Functional connectivity from a reef fish perspective: behavioral tactics for moving in a fragmented landscape

Functional connectivity, the degree to which the landscape facilitates or impedes movement, depends on how animals perceive costs and benefits associated with habitat features and integrate them into a movement path. There have been few studies on functional connectivity in marine organisms, despite its importance for the effectiveness of Marine Protected Areas. In this study, we asked how open sand and conspecific distribution affected functional connectivity of longfin damselfish (Stegastes diencaeus) on fringing reefs in Barbados. We translocated 102 individuals to sites varying in sand gap width and in configuration: Continuous (solid reef between release site and territory); Detour (sand along the direct path between release site and territory, but an alternative, continuous solid U-shaped reef path); and Patch (sand between release site and territory, but an alternative stepping stone path). We visually tracked and mapped every homing path. We found no evidence of a barrier to movement in the Continuous configuration, but sand was a partial barrier in Detour and Patch configurations. The probability of crossing the sand gap dropped below 50% when its width was > 1.85 m in Detour and > 3.90 m in Patch configuration. Damselfish avoiding large gaps took detours that approximated the route maximizing travel over reef, but they crossed more short sand gaps and fewer conspecific territories, suggesting avoidance of agonistic interactions. This study quantifies for the first time the size and steepness of a barrier to movement in a marine organism, and it provides evidence for effects of both landscape configuration and conspecific distribution on functional connectivity.     

Physiological and behavioral responses of temperate seahorses (Hippocampus guttulatus) to environmental warming

The aim of the present study was to evaluate, for the first time, the effect of environmental warming on the metabolic and behavioral ecology of a temperate seahorse, Hippocampus guttulatus. More specifically, we compared routine metabolic rates, thermal sensitivity, ventilation rates, food intake, and behavioral patterns at average spring temperature (18 °C), average summer temperature (26 °C), temperatures that they endure during summer heat wave events (28 °C), and in a near-future warming scenario (+2; 30 °C) in Sado estuary, Portugal. Both newborn juveniles and adults showed significant increases in metabolic rates with rising temperatures. However, newborns were more impacted by future warming via metabolic depression (i.e., heat-induced hipometabolism). In adult stages, ventilation rates also increased significantly with environmental warming, but food intake remained unchanged. Moreover, the frequency of swimming, foraging, swinging, and inactivity did not significantly change between the different thermal scenarios. Thus, we provide evidence that, while adult seahorses show great resilience to heat stress and are not expected to go through any physiological impairment and behavioral change with the projected near-future warming, the early stages display greater thermal sensitivity and may face greater metabolic challenges with potential cascading consequences for their growth and survival.     

Identification of the sex pheromone of Conogethes pluto: a pest of Alpinia

In recent years, Conogethes pluto (Lepidoptera: Crambidae) has become a major pest of Alpinia and other ornamental gingers in the Northern Territory and Queensland, Australia. This pest damages the flowers and bores into the stems, causing substantial losses to production. Currently, no synthetic sex pheromone is available to monitor or control this pest. This work aims at the identification of the sex pheromone of this pest. Analysis of the sex pheromone gland of female C. pluto by gas chromatography/electroantennogram detector revealed the presence of seven candidate pheromone compounds that elicited electroantennogram responses. Using gas chromatography/mass spectrometry analysis and micro-derivatization reactions, six compounds were identified as (E)-10-hexadecenal, as the main pheromone compound, (Z)-10-hexadecenal, hexadecanal, (E)-10-hexadecen-1-ol, (10E,12E)-hexadeca-10,12-dienal and (3Z,6Z,9Z)-tricosa-3,6,9-triene as minor pheromone compounds. In two-field trapping experiments, C. pluto responded to the six-component blend, and three of six compounds, i.e., (E)-10-hexadecenal, (3Z,6Z,9Z)-tricosa-3,6,9-triene, and (10E,12E)-hexadeca-10,12-dienal were shown to be necessary for attraction. In a subsequent experiment testing various doses (i.e., 0.01, 0.1, and 1 mg) of the six-component blend, the largest number of males was captured in traps baited with a lure loading of 1 mg. The availability of the sex pheromone of C. pluto will enable monitoring and provides the basis for additional control options for this pest.     

Evaluation of the effect of antimicrobials in marine cultures,using the copepod Acartia tonsa as a bioindicator

Cultures of the copepod Acartia tonsa are used both in aquaculture and ecotoxicology studies. However, the cultivation of these crustaceans at high densities results in the proliferation of microorganisms that can affect the organisms of interest, leading to illness or death. Antimicrobials inhibit microbial growth and may favour the cultivated species, aiding the development of ecological studies. This study investigated the potential of antimicrobials (antibiotic + antifungal) to inhibit bacteria and fungi when applied to marine zooplankton cultures, using the copepod A. tonsa as a bioindicator of acute toxicity. Treatment with 0.025?g?L^?1 of penicillin G potassium + 0.08?g?L^?1 of streptomycin sulphate + 0.04?g?L^?1 of neomycin sulphate + 0.005?g?L^?1 of nystatin resulted in 95% bacterial inhibition (after 12?h of exposure); however, after this time, the inhibitory effect was lost. The antimicrobial combination tested in this study prevented colonisation by fungi until 168?h after exposure, without causing acute toxicity to A. tonsa. Thus, it has potential for use in marine cultures of less sensitive organisms.     

Interactions between macroparasites and microparasites drive infection patterns in free-ranging African buffalo

Epidemiological studies typically focus on single-parasite systems, although most hosts harbor multiple parasite species; thus, the potential impacts of co-infection on disease dynamics are only beginning to be recognized. Interactions between macroparasites, such as gastrointestinal nematodes, and microparasites causing diseases like TB, AIDS, and malaria are particularly interesting because co-infection may favor transmission and progression of these important diseases. Here we present evidence for strong interactions between gastrointestinal worms and bovine tuberculosis (TB) in free-ranging African buffalo (Syncerus caffer). TB and worms are negatively associated at the population, among-herd, and within-herd scales, and this association is not solely the result of demographic heterogeneities in infection. Combining data from 1362 buffalo with simple mechanistic models, we find that both accelerated mortality of co-infected individuals and TB transmission heterogeneity caused by trade-offs in immunity to the two types of parasites likely contribute to observed infection patterns. This study is one of the first to examine the relevance of within-host immunological trade-offs for understanding parasite distribution patterns in natural populations.     

Changes in Tundra Pond Limnology: Re-sampling Alaskan Ponds After 40 Years

The arctic tundra ponds at the International Biological Program (IBP) site in Barrow, AK, were studied extensively in the 1970s; however, very little aquatic research has been conducted there for over three decades. Due to the rapid climate changes already occurring in northern Alaska, identifying any changes in the ponds’ structure and function over the past 30–40 years can help identify any potential climate-related impacts. Current research on the IBP ponds has revealed significant changes in the physical, chemical, and biological characteristics of these ponds over time. These changes include increased water temperatures, increased water column nutrient concentrations, the presence of at least one new chironomid species, and increased macrophyte cover. However, we have also observed significant annual variation in many measured variables and caution that this variation must be taken into account when attempting to make statements about longer-term change. The Barrow IBP tundra ponds represent one of the very few locations in the Arctic where long-term data are available on freshwater ecosystem structure and function. Continued monitoring and protection of these invaluable sites is required to help understand the implications of climate change on freshwater ecosystems in the Arctic.     

Thermoplasticization of High Amylose Starch by Chemical Modification Using Reactive Extrusion

Modified thermoplastic high amylose starch (MTPS) was synthesized by reactive extrusion in the presence of maleic anhydride (MA) as an esterification agent in a twin-screw extruder. The objective of this work was the preparation of reactive thermoplastic starch in the presence of glycerol and with different amounts of maleic anhydride (MA) and free-radical initiator, in order to improve processability and reactivity. The concentration of MA added varied from 2 to 6 wt% (of starch + glycerol), and the free-radical initiator, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, also called Luperox 101, varied from 0.1 to 0.5 wt% (of starch + glycerol). Characterization of maleated thermoplastic starch was performed using dynamic light scattering and thermal analysis. Further, proof of chemically modified extrudate was determined by Fourier transform infrared spectroscopy and by soxhlet extraction with acetone. The modified high amylose corn starch (20 or 30% glycerol) could be pelletized and gave pellets that were more transparent than thermoplastic starches not modified with maleic anhydride. There was negligible change in hydrodynamic radius as the percentage of maleic anhydride increased. However, as the percentage of Luperox 101 increased, the hydrodynamic radius decreased. It could be inferred that the molecular weight decreased as the percentage of free-radical initiator increased. Using the maximum temperature in the extrusion process of 165 °C instead of 135 °C caused a decrease in the hydrodynamic radius, due to the high influence of the temperature profile on the molecular weight of the thermoplastic starch. The MTPS samples presented higher melting temperatures compared to TPS samples. The soxhlet studies indicated that the plasticizer, glycerol, was chemically linked to the starch. Using the maximum temperature of 165 °C versus 135 °C in the extrusion temperature profile resulted in more interaction between glycerol and starch.     

How Perceived Exposure to Environmental Harm Influences Environmental Behavior in Urban China

Rapid environmental degradation in China makes understanding how perceived exposure to environmental harm influences environmental attitudes and participation in pro-environmental behaviors among the Chinese people crucial. We used a nation-wide survey dataset in urban China to test two hypotheses: experiencing environmental harm directly affects environmental behavior; environmental attitudes mediate the relationship between experiencing environmental harm and environmental behavior. We found respondents who experienced environmental harm had more pro-environmental attitudes. Experiencing environmental harm positively influenced pro-environmental behavior both directly and indirectly through the mediation of pro-environmental attitudes. Among the pro-environmental behaviors, environmental litigation was most strongly related with exposure to environmental harm. Our results suggest that more participation in pro-environmental behaviors may be expected as rapid economic development increases public exposure to environmental harm in urban China.     

Biomarker responses as indication of contaminant effects in Oreochromis niloticus

The current study investigated oxidative stress parameters (enzymes activities, metallothionein content and lipid peroxidation) in freshwater fish, Oreochromis niloticus, tilapia exposure to Monjolinho River (in 4 months of year: January, April, July and November). One critical site in Monjolinho River (site B) was assessed in comparison to a reference site (site A). Water pH and oxygen concentration was lower than that recommended by CONAMA (Brazilian National Environmental Committee), resolution 357/2005 for protection of aquatic communities, and ammonium and the metals Cu, Zn, Mn and Fe (on all months) concentrations were higher than the maximum concentration recommended. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were significantly decreased in liver and muscle in tilapia from Monjolinho River, throughout the year, in relation to reference except in gills that SOD activity increased. Glutathione S-transferase (GST) activity was significantly increased in liver of the tilapia from Monjolinho River in all sites, in relation to reference except in gills that GST activity increased in July and decreased in November, suggesting that GST activity could be induced to neutralize the pollutants toxicity. On the other hand, GST activity was significantly decreased in white muscle indicating a toxic effect of pollutants, resulting in a decreased ability of tilapia to perform defense reactions associated to GSTs. The decrease of catalase (CAT) activity in gills of the O. niloticus together with the increase of SOD activity, could explain the increased lipid peroxidation (LPO) level in this organ. Metallothionein levels in liver and gills were significantly high in all sites. Results indicate that the exposure to metals caused severe damage to tissues; despite the consensually assumed antioxidant induction as a sign of exposure to contaminants the effects seem in part to be mediated by suppression of antioxidant system with SOD, CAT and GPx as potential candidates for tissues toxicity biomarkers of pollutants.