Recruitment, settlement and ontogeny of the serpulid 'Spirobranchus cariniferus' (Gray, 1843)

<p>Serpulids are a globally represented group of polychaetes and can be found in many habitats from the intertidal fringe to the subtidal environment and even in deep-sea ecosystems. These tube-dwelling worms are often described as pioneer species in new or disturbed habitats. Serpulids secrete a calcareous tube and often occur in aggregations. These patches can range from several centimetres to several metres in diameter and may even form reef systems. Accumulations of tube-dwelling worms provide a new habitat for other species and, therefore, serpulids are considered bioengineers. Serpulid aggregations are known to enhance biodiversity and species abundance and may increase water quality through their filter activity. Despite their ecological importance, their ecology and ontogeny have received little attention. Spirobranchus cariniferus, a New Zealand endemic intertidal serpulid, is a substantial contributor to intertidal ecosystems. For this and other Serpulidae, the link between larval development and larval settlement is missing. However, this connection is essential to understand recruitment and ecology of tube-dwelling worms. Therefore, in this thesis, I describe the ontogeny of S. cariniferus from larval development to recruitment and reproduction. In the first data chapter, I present my findings on the recruitment of S. cariniferus in the field. This serpulid settles aggregatively in the field but not necessarily in response to the presence of adult conspecifics, as has been previously reported. Abiotic factors such as sunlight or wave disturbance have a more substantial effect on recruitment rather than the occurrence of adult individuals of the same or a competing species. Additionally, this chapter provides support for the hypothesis that larvae of S. cariniferus may accumulate near the substrate before settlement. Many sessile marine invertebrate taxa occur in either aggregations or as solitary individuals, with potential benefits and disadvantages associated with each configuration. For S. cariniferus, solitary and aggregative individuals can be found in the same habitat. Therefore, the second data chapter compares growth and mortality for individuals living alone or in aggregation. While solitary and aggregative individuals elongate their tubes at a similar rate, further correlations of body to tube sizes lead to the conclusion that solitary worms focus more of their energy on tube length growth rather than body size increment compared to aggregative conspecifics. Mortality is highly variable but does not differ between both configurations. However, individuals living in a patch have a better ability to recover from damage to their tubes. In the last two decades, the idea that gonochorism is the general reproductive pattern for Serpulidae has been challenged, and instead it has been suggested by some that protandry is the more common trait. Therefore, with my third data chapter, I explore maturation and sex ratio of S. cariniferus and whether it changes for individuals living alone vs. in aggregation or based on size. While maturation depends on size, sex does not, and neither maturation nor sex ratio are dependent on whether individuals live in aggregation or not. Further, the ratio of females to males did not favour either sex consistently. For the first time in this species I found evidence of possible hermaphroditism. Through spawning trials and histological sections, I identified nine individuals which simultaneously contained oocytes and sperm cells. I suggest therefore, that S. cariniferus has alternating sexes rather than protandry as a reproductive strategy. In the fourth and final data chapter, I describe the metamorphosis and settlement behaviour of S. cariniferus larvae. For this serpulid species, settlement and metamorphosis are separate and distinct steps that involve both behavioural and morphological changes to the larvae. Further, this entire process can be quite prolonged (i.e. over several days), and at some points can be reversed. It is therefore very important that observations last longer than 24–48 hours, when studying serpulid settlement. As far as I am aware, this is the first study on a serpulid species to examine aggregative settlement in the field in relation to the presence of adult conspecifics and abiotic factors, and also to explicitly test for consequences of solitary vs. group living on growth and mortality. It is also the first to show evidence of hermaphroditism in this species. I hope my research and this thesis stimulates a more inclusive and holistic investigation of serpulids in the future. Larval development, settlement patterns and ontogeny need to be studied in detail if we want to understand the evolution, ecology, impacts and benefits of these and other sessile marine invertebrates.</p>

Recruitment, settlement and ontogeny of the serpulid 'Spirobranchus cariniferus' (Gray, 1843)

<p>Serpulids are a globally represented group of polychaetes and can be found in many habitats from the intertidal fringe to the subtidal environment and even in deep-sea ecosystems. These tube-dwelling worms are often described as pioneer species in new or disturbed habitats. Serpulids secrete a calcareous tube and often occur in aggregations. These patches can range from several centimetres to several metres in diameter and may even form reef systems. Accumulations of tube-dwelling worms provide a new habitat for other species and, therefore, serpulids are considered bioengineers. Serpulid aggregations are known to enhance biodiversity and species abundance and may increase water quality through their filter activity. Despite their ecological importance, their ecology and ontogeny have received little attention. Spirobranchus cariniferus, a New Zealand endemic intertidal serpulid, is a substantial contributor to intertidal ecosystems. For this and other Serpulidae, the link between larval development and larval settlement is missing. However, this connection is essential to understand recruitment and ecology of tube-dwelling worms. Therefore, in this thesis, I describe the ontogeny of S. cariniferus from larval development to recruitment and reproduction. In the first data chapter, I present my findings on the recruitment of S. cariniferus in the field. This serpulid settles aggregatively in the field but not necessarily in response to the presence of adult conspecifics, as has been previously reported. Abiotic factors such as sunlight or wave disturbance have a more substantial effect on recruitment rather than the occurrence of adult individuals of the same or a competing species. Additionally, this chapter provides support for the hypothesis that larvae of S. cariniferus may accumulate near the substrate before settlement. Many sessile marine invertebrate taxa occur in either aggregations or as solitary individuals, with potential benefits and disadvantages associated with each configuration. For S. cariniferus, solitary and aggregative individuals can be found in the same habitat. Therefore, the second data chapter compares growth and mortality for individuals living alone or in aggregation. While solitary and aggregative individuals elongate their tubes at a similar rate, further correlations of body to tube sizes lead to the conclusion that solitary worms focus more of their energy on tube length growth rather than body size increment compared to aggregative conspecifics. Mortality is highly variable but does not differ between both configurations. However, individuals living in a patch have a better ability to recover from damage to their tubes. In the last two decades, the idea that gonochorism is the general reproductive pattern for Serpulidae has been challenged, and instead it has been suggested by some that protandry is the more common trait. Therefore, with my third data chapter, I explore maturation and sex ratio of S. cariniferus and whether it changes for individuals living alone vs. in aggregation or based on size. While maturation depends on size, sex does not, and neither maturation nor sex ratio are dependent on whether individuals live in aggregation or not. Further, the ratio of females to males did not favour either sex consistently. For the first time in this species I found evidence of possible hermaphroditism. Through spawning trials and histological sections, I identified nine individuals which simultaneously contained oocytes and sperm cells. I suggest therefore, that S. cariniferus has alternating sexes rather than protandry as a reproductive strategy. In the fourth and final data chapter, I describe the metamorphosis and settlement behaviour of S. cariniferus larvae. For this serpulid species, settlement and metamorphosis are separate and distinct steps that involve both behavioural and morphological changes to the larvae. Further, this entire process can be quite prolonged (i.e. over several days), and at some points can be reversed. It is therefore very important that observations last longer than 24–48 hours, when studying serpulid settlement. As far as I am aware, this is the first study on a serpulid species to examine aggregative settlement in the field in relation to the presence of adult conspecifics and abiotic factors, and also to explicitly test for consequences of solitary vs. group living on growth and mortality. It is also the first to show evidence of hermaphroditism in this species. I hope my research and this thesis stimulates a more inclusive and holistic investigation of serpulids in the future. Larval development, settlement patterns and ontogeny need to be studied in detail if we want to understand the evolution, ecology, impacts and benefits of these and other sessile marine invertebrates.</p>

Comparative transcriptomic analysis of gonadal development and renewal in the ovoviviparous black rockfish (Sebastes schlegelii)

Background The black rockfish (Sebastes schlegelii) has an ovoviviparous reproductive pattern and long-term sperm storage, resulting in asynchronous gonadal development between the sexes. However, the comprehensive understanding of gonadal development in black rockfish has not yet been achieved. Here, we studied gonadal development and germ cell renewal using histology and RNA-seq. Results In this study, RNA-seq was performed on testes and ovaries to characterize key pathways and genes that are active during development and gamete maturation in black rockfish. Differentially expressed genes (DEGs) were identified and annotated in 4 comparisons (F_III vs. F_IV, F_IV vs. F_V, M_III vs. M_IV and M_IV vs. M_V). Based on analysis of DEGs enriched in the testis, 11 and 14 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were mapped to the M_III vs. M_IV group and the M_IV vs. M_V group, respectively. DEGs in ovarian development were also classified into 10 groups according to their biological functions. The expression patterns of the selected genes determined by qPCR were significantly correlated with the RNA-Seq results, supporting the reliability and accuracy of the RNA-Seq analysis. E2 levels showed down regulation from previtellogenesis to mature stage in female and T level showed down regulation from spermatogenesis to regressed stage in the male. Conclusions The categories “intercellular interaction and cytoskeleton”, “molecule amplification” and “repair in the cell cycle” were revealed to be crucial in testis development and spermatogenesis, as was the biosynthesis of a series of metabolites. Our results provide comprehensive insight into black rockfish gonadal development and provide a basis for further study of reproductive physiology and molecular biology in ovoviviparity teleosts.

Abundance, Distribution, Morphometric, Feeding Evaluation and the Reproductive Strategies of Gymnarchus niloticus in the Lower River Niger at Agenebode, Edo State Nigeria

The study of the numerous areas of biology of fish produces ample and relevant information that aids scientist to explore, know and maintain the survival, growth, continuity and sustainability of life of various fish species. A total of 94 specimens of Gymnarchus niloticus were collected from River Niger at Agenebode during the sample period that ranged from 14 – 94 cm total length (54.88± 17.92); weighed 424 - 2281g (1569.61 ± 422.85). The length weight relationship (LWR) of G. niloticus in this study showed a negative (b<3) allometric growth pattern. Out of the 94 specimens analysed 54 males and 40 females were examined with a ratio of 1:1.4. Insects and decapods were the major food of the juveniles of Gymnarchus niloticus while the major food of preference of the sub adults and adults were Fish and insects with 27.12%, and 27.97% by FO. Gymnarchus niloticus possesses a single ovary in the female and single testis in the male which is often referred to as unpaired gonad. Fecundity ranged between 620 to 1378 eggs with a mean of 957.69 ± 112.31 eggs in females. The relationship between fecundity (F) and weight (W) and fecundity and standard length (SL) showed that fecundity is more related to weight than length of fish. Log F = 820.66 + 0.11 W and Log F = 151.23 + 5.31 SL. Fecundity had a positive significant correlation (P<0.05) with both somatic weight (r = 0.714) and standard length (r = 0.657) of fish. Ova diameter showed a ranged between 3.5 and 7.9 mm with a mean of 4.72 ± SD1.69 mm and it had significant relationship (P<0.05) with total weight, gonad weight and maturity stage. Gymnarchus niloticus in the Lower River Niger at Agenebode showed that G. niloticus has an unpaired gonad in both sexes, a gonochoristic reproductive pattern. Fecundity is low and the ova are large. They are small brood spawners with asynchronous breeding strategy. The attributes of G. niloticus obtained from this study reveals that the fish species is a good candidate for fish culture.

Kākāpō reproduction: Identification of steroid receptors and oestrogenic activity in native flora

<p>Kākāpō (Strigops habroptilus) are a critically endangered parrot species endemic to New Zealand that exhibit a reproductive strategy linked to “masting” years. Crucial to their survival is increased reproductive success. It has been hypothesised that their pattern of reproduction is synchronised with a steroidal “trigger” present in plants during intensive masting. If this hypothesis is valid, then Kākāpō and other closely related NZ parrots might be receptive to these masting plants in a manner different from that of other avian species. The aims of this study were firstly, to identify whether unique amino acid motifs were present in the ligand binding domains (LBD) for the steroid receptors oestrogen receptor α (ER-α), oestrogen receptor β (ER-β), androgen receptor (AR) and progesterone receptor (PR) for the New Zealand parrots Kākāpō, Kākā, Kākāriki and Kea. These LBD amino acid sequences were compared with those in an Australian parrot, the Cockatiel, as well as in Chicken and Japanese Quail. Moreover, the role of these amino acid changes on the binding of ligands (both the native ligand and other steroidogenic compounds) for ER-α was assessed by in silico modelling by comparing the most favourable binding position of the ligands in the three-dimensional structure of Kākāpō ER-α with that of human ER-α. The second aim was to test extracts of New Zealand native plants known to be a food source for Kākāpō for their seasonal variation in oestrogenic activity and hence possible involvement in the reproductive cycle of Kākāpō. The LBD for ER-β and AR of the parrot species (New Zealand and Australian) displayed 100% identity whilst those for ER-α and PR had variations. When the parrot sequences were compared with those for other avian species and human, there were a number of amino acid differences present, with the greatest disparity present in the LBD of ER-α. From in silico modelling studies, the amino acid substitutions in this receptor were predicted to have an indirect influence on the binding position of both 17β-oestradiol and a number of phytoestrogens through changes in the structure of this region. Consequently, this could have an effect on the binding affinity of certain plant chemicals for ER-α and thus their potency. Plants extracts from the foliage and fruit of native New Zealand species were screened for oestrogenic activity in a yeast bioassay transfected with the human isoform of ER-α. The results from these experiments indicated that all the plants tested (excluding Dacrycarpus dacrydioides) exhibited detectable oestrogenic activity and a number also displayed variable and sometimes seasonal trends in activity. In summary, the results in this study identified ER-α LBD amino acid motifs unique to New Zealand parrots. For the other steroid receptors, the ER-β LBD had a three amino acid combination of M, V and L that was only present in the parrot species whilst both the AR and PR LBD displayed much greater inter-species conservation. These changes, particularly those in the ER-α LBD, may influence the binding of steroidogenic compounds, known to be present in the plants consumed by Kākāpō as demonstrated by in silico modelling. Thus, this research provides evidence that the diet of Kākāpō may influence their reproductive pattern. However, it remains to be determined whether the steroidogenic potency of these plant extracts is modified when interacting with the unique LBD of native NZ parrots.</p>

Kākāpō reproduction: Identification of steroid receptors and oestrogenic activity in native flora

<p>Kākāpō (Strigops habroptilus) are a critically endangered parrot species endemic to New Zealand that exhibit a reproductive strategy linked to “masting” years. Crucial to their survival is increased reproductive success. It has been hypothesised that their pattern of reproduction is synchronised with a steroidal “trigger” present in plants during intensive masting. If this hypothesis is valid, then Kākāpō and other closely related NZ parrots might be receptive to these masting plants in a manner different from that of other avian species. The aims of this study were firstly, to identify whether unique amino acid motifs were present in the ligand binding domains (LBD) for the steroid receptors oestrogen receptor α (ER-α), oestrogen receptor β (ER-β), androgen receptor (AR) and progesterone receptor (PR) for the New Zealand parrots Kākāpō, Kākā, Kākāriki and Kea. These LBD amino acid sequences were compared with those in an Australian parrot, the Cockatiel, as well as in Chicken and Japanese Quail. Moreover, the role of these amino acid changes on the binding of ligands (both the native ligand and other steroidogenic compounds) for ER-α was assessed by in silico modelling by comparing the most favourable binding position of the ligands in the three-dimensional structure of Kākāpō ER-α with that of human ER-α. The second aim was to test extracts of New Zealand native plants known to be a food source for Kākāpō for their seasonal variation in oestrogenic activity and hence possible involvement in the reproductive cycle of Kākāpō. The LBD for ER-β and AR of the parrot species (New Zealand and Australian) displayed 100% identity whilst those for ER-α and PR had variations. When the parrot sequences were compared with those for other avian species and human, there were a number of amino acid differences present, with the greatest disparity present in the LBD of ER-α. From in silico modelling studies, the amino acid substitutions in this receptor were predicted to have an indirect influence on the binding position of both 17β-oestradiol and a number of phytoestrogens through changes in the structure of this region. Consequently, this could have an effect on the binding affinity of certain plant chemicals for ER-α and thus their potency. Plants extracts from the foliage and fruit of native New Zealand species were screened for oestrogenic activity in a yeast bioassay transfected with the human isoform of ER-α. The results from these experiments indicated that all the plants tested (excluding Dacrycarpus dacrydioides) exhibited detectable oestrogenic activity and a number also displayed variable and sometimes seasonal trends in activity. In summary, the results in this study identified ER-α LBD amino acid motifs unique to New Zealand parrots. For the other steroid receptors, the ER-β LBD had a three amino acid combination of M, V and L that was only present in the parrot species whilst both the AR and PR LBD displayed much greater inter-species conservation. These changes, particularly those in the ER-α LBD, may influence the binding of steroidogenic compounds, known to be present in the plants consumed by Kākāpō as demonstrated by in silico modelling. Thus, this research provides evidence that the diet of Kākāpō may influence their reproductive pattern. However, it remains to be determined whether the steroidogenic potency of these plant extracts is modified when interacting with the unique LBD of native NZ parrots.</p>

Lunar Periodicity in Reproduction of Senatorial Scallop (Chlamys Senatoria Gmelin, 1791) in Asid Gulf, Masbate, Philippines

In Masbate, senatorial scallop Chlamys senatoria is one of the five commercially important species of scallop present in Asid Gulf, but its basic biology is poorly understood in the Philippines. To provide biological information for future conservation and management, the reproductive rhythm of senatorial scallop in relation to lunar phase was investigated from October 2016 to March 2017. Scallops were collected daily from the fishers’ catches and were measured, dissected, and processed for histological analysis; whereas, fecundity and size of eggs (diameter) were also determined. Ecological parameter such as bottom water temperature was monitored during the sampling period. Results showed that C. senatoria is a highly fecund species, which ranges from 8.3 X 105 to 2.1 X 106 oocytes per female and its sizes (oocytes) ranges from 53.8 µm to 72.5 µm while Gonado-somatic index (GSI) ranges from 3.2 to 7.1. Fecundity, egg diameter, and the GSI decreased during new moon (NM) and full moon (FM). GSI indicates that the onset of spawning activity commences during NM and FM. Environmental parameters that were monitored showed significant variations in relation to lunar phase. Spawning of scallop C. senatoria follows a lunar reproductive pattern, which was initiated and influenced by the variations of different factors such as temperature, water amplitude, and light as the effect of lunar/tidal cycles. These findings indicate that reproduction and necessarily spawning in the scallop are related to factors associated with lunar phases. Strategies for managing the resource can be formulated using the temporal dimension of lunar phases.

Reproductive Pattern of Parous Women and The Risk of Cancer in Later Life

We assessed the risk of any and site-specific cancers in a case-control study of parous women living in northeast Scotland in relation to: total number of pregnancies, cumulative time pregnant, age at first delivery and interpregnancy interval. We analysed 6430 women with cancer and 6430 age-matched controls. After adjustment for confounders, women with increasing number of pregnancies had similar odds of cancer diagnosis as women with only one pregnancy. The adjusted odds of cancer diagnosis were no higher in women with cumulative pregnancy time 50–150 weeks compared to those pregnant ≤ 50 weeks. Compared with women who had their first delivery at or before 20 years of age, the adjusted odds ratio (AOR) among those aged 21–25 years was 0.81, 95% CI 0.74, 0.88; 26–30 years AOR 0.77, 95% CI 0.69, 0.86; >30 years AOR 0.63, 95% CI 0.55, 0.73. After adjustment, the odds of having any cancer were higher in women who had an inter-pregnancy interval >3 years compared to those with no subsequent pregnancy (AOR 1.17, 95% CI 1.05, 1.30). Older age at first pregnancy was associated with increased risk of breast and gastrointestinal cancer, and reduced risk of invasive cervical, carcinoma in situ of the cervix and respiratory cancer.