Change in avian functional fingerprints of a Neotropical montane forest over 100 years as an indicator of ecosystem integrity

Ecologically relevant traits of organisms in an assemblage determine an ecosystem's functional fingerprint (i.e., the shape, size, and position of multidimensional trait space). Quantifying changes in functional fingerprints can therefore provide information about the effects of diversity loss or gain through time on ecosystem condition and is a promising approach to monitoring ecological integrity. This, however, is seldom possible owing to limitations in historical surveys and a lack of data on organismal traits, particularly in diverse tropical regions. Using data from detailed bird surveys from 4 periods across more than a century, and morphological and ecological traits of 233 species, we quantified changes in the avian functional fingerprint of a tropical montane forest in the Andes of Colombia. We found that 78% of the variation in functional space, regardless of period, was described by 3 major axes summarizing body size, dispersal ability (indexed by wing shape), and habitat breadth. Changes in species composition significantly altered the functional fingerprint of the assemblage and functional richness and dispersion decreased 35–60%. Owing to species extirpations and to novel additions to the assemblage, functional space decreased over time, but at least 11% of its volume in the 2010s extended to areas of functional space that were unoccupied in the 1910s. The assemblage now includes fewer large-sized species, more species with greater dispersal ability, and fewer habitat specialists. Extirpated species had high functional uniqueness and distinctiveness, resulting in large reductions in functional richness and dispersion after their loss, which implies important consequences for ecosystem integrity. Conservation efforts aimed at maintaining ecosystem function must move beyond seeking to sustain species numbers to designing complementary strategies for the maintenance of ecological function by identifying and conserving species with traits conferring high vulnerability such as large body size, poor dispersal ability, and greater habitat specialization. Article impact statement: Changes in functional fingerprints provide a means to quantify the integrity of ecological assemblages affected by diversity loss or gain.     

Towards enhancing tidally-induced water renewal in coastal lagoons

Environmental Fluid Mechanics - In order to address the problem of limited water renewal in restricted lagoons of moderate size having at least two tidal inlets, a method is proposed to enhance...     

Fetoscopic myelomeningocoele closure: Is the scientific evidence enough to challenge the gold standard for prenatal surgery?

Since the completion of the Management of Myelomeningocoele Study, maternal-fetal surgery for spina bifida has become a valid option for expecting parents. More recently, multiple groups are exploring a minimally invasive approach and recent outcomes have addressed many of the initial concerns with this approach. Based on a previously published framework, we attempt to delineate the developmental stage of the surgical techniques. Furthermore, we discuss the barriers of performing randomized controlled trials comparing two surgical interventions and suggest that data collection through registries is an alternative method to gather high-grade evidence.     

Ultraviolet absorption in transparent zooplankton and its implications for depth distribution and visual predation

The use of transparency as camouflage in the epipelagic realm is complicated by the presence of ultraviolet radiation, because the presence of UV-protective pigments decreases UV transparency and may reveal transparent zooplankton to predators and prey with UV vision. During July 1999, September 1999, and June 2000, transparency measurements (from 280 to 500 nm) were made on living specimens of 15 epipelagic (collection depth: 0–20 m, average: 11 ± 1 m) and 19 mesopelagic (collection depth: 150–790 m, average: 370 ± 40 m) species of transparent zooplankton from Oceanographer Canyon and Wilkinson Basin in the Northwest Atlantic Ocean. In addition, measurements of downwelling irradiance (from 330 to 500 nm) versus depth were made. The tissues from epipelagic zooplankton had lower UV transparency than those from mesopelagic zooplankton, while the average visible transparency (at 480 nm) of the two groups was not significantly different. Percent transparency was positively correlated with wavelength over most of the measured range, with a rapid decrease below a certain cutoff wavelength. In mesopelagic tissues, the cutoff wavelength was generally 300 nm. In epipelagic tissues, the cutoff wavelength was between 300 and 400 nm. Twelve out of 19 epipelagic tissues had transparencies at 320 nm that were half or less than their 480 nm transparency values, versus only 4 out of 21 mesopelagic tissues. The effects of UV absorption on UV visibility and minimum attainable depth were modeled using contrast theory and the physics of light attenuation. Because UV absorption was generally significantly greater in the UVB than in the UVA spectrum (where UV vision occurs), and because the highest UV absorption was often found in less transparent individuals, its modeled effects on visibility were slight compared to its effects on minimum attainable depth. Received: 14 April 2000 / Accepted: 16 November 2000