To explore relationships between spatial distributions of northern shrimp Pandalus eous and environmental factors along the coastline of Honshu Island in the Sea of Japan, we built delta-type two-step generalized additive models (delta-GAM) based on bottom trawl surveys conducted in 2013–2022. The models provide the first quantitative analysis of the species’ habitat, showing that its distribution is associated with bottom sediment type, depth, slope and topographic position index (TPI) alongside the effects of year and region. From the delta-GAM response plots, species habitat preferences in the Sea of Japan were estimated as follows: seafloor deeper than 283 m; muddy rather than sandy bottoms; gently sloped to flat bottoms (<0.8° in slope); and valleys rather than ridges (TPI < 0.9). These results were reviewed in detail along with previously reported distribution records of northern shrimp. Standardized density (s-density) per fishing grid cell (10′ square latitude–longitude mesh) estimated from the delta-GAM results indicated that this species is widely distributed on the continental slope along the coast of Honshu Island. To test plausibility of the s-density analysis, we compared s-density per fishing grid cell with nominal CPUE (kg per haul) per fishing grid cell based on official logbook data from large offshore trawl fisheries. The two were generally positively correlated by year, and the delta-GAM results were assumed to be fairly robust. Finally, potential fishing grounds were explored based on the delta-GAM results.

The Horikawa index and the local signature are introduced for relatively minimal fibered surfaces whose general fiber is a non-hyperelliptic curve of genus 4 with unique trigonal structure.

Let G be a group, and let g be a nontrivial element in G. If some nonempty finite product of conjugates of g equals the identity, then g is called a generalized torsion element. We say that a knot K has generalized torsion if $G(K) = \pi _1(S^3 - K)$ admits such an element. For a $(2, 2q+1)$ -torus knot K, we demonstrate that there are infinitely many unknots $c_n$ in $S^3$ such that p-twisting K about $c_n$ yields a twist family $\{ K_{q, n, p}\}_{p \in \mathbb {Z}}$ in which $K_{q, n, p}$ is a hyperbolic knot with generalized torsion whenever $|p|> 3$ . This gives a new infinite class of hyperbolic knots having generalized torsion. In particular, each class contains knots with arbitrarily high genus. We also show that some twisted torus knots, including the $(-2, 3, 7)$ -pretzel knot, have generalized torsion. Because generalized torsion is an obstruction for having bi-order, these knots have non-bi-orderable knot groups.

Functional traits play a key role in driving plant community effects on ecosystem function. We examined nine functional traits in various palm (Arecaceae) species and their relationships with moisture, tree-fall gaps, slope, and forest type at 29 transects (500×5 m) in the northeastern region of the Colombian Amazon. Redundancy analysis of mean trait values of species within a plot weighted by their abundance and Pearson correlations were used to evaluate the relationships between traits and environmental factors. The community trait composition was correlated with local environmental factors, which explained 23% of the trait variance. We detected functional dominance of the tallest palms in soils with high moisture and in floodplain forests (p ≤0.05). Palms with relatively long leaves were dominant in the flooded forests. Acaulescent and small palms were dominant on high slopes, and in terra firme forests, long-petioled palms were dominant in forest gaps. The number of seeds per fruit was not correlated with any environmental variable. Thus, hydrology is one of the main drivers of the functional composition of neotropical palm communities at the local scale, segregating tall palms with competitive and evasive strategies from small understory palms, which are mainly stress tolerant.

Reservoirs cause hydrological changes (i.e., water level stabilization) that favor the colonization of aquatic macrophytes. Knowing the ecological factors that determine the occurrence of these plants is critical for water management (e.g., plant control) and biodiversity conservation. In this sense, the present study investigated colonization patterns of Ludwigia sedoides in Lajeado reservoir (Tocantins River, Amazon Basin), in order to identify variables that influence colonization at habitat scale. We investigated the relationship between colonization (coverage area and occurrence) and morphometric (fetch, slope, depth and distance from shoreline) and biotic variables (local diversity of macrophytes and co-occurrence patterns). Stepwise regression selected fetch, depth and slope as the best variables to explain the variation in L. sedoides coverage, which together explained 46% of data variability. Fetch and slope were negatively correlated with coverage, whereas depth showed a positive correlation. No biotic variable was included in the model (P>0.05). However, the investigation of the geometric shape of bivariate correlations (null models) showed positive relationships with local species richness and richness of life forms (i.e., submerged, emergent, floating and epiphytic). In addition, an analysis of species co-occurrence (C-score) revealed that L. sedoides is negatively associated with some macrophyte species. We believe, however, that these results may be associated with species preferences for particular environmental conditions. In conclusion, the present study indicated that morphometric variables are potential predictors of the colonization of L. sedoides in Lajeado reservoir. Sheltered sites with low slope and moderate depths represent favorable environment for colonization and growth.

Five genera and eight species of gastropods of families Conidae and Conilithidae were observed in their natural habitats on the southernmost portion of the Mesoamerican Barrier Reef, off the northern coast of Roatan Island, Honduras. Fifty per cent of species are widespread Caribbean–western Atlantic species, whereas 50% are endemic to the Nicaraguan biogeographical subprovince and Roatan Island. Multiple sightings during night SCUBA diving operations revealed that the reef off northern Roatan supports a healthy and diverse population of conoidean gastropods. Distribution of all recorded species by depth and habitat type revealed a distinct reef partitioning between the 4 most commonly occurring species.

Nothria and Anchinothria, two sister genera of onuphid worms were studied from eastern Australian waters. Nothria abyssia, with a wide distribution in Pacific and Antarctic waters is reported from slope depths south-east of Australia, while N. otsuchiensis, described from Japanese waters, was found along the eastern coast of Australia from shallow subtidal to deep slope areas. Anchinothria parvula sp. nov. is described, based on the presence of uni- and bidentate pseudocompound falcigers in the first three pairs of parapodia, absence of branchiae and appearance of limbate chaetae from chaetiger 2, subacicular hooks from chaetigers 6–8 and pectinate chaetae from chaetiger 14. The new species represents the first record of the genus in Australian waters. Ontogenetic variation of chaetal composition and morphology of parapodia was estimated in two Nothria species examined. Three size-related morphotypes with different chaetal composition and morphology of anterior falcigers were revealed in N. abyssia and N. otsuchiensis. The number of chaetigers with pseudocompound falcigers is the only character independent of size of the specimens in both examined species. Distribution of subacicular hooks and postchaetal lobes is shown to be size-dependent. The following characters are considered of diagnostic value only when scored in adults: presence/absence of simple falcigers in anterior parapodia; chaetiger of origin of limbate chaetae, pectinate chaetae, and subacicular hooks; and number of chaetigers with auricular prechaetal lobes and digitiform postchaetal lobes. The use of adult specimens with the final set of definitive morphological structures for diagnoses of Nothria species is suggested.

Understanding how wood decomposition varies spatially at the mesoscale (between 1-ha plots) may improve carbon flux estimates in Amazonian forests. An experiment was carried out to test the influence of soil, slope, above-ground tree live biomass (biomass), fine-litter mass and characteristics of neighbouring trees on the variation of wood decomposition between 1-ha plots in four species of tropical trees that vary in wood density (Manilkara huberi – 0.86 g cm−3, Couratari guianensis – 0.54 g cm−3, Hura crepitans – 0.32 g cm−3 and Parkia pendula – 0.29 g cm−3). A wood sample from each species (30 × 5 × 2.5 cm) was placed in each of 71 plots within 64 km2 of terra firme tropical moist forest in Reserva Florestal Adolpho Ducke. One year later, samples were collected and weighed. The effects of specificity of decomposers was measured by the association of decomposition with the wood density and with the taxonomic group of the nearest tree with dbh ≥30 cm. Wood decomposition was independent of soil (texture and nutrients), slope, biomass and fine-litter mass at the mesoscale, except for C. guianensis, which showed greater decomposition in locations with greater biomass. Decomposition was also independent of wood density and taxonomic group of nearby large trees. In general, none of the variables was useful as a predictor of wood decomposition at the scale larger than 1 ha. Thus, the use of models that include soil and topography to improve estimates of carbon flux are limited because wood decomposition does not follow similar mesoscale patterns to that of biomass and fine-litter decomposition. Also, the results indicate that wood decomposition is more likely to be associated with generalist decomposers than with specialists associated with neighbouring trees.

Soil water potentials were measured weekly by psychrometers at 20 cm depth during the dry season in a tropical moist forest on Barro Colorado Island, Panama. There was a persistent gradient of decreasing soil moisture from gap centre to gap edge to adjacent understorey at both a large and a small gap. On both a north-south and an east-west transect, the soil was drier (water potentials were more negative) on an upland surface than on moderate slopes. This trend was reflected in the predawn, total water potentials of shallow-rooted Psychotria horizontalis and deep-rooted Trichilia tuberculata measured in the understorey during the last two months of the dry season. P. horizontalis from the wettest sites on the transects had higher osmotic potentials at full hydration and at zero turgor, indicating less drought resistance than for conspecifics from the driest sites.

Many studies suggest that edaphic variables are major determinants of frog distributions. However, leaf-litter depth and soil characteristics are influenced by distance from streams, so the apparent relationship between edaphic characteristics and species distributions could be an artefact of the dependence of species on free water for reproduction. Therefore, we investigated the effect of edaphic variables on the mesoscale distribution of frog species not dependent on free water for reproduction. We evaluated the effects of soil texture, pH, slope, number of trees and leaf-litter volume on the distribution of nine terrestrially reproducing anuran species in the Reserva Ducke, a 100-km2 terra firme forest preserve in central Amazonia. Diurnal and nocturnal assemblages of anuran species were sampled in 72 plots systematically distributed across the reserve. We sampled the diurnal anuran assemblage by visual encounter in 250 × 1-m plots and the nocturnal assemblage in 250 × 20-m plots using both auditory and visual surveys. The majority of terrestrially breeding anuran species were influenced by topographic and/or edaphic variables, such as slope, soil clay content and pH. However, responses to environmental predictors differed among species. Most species occurred throughout all environmental gradients and relationships with soil characteristics were subtle, indicating that these species occur in the majority of habitats in Reserva Ducke. The results of this study indicate that terrestrially breeding frogs are habitat generalists that show little mesoscale beta diversity associated with habitat variation.

Différents aspects de la conservation, de l'aménagement et de la revitalisation des cours d'eau sont présentés par la description des concepts, des méthodes, des matériaux et des résultats obtenus. Une place particulière est faite aux méthodes du génie végétal permettant d'atteindre des résultats hydroécologiques fonctionnels. Les fondements sont expliqués, de même que les paramètres à prendre en compte pour qu'une opération soit réussie au point de vue technique et surtout biologique. Le génie végétal s'inscrit dans un contexte de développement durable des hydrosystèmes utilisés par l'Homme, basés sur la conservation ou la réimplantation de systèmes dynamiques rivulaires disparus. Il s'inscrit, tout comme d'autres «génies», dans la panoplie des techniques à disposition des ingénieurs pour résoudre certains problèmes d'érosion. L'ensemble de l'article donne une information et un état des connaissances actuelles sur le génie végétal. Il est cependant clairement démontré qu'il utilise les plantes vivantes comme matériaux de construction permettant d'obtenir des ouvrages extrêmement fonctionnels et durables. Il n'emploie pas les végétaux comme éléments cosmétiques de décoration d'ouvrage de génie civil ! Toute intervention sur un cours d'eau n'étant pas forcément souhaitable, l'opportunité d'une variante zéro est envisagée. La philosophie devant prévaloir aux aménagements de cours d'eau se base sur une logique naturelle qui veut que le végétal, selon les cas, soit privilégié avant le minéral : - 1) Déterminer s'il y a réellement lieu de devoir intervenir en fonction des impacts et des enjeux (variante zéro) - 2) Evaluer si les techniques végétales peuvent satisfaire à la résolution des problèmes.- 3) En cas contraire, établir si des techniques combinées peuvent pallier aux problèmes. - 4) Seulement à ce stade, appliquer une technique habituelle de génie civil pour autant qu'elle s'avère raisonnable et proportionnée. Aménager un cours d'eau n'est pas qu'une simple affaire de calculs hydrauliques. Une connaissance des fonctions biologiques est nécessaire à l'élaboration des concepts d'intervention. Une analyse fine de l'ensemble du cours d'eau selon des critères hydroécologiques s'avère aujourd'hui indispensable. Pour mener à bien la conception d'une conservation, d'un aménagement naturel ou d'une revitalisation de cours d'eau, des directives sont proposées.