Reproductive phenology and morphology of Macrocystis pyrifera (Laminariales, Ochrophyta) from southern New Zealand in relation to wave exposure.

Macrocystis pyrifera is a major habitat forming kelp in coastal ecosystems of temperate regions of the northern and southern hemispheres. We investigated the seasonal occurrence of adult sporophytes, morphological characteristics, and reproductive phenology at two sites within a wave-protected harbour and two wave-exposed sites in southern New Zealand every 3-4 months between 2012 and 2013. Seasonality in reproduction was assessed via the number of sporophylls, the occurrence of sori on sporophylls, and non-sporophyllous laminae (fertile pneumatocyst-bearing blades and fertile apical scimitars), meiospore release, and germination.

Nitrogen sufficiency enhances thermal tolerance in habitat-forming kelp: implications for acclimation under thermal stress.

Local and global changes associated with anthropogenic activities are impacting marine and terrestrial ecosystems. Macroalgae, especially habitat-forming species like kelp, play critical roles in temperate coastal ecosystems. However, their abundance and distribution patterns have been negatively affected by warming in many regions around the globe.

Responses of macroalgae to CO enrichment cannot be inferred solely from their inorganic carbon uptake strategy.

Increased plant biomass is observed in terrestrial systems due to rising levels of atmospheric CO, but responses of marine macroalgae to CO enrichment are unclear. The 200% increase in CO by 2100 is predicted to enhance the productivity of fleshy macroalgae that acquire inorganic carbon solely as CO (non-carbon dioxide-concentrating mechanism [CCM] species-i.e.

Copper pollution exacerbates the effects of ocean acidification and warming on kelp microscopic early life stages.

Ocean warming (OW), ocean acidification (OA) and their interaction with local drivers, e.g., copper pollution, may negatively affect macroalgae and their microscopic life stages.

Growth, ammonium metabolism, and photosynthetic properties of Ulva australis (Chlorophyta) under decreasing pH and ammonium enrichment.

The responses of macroalgae to ocean acidification could be altered by availability of macronutrients, such as ammonium (NH4+). This study determined how the opportunistic macroalga, Ulva australis responded to simultaneous changes in decreasing pH and NH4+ enrichment. This was investigated in a week-long growth experiment across a range of predicted future pHs with ambient and enriched NH4+ treatments followed by measurements of relative growth rates (RGR), NH4+ uptake rates and pools, total chlorophyll, and tissue carbon and nitrogen content.

Ocean acidification and kelp development: Reduced pH has no negative effects on meiospore germination and gametophyte development of Macrocystis pyrifera and Undaria pinnatifida.

The absorption of anthropogenic CO by the oceans is causing a reduction in the pH of the surface waters termed ocean acidification (OA). This could have substantial effects on marine coastal environments where fleshy (non-calcareous) macroalgae are dominant primary producers and ecosystem engineers. Few OA studies have focused on the early life stages of large macroalgae such as kelps.

Seawater pH, and not inorganic nitrogen source, affects pH at the blade surface of Macrocystis pyrifera: implications for responses of the giant kelp to future oceanic conditions.

Ocean acidification (OA), the ongoing decline in seawater pH, is predicted to have wide-ranging effects on marine organisms and ecosystems. For seaweeds, the pH at the thallus surface, within the diffusion boundary layer (DBL), is one of the factors controlling their response to OA. Surface pH is controlled by both the pH of the bulk seawater and by the seaweeds' metabolism: photosynthesis and respiration increase and decrease pH within the DBL (pH ), respectively.

Meiospores produced in sori of nonsporophyllous laminae of Macrocystis pyrifera (Laminariales, Phaeophyceae) may enhance reproductive output.

Different lamina of Macrocystis pyrifera sporophytes (i.e., sporophylls, pneumatocyst-bearing blades, and apical scimitars) in a wave-sheltered site were found to be fertile.