The EGOMARS project investigated the relationship between hydrology and ecology by studying key animal species in the semi-tropical Yucatan Peninsula in Mexico. Queen conch marine snails (Strombus gigas) were studied to determine how this endangered and economically valuable species uses its habitat. Field studies were conducted at the Xel-Ha park, which means 'the place where the waters are born' in the local Mayan language. The park consists of a typical groundwater-fed coastal inlet habitat, known as a caleta, which provides a protected environment for large numbers of queen conch. Researchers tagged the marine snails with acoustic transmitters to record their movements. They discovered that over a 6-month period the queen conch has a small home range, comprising an area of around 40x50 metres. This showed that the queen conch does not need to go far to find food; however, over a one- or two-year period the story changes. Even though the marine snails are slow they are capable of moving large distances. As they grow older they move from more protected inshore waters towards the mouth of the inlet, while some travel to the deeper ocean. This has significant implications as the Xel-Ha is important for offshore populations of this threatened species. Therefore, EGOMARS demonstrated for the first time that groundwater-fed estuaries act as nurseries for queen conch. Project partners also investigated queen conch shells to unravel changes in environmental conditions during the life of the snail and to determine its age. The results indicated that the snail shell's distinctive pattern develops over 1.5 to 2 years before ceasing to increase in length and develop a thick shell lip. The shell pattern is similar to those of queen conch living in an ocean environment. This suggested that the stressful low-oxygen conditions of Xel-Ha that result from persistent groundwater flow do not significantly affect the snails' growth. EGOMARS will contribute to successful fisheries management by increasing understanding of coastal resources on Mexico's Yucatan coastline. This is especially true for iconic and endangered species such as the queen conch.
Queen conch, ecosystem, coastal zone, Yucatan Peninsula, Strombus gigas, Xel-Ha, groundwater, fisheries management