Abstract This study deals with population structure and habitat sharing of two sympatric aeglid species, Aegla jarai Bond-Buckup and Buckup, 1994 and Aegla muelleri Bond-Buckup and Buckup, 2010 at Espingarda Creek, Serra do Itajaí National Park, Rio Itajaí-Açú basin, Santa Catarina, Brazil. Individuals of A. jarai (n = 190) and A. muelleri (n = 131) were captured from June/2001 to May/2002 in monthly collection. A total of 89 males and 101 females (2 ovigerous) of A. jarai were collected with a sex ratio of 1:1, and 56 males and 75 females (2 ovigerous) of A. muelleri, with a predominance of females. Aegla jarai was larger than A. muelleri and the reproductive period of A. jarai was in the winter and spring, while that of A. muelleri was in the spring. Three cohorts were observed throughout the year, and both species have a recruiting period in the spring and summer. Both species perform their entire life cycle in the Espingarda Creek and their coexistence is attributed to space partitioning: the larger A. jarai lives in the large spaces formed between boulders, while the smaller A. muelleri shelters in the small spaces between pebbles.

Abstract We aimed to analyze the crustacean bycatch from the Xiphopenaeus kroyeri fishery in the Santa Catarina State and compare the bycatch’s biomass to that of the target species. Shrimp and environmental factors were sampled monthly from July 2010 through June 2011. For each crustacean species, we calculated the number of individuals, the relative abundance and the occurrence frequency. The relative abundance was classified as very abundant (Va), abundant (Ab) or low abundance (La), while the occurrence frequency was labeled continuous (Co), accessory (Ac) or accidental (Ad). We observed a total richness of 28 species, which is considered high for a subtropical region. Brachyura was the most frequent taxon (74%) followed by Penaeiodea (18%). Five species were considered Va (Arenaeus cribrarius, Callinectes danae, C. ornatus, Isochelis sawayai and Pleoticus muelleri), and eight species were considered Co (A. cribrarius, C. danae, C. ornatus, Farfantepenaeus paulensis, Hepatus pudibundus, Libinia spinosa, Litopenaeus schmitti and Sicyonia dorsalis), suggesting that the studied environment is heterogeneous and provides a variety of microhabitats, enabling many species to coexist. Therefore, the high species richness observed demonstrates the ecological importance of this region and thus the necessity of strategies aiming to minimize the impacts caused by trawling fisheries.

Abstract: This study analyzed the taxa associated as epibionts with mollusc shells inhabited by the hermit crab Isocheles sawayai, in order to understand how they affect host crabs. A total of 575 individuals were collected, including 156 females, 103 ovigerous females, and 316 males, which occupied shells of 10 species of gastropods. The epibionts recorded in the shells of I. sawayai belonged to Cirripedia, Polychaeta, Bivalvia, Anthozoa, Demosponge, and Bryozoa. A larger percentage of infestation occurred inside the shell, which may be harmful to the hermit crab because it reduces the internal volume. Ovigerous females used shells with a smaller percentage of infestation (40%), which may be related to the need for more space for the position and development of fertilized eggs. However, a higher proportion of anemones was found in shells used by ovigerous females. The advantage of this association for the anemones and crabs is discussed. The results suggest that shells occupied by epibionts can be a favorable factor for hermit crab survival, mainly for ovigerous females.

Resumen: Los taxones asociados como epibiontes con conchas de molusco usadas por el cangrejo ermitaño Isocheles sawayai fueron analizados para comprender como afectan al cangrejo hospedero. Se recolectó un total de 575 individuos, 156 hembras, 103 hembras ovígeras y 316 machos que ocuparon conchas de 10 especies de gasterópodos. Los epibiontes registrados en las conchas de I. sawayai pertenecieron a: Cirripedia, Polychaeta, Bivalvia, Antozoa, Demospongia y Bryozoa. Dentro de la concha, el porcentaje de infestación fue mayor, lo que puede ser perjudicial para el ermitaño, ya que reduce el volumen interno. Las hembras ovígeras utilizaron conchas con menor porcentaje de infestación (40%), lo que puede estar relacionado con la necesidad de más espacio disponible para la ovoposición y el desarrollo de los huevos fertilizados. Sin embargo, hubo una mayor proporción de anémonas en conchas ocupadas por hembras ovígeras. Se discute la ventaja de esta asociación para las anémonas y los cangrejos. Los resultados muestran que las conchas ocupadas por epibiontes pueden ser un factor favorable para la supervivencia del ermitaño, especialmente para hembras ovígeras.

Biodiversity and spatial-temporal distribution of hermit crabs captured as bycatch in the non-selective fishery of shrimp were analyzed in this study from July 2010 through June 2011 off coast Santa Catarina State (southern Brazil). Ecological indexes and redundancy analyses were conducted to understand the hermit community and their relationship with environmental factors. In total, 644 specimens were collected, representing two families, five genera, and six species, demonstrating remarkable species richness in the study area, mainly because Santa Catarina is a subtropical region. Isocheles sawayai showed the highest abundance, followed by Loxopagurus loxochelis. Both species demonstrated correlation with temperature (positive) and sediment grain size (negative). The highest richness and evenness values were estimated at the deeper area (17 m). However, in 5 m deep area showed the lowest evenness because of the high dominance of I. sawayai, resulting in a lower estimated diversity. During a period of lower temperature and higher salinity (July), higher levels of diversity were registered, probably because of the lower dominance of tropical species (I. sawayai) and the presence of some species distributed in offshore regions (Petrochirus diogenes, Dardanus insignis and Pagurus exilis). Thus, we detected that the capture effort designated in the shrimp fishery activities had a strong influence in the diversity of hermit crabs and other associated fauna, especially because of catch specimens in expressive abundance at various stages of development, including juveniles. This profile makes us argue in favor of constant monitoring of bycatch resources in order to preserve the marine fauna.

Se analizó la biodiversidad y distribución espacio-temporal de los cangrejos ermitaños, como descartes en la pesca no selectiva de camarón, entre julio de 2010 y junio de 2011 en la costa del Estado de Santa Catarina. Los índices ecológicos y análisis de redundancia se analizaron para describir el desarrollo de la comunidad de ermitaños y su relación con los factores ambientales. Se encontró una notable riqueza específica en una región subtropical, como fue la de Santa Catarina, donde se obtuvieron 644 individuos pertenecientes a dos familias, cinco géneros y seis especies. Isocheles sawayai presentó la mayor abundancia, seguida de Loxopagurus loxochelis; ambas especies mostraron correlación con la temperatura y tamaño de las partículas del sedimento. Los mayores valores de riqueza y uniformidad se dieron en la zona más profunda estudiada (17 m). Sin embargo, a 5 m de profundidad se encontró la equirepartición más baja debido al predominio de I. sawayai. Durante un período de baja temperatura y mayor salinidad (julio) se registraron altos valores de diversidad, probablemente debido la baja dominancia de especies costeras tropicales (I. sawayai) y presencia de algunas especies de aguas oceánicas (Petrochirus diogenes, Dardanos insignis y Pagurus exilis). Se detectó que el esfuerzo de captura aplicado en las pesca del camarón tuvo una fuerte influencia en la diversidad de los cangrejos ermitaños y fauna asociada, especialmente debido a que en las muestras se observaron diversas etapas de desarrollo de las especies, incluyendo juveniles. Estos resultados son argumentos a favor de una vigilancia constante de los descartes a fin de preservar la fauna marina.

Abstract The goal of this study was to identify patterns of shell occupation by different species of hermit crabs from the southern Brazilian coast. In total, 644 individuals were collected, represented by six hermit species. Isocheles sawayai Forest & Saint Laurent, 1968 showed the highest abundance, with 575 individuals, followed by Loxopagurus loxochelis (Moreira, 1901) (n = 56). The other species were Petrochirus diogenes (Linnaeus, 1758), Dardanus insignis (Saussure, 1858), Pagurus exilis (Benedict, 1892) and Pagurus leptonyx Forest & Saint Laurent, 1968. Loxopagurus loxochelis was found associated with shells of 12 gastropod species, with 75% of males occupying shells of Olivancilaria urceus (Roding, 1798) and 78% of females inhabiting shells of Semicassis granulata (Born, 1778). Shells of Semicassis granulata were the lightest of all gastropod shells, demonstrating differential resource utilization. Additionally, I. sawayai occupied shells of 10 species, highlighting Stramonita haemastoma (Linnaeus, 1767) with the highest occupation percentage in all demographic classes, confirming a pattern of occupation with a strong relationship to the availability of the resource. The comparison of our results with those of other studies corroborated the influence of region and gastropod diversity on gastropod shell occupation.