Resumo O Seybouse é um rio no nordeste da Argélia, é o segundo maior rio, tem uma área de captação de cerca de 6.500 km2 que acolhe cerca de 1,5 milhões de habitantes. Importantes atividades agrícolas e industriais são desenvolvidas nesta bacia hidrográfica. O uso de macroinvertebrados bentônicos como indicadores biológicos tem uma longa tradição em países desenvolvidos e está integrado em todas as avaliações da qualidade ecológica dos sistemas fluviais. O objetivo deste estudo foi revisar o inventário e o papel ecológico dos macroinvertebrados bentônicos nas águas interiores do rio Seybouse e determinar o impacto da poluição em suas distribuições. Resultados semelhantes foram relatados para outros países e rios argelinos. Este estudo enfoca a macrofauna bentônica de Wadi Seybouse e seus afluentes. Foram prospectados 03 locais, um no alto Seybousse Bouhamdane em Medjez Amar e dois no meio Seybousse Salah Salah Salah e Oued Zimba. Entre dezembro de 2019 e maio de 2020, dez parâmetros físico-químicos (pH, CE, DO, velocidade da água, NO3, Salinidade, NO2, MES, turbidez, deth) foram medidos para estabelecer um diagnóstico do estado de saúde desses ecossistemas aquáticos. A abordagem biológica complementar pela análise de populações de macroinvertebrados identificou 7.482 indivíduos e 40 táxons divididos em cinco classes: Crustáceos que são os mais dominantes, Insetos com as ordens principais (Ephemeroptera, Diptera, Trichoptera, Heteroptera e Odonata), Moluscos, Nematóides e Anelídeos. As análises físico-químicas e a aplicação dos índices de poluição orgânica, indicaram uma poluição forte a excessiva para todos os locais especialmente Salah Salah Salah.

Abstract The Seybouse is the second largest river basin in Algeria, hosting an important biodiversity and providing various ecosystem services. This watershed is highly influenced by agricultural and industrial activities, which threaten its biodiversity and ecosystem integrity. The use of benthic macroinvertebrates as biological indicators has a long tradition in developed countries and integrated into all assessments of the ecological quality of river systems. However, the macroinvertebrates of many North African regions are still not well studied, including those of the Seybouse river. The aim of this study is to assess the inventory and ecological role of benthic macroinvertebrates in inland waters of the Seybouse River and determine the impact of pollution on their spatial distributions. We sampled the benthic macrofauna of Wadi Seybouse and its affluents using regular surveys in three sites, of which one was in the upper Seybouse Bouhamdane in Medjez Amar and two in the middle Seybouse. Between December 2019 and May 2020, 10 physico-chemical parameters (pH, EC, OD, water speed, NO3, Salinity, NO2, MES, turbidity, depth) were measured in order to establish a health state diagnosis of these aquatic ecosystems. The complementary biological approach by the analysis of populations of macroinvertebrates identified 7482 individuals and 40 taxa divided into five classes: Crustaceans which were the most dominant, insects with the main orders (Ephemeroptera, Diptera, Trichoptera, Heteroptera and Odonata), Molluscs, Nematodes and Annelids. The physico-chemical analyzes and the application of the organic pollution indices indicated a strong to excessive pollution for all sites, especially in Seybouse upstream

Abstract. Pleuroncodes monodon is 1 of the 3 species sustaining the demersal crustacean fisheries in Chile, with landings that have had strong variations and a very slow recovery in the past decade. The southern fishing unit has been in the recovery status since 2017, following several years of intense overfishing, which affected the reproductive potential and the geographical distribution of the stock. In this study, fishing haul information from 14 direct evaluation surveys of P. monodon were used to estimate, by using geostatistics, the density of the reproductive potential of the female stock in central and southern Chile (32.0° S to 37.0° S) from 2005 to 2018. The annual mean potential eggs was estimated at 78,055.0 million potential eggs, with a mean density of 74.0 million eggs per square kilometer. Two areas of aggregation of the reproductive potential are recognized, one between 33.5° S and 34.5° S (northern zone) and the other between 35.5° S and 36.5° S (southern zone). The mean density of potential eggs was higher in the northern zone than in the southern zone, although in the southern zone there were foci with values close to 100 million eggs per square kilometer, which was not the case for the northern zone. The P. monodon population comes from a single breeding area located in the southern zone. In the 2008-2012 period, the female stock showed a net migration of 226.4 km northward (from 36°20ʹ52.5ʺ S to 34°18ʹ39.1ʺ S), although it was later reduced southward by the fishing pressure.

Resumen. Pleuroncodes monodon es 1 de las 3 especies que sustentan las pesquerías demersales de crustáceos en Chile, con niveles de desembarque que han mostrado amplias variaciones y una muy lenta recuperación en la última década. La unidad de pesquería sur se encuentra en estado de recuperación desde 2017, después de una intensa sobrepesca, la que afectó tanto al potencial reproductivo como a la distribución geográfica del stock. En el presente estudio, se usó información de lances de pesca de 14 campañas de evaluación directa de P. monodon para estimar la densidad del potencial reproductivo del stock de hembras en el periodo 2005-2018 en la zona centro-sur (32.0° S a 37.0° S) de Chile mediante un análisis geoestadístico. El promedio anual de huevos potenciales se estimó en 78,055.0 millones de huevos potenciales, con una densidad promedio de 74.0 millones de huevos por kilómetro cuadrado. Se reconocieron 2 zonas de agregación del potencial reproductivo, una entre 33.5° S y 34.5° S (zona norte) y otra entre 35.5° S y 36.5° S (zona sur). La densidad promedio de huevos potenciales fue mayor en la zona norte que en la zona sur, aunque en la zona sur se localizaron focos con máximos cercanos a 100 millones de huevos por kilómetro cuadrado, lo que no ocurrió en la zona norte. La población de P. monodon proviene de una sola área de cría, ubicada en la zona sur. En el periodo de 2008 a 2012, el stock de hembras presentó una migración neta con rumbo norte de casi 226.4 km (desde 36°20ʹ52.5ʺ S hasta 34°18ʹ39.1ʺ S), aunque posteriormente se redujo con rumbo norte-sur por la presión pesquera.

Abstract. Tagetes erecta L. (var. Marvel orange) a plant native to Mexico with traditional (used in religious ceremonies, as antiparasitic, insecticide, etc.) and industrial uses (flour of young flowers is used as food supplement in chicken and crustacean farms for its high content of carotenoids). Currently, there is great interest in achieving stable genetic transformation of this species with genes of agricultural interest; thus, the objective of this work was to optimize a protocol for stable transformation of T. erecta L. Shoot-tips from in vitro seedlings were transformed with Agrobacterium tumefaciens LBA4404 strain carrying the binary vector pCAMBIA 2301. Regeneration of transformed seedlings was performed in the presence of 50 mg·L-1 kanamycin. Stable genetic transformation of plantlets was demonstrated through positive GUS staining in leaves and flowers. PCR analysis detected the presence of a 600 bp fragment of the neomycin phosphotransferase II (NPTII) gene in the genomic DNA from regenerated seedlings. Transformation frequency was 40 %. To the best of our knowledge, this work is the second report of a successful stable transformation of T. erecta L. plants with GUS reporter via A. tumefaciens. This transformation protocol can be used to introduce genes in T. erecta L. to manipulate the isoprenoids biosynthetic pathways.

Resumen. Tagetes erecta L. (var. naranja Marvel) es una planta originaria de México con usos tradicionales (utilizada en ceremonias religiosas, como antiparasitario, insecticida, etc.) e industriales (la harina de flores jóvenes se usa como complemento alimenticio en granjas de pollos y crustáceos por su alto contenido en carotenoides). Actualmente, existe un gran interés en lograr la transformación genética estable de esta especie con genes de interés agrícola; por lo tanto, el objetivo de este trabajo fue optimizar un protocolo para la transformación estable de T. erecta L. Las puntas de brotes de plántulas in vitro se transformaron con la cepa LBA4404 de Agrobacterium tumefaciens que lleva el vector binario pCAMBIA 2301. La regeneración de las plántulas transformadas se realizó en presencia de 50 mg·L-1 de kanamicina. La transformación genética estable de las plántulas se demostró mediante tinción positiva de GUS en hojas y flores. Los análisis de PCR detectaron la presencia de un fragmento de 600 pb del gen de la neomicina fosfotransferasa II (NPTII) en el ADN genómico de las plántulas regeneradas. La frecuencia de transformación fue del 40 %. Hasta donde sabemos, este trabajo es el segundo reporte de una transformación estable exitosa de plantas de T. erecta L. con el gen reportero GUS a través de A. tumefaciens. Este protocolo de transformación se puede utilizar para introducir genes en T. erecta L., para manipular las rutas de biosíntesis de isoprenoides.

ABSTRACT Background. In 1985, as part of a global project within the “Secretaría de Marina” and continued in the “Facultad de Ciencias, Universidad Nacional Autónoma de México” and in “Estudio y Conservación de la Naturaleza, A. C.”, a collection series of stomatopods and decapods crustaceans that inhabit the coral reefs of the East coast of Mexico began. Objective. Provide an updated inventory and analysis of species richness on 12 reefs for the two orders of crustaceans. Method. Manual collection, dredges, free and autonomous diving. Review of national and international collections and bibliographic records. Results. The 12 coral reefs studied are geographically distributed in four groups: northern Veracruz (97 species), central Veracruz (194 species), Campeche (130 species), and Yucatán (196 species). Twelve species, six genera, and five families are recognized for the stomatopods, and 314 species, 155 genera, and 55 families for the decapods. The family with the highest richness was the Alpheidae, with 53 species (due to the plasticity of occupying various available habitats in the reefs and by establishing symbiosis with other taxa), followed by Palaemonidae shrimps (29 species) and the spider crabs of the Mithracidae family (18 species). The Portunidae family (swimming crabs) presented 16 species, followed by porcelain crabs (15 species) and xanthoidean crabs (13 species). Twenty families presented only one species. Some species are considered “species in transit” such as Latreutes fucorum, Latreutes parvulus, and Portunus sayi, which were found to be associated with Sargassum spp. Conclusions. There is no doubt that the inventory of species of the Mexican reefs of the East coast will increase considerably by making a greater sampling effort at different tide phases and times of the year and sampling in specific habitats for certain species.

RESUMEN Antecedentes. En 1985, dentro de un proyecto global de la Secretaría de Marina y continuado en la Facultad de Ciencias de la Universidad Nacional Autónoma de México y en Estudio y Conservación de la Naturaleza, A. C., se inició una serie de recolectas de los crustáceos estomatópodos y decápodos que habitan en los arrecifes de coral de la costa este de México. Objetivo. Proveer un inventario actualizado y análisis de la riqueza de especies en 12 arrecifes para los dos órdenes de crustáceos. Métodos. Recolectas manuales, dragas, buceo libre y autónomo. Revisión de colecciones nacionales e internacionales y registros bibliográficos. Resultados. Los 12 arrecifes de coral estudiados están geográficamente distribuidos en cuatro grupos: Veracruz norte (97 especies), Veracruz centro (194 especies), Campeche (130 especies) y Yucatán (196 especies). Se reconocieron 12 especies, seis géneros y cinco familias para los estomatópodos y 314 especies, 155 géneros y 55 familias para los decápodos. La familia con la mayor riqueza fue Alpheidae con 53 especies (debido a la plasticidad de ocupar diversos hábitats disponibles en los arrecifes y al establecer simbiosis con otros taxones), seguido por los camarones Palaemonidae (29 especies) y los cangrejos araña de la familia Mithracidae (18 especies). La familia Portunidae (jaibas) presentó 16 especies, seguido de los cangrejos porcelánidos (15 especies) y los cangrejos xanthoideos (13 especies). Veinte familias presentaron solo una especie. Algunas especies son consideradas “especies en tránsito” como Latreutes fucorum, Latreutes parvulus y Portunus sayi, las cuales se encontraron asociadas a Sargassum spp. Conclusiones. Indudablemente el inventario de especies de los arrecifes coralinos mexicanos de la costa este, aumentará al efectuar un mayor esfuerzo de muestreo en diferentes fases de marea y épocas del año; así como, muestreos en los hábitats específicos para determinadas especies.

ABSTRACT The inland waters in the Andes Mountains in the extreme north of Chile are in a zone with a marked arid climate in the called Atacama Desert (23° S, Antofagasta region, Chile) that has sporadic rains mainly in January or February (summer rains/Altiplano winter), many of these water bodies have high mineral contents due high mineral contents, and low species diversity (mainly crustacea and insecta). The present study aims to do a comparative analysis of inland water crustaceans in different kinds of water bodies in the surroundings of San Pedro de Atacama and Salar de Atacama in the north of Chile using co-occurrence null model analysis. The results revealed a scarce species richness and random species associations due to the lack of a structured pattern and many recurring species in the studied sites. Species reported, and species associations agree with literature descriptions. Nevertheless, more ecological studies would be necessary to understand the community patterns in these water bodies.

RESUMEN Los cuerpos de agua en la cordillera de los Andes del extremo norte de Chile están en una zona con un clima árido marcado en el denominado Desierto de Atacama (23° S, Región de Antofagasta, Chile), que tiene lluvias esporádicas en enero o febrero (lluvias estivales/invierno altiplánico), muchos de estos cuerpos de agua tienen alto contenido de minerales y baja riqueza de especies (principalmente crustáceos e insectos). El objetivo del presente estudio es realizar un análisis comparativo de los crustáceos de aguas continentales en diferentes tipos de cuerpos de agua en los alrededores de San Pedro de Atacama y del Salar de Atacama en el norte de Chile usando análisis de modelos nulos de co-ocurrencia de especies. Los resultados revelaron que hay baja riqueza de especies y que las asociaciones de estas son aleatorias, debido a la carencia de un patrón estructurado, por la presencia de muchas especies repetidas en los sitios estudiados. Las especies reportadas y las asociaciones de especies reportadas concuerdan con los antecedentes de la literatura. No obstante, serían necesario más estudios ecológicos para comprender los patrones comunitarios en estos cuerpos de agua.

Resumo Isla Arena está localizada na coordenada 20°70’N - 90°45’W, de Campeche, México. Nesses estuários, o oceano se mistura com a água doce e os ecossistemas se concentram onde proliferam petenos e flamingos rosa. Crustáceos e moluscos abundam no mar. Apesar de sua enorme riqueza marinha, não há estudos realizados sobre a presença de microrganismos halofílicos nessas águas. Neste trabalho, a diversidade e estrutura da comunidade microbiana foram investigadas através de uma abordagem metagenômica e corroboradas para o sequenciamento de genes 16S rRNA. Verificou-se que o filo Fimicutes predomina com mais de 50%, quase na mesma proporção da classe Bacilli e com quase 41% de abundância relativa da ordem Bacillales. Os resultados do sequenciamento mostraram que uma das amostras apresentou alto percentual de similaridade (99,75%) pelo programa Nucleotide BLAST com um microrganismo peculiar: Bacillus subtilis. Nossos resultados demonstram que B. subtilis pode ser uma fonte eficiente de proteases, lipases e celulases, provenientes de comunidades microbianas halofílicas localizadas em áreas pouco exploradas.

Abstract Isla Arena is located in the coordinate 20° 70´ N - 90° 45´ W, from Campeche, Mexico. In these estuaries, the ocean mixes with fresh water, and ecosystems are concentrated where petenes and pink flamingos proliferate. Crustaceans and mollusks abound in the sea. Despite its enormous marine wealth, there are no studies carried out on which halophilic microorganisms are present in these waters. In this work, the diversity and structure of the microbial community was investigated through a metagenomics approach and corroborated for sequencing of 16S rRNA genes. It was found that the phylum Fimicutes predominates with more than 50%, in almost the same proportion of the class Bacilli and with almost 41% of relative abundance of the order Bacillales. The sequencing results showed that one of the samples presented a high percentage of similarity (99.75%) using the Nucleotide BLAST program with a peculiar microorganism: Bacillus subtilis. This microorganism is one of the best characterized bacteria among the gram-positive ones. Our results demonstrate that B. subtilis can be an efficient source of proteases, lipases and cellulases, from halophilic microbial communities located in poorly explored areas.

Resumo A quitina e seus produtos derivados têm imenso valor econômico devido ao seu papel vital em várias atividades biológicas, bem como em aplicações biomédicas e industriais. Insetos, microrganismos e crustáceos são o principal suprimento de quitina, mas a casca dos crustáceos como camarão, krill, lagosta e caranguejo são as principais fontes comerciais. O conteúdo de quitina de um indivíduo varia dependendo das estruturas que possuem o polímero e da espécie. Neste estudo, as cascas de caranguejos comestíveis (Callinectes sapidus) foram desmineralizadas e desproteinizadas, resultando em 13,8% (peso seco) de recuperação de quitina a partir de resíduos de quitina. As análises de FTIR e XRD do bruto experimental, bem como das quitinas purificadas, revelaram que ambas eram muito comparáveis aos controles adquiridos comercialmente. O pré-tratamento com ácido cedeu 54 g de quitina coloidal que resultou em 1.080% da quitina bruta. A quitina coloidal foi analisada para isolamento de 85 isolados bacterianos quitinolíticos de diferentes fontes. A zona de eliminação foi exibida pelos 35 isolados (41,17%) que sucederam seu crescimento a pH 7 em meio de ágar de quitina coloidal. A atividade quitinolítica máxima, ou seja, 301,55 U / ml, foi exibida pelo isolado JF70 quando cultivado em quitina extraída contendo carbono e nitrogênio. O estudo mostrou que resíduos de caranguejos azuis podem ser utilizados para extração de quitina e isolamento de bactérias quitinolíticas que podem ser usadas para degradar resíduos de quitina, resolver a poluição ambiental e também para fins industriais.

Abstract Chitin and its derived products have immense economic value due to their vital role in various biological activities as well as biomedical and industrial application. Insects, microorganism and crustaceans are the main supply of chitin but the crustaceans shell like shrimp, krill, lobsters and crabs are the main commercial sources. Chitin content of an individual varies depending on the structures possessing the polymer and the species. In this study edible crabs’ shells (Callinectes sapidus) were demineralized and deproteinized resulting in 13.8% (dry weight) chitin recovery from chitin wastes. FTIR and XRD analyses of the experimental crude as well as purified chitins revealed that both were much comparable to the commercially purchased controls. The acid pretreatment ceded 54g of colloidal chitin that resulted in 1080% of the crude chitin. The colloidal chitin was exploited for isolation of eighty five chitinolytic bacterial isolates from different sources. Zone of clearance was displayed by the thirty five isolates (41.17%) succeeding their growth at pH 7 on colloidal chitin agar medium. Maximum chitinolytic activity i.e. 301.55 U/ml was exhibited by isolate JF70 when cultivated in extracted chitin containing both carbon and nitrogen. The study showed wastes of blue crabs can be utilized for extraction of chitin and isolation of chitinolytic bacteria that can be used to degrade chitin waste, resolve environmental pollution as well as industrial purpose.

Abstract The Helminthological Collection of the Oswaldo Cruz Institute is the biggest in Latin America and it is among the largest collections at worldwide reference level, with around 40,000 sets of specimens and approximately one million individual specimens. It contains helminths parasites of vertebrate and invertebrate animals that form part of the fauna of Brazil and other countries. The samples comprise holotypes, paratypes and representative specimens of Platyhelminthes, Acanthocephala, Nematoda and other non-helminth phyla, such as Annelida and Arthropoda. Some of the samples preserved in liquid media were found to have dried out. This made it impossible to analyze these samples morphologically for taxonomic purposes. The aim of this study was to test techniques used for rehydration of the tegument of specimens that had been found to have dried out and present protocols for such techniques. A total of 528 specimens that either no longer were immersed in preservatives or had already dried out were analyzed: 96 digenetic trematodes, 45 cestodes, 22 acanthocephalans, 357 nematodes, four hirudineans and four pentastomid crustaceans. The technique of rehydration using only distilled water on the specimens proved to be efficient for recovering tegument malleability, for all samples analyzed in this present study.

Resumo A Coleção Helmintológica do Instituto Oswaldo Cruz é a maior da América Latina e está entre as maiores coleções de referência mundial, com cerca de 40.000 lotes e, aproximadamente, um milhão de espécimes. Seu acervo reúne helmintos parasitos de animais vertebrados e invertebrados da fauna brasileira e de outros países. Seus exemplares são holótipos, parátipos e espécimes representativos de parasitos, pertencentes aos filos Platyhelminthes, Acanthocephala, Nematoda e, ainda alguns espécimes não-helmintos, pertencentes aos filos Annelida e Arthropoda. Parte das amostras preservadas como material líquido foram encontradas dessecadas. Esta condição torna as amostras inviáveis para análise morfológica para propósitos taxonômicos. Portanto, o objetivo deste trabalho foi testar técnicas usadas na reidratação do tegumento dos espécimes que se encontram dessecados e apresentar seus protocolos. Foram analisados 528 lotes, cujos espécimes encontravam-se sem conservantes ou já dessecados: 96 trematodeos digenéticos, 45 cestoides, 22 acantocéfalos, 357 nematoides, quatro hirudíneos e quatro crustáceos pentastomídeos. A técnica de reidratação dos espécimes, utilizando-se apenas água destilada, mostrou-se eficiente na recuperação da maleabilidade tegumentar de todas as amostras trabalhadas no presente estudo.

Abstract A study of the parasite-host interactions was conducted in the protected area popularly known as the “Refúgio Biológico de Santa Helena” and its tributary, the São Francisco Falso River. For each of the three host species, Schizodon borellii, Hoplias aff. malabaricus, and Trachelyopterus galeatus, 30 fish were collected from 2018 to 2019. A total of 2172 parasites were identified among the three host species. Among these, the Monogenea class had the highest number of species, with 26 taxa, followed by Copepoda with eight taxa, Digenea with six taxa, and Cestoda and Nematoda with one taxon each. Eleven new records of infection/infestation were found among the host species such as Urocleidoides paradoxus, Urocleidoides ramentacuminatus, Rhinoxenus arietinus, Mymarothecioides sp. (Monogenea), Ergasilus cf. bryconis, Lernaea devastatrix, and Brasergasilus sp. (Copepoda) parasitizing S. borellii. Trinigyrus sp., Vancleaveus sp. (Monogenea), Gamispinus diabolicus (Copepoda) present in T. galeatus, and Gamidactylus jaraquensis (Copepoda) present in H. aff. malabaricus. This study contributes to the record of parasite species occurrence in the vicinity of a protected area and helps fill gaps in the knowledge of fish parasitic fauna in the Neotropical region.

Resumo Foi realizado um estudo das interações parasitas-hospedeiros na área de proteção popularmente conhecida como “Refúgio Biológico de Santa Helena” e seu afluente, o Rio São Francisco Falso. Para cada uma das três espécies hospedeiras, Schizodon borellii, Hoplias aff. malabaricus e Trachelyopterus galeatus, foram coletados 30 peixes entre 2018 e 2019. Foi identificado um total de 2.172 parasitos entre as três espécies hospedeiras. Dentre estes, a classe Monogenea apresentou o maior número de espécies, com 26 táxons, seguida por Copepoda com oito táxons, Digenea com seis táxons, e Cestoda e Nematoda com um táxon cada. Foram encontrados onze novos registros de infecção/infestação entre as espécies hospedeiras tais como Urocleidoides paradoxus, Urocleidoides ramentacuminatus, Rhinoxenus arietinus, Mymarothecioides sp. (Monogenea), Ergasilus cf. bryconis, Lernaea devastatrix e Brasergasilus sp. (Copepoda) parasitando S. borellii. Trinigyrus sp., Vancleaveus sp. (Monogenea), Gamispinus diabolicus (Copepoda) presentes em T. galeatus, e Gamidactylus jaraquensis (Copepoda) em H. aff. malabaricus. Este estudo contribui para o registro da ocorrência de espécies de parasitos nas proximidades de uma área protegida, e ajuda a preencher lacunas no conhecimento da fauna parasitária de peixes na região Neotropical.

Keywords The productive performance of Clarias gariepinus, fed with by-products from the pulp extraction process of the lobster cephalothorax (Panulirus argus), was evaluated. An amount of 240 young fish of 10.16 ± 0.07 g initial mean weight were used, placed according to a completely randomized design in four treatments with three repetitions. The treatments were: control (100 % fish by-products), TI (75 % fish by-products and 25 % lobster by-products), TII (50 % fish by-products and 50 % lobster by-products) and TIII (100 % lobster by-products). Animals were fed for 45 days and feed was provided at 15 % of the biomass. The increase in lobster by-products in the rations decreased the amount of feed supplied per animal (137.15, 120.38, 109.72 and 86.53 g). Similarly, growth indicators (74.51, 52.91, 43.01 and 20.51 g) and feed conversion (2.41, 3.18, 3.78 and 9.81) were unfavorable when increasing the levels of these by-products, due to lower feed intake and, therefore, of proteins. Survival was 100 % for all treatments. The negative results were related to the high concentrations of chitin in natural form and calcium, present in these by-products. It is concluded that fresh lobster by-products were not feasible for feeding Clarias gariepinus. Its transformation into products with high added value, such as chitin, chitosans and protein concentrates, is recommended for subsequent evaluation as growth enhancers in this species.

Palabras Se evaluó el comportamiento productivo de Clarias gariepinus, alimentados con subproductos del proceso de extracción de pulpa del cefalotórax de langosta (Panulirus argus). Se utilizaron 240 alevines de 10.16 ± 0.07 g de peso medio inicial, ubicados según diseño completamente aleatorizado en cuatro tratamientos con tres repeticiones. Los tratamientos fueron: control (100 % de subproductos de pescado), TI (75 % de SP y 25 % de subproductos de langosta), TII (50 % subproductos de pescado y 50 % subproductos de langosta) y TIII (100 % de subproductos de langosta). Los animales se alimentaron durante 45 días y se suministró el alimento al 15 % de la biomasa. El incremento de los subproductos de langosta en las raciones disminuyó la cantidad de alimento suministrado por animal (137.15, 120.38, 109.72 y 86.53 g). De igual forma, los indicadores de crecimiento (74.51, 52.91, 43.01 y 20.51 g) y la conversión alimentaria (2.41, 3.18, 3.78 y 9.81) se desfavorecieron al incrementar los niveles de estos subproductos, por los menores consumos de alimento y por tanto, de proteínas. La supervivencia fue de 100 % para todos los tratamientos. Los resultados negativos se relacionaron con las altas concentraciones de quitina en forma natural y calcio, presentes en estos subproductos. Se concluye que los subproductos de langosta frescos no fueron factibles para la alimentación de Clarias gariepinus. Se recomienda su transformación en productos de alto valor añadido, como quitina, quitosanos y concentrados proteicos, para su posterior evaluación como potenciadores de crecimiento en esta especie.

Resumen Introducción: Los equinoideos (erizos de mar) brindan refugio a una variedad de ectosimbiontes facultativos u obligatorios. Objetivo: Evaluar la hipótesis de que los decápodos y los peces prefieren asociarse con individuos y especies de equinoideos con espinas más largas. Métodos: Estudiamos visualmente la frecuencia de crustáceos decápodos y peces asociados con equinoideos en aguas poco profundas (< 4 m) y aguas más profundas (5-20 m) en Los Cabos, Baja California Sur, México, del 1-6 de enero 2019. Resultados: Examinamos 1 058 equinoideos de seis especies. Cinco especies de decápodos se asociaron con tres especies de equinoideos. Al comparar con otras especies de equinoideos, en aguas poco profundas, los decápodos se asociaron 5.1 veces más frecuentemente con la especie de equinoideo de espinas más largas, Diadema mexicanum (7.0 veces más decápodos por individuo en D. mexicanum); en aguas más profundas, la frecuencia fue similar para todas las especies de equinoideos. Catorce especies de peces se asociaron con 4 especies de equinoideos. En aguas poco profundas, los peces se asociaron 2.6 veces más con D. mexicanum (4.5 veces más peces por individuo). No hubo preferencia por una especie de equinoideo en aguas más profundas. Individuos de D. mexicanum con espinas largas tuvieron más asociación con decápodos y peces. Las asociaciones se dieron con mayor frecuencia en aguas poco profundas. Múltiples individuos y especies de decápodos y peces a menudo se asociaron con un solo D. mexicanum. Un decápodo que presumiblemente es Tuleariocaris holthuisi mostró una posible asociación obligatoria con uno de los equinoideos (D. mexicanum); las otras especies de decápodos y todas las especies de peces presentaron asociaciones facultativas. Conclusión: Nuestros resultados apoyan la hipótesis de que los decápodos y los peces se asociaron con mayor frecuencia con los equinoideos con las espinas más largas, presumiblemente para reducir el riesgo de depredación.

Abstract Introduction: Echinoids (sea urchins) provide shelter for a variety of facultative or obligatory ectosymbionts. Objective: To evaluate the hypothesis that decapods and fishes prefer to associate with echinoid individuals and species that have longer spines. Methods: We visually studied the frequency of decapod crustaceans and fishes associated with echinoids in shallow water (< 4 m) and deeper water (5-20 m) at Los Cabos, Baja California Sur, Mexico, during 1-6 January 2019. Results: We inspected 1 058 echinoids of six species. Five decapod species associated with three species of echinoids. When compared with other echinoid species, in shallow water, decapods associated 5.1 times more often with the longest-spined echinoid Diadema mexicanum (7.0 times more decapods per individual D. mexicanum); in deeper water, association frequency was similar for all echinoid species. Fourteen fish species associated with four echinoid species. In shallow water, fishes associated 2.6 times more with D. mexicanum (4.5 times more fishes per individual). There was no preferred echinoid species in deeper water. Longer-spined D. mexicanum had more decapods and fishes. Associations were more frequent in shallow water. Multiple individuals and species of decapods and fish often associated together with a single D. mexicanum. The decapod that presumably is Tuleariocaris holthuisi showed a possible obligatory association with one of the equinoids (D. mexicanum); the other decapods and all fish species are facultative associates. Conclusion: Our results support the hypothesis that decapods and fishes associate most frequently with echinoids with the longest spines, presumably to reduce the risk of predation.

RESUMEN La quimotripsina en crustáceos es una enzima cuya importancia no ha sido del todo reconocida a lo largo del tiempo, a pesar de ser un componente fundamental en la digestión de las proteínas de sus alimentos. Las enzimas son componentes catalíticos básicos del metabolismo celular, de gran diversidad clasificadas acorde a la función que ejercen (hidrolisis, oxido-reducción, síntesis, isomerización, entre otros). La quimotripsina pertenece a las hidrolasas, que cataliza la ruptura de enlaces peptídicos adyacentes a los grupos carboxilo de los aminoácidos aromáticos triptófano, tirosina y fenilalanina. Desde la década de 1980 se han realizado pocos estudios relacionados con esta enzima en crustáceos, concentrando un tercio de estos (13 estudios) en los últimos cinco años. Por lo anterior, el presente artículo tiene como objetivo el presentar una revisión acerca de la información existente de estas enzimas en crustáceos desde una perspectiva general, contribuyendo a identificar las áreas de oportunidad para ampliar el conocimiento de su función y propiedades en estos invertebrados, así como las implicaciones ecológicas, etológicas, de manejo, alimentación y nutrición acuícola.

ABSTRACT Chymotrypsin in crustaceans is an enzyme whose importance has not been fully recognized over time, despite being a fundamental component in the digestion of proteins in their food. Enzymes are basic catalytic components of cellular metabolism; of great diversity classified according to the function they exert (hydrolysis, oxidation-reduction, synthesis, isomerization, among others). Chymotrypsin belongs to hydrolyses, which catalyzes the breaking of peptide bonds adjacent to the carboxyl groups of the aromatic amino acids tryptophan, tyrosine and phenylalanine. Since the 1980s there have been few studies related to this enzyme in crustaceans, concentrating a third of these (13 studies) in the last five years. Therefore, the paper aims to present a review about the existing information on these enzymes in crustaceans from a general perspective, helping to identify areas of opportunity to expand the knowledge of their function and properties in these invertebrates, as well such as the ecological, ethological, management, feeding and nutrition implications of aquaculture.

Resumen. Como base de supervivencia y desarrollo, el alimento de los peces representa una línea base para investigaciones sobre aspectos ecológicos relacionados con la estructura y la función de comunidades marinas. El presente estudio se orientó hacia los hábitos alimentarios del huachinango del Pacífico, Lutjanus peru, en Santa Rosalía, Baja California sur (México), durante agosto de 2016 hasta octubre de 2017. Un total de 403 especímenes fueron analizados y categorizados de acuerdo con el sexo, la madurez sexual y la estación climática. El intervalo de tallas fue de 21 a 60 cm de longitud total, y el peso varió de 195 a 1,920 g. En total, se identificaron 29 especies presa, incluidos peces (13 ítems), crustáceos (11 ítems), moluscos (4 ítems) y tunicados (1 ítem). De acuerdo con el índice porcentual de importancia relativa, las principales presas fueron Sardinops sagax (47.65%), Nycthiphanes simplex (38.50%), Harengula thrissina (11.21%), Myctophidae (0.68%) y Benthosema panamense (0.52%). Las presas fueron consumidas en diferentes proporciones de acuerdo con el sexo (F = 2.01, P < 0.049), la madurez sexual (F = 4.99, P < 0.001) y la estación climática (F = 45.52, P < 0.001). La amplitud trófica fue estrecha (B i = 0.16); esta fue consistente con la gráfica de Costello, la cual mostró un consumo principal sobre presas gregarias de origen pelágico-costero y mesopelágico. El huachinango del Pacífico en Santa Rosalía fue un consumidor terciario. Su alimentación oportunista incluyó pocos, pero abundantes ítems presa, y la composición trófica fue distinta a la de L. peru en otras áreas del golfo de California y la costa mexicana del Pacífico.

Abstract. A biological basis for survival and development, the diet of fish represents a baseline for research on ecological aspects related to the structure and function of marine communities. This study focused on the feeding habits of the Pacific red snapper, Lutjanus peru, in Santa Rosalía, Baja California Sur (Mexico), during August 2016 through October 2017. A total of 403 specimens were analyzed and categorized by sex, sexual maturity, and season. The size interval ranged from 21 to 60 cm total length, and the weight ranged from 195 to 1,920 g. A total of 29 prey items were identified, including fish (13 items), crustaceans (11 items), mollusks (4 items), and tunicates (1 item). According to the index of relative importance, the main prey were Sardinops sagax (47.65%), Nycthiphanes simplex (38.50%), Harengula thrissina (11.21%), Myctophidae (0.68%), and Benthosema panamense (0.52%). Prey were consumed in different proportions according to sex (F = 2.01, P < 0.049), sexual maturity (F = 4.99, P < 0.001), and season (F = 45.52, P < 0.001). The trophic width was narrow (B i = 0.16); this was consistent with the Costello graph, which showed the consumption of mainly pelagic-coastal and mesopelagic gregarious prey. The Pacific red snapper in Santa Rosalía functioned as a tertiary consumer. Its opportunistic diet included few highly abundant prey items, and the diet composition differed from that of L. peru in other areas of the Gulf of California and the Pacific coast of Mexico.

Resumen. El tiburón sedoso Carcharhinus falciformis es una de las especies de tiburón más importantes en las capturas de la pesquería de pequeña escala de la costa mexicana del Pacífico. En el presente trabajo reportamos los principales componentes alimentarios de C. falciformis capturados por la flota pesquera de pequeña escala en Acapulco, Guerrero, México, de acuerdo con la talla (neonatos y juveniles) y el sexo (machos y hembras), así como la amplitud de su nicho y nivel trófico. Se recolectaron en total 165 estómagos de C. falciformis, de los cuales 57 presentaron contenido estomacal y 108 se encontraron vacíos. Se identificaron en total 11 componentes alimentarios: 4 crustáceos, 3 peces, 2 cefalópodos, 1 tortuga marina y 1 ave. De acuerdo con el índice de importancia relativa especifica de la presa (%IIREP), el grupo de los crustáceos representó el 77.17% de la dieta. El cangrejo Portunus xantusii fue el componente más importante de la dieta de neonatos, juveniles, machos y hembras. Las dietas entre neonatos y juveniles y entre machos y hembras no presentaron grandes diferencias (índice de Morisita-Horn: 0.86 y 0.80, respectivamente). El tiburón sedoso presentó una amplitud de nicho estrecha en todas las categorías, lo que indicó una estrategia de alimentación de tipo especialista (índice de Levin <0.60). De acuerdo con el modelo de Amundsen, C. falciformis mostró una preferencia por P. xantusii. El nivel trófico determinado para C. falciformis indicó que es un depredador secundario.

Abstract. The silky shark, Carcharhinus falciformis, is one of the most important shark species in the small-scale fishery landings on the Pacific coast of Mexico. In the present work, we report the main food components of C. falciformis caught by small-scale fisheries in Acapulco, Guerrero, Mexico, according to size (neonates and juveniles) and sex (males and females), as well as reporting the niche breadth and trophic level. A total of 165 stomachs of C. falciformis were collected, of which 57 contained food and 108 were empty. A total of 11 prey groups were identified: 4 crustaceans, 3 fish, 2 cephalopods, 1 sea turtle, and 1 bird. According to the prey-specific index of relative importance (%PSIRI), crustaceans accounted for 77.17% of the diet. The crab Portunus xantusii was the most important component of the diet of neonates, juveniles, males, and females. The diets did not show great differences between neonates and juveniles and between males and females (Morisita-Horn index: 0.86 and 0.80, respectively). The silky shark presented a narrow niche breadth in all categories, indicating a specialist-type feeding strategy (Levin’s index <0.60). According to Amundsen’s model, C. falciformis showed preference for P. xantusii. The trophic level determined for C. falciformis indicated that it is a secondary predator.

RESUMEN Antecedentes En México, existen diversos trabajos sobre la nutria neotropical (Lontra longicaudis annectens), subespecie protegida (NOM-059-SEMARNAT-2010); sin embargo, son pocos los trabajos realizados en el estado de Campeche. Objetivos Conocer la abundancia y distribución de esta especie en laguna “La Lagartera” (río Palizada). Métodos Durante 2017 realizaron recorridos en la zona de estudio buscando evidencias indirectas de las nutrias en troncos de mangle analizando heces para conocer las presas. Resultados Se recorrieron 1.49 km en cada temporada climática (nortes, secas y lluvias), a bordo de una embarcación menor, obteniéndose un total de 99 rastros (85 heces, cinco comederos, cinco madrigueras y cuatro vocalizaciones). Se registró la distribución de estas evidencias dentro del área de muestreo y se estimó una abundancia relativa de 0.30 nutrias/km. El análisis de 85 heces colectadas sobre los troncos y/o raíces, registró seis grupos principales de presas: peces (40 %), crustáceos (26 %), reptiles (15 %), moluscos (11 %), mamíferos (4 %), aves (3 %) y otros no identificados (1 %). Conclusiones No se encontró evidencia que determine una variación en las frecuencias de consumo de los grupos presas por temporada. También se registró la presencia y consumo del pez diablo en todas las temporadas. Se confirma por medio de otolitos obtenidos en las heces, la presencia de cuatro especies nativas y cinco nuevos registros de peces presa. Con esta información se resalta el valor ecológico de la especie.

ABSTRACT Background Several works conducted in Mexico have addressed the Neotropical otter (Lontra longicaudis annectens), a protected subspecies (NOM-059-SEMARNAT-2010). Objectives To know the abundance and distribution of the neotropical otter in the State of Campeche in La Lagartera Lagoon (Palizada River). Methods During 2017 were searched the lagoon looking for indirect evidence on mangrove, collected and analyzed scats in order to identify preys. Results Were traveled 1.49 km in each climatic season (nortes, dry, and rainy seasons), on board a small vessel, recording a total of 99 signs (85 scats, five feeding sites, five dens, and four vocalizations). We recorded the distribution of these signs across the sampling area and estimated a relative abundance of 0.30 otters/km. The analysis of 85 scats collected on logs or roots recorded six major prey groups: fish (40 %), crustaceans (26 %), reptiles (15 %), mollusks (11 %), mammals (4 %), birds (3 %) and other unidentified prey (1%). Conclusions No evidence was found to suggest a variation in the consumption frequencies of the groups of prey by season. The presence and consumption of the “sailfin catfish” was also recorded in all seasons. The presence of four native species and five new records of prey fish was confirmed from otoliths contained in feces. This information highlights the ecological relevance of the species.