The San Diego Fairy Shrimp

By Timothy Rowe (nearly forgot to put my name)
Description and Ecology

The scientific name of the San Diego Fairy Shrimp as it is colloquially named is Branchinecta sandiegonensis. It is closely related to the vernal pool fairy shrimp which is Endemic to California and is considered a federally threatened species. It was first identified in 1962. San Diego Fairy Shrimp have large stalked compound eyes, no carapace, and 11 pairs of legs for swimming. Vernal pools are isolated sections of stagnant water in which many diverse plants and animals make their home. However, the isolation caused by the nature of vernal pools makes it difficult to maintain them especially in times of drought. The life cycle that they follow is intricately tied to the wet season. Eggs lie dormant during the dry season and during the wet season, they begin to hatch when water pools around them. They tend to hatch at similar times that germination for vernal pool plants occurs as well which coincides with their food source. They tend to hatch at lower temperatures which protects the species from the possibility of hatching too early during summer storms when not enough water will be available. Also, only a portion of roughly 10% of dormant eggs hatches at a time which protects against accidents due to dehydration. The San Diego Fairy Shrimp matures in only 2 weeks and then females lay anywhere between 100 and 300 eggs which then sink to the bottom of the pools where they also enter a dormant stage to await subsequent wet seasons.

(http://chaparralconservancy.org/wp-content/uploads/2010/09/malesandiego1.jpg)

(file:///C:/Users/Timothy/Downloads/Conservation%20plan.pdf)

Geographic and Population Changes

  They are most commonly found in small, shallow vernal pools, although they have been known to be found in ditches and road ruts with suitable conditions. None have been found in permanent pools of water such as rivers or oceans. They are primarily found in and around San Diego vernal pools but have been found as far south as northwestern Baja California, Mexico and as far north as Santa Barbara. The Santa Barbara finding was only one female in an isolated vernal pool. In Baja California, it has only been found in two locations. Larger deeper pools are more conducive to long term survival of shrimp populations since it protects against the change of pools drying out during warmer seasons.

(http://interwork.sdsu.edu/fire/resources/images/493_Vernal_Pool_II_crop.jpg)

(http://www.californiachaparral.com/images/627_3_16_03_Vernal_Pool_II.jpg)

Listing Date and Type of Listing

They were listed as endangered in 1997 and a plan for their conservation was made in 1998. They have a recovery priority of 2C which indicates that they have a high capacity for recovery but are currently under a large degree of threat. The "C" denotes that their potential for recovery conflicts with the possibility of development projects.

Cause of Listing and Main Threats to Continued Existence

The main threats facing the species were, and still are, habitat destruction caused by agricultural and urban development, draining of wetlands, offroading, cattle grazing, and other fairy shrimp species. which are habitat generalists in comparison. All of these factors have to do with the amount of water available to the shrimp populations. They are heavily reliant on stagnant wet lands to remain stable for long enough periods for eggs to hatch and mature in time to reproduce.

(http://chaparralconservancy.org/wp-content/uploads/2010/09/ProctorValleyPlannedVernalPool.jpg)

For instance, this location used to be a vernal pool, but after being heavily used as an offroad vehicle staging point, the water was dispersed and dried up.

Description of Recovery Plan

The objective of the recovery plan is aimed at conserving and enhancing the Southern California vernal pool ecosystem. Fairy shrimps are an important part of the ecosystem since they are fed on by waterfowl which in turn fertilize the vernal pools and germinate seeds. The overall aim is to reclassify several species from Endangered to threatened which includes the San Diego Fairy Shrimp. The criteria for progression of the recovery plan as laid out in 1998 are as follows:

1. existing vernal pools in a variety of ranges including the LA basin , Orange County, San Marcos, Ramona, etc... that are occupied by endangered species should be protected from further loss and degradation.

2. The existing vernal pools are to be secured in a way that maintains a functioning habitat and viability of species.

3. The secured vernal pools should be restored to population levels that existing species are stabilized or increased,

4. Finally, population levels must be shown to be stable for at least 10 years following reclassification.

Personal Action

The Chaparral Lands Conservancy is an organization currently dedicated to conserving the vernal pools and species of San Diego. Their actions include patrolling imperiled land, setting up fencing, cleaning up trash, and installing signs. Volunteering with their agency is a step you could take through their website http://chaparralconservancy.org or getting in contact with the San Diego council and express your support in the project.

References

http://ecos.fws.gov/docs/recovery_plan/980903a.pdf

http://chaparralconservancy.org/proctor-valley-vernal-pool-restoration/