Spatial pattern of Plicopurpura patula pansa,in rocky shores of Guerrero, México
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Rocky shore
Pinus patula
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This study aimed to compare the density of Isognomon bicolor on four rocky shores of the State of Espírito Santo, Brazil. Further, size and weight comparisons were undertaken for the flat and creviced surfaces. Quarterly samplings were taken in 2006 and 2007, by removing organisms from 10 x 10 cm quadrants in the mid-intertidal zone, with five samples from flat surfaces and five from crevices. Although densities of I. bicolor were considered low as compared with those of other studies, this species is well established in the State. The most well-established population of I. bicolor was found in the rock crevices. The most important factor for the establishment of I. bicolor on rocky shores is substrate heterogeneity.
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<p>Las costas rocosas de origen calizo, son ecosistemas comúnes en el estado de Quintana Roo en México. En el verano del 2012, se realizó una investigación de campo de comunidades inter-mareales rocosas en 10 sitios del Estado, tanto en la Riviera Maya como en la Gran Costa Maya, con el objetivo de conocer si existe algún patrón en la abundancia y diversidad de los grupos que las componen. En cada sitio se realizaron tres transecciones perpendiculares a la costa con un número variable de muestras que dependió de la longitud de la playa, en cada nivel se obtuvo una muestra de 25 cm<sup>2</sup>, realizando un total de 593. Las pendientes de las playas fueron variables (0.4-1 m); sin embargo, como patrón recurrente, la parte sur de cada playa fue más extensa que la norte. La fauna estuvo representada por los siguientes grupos: equinodermos (15 especies-11 géneros), moluscos (84-50), anélidos (10-9), crustáceos (23-22), sipunculidos (1-1) peces (1-1), algas (53-34), estableciendo un total de 187 especies pertenecientes a 128 géneros. Los resultados muestran que los moluscos dominaron en todas las zonas intermareales. Otros grupos tuvieron preferencias hacia las zonas intermareales bajas. Los patrones geográficos regionales de la abundancia, riqueza de especies y biodiversidad, son poco claros para algunos grupos. El sitio con mayor riqueza y diversidad fue Osho Oasis en la Riviera Maya. El agrupamiento de los sitios a un nivel de similitud del 50 %, presentan uniones fuertes entre sitios de la Riviera Maya y de la Costa Maya indistintamente, con excepción de los equinodermos que identifican y separan a ese nivel de similitud ambas zonas. Utilizando un análisis monotético de contenido de información de orden 2, se obtuvieron las especies responsables de las mayores caídas de información de cada grupo, se tienen los siguientes resultados: Algas- <em>Padina santae-crucis</em>, Moluscos-<em>Tectarius antonii</em>, Crustáceos- <em>Maera inaequipes</em>, Equinodermos- <em>Tripneutes ventricosus</em> y Annelidos- <em>Pseudonereis variegata</em>, estas especies se consideran indicadoras de cambios en la estructura de las comunidades de cada grupo y podrían ser objeto de una investigación más profunda que sirva de apoyo y soporte a programas de manejo en esas áreas.</p>
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Riviera
Maya
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The state of Guerrero, Mexico, has approximately 470 km of seashore but the marine fauna is not well known. The coastline has three marine areas for priority conservation of coastal and oceanic biodiversity, for which Comisión Nacional para la Conservación y Uso de la Biodiversidad (CONABIO) notes a distinct lack of knowledge in these areas. This study was carried out in a rocky intertidal middle zone from Playa ‘Majahua’, Acapulco, located south of Bahia de Puerto Marques. The objectives were to study: the species richness for classes Gastropoda, Bivalvia and Polyplacophora; the community structure from the representation of classes, families and genera; estimate density and species composition within a community; analyse size and structure of populations in the mollusc community; and estimate the diversity index. Three samplings were made in the intertidal middle zone in 2009. Ten square metres were sampled at each visit. Ninety-nine mollusc species were found to be represented, corresponding to 36 families. From all of these species, no record in Acapulco was found for 21 Gastropoda, 5 Bivalvia and 8 Polyplacophora species recorded. Gastropoda was the best represented; 1737 organisms were analysed with an estimated density of 86.8 organisms/m2 and 31 species were dominant. Crucibullum umbrella was the largest sized species. The diversity and equity index estimate in Majahua was the highest found for the rocky coast of Guerrero, indicating a mega-diverse area with great uniformity.
Rocky shore
Polyplacophora
Global biodiversity
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This study presents a description of the tropical intertidal shores of Cocos Island (Isla del Coco), Pacific, Costa Rica. The intertidal zones were surveyed photographically with 116 digital images of quadrats (25 x 25 cm), and 130 of the cliffs in five days. The percent of cover and abundance of species in the intertidal zones were estimated by digital image analysis. Twenty-three taxa were found, Mollusca was the most specious (12 species). Littorinid and neritid mollusks were dominant in the higher littoral area. The predator snails Plicopurpura patula pansa, and Thais brevidentata, high densities of the pulmonate limpet Siphonaria gigas and some patches with low cover of the barnacle Tetraclita stalactifera were present in the mid-littoral zone. The encrusting algae dominate the rock surface at mid and low littoral and erect-frondose forms were only found in sheltered boulder shores. A high similarity in species identity was found between mainland and insular territories of the eastern tropical Pacific. Panamanian islands were most similar in terms of the algae assemblage of Cocos Island. The Galapagos Islands differ from Cocos Island in their higher erect-frondose and crustose algal cover, and lower densities of S. gigas. Grazing may be an important factor in structuring the intertidal community of Cocos Island and other regions of the eastern tropical Pacific. The main grazer in the cliffs and boulders was S. gigas which was larger in size (5.77 cm ± 1.00) than those of mainland and island sites in Costa Rica and Panama. Boulders and cliffs presented changes in the zonation and densities between sheltered or wave exposed areas. The position of organisms on the intertidal cliffs increased at high tidal level in more exposed sections of the coast. Moreover, topographic characteristics of boulders and cliffs influenced the densities of some gastropods around the island. Shores with ignimbrites, aa lavas or basaltic walls with a slight inclination towards the sea presented high densities of gastropods. The difference in the assemblages at Cocos Island from those of the continental and insular shores indicates high dynamics within intertidal tropical ecosystems. Rev. Biol. Trop. 56 (Suppl. 2): 171-187. Epub 2008 August 29.
Rocky shore
Intertidal ecology
Limpet
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