproductive biology of Mytella charruana to determine the potential reproductive success of this newly introduced bivalve species from Central/South America. We analyzed gonad morphology, gametogenesis, and the sex ratios of introduced populations throughout a 12 month period. In the non‐native habitat M. charruana shows the same strategy of gametogenesis that had been observed in its native environment, which is an opportunistic type of gonadal cycle with gametes produced throughout the year. Instead, the spawning period of M. charruana along the southeastern US coast is extended compared to that found in the native environment. We determined the minimum size (shell length) of sexually reproductive mussels to be 1.25 cm. Interestingly, throughout the year the population samples were typically composed of a higher proportion of females. The female to male sex ratio varied within a wide range from 1:0 to 1:3.3. Upon this discovery we tested the effects of food availability on the gametogenesis of adult animals. The sex ratio of mussels collected from different locations and maintained in the laboratory with or without food changed toward a male‐bias under starvation conditions within a month. This is the first study directly showing that food availability can trigger sex reversal in an adult bivalve. According to our data this mussel species will likely continue to spread along the east coast of the US. Moreover, M. charruana may prove to be a model organism in the study of alternative sexuality in bivalves. Mol. Reprod. Dev. 77: 222–230, 2010. © 2009 Wiley‐Liss, Inc.     

Seasonality and species composition of Peristenus (Hymenoptera: Braconidae) species,and Lygus (Hemiptera: Miridae) species parasitism in southern Alberta,Canada

We report a long-term survey summarising the seasonal variation in species composition of Peristenus species, and their levels of parasitism in an assemblage of Lygus spp., over more than 10 years in southern Alberta in western Canada. Plants sampled include alfalfa (Medicago sativa L.), canola (Brassica napus L.), and stands of different weed and grass species commonly found on crop field edges. Three native Peristenus species (Peristenus dayi, Peristenus mellipes, and Peristenus howardi) were recorded in 2003–2011 and 2013–2015. In laboratory trials, P. mellipes emerged 13 days earlier than P. howardi. Degree-days for field-collected individuals suggested a sequential occurrence during the growing season: P. dayi appears early in the season, followed by P. mellipes, and later on by P. howardi. Studies of species composition and phenology of native parasitoids of insect pests provide valuable baseline information when considering introduction of exotic agents, and contribute to the management and improvement of conservation biological control by endemic natural enemies in agricultural systems.     

The Resistance Analysis of Ureaplasma urealyticum and Mycoplasma hominis in Female Reproductive Tract Specimens

The aim of this study was to analyze the drug resistance of Ureaplasma urealyticum (Uu) and Mycoplasma hominis (Mh) in female reproductive track from 2007 to 2011 in Hangzhou. Antibiotics sensitivity test in Mycoplasma, which was isolated in clinics from 2007 to 2011 were analyzed retrospectively. The detection of Mycoplasma during 2007–2011 was 20,146 (54.37 %), of which the single infection rate of Uu was 42.08 %, of Mh 1.26 %, and of Uu+Mh was 11.02 %. The drug resistance rate of Uu was increased significantly in ofloxacin in 2007 (41.80 %), 2008 (45.94 %), 2009 (46.07 %), 2010 (50.36 %), and 2011 (53.22 %) (P < 0.05). The resistance rate to ciprofloxacin was significantly increased in 2007 (67.15 %), 2008 (67.44 %), 2009 (73.00 %), 2010 (75.28 %), and 2011 (75.28 %) (P < 0.05). Exceptionally, the resistance rates of the other antibiotics were low. The drug resistance rate of Uu was significantly increased with quinolones at increasing tendency. It is necessary to monitor the local drug resistance rate of Uu regularly to provide reasonable guidelines in clinics.     

Gonad characterization and reproductive seasonality in Siphonaria lessonii (Gastropoda: Heterobranchia) from the southwestern Atlantic Ocean

Histological characterization of the hermaphroditic gonad (HG) and seasonality of gametogenesis were investigated in a population of Siphonaria lessonii from the coast of Buenos Aires Province (37°16′S, 56°58′W). Monthly analysis of the frequency of gametogenic stages, as well as the number and mean size of oocytes, were used to determine reproductive events over a 2‐year period (June 2012–May 2014). Female and male gametes were observed simultaneously within acini of adult individuals and continuously throughout the period studied. Oogenesis commenced in the beginning of austral autumn, with gonads characterized mainly by proliferation of female cells. From this moment, oocytes gradually increased in number and area until spring, when a large number of individuals were found in the evacuation stage. The same trend was observed from early gonad maturation to advanced stages, indicating that gonad development was closely related to the frequency of oocyte stages and to the area (size) of oocytes. Spermatogenesis was also observed as a continuous process throughout the year, although spent acini were more frequent from November until February. Reproductive seasonality and gametogenesis were associated with changes in temperature and day length.     

Spindle-E is essential for gametogenesis in the silkworm,Bombyx mori

As a defense mechanism against transposable elements, the PIWI-interacting RNA (piRNA) pathway maintains genomic integrity and ensures proper gametogenesis in gonads. Numerous factors are orchestrated to ensure normal operation of the piRNA pathway. Spindle-E (Spn-E) gene was one of the first genes shown to participate in the piRNA pathway. In this study, we performed functional analysis of Spn-E in the model lepidopteran insect, Bombyx mori. Unlike the germline-specific expression pattern observed in Drosophila and mouse, BmSpn-E was ubiquitously expressed in all tissues tested, and it was highly expressed in gonads. Immunofluorescent staining showed that BmSpn-E was localized in both germ cells and somatic cells in ovary and was expressed in spermatocytes in testis. We used a binary transgenic CRISPR/Cas9 system to construct BmSpn-E mutants. Loss of BmSpn-E expression caused derepression of transposons in gonads. We also found that mutant gonads were much smaller than wild-type gonads and that the number of germ cells was considerably lower in mutant gonads. Quantitative real-time PCR analysis and TUNEL staining revealed that apoptosis was greatly enhanced in mutant gonads. Further, we found that the BmSpn-E mutation impacted gonadal development and gametogenesis at the early larval stage. In summary, our data provided the first evidence that BmSpn-E plays vital roles in gonadal development and gametogenesis in B. mori.     

Growth and reproduction of the north-eastern Atlantic keystone species <Emphasis Type="Italic">Patella aspera</Emphasis> (Mollusca: Patellogastropoda)

The growth and reproductive biology of the limpet Patella aspera were studied in the north-eastern Atlantic, Madeira archipelago, to enhance the knowledge concerning biological parameters and population dynamics of this species. This study comprised the estimation of growth rates, sexual maturity, reproduction, recruitment patterns, mortality coefficients and the exploitation rate, and yield-per-recruit (Y/R) based on monthly shell-length frequency data. A total of 16,941 specimens were sampled from January to December 2015. The relative growth pattern exhibited a negative allometric nature of growth for both sexes. The estimated von Bertalanffy growth parameters showed an asymptotic length of 84.15 mm for females and 80.51 mm for males with a growth coefficient of 0.36 and 0.32 year^?1 respectively. P. aspera in this geographical area is a moderately long-lived limpet with a predominance of specimens younger than 3 years old. This species is a winter breeder with a reproductive cycle encompassing three main periods namely development, spawning and resting with a synchronous gametogenesis for both sexes. Gonadal development lasts from October to December, spawning likely occurs from January until April and resting occurs from May to September. The mean size at sexual maturity was determined as 41.78 mm for females and 38.29 mm for males and the length at first capture as 42.62 mm. The recruitment pattern was continuous throughout the year with a major peak identified in March. The natural, fishing and total mortalities were similar between sexes, with fishing mortality exerting greatest pressure on this resource. However, yield-per-recruit analysis showed that the stock of P. aspera, in the study area, is exploited at levels below the fishing mortality that returns maximum sustainable yield. This study revealed that currently the stock of P. aspera is under-exploited, nonetheless due to it’s slow growth and long life, continuous monitoring and the enforcement of the existing harvest regulations must be accomplished if future over-exploitation is to be avoided. Further genetic studies are necessary to establish connectivity of the populations and improve present conservation strategies.