scholarly journals Asynchronous reproduction and multi-spawning in the coral-excavating sponge Cliona delitrix

2015 ◽  
Vol 96 (2) ◽  
pp. 515-528 ◽  
Author(s):  
Andia Chaves-Fonnegra ◽  
Manuel Maldonado ◽  
Patricia Blackwelder ◽  
Jose V. Lopez
Keyword(s):  
Reproductive Cycle ◽  
Full Moon ◽  
Seawater Temperature ◽  
Coral Mortality ◽  
Multiple Spawning ◽  
Excavating Sponges ◽  
Male Gametes ◽  
Transmission Electron ◽  
Reef Health ◽  
Granulose Cells

Cliona delitrix is one of the most abundant and destructive coral-excavating sponges on Caribbean reefs. However, basic aspects of its reproductive biology, which largely determine the species propagation potential, remain unknown. A 2-year study (October 2009 to September 2011) was conducted to determine the reproductive cycle and gametogenesis of a C. delitrix population located in a shallow reef in Florida, USA. Mesohyl tissue collected from randomly chosen and tagged sponge individuals was sampled one to several times a month, and analysed by light and transmission electron microscopy (TEM). Cliona delitrix is oviparous and gonochoric, except for a few simultaneous hermaphroditic individuals. The C. delitrix reproductive cycle in Florida is from April to December, and is triggered by an increase in seawater temperature to 25°C. Oogenesis and spermatogenesis were asynchronous among individuals; with different cohorts of oocytes co-occurring in females, and spermatic cysts in males. Granulose cells acted as nurse cells, contributing to the growth and maturation of both female and male gametes. Spawning of gametes was not always synchronized with full moon phase. Unlike most other oviparous sponges, the reproductive cycle of C. delitrix is versatile and includes multiple spawning events during the summer of each year. This characteristic maximizes sponge propagation on coral reefs during the warmer months of the year, particularly when thermal stress induces coral mortality. This aspect, combined with its success on polluted areas, make C. delitrix a suitable bioindicator of coral reef health.

Bioeroding sponge assemblages: the importance of substrate availability and sediment

2018 ◽  
Vol 99 (2) ◽  
pp. 343-358 ◽  
Author(s):  
Joseph Marlow ◽  
Christine H.L. Schönberg ◽  
Simon K. Davy ◽  
Abdul Haris ◽  
Jamaluddin Jompa ◽  
...  
Keyword(s):  
Coral Reef ◽  
Environmental Factors ◽  
Spatial Variation ◽  
Environmental Conditions ◽  
Sponge Species ◽  
Coral Mortality ◽  
Substrate Availability ◽  
Abiotic Conditions ◽  
Assemblage Composition ◽  
Reef Health

Despite global deterioration of coral reef health, not all reef-associated organisms are in decline. Bioeroding sponges are thought to be largely resistant to the factors that stress and kill corals, and are increasing in abundance on many reefs. However, there is a paucity of information on how environmental factors influence spatial variation in the distribution of these sponges, and how they might be affected by different stressors. We aimed to identify the factors that explained differences in bioeroding sponge abundance and assemblage composition, and to determine whether bioeroding sponges benefit from the same environmental conditions that can contribute towards coral mortality. Abundance surveys were conducted in the Wakatobi region of Indonesia on reefs characterized by different biotic and abiotic conditions. Bioeroding sponges occupied an average of 8.9% of available dead substrate and variation in abundance and assemblage composition was primarily attributed to differences in the availability of dead substrate. Our results imply that if dead substrate availability increases as a consequence of coral mortality, bioeroding sponge abundance is also likely to increase. However, bioeroding sponge abundance was lowest on a sedimented reef, despite abundant dead substrate. This suggests that not all forms of coral mortality will benefit all bioeroding sponge species, and sediment-degraded reefs are likely to be dominated by a few resilient bioeroding sponge species. Overall, we demonstrate the importance of understanding the drivers of bioeroding sponge abundance and assemblage composition in order to predict possible impacts of different stressors on reefs communities.

scholarly journals Dynamics of ovarian maturation during the reproductive cycle of Metynnis maculatus, a reservoir invasive fish species (Teleostei: Characiformes)

2013 ◽  
Vol 11 (4) ◽  
pp. 821-830 ◽  
Author(s):  
Thiago Scremin Boscolo Pereira ◽  
Renata Guimarães Moreira ◽  
Sergio Ricardo Batlouni
Keyword(s):  
Reproductive Cycle ◽  
Ovarian Development ◽  
Gonadosomatic Index ◽  
Ovarian Maturation ◽  
Invasive Fish ◽  
Multiple Spawning ◽  
Adult Females ◽  
The Mean ◽  
Ovulatory Follicles ◽  
Morphometric Evaluation

In this study, we evaluated the dynamics of ovarian maturation and the spawning processes during the reproductive cycle of Metynnis maculatus. Adult females (n = 36) were collected bimonthly between April 2010 and March 2011. The mean gonadosomatic index (GSI) was determined, ovarian and blood samples were submitted for morphometric evaluation and the steroid plasma concentration was determined by ELISA. This species demonstrated asynchronous ovarian development with multiple spawns. This study revealed that, although defined as a multiple spawning species, the ovaries of M. maculatus have a pattern of development with a predominance of vitellogenesis between April and August and have an intensification in spawning in September; in October, a drop in the mean GSI values occurred, and the highest frequencies of post-ovulatory follicles (POFs) were observed. We observed a positive correlation between the POF and the levels of 17α-hydroxyprogesterone. Metynnis maculatus has the potential to be used as a source of pituitary tissue for the preparation of crude extracts for hormonal induction; the theoretical period for use is from September to December, but specific studies to determine the feasibility of this approach must be conducted.

Changes in the expression of pituitary gonadotropin subunits during reproductive cycle of multiple spawning female chub mackerel Scomber japonicus

2011 ◽  
Vol 38 (3) ◽  
pp. 883-897 ◽  
Author(s):  
Mitsuo Nyuji ◽  
Sethu Selvaraj ◽  
Hajime Kitano ◽  
Hirofumi Ohga ◽  
Michio Yoneda ◽  
...  
Keyword(s):  
Reproductive Cycle ◽  
Scomber Japonicus ◽  
Chub Mackerel ◽  
Multiple Spawning ◽  
Pituitary Gonadotropin

scholarly journals Loss of symbiont infectivity following thermal stress can be a factor limiting recovery from bleaching in cnidarians

2020 ◽  
Vol 14 (12) ◽  
pp. 3149-3152 ◽  
Author(s):  
Mariko Kishimoto ◽  
Andrew H. Baird ◽  
Shinichiro Maruyama ◽  
Jun Minagawa ◽  
Shunichi Takahashi
Keyword(s):  
Heat Stress ◽  
Seawater Temperature ◽  
External Environment ◽  
Host Cells ◽  
Coral Mortality ◽  
Free Living ◽  
Experimental Conditions ◽  
Symbiotic Algae ◽  
The Family ◽  
In The Wild

Abstract Increases in seawater temperature can cause coral bleaching through loss of symbiotic algae (dinoflagellates of the family Symbiodiniaceae). Corals can recover from bleaching by recruiting algae into host cells from the residual symbiont population or from the external environment. However, the high coral mortality that often follows mass-bleaching events suggests that recovery is often limited in the wild. Here, we examine the effect of pre-exposure to heat stress on the capacity of symbiotic algae to infect cnidarian hosts using the Aiptasia (sea-anemone)-Symbiodiniaceae model system. We found that the symbiont strain Breviolum sp. CS-164 (ITS2 type B1), both free-living and in symbiosis, loses the capacity to infect the host following exposure to heat stress. This loss of infectivity is reversible, however, a longer exposure to heat stress increases the time taken for reversal. Under the same experimental conditions, the loss of infectivity was not observed in another strain Breviolum psygmophilum CCMP2459 (ITS2 type B2). Our results suggest that recovery from bleaching can be limited by the loss of symbiont infectivity following exposure to heat stress.

scholarly journals Ultrastructure of the mature spermatozoon of Eubothrium rugosum (Batsch, 1786) with a re-assessment of the spermatozoon ultrastructure of Eubothrium crassum (Bloch, 1779) (Cestoda: Bothriocephalidea)

2010 ◽  
Vol 47 (4) ◽  
pp. 257-263 ◽  
Author(s):  
M. Bruňanská ◽  
H.-P. Fagerholm ◽  
J. Nebesářová ◽  
B. Kostič
Keyword(s):  
Posterior Extremity ◽  
Posterior Part ◽  
Mature Spermatozoon ◽  
Structural Polymorphism ◽  
Dense Granules ◽  
Male Gametes ◽  
Transmission Electron ◽  
Anterior Ring ◽  
First Time ◽  
Region Ii

AbstractThe ultrastructure of the mature spermatozoon of the bothriocephalidean tapeworm Eubothrium rugosum, a parasite of the burbot, Lota lota (L.), was studied by transmission electron microscopy for the first time. In addition, spermatozoon ultrastructure of Eubothrium crassum has been re-assessed. New is the finding, that the mature spermatozoa of both species of the genus Eubothrium exhibit essentially the same general morphology. They are filiform cells tapering at both extremities, and they possess the two axonemes with 9+“1” pattern of Trepaxonemata, attachment zones, a nucleus, cortical microtubules (CMs), electron-dense granules, and a single crested body. Structural polymorphism of the CBs has been found within the two Eubothrium species for the first time. The anterior ring of electron-dense tubular structures surrounding a single axoneme marks the border between the two defined regions, region I and region II of the spermatozoon. This unique feature has only been observed in the Bothriocephalidea. The anuclear axoneme region II of Eubothrium spermatozoa fluently verges into a nuclear region III. The posterior part of the spermatozoon contains one-axoneme, few CMs and a posterior extremity of the nucleus that subsequently disappears. The posterior extremity of the male gametes of the genus Eubothrium exhibits elements of a disorganized axoneme which characterize also spermatozoa of the family Triaenophoridae. Discussed are interspecific similarities and differences between the spermatozoa of the two Eubothrium species as well as between these and other Eucestoda.

Annual reproductive cycle of the Japanese holothurian Eupentacta chronhjelmi

1994 ◽  
Vol 72 (3) ◽  
pp. 387-396 ◽  
Author(s):  
Maria Antonina B. Catalan ◽  
Masamichi Yamamoto
Keyword(s):  
Reproductive Cycle ◽  
Wall Thickness ◽  
Histological Analysis ◽  
Seawater Temperature ◽  
Annual Reproductive Cycle ◽  
Index Method ◽  
Ambient Seawater ◽  
The Seto Inland Sea ◽  
Gonadal Index ◽  
Inland Sea Of Japan

The reproductive cycle of the small temperate dendrochirote holothurian Eupentacta chronhjelmi was studied in the intertidal zone of Aoshima Island, in the Seto Inland Sea of Japan, from July 1989 to January 1991. Reproductive status was assessed by the gonadal index method and histological analysis of the largest (tertiary) gonadal tubules. The primary and secondary tubules are cryptic and difficult to find, so no reference to the animal's annual cycle in terms of gametogenesis is made. The gonad wall was thickest in September for females and October for males, when the gonadal index was at its peak the rapid final stages of vitellogenesis in females (and completion of spermatogenesis in males) depleted reserves in the gonad wall, producing gametes that were spawned in October to December. When gametes were spawned in December the gonadal index and gonad wall thickness decreased. We suggest that the gonadal index reflects gonadal growth by oocyte production and an increase in gonad wall thickness. In the laboratory, spawning occurred from midnight to 04:00, at ambient seawater temperature (12 °C). Individuals elevated their anterior, oral end, waved their tentacles, and released gametes for about an hour. Based on its large egg size (300 ± 5 μm (mean ± SE) diameter) and low fecundity (1500 ± 10 ripe oocytes per individual), we infer lecithotropic development with an abbreviated larval stage.

scholarly journals The reproductive cycle of the oyster Crassostrea gasar

2014 ◽  
Vol 74 (4) ◽  
pp. 967-976 ◽  
Author(s):  
CHAM Gomes ◽  
FC Silva ◽  
GR Lopes ◽  
CMR Melo
Keyword(s):  
Reproductive Cycle ◽  
Growth Stage ◽  
Seawater Temperature ◽  
Reproductive Development ◽  
Condition Index ◽  
Early Growth ◽  
Mature Stage ◽  
Salinity Regime ◽  
Early Growth Stage ◽  
Late Growth

The purpose of this study was to analyze the reproductive cycle of the oyster Crassostrea gasar (= C. brasiliana) in the field and the laboratory. The reproductive cycle of the animals was evaluated in the field at Sambaqui Beach, Florianópolis, SC (27° 29′18″ S and 48° 32′12″ W) from May 2008 through November 2009. In July, the animals were in the resting stage. The early growth stage began in August and was followed by the late growth stage in October. In November and December, the oysters began to enter the mature stage. Females in spawning condition were predominant during these months. The stages of the reproductive cycle were positively associated with temperature (r=0.77, P<0.01) and negatively associated with salinity (r=−0.56, P=0.042). These findings demonstrated that increased temperature and reduced salinity influence the reproductive development of Crassostrea gasar. The condition index (CI) of the animals was also associated with the seawater temperature. The highest values of the condition index were observed during the months when the temperature of the seawater was gradually increasing. A laboratory experiment was performed to test the effect of salinity on the reproductive cycle of the oysters. The experiment was conducted in standardized tanks. The animals were conditioned using two salinities (24‰ and 34‰). The salinity regime influenced the development of the gonadal tissue of the oysters. A salinity of 24‰ produced greater reproductive development.

scholarly journals Bioerosion: the other ocean acidification problem

2017 ◽  
Vol 74 (4) ◽  
pp. 895-925 ◽  
Author(s):  
Christine H. L. Schönberg ◽  
James K. H. Fang ◽  
Marina Carreiro-Silva ◽  
Aline Tribollet ◽  
Max Wisshak
Keyword(s):  
Ocean Acidification ◽  
Expert Knowledge ◽  
Experimental Studies ◽  
Coral Mortality ◽  
Global Trends ◽  
Case Examples ◽  
Reef Health ◽  
Natural Counterpart ◽  
Meta Analyses ◽  
Near Future

Bioerosion of calcium carbonate is the natural counterpart of biogenic calcification. Both are affected by ocean acidification (OA). We summarize definitions and concepts in bioerosion research and knowledge in the context of OA, providing case examples and meta-analyses. Chemically mediated bioerosion relies on energy demanding, biologically controlled undersaturation or acid regulation and increases with simulated OA, as does passive dissolution. Through substrate weakening both processes can indirectly enhance mechanical bioerosion, which is not directly affected by OA. The low attention and expert knowledge on bioerosion produced some ambiguous views and approaches, and limitations to experimental studies restricted opportunities to generalize. Comparability of various bioerosion and calcification rates remains difficult. Physiological responses of bioeroders or interactions of environmental factors are insufficiently studied. We stress the importance to foster and advance high quality bioerosion research as global trends suggest the following: (i) growing environmental change (eutrophication, coral mortality, OA) is expected to elevate bioerosion in the near future; (ii) changes harmful to calcifiers may not be as severe for bioeroders (e.g. warming); and (iii) factors facilitating bioerosion often reduce calcification rates (e.g. OA). The combined result means that the natural process bioerosion has itself become a “stress factor”&#x94; for reef health and resilience.

Flagellar apparatus of male gametes and other aspects of gamete and zygote ultrastructure in Prasiola and Rosenvingiella (Chlorophyta, Prasiolales) from British Columbia

1989 ◽  
Vol 67 (2) ◽  
pp. 505-514 ◽  
Author(s):  
Charles J. O'Kelly ◽  
David J. Garbary ◽  
Gary L. Floyd
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Rotational Symmetry ◽  
Flagellar Apparatus ◽  
Zygote Formation ◽  
Structural Elements ◽  
Male Gametes ◽  
Transmission Electron ◽  
Close Relatives ◽  
Flagellar Axoneme

We examined gametes, syngamy, and zygote formation in Prasiola meridionalis Setchell & Gardner and Rosenvingiella constricta (S. & G.) Silva with the transmission electron microscope. We compare the structures we observed with those of the Atlantic species P. stipitata Suhr and describe some previously unreported features. The sperm possessed a number of unusual structural elements in the flagellar apparatus and elsewhere, in particular a 9 + 1 microtubule configuration in the flagellar axoneme. The flagellar apparatus exhibited 180° rotational symmetry and counterclockwise absolute orientation of major components. At syngamy, the flagellar apparatus changed little in composition and arrangement, suggesting that it has a minimal, if any, function in syngamy or the planozygote. Karyogamy occurred within a few hours of plasmogamy, after settlement of the planozygote and concurrently with wall formation. The three species, P. meridionalis, P. stipitata, and R. constricta, are very similar in gamete structure, which indicates that the genera Prasiola and Rosenvingiella are close relatives. The flagellar apparatus features provide evidence supporting recognition of the order Prasiolales, which may be assigned to either the class Ulvophyceae or the class Pleurastrophyceae.

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