The sounds of silence: regime shifts impoverish marine soundscapes

Context

Regime shifts are well known for driving penetrating ecological change, yet we do not recognise the consequences of these shifts much beyond species diversity and productivity. Sound represents a multidimensional space that carries decision-making information needed for some dispersing species to locate resources and evaluate their quantity and quality.

Objectives

Here we assessed the effect of regime shifts on marine soundscapes, which we propose has the potential function of strengthening the positive or negative feedbacks that mediate ecosystem shifts.

Methods

We tested whether biologically relevant cues are altered by regime shifts in kelp forests and seagrass systems and how specific such shifted soundscapes are to the type of driver; i.e. local pollution (eutrophication) vs. global change (ocean acidification).

Results

Here, we not only provide the first evidence for regime-shifted soundscapes, but also reveal that the modified cues of shifted ecosystems are similar regardless of spatial scale and type of environmental driver. Importantly, biological sounds can act as functional cues for orientation by dispersing larvae, and observed shifts in soundscape loudness may alter this function.

Conclusions

These results open the question as to whether shifted soundscapes provide a functional role in mediating the positive or negative feedbacks that govern the arrival of species associated with driving change or stasis in ecosystem state.

     

Growth,enzymatic glutathione peroxidase activity and biochemical status of juvenile barramundi (<Emphasis Type="Italic">Lates calcarifer</Emphasis>) fed dietary fermented soybean meal and organic selenium

Solvent-extracted soybean meal (SBM) was fermented using baker’s yeast Saccharomyces cerevisae at 30 °C for 5 days. Four isonitrogenous and isocaloric diets containing 75% SBM protein, either fermented or non-fermented (SBM and FSBM), and supplemented or not with organic Se (OS) (SBM_OS and FSBM_OS), were fed to triplicate groups of juvenile barramundi (Lates calcarifer) (initial weight of 5 g) for 75 days. A fishmeal (FM)-based diet formulated for juvenile barramundi was used as a reference diet. The growth of fish was significantly affected by either the interaction of SBM type or by the OS level. In fish fed diets supplemented with OS (SBM_OS and FSBM_OS), final weight (FW), specific growth rate (SGR) and weight gain (WG) were higher in fish fed the fermented SBM (FSBM_OS) than in those fed the non-fermented SBM (SBM_OS). The apparent digestibility coefficient (ADC) of protein was higher in the fish fed the fermented SBM, either supplemented or unsupplemented with OS. However, there were no significant differences in the ADC of dry matter (DM) and lipids among the tested diets and in comparison to the reference diet. The haematocrit and leucocrit of fish fed the FSBM_OS diet were lower than those of fish fed the FM diet. Furthermore, glutathione peroxidase (GPx) activity was significantly influenced by OS supplementation in the experimental diets; GPx activity was greater in the fish fed diets supplemented with OS. Creatinine kinase (CK) of all groups of fish was higher than the CK of those fed the reference diet. These results suggest that with a proper nutritional level, OS supplementation may act as an important factor in enzymatic GPx activity and in the haematology and blood biochemistry status of juvenile barramundi fed fermented SBM-based diets, encouraging improvement of the overall growth performance.     

Designing a Score-Based Method for the Evaluation of the Nutritional Quality of the Gluten-Free Bakery Products and their Gluten-Containing Counterparts

Gluten-free (GF) products are consumed both by individuals with celiac disease and by an increasing number of people with no specific medical needs. Although the technological quality of GF products has been recently improved, their nutritional quality is still scarcely addressed. Moreover, the few published studies report conflicting results, mostly because the information from product nutrition facts is the only considered factor. The aim of the present study was to develop a score-based method for the nutritional evaluation of 134 packaged Italian GF bakery products and to compare it with that of 162 matched gluten-containing (GC) food items. The score included the information from the nutrition facts and the presence/absence of some nutritionally relevant components in the ingredients list. Results indicated an overall low nutritional quality of the considered GF bakery products. Additionally, with the sole exception of GF bread substitutes, there was no difference in nutritional quality between GF and equivalent GC bakery products. Future research and development of GF bakery products may take advantage of this scoring method, as it may represent an easy approach to evaluate their nutritional quality. The present findings do not justify the consumption of packaged GF bakery products by people without any specific medical needs.     

Pathogenicity,Morpho-Species and Mating Types of <Emphasis Type="Italic">Alternaria</Emphasis> spp. causing Alternaria blight in <Emphasis Type="Italic">Pistacia</Emphasis> spp. in Turkey

Alternaria genus includes many plant pathogens on numerous hosts, causing leaf spots, rots and blights. Alternaria blight has been observed as one of the important fungal diseases of pistachio (Pistacia vera L.) as well as its wild relatives (P. terebinthus, P. lentiscus, P. khinjuk, P. atlantica, P. mutica) in Turkey. Alternaria species were sampled from Pistacia spp. hosts from different geographic regions in Turkey during field trips in late spring to early fall of 2013. Alternaria blight symptoms were observed mainly on fruits and rarely on leaves. Four hundred and twenty two of the isolates were morphologically defined as A. alternata, A. tenuissima, A. arborescens and also intermediate morpho-species between A. alternata/A. arborescens. Pathogenicity of the isolates was confirmed with host inoculations on detached fruits. Mating types of 270 isolates of Alternaria spp. from the collection were identified using a PCR-based mating type assay that amplifies either a MAT1-1 or a MAT1-2 fragment from the mating locus. Although a strongly clonal population structure was expected due to the putative asexual reproduction of these fungi, both idiomorphs were detected at equal frequencies at several different spatial scales. The distribution of mating types within each geographic region, within host species as well as in overall collection was not significantly different from 1:1. Amplified fragments of partial idiomorph sequences were obtained for representative isolates. Parsimony trees were depicted based on sequence data of mating type genes for these representative isolates as well as some other Alternaria species obtained by Genebank. Several point mutations presented a few clusters which are supported by high bootsrapped values. The Alternaria blight disease agents both from cultivated and wild hosts were pathogenic on pistachio which may cause difficulties to control the disease because of extensity of pathogen sources. Besides, equal mating type distribution of the pathogen at both geographic and host species levels suggests a potential for sexual reproduction of Alternaria spp. in Turkey.     

Loquat as a crop model for successful deficit irrigation

During three consecutive seasons, two different deficit irrigation strategies were compared with control fully irrigated trees regarding their capacity to induce early bloom and harvest in “Algerie” loquat. The first strategy, a continuous deficit irrigation strategy, consisted in a uniform reduction of 20% water needs through the entire season; the second strategy, a regulated deficit irrigation approach, while accounting for the same global reduction of 20% loquat water needs, concentrated water shortages after harvest from mid-May through the end of August. Regulated deficit irrigation resulted more successful. Postharvest regulated deficit irrigation advanced full bloom 10–20 days depending on the season. Such enhancement led to more precocious and valuable yield, with an average increase of fruit value of 0.21 € kg⁻¹. The effects of continuous deficit irrigation were less noticeable and average fruit value was increased 0.08 € kg⁻¹. Yield and fruit quality were not affected for the different deficit irrigation strategies. Water savings established around 1450 m³ ha⁻¹ year⁻¹. Deficit irrigation rose water use efficiency up to more than a 40%.     

Recreational fishery as a conservation tool for endemic Dolly Varden <Emphasis Type="Italic">Salvelinus malma miyabei</Emphasis> in Lake Shikaribetsu,Japan

Recreational angling is a popular leisure activity globally and can be a threat or useful conservation tool depending on the management strategy. Miyabe charr Salvelinus malma miyabei is an endemic fish that inhabits Lake Shikaribetsu, and a management program was established to harmonise recreational fishery and conservation. To examine the suitability of this program, population assessment was conducted with the cooperation of anglers. The population size in 2014 as assessed by tag-and-release angling was estimated to be 105,300 [95% confidence interval (CI) 37,300–178,600], much higher than the reported estimate in 1995. Further, angling mortality was estimated to be quite low. Moreover, no decreasing population trend was detected on analysing 8 years of anglers’ catch data. Consequently, angling has facilitated stock assessments of Miyabe charr under the current program. This case is a good example of recreational angling acting as a conservation tool under appropriate management.     

Fasciation in <Emphasis Type="Italic">Crassula argentea</Emphasis>: molecular identification of phytoplasmas and associated antioxidative capacity

The present study reports on phytoplasma induced fasciation in Crassula argintea (Crassulaceae). DNA was extracted from symptomless and fasciated tissues and amplified by nested PCR using universal primers P1/P7 followed by R16F2n/R16R2 produced amplicons of 1.2 Kb. The nucleotide sequence analyses of the amplicons indicated that fasciated plants were infected by phytoplasma. Phylogenetic analysis placed the Crassula fasciation phytoplasmas in 16SrII-D group. Histochemical staining for reactive oxygen species indicated that phytoplasma infected (PI) tissues possess significantly higher levels of hydrogen peroxide (H₂O₂) rather than superoxide (O₂ ^·-) as compared with symptomless tissues. PI tissues were also associated with a significant increase in antioxidant enzyme activities (catalase, peroxidase, polyphenol oxidase, and glutathione reductase) and electrolyte leakage as compared with symptomless tissues.     

Pathogens of bark beetles (Coleoptera: Curculionidae) in Bulgarian forests

The occurrence and prevalence of bark beetle pathogens in forest stands in Bulgaria were investigated in 944 specimens belonging to 21 bark beetle species. Protozoa, microsporidia, fungi and nematodes occurred in 19 of all investigated species. The infections were found in the gut (nematodes, gregarines, microsporidia), gonads (microsporidia) and hemolymph (nematodes) of the infected insects. Protozoan species (Gregarina typographi, Gregarina spp.) were detected in eight bark beetle species. Morphometric data about G. typographi and Gregarina spp. are presented. The prevalence of the gregarines varied between 1.4% and 64.2%. Microsporidia of the genera Nosema and Chytridiopsis were revealed in three bark beetle species. The prevalence of microsporidia ranged between 1.5% and 11.8%. This is the first report of a microsporidium in Taphrorychus villifrons and of gregarines in T. villifrons, Pityogenes bistridentatus, P. conjunctus, and Orthotomicus erosus. The fungus Beauveria bassiana was found in 3.4% of Hylurgops palliatus specimens. Nematodes (in gut and haemolymph) were revealed in 19 bark beetle species and their prevalence varied between 10% and 98.5%.     

Content of Nutrient and Antinutrient in Edible Flowers of Wild Plants in Mexico

Nutrient and antinutritional/toxic factors present in some edible flowers consumed in Mexico were determined. The edible flowers were: Agave salmiana, Aloe vera, Arbutus xalapensis, Cucurbita pepo (cultivated), Erythrina americana, Erythrina caribaea, Euphorbia radians benth and Yucca filifera. The nutrient content in the flowers studied is similar to that of the edible leaves and flowers studied mainly in Africa. The moisture content of the flowers varied from 860 to 932 g kg⁻¹. Crude protein (CP) was between 113 to 275 g kg⁻¹ DM, crude fiber, 104 to 177 g kg⁻¹ DM and the nitrogen free extract, between 425 to 667 g kg⁻¹ DM. The highest chemical score (CS) was found in E. americana and A. salmiana; in five samples the limiting amino acid was lysine, and in three of them it was tryptophan. Trypsin inhibitors and hemaglutinnins had a very low concentration. Alkaloids were present in both the Erythrina species and the saponins in A. salmiana and Y. filifera. Cyanogenic glucosides were not found in the studied flowers. The traditional process of preparing these specific flowers before consumption is by cooking them and discarding the broth; in this way the toxic substances are diminished or eliminated. These edible flowers from wild plants consumed in local areas of the country play an important role in the diet of the people at least during the short time of the season where they are blooming.