Subspecialty consultations in a teaching hospital.

A chart review of 60 consultations by the nephrology service of a teaching hospital was carried out to determine their diagnostic and therapeutic utility. General medicine residents on elective rotations in nephrology performed 72% of the consultations, only 26% being written by residents in the subspecialty. Consultants made an average of 2.2 diagnoses per patient, of which 57% confirmed the working diagnosis already in the medical record. They made an average of 3.0 recommendations for further investigation per patient, but referring physicians implemented only 58% of these. An average of 1.6 recommendations for therapy were made per patient, of which 64% were implemented. The apparent neglect of the consultant''s advice for investigation and therapy suggests that the written consultation to some extent fails to convey information useful for the referring physician and the patient. Further study is needed to determine if this failure reflects inadequate training of house officers as consultants.     

Habitat Selectivity and Reliance on Live Corals for Indo-Pacific Hawkfishes (Family: Cirrhitidae)

Hawkfishes (family: Cirrhitidae) are small conspicuous reef predators that commonly perch on, or shelter within, the branches of coral colonies. This study examined habitat associations of hawkfishes, and explicitly tested whether hawkfishes associate with specific types of live coral. Live coral use and habitat selectivity of hawkfishes was explored at six locations from Chagos in the central Indian Ocean extending east to Fiji in the Pacific Ocean. A total of 529 hawkfishes from seven species were recorded across all locations with 63% of individuals observed perching on, or sheltering within, live coral colonies. Five species (all except Cirrhitus pinnulatus and Cirrhitichthys oxycephalus) associated with live coral habitats. Cirrhitichthys falco selected for species of Pocillopora while Paracirrhites arcatus and P. forsteri selected for both Pocillopora and Acropora, revealing that these habitats are used disproportionately more than expected based on the local cover of these coral genera. Habitat selection was consistent across geographic locations, and species of Pocillopora were the most frequently used and most consistently selected even though this coral genus never comprised more than 6% of the total coral cover at any of the locations. Across locations, Paracirrhites arcatus and P. forsteri were the most abundant species and variation in their abundance corresponded with local patterns of live coral cover and abundance of Pocilloporid corals, respectively. These findings demonstrate the link between small predatory fishes and live coral habitats adding to the growing body of literature highlighting that live corals (especially erect branching corals) are critically important for sustaining high abundance and diversity of fishes on coral reefs.     

Diet and cross-shelf distribution of rabbitfishes (f. Siganidae) on the northern Great Barrier Reef: implications for ecosystem function

Herbivorous fishes are a critical functional group on coral reefs, and there is a clear need to understand the role and relative importance of individual species in reef processes. While numerous studies have quantified the roles of parrotfishes and surgeonfishes on coral reefs, the rabbitfishes (f. Siganidae) have been largely overlooked. Consequently, they are typically viewed as a uniform group of grazing or browsing fishes. Here, we quantify the diet and distribution of rabbitfish assemblages on six reefs spanning the continental shelf in the northern Great Barrier Reef. Our results revealed marked variation in the diet and distribution of rabbitfish species. Analysis of stomach contents identified four distinct groups: browsers of leathery brown macroalgae (Siganus canaliculatus, S. javus), croppers of red and green macroalgae (S. argenteus, S. corallinus, S. doliatus, S. spinus) and mixed feeders of diverse algal material, cyanobacteria, detritus and sediment (S. lineatus, S. punctatissimus, S. punctatus, S. vulpinus). Surprisingly, the diet of the fourth group (S. puellus) contained very little algal material (22.5 %) and was instead dominated by sponges (69.1 %). Together with this variation in diet, the distribution of rabbitfishes displayed clear cross-shelf variation. Biomass was greatest on inner-shelf reefs (112.7 ± 18.2 kg.ha^?1), decreasing markedly on mid- (37.8 ± 4.6 kg.ha^?1) and outer-shelf reefs (9.7 ± 2.2 kg.ha^?1). This pattern was largely driven by the browsing S. canaliculatus that accounted for 50 % of the biomass on inner-shelf reefs, but was absent in mid- and outer-shelf reefs. Mixed feeders, although primarily restricted to the reef slope and back reef habitats, also decreased in abundance and biomass from inshore to offshore, while algal cropping taxa were the dominant group on mid-shelf reefs. These results clearly demonstrate the extent to which diet and distribution vary within the Siganidae and emphasise the importance of examining function on a species-by-species basis.     

Detachment of Porites cylindrica nubbins by herbivorous fishes

A form of active restoration for coral assemblages involves culturing coral nubbins at nursery sites before transplantation to recipient reefs. Incidental grazing and/or directed predation by local fish assemblages are major sources of dislodgement and mortality for coral nubbins in nurseries. However, the rate of coral nubbin detachment, how this varies across fish taxa, and whether nubbin size affects rates of detachment warrant further investigation. We used field and aquaria experiments to examine the effect of incidental grazing and predation on the detachment of Porites cylindrica nubbins of different sizes (0.5, 1, 2, 3, 4, and 5 cm height). Short‐term (6 hours) exposure of nubbins to local fish assemblages at Lucero Reef, northwestern Philippines, caused higher detachment (1.93% ± 0.53 SE) compared to caged controls (0.16% ± 0.16 SE), with no detectable effect of nubbin size. To identify the impact of individual fish species, nubbins were exposed to one of four locally abundant herbivorous and corallivorous fish species in aquaria for 8 hours. Nubbin detachment was greater when exposed to Chlorurus spilurus (1.20–36.2%) and Siganus fuscescens (0.00–15.0%) than Chaetodon lunulatus (0.00–4.00%) and Chaetodon kleinii (0.00–1.20%), with the smallest nubbins (0.5 cm) being the most vulnerable. Our results suggest that incidental grazing by herbivorous fishes, especially parrotfishes, may potentially be an important source of detachment and likely mortality of nubbins. Optimizing coral nursery protocols should consider potential trade‐offs between excluding grazing fishes and the accumulation of algal material on caging structures to minimize nubbin mortality and improve coral restoration success.     

AMPA Receptor Activation Promotes Non-Amyloidogenic Amyloid Precursor Protein Processing and Suppresses Neuronal Amyloid-β Production

Soluble oligomeric amyloid β peptide (Aβ) generated from processing of the amyloid precursor protein (APP) plays a central role in the pathogenesis of Alzheimer''s Disease (AD) and through actions at glutamatergic synapses affects excitability and plasticity. The physiological control of APP processing is not fully understood but stimulation of synaptic NMDA receptors (NMDAR) can suppress Aβ levels through an ERK-dependent increase in α-secretase activity. AMPA-type glutamate receptors (AMPAR) couple to ERK phosphorylation independently of NMDAR activation raising the possibility that stimulation of AMPAR might similarly promote non-amyloidogenic APP processing. We have tested this hypothesis by investigating whether AMPAR directly regulate APP processing in cultured mouse cortical neurons, by analyzing APP C-terminal fragments (CTFs), soluble APP (sAPP), Aβ levels, and cleavage of an APP-GAL4 reporter protein. We report that direct stimulation of AMPAR increases non-amyloidogenic α-secretase-mediated APP processing and inhibits Aβ production. Processing was blocked by the matrix metalloproteinase inhibitor TAPI-1 but was only partially dependent on Ca²⁺ influx and ERK activity. AMPAR can therefore, be added to the repertoire of receptors that couple to non-amyloidogenic APP processing at glutamatergic synapses and thus pharmacological targeting of AMPAR could potentially influence the development and progression of Aβ pathology in AD.     

Macroalgae removal on coral reefs: realised ecosystem functions transcend biogeographic locations

Coral Reefs - Coral reef ecosystems are at the forefront of biodiversity loss and climate change-mediated transformations. This is expected to have profound consequences for the functioning of...     

Impaired growth and survival of tropical macroalgae (Sargassum spp.) at elevated temperatures

Increasing ocean temperatures associated with ongoing climate change have resulted in regional reductions in the cover of live coral and increasing concerns that coral reefs will be overgrown by macroalgae. The likelihood of macroalgal overgrowth will, however, depend on the thermal sensitivities of the macroalgae themselves. We exposed recently settled propagules of the common canopy-forming macroalga Sargassum swartzii and adult thalli of three species of Sargassum (S. swatzii, S. cristaefolium, S. polycystum) to three experimental temperatures: ambient, + 2 °C, and + 3.5 °C, reflective of summer minimum, mean, and maximum temperatures for the region. Growth and survival of Sargassum swartzii propagules were assessed over 48 days, and the growth, physical toughness, elemental composition, and susceptibility to herbivory of adult thalli were assessed after short-term exposure (2-weeks) to experimental temperatures. Growth and survival of S. swartzii propagules were reduced by 43% and 84%, respectively, when cultured at the elevated (+ 3.5 °C) temperature compared to ambient temperature. Similarly, elevated temperature resulted in a 17–49% decline in the growth of adult Sargassum thalli relative to controls. Susceptability of S. swartzii and S. cristaefolium to herbivory (i.e. mass removed by herbivores) was 50% less for thalli cultured at elevated (+ 3.5 °C) compared to ambient temperature, but this pattern was not related to changes in the physical or chemical properties of the thalli as a result of elevated temperature. The negative effects of elevated temperatures on the growth and survival of both Sargassum propagules and adult thalli will likely restrict the capacity of Sargassum, and potentially other macroalgae, to establish in new areas, and may also threaten the persistence of existing macroalgal meadows under future ocean temperatures. The thermal sensitivities of tropical Sargassum, together with those of corals, suggest ongoing ocean warming may lead to novel reef ecosystems that are low in both coral cover and macroalgal cover.

     

Influence of depth on sex-specific energy allocation patterns in a tropical reef fish

The effect of depth on the distribution and sex-specific energy allocation patterns of a common coral reef fish, Chrysiptera rollandi (Pomacentridae), was investigated using depth-stratified collections over a broad depth range (5–39 m) and a translocation experiment. C. rollandi consistently selected rubble habitats at each depth, however abundance patterns did not reflect the availability of the preferred microhabitat suggesting a preference for depth as well as microhabitat. Reproductive investment (gonado-somatic index), energy stores (liver cell density and hepatocyte vacuolation), and overall body condition (hepato-somatic index and Fulton’s K) of female fish varied significantly among depths and among the three reefs sampled. Male conspecifics displayed no variation between depth or reef. Depth influenced growth dynamics, with faster initial growth rates and smaller mean asymptotic lengths with decreasing depth. In female fish, relative gonad weight and overall body condition (Fulton’s K and hepato-somatic index) were generally higher in shallower depths (≤10 m). Hepatic lipid storage was highest at the deepest sites sampled on each reef, whereas hepatic glycogen stores tended to decrease with depth. Depth was found to influence energy allocation dynamics in C. rollandi. While it is unclear what processes directly influenced the depth-related patterns in energy allocation, this study shows that individuals across a broad depth gradient are not all in the same physiological state and may contribute differentially to the population reproductive output. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Abundance,diversity, and feeding behavior of coral reef butterflyfishes at Lord Howe Island

Endemic species are assumed to have a high risk of extinction because their restricted geographic range is often associated with low abundance and high ecological specialization. This study examines the abundance of Chaetodon butterflyfishes at Lord Howe Island in the south‐west Pacific, and compares interspecific differences in local abundance to the feeding behavior and geographic range of these species. Contrary to expected correlations between abundance and geographic range, the single most abundant species of butterflyfish was Chaetodon tricinctus, which is endemic to Lord Howe Island and adjacent reefs; densities of C. tricinctus (14.1 ± 2.1 SE fish per 200m²) were >3 times higher than the next most abundant butterflyfish (Chaetodon melannotus), and even more abundant than many other geographically widespread species. Dietary breadth for the five dominant butterflyfishes at Lord Howe Island was weakly and generally negative correlated with abundance. The endemic C. tricinctus was a distinct outlier in this relationship, though our extensive feeding observations suggest some issues with the measurements of dietary breadth for this species. Field observations revealed that all bites taken on benthic substrates by C. tricinctus were from scleractinian corals, but adults rarely, if ever, took bites from the benthos, suggesting that they may be feeding nocturnally and/or using mid‐water prey, such as plankton. Alternatively, the energetic demands of C. tricinctus may be fundamentally different to other coral‐feeding butterflyfishes. Neither dietary specialization nor geographic range accounts for interspecific variation in abundance of coral reef butterflyfishes at Lord Howe Island, while much more work on the foraging behavior and population dynamics of C. tricinctus will be required to understand its’ abundance at this location.