A new pathology in the red abalone Haliotis rufescens (Mollusca: Gastropoda) cultured in Baja California, Mexico, associated with macro-crystal inclusions in gonadal tissue

Hidrobiológica 2015, 25 (2): 315-319 NOTAS Agosto 2015 A new pathology in the red abalone Haliotis rufescens (Mollusca: Gastropoda) cultured in Baja California, Mexico, associated with macro-crystal inclusions in gonadal tissue Una nueva patología en el abulón rojo Haliotis rufescens (Mollusca: Gastropoda) cultivado en Baja California, México, asociada con inclusiones de macro-cristales en tejido gonadal Jorge Cáceres-Martínez1,2, Rebeca Vásquez-Yeomans2 and Roberto Cruz-Flores1 Centro de Investigación Científica y de Educación Superior de Ensenada. Departamento de Acuicultura. Carretera Ensenada-Tijuana No. 3918, Zona Playitas, Ensenada, Baja California, 22860. México 2 Instituto de Sanidad Acuícola, A. C. (ISA). Calle 15 #265, entre Obregón y Moctezuma, Zona Centro, Ensenada, Baja California, 22800. México e-mail: 1 Cáceres-Martínez J., R. Vásquez-Yeomans y R. Cruz-Flores. 2015. A new pathology in the red abalone Haliotis rufescens (Mollusca: Gastropoda) cultured in Baja California, Mexico, associated with macro-crystal inclusions in gonadal tissue). Hidrobiológica 25 (2): 315-319. ABSTRACT A new severe pathological alteration in the gonadic tissue of red abalone was observed, which compromises reproduction of affected organisms. The alteration is related to the presence of numerous extracellular macro-crystal inclusions (Mci) reaching up to 300 µm in size. These Mci may be surrounded by hemocytes, cellular debris, and deposition of fibroblasts. Moreover, hypertrophy of the nuclei of cells in the top germinal epithelium and presence of brown cells in trabeculae were observed. The normal architecture of the tissue looks entirely altered and destroyed in some cases. No gonadal development was observed. The chemical nature of the Mci is unknown, but it is possibly related to inorganic toxic compounds. No previous records of similar alterations in abalone are known to exist. This record could help determine if this pathology has been observed in other abalone culture areas in the world, its possible origin, and if control is necessary. Key words: Extracellular crystal inclusions, Haliotis rufescens, pathology, red abalone. RESUMEN Se observó una nueva alteración patológica severa en el tejido gonadal de abulón rojo que compromete la reproducción de los organismos afectados. Esta alteración está asociada con la presencia de numerosas inclusiones extracelulares formadas por macro cristales (Mci) de hasta 300 µm de longitud. Estas Mci pueden estar rodeadas por hemocitos, restos celulares y acumulación de fibroblastos. Además, se observó hipertrofia del núcleo de las células del extremo externo del epitelio germinal y presencia de células cafés en las trabéculas. La arquitectura Vol. 25 No. 2 • 2015 normal del tejido se vió completamente alterada y en algunos casos destruida. No se observó desarrollo gonadal. La naturaleza química de las Mci no se conoce, pero posiblemente está relacionada con compuestos tóxicos inorgánicos. No se conocen registros previos de alteraciones similares en abulón. Este registro podría ayudar a determinar si esta patología se ha observado en otras áreas de cultivo a el abulón en el mundo, así como su posible origen y si es necesario su control. Palabras clave: Abulón rojo, Haliotis rufescens, inclusiones extracelulares de cristales, patología. Interest in the culture of red abalone Haliotis rufescens (Swainson, 1822) has increased in Baja California, Mexico, in part due to the decrease in the commercial fishery of blue abalone Haliotis fulgens (Philippi, 1845) and yellow abalone Haliotis corrugate (Wood, 1828), available culture technology, and market demands (Ramade-Villanueva et al., 1998; Searcy-Bernal et al., 2010). This species is also cultivated in California, USA (McBride, 1998) and has become a fast-growing industry in Chile where red abalone was introduced in 1977 (Flores-Aguilar, 2007). One of the main challenges for successful production is maintaining a healthy culture population. In this sense, sanitary surveillance must be permanent. Red abalone H. rufescens can be affected by different symbionts and parasites, such as ciliates in the esophageal pouch, ciliates in branchial filaments, the renal coccidian Margolisiella haliotis (Desser & Bower, 1997) that causes abalone coccidiosis, and the intracellular prokaryote Candidatus Xenohaliotis californiensis (Friedman, Andree, Robbins, Shields, Moore, Beauchamp, & Hedrick, 2000), a causal agent of withering syndrome (WS) in abalone that is flagged by the World Organisation for Animal Health (OIE). Descriptions of histopathological 316 alterations associated with these symbionts and parasites are relatively well described (Friedman et al., 1995; Gardner et al., 1995; Moore et al., 2000; Cáceres-Martínez & Tinoco-Orta, 2001; Alvarez-Tinajero et al., 2002; Cáceres-Martínez et al., 2011; OIE, 2014). However, the emergence of new infectious and non-infectious pathologies must be permanently recorded due to their potential negative impact in production. To date, reports on non-infectious diseases or descriptions of tissue alterations not associated to biologic agents in abalone are practically unknown. This note describes a new pathological condition associated with the presence of macro-crystal inclusions (Mci) of unknown composition located in the tissue between the inner and exterior walls of the gonad of cultured red abalone. In August 2004, six red abalone of a mean size of 72.5 mm in shell length, reared in an aquaculture facility located in Eréndira, Baja California, Mexico, were sent to the biology and pathology laboratory of aquatic organisms at the Centro de Investigación Científica y de Educación Superior de Ensenada, B.C. Mexico (CICESE) for health analysis. The abalone arrived live packed in ice. Two abalones had an externally healthy appearance; the others showed weakness, lethargy, mantle retraction, inability to adhere tightly to the substrate, and their foot muscle appeared shrunken. After an external analysis, the shell was detached from the soft body and tissues were individually fixed in Davidson´s fixative for 24 h. Four transverse sections containing portions of the digestive tract, gonad, kidney, muscle, and gills were processed for conventional histology. Deparaffinized 5 µm sections were stained with hematoxylin and eosin (Howard et al., 2004). Slides were reviewed under the microscope at magnifications of 100X to 630X looking for parasites and tissue alterations. Prevalence of parasites was estimated as the number of infected animals in the sample expressed in percentage (Olivas-Valdez & Cáceres-Martínez, 2002). The intensity of the infection was determined using specific scales previously established by Friedman et al. (1997) and Cáceres-Martínez and Tinoco-Orta (2001) for Candidatus X. californiensis and Friedman et al. (1995) for M. haliotis. A photographic record documented results. In February 2014 a sample of 30 fixed red abalone tissues was obtained (...truncated)