Histopathology of Pleuronectes platessa L. from Aber Wrac'h and Aber Benoit, Brittany, France: long-term effects of the Amoco Cadiz crude oil spill

Abstract. Organ samples were collected from plaice, Pleuronectes platessa L., captured in the highly oiled Aber Wrac'h and Aber Benoit at five intervals during the period 1978-1980, following the Amoco Cadiz crude oil spill. Reference plaice were obtained along the western and southern coasts of Brittany. Tissue samples were fixed, processed and stained by routine histologic procedures for qualitative and quantitative histopathological examination. The predominant lesions and conditions which characterized fish from the oiled estuaries were: fin and tail necrosis, hyperplasia and hypertrophy of gill lamellar mucous cells, gastric gland degeneration, decreased hepatocellular vacuolation (lipid), increased concentration of hepatic macrophage centres and lateral trunk muscle fibre degeneration. Dilation of Bowman's space, glomerular hypertrophy and abdominal muscle fibre degeneration were pronounced at the last sampling interval. Other types of lesions were seen at a lower frequency: hyperplasia and fusion of gill lamellar epithelium, telangiectasis of gill capillaries, hepatopancreatic degeneration and hepatic necrosis. Fish muscle and liver collected for biochemical analysis to detect the presence or absence of petroleum hydrocarbons were negative for Amoco Cadiz oil fractions. At the same time oysters, Crassostrea gigas Thunberg, collected from the oiled estuaries throughout the study period, showed high levels of Amoco Cadiz oil fractions. These data, along with the type and frequency of lesions observed, suggested that the plaice had been chronically-exposed to petroleum hydrocarbons of Amoco Cadiz origin. Some relief from chronic pollutant exposure was indicated by a decrease in gill mucous cell concentration at the last sampling interval. An increase in abdominal muscle fibre degeneration and an increase in the frequency of dilation of Bowman's space with glomerular hypertrophy at the last sampling interval suggested a latent response to the polluting agent.     

Confirmation of ovarian homogeneity in post-vitellogenic cultured white sturgeon,Acipenser transmontanus

Assessing stage of oocyte maturity in female sturgeon by calculating oocyte polarization index (PI) is a necessary tool for both conservation propagation managers and caviar producers to know when to hormonally induce spawning. We tested the assumption that sampling ovarian follicles from one section of one ovary is sufficient for calculating an oocyte PI representative of oocyte maturity for an individual animal. Short-wavelength near-infrared spectroscopy (SW-NIR) scans were performed on three positions per ovary for five fish prior to caviar harvest. Samples of ovarian follicles were subsequently taken from the exact location of the SW-NIR scans for calculation of oocyte PI and follicle diameter. Oocyte PI was statistically different though not biologically relevant within an ovary and between ovaries in four of five fish. Follicle diameter was statistically different but not biologically relevant within an ovary in three of five fish. There were no differences in follicle diameter between ovaries. No statistical differences were observed between SW-NIR spectra collected at different locations within an ovary or between ovaries. These results emphasize the importance of utilizing both oocyte PI measurement and progesterone-induced oocyte maturation assays while deciding when to hormonally induce spawning in sturgeon females.     

Polar and neutral lipid composition of the gonads and serum of the plaice,Pleuronectes platessa L.

The individual polar and neutral lipids of plaice (Pleuronectes platessa L.) ovaries, testes and serum were determined, just before spawning, in February 1984 and March 1985. Serum was also assayed in June and September 1984. Phosphatidylcholine (PC) was found to be the major polar lipid in both male and female plaice serum throughout the year and in the ovaries. The testes, however, contained almost equal amounts of PC and phosphatidylethanolamine. The polar lipid levels in plaice gonads, expressed as a percentage of the total lipid present, were higher in the ovaries than in the testes, but in male plaice serum, the percentage of polar lipid was consistently higher than in the female. In plaice testes, 86% of the total neutral lipid occurred as cholesterol, but this represented only 49% of the total neutral lipid in the ovaries, with triacylglycerol as the other major ovarian neutral lipid.     

Accumulation of a bitter amino acid,pulcherrimine, in sea urchin ovaries and its relevance to the annual reproductive cycle

Hemicentrotus pulcherrimus in the Tohoku area is not utilized as a fishery product because the ovaries have a bitter taste almost all year. To discover the cause, we compared the annual reproductive cycles and ovarian accumulation of a bitter amino acid, pulcherrimine, in H. pulcherrimus collected at Mikuni (Fukui Prefecture), where it is fished in summer, and Iwaki (Fukushima Prefecture), where it is not utilized. At both sites, pulcherrimine increased in maturing ovaries as oogenesis proceeded from autumn to winter, decreased after spawning in spring, but remained in spent and immature ovaries for a few months. In Mikuni, pulcherrimine was scarcely detected in the ovaries for several months in summer. However, in Iwaki, late spawning delayed the disappearance of pulcherrimine in summer, and early initiation of oogenesis advanced the restart of pulcherrimine accumulation in autumn compared to Mikuni. Consequently, the period when the ovaries were palatable because of the absence of pulcherrimine during summer was short in Iwaki. The major cause of such short-term palatability could be the lower seawater temperature in the Tohoku area. Furthermore, pulcherrimine was never detected in other sea urchins, although a bitter taste was found in the mature ovaries of some species.

     

Maturation and reproductive cycle of female armorhead <Emphasis Type="Italic">Pseudopentaceros wheeleri</Emphasis> from the southern Emperor—northern Hawaiian Ridge Seamounts

ABSTRACT:   The stage of ovarian development and annual reproductive cycle of female armorhead Pseudopentaceros wheeleri collected from seamounts of the southern Emperor–northern Hawaiian Ridge in 1993 and 1995–1996 was investigated through use of the gonadal somatic index ( GSI ) and ovarian histology. The stages of oocyte development were classified into eight developmental stages (perinucleolus, cortical alveolus, oil droplet, early yolk globule, late yolk globule, migratory nucleolus, prematuration, and maturation) based on histological characteristics. Oocytes of different size and developmental stage were present within ovaries during the spawning season. Oocyte development appears to be asynchronous and armorhead apparently spawn several times during the spawning season. The stage of the most developed oocyte was used to classify the stage of ovarian maturation. The GSI increased gradually with ovarian development. Oocytes in the perinucleolus, cortical alveolus, and oil droplet stages were present in ovaries throughout the year. Early and late yolk globule stages appeared during August–September indicating that yolk formation begins during late summer. The migratory nucleolus through maturation stages were detected during November–January. Post ovulatory follicles were present during November–March, and GSI values rapidly decreased in February. Results indicate that spawning occurs during November–February and peaks during December–January.     

Ovarian maturation stages of the mud crab Scylla serrata

Ovarian maturation in adult wild‐sourced and pond‐grown Scylla serrata (Forsskål) was determined based on gross morphology and histological appearance. There were no significant differences noted in the histological features of both wild and pond‐reared S. serrata females. Ovarian maturation was classified into five stages: immature, early maturing, late maturing, fully mature and spent. The immature ovaries are thin and translucent to off white and contain oogonia, primary oocytes with large nuclei. The follicle cells were found around the periphery of the lobes and an area among groups of oogonia and oocytes. The follicle cells gradually enclosed the oocytes. The early‐maturing ovaries were yellow and small yolk globules started to appear in larger oocytes. In late‐maturing ovaries, the colour became light orange and lobules were apparent. Yolk globules occurred in the cytoplasm with larger globular inclusions towards the periphery, while follicle cells were hardly recognizable. Fully mature ovaries were orange to deep orange and had swollen lobules. Large yolk globules were apparent in the entire cytoplasm. Follicle cells were hardly seen. Spent ovaries were similar to the early‐maturing and late‐maturing stage in partially spawned females. The ovarian development was correlated closely to the gonadosomatic index, oocyte diameter, and ovarian histology. The classification of ovarian maturation provides baseline information for further studies on reproductive biology. Likewise, the information provides a guide for broodstock management in the hatchery.     

Fundulus heteroclitus Gonadotropin(s) 2. Year-round husbandry of animals with active pituitaries and responsive follicles

Mummichogs (Fundulus heteroclitus) were exposed to various regimens of temperature and photoperiod in order to develop a routine husbandry procedure so as to have throughout the year a population of reproductively healthy fish with a good quantity and quality of prematuration follicles (1.2–1.5 mm) suitable for carrying out homologous bioassays ofF. heteroclitus gonadotropin. During the fall and winter months, wild fish in the field all had regressed ovaries (gonadosomatic index <1). On the other hand, laboratory-maintained fish, with or without cold temperature (15°C) and short photoperiod (10 h light/day) pretreatment, generally had sexually mature ovaries (GSI>10) when maintained on a warm temperature (25°C) and long photoperiod (14 h light) protocol. Ovarian follicles retrieved from laboratory fish were responsive toF. heteroclitus pituitary extract stimulation, and underwent germinal vesicle breakdown normallyin vitro. Hence these ovarian follicles served well as a bioassay forF. heteroclitus gonadotropin even outside of the normal breeding season. The pituitary glands retrieved from laboratory fish in winter also retained high gonadotropic potencies, in terms of maturational and steroidogenic activities. Our results thus demonstrated that active gametogenesis in laboratory-maintained fish can be extended five months beyond the end of the normal breeding season. Apparently,F. heteroclitus in Florida is potentially a continuous breeder when under favorable conditions, but has a reproductive quiescent period imposed upon it by some environmental stressor(s). Although the design of the present experiments did not determine the relative importance of nutritional factors, temperature, and photoperiod on the annual reproductive cycle ofF. heteroclitus, there are indications that diatary factors may play a much more dominant role in the reproductive cycle than previously recognized.     

The reproductive cycle of the ‘blunt’ sea urchin

The reproductive cycle of the blunt sea urchin, Sphaerechinus granularis (Lamarck), was studied in the Bay of Brest, West Brittany, from monthly samples by examining seasonal changes in gonadal index, in the stages of gonad development and in oocyte diameters. This echinoid exhibited an annual cycle of gonadal growth, with a short breeding season occurring in May and June, and a decrease in gonadal index during the winter attributed to the use of nutrient resources. Histological examinations defined long mature stages during autumn, winter and early spring, where the vitellogenic oocytes accumulated in the lumen of the gonad. Changes in oocyte diameters showed a short pre-spawning period in April and May. The brief breeding season was followed by rapid post-spawning recovery and gonad growing stages during the summer, where the gonads mainly grew through the development of nutritive tissue. The features of this reproductive cycle show that the species can be commercially exploited and these results are used to make recommendations in terms of the management of S. granularis fisheries in Brittany. The influence of temperature on the initiation of spawning was noted again. This exogenous factor could be monitored to improve gonad production and availability of mature gametes in mariculture projects. © Rapid Science Ltd. 1998     

Oogenesis and lipids in gonad and liver of daubed shanny (Leptoclinus maculatus) females from Svalbard waters

Oocyte and liver histomorphology of the daubed shanny (Leptoclinus maculatus) from Isfjorden and Kongsfjorden in Svalbard were investigated during three Arctic seasons: summer (July), autumn (October) and winter (April). Three oocyte developmental phases were observed: primary growth phase, secondary growth phase and maturation phase. We observed four different developmental stages: (1) perinucleolus stage with cortical alveolus formation, (2) lipid droplets formation, (3) vitellogenesis stage and (4) maturation. Late maturation stage of oocytes in the ovaries was from the autumn season. Females accumulated lipids in liver (up to 35.2?% dw) and deposited large amounts of lipids into gonads (up to 52.2?% dw) during maturation. Lipid classes in female gonads changed seasonally, with relative increase in cholesterol during summer and depletion of storage lipids (triacylglycerols and wax esters/cholesterol esters) during the winter. Lipid composition in liver changed during oocyte development and spawning, as neutral lipids were transferred to developing oocytes during summer to autumn. During winter, storage lipids were depleted during starvation. Based on the increase in gonadosomatic index (GSI) with length and observed maturation stages, females seem to mature at a length of about 125-130?mm. The GSI and hepatosomatic index of large females sampled in autumn (September-October) were significantly higher than for females in late winter (April) and spring (May). These results indicate that spawning takes place during winter in Isfjorden and that energy reserves stored in the liver are utilized by females during gonadal development and reproduction.     

Reproductive cycle of the Amazonian planktivorous catfish Hypophthalmus marginatus (Siluriformes,Pimelodidae)

We evaluated the annual process of oocyte and ovarian development of the planktivorous Amazonian catfish, the mapará (Hypophthalmus marginatus), aiming to support captive reproduction for domestication. A total of 149 females were captured from the Tocantins River at the Tucuruí Dam (3°49'55"S, 49°39'9"W) in 13 sampling events. For each individual, we evaluated ovary histology and plasma steroid concentrations. Two annual reproductive cycles, with similar characteristics, including a long period of rest, a short vitellogenic stage and a well‐defined spawning season from November to March, were described. A 17β‐estradiol (E₂) rise and a 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (DHP) peak were associated with vitellogenesis and spawning season, respectively, in the first cycle but not in the second reproductive cycle. In conclusion, the studied species presents a reproductive cycle similar to that of other migratory total spawners; however, unusually for this group of fish, there were three (but not two) batches of vitellogenic oocytes in “in maturation” and “mature” stage ovaries, pointing to the possibility of more than one spawn during the spawning season.     

Reproductive cycle,sexual maturity and diel-reproductive periodicity of white croaker,Pennahia argentata (Sciaenidae), in Ariake Sound,Japan

The white croaker, Pennahia argentata (Houttuyn), is abundant in demersal fish assemblages in Ariake Sound and is a commercially important species. The reproductive biology of white croaker was studied by measurement of gonadosomatic indices (GSI) and histological examination of ovaries. Ovaries were classified into one of five maturity stages based on histological data: (1) immature/resting stage; (2) developing stage; (3) maturing stage; (4) ripe/spawning stage; (5) spent stage. The spawning season lasts from April to September but most activity is observed from May to August. Age at sexual maturity was assumed to be 1 year. Postovulatory follicles coexisted with yolk stage oocytes in histological sections of ovaries indicating that white croaker is a multiple spawner, spawning more than once in a single spawning season. Judging from the diel changes in the proportion of females with ovaries containing postovulatory follicles and oocytes at maturation stage, most females spawned in the evening between 19:00 and 21:30 h.     

Atlantic Salmon (Salmo salar L.) in Brittany and Lower-Normandy: Preliminary Observations on the General Characteristics of Adults

This paper presents some characteristics (length, weight and age) of adult Atlantic salmon in rivers of Brittany. The data were derived from 1,578 fish caught mainly by rod and line; the remainder being from net catches in estuaries and small samples taken outside the fishing season. The bulk of the fish spent 1 or 2 years in freshwater before smoltifying. Those fish becoming smolts at the end of 1 year were the most numerous (54%). The majority of the fish sampled were spring fish (82.4%). Very few summer fish were identified and those found were mainly grilse. The high proportion of spring fish in the sample is due to the high proportion of rod-caught fish. Probably a complete census over the year would show a larger proportion of grilse and summer fish as these are not subject to heavy rod-fishing the season being closed at the beginning of June. The relationship between sea age and river age and the influence of freshwater life upon the sea life were tested in four rivers. It seems probable that sea life depends chiefly on the river and the year of smoltification rather than on the freshwater stage. The biometric characteristics of Brittany salmon were compared with data from some foreign rivers. The angling exploitation of the spring Atlantic salmon in Brittany and the lack of data about summer migrations are discussed in regard to the future of this stock.     

Annual and lunar-synchronized ovarian activity in two rabbitfish species in the Chuuk lagoon, Micronesia

ABSTRACT:   This study examined the annual and the lunar cycles of ovarian activity in the forktail rabbitfish Siganus argenteus (Quoy & Gaimard, 1825) and the spiny rabbitfish Siganus spinus (Linnaeus, 1758), which were collected from the Chuuk lagoon, Federated States of Micronesia. Gonadosomatic index (GSI) increased in May and June for S. argenteus . For S. spinus , GSI increased in March, and from July to September. During these periods, the ovaries of these species contained oocytes at the tertiary yolk stage or the maturation stage, suggesting that these months are the reproductive season of the two species. During the reproductive season, weekly collection of the fish according to the lunar phase revealed that high GSI occurred around the last quarter moon for S. argenteus and the new moon for S. spinus . In the ovaries, oocytes developed synchronously, and postovulatory follicles, an indicator of spawning, were observed after the respective moon phase, suggesting that these species are restricted lunar-synchronized spawners. Comparisons of the reproductive activity of the two rabbitfishes in the Chuuk lagoon with that in Okinawa waters revealed that there is a geographic difference in the reproductive activity between habitats. However, the lunar phase for exertion of synchronous gonadal maturation and spawning is common in both regions.     

Induced spat production from Ostrea chilensis Philippi 1845 in mid-winter

Oysters transferred from south to north-central Chile were induced to mature and spawn outside their natural breeding season. The larvae were set on shell particles and whole shell as cultch, and early growth data were obtained. Hatchery production of this species in winter months may help the development of commercial oyster production in southern Chile which is currently limited by summer spatfall.     

Outdoor mass microalgae production in Bahia Kino, Sonora, NW Mexico

The diatom Chaetoceros muelleri was grown in outdoor mass cultures under the winter, spring and summer conditions of Bahia Kino, Sonora, NW Mexico. The solar irradiance in winter was close to 60% of that available in spring and summer, but the cell concentrations and the harvestable biomass were one order of magnitude higher in spring and summer than in winter. There was no difference between the biomass harvested after 2 and 3 days in winter and summer, whereas in spring it was higher after 3 days. The protein content was significantly lower in winter, and carbohydrates and lipids were higher in winter and spring. The number of cells and the amount of harvestable biomass of outdoor cultures of C. muelleri depend on the temperature prevailing in each season, which causes significant differences in growth rates and in biochemical composition.     

Effects of thyroid hormone on gonadotropin-induced steroid production in medaka,Oryzias latipes,ovarian follicles

Blood and ovarian samples were collected at intervals of 4h prior to spawning time from medaka (Oryzias latipes) that were maturationally synchronized with artificial photoperiod (14h light: 10h dark). Plasma estradiol-17β (E₂) levels increased rapidly from 16h before spawning and peaked at 8h before spawning. Follicle-enclosed oocytes (ovarian follicles) at different stages of development were isolated from the ovaries and used to study the in vitro effects of thyroid hormone (triiodothyronine; T₃) on pregnant mare serum gonadotropin (GTH)-induced E₂ production. GTH at a concentration of 100 IU/ml stimulated E₂ production by ovarian follicles collected between 32 and 16h before spawning. At 32h before spawning, T₃ (5 ng/ml) administered along with GTH (100 IU/ml) resulted in a 3.5 fold increase in E₂ production, compared with GTH administered alone. These results suggest that T₃ can act on ovarian follicles directly to modulate GTH-stimulated E₂ production in the medaka.     

The effect of multiple laparotomies,biopsies and feeding on the oocytes of Rana catesbeiana

The ovaries of adult female bullfrogs with immature (stages I to III) and mature (stages IV and V) oocytes were not affected by repeated removal of ovarian samples over a period of 25 days. The surgical procedure proved to be an effective way to ascertain and follow ovarian development.     

半滑舌鳎卵巢发育的组织学和形态数量特征研究

采用组织学方法系统研究了人工养殖条件下半滑舌鳎亲鱼卵巢的组织发育周年变化特征.结果表明,卵母细胞发育可分为6个时相,卵巢发育分为6期.卵巢不同发育时期都由不同类型的卵母细胞组成,半滑舌鳎为非同步分批多次产卵类型.周年发育过程中,6月龄前的鱼卵巢发育处于第Ⅰ期;9～12月龄卵巢可发育至第Ⅱ期;12月龄半滑舌鳎性腺可发育达到Ⅲ期,并一直保持至24月龄.3龄雌鱼达到性成熟,卵巢可发育至第Ⅳ期;随着水温和光周期的调控,卵巢发育进入成熟期(Ⅴ期),发生水合现象是卵母细胞成熟并准备排卵的信号;产卵结束后卵巢退化至第Ⅵ期,排出的卵母细胞退化吸收,以Ⅲ期卵巢越冬后,卵巢退化至Ⅱ期并持续至下一个繁殖周期.人工养殖条件下,卵巢内存在卵母细胞闭锁现象.性腺周年发育过程中,性腺指数(GSI)在性腺达到成熟期时达到峰值,产卵结束后性腺快速退化,GSI值各月份差异显著(P<0.05),亲鱼性腺重量在卵巢发育成熟过程中一直处于生长状态.亲鱼肝脏指数(HSI)在产卵前7～8月份(性腺达到成熟期前30 d左右)达到最大,表明7～8月份是性腺进行卵子发育、卵黄能量储备的重要时期,亲鱼在产卵前通过积极摄食储备体内能量,肝脏在卵母细胞卵黄积累方面具有重要的生理作用.肥满度(CF)值在繁殖盛期10～11月份达到最大,表现出与GSI类似的变化趋势.     

The Effects of Season and Site of Catch on Morphometric Characteristics,Mineral Content,and Fatty Acids of Sardines (Sardina pilchardus) Caught on the Algerian Coast

The variation of morphometrics, mineral content, and fatty acid composition of sardines was determined in relation to season and site of catch in the Mediterranean Sea. Sardines were caught in two regions of the Algerian coast: Mostaganem and Béni-Saf. In both sites, the contents of phosphorus (223 and 211 mg 100 g^?1) and sodium (95 and 10 mg 100 g^?1) were higher in June than in February. Total lipid content was related to the season, being low in winter (2.9%) and high in summer (11.3%). The fatty acid composition shows a high content of polyunsaturated fatty acids (PUFA) dominated by n-3 fatty acids eicosapentaenoic acid (EPA C20:5 n-3; 10%) and docosahexaenoic acid (DHA C22:6n-3; 25%). However, the content of n-6 fatty acids was relatively low both in winter (3.4%) and summer (4.7%). The saturated fatty acid (SFA) content was appreciable in sardines, which range from 34% to 37% according to season. This is in agreement with the literature related to the Mediterranean sardine.     

Serotonin induces ovarian maturation in giant freshwater prawn broodstock, Macrobrachium rosenbergii de Man

This study investigated the effects of serotonin (5-hydroxytryptamine or 5HT) on ovarian development in Macrobrachium rosenbergii de Man. Adult female prawns at the ovarian stage I (spent) were injected with 5HT at 1, 5, 10, 20 and 50 μg g^− 1 body weight (BW) intramuscularly on days 0, 5 and 10, and sacrificed on day 15. The doses as related to the effect could be categorized into three levels: low (1 and 5 μg g^− 1 BW of 5HT), medium (10 and 20 μg g^− 1 BW of 5HT) and high (50 μg g^− 1 BW of 5HT). The low-dose, especially at 1 μg g^− 1 BW, caused prawns to exhibit a significant increase in ovarian index (ovarian weight/body weight × 100) (5.79 ± 0.09%) as compared to the control (1.49%). The ovaries of most of these prawns could develop to stage IV (mature) and contained synchronously mature oocytes while most of the control ovaries remained at stage I and II (proliferative), and contained only oogonia to previtellogenic (Oc1, Oc2) and early vitellogenic oocytes (Oc3). The medium- and high-dose treated prawns exhibited ovaries that could reach stages III and IV and contained various types of oocytes of different maturity. Pretreatment with 5HT receptor antagonist, cyproheptadine (CYP), at 10 μg g^− 1 BW before 5HT injection significantly suppressed the effect of 5HT. Intramuscular injection of the 5HT-primed thoracic ganglion culture medium into CYP-pretreated prawns resulted in the increase of ovarian index about 5–6 times more than in the control, and in the groups injected with 5HT-primed media from muscle strip, eyestalk and brain. The ovaries of most prawn could develop up to stage IV and contained synchronously developed vitellogenic (Oc4) and mature oocytes (Oc5). These findings suggest that 5HT indirectly induces ovarian development and oocytes maturation in M. rosenbergii, probably via a putative ovarian stimulating factor released from the thoracic ganglia.