Curaçao’s water and sediment: Ostracods as past environmental indicators
While the main focus of the CCLP is to study human-environment interactions of the past by uncovering relics from that time, recent data can also provide valuable insights into past conditions. To achieve this, sediment samples containing micrometer-sized animals called ostracods have been collected from various locations across the island. By analyzing these ostracod communities and comparing them with those found in sediment cores, conclusions can be drawn about past environmental conditions.
Ostracods: Connecting the present and past
Ostracods are microscopic crustaceans that have existed for nearly 500 million years. Different species of ostracods inhabit water bodies with varying salinities, ranging from fresh rainwater ponds to the open ocean. These creatures are highly sensitive to environmental changes, particularly shifts in salinity. By collecting and analyzing present ostracod populations across different habitats on the island, a so-called “transfer function” can be established. This function indicates which species of ostracods live in specific salinity conditions. By examining the ostracods found in sediment cores taken during the field seasons and comparing the results with the transfer function, it is possible to infer past environmental conditions.
2024 field season: Laying the foundation for future work
In the 2024 field season, a total of 32 sediment samples were collected from across the island. The samples were treated with a special solution that only colors living organisms, allowing for the identification of specimens that were still alive at the time of sampling. Additionally, the samples were sieved, as the ostracods are found within the 0.1 to 1 millimeter fraction. The main goal was to obtain a broad range of salinities to develop an accurate transfer function. In addition to salinity, several other parameters were measured in the water bodies to assess water quality. These include pH, conductivity, oxygen levels, and alkalinity. Furthermore, 10 water samples were collected for laboratory analysis. These analyses will provide more information on the origin of the water, anthropogenic influences, and nutrient levels.
Testing Curaçao’s freshwater sources
Up until the 1970s a large part of Curaçao’s freshwater was sourced from wells. With the installation of desalination plants on the island, well water use has decreased substantially. Many of these wells still hold the opportunity to be used as freshwater sources for agricultural irrigation or industrial uses for example. As part of the cooperation with the Christoffel National Park, the wells located in the Christoffel Park territory as well as nine other wells found on old planation territories on the island were tested. While the water parameters only give a superficial overview of the water quality, all wells have relatively low salinity levels and otherwise good water quality. To determine if the wells produce potential drinking water further testing is necessary especially to determine potential pollution. Revitalizing wells as a source of drinking water could be a sustainable solution in the future, especially with the islands’ increasing demand of freshwater due to tourism, new construction and the rising costs of operating desalination plants.
Acknowledgements
A special thanks goes to Quinten Rico, manager of Christoffel National Park, and Roël O’Him, park ranger, for generously sharing their expertise on the island’s freshwater sites, granting access to the park, and facilitating meetings to explore some of the island’s historic plantations. We would also like to express our gratitude to the staff at Hofi E’Jardin, the Mongui Maduro Historic House Museum, Landhuis Bloemhof, and the Hato Caves for their kind cooperation in providing access to their properties.
Emily Sue Richter, November 25, 2024
Picture 1: Some common marine and brackwater ostracod species of Curaçao: 1 Cyprideis salebrosa 2 Perissocytheridea bicelliforma 3 Orionina bermudae 4 Ekpontocypris pirifera (pic by Emily Sue Richter)
Picture 2: Rebecca and Emily water sampling (pic by Yoshi Maezumi)
