Seasonal Movements, Habitat Utilization, and Comparative Scale Morphology of White Marlin (Kajikia albida) and Roundscale Spearfish (Tetrapturus georgii)

Recent studies have demonstrated that the morphologically similar white marlin (Kajikia albida) and roundscale spearfish (Tetrapturus georgii) co-occur in the western North Atlantic, including the U.S. Mid‐Atlantic Bight. Differences in scale morphology have been proposed as one morphological character to discriminate these species, but a thorough analysis of scale morphology is lacking. Because the validity of the roundscale spearfish was not established until 2006, much of the biological information previously collected for “white marlin” may include data for both white marlin and roundscale spearfish. The objectives of this study were to obtain a better understanding of the movements and habitat utilization of positively identified white marlin that inhabit the U.S. Mid-­‐Atlantic Bight during summer months, and to describe the morphological variation of white marlin and roundscale spearfish scales. Eleven long‐term (6 or 12 month) pop-up satellite archival tags were placed on white marlin that were caught and released in the U.S. recreational fishery. Nine tags reported information on temperature, pressure (depth), and light levels for light‐based geolocation for periods of 8 days to 12 months. Most fish moved out of the Mid-Atlantic Bight in September, and overwintered in areas ranging from east of the Gulf Stream off the Carolinas to the Caribbean, and as far south as northern Brazil. of the seven fish that retained tags for more than 40 days, five spent time in known spawning grounds in waters of the Dominican Republic leading up to the spring spawning season. These data demonstrate a large degree of connectivity among white marlin in the western North Atlantic. as noted in previous studies, individuals spent a large proportion of their time in the surface waters (0-10m; 75% across all white marlin pooled), the vast majority of their time in the top 100 m of the water column (97%), and within eight degrees of sea surface temperature (98%), although definite shifts in habitat utilization were evident as fish departed coastal offshore waters of the Mid‐Atlantic Bight. Diel habitat utilization varied greatly, with white marlin spending 81% of total nighttime in the surface waters (0‐10m), and only 26% of total daytime in surface waters. Past studies have characterized the scales of white marlin and roundscale spearfish as being morphologically distinct, but little effort has been made to describe variation within an individual, among individuals, or between species. to better understand morphological variation of scales and squamation patterns of distinct body regions of these two species, individual scales were collected from 11 specific anatomical regions, and scale patches were collected from 3 specific regions of each white marlin and roundscale spearfish brought into marlin tournament weigh stations in the Mid-Atlantic Bight during 2012 and 2013. Scales were measured and described, and scale patches were cleared and stained to examine the level of imbrication of the scales, as well as the overall squamation patterns. In addition to the scales, denticular plates, ossified formations occurring on the surface layer of the dermis, were measured and described. Although considable morphological variation was observed among scales from different anatomical regions of individuals of both species, white marlin scales generally have pointed anterior ends, fewer posterior points, and are more heavily imbricated than those of roundscale spearfish, which are frequently rounded anteriorly, but often have many posterior points and are farther separated within the skin. Over all areas and individuals, roundscale spearfish scales were significantly wider and had a lower length-­‐to-­‐width aspect ratio than those of white marlin. Detailed scale descriptions allow for a more accurate characterization of the variation within and differences between these two species, and could potentially be a valuable tool for investigating istiophorid systematics

TB191: Conservation and Management of Native Bees in Cranberry

Threats to agriculturally important pollinators have serious implications for human beings. A loss of bees translates to less successful crop pollination, thus reduced yield and poorer quality fruits. Native bees have the potential to serve as commercial pollinators. A diverse pollinator complex comprised of both honey bees and native bees should result in stable pollination levels and should be resistant to threats such as disease, fluctuating honey and crop prices, and honey bee transportation costs. Adding the goal of native bee conservation to land management increases the ecological integrity of an ecosystem by conserving a unique biological interaction that is the basis for most native wild plant reproduction. This report describes pollination in the cranberry agroecosystem and outlines steps to take to manage native bees in cranberry.https://digitalcommons.library.umaine.edu/aes_techbulletin/1017/thumbnail.jp

Methane-Oxidizing Seawater Microbial Communities from an Arctic Shelf

Marine microbial communities can consume dissolved methane before it can escape to the atmosphere and contribute to global warming. Seawater over the shallow Arctic shelf is characterized by excess methane compared to atmospheric equilibrium. This methane originates in sediment, permafrost, and hydrate. Particularly high concentrations are found beneath sea ice. We studied the structure and methane oxidation potential of the microbial communities from seawater collected close to Utqiagvik, Alaska, in April 2016. The in situ methane concentrations were 16.3 ± 7.2 nmol L−1 , approximately 4.8 times oversaturated relative to atmospheric equilibrium. The group of methaneoxidizing bacteria (MOB) in the natural seawater and incubated seawater was \u3e 97 % dominated by Methylococcales (γ -Proteobacteria). Incubations of seawater under a range of methane concentrations led to loss of diversity in the bacterial community. The abundance of MOB was low with maximal fractions of 2.5 % at 200 times elevated methane concentration, while sequence reads of non-MOB methylotrophs were 4 times more abundant than MOB in most incubations. The abundances of MOB as well as non-MOB methylotroph sequences correlated tightly with the rate constant (kox) for methane oxidation, indicating that non-MOB methylotrophs might be coupled to MOB and involved in community methane oxidation. In sea ice, where methane concentrations of 82 ± 35.8 nmol kg−1 were found, Methylobacterium (α-Proteobacteria) was the dominant MOB with a relative abundance of 80 %. Total MOB abundances were very low in sea ice, with maximal fractions found at the ice– snow interface (0.1 %), while non-MOB methylotrophs were present in abundances similar to natural seawater communities. The dissimilarities in MOB taxa, methane concentrations, and stable isotope ratios between the sea ice and water column point toward different methane dynamics in the two environments

Measurements and analysis of the upper critical field Hc2H_{c2} on an underdoped and overdoped La2−xSrxCuO4La_{2-x}Sr_xCuO_4 compounds

The upper critical field $H_{c2}$ is one of the many non conventional properties of high-$T_c$ cuprates. It is possible that the $H_{c2}(T)$ anomalies are due to the presence of inhomogeneities in the local charge carrier density $\rho$ of the $CuO_2$ planes. In order to study this point, we have prepared good quality samples of polycrystalline $La_{2-x}Sr_xCuO_{4}$ using the wet-chemical method, which has demonstrated to produce samples with a better cation distribution. In particular, we have studied the temperature dependence of the second critical field, $H_{c2}(T)$, through the magnetization measurements on two samples with opposite average carrier concentration ($\rho_m=x$) and nearly the same critical temperature, namely $\rho_m = 0.08$ (underdoped) and $\rho_m = 0.25$ (overdoped). The results close to $T_c$ do not follow the usual Ginzburg-Landau theory and are interpreted by a theory which takes into account the influence of the inhomogeneities.Comment: Published versio

Protein Pattern Formation

Protein pattern formation is essential for the spatial organization of many intracellular processes like cell division, flagellum positioning, and chemotaxis. A prominent example of intracellular patterns are the oscillatory pole-to-pole oscillations of Min proteins in \textit{E. coli} whose biological function is to ensure precise cell division. Cell polarization, a prerequisite for processes such as stem cell differentiation and cell polarity in yeast, is also mediated by a diffusion-reaction process. More generally, these functional modules of cells serve as model systems for self-organization, one of the core principles of life. Under which conditions spatio-temporal patterns emerge, and how these patterns are regulated by biochemical and geometrical factors are major aspects of current research. Here we review recent theoretical and experimental advances in the field of intracellular pattern formation, focusing on general design principles and fundamental physical mechanisms.Comment: 17 pages, 14 figures, review articl