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Abstract Feeding habits of herbivorous fishes play an important role in shaping the form and function of coastal marine ecosystems. Rabbitfishes (Siganidae) are important consumers of macroalgae on Indo‐West Pacific coral reefs. However, it is unclear how their diet varies among and within species at biogeographical scales, casting doubt on their precise functional roles across different regions. The present study assessed the inter‐ and intra‐specific diet variation of four rabbitfishes (Siganus trispilos, Siganus corallinus, Siganus virgatus and Siganus doliatus) factored by morphological relatedness among populations from Ningaloo Reef (western Australia), the Great Barrier Reef (GBR, eastern Australia) and the Yaeyama Islands (Okinawa Prefecture, Japan). Results showed that the region had a strong effect on diet, effectively reducing the expected effect of morphologic similitude. While intra‐specific differences were only significant when populations inhabited different regions; interspecific differences were not as predicted, with different morphotypes having similar diets when populations inhabited the same regions. Rabbitfishes consumed more corticated and filamentous macroalgae on the GBR, more foliose and membranous macroalgae at the Yaeyama Islands, and more leathery macroalgae at Ningaloo Reef. The findings indicate that rabbitfishes have high diet plasticity, and hence their functional role as mediators of competition between macroalgae and corals can change across biogeographic regions. Local context is therefore important when assessing the diet and functional role of herbivorous fishes. As climate change unfolds, shifts in the distribution, trophic behaviour and function of species are expected, making the study of trophic plasticity more important.

The corallivorous crown-of-thorns starfish (Acanthaster spp.) is a major cause of coral mortality on Indo-Pacific reefs. Despite considerable research into the biology of crown-of-thorns starfish, our understanding of the early post-settlement life stage has been hindered by the small size and cryptic nature of recently settled individuals. Most growth rates are derived from either laboratory studies or field studies conducted in Fiji and Japan. The Great Barrier Reef (GBR) is currently experiencing its fourth recorded outbreak and population models to inform the progression of outbreaks lack critical growth rates of early life history stages. High numbers of 0+ year juveniles (n = 3532) were measured during extensive surveys of 64 reefs on the northern GBR between May and December 2015. An exponential growth model was fitted to the size measurement data to estimate monthly ranges of growth rates for 0+ year juveniles. Estimated growth rates varied considerably and increased with age (e.g., 0.028–0.041 mm·day−1 for one-month-old juveniles versus 0.108–0.216 mm·day−1 for twelve-month-old juveniles). This pioneering study of 0+ year juveniles on the GBR will inform population models and form the basis for more rigorous ongoing research to understand the fate of newly settled Acanthaster spp.

Cyclooxygenase and lipoxygenase metabolism of arachidonic acid produces compounds important in cardiovascularcontrol. Further, arachidonic acid can be metabolised by cytochrome p450 to produce epoxyeicosatrienoicacids (EETs). These derivatives are inactivated by soluble epoxide hydrolase (sEH). The potentialrole of these EETs in hypertension and cardiac remodelling has been determined using the selective sEHinhibitor, N-adamantyl-N'-dodecylurea (ADU), in deoxycorticosterone acetate (DOCA)-salt hypertensive rats.Experiments were performed on male Wistar rats following uninephrectomy alone (UNX rats) or uninephrectomywith administration of DOCA (25 mg every fourth day subcutaneously) and 1% NaCl in drinking water(DOCA-salt rats). ADU (10 mg/kg/d subcutaneously) was administered for 2 wk starting 2 wk after surgery.Cardiovascular structure and function were determined using organ wet weights, histological analysis of collagenand inflammation, isolated heart and thoracic aortic ring preparations, and electrophysiological measurements.DOCA-salt hypertensive rats developed hypertension, hypertrophy, perivascular and interstitial fibrosis,endothelial dysfunction, and prolongation of the cardiac action potential duration within 4 wk. Administrationof ADU prevented the further increase in systolic blood pressure and left-ventricular wet weight and normalizedendothelial function. ADU treatment did not change inflammatory cell infiltration, collagen deposition, orcardiac action potential duration. EETs may be involved in the development of hypertension and endothelialdysfunction in DOCA-salt rats, but not in excessive collagen deposition or electrophysiological abnormalities. [ABSTRACT FROM AUTHOR]