ABSTRACT
Recent evidence shows that Acropora palmata within the Veracruz Reef System, located in the southwestern Gulf of Mexico, may be recovering after the die off from the flooding of the Jamapa River and a dramatic cold water event in the 1970s. Since this decline, few surveys have documented the status of A. palmata. The 28 named reefs in the system are divided into 13 northern and 15 southern groups by the River. Between 2007 and 2013, we surveyed 24 reefs to assess the benthic communities. Seven of the 11 reefs surveyed in the northern group and all in the southern group had A. palmata. Colonies were typically found on the windward side of the reefs in shallow waters along the reef edges or crest. We also recorded colony diameter and condition along belt transects at two reefs in the north (Anegada de Adentro and Verde) and two in the south (Periferico and Sargazo), between 2011 and 2013. In addition, eight permanent transects were surveyed at Rizo (south). A total of 1 804 colonies were assessed; densities ranged from 0.02 to 0.28 colonies/m² (mean (±SD), colony diameter of 58 ± 73cm, and 89 ± 18% live tissue per colony). Total prevalence of predation by damselfish was 5%, by snails 2%, and <1% by fireworms, disease prevalence was <3%. Size frequency distributions indicated that all of the sites had a moderate to high spawning potential, 15-68% of the colonies at each site were mature, measuring over 1 600cm². The presence of these healthy and potentially reproductive colonies is important for species recovery, particularly because much of the greater Caribbean still shows little to no signs of recovery. Conservation and management efforts of these reefs are vital.
Evidencia reciente indica que las poblaciones de Acropora palmata del sistema arrecifal de Vera Cruz, ubicado al suroeste del Golfo de México, podría estarse recuperando después de las inundaciones del río Jamapa e intrusiones de agua fría que afectaron la región en los años setenta. Desde la disminución, pocos estudios han documentado el estado A. palmata. Consiste de 28 arrecifes divididos 13 al norte y 15 al sur del río. Entre el 2007 y 2013 se muestrearon 24 arrecifes para caracterizar las comunidades bentónicas. Siete de los 11 arrecifes del norte y en todos los arrecifes del sur tenían A. palmata. Las colonias se encontraron por lo general en el barlovento de los corales en agua sómeras a lo largo del borde del arrecife. También registramos los diámetros de las colonias y condición a lo largo de transectos tipo conturón en dos arrecifes al norte (Anegada de Adentro y Verde) y dos en el sur (Periférico y Sargazo), entre el 2011 y 2013. Además, ocho transectos se evaluaron en Rizo (al sur). Evaluamos un total de 1 804 colonias; las densidades variaron entre 0.02 a 0.28 colonias/m² (promedio (±DE) del diámetro de colonia 58± 3cm y 89±18% de tejido vivo por colonia). La depredación fue 5% por peces damisela, 2% por caracoles y <1% por gusanos, prevalencia de enfermedades <3%. La distribución de tamaños indicó que las poblaciones tienen un potencial moderado a alto de desove, 15-68 de las colonias eran maduras, y medían más de 1 600cm².La presencia de estas colonias saludables y potencialmente reproductivas son importantes para la recuperación de especies, particularmente porque el Caribe muestra muy pocas o ninguna señale de recuperación. Esfuerzos en conservación y manejo en estos arrecifes es vital.
ABSTRACT
The endemic and threatened lizard Liolaemus lutzae has a relatively small geographic range restricted to only 200 km of along the coast of Rio de Janeiro State, Brazil, which are habitats under intensive anthropic disturbance. At the Barra da Tijuca beach, in Rio de Janeiro city an estimate of the population abundance made in 1991, compared to a previous estimate made in 1984, showed a considerable decrease (about 65 percent). Most of the decrease was attributed to anthropic disturbances that locally affected the beach vegetation, the species habitat. In this study we present estimates made in 2002 and in 2006 at the same area and compare them with the estimates of 1984 and 1991, using the same methodology in order to make comparable the data from different samplings years and to evaluate the present status of the local population. The estimated indexes of L. lutzae abundance in 2002 and in 2006 were higher than that of 1991. There was a significant increase in the mean number of recorded lizards in 2002 compared to 1991, but the mean number of lizards sighted in 2006 remained stable when compared with that of 2002. Our data based on the index of abundance recorded suggested that the number of L. lutzae at Barra da Tijuca beach recorded increased, which can be indicative of a potential recovery of the local population.
O lagarto endêmico e ameaçado de extinção Liolaemus lutzae possui distribuição geográfica relativamente reduzida a apenas 200 km ao longo da costa do Estado do Rio de Janeiro, Brasil, hábitats sobre intensa pressão de degradação. Na praia da Barra da Tijuca, cidade do Rio de Janeiro, uma estimativa do tamanho populacional feita em 1991 foi comparada a uma estimativa anterior feita em 1984, mostrou considerável decréscimo populacional (aproximadamente 65 por cento). Grande parte deste decréscimo foi atribuída a distúrbios antrópicos que afetaram localmente a vegetação de praia, o hábitat da espécie. Neste estudo, apresentamos estimativas feitas em 2002 e 2006 na mesma área e as comparamos com as estimativas de 1984 e 1991 Utilizamos a mesma metodologia, de modo a avaliar o presente status da população local. Os índices estimados da densidade populacional em 2002 e 2006 foram maiores que em 1991. Houve aumento significativo no número médio de lagartos amostrados em 2002 em comparação a 1991, porém o número médio de lagartos observados em 2006 permaneceu estável quando comparado às amostragens de 2002. Nossos dados sugerem que, após 2002, houve um aumento no número de L. lutzae registrados na praia da Barra da Tijuca com uma potencial recuperação da população local.