And Hipposcarus Harid (Forsska˚L, 1775) from the Red Sea Coast of Egypt (Family: Scaridae) Laith A
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Journal of the Marine Biological Association of the United Kingdom, 2018, 98(4), 819–828. # Marine Biological Association of the United Kingdom, 2017 doi:10.1017/S0025315416002034 Morphology study of the otoliths of the parrotfish, Chlorurus sordidus (Forsska˚l, 1775) and Hipposcarus harid (Forsska˚l, 1775) from the Red Sea coast of Egypt (Family: Scaridae) laith a. jawad1, kristiaan hoedemakers2, ana l. iba’ n~ez3, yassin a. ahmed4, mohamed a. abu el-regal5 and sahar f. mehanna6 1Flat Bush, Manukau, Auckland, New Zealand, 2Royal Belgian Institute of Natural Sciences (RBINS), Vautierstraat 29, B-1000 Brussels, Belgium, 3Departamento de Hidrobiologı´a, Universidad Auto´noma Metropolitana-Iztapalapa, Av San Rafael Atlixco 186, Col. Vicentina, Me´xico, DF 09340, Me´xico, 4Laboratory of Population Dynamics, Fisheries Division, National Institute of Oceanography and Fisheries, Red Sea Branch, Hurghada, Egypt, 5Marine Science Department, Faculty of Science, Port Said University, Port Said, Egypt, 6Laboratory of Population Dynamics, Fisheries Division, National Institute of Oceanography and Fisheries, Suez Branch, Suez, Egypt In the present study a comparison of the otolith morphology of two species of parrotfish, family Scaridae, collected from the Red Sea coast of Egypt, is conducted to identify the most appropriate taxonomic characters that separate these species. Ontogenetic changes in the otoliths of the two scarid fishes become evident. In the otoliths of Chlorurus sordidus, the following characters are comparable in small-sized adult fishes: otolith width, otolith depth, mesial surface shape, lateral surface shape, shape of sulcus acusticus, column, rostrum and size of rostrum. The otoliths of young adults (GI) C. sordidus differ from the adult ones in 14 out of the 22 characteristics studied. In the otoliths of Hipposcarus harid, the following characters are com- parable in small and large fish: otolith width, otolith depth, mesial and lateral surface shapes, shape of sulcus acusticus, rostrum and size of rostrum. Keywords: morphology, otoliths, SEM, parrotfish, Scaridae, Egypt, Red Sea Submitted 18 November 2016; accepted 28 December 2016; first published online 6 February 2017 INTRODUCTION during prehistoric periods. Smale et al. (1995) described six species of the genus Scarus and of the species Calostomus spi- Chlorurus sordidus is a marine species that sometimes enters nidens, Leptoscarus vaigiensis and Hipposcarus harid, demon- brackish water and lives in association with coral reefs strating the use of otoliths in phylogeny. Rivaton & Bourret (Riede, 2004) at depths from the surface down to 50 m (1999) published images of otoliths of nine species of the (Fischer et al., 1990). It reaches maturity at total length genus Scarus and two species of the genus Cetoscarus from 150 mm (Randall et al., 1990). Similarly, Hipposcarus harid the Indo-Pacific region, showing an innovative technique for has the same mode of life, but lives at a depth range of 1– otolith morphological studies. Tuset et al. (2008) briefly 25 m (Lieske & Myers, 1994). It reaches maturity at 750 mm described the otolith of Saprisoma cretense (Linnaeus, 1758) total length (Randall, 1986). and S. rubripinne (Valenciennes, 1840), showing their super- Otolith morphology has proven useful in phylogenetics iority in phylogenetic studies compared with genetic studies. and palaeoecology, yet such studies for the family Scaridae Baremore & Bethea (2010) used otoliths of Nicholsina usta are scarce. Prominent studies have been conducted in the (Valenciennes, 1840) from the Gulf of Mexico. Lin & Chang Indo-Pacific region, North America, China and the Red Sea. (2012) described the otoliths of seven species of the genus Nolf (1985) provided a diagram of the sagittal otolith of Scarus and species of the genera Calotomus, Chlorurus, Scarus croicensis (¼ S. iseri) (Bloch, 1789). Weisler (1993) Hipposcarus and Leptoscarus from Taiwan, confirming their commented on the importance of the otoliths of Scarus perspi- phylogenetic relations, and Sadighzadeh et al.(2012) gave cillatus (Steindachner, 1879) for archaeological studies, indi- short descriptions of two Scarus species using otoliths morph- cating their significance in determining their communities ology. Nolf (2013) produced otolith diagrams of Nicholsina usta (Valenciennes, 1840) and Scarus croicensis Bloch, 1790, showing their phylogenetic relationships. Except for the Corresponding author: description of the otolith of H. harid from the Red Sea by L.A. Jawad Smale et al. (1995), there is a gap in information on the Email: [email protected] morphology of scarid otoliths from the Red Sea. 819 820 laith a. jawad et al. Distinguishing between C. sordidus and H. harid using external morphological traits is a challenge. Using otolith morphology, however, may prove reliable in making such a distinction. Additionally, otolith morphology may prove a useful supporting tool for archaeology, and palaeoichthyology (Nolf, 1985). The objective of this study is to describe otoliths of juveniles and adults of fish of the family Scaridae. Collections were from the Red Sea, due to the high importance of this species in the region. This work will help resolve the taxonomy among the members of the family Scaridae. MATERIALS AND METHODS The vicinity of Hurghada was chosen as it represents one of Fig. 1. Diagram of the mesial surface of the left otolith of Hipposcarus harid the main fishing grounds for the two study species. illustrating various features of the otolith, which are described in the text. Understanding the asymmetry of the two species is important to show the effect of this phenomenon on the settlement of their larvae in this important fishing ground, as has been shown for other fish species (Battaglia et al., 2010). Specimens of parrotfish were obtained during the fishing season 2012–2013 through monthly sampling from the com- mercial landings. The fish were caught using gill nets of 60– 100 m long with mesh size of 2 (0.25 cm). Standard length (TL) was measured to the nearest 0.1 cm using a digital caliper. The specimens of C. sordidus range from 161 to 250 mm in total length (N ¼ 123). They were placed in seven groups according to their total length: Group I, 161– 170 mm, N ¼ 10; Group II, 171–180 mm, N ¼ 15; Group III, 181–190 mm, N ¼ 20; Group IV, 201– 210 mm, N ¼ 15; Group V, 211– 220 mm, N ¼ 25; Group VI, 231– 240 mm, N ¼ 15; and VII, 241–250 mm, N ¼ 15. The speci- mens of H. harid, which range from 140 to 310 mm in total length (N ¼ 115). Otoliths with obvious evidence of calcite crystallization or other abnormal formations were not consid- ered in this study. Fish otoliths are located on the two sides of the basioccipi- tal bone and separated by a thin septum arising from the mid- Fig. 2. Generalized scheme of the inner surface of saccular otoliths of a ventral ridge of the occipital (Ruck, 1976; Jawad et al., 2007; parrotfish illustrating otolith measurements, described in the text. Jawad, 2008). Otoliths were removed by slicing open the top of the cranium and exposing the brain. After removal of the brain with a sharp scalpel, the otic capsules were separated using image-processing systems (image analysis software and the otoliths gently removed with a pair of fine tweezers. TpsDig2; Rohlf, 2006). Subsequently, the following otolith Later, the otoliths were cleaned with 70% ethanol and stored shape indices were calculated: aspect ratio (OW/OL, %), per- dry in a small glass tube. Scanning electron microscopy was centage of the otolith surface occupied by the sulcus (SS/OS, used to record the morphological characteristics on the %), percentage of the sulcus length occupied by the cauda inner face of the saccular otolith (sagitta). The terminology length (CL/SL, %), percentage of the sulcus length occupied of otolith morphology follows Smale et al.(1995)(Figure 1). by the ostium length (OSL/SL, %), rostrum aspect ratio The otoliths to be used for SEM were air dried and (RW/RL, %), and percentage of the rostrum length occupied mounted on an aluminium stub using double-sided carbon by the otolith length (RL/OL, %). CL/SL and OSL/SL indices tape. Otolith left sagitta were viewed in an ESEM Fei were used for the first time in this work. Quanta 200 at 10.0–20.0 KV. Otolith morphometry RESULTS According to the terminology of Avigliano et al.(2014, 2015), There were ontogenetic changes in the otoliths of the two a number of otolith measurements were recorded. These were scarid fish species. In the otoliths of C. sordidus (Figure 3), otolith length (OL, mm), otolith width (OW, mm), otolith otolith width, otolith depth, mesial surface shape, lateral perimeter (OP, mm), otolith surface (OS, mm2), sulcus perim- surface shape, shape of sulcus acusticus, column, rostrum, eter (SP, mm), sulcus surface (SS, mm2), sulcus length (SL, and size of rostrum were similar. The otoliths of the small mm), cauda length (CL, mm), ostium length (OSL, mm), adults (GI) C. sordidus differed from the large adult ones in rostrum width (RW, mm) and rostrum length (RL, mm) 14 out of the 22 characteristics studied. Detailed descriptions (Figure 2). These measurements were taken for all the otoliths of the otoliths in seven size classes of fish are shown in Table 1. otolith of parrotfish from egypt 821 Fig. 3. (A–J) Otoliths of Chlorurus sordidus. (A) 161 mm TL; (B) 175 mm TL; (C) 183 mm TL; (D) 184 mm TL; (E) 204 mm TL; (F) 210 mm TL; (G) 215 mm TL; (H) 220 mm TL; (I) 240 mm TL; (J) 248 mm TL. In the otoliths of H. harid, otolith width, otolith depth, were two features of the otoliths of GI–GIV of H. harid.This mesial (inner) and lateral surface shapes, shape of sulcus acus- margin became rounded and broadly rounded with a shallow ticus, rostrum and size of rostrum were similar. The otoliths of notch in otoliths of large-sized young fish (GV to GVII).