Establishing a captive kelp forest: Developments during the first year at the Monterey Bay Aquarium

Abstract

The Kelp Forest Tank at the Monterey Bay Aquarium represents a unique opportunity to study aspects of the development and maintenance of a kelp forest community under controlled conditions. The tank is 8.5 m deep, 20 m long and contains 1.2 million liters. Water motion is provided by an artificially produced standing wave (38 cm amplitude) and a flow rate of 8,800 liters of seawater per minute. During a typical day the tank receives an 80 - 20% mix of prefiltered and raw seawater drawn from a depth of 14 m. The tank is open to the sky and receives natural fluctuations in ambient light levels. Between October 1984 and August 1985, growth rates of transplanted adult plants of Macrocystis pyrifera ranged from 8 - 12 cm day-l (3 m frond). During the same time period, plants at a comparable depth off Hopkins Marine Station grew 10 - 14 cm day-l (3 m frond). The artificial rockwork in the tank was colonized rapidly. Fertile thalli of a variety of understory algae were used to seed the tank initially. Spores of other species of algae as well as invertebrate larvae were introduced with the raw seawater. Mean percent free space declined from nearly 100% to less than 5% between September 1984 and April 1985. Initial colonists were diatoms and filamentous brown algae, followed by a variety of erect algae (e.g. Fryeella, Gigartina, Ulva, Botryocladia). Comparisons of temperature and nutrient data between the Kelp Forest Tank and the field are presented.