Asynchronous shifts in the demographics of two wave-swept kelp species (Laminariales) after nearly four decades.

Kelp forests are among the most abundant and productive marine ecosystems but are under threat from climate change and other anthropogenic stressors. Although knowledge is growing about how the abundance and distribution of kelp forests are changing, much less is known about the "non-lethal" effects that global change is having on the performance and health of kelp populations in areas where they persist. Here we assessed the age distribution of two common stipitate kelp species, Laminaria setchelli and Pterygophora californica, at Wizard Islet in Barkley Sound, British Columbia, Canada, and compared these data to historical demographic data collected by De Wreede (1984) and Klinger and DeWreede (1988) from the same site between 1981 and 1983.

Population genomics reveals strong impacts of genetic drift without purging and guides conservation of bull and giant kelp.

Kelp forests are declining in many parts of the northeast Pacific. In small populations, genetic drift can reduce adaptive variation and increase fixation of recessive deleterious alleles, but natural selection may purge harmful variants. To understand evolutionary dynamics and inform restoration strategies, we investigated genetic structure and the outcomes of genetic drift and purging by sequencing the genomes of 429 bull kelp (Nereocystis luetkeana) and 211 giant kelp (Macrocystis sp.

Ocean weather, biological rates, and unexplained global ecological patterns.

As on land, oceans exhibit high temporal and spatial temperature variation. This "ocean weather" contributes to the physiological and ecological processes that ultimately determine the patterns of species distribution and abundance, yet is often unrecognized, especially in tropical oceans. Here, we tested the paradigm of temperature stability in shallow waters (<12.

Microclimate predicts kelp forest extinction in the face of direct and indirect marine heatwave effects.

Marine heatwaves threaten the persistence of kelp forests globally. However, the observed responses of kelp forests to these events have been highly variable on local scales. Here, we synthesize distribution data from an environmentally diverse region to examine spatial patterns of canopy kelp persistence through an unprecedented marine heatwave.

Environmental heterogeneity mediates scale-dependent declines in kelp diversity on intertidal rocky shores.

Biodiversity loss is driven by interacting factors operating at different spatial scales. Yet, there remains uncertainty as to how fine-scale environmental conditions mediate biological responses to broad-scale stressors. We surveyed intertidal rocky shore kelp beds situated across a local gradient of wave action and evaluated changes in kelp diversity and abundance after more than two decades of broad scale stressors, most notably the 2013-2016 heat wave.

Ecology and Evolution of Phenotypic Plasticity in the Penis and Cirri of Barnacles.

Most barnacles are sessile, simultaneous hermaphrodites that reproduce by copulation. This is achieved through the extension of a muscular penis, famous for being the proportionally largest in the animal kingdom. The penis is a long cylindrical or conical organ, composed of a series of folded rings, allowing it to stretch to great lengths.

Interpopulational variation in the cold tolerance of a broadly distributed marine copepod.

Latitudinal trends in cold tolerance have been observed in many terrestrial ectotherms, but few studies have investigated interpopulational variation in the cold physiology of marine invertebrates. Here, the intertidal copepod Tigriopus californicus was used as a model system to study how local adaptation influences the cold tolerance of a broadly distributed marine crustacean. Among five populations spanning 18° in latitude, the following three metrics were used to compare cold tolerance: the temperature of chill-coma onset, the chill-coma recovery time and post-freezing recovery.

Something Darwin didn't know about barnacles: spermcast mating in a common stalked species.

Most free-living barnacles are hermaphroditic, and eggs are presumed to be fertilized either by pseudo-copulation or self-fertilization. Although the common northeast Pacific intertidal gooseneck barnacle, Pollicipes polymerus, is believed only to cross-fertilize, some isolated individuals well outside penis range nonetheless bear fertilized eggs. They must therefore either self-fertilize or-contrary to all prior expectations about barnacle mating-obtain sperm from the water.

Modular phenotypic plasticity: divergent responses of barnacle penis and feeding leg form to variation in density and wave-exposure.

Traits can evolve both in response to direct selection and in response to indirect selection on other linked traits. Although the evolutionary significance of coupled traits (e.g.

Experimental evidence for latent developmental plasticity: intertidal whelks respond to a native but not an introduced predator.

Animals with highly inducible traits may show no inducible response when exposed to a related but wholly novel cue. This appears to be true for the intertidal whelk Nucella lamellosa faced with a voracious introduced predator. In the laboratory, we exposed whelks to effluent from two species of predatory crab, the native red rock crab Cancer productus and the invasive European green crab Carcinus maenas.

Precisely proportioned: intertidal barnacles alter penis form to suit coastal wave action.

For their size, barnacles possess the longest penis of any animal (up to eight times their body length). However, as one of few sessile animals to copulate, they face a trade-off between reaching more mates and controlling ever-longer penises in turbulent flow. We observed that penises of an intertidal barnacle (Balanus glandula) from wave-exposed shores were shorter than, stouter than, and more than twice as massive for their length as, those from nearby protected bays.