Sanctuary Integrated Monitoring Network
Monitoring Project

Population Dynamics of Sessile Deep-sea Invertebrates in Monterey Bay

Principal Investigator(s)

  • Jim Barry
    Monterey Bay Aquarium Research Institute
  • Chris Lovera
    Monterey Bay Aquarium Research Institute


Start Date: September 05, 1994

The objectives of this study are to determine the rates of survival and reproduction of common benthic invertebrate megafauna that inhabit the continental slope in Monterey Bay. We deployed 15 lead-line transect lines 50 m long, which are marked in 1 m intervals. Transects were deployed at depths of 300, 600, and 900 m. These transect lines are used as guides to create maps of the local population of the mushroom coral (Anthomastus ritteri), Sessile sea cucumber (Psolus squamatus), and deep-sea brachiopod (Laqueus californianus). Repeated surveys of the transect lines allow us to determine which individuals have died, and note any new juvenile recruits to the population. Together, this information allows us to create life tables for each species at each location.

With knowledge of the life histories of individuals of deep-sea organisms, something that has not been accomplished to date, we will be able to determine rates of recruitment and survival, and compare how those vary among depths and locations. For example, we hope to determine whether changes in abundance with depth within Anthomastus is related to a change in recruitment rates or due to increased mortality in shallow (or deep) water.

Unfortunately, many (12 of 15) of the transect lines have been lost, apparently due to fishing activities. We have now nearly completed development of a deep-sea “Marker Tool”, which will be capable inserting small markers directly into some rock surfaces, so that we will be able to establish permanent markers that are not vulnerable to fishing activities.

Summary to Date

A single transect (MC945) analyzed since 1994 has revealed the recruitment and survival rates of 3 benthic invertebrates. Several hundred individuals of these species have been followed for several years. Survival rates are typically high, but we have detected significant low survival rates for Anthomastus ritteri, particularly during the past 1-2 years, when only ~80% of the survey population survived. While Anthomastus experienced low survival rates, annual survival for Psolus and Laqueus were 100, and 95%, respectively. We do not know why these species experienced different rates of survival. Recruitment rates (individuals growing to a size of ~1 cm) has been very low for all species.

Study Parameters

  • Dispersal & Recruitment
  • Mortality

Study Methods

more later

Figures and Images

Survival rate of Psolus squamatus.

Survival rate of Anthomastus ritteri.

Survival rate of Laqueus californianus.