Fungal diversity in coffee plantation systems and in a tropical montane cloud forest in Veracruz,Mexico

We compared the abundance, species richness and diversity of saprobic filamentous microfungi in the forest and in coffee plantation systems (with different biophysical structures of the vegetation and agricultural management) and evaluated the degree of similarity in species composition among these sites. Soil washing was used to isolate the saprobic filamentous microfungi. Emerging colonies were quantified and transferred to tubes with culture medium and then mounted on semi-permanent slides for identification under the microscope. From 90 samples and 4,500 inoculated soils particles, 415 species were distinguished. The genera Trichoderma, Penicillium, Fusarium, Chaetomium and Humicola were the most frequent in all study sites. The transformation of the tropical montane cloud forest in coffee plantation had no significant effect on the abundance, species richness and diversity of the saprobic filamentous microfungi. Effects of the biophysical structures of the vegetation and the agricultural management of the sites were only detected at the level of dominant genera (Fusarium, Trichoderma and Penicillium) and on the evenness. The low degree of similarity among the six sites suggests the existence of a high exchange of species.     

Species distribution models applied to plant species selection in forest restoration: are model predictions comparable to expert opinion?

An expert on local flora usually is the best option for plant species selection in most ecological restoration projects; although species selection often needs to be dealt with swiftly as well as on a limited budget, and obtaining the opinion of a local expert may not always be an economically viable alternative. In such cases, species distribution models (SDM) may offer a faster and more cost effective alternative. We asked six experts to rank native tree species according to their suitability at 24 forest sites. The predictive performance of the suitability rankings was evaluated by assessing their ability to discriminate present from absent species in the observed tree assemblages at each evaluation site. We used the area under the receiver operating characteristic curve to calculate the probability that the estimated suitability for a species present at a particular evaluation site is greater than the estimate for an absent species (both picked at random). Suitability rankings were also obtained from the predictions of SDM and the same procedure was used to estimate the predictive performance of the set of models at each site. The experts offered concordant suitability rankings at almost every evaluation site. There were no significant differences in the predictive performance of the SDM and four of the experts, although the SDM performed slightly better than the other two experts. Our results point to the suitability of the proposed species distribution modeling approach to obtain fast and cost effective recommendations for species selection in forest restoration projects.     

Digestive enzyme activity during early larval development of the Cuban gar Atractosteus tristoechus

The ontogenesis of digestive enzymes (proteases, amylases, lipases, and phosphatases) in Cuban gar Atractosteus tristoechus was determined in larvae between 5 and 18 days after hatching (DAH). Variations in specific activities of most enzymes were related to the transition from endogenous to exogenous feeding and to the transition from the larval to the juvenile stage. Alkaline protease activity was not detected until 8 DAH in contrast to acid protease activity, which was quantifiable at 5 DAH. Acid protease activity was consistently higher than alkaline protease activity, indicating the presence of a functional stomach in the early stages of larval development. The acid protease activities of larvae and adults were compared by means of zymogram analysis. Four acid protease bands were found in adults (two more than in larvae). This result is the first time that more than one band of acid proteolytic activity has been found in Lepisosteidae. High lipase activity indicated the importance of lipid utilization, particularly during yolk-sac absorption. In contrast to the other enzymes studied, amylase activity was consistently low, probably due to the strictly carnivorous diet of gar larvae and their low capacity for carbohydrate digestion. High activities of aminopeptidase and acid and alkaline phosphatases suggest intestinal absorption. This result, together with the existence of a short gut and a lower proteolytic activity in the intestine than in the stomach, suggest that most of the proteolytic activity takes place in the stomach, while the primary function of the intestine is nutrient uptake.     

Effect of hypo- and hyper-saline conditions on osmolarity and fatty acid composition of juvenile shrimp Litopenaeus vannamei (Boone, 1931) fed low- and high-HUFA diets

Litopenaeus vannamei (Boone) grown in ponds are exposed to salinities of less than 5 g L^?1 during inland shrimp culture or to more than 40 g L^?1 from evaporation and reduced water exchange in dry, hot climates. However, dietary requirements for shrimp grown in low or high salinities are not well defined, particularly for fatty acids. Feeding shrimp postlarvae with highly unsaturated fatty acids (HUFA) enhances tolerance to acute exposure to low salinity, as a result of better nutritional status, or/and specific effects of HUFA on membrane function and osmoregulation mechanisms. This study analysed the effect of HUFA supplementation (3% vs. 34%) on L. vannamei juveniles reared for 21 days at low (5 g L^?1), medium (30 g L^?1) and high salinities (50 g L^?1). Juveniles grown at 5 g L^?1 had lower survival compared with controls (30 g L^?1) or shrimp grown at 50 g L^?1, but no significant effect on survival was observed as a result of HUFA enrichment. In contrast, growth was significantly lower for shrimp grown at 50 g L^?1, but this effect was compensated by the HUFA‐enriched diet. Osmotic pressure in haemolymph was affected by salinity, but not by HUFA enrichment. Shrimp fed HUFA‐enriched diets had significantly higher levels of eicosapentaenoic acid and docosahexaenoic acid in hepatopancreas and gills. These results demonstrate that growth at high salinities is enhanced with diets containing high HUFA levels, but that HUFA‐enriched diets have no effect on shrimp reared at low salinities.     

Efficacy of furunculosis vaccines in turbot, Scophthalmus maximus (L.): evaluation of immersion, oral and injection delivery

The commercial furunculosis vaccine Aquavac Furovac 5 and an autogenous vaccine, based on the challenge strain, induced immune protection in turbot, Scophthalmus maximus (L.), as shown in challenge tests 120 days post-immunization by injection (relative percentage of survival, RPS = 72-99%). This protective effect lasted for at least 6 months post-immunization at appreciable levels (RPS = 50-52%). Neither the autogenous vaccine nor the commercial vaccine was able to induce significant levels of protection against Aeromonas salmonicida in turbot when administered by immersion. Antibody levels were high or moderate in fish vaccinated by injection with the different vaccines and very low in fish vaccinated by immersion. The field results show that delivering an oral boost after the primary vaccination by injection did not enhance protection of turbot against furunculosis and that water-based (autogenous vaccine) and oil adjuvanted (Alpha Ject 1200) vaccines administered by injection conferred similar levels of protection (RPS > 80%) in turbot.     

Genetic structure of Orbicella faveolata population reveals high connectivity among a marine protected area and Varadero Reef in the Colombian Caribbean

1. The protection of ecosystems with high diversity, such as coral reefs, is not an approach that guarantees their conservation. Thus, maintaining connectivity among coral populations over the long term is a strategy that should be adopted in order to protect diversity and ecological processes. Although coral reefs in Colombia are highly diverse, the population genetics baseline data of keystone species such as Orbicella faveolata are limited.
2. To provide current information about the connectivity between populations of O. faveolata in the Colombian Caribbean, the genetic diversity and distribution of O. faveolata was evaluated with analysis of molecular variance (AMOVA), principal components, and migration estimations using 113 genets distributed in six populations. Also, a genetic structure analysis that included the available data for the Caribbean population was conducted, seeking to understand how the Colombian populations relate to the broader region.
3. According to the global fixation index (F_ST) for the Colombian Caribbean, there was no genetic structure (F_ST = 0.002). Discriminant analysis of principal components (DAPC) showed that Corales del Rosario Archipelago (CR), Este de Isla Fuerte (EIF), San Bernardo Archipelago (SB), and Varadero Reef (VR) were grouped with Oeste de Isla Fuerte (OIF), with Bushnell (BS) representing the most divergent cluster. Migration analysis showed relatively high migration from VR to CR and SB, highlighting the importance of VR as a genetic reservoir for the region. Structure analysis showed that the Colombian population presented a specific genetic identity (F_ST = 0.254), suggesting that the Colombian Caribbean population could be a peripheral population that contributes significantly to genetic variation and is connected through a complex connectivity process.
4. In conclusion, the estimated genetic connectivity reflects the influence of sea surface dynamics over the interpopulation exchange dynamics and the role of protected and nonprotected coral reef in the Colombian Caribbean. Thus, the Colombian Caribbean population of O. faveolata could be relevant to the conservation of genetic diversity on a larger scale.

     

Historical and contemporary habitat use of sperm whales around the Galápagos Archipelago: Implications for conservation

1. Sperm whales have occupied the waters off the Galápagos Islands, Ecuador, for at least the past 200 years. During the 19^th century, they were the target of intensive whaling that severely depleted the population. In recent times, after commercial whaling ended, sperm whales in the region remain vulnerable to multiple threats, especially potential entanglement in fishing gear, which may hinder their ability to recover from the whaling era.
2. As a highly mobile, long-lived species, long-term analysis of the habitat use of sperm whales is necessary to establish effective conservation and management strategies. Here, contemporary (1985–2014) and historical (1830–1850) sperm whale habitat use off the Galápagos Islands was analysed and contrasted to the extent of the Galápagos Marine Reserve (GMR). Contemporary habitat use and its variability over time were modelled as a function of geographic, oceanographic, and topographic variables using generalized additive models.
3. The fine-scale habitat (<50 km) used by sperm whales was associated with topographic (i.e. depth and slope) and oceanographic characteristics (i.e. relative sea surface temperature and standard deviation of sea surface temperature), but these preferences varied over time.
4. While historical and contemporary data indicate that sperm whale habitat primarily occurred within the boundaries of the GMR, in recent years, whales were found up to 30.1% of the time outside the GMR, potentially overlapping with commercial fisheries operating in the area.
5. The dynamic nature of the relationship of this nomadic species with its habitat highlights the need of large-scale conservation efforts across the Eastern Tropical Pacific region, including the wide-scale enforcement of regulations requiring the use of Automatic Identification System in fishing vessels, the promotion of on-board fisheries observer programmes, the development of adaptive management strategies, and international collaboration to identify and mitigate threats.

     

Science and conservation of Amazonian crocodilians: a historical review

1. Crocodilians represent one of the oldest extant vertebrate lineages. They have co-existed with humans throughout the Amazon basin for thousands of years, often having a strong cultural and economic influence on people's lives. Shifts in the socio-economic and political reality of the Amazon basin during the last century have led crocodilian populations to face large variations in their numbers according to different levels of exploitation and strategies for their conservation.
2. This article reviews the scientific knowledge obtained between 1945 and 2019 on the biology, conservation and management for the four Amazonian crocodilian (caiman) species (Caiman crocodilus, Melanosuchus niger, Paleosuchus palpebrosus and Paleosuchus trigonatus). It provides a general overview on past and current population status and research efforts involving caimans in the Amazon basin and discusses perspectives for the future.
3. The most significant studies on the ecology, genetics and management strategies are examined in more detail and this information is contextualized to provide an overview of the most relevant findings that might explain caiman population trends over the last 75 years.
4. Systems for sustainable management in the Amazon basin have been discussed for the past 20 years, but remain rarely applicable. It is necessary to develop new ways to maintain healthy caiman populations through innovative management programmes. Sustainable harvesting of wildlife has been shown to promote conservation targets, especially those initiatives based on community co-management. In this article, we propose some general guidelines for future management schemes, in the expectation that the information provided by the scientific community will be considered fully without political agendas determining the priorities.

     

Promoting connectivity between priority freshwater sites for conservation in intermittent hydrological systems

1. Systematic conservation planning in freshwater ecosystems faces multiple challenges because of the dynamic nature of rivers and their multiple dimensions of connectivity. In intermittent hydrological systems connectivity is functional when water is available, allowing the exchange of aquatic individuals between isolated freshwater ecosystems. Integrating these isolated systems in their hydrological context is essential when identifying priority areas for conservation, in order to try to minimize the propagation of threats into target water bodies (management units) from the surrounding landscape.
2. Here, the use of a systematic planning approach is demonstrated to identify a set of priority management units to preserve freshwater biodiversity in an arid system of fragmented water bodies immersed in a landscape subject to a range of impacts.
3. Twenty-six water-dependent taxa from 59 mountain rock pools (gueltas) of three southern Mauritanian mountains were used as a case study. A conservation planning tool (marxan ) was used to find priority conservation areas to integrate intermittent hydrological systems in their hydrological context, promote connectivity, and minimize the downstream propagation of threats. Three types of connectivity were analysed: (i) no connectivity, (ii) connectivity between gueltas, and (iii) connectivity between gueltas and sub-catchments.
4. Considering different types of longitudinal connectivity affects the number and spatial allocation of the priority gueltas selected, and the conservation status of the gueltas and their upstream areas. Incorporating connections between gueltas and upstream locations in the modelling resulted in the selection of gueltas in areas with a low human footprint and in the increased connectivity of the solutions.
5. The results obtained revealed important locations for local biodiversity conservation, and the method presented can be used when assessing the propagation of potential waterborne threats into isolated management units. The framework developed allows connectivity to be addressed in conservation planning. It can be replicated in regions with similar isolated habitats that connect through intermittent hydrological systems and can also be applied to lateral and vertical hydrological connectivity.

     

Harnessing the potential for otolith microchemistry to foster the conservation of Amazonian fishes

1. Freshwater environments host roughly half of the world’s fish diversity, much of which is concentrated in large, tropical river systems such as the Amazon. Fishes are critical to ecosystem functioning in the Amazon River basin but face increasing human threats. The basic biology of these species, and particularly migratory behaviour, remains poorly studied, in part owing to the difficulty associated with conducting tagging studies in remote tropical regions.
2. Otolith microchemistry can circumvent logistical issues and is an increasingly important tool for studying fish life histories. However, this approach is still new in the Amazon, and its potential and limitations to inform fish conservation strategies remain unclear.
3. Here, otolith microchemistry studies in the Amazon are reviewed, highlighting current possibilities, and several key factors that limit its use as a conservation tool in the Amazon are discussed. These include the dearth of spatiotemporal elemental data, poor understanding of environment–fish–otolith pathways, and insufficient funding, facilities, and equipment.
4. A research initiative is proposed to harness the potential of this technique to support conservation in the Amazon. Key aspects of the proposal include recommendations for internal and external funding, which are critical to acquiring and maintaining technical staff, cutting-edge equipment, and facilities, as well as fostering regular scientific meetings and working groups. Meetings can facilitate a systematic approach to investigating environment–otolith pathways, broadening the chemical baseline for most Amazonian tributaries, and exploring potential valuable elements.
5. These outcomes are urgently needed to conserve biodiversity and ecosystem functioning in the Amazon, especially given threats such as widespread hydroelectric damming. The initiative proposed here could make otolith microchemistry an important, cost-effective tool to inform and foster conservation in the Amazon, and act as a template for other imperilled tropical river basins, such as the Mekong and the Congo.