Green macroalgal blooms have substantially altered marine community structure and function, specifically by smothering seagrasses and other primary producers that are critical to commercial fisheries and by creating anoxic conditions in enclosed embayments. Bottom-up factors are viewed as the primary drivers of these blooms, but increasing attention has been paid to biotic controls of species composition. In Washington State, USA, blooms are often dominated by Ulva spp. intertidally and Ulvaria obscura subtidally. Factors that could cause this spatial difference were examined, including competition, grazer preferences, salinity, photoacclimation, nutrient requirements, and responses to nutrient enrichment. Ulva specimens grew faster than Ulvaria in intertidal chambers but not significantly faster in subtidal chambers. Ulva was better able to acclimate to a high-light environment and was more tolerant of low salinity than Ulvaria. Ulvaria had higher tissue N content, chlorophyll, chlorophyll b: chlorophyll a, and protein content than Ulva. These differences suggest that nitrogen availability could affect species composition. A suite of five grazers preferred Ulva to Ulvaria in choice experiments. Thus, bottom-up factors allow Ulva to dominate the intertidal zone while resistance to grazers appears to allow Ulvaria to dominate the subtidal zone. While ulvoid algae are in the same functional-form group, they are not functionally redundant.

Toxic properties are more often associated with microalgal blooms than with macroalgal blooms, although herbivore deterrents are well known in macroalgae, and inhibition of invertebrate larval development by extracts from Ulva spp. has been suggested. This study was prompted from our observation that substantial discoloration of seawater occurred in small bays after mass desiccation‐induced mortality of Ulvaria obscura (Kützing) Gayral. We examined the effects of extracts from Ulva fenestrata Postels et Ruprecht and Ulvaria obscura on Fucus gardneri Silva zygote development, growth of Ulva and Ulvaria, epiphytic algal accumulation, and oyster larval development. Fucus zygote development was inhibited by extracts from both species, although the effects of Ulvaria extracts were significantly greater. Epiphytic algal accumulation and the growth of Ulva and Ulvaria were inhibited by extracts from both species. Oyster larval development was arrested by the presence of extracts from each species. We conclude that extracts from both Ulva fenestrata and Ulvaria obscura have allelopathic properties. The effects are more widespread and occur at lower concentrations for extracts from Ulvaria than Ulva. These properties could alter competitive interactions by inhibiting germination or development of algae and invertebrates.

The power industry has been grappling with regulatory uncertainty in relation to carbon since late 2004 when Australian state governments committed to the introduction of an emissions trading scheme. This article estimates the additional cost to electricity users associated with the sub‐optimal introduction of new power generating capacity given regulatory delays. We find the costs to be significant; under a business‐as‐usual electricity demand growth scenario, prices in 2020 would be about $8.60/MWh higher than necessary. We also find that costs to consumers are lower where complementary policies are introduced to encourage energy efficiency and renewable energy.

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Premium residential solar feed-in tariffs have come under considerable scrutiny in Australia over the past 12 months following a sharp rise in the uptake of subsidised PV units and subsidy cost blow-outs. Using New South Wales data, Nelson, Simshauser and Kelley (2011) demonstrated that the inherent design of premium 'gross' feed-in tariffs are regressive in nature and required reform. Since the publication of that article in Economic Analysis & Policy (September 2011 edition), feed-in tariff policies have been substantially wound back in all Australian jurisdictions except Queensland. In this article, we examine the 'net' feed-in tariff in Queensland and similarly find it to be a regressive form of taxation. We also examine the so-called 'merit order effect'a purported 'economic benefit' arising from premium feed-in tariffs. However, the evidence is clear that merit order effects must, by definition, be transient and above all, are not welfare enhancing.