A picture of metal shelving filled with black plastic containers holding different covered species of the EAHCP from the refugia center.
EAHCP Refugia container habitats for EAHCP invertebrates.
The purpose of the Edwards Aquifer Habitat Conservation Plan (EAHCP) Refugia Program is to ensure survival of the 11 Covered Species during catastrophic events such as extreme drought or a chemical spill. In partnership with the U.S. Fish and Wildlife Service (USFWS), the EAHCP has two off-site refugia centers in San Marcos, the San Marcos Aquatic Resource Center (SMARC), and in Uvalde, the Uvalde National Fish Hatchery (UNFH).
USFWS staff collect the species, research their life history, and refine species’ propagation methodologies while they are in captivity. Results from this long-term program help enhance our knowledge and understanding of these unique species.
Shrimp-like creature with a translucent body
Peck's cave amphipod
Collection
A hand holding a fine net filled with gravel and sand, a small, orange Peck’s Cave amphipod is on the net being pushed up by a finger, no larger than a grain of rice.
PCA compared to the size of the gravel
EAHCP contractors and partners must have a research and
collection permit from USFWS when collecting Peck’s cave amphipod (PCA). This permit legally allows the researchers to disturb, collect, and research the protected species. To anyone else without a permit from USFWS, these actions would be considered illegal.
PCA are found in the Comal Springs system in New Braunfels, Texas. To collect PCA, USFWS staff go to springs and sift the sand and rocks, then transfer the PCA to jars that contain a net and transport them back to the refugia.
A picture of the Comal river floor, cobble and stones moved back showing fine gravel and sand underneath where small springs are bubbling up aquifer water.
Uncovered upwellings from beneath cobble and gravel; ideal PCA habitat
Collection of PCA starts with identification of upwellings in parts of Landa Lake where these amphipods are known to inhabit. They must search on the lake bottom for spots where bubbles are rising. Next, in those patches of bubbles, the collectors look for spaces with larger cobble over smaller gravel or sand, as the cobble is preferable to the PCA for hiding and prevents them from getting swept away by water current or recreational activities. Then in the carefully chosen bubbling spring area, the collectors gently move the larger cobble back so that the smaller gravel and sand is exposed underneath.
A snorkeler holds a dipnet full of gravel, searching for Peck's Cave Amphipods
Using a mesh net, the collectors scoop the gravel and sand and patiently search for the rust red-orange PCA’s amongst to tan, brown debris. Even with the knowledge of where to look and what to look for, it can be challenging to find this species, as their population numbers are low and they are rather tiny. The PCA is very small and delicate to handle, so they must be searched for and collected with the utmost care.
A plastic container with mesh, rocks and amphipods held by a researcher. A second researcher in a wetsuit is pictured in the background
Temporary holding container for collection and transportation to refugia
The collected amphipods are placed in temporary holding containers with “low density filter media and river water” and then transported to the refugia center (Britton, 2020).
Quarantine
Incoming Peck’s cave amphipods are quarantined for 30 days before joining the other Stygobromus pecki refugia population at the SMARC and UNFH. During quarantine USFWS staff monitor the amphipod species for potential aquatic nuisance species (ANS) that may have come in with the collected amphipods. Separation from the general stock population helps prevent large die-offs if there is a disease among the group. According to research done on the PCA in 2020, "the survival rates of PCA at UNFH were approximately 35% for the months of January-March 2019. After adding filter media as habitat, the overall survival rates increased: 58% in May, 80% in July, 88% in September, and 92% in November" (Britton, 2020). This shows that observation and beneficial modification of habitat and species wellbeing during the quarantine period is crucial to elongating research efforts of the PCA.
Housing
Pecks Cave Amphipod container at Refugia contains flow pipes, mesh net, and leaves
PCA habitat with pipe flow bars, mesh, and leaves
Peck’s cave amphipods are housed within custom-built aquatic holding units that simulate springflow and water movement. These dark environments are designed to mimic the natural underground environment where the species are found. Water is sourced from an Edwards Aquifer well at the facility. Their housing contains PVC pipe flow bars, a layer of mesh atop that to facilitate water flow, and a layer of about 10-15 grams of dry oak, sycamore and pecan tree leaves. Staff check daily for water temperature, adequate water flow, and clear drain screens to maintain drainage and water levels in the housing units.
PCAs are fed a combination of red fish flake paste and ostracods which are found on the submerged tree leaves.
Two plastic containers. One is full of red fish flake paste and the other is empty but with a small pipette
Different combinations of low-density (black) and medium-density (green) Matala® filters were added in between layers of leaves (Kosnicki, Ely & Eric Julius, 2019).
Different combinations of low-density (black) and medium-density (green) filters
Brooding Female Housing
During this same research project, the brooding female PCA’s were also placed into special separate housing for the birthing and raising of offspring. Below are examples of two brooding chambers from two separate studies. These experiments were conducted to aid in improving “survival rates of adult and captive bred PCA through an evaluation of habitat and eating requirements” (Britton, 2020). In the end, there was a 73% survival rate amongst the original 30 specimens collected for the 2020 research project.
A picture of female brooding housing with labels to illustrate the function of brooding females. It is two clear plastic containers side by side. The main chamber has a water input hole. There is an upper and lower part of the container that is divided by a piece of green plastic. There are leaves and filters in each chamber. There are several tubes running into the container.
This image depicts two, white tubes with netting blocking the ends. The inside is dark and undistinguishable.
This image depicts a rectangular container containing various density filters. The container is split in half horizontally to separate the mother and juvenile refuges. There are tubes connecting to the chambers for water input.
Examples of Brooding Chambers for Female PCA
Propagation
Propagation methods for this species are being developed as part of routine USFWS refugia operations and research projects. Currently, male and female wild stock are housed together in containers with leaves, mesh and filters. Females have recently been taken to separate brooding chambers for egg laying. Updated research estimates show that the species can take up to a year to fully develop from larvae to an adult, where they can live for up to a year in captivity as an adult. Researchers are learning more about their life cycle and habitat needs to help refine our understanding of rare and unique species.
Sources
Britton, David, et al. (2020). Increasing survival rate of Peck's cave amphipod: 2020 Research Report for the Edwards Aquifer Authority. U.S. Fish and Wildlife Service, From the Edwards Aquifer Refugia Program. 1-22.
Kosnicki, Ely & Eric Julius. (2019). Life History Aspects of Stygobromus pecki. BIO-WEST, Inc. Prepared for the Edwards Aquifer Authority. 1-74. Retrieved from: https://www.researchgate.net/publication/330345066_Life-History_Aspects_of_Stygobromus_pecki
