Expansion and fragment settlement of the non-native seagrass Halophila stipulacea in a Caribbean bay

The non-native seagrass species Halophila stipulacea has spread throughout the Eastern Caribbean since 2002, and could potentially impact the functioning of local seagrass ecosystems. Important characteristics for invasiveness, such as dispersal, recruitment and expansion of H. stipulacea at a local scale, are unknown. We assessed H. stipulacea expansion rates within Lac Bay, Bonaire, Dutch Caribbean (7?km²), since its establishment in 2010 and tested the settlement potential of uprooted vegetative fragments of H. stipulacea. Using 49 fixed locations, we observed that between 2011 and 2015 the occurrence of H. stipulacea in the bay increased significantly from 6% to 20% while native Thalassia testudinum occurrence decreased significantly from 53% to 33%. Free-floating H. stipulacea fragments that were collected and tethered above the sediment rooted within 10 days with a settlement success rate of 100%. The growth of settled fragments was on average 0.91 shoots d^?1. The ongoing shift from native T. testudinum to introduced H. stipulacea dominated meadows may have important consequences for multiple Caribbean seagrass ecosystem functions. Given the large difference in size between the two seagrass species, functions such as coastal protection, habitat structure, food availability, and the stability and resilience of these systems can be altered. The next steps towards modelling future expansion of H. stipulacea throughout the Caribbean and beyond should include the assessment of fragment viability and dispersal distance, and the impacts of natural and anthropogenic disturbance on vegetative fragment density, dispersion and settlement by this species.     

Spatiotemporal effects of Hurricane Ivan on an endemic epiphytic orchid: 10 years of follow-up

ABSTRACT

Background: Hurricanes have a strong influence on the ecological dynamics and structure of tropical forests. Orchid populations are especially vulnerable to these perturbations due to their canopy exposure and lack of underground storage organs and seed banks.

Aims: We evaluated the effects of Hurricane Ivan on the population of the endemic epiphytic orchid Encyclia bocourtii to propose a management strategy.

Methods: Using a pre- and post-hurricane dataset (2003–2013), we assessed the population asymptotic and transient dynamics. We also identified the individual size-stages that maximise population inertia and E. bocourtii’s spatial arrangement relative to phorophytes and other epiphytes.

Results: Hurricane Ivan severely affected the survival and growth of individuals of E. bocourtii, and caused an immediate decline of the population growth rate from λ = 1.05 to λ = 0.32, which was buffered by a population reactivity of ρ₁ = 1.42. Our stochastic model predicted an annual population decrease of 14%. We found an aggregated spatial pattern between E. bocourtii and its host trees, and a random pattern relative to other epiphytes.

Conclusion: Our findings suggest that E. bocourtii is not safe from local extinction. We propose the propagation and reintroduction of reproductive specimens, the relocation of surviving individuals, and the establishment of new plantations of phorophytes.     

A Bryophyte flora of Kent. I

Abstract

Gender expression and sporophyte frequency of Frullania tamarisci were compared between epiphytic woodland and exposed coastal colonies in an Atlantic region of western Britain. Corticolous colonies exhibited very high sporophyte frequency in mixed-sex colonies. Samples from well-grown epiphytic patches commonly had intimate mixtures of highly fertile female and male shoot networks, and fertilisation reduced gynoecia number. In marked contrast, colonies in exposed coastal habitats were found to be sub-fertile or non sex-expressing and sporophytes were rare. There was a distinct female bias among colonies on the coast where spatial segregation of the sexes and male scarcity appear to limit sporophyte frequency. It is suggested that the close association of males and sporophytic females in epiphytic colonies may be influenced by within-colony sporophyte frequency.     

Canopy cover and understory composition determine abundance of Vaccinium myrtillus L., a key plant for capercaillie (Tetrao urogallus), in subalpine forests in the Pyrenees

Background: The dwarf shrub Vaccinium myrtillus – with high cover, height, and fruit production – benefits capercaillie (Tetrao urogallus).

Aims: Our aim was to quantify landscape (e.g. elevation, geographic location, and precipitation), site (e.g. overstorey cover and stoniness) and very fine scale factors (e.g. spatial associations in the understorey) that affect cover, height, and fruit production of V. myrtillus in subalpine forests in thePyrenees, with understorey usually dominated by Rhododendron ferrugineum.

Methods: We sampled 155 plots (0.5 m × 5 m) in six sites. For each plot, in the understorey layer, we assessed species cover, height for R. ferrugineum and V. myrtillus, number of total fruits in V. myrtillus, and spatial associations among V. myrtillus and the remaining cover types.

Results: Overstorey cover negatively influenced V. myrtillus cover, its height, and particularly, the number of fruits, which was also negatively influenced by R. ferrugineum cover. Associations between R. ferrugineum and V. myrtillus were site dependent, while V. myrtillus showed mostly positive associations with grasses and mosses.

Conclusions: Reducing overstorey and R. ferrugineum cover has the strongest positive effect on increasing V. myrtillus fruit production, but with additional positive effects on V. myrtillus cover and height. Increases in grass and moss coverage could favour V. myrtillus.     

Tree and stand level variables influencing diversity of lichens on temperate broad-leaved trees in boreo-nemoral floodplain forests

Tree and stand level variables affecting the species richness, cover and composition of epiphytic lichens on temperate broad-leaved trees (Fraxinus excelsior, Quercus robur, Tilia cordata, Ulmus glabra, and U. laevis) were analysed in floodplain forest stands in Estonia. The effect of tree species, substrate characteristics, and stand and regional variables were tested by partial canonical correspondence analysis (pCCA) and by general linear mixed models (GLMM). The most pronounced factors affecting the species richness, cover and composition of epiphytic lichens are acidity of tree bark, bryophyte cover and circumference of tree stems. Stand level characteristics have less effects on the species richness of epiphytic lichens, however, lichen cover and composition was influenced by stand age and light availability. The boreo-nemoral floodplain forests represent valuable habitats for epiphytic lichens. As substrate-related factors influence the species diversity of lichens on temperate broad-leaved trees differently, it is important to consider the effect of each tree species in biodiversity and conservation studies of lichens. Nomenclature Randlane et al. (2007) for lichens; Leht (2007) for vascular plants.     

Chemical Analysis of Selected Seaweeds and Seagrass from the Adriatic Coast of Montenegro

Three seaweeds (Halimeda tuna, Codium bursa and Cystoseira barbata) and one seagrass (Cymodocea nodosa) were collected from the Coast of Montenegro, Gulf of Boka Kotorska and their chemical analysis was performed. In seagrass C. nodosa, three phenolic compounds were identified (diosmetin 7‐sulfate, caftaric and coutaric acid). The content of β‐glucan, fatty acids, sterols and micro‐ and macro‐elements were investigated among all samples. The highest content of β‐glucan was detected in C. nodosa seagrass (13.04±0.42 g/100 g). The highest polyunsaturated fatty acids (PUFAs) level was reported in C. barbata, the brown alga (7.157 mg/g), which also had the significant sterol content (fucosterol, 21.76±0.1 μg/g). Green algae, C. bursa and H. tuna, showed the highest level of sterols (β‐sitosterol, 95.21±0.16 μg/g and 73.90±0.08 μg/g, respectively). H. tuna had the highest content of calcium (Ca) in amount of 55125 μg/g. In C. bursa, C. barbata and C. nodosa, the Na/K ratio was low (0.43, 0.46 and 0.69, respectively).     

The distribution and expansion of the invasive seagrass Halophila stipulacea in Dominica, West Indies, with a preliminary report from St. Lucia

The seagrass Halophila stipulacea Forsskål, native to the Red Sea, is an invasive species in the Mediterranean that was recently observed offshore Grenada, in the Caribbean. Here, we document the presence of this seagrass in Dominica and St. Lucia, demonstrating it has spread across part of the eastern Caribbean. H. stipulacea in Dominica was present in seven locations along the west coast covering more than 22.9 ha of the benthos, at depths from 2 to 18 m. Populations were concentrated in or adjacent to bays frequented by recreational or commercial boats, likely vectors for the introduction. Morphological features varied from bed to bed, with depth being the predominant driving factor. H. stipulacea had a rapid mean lateral bed expansion rate of 0.5 cm d⁻¹, with a maximum rate of >6 cm d⁻¹. H. stipulacea patches often occurred exclusive of the otherwise dominant seagrasses of the Caribbean. The potential for the expansion of H. stipulacea, combined with its tolerance for a wide spectrum of environmental conditions, positions it as a potential threat to local and regional biodiversity.     

Impact of different shade coffee management scenarios,on a population of Oncidium poikilostalix (Orchidaceae), in Soconusco,Chiapas, Mexico

Background: Understanding the effect of perturbation, be it natural or anthropogenic, on the demography and dynamics of the plant populations can help conservation management planning.

Aims: We assessed the impacts of management of a shade coffee plantation on a population of Oncidium poikilostalix (Orchidaceae).

Methods: We studied in a coffee (Coffea arabica) agroecosystem the impact of the current traditional management [T] and two hypothetical epiphyte control management scenarios (intense ‘desmusgue’ [ID] and moderate ‘desmusgue’ [MD]), on the only known Mexican population of O. poikilostalix. Based on 3 years of field demographics data, the population dynamics of the orchid were projected using T, ID and MD scenarios for 20 years into the future.

Results: Under the current management T, the population of O. poikilostalix was projected to grow continuously (λ = 1.102). Conversely, under management ID, the loss of individuals would lead to a sustained population decline (λ = 0.843); in the case of MD, the population would decline more slowly with the population growth rate tending towards equilibrium (λ = 0.966).

Conclusions: The changes in the management of coffee plantations that have become common throughout the south-east of Mexico represent a threat to the survival of the only population of O. poikilostalix in Mexico, and likely threaten other epiphytic species.     

Response of performance characteristics and fecal consistency to long-lasting dietary supplementation with the probiotic strain Bacillus cereus var. toyoi to sows and piglets

Abstract

As part of an interdisciplinary research project, we studied the performance response of sows and their litters to the probiotic strain Bacillus cereus var. toyoi as well as feces consistency of piglets. Gestating sows (n = 26) were randomly allotted into two groups. The probiotic B. cereus var. toyoi was administered by dietary supplementation to one group of sows and their respective litters (probiotic group) whereas the second group (control group) received no probiotic supplementation. The duration of the application was nearly 17 weeks for sows (day 90 ante partum until day 28 post partum) and six weeks for piglets (day 15–56). Piglets were weaned after 28 days. Body weight and feed consumption were recorded weekly and fecal consistency of weaned piglets was studied daily. B. cereus var. toyoi was recovered from feces of sows and piglets as well as from digesta of piglets in the probiotic group, while being absent from all samples of control animals. In addition, the probiotic was detected in piglet feces and digesta before pre-starter feed was offered, indicating a second route of uptake besides diet. Sows of the probiotic group nursed numerically more piglets and supported a higher sum of total nursing days of all piglets within each litter than control sows (p = 0.04). In turn, body weight (BW) up to day 35 was greater for control piglets (p < 0.01), while average daily gain and gain to feed ratio (G:F) in weeks six and eight postweaning was higher in the probiotic group (p < 0.05). The overall G:F of the total postweaning period was 680 g/kg and 628 g/kg in the probiotic group and control group, respectively (p = 0.009). During the trial a high prevalence of liquid feces with its maximum in the second week after weaning was observed. Probiotic supplementation led to a reduction in the incidence of liquid feces and postweaning diarrhea by 38% and 59%, respectively (p < 0.001).     

The impact of red deer on liverwort-rich oceanic heath vegetation

Background: There is concern about increasing numbers of large herbivores including red deer (Cervus elaphus), but little is known about their impact on bryophytes.

Aims: This study set out to determine the effect of different localised densities of red deer on the internationally important Northern Atlantic hepatic mat, characteristic of oceanic heath vegetation, at four locations in the Scottish Highlands where sheep have been absent for decades.

Methods: Thirty 7 m × 7 m plots were randomly located in each study area. The standing crop dung pellet group count method was used to estimate red deer density. Species richness, diversity and cover of hepatic mat liverworts were obtained from 1 m × 1 m quadrats placed at random within the sample plots. Calluna vulgaris cover, ericoid height, rock cover, gradient and altitude were also recorded.

Results: Model simplification in analysis of covariance revealed a consistent pattern of decreasing cover of hepatic mat and Calluna with increasing red deer density at all four study areas. Northern Atlantic hepatic mat cover, diversity and species richness were positively correlated with Calluna cover.

Conclusions: The data suggest that Calluna cover is reduced (through trampling and browsing) at high local densities of red deer which has had cascading effects on the Northern Atlantic hepatic mat. Alternative explanations are discussed.     

Susceptibility of three lepidopteran pests to five entomopathogenic nematodes and in vivo mass production of these nematodes

Abstract

An investigation was conducted in pots to access the susceptibility of three lepidopteran pests, namely, gram pod borer, Helicoverpa armigera, greater wax moth, Galleria mellonella, and rice moth, Corcyra cephalonica, to two recently described species, Steinernema masoodi, S. seemae, and three indigenous S. carpocapsae, S. glaseri and S. thermophilum entomopathogenic nematodes (EPN). The suitability of these lepidopterans for the in vivo mass production of the nematodes was also estimated. Among the five species of EPN, S. masoodi, S. seemae and S. carpocapsae were found most pathogenic to C. cephalonica, bringing about mortality within 24 h, followed by H. armigera (36, 38 and 48 h, respectively) and G. mellonella (30, 36 and 48 h, respectively). The other species of EPN, viz., S. glaseri and S. thermophilum was the least pathogenic, which killed the larvae of C. cephalonica in 29 and 36 h, respectively, G. mellonella in 48 h, and H. armigera in 38 and 56 h, respectively. Galleria mellonella was found the most suitable host for the mass production of infective juveniles (IJs) of S. seemae, which yielded higher IJs than S. carpocapsae. Helicoverpa armigera was the next best suitable alternate host, which produced maximum IJs in case of S. seemae followed by S. masoodi, S. carpocapsae, S. glaseri and S. thermophilum. Rice moth, Corcyra cephalonica was the least suitable host. The susceptibility of H. armigera to five tested EPN species and susceptibility of G. mellonella and C. cephalonica to S. masoodi and S. seemae are new records.     

New species of Hatschekia Poche, 1902 (Copepoda: Hatschekiidae) parasitic on marine fishes of Kuwait

Three new species of Hatschekia are described from the gill filaments of fishes taken in the Persian Gulf: H. seyi n. sp. from Heniochus acuminatus (Linnaeus), H. nodosa n. sp. from Lutjanus coccineus (Cuvier) and H. tanysoma n. sp. from L. fulviflamma (Forsskål). H. seyi differs from its congeners in having the cephalothorax longer than the trunk; H. nodosa, in having multiple nodules on the posterolateral margins of the trunk; and H. tanysoma, in having the trunk more than six times the length of cephalothorax and some pinnate setae on legs 1 and 2.     

Responses of two Mediterranean seagrasses to experimental changes in salinity

The aim of this study is to examine the effects of variations in salinity levels on growth and survival of two fast-growing Mediterranean seagrasses, Cymodocea nodosa and Zostera noltii. We also tested the capacity of C. nodosa to acclimate to a gradual increase in salinity and to discover how it responds to a sharp rise in salinity in combination with other factors, such as increases in temperature, seasonality and different plant-population origins. Several short-term (10 days) experiments were conducted under controlled conditions. For each experiment, ten marked shoots were placed in 5-l aquaria, where they were exposed to different salinity treatments (ranging from 2 to 72 psu). Growth and survival of both species were significantly affected by salinity. A significant effect between salinity and temperature on the shoot growth rate of C. nodosa was also detected, but not on shoot mortality. When C. nodosa plants were acclimated by gradually increasing the salinity level, it was observed that acclimatisation improved tolerance to salinity changes. A different response to salinity variations, depending on the origin of the plants or the season of the year, was also detected. These results indicated that Z. noltii plants tolerate conditions of hyposalinity better than C. nodosa, and that the tolerance range of C. nodosa may change depending on the temperature, the season or the population.     

Chromosome numbers of the European seagrasses

The chromosome numbers of the five European seagrasses have been determined in material from several sites along the coasts of the Atlantic Ocean, the North Sea and the Mediterranean:Zostera marina L., 2n = 12;Z. noltii Hornem., 2n = 12;Posidonia oceanica (L.)Delile, 2n = 20;Cymodocea nodosa (Ucria)Aschers., 2n = 14, 2n = 28;Halophila stipulacea (Forsk.)Aschers., 2n = 18. The difference in chromosome morphology betweenZ. marina andZ. noltii supports the division of the genus into two subgenera.     

Plant species richness in mountain forests of the Bavarian Alps

Abstract

Based on a stratified random sample of 93 vegetation plots (144 m²) from montane and subalpine climax forests in a representative section through the Bavarian Alps, spatial pattern and environmental correlates of species density of trees, vascular understorey and epigeic bryophytes were analysed. Detecting landscape scale patterns in beta- and gamma-diversity based on interpretation of rarefaction curves proved to be difficult in a sample that had been stratified by ecological criteria. In 144 m² plots tree species density (5 ± 2.0, max. 10) declined with elevation and increased with stand age (multiple R ² = 0.557). The latter effect can be attributed to the secular history of game management and browsing pressure, which has hindered the regeneration of species-rich tree stands since ca. 150 yr. Species density of the forest undergrowth reached remarkably high levels for vascular plants (42 ± 12.8, max. 69) and bryophytes (14 ± 6.0, max. 30) and strongly depended on cover of the respective layer in a unimodal pattern, suggesting to separate direct and indirect effects, mediated through the mass effect, in the subsequent construction of regression models. Multiple regression (R ² = 0.47) revealed that vascular species density is limited chiefly through low plant cover, which in turn decreases with tree cover, elevation and soil quality, and secondly by species pools that contain larger numbers of species requiring high pH and ample light. Cover and direct effects had roughly equal weight in controlling bryophyte species density (R ² = 0.57). Biomass depended on the proportion of conifers in the tree layer and on site quality, less fertile sites tending to have higher bryophyte cover. The increase of bryophyte species density with elevation was interpreted as an effect of a pool of largely boreal-subalpine species. The increase of species density with stand age suggests dispersal limitation and deserves further study.     

Potential spatial interaction of the invasive species Harmonia axyridis (Pallas) with native and endemic coccinellids

Biological invasions represent a serious menace to local species assemblages, mainly due to interspecific relationships such as competition and predation. One important invasive species worldwide is Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), which has invaded many regions of the world, threatening the native and endemic coccinellid assemblages due to negative interspecific interactions. These interactions have been widely studied at a local scale, but have been less studied at regional scales. Our aim was to estimate and analyse the potential spatial interaction associated with the co‐occurrence of H. axyridis with native and endemic species in Chile, considering bioclimatic and land cover variables. First, we created species distribution models (SDM) for H. axyridis, native and endemic coccinellids and six representative coccinellid species using maximum entropy technique. Then, we overlapped each SDM with land cover types to estimate the bioclimatic suitability within each land cover type. Finally, we identified the co‐occurrences of organisms according to the SDM and the land cover types, estimating in what land covers H. axyridis and the other coccinellids are more likely to co‐occur. Our results show that the suitable area for H. axyridis occurs from 30° to 42°S in Chile, while for native and endemic species this area is greater. The six selected species are mainly concentrated in central Chile, but differ in their potential suitable areas; Adalia angulifera Mulsant and Scymnus bicolor (Germain) have the largest range, and Mimoscymnus macula (Germain) has the most restricted one. The highest level of potential spatial interactions with H. axyridis occurs in central Chile, specifically in croplands and scrublands, and the lowest in primary native forest for all the species. Our results provide a spatially explicit baseline for coccinellid conservation and management of this invasive species.     

Mating System and Clonal Architecture: A Comparative Study in Two Marine Angiosperms

In the present study, we compared the clonal architecture between two seagrass species, the dioecious Cymodocea nodosa and the hermaphroditic, self-compatible Zostera noltii, in order to verify the hypothesis that clonal growth strategies and resulting genet architecture are associated with mating system in clonal plants. It is expected that self-incompatible species should be associated to a guerrilla growth form, because of pollen limitation due to obligate outbreeding, while the ecologically advantageous phalanx strategy can be adopted in self-compatible species. Genotypic diversity and heterozygosity were also assessed in the two species. Sampling has been conducted in mixed stands, collecting shoots of the two species at the same points of the sampling grid, in order to even out any effects of environmental heterogeneity. Species-specific microsatellite loci have been used as molecular markers to identify clones and assess their spatial distribution in both species. As expected, we found an intermingled configuration of genets in the dioecious C. nodosa while Z. noltii was characterized by a clumped, `phalanx-type' distribution of clones. C. nodosa was characterized by higher genotypic diversity with regard to Z. noltii, while heterozygosity levels were comparable in the two species. Coordinating Editor: Dr J. Tuomi     

Response of Callosobruchus maculatus (F.) to varying temperature and relative humidity under laboratory conditions

The effect of temperature and relative humidity were determined on the development of Callosobruchus maculatus (F.) on stored bean (Vigna unguiculata) seeds exposed to five temperatures (20, 25, 30, 35 and 40 °C) and six relative humidity levels (40, 50, 60, 70, 80 and 90%). Oviposition and total adult progeny responded in a curvilinear pattern to temperature and relative humidity while developmental period presented a linear response. Egg laying (117.33 ± 3.21) and adult emergence (35.00 ± 1.70) were least at 20 °C and 90% R.H. but those showed the optimal values at 30 °C and 70% R.H. The implication of these findings is that the growth attributes of C. maculatus relate with the weather variables studied in a curvilinear manner and thus quadratic equations generated could be used for the prediction of optimum temperature and relative humidity in a given area for the management of C. maculatus in stored beans.     

Investigations on the efficacy of entomopathogenic nematodes against Spodoptera littoralis (Biosd.) and Galleria mellonella (L.)

Abstract

The infectivity of seven entomopathogenic nematode strains of the families Steinernematidae and Heterorhabditidae were tested against the last instar larvae of the cotton leafworm, Spodoptera littoralis (Biosd.) and the greater wax moth, Galleria mellonella (L.) in a Petri dish and sand column assay. Exposure of the insect species was done at a dose of 100 IJ/ ml. Heterorhabditis sp. ELG., H. indica, Heterorhabditis sp. ELB. were the highest in activity, they gave a 100% mortality to S. littoralis larvae in a Petri dish assay 24 h postexposure. The rest of the strains tested gave mortalities ranged between 50 and 90% at 24 h then 100% after 48 h postexposure . In the sand-column assay strains, Heterorhabditis sp. ELB., S. riobravae and S. carpocapsae were the highest in activity against S. littoralis with 100% mortality within 24 h postexposure. The results of infectivity against G. mellonella showed that H. indica was the highest in the Petri dish assay and H. egyptii was the highest in the sand column assay with 100% mortality after 24 h of exposure. The penetration rate as an indicator of entomopathogenic nematode infection was also evaluated. The highest value was recorded for Heterorhabditis sp. ELB. (62.3%) and S. carpocapsae (61.4%) against S. littoralis in both the Petri dish and sand-column assay, respectively. In the case of G. mellonella, the highest value of penetration was recorded for Heterorhabditis sp. ELG. (68.3%) and S. riobravae (65.00%) in both the Petri dish and sand-column assay, respectively.     

Indirect effects of hiking trails on the community structure and diversity of trunk-epiphytic bryophytes in an old-growth fir forest

Abstract

Forest hiking trails may influence local microclimate and biodiversity, but the effects on community structure and diversity of epiphytic bryophytes on trees are currently unknown. Epiphytic bryophytes on 82 Abies faxoniana Rehder & Wilson tree trunks (41 along the hiking trail edge and 41 controls in the forest interior) were investigated at four heights from the ground (10, 50, 120, and 180 cm). At each site, air temperature and humidity were monitored for 1 year. The light radiation levels and air temperature were higher, and the canopy leaf area index and air humidity lower at the trail edge, indicating deterioration in microclimate, resulting from the trail establishment. The epiphytic bryophyte species richness, community cover, and mean cover of dendroid and pendent growth forms on trunks were significantly lower at the trail edge than the control site, suggesting that trail construction caused these reductions. One marked effect of the presence of the trail was the increase in some sun-loving species and decrease in shade-tolerant species. Moreover, the trail also slightly influenced species richness and epiphytic bryophyte cover at both community and species population levels along the height gradient. Comprehensive analyses showed that microclimate deterioration was mainly driven by the trail establishment, and that the change in micro-climate along the trail, rather than any host traits, played an important role in the declining epiphytic bryophyte community structure and diversity at the trail edge, confirming the initial hypothesis that the presence of a raised boardwalk (hiking trail) indirectly influences epiphytic bryophyte community and diversity by altering the microclimate.