DOCSLIB.ORG

First Record of Sex Reverses in Two Indo-Pacific Mytildes (Brachidontes Variabilis and Modiolus Arcutulus) in the Great Bitter L

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
First Record of Sex Reverses in Two Indo-Pacific Mytildes (Brachidontes Variabilis and Modiolus Arcutulus) in the Great Bitter L International Journal of Fisheries and Aquatic Studies 2017; 5(6): 121-126 E-ISSN: 2347-5129 P-ISSN: 2394-0506 (ICV-Poland) Impact Value: 5.62 First record of sex reverses in two Indo-Pacific mytildes (GIF) Impact Factor: 0.549 IJFAS 2017; 5(6): 121-126 (Brachidontes variabilis and Modiolus arcutulus) in the © 2017 IJFAS www.fisheriesjournal.com Great Bitter Lake, Egypt Received: 18-09-2017 Accepted: 19-10-2017 Kandeel El-Sayed Kandeel Kandeel El-Sayed Kandeel Department of Zoology, Faculty of Science, Fayoum University, Abstract 63514 Fayoum, Egypt Two Indo-Pacific mytilides; Brachidontes variabilis and Modiolus arcuatulus, were collected monthly from the Great Bitter Lake during the period from December 2015 to March 2016. The two species are dioecious. Females significantly outnumbered males. X2 test = 8.042 (P < 0.005) and 7.100 (P < 0.01) for B. variabilis and M. arcuatulus, respectively. Hermaphroditic individuals were found in each species. The present study suggests, perhaps surprisingly, the presence of sex reverse for the first time in the two mytilides in the Great Bitter Lake. This characteristic is not progressive but limited to a very few individuals. The rapid transition of the gonads from one cycle to the next in spent stage has been suggested as the reason for the presence of low frequencies of hermaphroditism. Keywords: Sex ratio, Sex reverse, Brachidontes variabilis, Modiolus arcutulus, Great Bitter Lake, Egypt 1. Introduction The Mytilidae is a family of considerable antiquity dating back to the Devonian era and includes many important genera such as Mytilus, Modiolus, and Brachidontes [1]. Mussels belonging to this family dominate in much of the low and mid intertidal regions in temperate [2] seas of the northern and southern hemispheres . They are suspension feeders and are held in place by strong byssus threads. Mussel larvae settlement and firm attachment of young mussels are facilitated by rough textured rock surfaces which reduce the effective current velocity. Many man-made structures, the hulls of ships, cooling systems of power plants, surfaces of docks, piers, buoys, mariculture cages and offshore platforms all attract diverse communities of sessile fauna and flora to settle on them. These communities are known in general as “fouling communities”. Fouling communities consist of a mixture of algae and suspension-feeding invertebrates including mussels. Fouling on ships increases drag, thereby reducing speed, and growth of barnacles may increase the possibility of corrosion. Growth of fouling organisms on offshore buoys also increases drag and may eventually result in the buoy dipping below the water surface in strong currents. Military vessels, water treatment plants, water intake pipes and cooling water systems of industrial plants and power stations often experience fouling problems caused by mussels in Suez Canal water system (pers. observ.) and many parts of the world [3-5]. Settlement and growth of the mussels on these utilities result in blockage of free flow of water in the conduits and clogging of condenser tubes. With the opening of the Suez Canal in 1869, the waters of the subtropical Mediterranean and the tropical Red Sea came into direct contact. A considerable number of bivalve species of the Red Sea and Mediterranean migrated to the Suez Canal lakes. This migration resulted in a mixed population of bivalves from two different marine environments. Por [6] studied the theory of species migration through the Suez Canal and suggested the term “Lessepsian migration” for the movement of species from the Red Sea to the Mediterranean. The number of bivalve species migrated from the Red Sea to the Suez Canal lakes (Indo-Pacific species) is higher than those moved from the Mediterranean in the opposite direction [7-8]. Fouda and Correspondence Abou-Zied [7] recorded 35 species of Indo-Pacific bivalves including 4 species of mytilids; Kandeel El-Sayed Kandeel Department of Zoology, Faculty Brachidontes variabilis (Krauss, 1848), Arcuatulus arcuatulus (=Modiolus arcuatulus, Barash of Science, Fayoum University, and Danin, 1972), Septifer bilocularis Linnaeus 1758 and Modiolus auriculatus (Krauss, 63514 Fayoum, Egypt 1848). ~ 121 ~ International Journal of Fisheries and Aquatic Studies The available information about the ecology and biology of December 2015 to March 2016. Collected samples were kept Indo-Pacific bivalves in the Suez Canal lakes are very limited in labeled containers filled with 6% formaldehyde-seawater [9]. Thus, the main aim of this work is to investigate sex ratio solution and then transported to the laboratory. Some and its variation among different size groups of two Indo- specimens were fixed in Bouin’s solution for histological Pacific mytilids; Brachidontes variabilis (Krauss, 1848) and preparation. Modiolus arcutulus, Barash and Danin 1972, in the Great In the laboratory, shell lengths (SL); (maximum distance on Bitter Lake. The possibility of the presence of sex reverses in the anterior-posterior axis) of the entire specimens were the two mussels. measured to the nearest 0.1 mm by using a Vernier caliper. Smears of the gonadal tissue from each animal collected was 2. Materials and methods examined microscopically to confirm its sex. Sex ratio Brachidontes variabilis (Krauss, 1848) sampling was carried expressed as the number of females per males (M: F) was out by quadrates; each measuring 10 x 10 cm. Mussels determined. Statistically significant deviations from the inhabiting the area of the quadrates were scraped from the expected sex ratio of 1:1 were assessed by a Chi-square (X2) rock surface using a sharp knife. For Modiolus arcutulus; analysis with one degree of freedom [10]. Gonads of mature Barash and Danin, 1972, core samples of sediment were taken individuals fixed in Bouin’s solution were dissected, from the surface of the mussel bed using 14 cm diameter dehydrated in alcohol, cleared in xylene, embedded in circular plastic pipe. Samples were washed out carefully in paraffin wax and sectioned (6 – 8 µm) at a standard point (Fig situ through one mm size sieve. Collection of samples was 2A & 3A). Tissue sections were stained in Ehrlich’s carried out from the Great Bitter Lake during the period from hematoxylin and Eosin Y following Howard and Smith [11]. Fig 1: Map of the Suez Canal showing mussel collection area; Great Bitter Lake. ~ 122 ~ International Journal of Fisheries and Aquatic Studies Fig 2: B. variabilis, (A) Gross anatomy after the removal of the right mantle lobe, the right ctenidium and the right labial palps. The line shows the location where histological cross-sections were taken place. (B) Slide microprojector drawing of a transverse section showing the position of the gonad. Abyssal threads (AT), Digestive diverticula (DD), Female follicles (FF), Foot (F), Gill lamella (GL), Inner demibranch (ID), Ligament (L), Male follicles.(MF), Mantle cavity (MC), Mantle lope (ML), Mantle margin (MM), Outer demibranch (OD), Posterior adductor mussel (PA), Rectum (R), Right mantle (RM),Ventral part of visceral mass (VP) and Visceral mantle (VM). triangular lobe in the midline between the gills (Fig 2 A & B). This lobe was not found in M. arcuatulus (Fig 3 A & B). Gonads also extend into both left and right mantle lobes. The number of follicles present in transverse sections of the mantle varies considerably according to the state of gonad development. 3.2 Gonad organization Males and females are similar in gross anatomy of their reproductive system. Gonads are ramified organs composed of numerous follicles, which are of various shapes. Most of the spaces between the follicles (interfollicular spaces) are filled with connective tissue which is well developed in B. variabilis and scanty in M. arcuatulus (Fig 4). The follicles contain germ cells at different stages of development depending upon the reproductive condition of the species (Fig 5 & 6). Oocytes in either the early or late developmental stage arise along the walls of the ovarian follicles Testicular follicles showed spermatogenic cells; spermatogonia, spermatocytes, spermatids and sperms in the center of the follicles. In B. variabilis and M. arcuatulus the formation of germ cells follows the same basic pattern of other pelecypods [12-15]. The gametes arise by proliferation from the wall of the follicles and when they become mature, they were pushed towards the center of the follicles. Fig 3: M. arcuatulus, (A) Gross anatomy as seen from the right side. The line shows the location where histological cross-sections were taken place. (B) Slide microprojector drawing of a transverse section showing the position of the gonad. Abyssal threads (AT), Digestive diverticula (DD) Female follicles (FF), Foot (F), Gill lamella (GL), Inner demibranch (ID), Ligament (L), Male follicles (MF), Mantle cavity (MC), Mantle lope (ML), Mantle margin (MM), Outer demibranch (OD), Posterior adductor mussel (PA), Rectum (R), Right mantle (RM), Ventral part of visceral mass (VP) and Visceral mantle (VM). 3. Results 3.1 Gonad position The gonads of Brachidontes variablis and Modiolus arcuatulus enclose the digestive diverticula and may intersperse among other regions of the visceral mass depending on the maturity state of the species. In B. variabilis, the ventral part of the visceral mass posterior to the foot was entirely filled with gonadal materials forming a ~ 123 ~ International Journal of Fisheries and Aquatic Studies Fig 4: Histological photomicrographs of gonad in spent stage for B. variabilis (A) and M. arcutulus (B). Follicle wall (FW), Fig 6: Histological photomicrographs of hermaphrodite gonad of M. Interfollicular connective tissue (IFC), Interfollicular space (IFS), arcuatulus. Feale follicle (FF), Gill-fillaments (GF), Interfollicular Lumen (L) and Nutritive inclusion (NI). space (IFS), Lumen (L), Male follicle (MF), Growing oocytes (GO) and Spermatozoa (SZ). 3.3 Hermaphroditism Microscopic examination of B. variabilis and M. arcuatulus revealed the presence of hermaphrodite gonads. Male and female gonadal follicles were found in different regions of the same gonad (Fig 5 & 6).There is no boundary between the two follicles. Each follicle is either all male or all female; the absence of ambisexal follicles.
Load more

Recommended publications
  • Prolonged Lag in Population Outbreak of an Invasive Mussel: a Shifting-Habitat Model
    Biological Invasions 6: 347–364, 2004. © 2004 Kluwer Academic Publishers. Printed in the Netherlands. Prolonged lag in population outbreak of an invasive mussel: a shifting-habitat model Gil Rilov1,3,∗, Yehuda Benayahu2 & Avital Gasith1 1Institute for Nature Conservation Research, 2Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat-Aviv, Tel Aviv 69978, Israel; 3Current Address: School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 1, New Zealand; ∗Author for correspondence (e-mail: [email protected]; fax: +64-3-3642024) Received 28 May 2002; accepted in revised form 9 December 2003 Key words: bioinvasions, Brachidontes pharaonis, Israel, lag-time, Lessepsian migration, Mediterranean Sea, mussel, rocky shore Abstract Biological invasions pose a great threat to the integrity of natural communities. Some invasive species demonstrate a population explosion shortly after arrival while in other cases a prolonged lag between arrival and population outbreak is evident. This paper describes a case of a prolonged lag and explores the possible mechanism for this lag. The Red Sea mussel Brachidontes pharaonis, a Lessepsian migrant, was first recorded in the Mediterranean seven years after the opening of the Suez Canal in 1869. Since then it spread along the Israeli coast and as far northwest as Sicily. Studies conducted in the late 1970s, when B. pharaonis was still rare, predicted that it would not establish dense populations along the Israeli coast and would not outcompete the indigenous mussel Mytilaster minimus, although it has strong negative effects on survival and growth of the native species. It was attributed to the invader’s low intrinsic rate of increase relative to that of the native species, and to strong density-independent mortality generated by exposure to high wave action and sedimentation.
    [Show full text]
  • Alien Species in the Mediterranean Sea by 2010
    Mediterranean Marine Science Review Article Indexed in WoS (Web of Science, ISI Thomson) The journal is available on line at http://www.medit-mar-sc.net Alien species in the Mediterranean Sea by 2010. A contribution to the application of European Union’s Marine Strategy Framework Directive (MSFD). Part I. Spatial distribution A. ZENETOS 1, S. GOFAS 2, M. VERLAQUE 3, M.E. INAR 4, J.E. GARCI’A RASO 5, C.N. BIANCHI 6, C. MORRI 6, E. AZZURRO 7, M. BILECENOGLU 8, C. FROGLIA 9, I. SIOKOU 10 , D. VIOLANTI 11 , A. SFRISO 12 , G. SAN MART N 13 , A. GIANGRANDE 14 , T. KATA AN 4, E. BALLESTEROS 15 , A. RAMOS-ESPLA ’16 , F. MASTROTOTARO 17 , O. OCA A 18 , A. ZINGONE 19 , M.C. GAMBI 19 and N. STREFTARIS 10 1 Institute of Marine Biological Resources, Hellenic Centre for Marine Research, P.O. Box 712, 19013 Anavissos, Hellas 2 Departamento de Biologia Animal, Facultad de Ciencias, Universidad de Ma ’laga, E-29071 Ma ’laga, Spain 3 UMR 6540, DIMAR, COM, CNRS, Université de la Méditerranée, France 4 Ege University, Faculty of Fisheries, Department of Hydrobiology, 35100 Bornova, Izmir, Turkey 5 Departamento de Biologia Animal, Facultad de Ciencias, Universidad de Ma ’laga, E-29071 Ma ’laga, Spain 6 DipTeRis (Dipartimento per lo studio del Territorio e della sue Risorse), University of Genoa, Corso Europa 26, 16132 Genova, Italy 7 Institut de Ciències del Mar (CSIC) Passeig Mar tim de la Barceloneta, 37-49, E-08003 Barcelona, Spain 8 Adnan Menderes University, Faculty of Arts & Sciences, Department of Biology, 09010 Aydin, Turkey 9 c\o CNR-ISMAR, Sede Ancona, Largo Fiera della Pesca, 60125 Ancona, Italy 10 Institute of Oceanography, Hellenic Centre for Marine Research, P.O.
    [Show full text]
  • A Study on Assemblage of Invertebrates Inhabiting Rocky Shores Within the Port-Limit of Port-Louis, Mauritius
    Journal of Coastal Development ISSN : 1410-5217 Volume 14, Number 2, February 2011 : 159 - 167 Accredited : 83/Dikti/Kep/2009 Original Paper A STUDY ON ASSEMBLAGE OF INVERTEBRATES INHABITING ROCKY SHORES WITHIN THE PORT- LIMIT OF PORT- LOUIS, MAURITIUS Julia Charles1), Chandani Appadoo2), Asha Poonyth2) 1) Department of Biosciences, Faculty of Science, University of Mauritius, Reduit, Mauritius, Chapel Lane, L’Escalier, Mauritius 2) Department of Biosciences, Faculty of Science, University of Mauritius, Reduit, Mauritius 3) Mauritius Oceanography Institute, France Centre, Quatre Bornes, Mauritius Received : January, 3, 2011 ; Accepted : January, 31, 2011 ABSTRACT Rocky shores provide an important habitat for marine organisms. This study aimed at providing baseline data on assemblage of organisms on rocky shores within the port-limit of Port-Louis, Mauritius. Four rocky shores, with three at Pointe aux Sables (La Pointe1, La Pointe2, and Petit Verger) and one at Baie du Tombeau were studied from October 2007 to February 2008. On each site three stations, located at intervals of 2m, with an area of 40m2 each were set up. Intertidal organisms were hand-collected within forty-eight, 1m2 quadrat for invertebrates. Observations of 16,061 specimens led to identification of 30 faunal species belonging mostly to phyla Mollusca and Arthropoda. Mean total abundance of invertebrates per 1m2 varied from 729.22±173.07 at la Pointe2 to 143.97±11.43 at Baie du Tombeau. The gastropod, Planaxis sulcatus was the most abundant species at La Pointe1 and Petit Verger with mean abundance of 196.86±179.71 and 168.10±113.44 per 1m2 respectively. The bivalve, Modiolus auriculatus was the dominant species with mean abundance of 673.33±762.04 per 1m2 at La Pointe2 and Nerita punctata was most abundant (39.41±57.35 per 1m2) at Baie du Tombeau.
    [Show full text]
  • Находка Modiolus Nipponicus (Oyama, 1950) (Bivalvia: Mytilidae) В Российских Водах Японского Моря К.А
    Бюллетень Дальневосточного The Bulletin of the Russian малакологического общества Far East Malacological Society 2017, вып. 21, № 1/2, с. 163–177 2017, vol. 21, N 1/2, pp. 163–177 Находка Modiolus nipponicus (Oyama, 1950) (Bivalvia: Mytilidae) в российских водах Японского моря К.А. Лутаенко, А.А. Кепель Национальный научный центр морской биологии ДВО РАН, Владивосток, 690041, Россия e-mail: [email protected] Пустая раковина Modiolus nipponicus (Oyama, 1950) (Bivalvia: Mytilidae) обнаружена в юго- восточной части залива Петра Великого Японского моря, вблизи российско-северокорейской гра- ницы, на полистирольном плавнике, что является первой находкой этого вида в российских водах. Японский модиолус, являясь тропическо-субтропическим видом, обитает в северной части своего ареала в южнокорейских и японских водах Японского моря (на север до северного Хонсю) и может считаться потенциально инвазивным видом в российский сектор моря. Приведены описание, деталь- ная синонимия, таксономические и биогеографические замечания и фотоиллюстрации этого и близ- ких видов. Ключевые слова: двустворчатые моллюски, Modiolus nipponicus (Oyama, 1950), потенциаль- ный вселенец, Японское море, Россия. Finding of Modiolus nipponicus (Oyama, 1950) (Bivalvia: Mytilidae) in Russian waters of the Sea of Japan K.A. Lutaenko, A.A. Kepel National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok 690041, Russia e-mail: [email protected] A shell of Modiolus nipponicus (Oyama, 1950) (Bivalvia: Mytilidae) was found for the first time in Russian waters of the Sea of Japan, in south-western Peter the Great Bay, near the Russian-North Korean border, as attached to a beach-drifted plastic litter. This species, being a tropical-subtropical, in its northern geographical range inhabits the South Korean and Japanese waters (north to northern Honshu) of the Sea of Japan and is regarded as a potentially invasive mollusk to the Russian coast.
    [Show full text]
  • (Bivalvia: Mytilidae) Reveal Convergent Evolution of Siphon Traits
    applyparastyle “fig//caption/p[1]” parastyle “FigCapt” Zoological Journal of the Linnean Society, 2020, XX, 1–21. With 7 figures. Downloaded from https://academic.oup.com/zoolinnean/advance-article/doi/10.1093/zoolinnean/zlaa011/5802836 by Iowa State University user on 13 August 2020 Phylogeny and anatomy of marine mussels (Bivalvia: Mytilidae) reveal convergent evolution of siphon traits Jorge A. Audino1*, , Jeanne M. Serb2, , and José Eduardo A. R. Marian1, 1Department of Zoology, University of São Paulo, Rua do Matão, Travessa 14, n. 101, 05508-090 São Paulo, São Paulo, Brazil 2Department of Ecology, Evolution & Organismal Biology, Iowa State University, 2200 Osborn Dr., Ames, IA 50011, USA Received 29 November 2019; revised 22 January 2020; accepted for publication 28 January 2020 Convergent morphology is a strong indication of an adaptive trait. Marine mussels (Mytilidae) have long been studied for their ecology and economic importance. However, variation in lifestyle and phenotype also make them suitable models for studies focused on ecomorphological correlation and adaptation. The present study investigates mantle margin diversity and ecological transitions in the Mytilidae to identify macroevolutionary patterns and test for convergent evolution. A fossil-calibrated phylogenetic hypothesis of Mytilidae is inferred based on five genes for 33 species (19 genera). Morphological variation in the mantle margin is examined in 43 preserved species (25 genera) and four focal species are examined for detailed anatomy. Trait evolution is investigated by ancestral state estimation and correlation tests. Our phylogeny recovers two main clades derived from an epifaunal ancestor. Subsequently, different lineages convergently shifted to other lifestyles: semi-infaunal or boring into hard substrate.
    [Show full text]
  • In the Red Sea, Egypt
    International Journal of Ecotoxicology and Ecobiology 2016; 1(3): 72-75 http://www.sciencepublishinggroup.com/j/ijee doi: 10.11648/j.ijee.20160103.12 Observations on the Population Characters of Eared Horse Mussel, Modiolus auriculatus (Krauss, 1848) in the Red Sea, Egypt Fatma A. Abdel Razek 1, *, Salah E. Abdel-Gaid 2, Hamdy O. Ahmed 1, El Sayed A. E. Hamed 3, Mohamed M. Abu-Zaid 2, Tarek A. A. Mohammed 3 1Department of Aquaculture, National Institute of Oceanography & Fisheries, Alexandria, Egypt 2Department of Zoology, Faculty of Science, Al-Azhar University, Cairo, Egypt 3Department of Aquaculture, National Institute of Oceanography & Fisheries, Hurghada, Egypt Email address: [email protected] (F. A. A. Razek ) *Corresponding author To cite this article: Fatma A. Abdel Razek, Salah E. Abdel-Gaid, Hamdy O. Ahmed, El Sayed A. E. Hamed, Mohamed M. Abu-Zaid, Tarek A. A. Mohammed. Observations on the Population Characters of Eared Horse Mussel, Modiolus auriculatus (Krauss, 1848) in the Red Sea, Egypt. International Journal of Ecotoxicology and Ecobiology. Vol. 1, No. 3, 2016, pp. 72-75. doi: 10.11648/j.ijee.20160103.12 Received : June 25, 2016; Accepted : July 22, 2016; Published : September 5, 2016 Abstract: The population analysis of 240 Modiolus auriculatus individuals collected from the Red Sea showed that its size ranged from 1.36 cm to 6.02 cm in shell length. During spring and summer seasons, most abundant shell size groups of average shell length 4.0 cm, 5.0 cm and 6.0 cm were observed. While during autumn and winter seasons the groups of 1.5 cm, 2.0 cm and 2.5 cm were found in the population.
    [Show full text]
  • Annotated List of Marine Alien Species in the Mediterranean with Records of the Worst Invasive Species
    Mediterranean Marine Science Volume 6/2, 2005, 63-118 Annotated list of marine alien species in the Mediterranean with records of the worst invasive species A. zeNETOS1, M.E. ÇINAR2, M.A. pANcucci - pApAdopoulou1, J.g. hARMeliN3, g. fuRNARi4, f. ANdAloRo5, N. bellou1, N. STREFTARIS1 and h. zibRoWiuS3 1 Hellenic Centre for Marine Research (HCMR), Institute of Oceanography, Anavissos 19013, Attica, Greece 2 Ege University, Faculty of Fisheries, Department of Hydrobiology, 35100 Bornova, Izmir, Turkey 3 Centre d’Océanologie de Marseille, UMR 6540 DIMAR, Station Marine d’Endoume, 13007 Marseille, France 4 Università di Catania, Dipartimento di Botanica, Via A. Longo 19, 95125 Catania, Italy 5 Istituto Centrale per la Ricerca Scientifica e Tecnologica Applicata al Mare (ICRAM), Via E. Amari 124 90139 Palermo, Italy e-mail: [email protected] Abstract This collaborative effort by many specialists across the Mediterranean presents an updated an- notated list of alien marine species in the Mediterranean Sea. Alien species have been grouped into six broad categories namely established, casual, questionable, cryptogenic, excluded and invasive, and presented in lists of major ecofunctional/taxonomic groups. The establishment success within each group is provided while the questionable and excluded records are commented in brief. A total of 963 alien species have been reported from the Mediterranean until December 2005, 218 of which have been classified as excluded (23%) leaving 745 of the recorded species as valid aliens. Of these 385 (52%) are already well established, 262 (35%) are casual records, while 98 species (13%) remain “questionable” records. The species cited in this work belong mostly to zoobenthos and in par- ticular to Mollusca and Crustacea, while Fish and Phytobenthos are the next two groups which prevail among alien biota in the Mediterranean.
    [Show full text]
  • Exotic Molluscs in the Mediterranean Basin: Current Status and Perspectives
    Oceanography and Marine Biology: an Annual Review 2003, 41, 237–277 © R.N. Gibson and R.J.A. Atkinson, Editors Taylor & Francis EXOTIC MOLLUSCS IN THE MEDITERRANEAN BASIN: CURRENT STATUS AND PERSPECTIVES SERGE GOFAS1 & ARGYRO ZENETOS2 1Departamento de Biologia animal, Facultad de Ciencias – E-29071 Málaga, Spain e-mail: [email protected] 2National Centre for Marine Research, P.O. Box 712, Mavro Lithari, GR-19013 Anavissos, Greece e-mail: [email protected] Abstract An updated synthesis is presented for the records of introduced Mollusca in the Mediterranean basin. The rationale for taking molluscan records as significant is discussed. The Mediterranean Sea, with some 1800 native species of Mollusca, currently houses 139 exotic species, of which 85 form established populations, 52 are aliens recorded once or twice, and two are questionable. Ten species (the gastropods Cerithium scabridum, Rhinoclavis kochi, Strom- bus persicus and Bursatella leachi and the bivalves Pinctada radiata and Brachidontes pharao- nis in the eastern Mediterranean, the gastropod Rapana venosa and the bivalves Anadara inaequivalvis, Musculista senhousia, and Xenostrobus securis in the northern Adriatic and the western Mediterranean lagoons) are locally invasive. The bulk of the introduced species (118 species, of which 70 are established, 46 aliens, and two questionable) are species of Indo–Pacific origin found mainly in the eastern basin of the Mediterranean. Among these species, some which live in the Suez Canal are most likely to have spread by their own means through this waterway (these are the “lessepsian immigrants” in the most restricted sense). For other species, the intervention of transport by ship hulls or ballast water can be suspected.
    [Show full text]
  • Larval Recruitment of the Tropical Mussel Modiolus Philippinarum (Bivalvia: Mytilidae) in Seagrass Beds
    VENUS 65 (3): 203-220, 2006 Larval Recruitment of the Tropical Mussel Modiolus philippinarum (Bivalvia: Mytilidae) in Seagrass Beds Hiroyuki Ozawa*, Taeko Kimura** and Hideo Sekiguchi Faculty of Bioresources, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507, Japan; **[email protected] Abstract: The tropical mussel Modiolus philippinarum is common and abundant in seagrass beds in Okinawa Island, southernmost Japan, and is commercially important to local fishermen. In order to elucidate the mechanisms that maintain the difference in density between benthic populations of the mussel within and outside seagrass beds, we monitored temporal variations in densities of the mussel at different developmental stages (planktonic larvae; new settlers; small and large individuals) within and outside seagrass beds in Okinawa Island over one year. Based on these data, the difference in larval density was not significant, but there were significant differences between densities of new settlers (shell length<250 μm), small individuals (250 μm≦shell length<1.0 mm) and large individuals (shell length≧1.0 mm), within and outside seagrass beds. Cohort separation was applied to data for shell length distributions of new settlers and small and large individuals, and revealed that larvae mainly settled in July to August. New settlers grew up to about 20 mm in shell length in their first year; their mortality was constant and/or low once individuals had attained shell lengths of about 300 μm. These facts indicates that the much higher density of benthic populations of the mussel within seagrass beds may be determined at and/or shortly following larval settlement, though details of the mechanisms driving the above difference are not yet identified.
    [Show full text]
  • Aspects on the Reproduction of Eared Horse Mussel, Modiolus Auriculatus (Krauss, 1848) in Red Sea, Egypt
    Egyptian Journal of Aquatic Research (2014) 40, 191–198 HOSTED BY National Institute of Oceanography and Fisheries Egyptian Journal of Aquatic Research http://ees.elsevier.com/ejar www.sciencedirect.com FULL LENGTH ARTICLE Aspects on the reproduction of eared horse mussel, Modiolus auriculatus (Krauss, 1848) in Red Sea, Egypt Fatma A. Abdel Razek a,*, Salah E. Abdel-Gaid b, Mohamed M. Abu-Zaid b, Tarek A. Aziz a a National Institute of Oceanography & Fisheries, NIOF, Egypt b Faculty of Science, Al-Azhar University, Cairo, Egypt Received 8 April 2014; accepted 28 April 2014 Available online 4 July 2014 KEYWORDS Abstract The reproductive cycle of the eared horse mussel, Modiolus auriculatus, was followed for Reproductive cycle; one year from February, 2011 to January, 2012 based on 240 individuals collected from Hurghada, Eared horse mussel; north coast of Red Sea, Egypt. The gonadal maturation of M. auriculatus was examined by means Modiolus auriculatus; of macroscopic and histological preparations of the mantle. Annual cycle with periods of growth, Red Sea maturity and discharge of gonadic products occurs simultaneously in both sexes. Ripe individuals were observed throughout the year. The largest number of spawning for the individuals occurred from March to June and July for the population. So, it was clear to identify one heavy spawning period for this species. Sexation of M. auriculatus did not differ significantly from 1:1. Sexes were distinguishable in all individuals at the ripe stage with a shell length greater than 3.00 cm. A direct positive correlation was observed between gonad index and water temperature. ª 2014 Hosting by Elsevier B.V.
    [Show full text]
  • Pdf (803.71 K)
    Al Azhar Bulletin of Science Vol. 29, No. 2 (December), 2018, pp. 11-24 ASPECTS OF REPRODUCTIVE BIOLOGY OF THE MUSSEL, BRACHIDONTES PHARAONIS (FISCHER, 1870) (MYTILIDAE:BIVALVIA: MOLLUSCA) FROM THE NORTHWESTERN COAST OF SUEZ GULF, EGYPT El-Sayed, A. A.M.1; El-Mekawy, H. A.1; Al-Hammady, M. A.2; Owen, N.A.3and Nassef, A.M.1 1- Faculty of Science, Al-Azhar University, Cairo, Egypt, 2- National Institute of Oceanography and Fisheries, Red Sea, Hurghada, Egypt, 3- Faculty of Science, Sabratha University, Sabratha, Libya. E- Mail: [email protected] [email protected] ABSTRACT Reproductive cycle of the two populations of Brachidontes pharaonis (Mytilidae: Bivalvia: Mollusca)at Adabia and Ain Sokhna (northern western coast of the Suez Gulf), was studied during the period from January to December 2014. The present results showed that sex is separated in this species, but the microscopic examinations are necessary for determination of gonads in both sexes. The first appearance for gonads was observed in males and females at 6.3and 6.5 mm shell length, respectively. However, the largest immature individuals reach 8.6 mm shell length. The overall sex ratio indicated to over dominant females at both sites, with 1:1.57 (males: females) at Adabia, increased slightly to 1:1.81 (males: females) at Ain Sokhna, with 2 statistical significant differences (X = 8.33 and 5.14 significant at P<0.001 and P<0.05), respectively. Gonads of both sexes appeared scattered within mantle tissues at both left and right sides of the animal. Mature male testes have whitish or creamy color, while females ovaries are more conspicuous, appeared lobulated and composed of a large numbers of oogenic follicles occupying most of the mantle depending on stages of egg maturation.
    [Show full text]
  • Brachyura: Pinnotheridae), with an Updated List of Symbiont-Host Associations
    diversity Review A Review of the Ecomorphology of Pinnotherine Pea Crabs (Brachyura: Pinnotheridae), with an Updated List of Symbiont-Host Associations Werner de Gier 1,2,* and Carola Becker 3 1 Taxonomy and Systematics Group, Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, The Netherlands 2 Groningen Institute for Evolutionary Life Sciences, University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands 3 Vergleichende Zoologie, Institut für Biologie, Humboldt-Universität zu Berlin, Philippstraße 13, Haus 2, 10115 Berlin, Germany; [email protected] * Correspondence: [email protected]; Tel.: +31-7-1751-9600 Received: 14 October 2020; Accepted: 10 November 2020; Published: 16 November 2020 Abstract: Almost all pea crab species in the subfamily Pinnotherinae (Decapoda: Brachyura: Pinnotheridae) are considered obligatory endo- or ectosymbionts, living in a mutualistic or parasitic relationship with a wide variety of invertebrate hosts, including bivalves, gastropods, echinoids, holothurians, and ascidians. While the subfamily is regarded as one of the most morphologically adapted groups of symbiotic crabs, the functionality of these adaptations in relation to their lifestyles has not been reviewed before. Available information on the ecomorphological adaptations of various pinnotherine crab species and their functionality was compiled in order to clarify their ecological diversity. These include the size, shape, and ornamentations of the carapace, the frontal appendages and mouthparts, the cheliped morphology, the ambulatory legs, and the reproductive anatomy and larval characters. The phylogenetic relevance of the adaptations is also reviewed and suggestions for future studies are made. Based on an updated list of all known pinnotherine symbiont–host associations and the available phylogenetic reconstructions, it is concluded that, due to convergent evolution, unrelated species with a similar host interaction might display the same morphological adaptations.
    [Show full text]