Search

The paper presents the first record of a Chara connivens (Characeae) stand from Fuerteventura (Canary Islands, Spain). The species was previously recorded only on Tenerife and Lanzarote, mostly in marine and artificial habitats. Physicochemical parameters of water and morphological features of the thalli and plant community were analyzed. General habitat requirements of C. connivens populations located in Europe, North Africa, and South-West Asia were reviewed. The newly described stand was located in a natural rock crevice that was part of a riverbed in El Barranco de las Peñitas (Penitas Canyon). This habitat was unshaded and filled with brackish water. C. connivens co-occurred with Cladophora glomerata and Ruppia maritima. Our report on the presence of C. connivens in the Spanish territory of the Atlantic Ocean is the first in almost 40 years. The distribution of C. connivens and its plant associations on the Canary Archipelago are poorly explored, which is why this topic requires further research. [ABSTRACT FROM AUTHOR]

A phytochorological and ecobiological study of the nine species, two subspecies and two varieties of the genera Aeonium and Greenovia in La Gomera is carried out, with special attention to F1 hybridization in nature. To the ten hybrids already described on the island, seven new hybrids were discovered, which are the subject of a separate publication. In all the known hybrids I determined whether the parents were sympatric or allopatric. The geographical coincidence of the parents was a sine qua non requirement for hybridization to occur in all the hybrids known so far, since pollen transfer by biotic and abiotic agents does not function between disjunct areas. The two prezygotic reproductive barriers that currently prevent interspecific hybridization in Aeonium or intergeneric hybridization between Aeonium and Greenovia are the geographic separation of populations and the different flowering times. The ability to survive and reproduce successfully of F1 hybrids in Aeonium and Greenovia is usually lower than that of the parent species and they generally disappear from the environment in the first filial generation without leaving offspring. The fundamental principles that govern F1 hybridization in La Gomera are extracted, and after verifying that they were also fulfilled in the other mountainous islands, they were synthesized in eight principles, which provide an updated vision of hybridization in the genus Aeonium. Citation: Arango O. 2024: Principles governing F1 hybridization in the genera Aeonium and Greenovia in La Gomera, Canary Islands. – Willdenowia 53: 257–268 Version of record first published online on 23 January 2024. [ABSTRACT FROM AUTHOR]

Simple Summary: The presence of batoids in Gran Canaria, Canary Islands, Spain, in the Mid-Eastern Atlantic Ocean, is quite common depending on the species and time of year. For that reason, we examined the behaviour of spiny butterfly rays (Gymnura altavela) in the shallow waters of Gran Canaria, where the species' affinity to certain beaches was analysed according to the time of year and preference for the type of ocean environment. Such knowledge is important given the lack of information available on the species that is nevertheless vital for its sufficient management and conservation. The presence of spiny butterfly rays, Gymnura altavela, in waters less than 20 m deep off the Canary Islands shows marked seasonality, with relatively high abundances in the summer and autumn. Large aggregations of sometimes hundreds of individuals, primarily females, appear in specific shallow areas of the archipelago and seem to be associated with the seasonal variation in water temperature. This seasonal pattern of presence or absence in shallow areas suggests that spiny butterfly rays migrate into deeper waters or other unknown areas during the rest of the year. G. altavela shows sexual dimorphism; in our study, females were larger and more abundant than males, with a sex ratio of 1:18.9. The species' estimated asymptotic length, L∞, was 183.75 cm and thus close to the common length reported for the species (200 cm). The von Bertalanffy growth constant (k) oscillated between 0.210 and 0.310 year−1, as similarly described for the species in the Western North Atlantic off the U.S. coast. From June to November, the seawater temperature oscillated between 19 and 24 °C, and massive aggregations of females occurred at 22–24 °C and in a few specific sandy beaches on the islands. Spiny butterfly rays, mostly females, show a preference for aggregating in shallow waters during summertime, probably conditionate to mating or breeding behaviour. [ABSTRACT FROM AUTHOR]

The specific spatial distribution and habitat association--strongly influenced by environmental factors or competitive interactions--are major issues in ecology and conservation. We located and georeferenced nesting sites of five cliff-nesting raptors (Egyptian vulture Neophron percnopterus [a locally extinct species], common buzzard Buteo buteo, osprey Pandion haliaetus, common kestrel Falco tinnunculus, Barbary falcon Falco peregrinus pelegrinoides), and common raven Corvus corax on one of the most biodiverse hotspot within the Canary Islands (Teno, Tenerife). We used generalized linear models to evaluate the factors affecting abundance, richness, and intra- and interspecific interactions. Raptor abundance increased with slope, shrub-covered area, and habitat diversity, and decreased with altitude, and forested and grassed areas. Richness increased with slope and decreased with altitude. Threatened species (osprey, Barbary falcon, and raven) occupied cliffs farther away from houses and roads, and more rugged areas than the non-threatened species. The models suggested that the probability of cliff occupation by buzzards, falcons, and ravens depended only on inter-specific interactions. Buzzard occupation increased with the distance to the nearest raven and kestrel nests, whereas falcons and ravens seek proximity to each other. Teno holds between 75% and 100% of the insular breeding populations of the most endangered species (osprey and raven), indicating the high conservation value of this area. Our study suggests that the preservation of rugged terrains and areas of low human pressure are key factors for raptor conservation and provide basic knowledge on the community structure and habitat associations to develop appropriated management actions for these fragile island populations. [ABSTRACT FROM AUTHOR]

How the environment influences the transmission and prevalence of disease in a population of hosts is a key aspect of disease ecology. The role that environmental factors play in host-pathogen systems has been well studied at large scales, that is, differences in pathogen pressures among separate populations of hosts or across land masses. However, despite considerable understanding of how environmental conditions vary at fine spatial scales, the effect of these parameters on host-pathogen dynamics at such scales has been largely overlooked., Here, we used a combination of molecular screening and GIS-based analysis to investigate how environmental factors determine the distribution of malaria across the landscape in a population of Berthelot's pipit ( Anthus berthelotii, Bolle 1862) on the island of Tenerife (Canary Islands, Spain) using spatially explicit models that account for spatial autocorrelation., Minimum temperature of the coldest month was found to be the most important predictor of malaria infection at the landscape scale across this population. Additionally, anthropogenic factors such as distance to artificial water reservoirs and distance to poultry farms were important predictors of malaria. A model including these factors, and the interaction between distance to artificial water reservoirs and minimum temperature, best explained the distribution of malaria infection in this system., These results suggest that levels of malaria infection in this endemic species may be artificially elevated by the impact of humans., Studies such as the one described here improve our understanding of how environmental factors, and their heterogeneity, affect the distribution of pathogens within wild populations. The results demonstrate the importance of measuring fine-scale variation - and not just regional effects - to understand how environmental variation can influence wildlife diseases. Such understanding is important for predicting the future spread and impact of disease and may help inform disease management programmes as well as the conservation of specific host species. [ABSTRACT FROM AUTHOR]

The submarine volcano eruption off El Hierro Island (Canary Islands) on 10 October 2011 promoted dramatic perturbation of the water column leading to changes in the distribution of pelagic fauna. To study the response of the scattering biota, we combined acoustic data with hydrographic profiles and concurrent sea surface turbidity indexes from satellite imagery. We also monitored changes in the plankton and nekton communities through the eruptive and post-eruptive phases. Decrease of oxygen, acidification, rising temperature and deposition of chemicals in shallow waters resulted in a reduction of epipelagic stocks and a disruption of diel vertical migration (nocturnal ascent) of mesopelagic organisms. Furthermore, decreased light levels at depth caused by extinction in the volcanic plume resulted in a significant shallowing of the deep acoustic scattering layer. Once the eruption ceased, the distribution and abundances of the pelagic biota returned to baseline levels. There was no evidence of a volcano-induced bloom in the plankton community. [ABSTRACT FROM AUTHOR]

It is generally assumed that episodic nutrient pulses by cyclonic eddies into surface waters support a significant fraction of the primary production in subtropical low-nutrient environments in the northern hemisphere. However, contradictory results related to the influence of eddies on particulate organic carbon (POC) export have been reported. As a step toward understanding the complex mechanisms that control export of material within eddies, we present here results from a sediment trap mooring deployed within the path of cyclonic eddies generated near the Canary Islands over a 1.5-year period. We find that, during summer and autumn (when surface stratification is stronger, eddies are more intense, and a relative enrichment in CaCO3 forming organisms occurs), POC export to the deep ocean was 2–4 times higher than observed for the rest of the year. On the contrary, during winter and spring (when mixing is strongest and the seasonal phytoplankton bloom occurs), no significant enhancement of POC export associated with eddies was observed. Our biomarker results suggest that a large fraction of the material exported from surface waters during the late-winter bloom is either recycled in the mesopelagic zone or bypassed by migrant zooplankton to the deep scattering layer, where it would disaggregate to smaller particles or be excreted as dissolved organic carbon. Cyclonic eddies, however, would enhance carbon export below 1000 m depth during the summer stratification period, when eddies are more intense and frequent, highlighting the important role of eddies and their different biological communities on the regional carbon cycle. [ABSTRACT FROM AUTHOR]

Abstract: Seasonal depth stratified plankton tows, sediment traps and core tops taken from the same stations along a transect at 29°N off NW Africa are used to describe the seasonal succession, the depth habitats and the oxygen isotope ratios (δ18Oshell) of five planktic foraminiferal species. Both the δ18Oshell and shell concentration profiles show variations in seasonal depth habitats of individual species. None of the species maintain a specific habitat depth exclusively within the surface mixed layer (SML), within the thermocline, or beneath the thermocline. Globigerinoides ruber (white) and (pink) occur with moderate abundance throughout the year along the transect, with highest abundances in the winter and summer/fall season, respectively. The average δ18Oshell of G. ruber (w) from surface sediments is similar to the δ18Oshell values measured from the sediment-trap samples during winter. However, the δ18Oshell of G. ruber (w) underestimates sea surface temperature (SST) by 2°C in winter and by 4°C during summer/fall indicating an extension of the calcification/depth habitat into colder thermocline waters. Globigerinoides ruber (p) continues to calcify below the SML as well, particularly in summer/fall when the chlorophyll maximum is found within the thermocline. Its vertical distribution results in δ18Oshell values that underestimate SST by 2°C. Shell fluxes of Globigerina bulloides are highest in summer/fall, where it lives and calcifies in association with the deep chlorophyll maximum found within the thermocline. Pulleniatina obliquiloculata and Globorotalia truncatulinoides, dwelling and calcifying a part of their lives in the winter SML, record winter thermocline (∼180m) and deep surface water (∼350m) temperatures, respectively. Our observations define the seasonal and vertical distribution of multiple species of foraminifera and the acquisition of their δ18Oshell. [Copyright &y& Elsevier]

The genus Usnea is a conspicuous component of the macrolichen vegetation in Macaronesia. Ten species are recognized in the Azorean archipelago: Usnea cornuta Kdrb., U. esperantiana P. Clerc, U. flammea Stirt., U. geissleriana P. Clerc sp. nov., U. krogiana P. Clerc sp. nov., U. macaronesica P. Clerc sp. nov., U. rubicunda Stirt., U. silesiaca Motyka, U. subflaninzea P. Clerc sp. nov., and U. subscabrosa Motyka. All these species occur in the Canary Islands as well. Descriptive, chemical, ecological and distributional data for each species are provided. Species that have been recorded once for the Azores but not seen, or that are doubtful or excluded in this work, are briefly discussed. [ABSTRACT FROM AUTHOR]

1 Published molecular phylogenies show that many plant groups in the Canary Islands are monophyletic despite the fact that the short distance between the islands and Africa should have led to many independent colonization events.2 Low establishment rates of later migrants owing to niche pre-emption by earlier, already established, colonists could explain these patterns. The apparent monophyly is, however, also compatible with multiple colonizations, with later colonizers making only limited contributions to the total gene pool (and therefore being undetected in the molecular phylogeny) or being wiped out by stochastic processes.3 Experimental evidence for niche pre-emption and species-specific interactions in plants is weak, with survival and establishment of a newly immigrant species depending on the overall composition of the community, rather than on the presence of a particular‘ecologically similar’ species.4 Although niche pre-emption might have contributed to the observed patterns of monophyly, we do not think that phylogeographical data from Macaronesia can be taken as evidence for its action in the geological past.Journal of Ecology(2005)doi: 10.1111/j.1365-2745.2005.01005.x [ABSTRACT FROM AUTHOR]

The lacazelline brachiopodPajaudina, with type speciesP. atlantica, was originally described by the author in 1988 from dead and transported shells collected by Dutch CANCAP expeditions to the Canary Islands. Living sites have now been discovered in shallow-water caves on El Hierro and La Palma in the Canary Islands. From photographs and specimens, information has been obtained on life habits and associated biota, the nature of the ptycholophe lophophore, sexually dimorphic characters of the shell and ontogenetic growth stages of the dorsal valve. The latter are shown to be similar to those ofLacazella, as exemplified byL. caribbeanensisfrom the Bahamas, up to the penultimate stage, following which there are repeated furcations of the minor interbrachial lobes not seen inLacazellabut present inOspreyellaLüter&Wörheide. [ABSTRACT FROM AUTHOR]

The article presents a study that explores the levels of polychlorinated biphenyls (PCB) congeners including the coplanar ones in the liver of six shark species collected around the Canary Islands in the North African Atlantic Ocean and to correlate these with their sex, age, size, habitat and diet. The shark samples were collected in the surroundings of the Canary Islands between July 93 and September 94, during spring and summer seasons when the islands were not an industrialized area and only moderately populated, with a petrol refinery located on one of the islands as a possible PCB emission source.