Reproductive cycle of purple clam, Amiantis purpurata (Bivalvia: Veneridae) in northern Patagonia (Argentina)

2005 ◽  
Vol 85 (2) ◽  
pp. 367-373 ◽  
Author(s):  
Enrique M. Morsan ◽  
Marina A. Kroeck
Keyword(s):  
Reproductive Cycle ◽  
Continuous Process ◽  
Early Summer ◽  
Maturation Stage ◽  
Reproductive Pattern ◽  
Oocyte Diameter ◽  
Histological Techniques ◽  
Northern Patagonia ◽  
History Of ◽  
Quantitative Indicators

The reproductive cycle of the purple clam (Amiantis purpurata) northern Patagonian population was studied throughout a 19-month period (September 1993–March 1995) using standard histological techniques and quantitative indicators (oocyte diameter distributions, oocytes per ocular field and relative oocyte area). In this species gametogenesis is a continuous process involving a complete gonadal restitution after the end of the reproductive season (no resting period). The proliferation phase occurs during the coldest half of the year (April to September) and maturation takes place during spring (September to December). Several partial emissions of gametes, with subsequent restitution of the gametogenic series, occur during the summer months. During the total maturation stage, oocytes never filled the whole alveolar area: maximum per cent of alveolar sections occupied by oocytes (46%) was observed in late spring–early summer. Implications of the reproductive pattern in the context of palaeogeographic history of northern Patagonia, and the isolation of this population are discussed.

scholarly journals Seasonal Variability of SST Fronts in the Inner Sea of Chiloé and Its Adjacent Coastal Ocean, Northern Patagonia

2021 ◽  
Vol 13 (2) ◽  
pp. 181
Author(s):  
Gonzalo S. Saldías ◽  
Wilber Hernández ◽  
Carlos Lara ◽  
Richard Muñoz ◽  
Cristian Rojas ◽  
...  
Keyword(s):  
Coastal Upwelling ◽  
Environmental Variability ◽  
Function Analysis ◽  
Coastal Ocean ◽  
Dominant Mode ◽  
Early Summer ◽  
High Biological Activity ◽  
Northern Patagonia ◽  
Sst Gradient ◽  
Sst Fronts

Surface oceanic fronts are regions characterized by high biological activity. Here, Sea Surface Temperature (SST) fronts are analyzed for the period 2003–2019 using the Multi-scale Ultra-high Resolution (MUR) SST product in northern Patagonia, a coastal region with high environmental variability through river discharges and coastal upwelling events. SST gradient magnitudes were maximum off Chiloé Island in summer and fall, coherent with the highest frontal probability in the coastal oceanic area, which would correspond to the formation of a coastal upwelling front in the meridional direction. Increased gradient magnitudes in the Inner Sea of Chiloé (ISC) were found primarily in spring and summer. The frontal probability analysis revealed the highest occurrences were confined to the northern area (north of Desertores Islands) and around the southern border of Boca del Guafo. An Empirical Orthogonal Function analysis was performed to clarify the dominant modes of variability in SST gradient magnitudes. The meridional coastal fronts explained the dominant mode (78% of the variance) off Chiloé Island, which dominates in summer, whereas the SST fronts inside the ISC (second mode; 15.8%) were found to dominate in spring and early summer (October–January). Future efforts are suggested focusing on high frontal probability areas to study the vertical structure and variability of the coastal fronts in the ISC and its adjacent coastal ocean.

The Gastropod Genus Bembicium Philippi

1958 ◽  
Vol 9 (4) ◽  
pp. 546 ◽  
Author(s):  
H Anderson
Keyword(s):  
Early Summer ◽  
Egg Masses ◽  
Estuarine Species ◽  
History Of ◽  
Living Species ◽  
The Times

A history of the nomenclature of the littorinid genus, Bembicium Phllippi, 1846, and its characters are given, and the anatomy of species of the genus is discussed. Three species are recognized and redescribed: a reef-living species, B. nanum (Lamarck); an estuarine species, B. auratum (Quoy & Gaimard); and the species B. melanostoma (Gmelin) which normally inhabits sheltered bays and inlets. Although all are intertidal animals, and show some measure of adaptability, each appears to be best suited to a particular habitat. B. melanostoma and B. nanum are usually found where the chlorinity of the water is close to that of the sea. B. auratum can withstand considerable variation in the chlorinity of its environment for periods of time which are not likely to be exceeded in its normal habitat. B. melanostoma mostly lives at higher tidal levels than B. nanum. In the aquarium B. nanum proved the most susceptible to desiccation. The egg masses of B. melanostoma contain fewer and larger eggs than those of B. auratum. In the laboratory spawning of B. auratum occurred during the spring and early summer. Under the same conditions specimens of B. melanostoma deposited eggs in October. The differences between the eggs and their development, and between the times of spawning of the two species collected from different littoral regions are also discussed.

Reproductive cycle of the Manila clam (Ruditapes philippinarum): an intensively harvested invasive species in the Tagus Estuary (Portugal)

2017 ◽  
Vol 98 (7) ◽  
pp. 1645-1657 ◽  
Author(s):  
Paula Moura ◽  
Paulo Vasconcelos ◽  
Fábio Pereira ◽  
Paula Chainho ◽  
José Lino Costa ◽  
...  
Keyword(s):  
Invasive Species ◽  
Reproductive Cycle ◽  
Sexual Maturity ◽  
Ruditapes Philippinarum ◽  
Manila Clam ◽  
Tagus Estuary ◽  
Gonad Maturation ◽  
Oocyte Diameter ◽  
Ruditapes Decussatus ◽  
Spawning Period

The present study aimed to describe the reproductive cycle and estimate the size at sexual maturity of the Manila clam (Ruditapes philippinarum) in the Tagus Estuary (Portugal). Specimens were collected monthly from September 2013 to December 2015 during fishing surveys using bivalve dredges. The gametogenic cycle was described in detail using gonad histology and monitored throughout the study period by the monthly variation in the frequency of gonad maturation stages, mean gonadal index and mean oocyte diameter. This invasive population of R. philippinarum displayed synchronous gonadal development between sexes, with ripening occurring mainly in April and May followed by an extensive spawning period until November–December. Individuals reached the size at first sexual maturity at 29.4 mm in shell length (i.e. before 1 year old). Furthermore, the reproductive strategy, dynamics and potential were compared between the invasive R. philippinarum and the native congeneric carpet shell clam (Ruditapes decussatus). Overall, the data gathered in this study constitutes valuable baseline information to propose conservation strategies and implement management measures to minimize the harmful impacts caused by this invasive species on local ecosystems and native biodiversity, particularly over populations of autochthonous bivalves.

scholarly journals Distribution and reproductive biology of the Electric ray Discopyge tschudii Heckel, 1846 in San Matías Gulf, Northern Patagonia, Argentina

2011 ◽  
Vol 9 (4) ◽  
pp. 831-838 ◽  
Author(s):  
Marilú Estalles ◽  
Nidia Marina Coller ◽  
Edgardo Ernesto Di Giácomo ◽  
María Raquel Perier
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Biology ◽  
Reproductive Cycle ◽  
Southern Chile ◽  
Southern Brazil ◽  
Southwest Atlantic ◽  
Aggregate Distribution ◽  
Northern Patagonia ◽  
Southeast Pacific ◽  
Discopyge Tschudii

The Electric ray Discopyge tschudii is distributed in the Southwest Atlantic from southern Brazil to southern Argentina and in the Southeast Pacific from Peru to southern Chile. The main threat to this species is fishing. Discopyge tschudii is noncommercial and individuals caught are discarded on board. The present study analyzes the distribution and the morphological and reproductive characteristics of this ray in San Matías Gulf (SMG), Argentina. A total of 1087 individuals were analyzed. The species presented an aggregate distribution, with the main concentrations in the northern and eastern areas of SMG, at depths below 100 m. Males ranged from 9 to 43 cm and females from 11 to 38 cm. The species presented sexual dimorphism. Males were larger and heavier than females and also matured at larger sizes. Size at 50% of maturity was estimated at 30 cm for males and 21 cm for females. A total of 199 embryos were sampled and the proportion of sexes showed no significant differences from the expected 1:1. The number of embryos per female varied from 1 to 12. The most frequent values were 2 and 5. Length at birth was estimated at 82.17 ± 3.87 mm. Based on our findings, we hypothesize that the electric ray D. tschudii completes its reproductive cycle in SMG.

scholarly journals Reproductive biology of Sympterygia bonapartii (Chondrichthyes: Rajiformes: Arhynchobatidae) in San Matías Gulf, Patagonia, Argentina

2017 ◽  
Vol 15 (1) ◽  
Author(s):  
María L. Estalles ◽  
María R. Perier ◽  
Edgardo E. Di Giácomo
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Biology ◽  
Early Spring ◽  
Egg Laying ◽  
Reproductive Pattern ◽  
Reproductive Parameters ◽  
Egg Capsules ◽  
Northern Patagonia ◽  
Total Length

ABSTRACT This study estimates and analyses the reproductive parameters and cycle of Sympterygia bonapartii in San Matías Gulf, northern Patagonia, Argentina. A total of 827 males and 1,299 females were analysed. Males ranged from 185 to 687 mm of total length (TL) and females from 180 to 742 mm TL. Sexual dimorphism was detected; females were larger, heavier, exhibited heavier livers, wider discs and matured at lager sizes than males. Immature females ranged from 180 to 625 mm TL, maturing females from 408 to 720 mm TL, mature ones from 514 to 742 mm TL and females with egg capsules from 580 to 730 mm TL. Immature males ranged from 185 to 545 mm TL, maturing ones from 410 to 620 mm TL and mature males from 505 to 687 mm TL. Size at which 50% of the skates reached maturity was estimated to be 545 mm TL for males and 594 mm TL for females. According to the reproductive indexes analysed, S. bonapartii exhibited a seasonal reproductive pattern. Mating may occur during winter-early spring and the egg-laying season, during spring and summer.

scholarly journals Reproductive cycle of male wall lizard, Podarcis vaucheri (Reptilia: Sauria: Lacertidae), in Djurdjura, Northern Algeria

2017 ◽  
Author(s):  
Rabah Mamou ◽  
Elara Moudilou ◽  
Jean-Marie Exbrayat ◽  
Mansour Amroun
Keyword(s):  
Sexual Activity ◽  
Reproductive Cycle ◽  
Mixed Type ◽  
Progressive Increase ◽  
Early Summer ◽  
Seminiferous Tubules ◽  
Testis Weight ◽  
Field Observations ◽  
Testicular Weight ◽  
Resting Period

The reproductive cycle of male wall lizard Podarcis vaucheri (Boulenger, 1905) living in Djurdjura mountain, was analyzed from April till October 2014. Its seasonal mixed-type cycle was characterized by three phases: sexual activity, quiescence and recrudescence. After the emergence of lizard from hibernation an intense sexual activity was observed in spring (April, May, and June) at which the testicular weight and seminiferous tubules diameter reached their maximal values. At this period, spermiogenesis was also maximal and the spermiation allowed the release of a large quantity of spermatozoa in both the seminiferous tubules and epididymis lumen. In July, a short sexual resting period followed, during which the testes mass and seminiferous tubules diameter decreased. Spermatogonia and some primary spermatocytes were observed against the wall of seminiferous tubules. The recrudescence period (August, September and October) was characterized by a progressive increase of the testis weight and seminiferous tubules diameter. Spermatocytogenesis began in August, and spermiogenesis occurred in September and October, before the diapause period. But the presence of spermatozoids was not signaled in the epididymis lumen. Field observations and microscopic evidence of testis showed that both sexes reproduced synchronously during spring and early summer.

When did We Start to Change Things?

2009 ◽  
Author(s):  
Thomas N. Sherratt ◽  
David M. Wilkinson
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Science Fiction ◽  
Early Summer ◽  
Current Evidence ◽  
Future Climate Change ◽  
Worst Case ◽  
History Of ◽  
The Subject ◽  
James Lovelock

As we wrote the first draft of this chapter (during early summer 2007), the potential dangers of ‘global warming’ had moved up the news agenda to a point where most major politicians were starting to take the problem seriously. Our opening quotation comes from a book published in early 2006, which seemed to coincide with the growth of this wider concern with global warming. Lovelock was not alone in trying to raise awareness of the problem; around the same time another book on climate change by the zoologist and palaeontologist Tim Flannery also attracted global attention to this issue, as did the lecture tours (and Oscar-winning film) of Al Gore—the former US presidential candidate and campaigner on the dangers of climate change. Indeed, in his role as a climate campaigner Gore won a share in the 2007 Nobel Peace Prize. It is possible that future historians will see the period 2005–2007 as the start of a crucial wider engagement with these problems. Things may not be as bad as James Lovelock suggests—in his book he deliberately emphasized the most worrying scenarios coming from computer models, and other evidence, in an attempt to draw attention to the critical nature of the problem. However, all these worst case scenarios were drawn from within the range of results that most climate scientists believed could plausibly happen—not extreme cases with little current evidence to support them. That one of the major environmental scientists of the second half of the twentieth century could write such prose as science—rather than science fiction—is clearly a case for concern about future climate change. It also raises another important question, relating to the history of human influence on our planet: when in our history did we start to have major environmental impacts on Earth as a whole? This is clearly an important issue from a historical perspective, but the answers may also have implications for some of our attempts to rectify the damage. Our discussion of this question comes with various caveats. Many of the arguments we consider in this chapter are still the subject of academic disagreement.

scholarly journals Goodby Columbus and all that: history and textual criticism

1993 ◽  
Vol 67 (3-4) ◽  
pp. 281-284
Author(s):  
Teofilo F. Ruiz
Keyword(s):  
Textual Criticism ◽  
Continuous Process ◽  
Historical Context ◽  
Recovered Memories ◽  
Christopher Columbus ◽  
Cambridge University ◽  
Oxford University ◽  
University Of Arizona ◽  
History Of ◽  
First Americans

[First paragraph]Columbus. FELIPE FERNANDEZ-ARMESTO. Oxford: Oxford University Press, 1991. xxvii + 218 pp. (Cloth US$ 16.95, Paper US$ 6.99)The Worlds of Christopher Columbus. WILLIAM D. PHILLIPS, JR. & CARLA RAHN PHILLIPS. Cambridge: Cambridge University Press, 1992. xii + 322 pp. (Cloth US$ 27.95)In Search of Columbus: The Sources for the First Voyage. DAVID HENIGE. Tucson: University of Arizona Press, 1991. xiii + 359 pp. (Cloth US$ 29.95)Columbus and the Golden World of the Island Arawaks: The Story of the First Americans and Their Caribbean Environment. D.J.R. WALKER. Kingston, Jamaica: Ian Randle, 1992. 320 pp. (Cloth US$ 12.95)By the time this review appears in print, the Quincentenary celebrations and/or deprecations of the event will be slowly fading into most welcomed oblivion. There will be, of course, the unavoidable local commemorations of specific events: the discovery of such and such island, the anniversary of some European misdeed, the struggle for the valley of Mexico; but the collective remembrance of the Encounter/Discovery will have been allowed to run its course. In truth, after a veritable flood of publications, seminars, operas, protests, and ghastly movies, one is not too sorry to see the whole affair put safely away for another century. If there is any consolation to this continuous process of recovered memories and history, it is that a good number of sensible and scholarly works have been published - including some of those reviewed here - which demolish the idealization and glorification of the Atlantic enterprise and set the history of the Encounter/Discovery within a proper historical context.

BIOLOGY AND BEHAVIOR OF ZIMMERMAN PINE MOTH, DIORYCTRIA ZIMMERMANI, IN MICHIGAN

1967 ◽  
Vol 99 (5) ◽  
pp. 529-536 ◽  
Author(s):  
R. B. Carlson ◽  
J. W. Butcher
Keyword(s):  
Life History ◽  
Vertical Distribution ◽  
Uniform Distribution ◽  
Late Summer ◽  
Head Capsule ◽  
Early Summer ◽  
Main Stem ◽  
History Of ◽  
And Behavior ◽  
The Vertical Distribution

AbstractThis paper reports on studies of biology and life history of the Zimmerman pine moth, Dioryctria zimmermani (Grote), in southern Michigan.Adults emerged during the last 3 weeks of August and eggs hatched through mid-September. Eggs were laid almost entirely on the main stem and, upon hatching, the larvae entered recesses in the bark and spun hibernacula, ostensibly without feeding.Studies on the vertical distribution of larvae and pupae showed a fairly uniform distribution over the main stem in spring and early summer. In late summer, a larger percentage was found in middle whorls.Based on head capsule measurements, it is tentatively proposed that there are six larval stadia. Occurrence of parasitism in the last larval stadia is discussed, and a new egg parasite is reported.The presence of D. abietivorella Grote in the study areas is noted, and discussed briefly.

Determination of Sexual Maturation Stages of Atlantic Salmon (Salmo salar) Captured at Sea

1981 ◽  
Vol 38 (4) ◽  
pp. 405-413 ◽  
Author(s):  
D. R. Idler ◽  
S. J. Hwang ◽  
L. W. Crim ◽  
D. Reddin
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Gonadosomatic Index ◽  
Gonadal Development ◽  
Maturation Stage ◽  
Female Fish ◽  
Histological Techniques ◽  
Atlantic Salmon Salmo Salar ◽  
Placentia Bay

Radioimmunoassay (RIA) of plasma vitellogenin (Vg), estradiol (E2), 11-ketotestosterone (11-keto), and gonadotropin (GtH), together with histological techniques were evaluated for determination of the maturation stage of Atlantic salmon (Salmo salar) at sea.Male salmon had lower plasma Vg, E2, and higher 11-keto levels and could be distinguished from females several months in advance of spawning. Six female salmon were tagged at sea in 1975 in Placentia Bay and samples of blood taken. When the fish were recovered in rivers the lowest plasma Vg value was 396 μg/mL. This formed the basis of a working hypothesis, that fish with Vg values in excess of 396 μg/mL (~5–6 mo before spawning) will spawn in the year of capture. This hypothesis was supported by the Vg values of an additional 19 tagged females recaptured in Newfoundland and mainland rivers and brackish water off mainland rivers in 1976.Significant correlations between stage of gonadal development and plasma Vg, stage of gonadal development and gonadosomatic index (GSI), stage of gonadal development and plasma E2, plasma Vg and plasma E2, GSI and plasma E2, and between plasma Vg and 11-keto values were found for the female fish. The gonadal development of female fish from Bonavista Bay ranged between oil globule stage and secondary yolk stage. All those females which had reached the primary yolk stage would almost certainly mature and may be considered spawners of the year; on this basis 91% of the females were spawners of the year. Based on the minimum plasma Vg values, at sea, for fish which subsequently returned to the rivers, there were 86% spawners of the year among female salmon taken in Bonavista Bay. Based on plasma Vg levels, spawners of the year ranged from essentially zero in Greenland (fish captured in Greenland during August–November are not spawners of the year, except for the very few that spawn in one Greenland river) to 100% for fish caught in several other fisheries.11-Ketotestosterone was higher in the male fish than in the female fish and there was a correlation between GSI and 11-keto for male fish.The plasma GtH content of fish taken in the sea was extremely low as measured by RIA.Key words: salmon, maturation, migration, radioimmunoassay, vitellogenin, estradiol, gonadotropin, 11-ketotestosterone, histology, gonadosomatic index

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