MSCI Dissertation Qualifying Exam - Mustafa GülThursday, May 25, 2017 - 2:00pm
Energetic consequences of anthropogenic impacts in Atlantic ghost crab, Ocypode quadrata
Sandy beaches have become the most preferred regions with recreational purposes in the world over the last century. Although those recreational activities provide an economic input, they cause disturbances on sandy beaches. Since every ecosystem has its unique properties, scientists use different species as bioindicator of those human disturbances. For sandy beach ecosystems, ghost crabs are the most common bioindicator species globally because of their sensitivity to anthropogenic and natural impacts. Besides, its importance as a bioindicator species, ghost crabs play a significant ecological role on sandy beach ecosystems by consuming the smaller invertebrates and by transferring the energy from smaller invertebrates to higher predators.
Ghost crabs typically show a dramatic decline in their density and size under high human disturbance. Previous studies showed that the abundance and the size of ghost crabs varied with the level and the types of disturbance. For example, the greatest impact was found in the sites where off-road vehicles were allowed at nights. Some previous studies discussed the possible reasons of those declines in the density and the size of the ghost crab populations. They found that, however vehicles had a detrimental impact on the ghost crab populations due to direct crushing, it could only be considered a partial reason for the decline in the density and the size. Also, vehicles cannot be considered as reason of decline in the sites where only the human impacts exist and off-road vehicles are not allowed.
In order to apply successful long term conservation and management plans to sandy beaches, it is important to understand how anthropogenic stress alter the population characteristics of ghost crabs as a bioindicator. To examine the mechanistic reasons for the decline in the density and the size of ghost crab populations on disturbed beaches, this proposal seeks to understand the possible reasons by combining laboratory and field studies. The proposal will basically focus on the energetic consequences of the human disturbance on ghost crab populations. The methods will include the examination of diet and habitat qualities, changes in growth and reproduction and other energetic demands such as burrowing activities on the sandy beaches under various types and levels of anthropogenic disturbance. Overall, the proposed methods will help to understand the effects of human disturbance on species in the impacted sites by examining their energetic demands and cost under various levels of disturbance.