SECULAR TRENDS AND INTRINSIC VARIABILITY OF THE ZOOPLANKTON OF THE CALIFORNIA CURRENT ECOSYSTEM
The emergence time of an underlying trend in a time series is directly related to the intrinsic variability of the property of interest. Most zooplankton populations show high variability on multiple scales, hence the emergence time is long, requiring decades of systematic sampling in order to detect underlying trends. Here we analyze the 75-year time series of mesozooplankton sampled by CalCOFI and analyzed taxonomically in the California Current Ecosystem (CCE) LTER site, supplemented by the 19-year time series of mesozooplankton analyzed by digital Zooscan, also by CCE-LTER. The data illustrate long-term secular changes in some taxa, but not in most, suggesting altered community structure that has implications for predator foraging success and C export. While the C biomass of total euphausiids has increased, this masks an important underlying distinction: mid-latitude euphausiids have increased, but low-latitude euphausiids have not, instead responding to low frequency variability dominated by the PDO. While appendicularians have increased progressively in C biomass over the past 7 decades, other pelagic tunicates have not. Pyrosomes irrupted in the Southern and Central California region in 2014, although such outbreaks previously waxed in the 1950s and 1960s and waned in the intervening decades. Evidence from the last 2 decades suggests a major increase in planktonic Rhizaria. The changes in the mesozooplankton of this major upwelling ecosystem do not correspond to expectations from a simple 1-D model of progressively increased ocean stratification.
Presentation Preference: Oral
Primary Presenter: Mark Ohman, Scripps Institution of Oceanography (mohman@ucsd.edu)
Authors:
Mark Ohman, Scripps Institution of Oceanography (mohman@ucsd.edu)
SECULAR TRENDS AND INTRINSIC VARIABILITY OF THE ZOOPLANKTON OF THE CALIFORNIA CURRENT ECOSYSTEM
Category
Scientific Sessions > SS27 - Long-term perspectives in marine pelagic ecosystem research
Description
Time: 04:45 PM
Date: 30/3/2025
Room: W207AB