Kelp forests as nursery and foundational habitat for reef fishes.

Conservation of marine biodiversity requires an understanding of the habitats needed to support and replenish species of interest. It also requires knowledge about the abundance and diversity of multispecies assemblages. Variation in the distribution and composition of kelp forests, one of the most productive marine coastal habitats globally, can have major influences on reef fishes-a group of ecologically and socioeconomically important species.

Variable coastal hypoxia exposure and drivers across the southern California Current.

Declining oxygen is one of the most drastic changes in the ocean, and this trend is expected to worsen under future climate change scenarios. Spatial variability in dissolved oxygen dynamics and hypoxia exposures can drive differences in vulnerabilities of coastal ecosystems and resources, but documentation of variability at regional scales is rare in open-coast systems. Using a regional collaborative network of dissolved oxygen and temperature sensors maintained by scientists and fishing cooperatives from California, USA, and Baja California, Mexico, we characterize spatial and temporal variability in dissolved oxygen and seawater temperature dynamics in kelp forest ecosystems across 13° of latitude in the productive California Current upwelling system.

Short- and long-term impacts of variable hypoxia exposures on kelp forest sea urchins.

Climate change is altering the intensity and variability of environmental stress that organisms and ecosystems experience, but effects of changing stress regimes are not well understood. We examined impacts of constant and variable sublethal hypoxia exposures on multiple biological processes in the sea urchin Strongylocentrotus purpuratus, a key grazer in California Current kelp forests, which experience high variability in physical conditions. We quantified metabolic rates, grazing, growth, calcification, spine regeneration, and gonad production under constant, 3-hour variable, and 6-hour variable exposures to sublethal hypoxia, and compared responses for each hypoxia regime to normoxic conditions.

Realistic losses of rare species disproportionately impact higher trophic levels.

Predicting the consequences of changes in biodiversity requires understanding both species' susceptibility to extirpation and their functional roles in ecosystems. However, few studies have evaluated the effects of realistic, non-random biodiversity losses, severely limiting the applicability of biodiversity research to conservation. Here, we removed sessile species from a rocky shore community in a way that deliberately mimicked natural patterns of species loss.