A satellite-based Lagrangian perspective on Atlantic Water fractionation in the Nordic Seas

<p>The Arctic Ocean has been receiving more of the warm and saline Atlantic Water in the past decades. This water mass enters the Arctic Ocean via two Arctic gateways: the Barents Sea Opening and the Fram Strait. Here, we focus on the fractionation of Atlantic Water at these two gateways using a Lagrangian approach based on satellite-derived geostrophic velocities. Simulated particles are released at 70N at the inner and outer branch of the North Atlantic current system in the Nordic Seas. The trajectories toward the Fram Strait and Barents Sea Opening are found to be largely steered by the bottom topography and there is an indication of an anti-phase relationship in the number of particles reaching the gateways. There is, however, a significant cross-over of particles from the outer branch to the inner branch and into the Barents Sea, which is found to be related to high eddy kinetic energy between the branches. This cross-over may be important for Arctic climate variability.</p>

Phenolic and Lipophilic Extractives in Scots Pine Knots and Stemwood

Summary The phenolic and lipophilic extractives in the heartwood of knots from seven Scots pine trees were analysed by GC, GC-MS and HPSEC. The knots contained large amounts of phenolic stilbenes, 1–7% (w/w), and lignans, 0.4–3% (w/w), while the stemwood contained around 1% (w/w) of stilbenes and no detectable lignans. In young trees without stem heartwood the stilbene content in the knots was up to 200 times that in the stem. Some in-tree and between-tree variation was seen in the content of phenolic compounds in the knots. The ratio of pinosylvin monomethyl ether to pinosylvin was higher in the knots than in the stemwood. The most abundant lignan was nortrachelogenin, but also matairesinol, secoisolariciresinol and liovil were present in small amounts in the knots. The knots also contained a complex mixture of lignan-like compounds, here called oligolignans. The flavonoid pinocembrin was present in both stemwood and knots in amounts below 0.02% (w/w). The stilbene concentration in the radial direction, from the pith to the outer branch, decreased or was on the same level inside the stem, while it decreased markedly in the outer branch. The lignan concentration was on the same level or decreased slightly inside the stem, while it decreased markedly in the branches and became almost non-existent within 10 cm out in the branches. The knots contained large amounts (4.5–32% (w/w)) of lipophilic extractives, mainly resin acids. Some in-tree and between-tree variation was seen for the resin acids. The abietane-type resin acids dominated over the pimarane-type acids and abietic acid was the most abundant resin acid in the knots and in stem heartwood. The amount of resin acids in the radial direction decreased or was on the same level inside the stem, while a clear decrease was detected in the branches. The profile of the distribution of resin acids and phenolic compounds was similar. The knots also contained up to 0.5% (w/w) of diterpenyl aldehydes.

Lignans and Lipophilic Extractives in Norway Spruce Knots and Stemwood

Summary The hydrophilic and lipophilic extractives in the heartwood of knots from 7 Norway spruce trees were analysed by GC, GC-MS and HPSEC. The knots contained extremely large amounts of lignans, 6–24% (w/w), with hydroxymatairesinol comprising 65–85% of the lignans. Even the knots of the young trees contained 4–8% (w/w) of lignans. The variation in the amount of lignans was large among knots, both within a single tree and between trees. In addition to the lignans, knots also contained 2–6% (w/w) of a complex mixture of lignan-like compounds with 3, 4 and even up to 6 phenyl propane units, here called oligolignans. The amounts of lignans in the knots were similar in the radial direction from the pith into the outer branch, but decreased dramatically outwards in the branch, almost disappearing after 10–20 cm. The ratio of the 2 epimers of hydroxymatairesinol differed between different knots and even within the knot. A new spruce lignan, nortrachelogenin, or its enantiomer, wikstromol, was detected in knots from trees in northern Finland as opposed to samples from southern Finland. The amount of lipophilic extractives was small compared to the amount of hydrophilic extractives in the knots. Five of the dead knots contained more resin acids and free diterpenyl alcohols than ordinary stemwood. In the other knots, the amount of lipophilic extractives was on the same level as stem heartwood. The stem sapwood contained larger amounts of esterified fatty acids than the knots.

Emeraldella and Leanchoilia, two arthropods from the Burgess Shale, Middle Cambrian, British Columbia

The type species of two much discussed but hitherto poorly known genera of arthropods are described in detail from new preparations. Illustrations are by photographs, explanatory line drawings, and reconstructions including three-dimensional models. The convex body of Emeraldella brocki was not trilobed, and was divided into a cephalon with labrum and 13 trunk somites, the first 11 having pleurae which were progressively narrower (transversely (tr.)) and more backwardly curved posteriorly, the last two somites being cylindrical, with a long posterior spine inserted into the 13th. A bilobed, spinose, ventral anal plate was probably attached to the 12th somite; the alimentary canal may have terminated in the 13th somite. The cephalon bore long antennae and five pairs of limbs, the first short, uniramous and jointed, the second to fifth biramous, the outer branch elongate-oval and having marginal filaments, the inner branches jointed and progressively longer. Trunk somites 1—11 each bore a pair of biramous limbs, the outer branch bilobed and with filaments on the distal margins, the jointed inner branches long on the anterior six or seven pairs. The coxae of the entire limb series bore a spinose gnathobase on the mesial edge, and the proximal podomeres of the leg branches were spinose. The outer branches were attached to the coxa and possibly the first podomere of the inner leg branch. The maximum known length of the body (excluding the posterior spine) was 65 mm; the animal lacked eyes, and was a benthonic predator and scavenger, walking on and digging into the muddy bottom, the gnathobases enabling soft food to be squeezed, shredded and passed forward along the midline to the backward-facing mouth. The outer branches were presumably gills, and may have aided in feeble swimming. Leanchoilia superlata had a smooth, convex, faintly trilobate exoskeleton. The head shield was subtriangular with an upturned snout. The 11 tergites had broad (tr.) pleurae, behind the fifth progressively narrower (tr.) and more backward-curving; the 11th was curved back beside a short, triangular tail spine, which bore lateral spines. Anteriorly the cephalon bore the great appendage, which consisted of a basal section and four additional stout podomeres shaped to curve through 90°. The second and third podomeres were each extended by a tapering shaft continued by a longer, annulated portion. The distal podomere consisted of a tapering shaft terminating in three claws and a long, annulated extension. The remainder of the body had 13 pairs of biramous appendages (two on the cephalon, one on each trunk somite), the outer branch a lobe having overlapping lamellae on the distal and posterior margins, the inner branch tapering, of some eight podomeres and terminal spines. The proximal portions of the appendages are not preserved, but the outer branch was attached so that the inner branch lay below the anterior border of the outer branch; the two branches were of similar length (tr.) and hung down below the body. The alimentary canal is preserved, filled anteriorly with apatite, the filling showing segmentation and annulation. The mouth was apparently downward- and forward-facing, and led into a bulbous foregut situated beneath the cephalon. The anus opened on the 11th trunk somite. The maximum known length of the body was 68 mm. The animal lacked eyes and was probably benthonic in habit, able to rest on the sediment surface on the great appendage and the tips of the inner branches and to swim over it by metachronal movements of the outer branches (which also acted as gills), the great appendage swung back beneath the body to reduce resistance. It was probably a detritus feeder, the food pushed into the midline by the limbs, the mouth presumably suctorial. There is no evidence of a labrum, or of gnathobasic basal podomeres, but the inner margin of the leg branch was setiferous. The single species of Emeraldella , E.brocki, is recognized, and the type and only specimen of ‘ Emeraldoides ’ is referred to it. Synonymous with Leanchoilia superlata are Walcott’s three species L. major, Bidentia difficilis and Emeraldella micrura, and Simonetta’s Leanchoilia amphiction , L. persephone and L. protogonia . Emeraldella brocki may be allied with Molaria spinifera ; problematical is any relationship to aglaspidids. Leanchoilia superlata may be most closely related to Actaeus armatus . Emeraldella and Leanchoilia are very different from one another, and from either Sidneyia or Naraoi a; these four genera are so heterogeneous that Stormer’s grouping of them into the taxon Merostomoidea is rejected as no longer useful.

Rare arthropods from the Burgess Shale, Middle Cambrian, British Columbia

Six species of arthropods from the Walcott Collection, U.S. National Museum, are described. Molaria spinifera Walcott is known from over 100 specimens, a sample that reveals the morphology fairly fully. Between one and 12 specimens of the other species are known, and yield limited information. M. spinifera had a smooth, convex exoskeleton, not trilobed, the cephalic shield being a quarter-sphere in shape, eight trunk tergites diminishing in size posteriorly and the cylindrical telson having a short ventral spine and a long, jointed posterior spine. The cephalon bore a pair of short, slim antennae and three pairs of biramous appendages. There were eight pairs of similar biramous appendages on the trunk. The biramous appendage had a large basal podomere, a segmented inner walking branch, and a lobate outer branch arising from the basal podomere and bearing marginal lamellae. The sagittal length of cephalon, trunk and telson ranged from 8 to 26 mm, the posterior spine slightly exceeding this length; the smallest specimens are similar to the largest. The animal lacked eyes, and was probably benthic and may have been a scavenger and deposit feeder. Habelia optata Walcott was superficially similar to M . spinfera , the trunk being of 12 tergites; there was no cylindrical telson, but a ridged and barbed spine inserted into the 12th tergite, the spine having a joint at about two-thirds its length. The external surface of the exoskeleton was tuberculate; the pleurae of the tergites curved back increasingly strongly posteriorly, the tips being spinose. The cephalon appears to have borne a slim, short pair of antennae and two pairs of biramous appendages; the proximal portions of the jointed inner branches may have been adapted for grinding food. The first six trunk somites bore biramous limbs, the inner branch being a relatively long walking leg, the outer a lobe having marginal lamellae; on the posterior trunk somites there is no trace of the inner branch, but the outer was present. H. optata lacked eyes and was probably a benthic animal. Only the smooth exoskeleton of a possible second species, H? brevicauda Simonetta, is known, of which the posterior spine is short and bluntly rounded. The new genus and species Sarotrocercus oblita is erected for a few specimens, in which the body is about 1 cm in length, and behind which is a slim spine having a group of spines at the tip. From beneath the anterolateral margin of the cephalic shield a large eye projected, and the cephalon bore also one pair of large, jointed appendages. Behind these were pairs of lobed appendages bearing marginal lamellae, one on the cephalon and one on each of the nine trunk somites. This small species may have drifted and swum in the higher water layers, the occasional carcass lying on the sea bottom having been preserved. The single specimen of Actaeus armatus Simonetta is over 6 cm in length. The exoskeleton of this specimen is divided into cephalic shield with marginal eye lobe, 11 trunk tergites and a triangular terminal plate. The anterior cephalic appendage was Leanchoil -like, the stout proximal portion being curved and ending in a group of claws, the next two podomeres bearing long, slim extensions. The head shield also bore three pairs of biramous appendages, consisting of a small jointed inner branch and a large lobed outer branch with marginal lamellae; appendages like these outer branches are preserved beneath the trunk tergites. Only two specimens are identified as Alalcomenaeus cambricus Simonetta (length 3-4 cm). The exoskeleton is divisible into cephalic shield, trunk of probably 12 tergites, and an ovate terminal plate which has lateral bands. The cephalon has a marginal eye lobe and an anterior appendage which is broad proximally, the long distal portion being slim. The holotype shows a series of lobed appendages, the first three cephalic. Between them project the curved, pointed terminations of inner branches. The second specimen suggests that these lobed appendages bore marginal filaments, and reveals the inner branches as blade-shaped, and spinose on the inward-facing margin. These biramous appendages were present on all the trunk somites, being largest anteriorly. These remarkable appendages suggest a benthic scavenger, able to hold on to, and tear up, a carcass. ‘ Leanchoilia protogonia ’ Simonetta is most probably a composite, a poorly preserved Leanchoilia superlata lying on an unidentified, branching organism. The five species showing appendages extend greatly the known range of variation in morphology of the Burgess Shale arthropods. Affinities are discussed, but familial and higher classification is postponed, pending completion of work on all the arthropods from the shale.

The Middle Cambrian trilobite Naraoia , Burgess Shale, British Columbia

The type species of the genus, N.compacta , is described from new preparations and measurements of over 100 specimens from C. D. Walcott’s original collection, and 5 from the recent re-investigation. Photographs and explanatory drawings provide the basis for considerations of mode of preservation, and lead to a new reconstruction. The dorsal exoskeleton was divided by a single articulation into two shields, each moderately convex with a raised axial region, the subcircular anterior shield overlapping for a short distance the longer posterior shield; narrow reflexed doublure on both shields. Dorsal surfaces of shields smooth, without transverse furrows, eyes absent. Axial region of anterior shield widest posteriorly, extending forward to threequarters length of shield, labrum may have been present under anterior portion. Axial region of posterior shield tapered back, reaching close to posterior margin of shield. Alimentary canal may be preserved filled with sediment, and was probably U-shaped anteriorly, broadest beneath anterior portion of axial region, tapering back to tip of posterior shield. Two types of alimentary diverticula preserved as reflective bands on anterior shield; single trunk of lateral diverticula ran transversely at mid-length and ramified beneath lateral region of shield; three pairs of axial diverticula, one per segment, originated behind main trunk of lateral diverticula and ramified in posterior part of axial region. Axial diverticula, one per segment and not ramifying, appear to have been present beneath the axial region of the posterior shield. Paired areas of muscle attachment, preserved as reflective or pyritous areas, are segmentally arranged along the axial region, one pair close together at the anterior extremity. One pair of long, uniramous, multi-jointed antennae was attached beside anterior extremity of axial region, followed by a maximum of 19 pairs of similar biramous appendages, three pairs on the posterior part of the anterior shield, remainder beneath posterior shield. Large triangular coxa strongly spinose on adaxial margin; inner, leg branch of five podomeres and terminal, thorn-like spine; large, spinose endite on proximal podomere. Outer branch arose from abaxial, dorsal margin of coxa, and consisted of slim, tapering shaft with terminal lobe, dorsal margin of shaft bore many long, thin, upward and backwardly directed lamellae. Specimens range in length from 9 to 40 mm, some 40 % of the sample being cast dorsal exoskeletons, the remainder whole animals. About one-fifth of the sample bore a posterolateral spine on the anterior shield, rather than having a rounded angle. This difference was recently used to erect two new species, Naraoia halia and N. pammon ; here it is taken as the sole evidence of dimorphism in the single species N. compacta . A second species, N. spinfer , is recognized from two poorly-preserved specimens, characterized by seven pairs of lateral spines and a median posterior spine on the margins of the posterior shield; the axial region is poorly defined and appendages virtually unknown. N. compacta is considered to have been a benthonic predator and scavenger, walking, digging and raking in search of food much as did the trilobite Olenoides serratus , and to have had poor swimming powers. The lamellate outer branch of the appendage is regarded as a gill branch, aerated by currents produced when walking and swimming or drifting. There is no evidence of an abdomen or telson, so that N. compacta is a trilobite-like animal lacking the articulated thorax; it is regarded as representing a separate order of class Trilobita.

TWO NEW HOMOPTERA FROM AFRICA, AND SYNONYMICAL NOTES

Scaphoideus Anneœ, sp. nov.—Different from all the other species of Scaphoideus known to me, by the presence of only one median subapical cell in the tegmina, instead of two: the subcostal (marginal) cell widens apically, the outer branch of the raidal vein being continuous up to the apex of the tegmen, not ending at the base of teh subapical cells as in the other species. The interolateral margins of the eyes are straight, diverging very slightly towards the dorsal apex, and the posterior margin of the pronotum is a little more emarginate.