2022 marked the third consecutive La Niña and extended the longest consecutive stretch of negative Oceanic Niño Index since 1998-2001. While physical and biological conditions in winter and spring largely adhered to prior La Niña conditions, summer and fall were very different. Similar to past La Niña events, in winter and spring coastal upwelling was either average or above average, temperature average or below average, salin...

In late 2020, models predicted that a strong La Niña would take place for the first time since 2013, and we assessed whether physical and biological indicators in 2021 were similar to past La Niñas in the California Current Ecosystem (CCE). The Pacific Decadal Oscillation and Oceanic Niño Index indeed remained negative throughout 2021; the North Pacific Gyre Oscillation Index, however, remained strongly negative. The seventh l...

The California Current System (CCS) has experienced large fluctuations in environmental conditions in recent years that have dramatically affected the biological community. Here we synthesize remotely sensed, hydrographic, and biological survey data from throughout the CCS in 2019–2020 to evaluate how recent changes in environmental conditions have affected community dynamics at multiple trophic levels. A marine heatwave forme...

The degree to which ecosystems are regulated through bottom‐up, top‐down, or direct physical processes represents a long‐standing issue in ecology, with important consequences for resource management and conservation. In marine ecosystems, the role of bottom‐up and top‐down forcing has been shown to vary over spatio‐temporal scales, often linked to highly variable and heterogeneously distributed environmental conditions. Ecosy...

Particles and aggregates created in the surface layers of the ocean are transported not only by gravity, but also by the horizontal and vertical advection of the surrounding water. Subduction, in particular, can transport organic matter from the surface ocean to the mesopelagic in a manner that is not likely to be detected by typical in situ carbon export measurements (e.g., sediment traps and 238 U‐ 234 Th disequilibrium). To...

The isotopic composition of dissolved O 2 ( 17 Δ) and the biological O 2 saturation from O 2 : Ar ratios were measured in the surface ocean during six cruises off the coast of southern California from November 2005 to August 2008 to determine rates of gross oxygen production (GOP), net oxygen production (NOP), and the NOP : GOP ratio (a measure of potential export efficiency). In the mixed layer, 17 Δ of dissolved O 2 ( 17 Δ d...

We examined the dominant patterns of variability in the fish fauna of the southern C alifornia C urrent based on a principal component ( PC ) analysis of the C alifornia C ooperative O ceanic F isheries I nvestigations ichthyoplankton data set, 1951–2008. Eighty‐six taxa were analyzed, including all ecologically dominant fish species, both exploited and unexploited. The first three PC s accounted for 20.5, 12.4 and 6.8% of the...

We constructed a simple non–steady‐state model of trophic cycling relationships in the California Current Ecosystem and tested its predictions of mesozooplankton fecal‐pellet export against vertical carbon‐flux measurements by the 234 Th method taken during Lagrangian experiments. To assess trophic relationships, we simultaneously measured 14 C‐primary production and chlorophyll‐based rate estimates of phytoplankton growth, mi...

During the 1995 monsoons, phytoplankton biomass was low over large areas of the Arabian Sea in spite of often high concentrations of inorganic nutrients, characteristics typical of high‐nutrient, lowchlorophyll (HNLC) areas. The objective of this study, a part of the Arabian Sea U.S. JGOFS program, was to elucidate controls of phytoplankton biomass and community structure in these areas, using primarily pigment‐based methods....

A recently described unicellular chlorophytic alga isolated from meromictic Mono Lake, California, occupies a niche that spans two environments: the upper oxic mixolimnion and the deeper anoxic and highly reducing monimolimnion. This organism, Picocystis sp. strain ML, accounts for nearly 25% of the primary production during the winter bloom and more than 50% at other times of the year. In incubations, it is heavily grazed by...

Some groups of marine bacteria within the Α‐proteobacteria are capable of anoxygenic photosynthesis in oxic environments. Their primary photosynthetic pigment is bacteriochlorophyll a (BacChl a ). The impact of these bacteria on flows of energy and carbon in the ocean has been difficult to ascertain in the past. Recently, however, Kolber et al. (2001) reported that such bacteria are abundant in the upper ocean and that these m...

The labile chlorophyll a (Chl a 1 ) degradation product, 13 2 , 17 3 ‐cyclopheophorbide a enol (CPP516), was only recently found in marine sediments, where it can contribute a significant fraction to solvent‐extractable sedimentary chlorins. We developed a new chromatographic method for the analysis of CPP516 to study its distribution and sources in the marine environment. We found high concentrations of CPP516 in surficial se...