Gema Parra

Feeding, physiology and growth responses in first-feeding gilthead seabream (Sparus aurata L.) larvae in relation to prey density

Abstract The effects of prey density (0.1, 1 and 10 rotifer ml −1 ) on feeding, oxygen uptake, growth, survival and energetic efficiencies in Sparus aurata larvae were investigated. Dry weights and total lengths at day 15 after hatching were similar in larvae fed with 10 and 1 rotifer ml −1 but were significantly higher than in larvae fed with 0.1 rotifer ml −1 . These differences were a consequence of a delay in starting feeding and growth in larvae fed with the lowest rotifer concentrations tested. Growth rates were similar in larvae fed on 0.1 and 1 rotifer ml −1 , while larvae fed with 10 rotifers ml −1 showed the smallest growth rate. Survival decreased markedly (from 91 to 7%) when prey density decreased. Ingestion rates of the actively feeding larvae increased with age at the three prey densities but larvae fed with 0.1 rotifer ml −1 showed lower ingestion rates. The specific oxygen uptake increased from hatching up to 35–40 μg dry weight; above this size the specific oxygen consumption remained almost constant. Survival at the end of the experimental period was closely related to the percentage of larvae able to start feeding at day 6. In larvae fed with 0.1 rotifer ml −1 , the energy ingested during the first days of feeding roughly met maintenance requirements. Therefore, the survival of larvae able to start feeding is not guaranteed at such low prey density.

Energy content of rotifers (Brachionus plicatilis and Brachionus rotundiformis) in relation to temperature

The effect of temperature on the chemical composition (carbon, nitrogenand ash content) and the energy content of the rotifers Brachionusplicatilis and Brachionus rotundiformis (formerly B. plicatilis L- andS-type respectively) was examined in experimental populations. Dry weightand carbon, nitrogen and hydrogen content remained practically unchanged inthe 20–35 °C range in B. rotundiformis, while in B.plicatilis the dry weight decreased slightly with increasing temperaturefrom 15 ° to 35 °C. Nevertheless, themajor source of variation was the fecundity status of the populations. Onthe other hand, B. rotundiformis showed higher energy content (joules per mgof dry matter) than B. plicatilis. This difference in energy content was dueto the different ash content because the organic matter of both species hadthe same energy content, as well as the same basic biomass composition.

Effects of Copper Sulfate on Growth, Development, and Escape Behavior in Epidalea calamita Embryos and Larvae

Epidalea calamita embryos at Gosner stages 3 and 19, and larvae at Gosner stage 25, were exposed to different copper sulfate concentrations, ranging from 0.05 to 0.40 mg Cu L−1, in 96-h acute toxicity tests. Embryonic and larval mortality, development, growth, and larval escape behavior were evaluated. LC50 at 96 h obtained at Gosner stages 3, 19, and 25 were 0.22, 0.08, and 0.11 mg Cu L−1, respectively. Embryonic and larval developments were delayed after 96 h of copper sulfate exposure. Growth was also affected and individuals in control treatments grew to twice the size of those exposed to copper concentrations over 0.2 mg Cu L−1 during the experiments initiated at Gosner stage 19. Escape behavior was altered after 96 h of copper sulfate exposure; larvae showed shorter distances moved and abnormal displacement types. However, after 4 days of recovery process, most of the larvae showed normal escape behavior. For amphibians that develop in temporary wetlands, increased development time, lower size, and altered escape behavior might have repercussions on the number of individuals that can successfully complete metamorphosis and, consequently, on recruitment.

Wetlands classification for amphibian conservation in Mediterranean landscapes

Habitat fragmentation and alteration have been described as the major factors relating to the decline observed in several amphibian species. In Spain, these processes are mainly associated with the large agricultural land area, the widespread use of toxic substances, and the agricultural practices used. All these aggressions affect wetlands and their watersheds, which are essential aquatic systems for many amphibian species. In an effort to discover where conservation and specific action plans could be more necessary, this study relates the amphibian richness in 28 representative Mediterranean wetlands to their characteristics and the activities carried out on their watershed. The required information considers diverse wetland variables. Our results show that watershed habitat heterogeneity is significantly positively correlated with amphibian richness, while the percentage of the watershed area devoted to olive cultivation is negatively correlated with it. The results allow us to classify wetlands according to their importance for amphibian conservation. Our results also show that 80% of the studied wetlands need specific action plans. Especially, more sustainable cultivation methods are required considering drastic changes in current agricultural practices. Finally, our data provides a baseline to understand future alterations due to agricultural practices.

Respiration rates in late eggs and early hatchlings of the common octopus, Octopus vulgaris

Respiration rates during late embryonic development and hatchlings of Octopus vulgaris were measured at 20°C. Oxygen consumption rates increased suddenly at hatching, in response to the increase in energetic expenditure due to their constant swimming activity by means of jet propulsion. Estimates indicate that hatchlings consumed three times more oxygen than the embryos at late stages. Chemical composition analysis revealed a relatively high nitrogen content (11%) in 0. vulgaris hatchlings with an energy content of 1.09 ±0.03 J mg dry matter -1 . Specific oxygen consumption in unfed O. vulgaris hatchlings reached values around 0.18 nmol O 2 μg -1 h -1 . It was estimated that the oxygen consumption of a medium-size egg mass of O. vulgaris is approximately twice than the oxygen uptake of the respective brooding female.

Effect of temperature, food and individual variability on the embryonic development time and fecundity of Arctodiaptomus salinus (Copepoda: Calanoida) from a shallow saline pond

Organisms living in temporary and shallow wetlands are adapted to survive in very fluctuating and unpredictable conditions and might help us to understand life cycle strategies and plasticity in the context of global warming. Despite the importance of Arctodiaptomus salinus in these systems, little is known about the effect of temperature on its population dynamics. Through an individual-based experimental protocol, we studied the effect of this factor and food on its reproduction. This approach has revealed a large range of variability in reproductive parameters in all the experimental conditions. Temperature positively affected egg production and negatively longevity, but did not affect clutch size. Under unsuitable food conditions, the clutch size decreased and the inter-clutch period increased, and when the food conditions improved, the number of eggs increased gradually in every clutch. Eggs from the same clutch hatched synchronously. In contrast, there were significant differences between the hatching times of clutches from different females and between those of the same female. The observed individual variability increased when temperature moved away from the medium values. The thermal tolerance threshold for A. salinus development might be around 25–29°C. Since water pond is close to this thermal limit for long periods of time, an increment of temperature because of global warming might have dramatic consequences on this population. The individual-based experimental approach of this study provides useful information to construct realistic individual-based models, which will help us to better understand the population-level consequences of individual variability in A. salinus reproduction.

Larval escape behavior in anuran amphibians as a wetland rapid pollution biomarker

Biomarkers represent a promising tool as “early-indicators” of potential pollutant impacts, providing the link between individuals’ responses and higher hierarchical levels, such as populations and communities. In this study we use alteration of escape behavior, caused by exposure to typical agrochemicals, as a biomarker of wetland pollution. Tadpoles from three different Iberian anuran species were exposed to sublethal concentrations of copper sulfate and ammonium nitrate for 96 h. Different behavioral indicators were then monitored: number of stimuli to provoke a displacement, distance moved, and nature of escape movement. All species showed similar behavioral alterations. The endpoints of all the three behavioral indices showed deficits leading to a reduction in the capacity and efficiency of escape. The recovery when larvae were moved to clean water was surprisingly fast. After 96 h in recovery, almost all larvae showed normal escape behavior. This indicates that this larval behavioral biomarker can be used as a warning tool in wetland biomonitoring programs in a continuous runoff or spill pollution context.

Tweet if you want to be sustainable: a thematic analysis of a Twitter chat to discuss sustainability in nurse education.

AIM To explore the concept of sustainability in nursing using social media as a vehicle for discussion on the topic. BACKGROUND There is a need for an increased awareness among nurses of the issues that are crucial for the healthcare sector to prepare for climate change and contribute to sustainable development. However, topics about sustainability and climate change are not a requirement of nursing curricula in Europe; social media provides an opportunity to raise issues and promote discussion. DESIGN A thematic analysis of a Twitter discussion. METHODS A Twitter discussion session hosted by @WeNurses took place on 24 March 2015 over 1 hour. Data were gathered via this online discussion hosted on Twitter, a social media platform. Following the discussion a thematic analysis of the posted Tweets was conducted. FINDINGS One hundred and nineteen people posted nine hundred and ninety six Tweets, a reach of 3,306,368. Tweets broadly followed the questions posted by the team. Several threads related to the sustainable use of healthcare resources and the need to reduce waste was evident. A Word Cloud of the Tweets highlighted prominent words in the discussion: sustainability, nursing/nurses, curriculum, important, waste, practice, resources, student, plastic, health, gloves. CONCLUSION Social media is an effective way of engaging nurses and students in a discussion on challenging issues. Sustainability appears to be important for nurses, with a particular emphasis on resource use and the importance of sustainability topics in nurse education.

Effects of previous sublethal pulse to ammonium nitrate on mortality and total length on Epidalea calamita larvae

Ammonium nitrate is one of the most widespread contaminants related with the viability of natural amphibian populations. In this study we have evaluated in terms of mortality and total length the effects that a previous sublethal pulse to ammonium nitrate generates in Epidalea calamita. Experiments were divided in two phases. In the first one, tadpoles were exposed to two different treatments, with and without a low ammonium nitrate concentration (22 mg NH(4)NO(3) L(-1)). The second phase consisted in static toxicity experiments from both origin treatments with five different nominal concentrations (0, 22, 45, 90 and 180 mg NH(4)NO(3) L(-1)). Results showed that tadpoles that had experienced a previous sublethal exposure showed a negative effect on survival (57% of reduction in the LC(50) value) and total length, throughout an increase in their sensitivity. These results could help us to understand the situation of amphibian populations inhabiting aquatic ecosystems exposed to discontinuous and variable pulses of pollutants.

Sedimentation of phosphorus fractions and temporal variation in the C:P ratio in La Concepción reservoir, southern Spain

Abstract The settling flux and content of organic carbon (C), organic matter, and different phosphorus (P) fractions were measured fortnightly during a 6‐month stratified period (from early April to early November) with sediment traps located at five different depths in La Concepcion, a mesotrophic and P‐limited reservoir in southern Spain. Characterisation of P fractions in the collected material was performed by a sequential extraction procedure. Sedimentation rates exhibited a distinct seasonal pattern, that allowed us to differentiate three periods: (1) a biogenic sedimentation period (BS), in which the sedimentation rates and total suspended matter concentration were lowest and the result of material of autochthonous origin; (2) a calcium carbonate precipitation period (CCP), in which there were high calcium concentrations in the settling seston; and (3) a rainfall period (R), in which the highest sedimentation rates occurred. Organic C, organic matter, and organic P content were highest in the settling material during the BS period and lowest during the R period. However, during the R period, inorganic‐P sedimentation rates were highest and the major P fraction was apatite‐P. Total organic, and inorganic (Fe‐ and Al‐bound and apatite) P, increased substantially, whereas total and organic C decreased with depth in the material collected by sediment traps during the BS and CCP periods. Consequently, the total C:P (Ct:Pt) and organic C:P (Corg:Porg) ratios decreased significantly with increasing depth of sediment traps.