Evento de blanqueamiento masivo en la zona norte del Gofo Pérsico, 2012

Coral bleaching events due to elevated temperatures are increasing in both frequency and magnitude worldwide. Mass bleaching was recorded at five sites in the northern Persian Gulf during August and September 2012. Based on available seawater temperature data from field, satellite and previous studies, we suggest that the coral bleaching threshold temperature in the northern Persian Gulf is between 33.5 and 34°C, which is about 1.5 to 2.5°C lower than that in the southern part. To assess the bleaching effects, coral genera counted during 60-minute dives were categorized into four groups including healthy, slightly bleached ( 50% bleached tissue) and fully bleached colonies. The anomalously high sea surface temperature resulted in massive coral bleaching (~84% coral colonies affected). Acropora spp. colonies, which are known as the most vulnerable corals to thermal stress, were less affected by the bleaching than massive corals, such as Porites, which are among the most thermo-tolerant corals. Turbid waters, suggested as coral refugia against global warming, did not protect corals in this study since most affected corals were found in the most turbid waters. The 2012 bleaching in the northern Persian Gulf was relatively strong from the viewpoint of coral bleaching severity. Long-term monitoring is needed to understand the actual consequences of the bleaching event on the coral reefs and communities.Los eventos de blanqueamiento de corales están aumentando en frecuencia y magnitud debido al aumento de la temperatura en los océanos. En este trabajo se describe un evento de blanqueamiento masivo observado en seis localidades del norte del Golfo Pérsico entre Agosto y Septiembre de 2012. Los datos de temperatura disponibles, medidas in situ y observaciones de satélites de la temperatura de la superficie del mar, sugieren que la temperatura umbral que desencadena el blanqueo de coral en el norte del Golfo Pérsico corresponde a una temperatura de entre 33,5-34°C que es una temperatura entre 1.5 a 2.5°C inferior a la observada en las zonas más meridionales del Golfo Persico (35-36°C). Para la evaluación de los efectos de blanqueo sobre las comunidades de coral, se realizaron transectos de 60 minutos entre 0 y 6 m de profundidad. Durante las inmersiones cada colonia de coral se identificó a nivel de género y su estado se asignó a una de las siguientes categorías: no afectada, ligeramente afectada ( 50% del tejido blanqueado) y colonias totalmente afectadas (100% del tejido blanqueado). El análisis de los datos de temperatura permitió identificar una anomalía térmica durante el periodo de blanqueamiento que afectó a un 84% de las colonias censadas. Contrariamente a otros eventos de blanqueamiento analizados, las colonias de Acropora spp., que se encuentran entre las especies más vulnerables al estrés térmico, fueron menos afectadas que las especies de corales masivos como Porites spp. que normalmente presentan una gran resistencia al estrés térmico. Igualmente a pesar que la turbidez de las aguas ha sido señalada como un factor protector en el contexto del calentamiento global, en nuestro estudio observamos que las zonas más afectadas por el blanqueamiento presentaban las tasas de turbidez más elevadas. En conclusión el evento de blanqueamiento de 2012 observado en el norte del Golfo Pérsico afectó severamente a las comunidades de coral. El seguimiento a largo plazo de las comunidades de coral se presenta como una necesidad para comprender las consecuencias de los eventos de blanqueamiento

Coral reefs and community around Larak island (Persian Gulf)

Field surveys pertaining to coral reef studies were performed from November 2010 to August 2011 around Larak Island in the Persian Gulf. The Line Intercept Transect (LIT) method was applied to record biotic and abiotic components of the coral reefs at two sites around Larak Island: North East (NE) and South West (SW) with two stations per site. Mean "Live Coral Coverage" (LCC) and “Dead Coral Coverage” (DCC) at SW 21.74% ± 1.92%, 4.58% ± 0.65%and NE sites were 5.69% ± 0.54%, 35.64% ± 3.28% respectively. Dead Coral Coverage was more prevalent in the NE than in SW. Based on Mann-Whitney U-test LCC and DCC showed significant difference (p< 0.05) among these two sites, (p< 0.05); The Kruskal-Wallis test also showed significant difference (p< 0.05) among four stations within two sites. This study indicated that coral communities of the NE site have been more destroyed by human impacts such as municipal run-off, breakwater construction, trap fishing, over-fishing and several other human activities

A Study on Diet Composition and Feeding Habitats of Sillago sihama (Forsskål, 1775) in Coastal Waters of Bandar Abbas

The diet composition and feeding habits of Sillago sihama , were studied in the northern Persian Gulf restricted to coastal waters of Bandar Abbas within 14 months period, from July 2007 up to August 2008. Biometrical and anatomical measurements were carried out, and biological surveys were conducted on 572 specimens (238 Male and 306 Female). These samples were collected from coastal waters of Bandar Abbas by pool and line and Moshta. The measurements of the minimum and maximum total lengths and weights were 10.6 to 45.5 cm and 8.58 to 196.27 g, respectively. The calculated level of (R2) (correlations of total length & weight), indicated correlations between length and weight of this fish, and b was 2.75 that shows the growth is isometric. The results indicated that this species, having the Relative Length of Gut, RLG = 0.47± 0.15, is carnivorous. Examining the changes in the index of stomach emptiness by the percentage of CV = 59.88% indicates that this fish is Moderate feeder. Proven by the fact that benthos was taken as principle food, Crustacean, Shrimps, and fish as secondary food and other kinds of food as random. Among the food items, benthos, crustaceans, razor clam, crab, shrimp, fish, polychaetes, oligocheata, clams, shells, detritus, hermit crab, crayfish, were 59.15, 12.82, 6.22, 5.99, 5.91, 3.09, 2.55, 2.05, 0.83, 0.56, 0.46, 0.20 and 0.16 respectively. The level of feeding increased in February, before spawning and decreased in May, simultaneously with the spawning season

Coral reefs and community around larak island (Persian Gulf)

Field surveys pertaining to coral reef studies were performed from November 2010 to August 2011 around Larak Island in the Persian Gulf. The Line Intercept Transect (LIT) method was applied to record biotic and abiotic components of the coral reefs at two sites around Larak Island: North East (NE) and South West (SW) with two stations per site. Mean "Live Coral Coverage" (LCC) and “Dead Coral Coverage” (DCC) at SW 21.74% ± 1.92%, 4.58% ± 0.65%and NE sites were 5.69% ± 0.54%, 35.64% ± 3.28% respectively. Dead Coral Coverage was more prevalent in the NE than in SW. Based on Mann-Whitney U-test LCC and DCC showed significant difference (p< 0.05) among these two sites, (p< 0.05); The Kruskal-Wallis test also showed significant difference (p< 0.05) among four stations within two sites. This study indicated that coral communities of the NE site have been more destroyed by human impacts such as municipal run-off, breakwater construction, trap fishing, over-fishing and several other human activities

Mass coral bleaching in the northern Persian Gulf, 2012

Coral bleaching events due to elevated temperatures are increasing in both frequency and magnitude worldwide. Mass bleaching was recorded at five sites in the northern Persian Gulf during August and September 2012. Based on available seawater temperature data from field, satellite and previous studies, we suggest that the coral bleaching threshold temperature in the northern Persian Gulf is between 33.5 and 34°C, which is about 1.5 to 2.5°C lower than that in the southern part. To assess the bleaching effects, coral genera counted during 60-minute dives were categorized into four groups including healthy, slightly bleached (< 50% bleached tissue), mostly bleached ( > 50% bleached tissue) and fully bleached colonies. The anomalously high sea surface temperature resulted in massive coral bleaching (~84% coral colonies affected). <em>Acropora</em> spp. colonies, which are known as the most vulnerable corals to thermal stress, were less affected by the bleaching than massive corals, such as <em>Porites</em>, which are among the most thermo-tolerant corals. Turbid waters, suggested as coral refugia against global warming, did not protect corals in this study since most affected corals were found in the most turbid waters. The 2012 bleaching in the northern Persian Gulf was relatively strong from the viewpoint of coral bleaching severity. Long-term monitoring is needed to understand the actual consequences of the bleaching event on the coral reefs and communities