Barnacle growth rate on artificial substrate in the Salton Sea, California

Abstract

The Salton Sea is one of the few saline, inland lakes in the world with a population of barnacles, Balanus amphitrite. It is also one of California’s most impaired water bodies due to excessive nutrient loading which leads to phytoplankton blooms and low dissolved oxygen. Currently, B. amphitrite growth is limited due to lack of hard substrate in and around the Sea. We have hypothesized that artificial substrate could support the growth of B. amphitrite and their filter-feeding would lead to improved water quality. Periodic harvesting of the barnacles would result in the permanent removal of nitrogen and phosphorus from the Sea. A 44-day in-situ experiment was carried out in the Salton Sea to assess the rate of barnacle growth and phosphorus and nitrogen sequestration on burlap sheets suspended vertically from a floating line. Burlap panels were collected weekly and the barnacles analyzed for Ca, total-P, inorganic-P, total-N, total-C, CaCO3, and organic matter content. After 44 days of growth, the barnacle mats weighed 7.4 kg m−2 on a dry weight basis, with 80% of the mass as shell material. The nutrient sequestration was 9.4 g P m−2 and 100 g N m−2. Approximately half of the P was inorganic and appears to be coprecipitated with the calcium carbonate shell material. Results indicate that harvesting barnacles grown on artificial substrate in the Salton Sea would not be an effective method for removing N or P from the lake because of the relative proportions of shell material and organic material.