Geographic variation in responses of kelp forest communities of the California Current to recent climatic changes

Abstract

The changing global climate is having profound effects on coastal marine ecosystems around the world. Structure, functioning, and resilience, however, can vary geographically, depending on species composition, local oceanographic forcing, and other pressures from human activities and use. Understanding ecological responses to environmental change and predicting changes in the structure and functioning of whole ecosystems require large-scale, long-term studies, yet most studies trade spatial extent for temporal duration. We address this shortfall by integrating multiple long-term kelp forest monitoring datasets to evaluate biogeographic patterns and rates of change of key functional groups (FG) along the west coast of North America. Analysis of data from 469 sites spanning Alaska, USA, to Baja California, Mexico, and 373 species (assigned to 18 FG) reveals regional variation in responses to both long-term (2006-2016) change and a recent marine heatwave (2014-2016) associated with two atmospheric and oceanographic anomalies, the "Blob" and extreme El Niño Southern Oscillation (ENSO). Canopy-forming kelps appeared most

The effects of depth and diet on red abalone growth and survival in cage mariculture at San Jeronimo Island, Baja California, Mexico

“…The latter does not create a floating canopy and requires scuba to harvest, whereas the canopy of M. pyrifera is easily harvested from the surface by hand from a boat. With future predictions of reduced wild populations of M. pyrifera in Baja California due to warmer temperatures or other environmental disturbances (Beas-Luna et al 2020), our results suggest, as previous studies, that E. arborea is a suitable alternative food source for red abalone aquaculture.…”

“…Two anchors (iron pipes 7.5 cm in diameter and 1.5 m long) were buried in the seabed at an angle of approximately 45º. Buoys (200-L drums with pressurized air) were attached to the anchors and distributed along the 100-m long float line (polypropylene 2020; Cavanaugh et al 2019;Beas-Luna et al 2020). Debido a la reciente variabilidad en la disponibilidad de biomasa de sargazo gigante, es de suma importancia evaluar otras macroalgas como fuentes alternativas de comida para la maricultura de abulón.…”

“…In the northeastern Pacific, abalone farms in Mexico and the USA typically use giant kelp, M. pyrifera, harvested from the wild as feed (Evans andLangdon 2000, Garcia-Esquivel andFelbeck 2009). However, in the last 2 decades extreme events such as ENSO and marine heatwaves have substantially affected giant kelp populations in Baja California (Ladah et al 1999;Arafeh-Dalmau et al 2019Cavanaugh et al 2019;Beas-Luna et al 2020). Because of the recent variability in giant kelp biomass availability, it is important to assess other macroalgae as alternative food sources for abalone mariculture.…”

Southward decrease in the protection of persistent giant kelp forests in the northeast Pacific

“…This region is subject to episodes of higher sea surface temperatures and lower availability of nutrients, limiting kelp biomass and area 30 . Kelp forests found near their warm-distribution limit are more impacted by extreme climatic events 24,[30][31][32] , suggesting that future climate-driven impacts could significantly diminish the coverage of kelp in Baja California. Protection of persistent kelp in the region can minimize other local stressors, such as indirect negative effects of fishing (through the removal of predators and release of herbivores that can over-graze kelp 33 ), maintain sources for recovery of impacted habitat patches, and build the resilience required for these ecosystems to adapt and persist in the face of future changes.…”

Effect of environmental history on the habitat-forming kelp Macrocystis pyrifera responses to ocean acidification and warming: a physiological and molecular approach

“…Kelp species seem to have evolved different physiological capabilities to deal with fluctuating environmental conditions, making it difficult to generalize how these organisms can respond to climate change 56 , 57 . For example, local adaptation to changes in nitrogen variability 58 , 59 , temperature 60 – 64 and pH 63 have been observed across isolated populations of kelps (i.e., Macrocystis pyrifera, Laminaria longicruris , Undaria pinnatifida).…”