Crecimiento

Considerando la importancia que tiene la tilapia negra (Oreochromis niloticus) como actividad económica para las comunidades cercanas a la represa La Esperanza, se planteó realizar un análisis del estado y estructura poblacional de esta especie para lo cual se realizaron monitoreos de abril a septiembre de 2014, determinándose en base a ello la composición de las capturas, estructura de tallas, relación longitud-peso, madurez sexual, así como también se estimaron los parámetros y curvas de crecimientos, tasas de mortalidad y coeficiente de explotación. Los resultados determinaron la talla media de captura en 29,6 para machos y en 28,0 cm LT en hembras así como también 30,8 cm de LT como talla media de madurez de hembras, además un LT∞=44,1 cm, K de 0,83/año, crecimiento isométrico, altas tasas de mortalidad y un coeficiente de explotación de 0,64, lo que permite considerar que O. niloticus en la zona de estudio se encuentra en estado de sobreexplotación como resultado del esfuerzo de pesca ejercido.

A mediados del siglo XX, Lima crece vertiginosamente debido a las migraciones de las zonas rurales hacia las periferias desocupadas de la ciudad. Las nuevas barriadas, autoconstruidas y autogestionadas, rápidamente se convierten en el paisaje de la pobreza, incorporando en su estructura urbana las formas de la arquitectura tradicional que se adaptan al contexto de la capital.
Por otro lado, la arquitectura moderna funcionalista actúa sobre la ciudad consolidada, destruyendo la arquitectura tradicional colonial sin respetar su escala o la trama urbana. Ambas ciudades se unen a partir de los años setenta convirtiendo a Lima en una superposición de capas históricas, urbanas y sociales y llamando la atención de sociólogos, arquitectos y antropólogos que estudian cómo el crecimiento no planificado de la ciudad está construyendo, espontáneamente, la identidad peruana.
El artículo presenta la visión crítica de uno de los arquitectos peruanos contemporáneos más importantes, Juvenal Baracco, quien propone una metodología de estudio de la ciudad en desarrollo y la traduce en un edificio en particular, la Escuela de la Fuerza Aérea del Perú, ubicada en la capital peruana. El estudio de Lima que realiza en el taller de la Universidad Ricardo Palma, así como sus propuestas arquitectónicas actúan sobre la idea de una ciudad en crecimiento de la que aún no se conoce la forma final.

In the middle of the 20th century, Lima grew rapidly due to migrations from rural areas to the unoccupied peripheries of the city. The new neighbourhoods, self-built and self-managed, quickly became the landscape of poverty, incorporating into their urban structure forms of traditional architecture that adapt to the context of the capital.
On the other hand, the modern functionalist architecture acts on the consolidated city, destroying the traditional colonial architecture without respecting its scale or urban layout. Both cities come together from the seventies, converting Lima into a superposition of historical, urban and social layers and, drawing the attention of sociologists, architects and anthropologists who study how the unplanned growth of the city is spontaneously building the Peruvian identity.
The article presents the critical point of view of one of the most important contemporary Peruvian architects, Juvenal Baracco, who proposes a methodology for the study of the developing city and translates it into a particular building, the School of the Air Force of Peru, located in the Peruvian capital. The study of Lima that makes in the workshop of the Ricardo Palma University, as well as his architectural proposals act on the idea of a growing city from which the final form is not yet know.

Effects of human disturbance on the population dynamics of Ocypode quadrata (Decapoda: Ocypodidae) in beaches of the Mexican Caribbean. The ghost crab Ocypode quadrata is a relevant species in the Western Atlantic beaches, and has been proposed as an indicator of human impact in these ecosystems. Eventhough some studies have covered various aspects of its natural history, no evaluations on the effects of human disturbance on its population dynamics have been made. This work compared the abundance, growth, and mortality of O. quadrata in two disturbed beaches (Aventuras and Majahual) and two preserved beaches (Xcacel and Puerto Angel) from the Mexican Caribbean. For this, nine samplings were made on each beach (every two to three months) between March 2013 and November 2014. Crabs were collected manually by three people, during the night first hours and for one hour, and a total area of 9 000 m 2 per beach. The crabs were measured, weighed, and separated into three groups: juvenile, male and female; while abundance was estimated by the number of collected crabs, and growth parameters were estimated using length frequencies. A total of 1 047 crabs were sampled in the four beaches; a higher crab abundance was found in the preserved beaches, but significant differences were only found between Puerto Angel and Majahual (Tukey, p<0.05). The adult-juvenile ratio was 1:1 in Xcacel and Aventuras, while in Majahual, more juveniles than adults were collected; and Puerto Angel had more adults than the juveniles. The size structure at Xcacel ranged from 4-32 mm, but in the rest of the beaches the minimum size was 5 mm. The maximum size at Aventuras, Majahual and Puerto Angel were 27 mm, 25 mm and 30 mm, respectively. The modal progression analysis of length's pooled data, revealed the presence of at least two groups of ages in all beaches. For all beaches, individuals smaller than 10 mm length were collected in almost all sampling months, indicating a continuous recruitment throughout the year. The length-weight relationship of the ghost crab was found isometric in the two preserved beaches, and negative allometric at the two impacted beaches. Crabs from Puerto Angel showed the highest body condition (Tukey, p<0.05). K-values ranged from 0.6-0.97/year and L∞ from 29.0 mm to 33.6 mm with higher values for the two preserved beaches. The highest mortality values were found in Xcacel and Aventuras. In the disturbed beaches, the destruction of the dunes, the mechanical cleaning and the removal of organic matter, seem to be the main causes that lead to a low abundance of crabs, their slower growth and higher mortalities. However, in the best preserved beaches, biological interactions appear to be the most important aspects in regulating the population dynamics of this species. These results supported the information that the ghost crab is a good indicator of human disturbance, and its population changes were clearly measurable and comparable among protected and impacted beaches; these results are also relevant for the management of sandy beaches in the Mexican Caribbean. Rev. Biol. Trop. 64 (4): 1625-1641. Epub 2016 December 01.