Long-term monitoring

Sea Turtle In-water Monitoring Survey 2011

Seven sea turtles species inhabit the world’s oceans today and have a unique evolutionary lineage that dates back at least 110 million years.Sea turtle populations are declining worldwide due to different factors such as destruction and/or modification of habitats, nesting beaches being degraded by sand mining as well as commercial and tourist development, foraging grounds have been altered or destroyed, pollution, increased shipping traffic and recreational activities. Changes in the populations of juveniles and sub-adults are a early indicator for assessing the future of the sea turtle population as a whole. In-water surveys of sea turtle foraging grounds are a good tool to monitor population changes
A total of 35 in-water transects were made, two tour dives, one in day time and one at night and observations from the boat were made during the transect time by the captain. The in-water turtle survey was conducted between February and July 2011 within St.Eustatius National Marine Park boundaries.
A total of 16 sea turtles (11 greens sea turtles and five hawksbills) were observed during 25 hours and 20 minutes of dive time that includes transect dives, two tour dives and turtles observed from the boat during the transect time, yielding a Catch Per Unit E ffort of 0.63 within the marine park boundaries. During the 35 transect dives, seven sea turtles were recorded, four of them were green sea turtles and three were hawksbills. During the two tour dives seven sea turtles were recorded, six of them were green sea turtles and one was a hawksbill. The total number of observed turtles by the captain on the boat was two sea turtles, one green sea turtle and one hawksbill.

Date
2011
Data type
Research report
Theme
Research and monitoring
Geographic location
St. Eustatius
Author

Monitoring Tropicbirds, an introductory guide

This manual emphasises on practical methods, and some methods which (though highly accurate) are too labour-intensive or time-consuming for general monitoring use have been omitted. The methods presented in this manual deal only with assessment of population sizes, population changes, and the numbers of chicks produced by breeding pairs. It is also important to monitor other population parameters such as adult survival rates, diet, rate of food-delivery to chicks, or growth- rates of chicks. However, the methods required for monitoring survival rates, in particular, are labour-intensive for widespread use and are thus beyond the scope of this document. Some other measures and suggestions worth considering have been provided, but these largely go beyond monitoring and into the realm of research.

Please use this document as a guide, but remember there has been little published work on tropicbird species. Consequently, the opportunity to find new and important things about their biology, population ecology and conservation awaits you. 

Date
2010
Data type
Monitoring protocol
Theme
Education and outreach
Research and monitoring
Geographic location
Saba
St. Eustatius
Author

Coral reef crisis in deep and shallow reefs: 30 years of constancy and change in reefs of Curacao and Bonaire

Coral reefs are thought to be in worldwide decline but available data are practically limited to reefs shallower than 25 m. Zooxanthellate coral communities in deep reefs (30–40 m) are relatively unstudied. Our question is: what is happening in deep reefs in terms of coral cover and coral mortality? We compare changes in species composition, coral mortality, and coral cover at Caribbean (Curacao and Bonaire) deep (30–40 m) and shallow reefs (10–20 m) using long-term (1973–2002) data from permanent photo quadrats. About 20 zoo- xanthellate coral species are common in the deep-reef communities, dominated by Agaricia sp., with coral cover up to 60%. In contrast with shallow reefs, there is no decrease in coral cover or number of coral colonies in deep reefs over the last 30 years. In deep reefs, non- agaricid species are decreasing but agaricid domination will be interrupted by natural catastrophic mortality such as deep coral bleaching and storms. Temperature is a vastly fluctuating variable in the deep-reef environ- ment with extremely low temperatures possibly related to deep-reef bleaching. 

Date
2005
Data type
Scientific article
Theme
Research and monitoring
Journal
Geographic location
Bonaire
Curacao