Mesa-Rodríguez A*, Hernández-Cruz CM, Socorro JA, Fernández-Palacios H, Izquierdo MS and Roo J
Aquaculture Research Group, Science and Technology Park, University of Las Palmas de Gran Canaria, P. O. Box 56, 35200 Telde, Canary Islands, Spain
Received Date: July 28, 2014; Accepted Date: September 12, 2014; Published Date: September 22, 2014
Citation: Mesa-Rodríguez A, Hernández-Cruz CM, Socorro JA, Fernández- Palacios H, Izquierdo MS, et al. (2014) Skeletal Development and Mineralization Pattern of the Vertebral Column, Dorsal, Anal and Caudal Fin Complex in Seriola Rivoliana (Valenciennes, 1833) Larvae. J Aquac Res Development 5:266. doi: 10.4172/2155-9546.1000266
Copyright: 2014 Mesa-Rodríguez A, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Visit for more related articles at Journal of Aquaculture Research & Development
Bone and fins development in Seriola rivoliana were studied from cleared and stained specimens from 3 to 33 days after hatching. The vertebral column began to mineralize in the neural arches at 4.40 ± 0.14 mm Standard Length (SL), continued with the haemal arches and centrums following a cranial-caudal direction. Mineralization of the caudal fin structures started with the caudal rays by 5.12 ± 0.11 mm SL, at the same time that the notochord flexion occurs. The first dorsal and anal fin structures were the hard spines (S), and lepidotrichium (R) by 8.01 ± 0.26 mm SL. The metamorphosis was completed by 11.82 ± 0.4 mm SL. Finally, the fin supports (pterygiophores) and the caudal fins were completely mineralized by 16.1 ± 0.89 mm SL. In addition, the meristic data of 23 structures were provided. Results from the present study might be used as a practical guide for future studies on this field with S. rivoliana or in related species.
Amberjack; Hatchery; Abnormalities; Osteology; Skeleton
Longfin yellowtail, Seriola rivoliana (Valenciennes, 1833) is one of the species proposed for marine aquaculture diversification, mostly due to its fast growth rate [1,2] and worldwide distribution. This species belongs to Carangidae family, along with other popular species like Seriola dumerili (greater amberjack), Seriola lalandi (yellowtail king fish) and Seriola quinqueradiata (Japanese yellowtail). Even though S. rivoliana is commercially produced , studies about its biology are scarce and only few reports on larval rearing have been conducted in Ecuador [4-6], Hawaii  and more recently in the Canary Islands . In contrast, numerous studies of the genus Seriola have been published related to the feeding requirements and nutrition [9-17], reproduction biology [2,18-21] and culture needs [8,22-26].
Regarding osteology studies, previous reports illustrate the bone structure development for other Seriola species. The osteological development of the greater amberjack have been described by different authors [27,28] These authors obtained distinct results probably associated to different environmental conditions and/or the number of samples. Also, the caudal skeleton development of the S. lalandi has been reported . In addition, numerous studies have described the osteological development of other marine finfish species, such as Sparus aurata [30,31], Pagrus pagrus [32,33], Solea senegalensis [34,35], Dentex dentex , Argyrosomus regius , Epinephelus septemfasciatus  or Dicentrarchus labrax .
The objective of the present study was to chart the ossification of the vertebral column, dorsal, anal and caudal fin complex in S. rivoliana larvae cultured under semi intensive system conditions (mesocosms, ). Larvae culture under this type of system usually performed better than those cultures under intensive conditions . The identification of bony structures and mineralization pattern will serve as a tool for future studies, where different factors (zootechnical, nutritional, environmental parameters, etc) may affect the apparition of skeletal abnormalities.
S. rivoliana eggs were obtained from induced spawning (hormonally injection, GnRHa; Sigma-AldrichTM), based on the reported dosage . Larvae were reared under mesocosms rearing system (4.5 eggs.l-1 in two 40 m3 tanks ), kept under natural photoperiod and filtered natural sea water with 37 g/L salinity and temperature of 23.0 ± 0.9°C. Green water technique was used adding live phytoplankton (Nannochloropsis sp.) to maintain a concentration of 250000 cells ml-1 in the rearing tanks. From 2 to 25 days after hatching (dah) rotifers, Brachionus sp., L-strain enriched with DHA Protein Selco (INVETM), were added twice a day (08:00 and 14:00 h). Artemia feeding starts at 15 dah, and were enriched with A1 Easy Selco (INVETM). Weaning protocol included manual feeding from 20 dah (Genma Micro, Skretting TM) to 25 dah and automatic feeding afterwards.
Larval growth was assessed measuring the standard length (SL) of 25 larvae, every 2 days using a profile projector (Nikon V-12A, NIKONTM). A total of 75 specimens were individually stained (3.28 ± 0.15-16.1 ± 0.89 mm SL). To study the bone ossification, all specimens were fixed in 10% buffered formalin, from hatching to 33dah. Fixed larvae were cleared and stained with alizarin red . Larvae were individually examined using stereomicroscopy. Drawings of the different developmental stages were made using the Adobe Photoshop CS3-10.0 (1990-2007 Adobe System Incorporated, United States) directly from digital photographs. Bone description, followed the terminology suggested by different authors [41-43], and their abbreviations, and are illustrated in the Table 1. The angles of the spine were measured from the beginning of the vertebral body to the tip of the spine.
|Vertebral Column||Vertebra centra||Ce|
|Anterior neural zygapophysis||Anz|
|Posterior neural zygapophysis||Pnz|
|Anterior haemal zygapophysis||Ahz|
|Posterior haemal zygapophysis||Phz|
|Anal Fin||Hard Spines||S|
Table 1: Skeletal elements and their abbreviations.
A total of 10 S. rivoliana reared juveniles were soft X-ray monitored (Mod. Senographer-DHR, General electric’s, USA) for meristic counts
In the present study, S. rivoliana vertebral column mineralization was initiated with the neural arches (Na1-Na3) by 4.40 ± 0.14 mm SL (Figure 1A), followed by the haemal arches (Ha1-Ha3) and the cephalic vertebrae (Ce1-4) by 4.74 ± 0.27 mm SL (Figure 1B). The ossification of the vertebral column followed a cranial-caudal direction, being totally ossified by 11.82 ± 0.4 mm SL (Figure 1G). This size marked the end of metamorphosis. The notochord flexion was initiated at 5.12 ± 0.11 mm SL (Figure 1C), at the same time that the caudal complex mineralization was initiated. Initially, urostyle was formed by two independent structures (Ur1-Ur2) that fused by 10.23 ± 0.26 mm SL (Figure 1F). The neural spine (Ns23), the haemal spine (Hs13) and the Ce22-Ce23 were the last structures that mineralized. At 11.82 ± 0.4 mm SL (Figure 1G), four types of articulation processes were mineralized: anterior neural zygapophyses (Anz), posterior neural zygapophyses (Pnz), anterior haemal zygapophyses (Ahz) and posterior haemal zygapophyses (Phz), (Figure 1G).
Figure 1: Development of the vertebral column (A - G) in S. rivoliana (painted areas, mineralized structures). Structures: Ahz, anterior haemal zygapophysis; Anz, anterior neural zygapophysis; Ha, haemal arch; Hs, haemal spine; No, notochord; Na, neural arch; Ns, neural spine; Pp, parapophyse; Plr, pleural rib; Pd, predorsal; Ph, parhypural; Phz, posterior haemal zygapophysis; Pnz, posterior neural zygapophysis; Pr, proximal pterygiophore; R, lepidotrichium; Dr, distal radial; S, hard spine; Ce, vertebral centra; Ur, urostyle.
The vertebral bodies mineralization in the cephalic (without parapophyses) and prehaemal (with parapophyses) region (Ce1-4 and Ce5-10 respectively) proceeded from dorsal to ventral direction and from the surface to internal bone layers (Figures 2A and 2B), whereas in the haemal (with Hs) and caudal region (Ns and Hs modified to support caudal fin complex) the mineralization pattern proceeds in both directions dorsal and ventrally (Ce11-21 and Ce22-23 respectively), joining in the middle of the centra (Figure 2C). Exceptionally, in Ce9 and Ce10, the mineralization of the vertebral bodies differed from other vertebral structures of the prehaemal region, proceeding dorsally first and ventrally later on.
The Na and Ha developed from centrum and fused in the middle, forming the neural and haemal canals with rounded shape, later developing into the Ns and Hs (Figures 2A-2C). The Ns and Hs angle in relation to the vertebral body varied along the vertebral column, increasing in cranial-caudal direction (Figure 1G). The Hs developed according to the angle of the first anal pterygiophore, and decreasing afterward.
The parapophyses (Pp) was first observed with the mineralization of the Pp6-Pp5 by 5.12 ± 0.11 mm SL (Figure 1C). These structures had a caudal-cranial development and were fully ossified at 11.82 ± 0.4 mm SL (Figure 1G). The Pp structures become larger form Ce4 to Ce10.
The pleural ribs (Plr) were observed for the first time at 10.23 ± 0.26 mm SL (Plr1-Plr3) with the caudal development (Figure 1F). Plr4-Plr7 developed at 11.82 ± 0.4 mm SL (Figure 1G). The dorsal ribs (Eb) were first seen at 11.82 ± 0.4 mm SL (Figure 1G), with the mineralization of the Eb1-Eb3, following the caudal development.
Dorsal and anal fins development
The formation and mineralization of the dorsal and anal fins of the long fin yellowtail followed a cranial-caudal direction. The first dorsal fin structures were the hard spines (S) and lepidotrichium (R) by 8.01 ± 0.26 mm SL (Figure 1D), which initiated its mineralization from the base to the tip of the structure. Predorsal bones (Pd1-Pd3) and proximal pterygiophore (Pr) had a dorsal-ventral mineralization pattern (Figure 1F).
In the anal fin, the two hard spines (S1-S2) were first seen at 8.01 ± 0.26 mm SL (Figure 1D), same as the anal lepidotrichia (R) and Pr. The S1-S2 fused into the Pr1 by 9.92 ± 0.84 mm SL (Figure 1E). The S1-S2 and R mineralized from the base to the tip of the structure, whereas the Pr followed a ventral-dorsal pattern (Figure 1F).
Caudal fin development
The first caudal complex structures in mineralized were the upper and lower caudal lepidotrichia (PCR) by 5.12 ± 0.11 mm SL (Figure 3A). Then, hypurals (Hy) initiated their mineralization as fused structures, first Hy1 + Hy2, continues with Hy3 + Hy4 and finally parhypural (Ph) by 5.38 ± 0.11 mm SL (Figure 3B). At the same time, the first upper caudal dermatotrichia (SCR) started to mineralize, following a base-tip mineralization pattern. The last hypural (Hy5) delayed its mineralization to 8.01 ± 0.26 SL (Figure 3C). By 9.92 ± 0.84 mm SL uroneurals (Un1+Un2) arted to mineralize and fused forming a single structure (Uroneural) (Figures 3D and 3E). Finally, the last caudal complex structures in mineralized were the epurals (Ep1-3) by 11.82 ± 0.4 mm SL (Figure 3E).
Meristically, S. rivoliana had a total number of 23 vertebrae (urostyle not included), 23 neural spines, 13 haemal spines, 16 pleural ribs, 12 dorsal ribs and 6 parapophyses. In the dorsal region, 3 predorsal spines, VII+I hard spines and a variable number (30-34) lepidotrichia were identified. Besides, VII hard spine proximal pterygiophores, 30 to 34 distal radial and proximal pterygiophores were also observed. Within the anal region, II+I hard spines and 19-21 lepidotrichia, same number of distal radial and proximal pterygiophores were identified. Finally, in the caudal complex, 1 parahypural, 5 hypurals, 3 epurals, 2 uroneurals, 10+9 caudal lepidotrichia and 10+9 caudad dermatotrichia were observed (Table 2).
|Vertebral column||Caudal fin||Dorsal Fin||Anal Fin|
|Vertebra centra||Urostyle||Neural spine||Haemal spine||Dorsal Ribs||Pleural Ribs||Parapophyses||Hypurals||Parhypural||Epurals||Uroneurals||Lepidotrichia||Dermatotrichia||Predorsal||Hard Spines||Proximal Pterygiophores||Lepidotrichia||Proximal Radial||Distal Radial||Hard Spines||Lepidotrichia||Proximal Radial||Distal Radial|
|S. rivoliana||10+13||1+1||23||13||6+6||8+8||6||5||1||3||1+1||10+9||10+9||3||VII+I||7||30 / 34||30 / 34||30 / 34||II+I||19 / 21||19 / 22||19 / 22||Present Study|
|S. dumerili||10+13||1+1||23||13||6+6||8+8||6||5||1||3||1+1||9+9||12+10||3||VII-VIII||8-Jul||31 / 34||35||32||III||19 / 21||20 / 23||20 / 23|||
|S. fasciata||-||-||-||-||-||-||-||-||-||-||-||-||-||-||VIII+I||-||28 / 31||-||-||II+I||18 / 20||-||-|||
|S. fasciata||-||-||-||-||-||-||-||-||-||-||-||-||-||-||VIII+I||-||28 / 31||-||-||II+I||18 / 20||-||-|||
|S. dumerili||10+13||1||22||13||-||8+8||-||5||1||3||1+1||9+7||12+11||3||VII-VIII||31 / 32||38||-||II-III||20||21||-|||
|T. japonicus||10+14||1||24||14||7+7||10+10||6||5||1||2||1||17||-||3||8||8||27 / 35||27 / 35||27 / 35||II+I||25 / 31||25 / 31||25 / 31|||
Table 2: Meristic counts in different carangid species. ( - ) no data; ( + ) and; ( / ) between.
This study reported for first time S. rivoliana skeletal development and mineralization. The comparison of present results with other species from the same family and genus, such as S. dumerili, suggest some correspondence. Thus,  describes first mineralized structure in the vertebra centra for S. dumerilli at 6.6 mm (NL) while other result for the same specie  identified Neural Spine (NS) and centra at 4.8mm (TL). This pattern agrees with present data for S. rivoliana, where similar mineralization was obtained (4.74 ± 0.27 mm SL). The differences between vertebra centra mineralization timing for S. dumerili could be explained by the different environmental conditions, such as temperature, or rearing protocols applied in those studies . In fact, mineralization pattern is more accurately described when larval growth is used as reference instead of larval age .
Also, the present study showed a similar vertebra centra mineralization timing in comparison with other carangid species, such as Caranx crysos  and Selene setapinnis [45,46], suggesting that some developmental events during mineralization process may be common for many species. For instance, the dorsal flexion at the posterior end of the notochord could be an external indicator of the initiation of the internal column mineralization for this and other species. In fact, these events also occur in other species such as S. aurata larvae (5.7-6.0 mm, SL) , Solea senegalensis larvae (4.7 mm, SL) , Pagrus pagrus larvae (6.0 ± 0.5 mm, TL)  or Argyrosomus regius larvae (5.42-6.01 mm, TL) .
In most Perciforms, the vertebral column follows a bidirectional mineralization pattern (Pagrus major, ; S. aurata, ; Dentex dentex, ; Diplodus sargus, ; Pagrus pagrus, ). However, in S. rivoliana the vertebral column followed a unidirectional mineralization pattern, in agreement with data reported in S. dumerili  and in A. regius .
According to the centrum mineral deposition, three complementary models occur in the vertebral region: in a dorsal-ventral direction (D-V), in a ventral-dorsal direction (V-D) or simultaneously (DVS). In S. aurata  and D. sargus , two centra mineral deposition models occur the first one takes place in a D-V direction from the Ce1 to Ce21 and the second one in a V-D direction in Ce22 and Ce23. In S. rivoliana, the mineralization expands in a D-V direction from Ce1 to Ce23, following the same pattern as S. dumerili between the Ce1-Ce19 . Additionally, S. rivoliana had simultaneously DVS mineralization from Ce8 to Ce23, whereas S. dumerili  presents this simultaneous DVS mineralization pattern from Ce20 to Ce23. Other marine finfish such as A. regius  showed a D-V mineral deposition from Ce1-Ce4, while the remaining vertebrae had simultaneous DVS mineralization.
About to urostyle (Ur) structure of S. rivoliana larvae and other marine finfish such as P. major, C. crysos and S. dumerili [28,44,48], this was formed by the fusion of two elements (Ur1+Ur2). In contrast, at least three elements were necessary to form this structure in S. lalandi . The results of the present study suggest that the fusion of different structures to form the urostyle is nonspecific of the genus Seriola sp.
The development of the parapophyses (Pp) of S. rivoliana followed a caudal-cranial development, in concordance with S. dumerili  and many other perciforms such as S. aurata , Lates calcarifer , Diplodus sargus  or Pagrus pagrus . The correlation between the present study and many other marine finfish suggest that the developmental patter for the parapophyses may be common in perciforms .
In many marine finfish species, the mineralization of the anal and posterior dorsal fins starts prior to the anterior dorsal fin [31,32,50-52]. Unlike this developmental pattern, but in accordance with S. dumerili , S. rivoliana dorsal and anal structures followed a cranial-caudal development, developing the anterior dorsal fin prior to posterior dorsal fin. However, despite S. rivoliana and S. dumerili had the same developmental pattern in dorsal, anal and caudal fins; some differences in structures development have been observed. For instance, in S. rivoliana, firsts structures in mineralized were hard spines (S) and lepidotrichium (R) (present study), whereas in S. dumerili  the dorsal fins development starts with the mineralization of the proximal pterygiophore.
During the process of the caudal complex mineralization of S. rivoliana, the fusion of hypurals (Hy1+Hy2 and Hy3+Hy4) was observed. This developmental pattern is common in other carangid species such as S. lalandi , S. setapinnis , C. crysos  and S. dumerili [27,28]; as well as other perciforms such as Coryphaena equiselis , P. major , S. aurata  and D. dentex . The development of three distinct structures (Hy1+Hy2, Hy3+Hy4, Hy5) could remain as a characteristic of carangids and Coryphaena .
In the present study, the development of three epurals and two uroneurals were observed. The number of epurals in the caudal complex of Carangoidei species varies between species : 3 epurals in S. dumerili , between 3-4 epurals (usually 3 epurals) in S. lalandi , 2 independent epurals that fused during ontogeny in C. equiselis  and 3 epurals for S. rivoliana (present study). Other authors  considered that the presence of uroneurals is a characteristic of the Teleost. The presence of two uroneurals in S. rivoliana caudal fin complex is in concordance with other species from the same genus such as S. lalandi  and S. dumerili .
Meristically, the vertebral column of longfin yellowtail (S. rivoliana) was characterized in this study. Similar results have been reported in S. dumerili . Nevertheless, in other carangid species such as S. setapinnis , Hemicaranx amblyrhynchus  or Trachurus japonicas  a total number of 24 vertebral structures were observed, and the first haemal arch was observed at the 10th vertebra  instead of at the 11th vertebrae in S. dumerili [27,28] and S. rivoliana (present study), indicating that this could be a conserved feature among the genus Seriola (Table 2).
Concerning the caudal complex, S. rivoliana presented similar results than those observed in S. lalandi , S. setapinnis , C. crysos  and S. dumerili [27,28], although the number of caudal fin rays is a characteristic for each species. Thus, in this study, S. rivoliana had 10+9 caudal lepidotrichia and 10+9 caudad dermatotrichia, while 9+9 caudal lepidotrichia and 11-13+10 caudal dermatotrichia where reported in S. dumerili  or 9+8 caudal lepidotrichia and 6+5 caudad dermatotrichia were observed in S. setapinnis .
Results from the present study might be used as practical guide for future studies on this field with S. rivoliana or in related species
This study was funded by the Agencia Canaria de Investigación, Innovación y Sociedad de la Información (ACIISI) and Fondo Europeo de Desarrollo Regional (FEDER) through the program “Mejora de las técnicas de cría de larvas de (Seriola rivoliana): Determinación de requerimientos de ácidos grasos esenciales en su etapa larvaria y optimización de la secuencia alimentaria (METCSERProID20100094)”.