In gaining word knowledge, children’s semantic representations are initially imprecise before becoming gradually refined. We developed and tested a framework for a digital receptive vocabulary assessment that captured varied levels of representation as children learn words. At pre-test and post-test, children selected one of four images to match a word’s meaning: a correct target, a conceptually-related foil, a thematically-related foil, and a phonologically-similar foil. We expected that selecting a conceptually related foil would indicate that the word is understood at a deeper level than selecting a phonologically similar foil. Indeed, selection of phonological foils decreased from pre- to post-test, while selection of more advanced thematic and conceptual foils increased. These results demonstrate that this assessment tool probed semantic knowledge that might be characterized as intermediate word knowledge. The current paper presents a novel and sensitive way to capture the incremental process of word learning. Applications for vocabulary interventions are discussed.

As a generalization of random recursive trees and preferential attachment trees, we consider random recursive metric spaces. These spaces are constructed from random blocks, each a metric space equipped with a probability measure, containing a labelled point called a hook, and assigned a weight. Random recursive metric spaces are equipped with a probability measure made up of a weighted sum of the probability measures assigned to its constituent blocks. At each step in the growth of a random recursive metric space, a point called a latch is chosen at random according to the equipped probability measure, and a new block is chosen at random and attached to the space by joining together the latch and the hook of the block. We use martingale theory to prove a law of large numbers and a central limit theorem for the insertion depth, the distance from the master hook to the latch chosen. We also apply our results to further generalizations of random trees, hooking networks, and continuous spaces constructed from line segments.

Here, we report the first sighting records of Bryde's whales in Nicaragua. Four sightings were made in 2022 during boat-based surveys off the southwestern coast of Nicaragua. Photo-identification, distributional data, dive times, and behavioural information were collected, and environmental parameters, including sea surface temperature, were measured for each sighting. Sightings included calf and non-calf groups displaying travelling (n = 1; 25%), milling (n = 1; 25%), and suspected feeding (n = 2; 50%) behaviours. Approximately 4 h of focal following allowed the calculation of short and long breath intervals. Based on our observations, the individuals were suspected of feeding in the area, based on the presence of feeding birds, feeding humpback whales, relatively high time-lagged chlorophyll-a, and observed general behaviours. Our findings indicate that this species may occasionally visit Nicaraguan coastal areas in search of feeding opportunities, and could represent a possible range extension of the Eastern North Pacific stock.

The species composition and distribution of marine invertebrates varies greatly in different bathymetric regions. Nevertheless, the process of exchange between faunas of different depths has occurred repeatedly throughout the evolution of marine biodiversity. In high latitudes, this process should occur most actively due to absence of strong temperature stratification. The presence of physiological adaptations that allow northern shallow-water organisms to live at greater depth has been demonstrated in a series of experiments. However, known cases of recent colonization by species confined to a highly productive shallow-water zone in unusually deeper Arctic habitats are almost absent. The present study describes finding of population of the gastropod Onoba aculeus (Gould, 1841) in two samples from the lower continental shelf of the Arctic Ocean. Onoba aculeus is a shallow-water amphiatlantic species widely distributed in the temperate regions. The finding reported here is at the same time, the northernmost, easternmost, and most remote from the coast location. We assume that the detection of molluscs indicates the presence of an abundant isolated population in the region.

The sustainability of an agricultural field is largely influenced by crop growth habit and management practices such as tillage. Both strongly interact to shape ecosystem properties such as the fluxes and stocks of carbon and nitrogen. Recently, researchers have worked to develop perennial grain crops in order to enhance key ecosystem processes, such as carbon cycling and nitrogen fixation, with the use of perennial crops rather than traditionally used annual crops. In this study, we aimed to understand how soil disturbance combined with vegetation type [annual monoculture crops vs. perennial monocultures (intermediate wheatgrass (IWG)) vs restored native vegetation (RNV)] influenced the soil carbon and nitrogen dynamics. We collected soil samples at two depths (0–15 cm and 15–30 cm) from each vegetation treatment and incubated the soils in the laboratory for 120 days to determine the efflux of carbon and also analyzed the mineralization of both carbon and nitrogen. The results demonstrated the soils from the IWG had the greatest carbon flux, as well as carbon and nitrogen storage (annual monoculture < RNV < IWG). The differences in carbon flux, carbon and nitrogen storage from the IWG to the annual monoculture were 27, 40, 20%, respectively, while the IWG to the RNV was 11, 20, 10%. Shallow soil samples exhibited greater differences in all C and N comparisons between treatments compared to deeper soil samples. Taken together, our findings indicate that crop vegetation type and soil depth strongly influence carbon and nitrogen dynamics.

The elimination of unwanted catch in mixed species fisheries is technically challenging given the complexity of fish behaviour within nets. Most approaches to date have employed technologies that modify the nets themselves or use physical sorting grids within the gear. There is currently increasing interest in the use of artificial light to either deter fish from entering the net, or to enhance their escapement from within the net. Here, we evaluated the differences in catch retained in a standard otter trawl, relative to the same gear fitted with a square mesh panel, or a square mesh panel fitted with LEDs. We found that the selectivity of the gear differed depending on water depth. When using a square mesh panel in shallow depths of 29–40 m the unwanted bycatch of whiting and haddock was reduced by 86% and 58% respectively. In deep, darker water (45–95 m), no change in catch was observed in the square-mesh panel treatment, however when LEDs were added to the square-mesh panel, haddock and flatfish catches were reduced by 47% and 25% respectively. These findings demonstrate the potential to improve the performance of bycatch reduction devices through the addition of light devices to enhance selectivity. The results also highlight species-specific and site-specific differences in the performance of bycatch reduction devices, and hence a more adaptive approach to reduce bycatch is probably required to maximize performance.

The physiology of mesophotic Scleractinia varies with depth in response to environmental change. Previous research has documented trends in heterotrophy and photosynthesis with depth, but has not addressed between-site variation for a single species. Environmental differences between sites at a local scale and heterogeneous microhabitats, because of irradiance and food availability, are likely important factors when explaining the occurrence and physiology of Scleractinia. Here, 108 colonies of Agaricia lamarcki were sampled from two locations off the coast of Utila, Honduras, distributed evenly down the observed 50 m depth range of the species. We found that depth alone was not sufficient to fully explain physiological variation. Pulse Amplitude-Modulation fluorometry and stable isotope analyses revealed that trends in photochemical and heterotrophic activity with depth varied markedly between sites. Our isotope analyses do not support an obligate link between photosynthetic activity and heterotrophic subsidy with increasing depth. We found that A. lamarcki colonies at the bottom of the species depth range can be physiologically similar to those nearer the surface. As a potential explanation, we hypothesize sites with high topographical complexity, and therefore varied microhabitats, may provide more physiological niches distributed across a larger depth range. Varied microhabitats with depth may reduce the dominance of depth as a physiological determinant. Thus, A. lamarcki may ‘avoid’ changes in environment with depth, by instead existing in a subset of favourable niches. Our observations correlate with site-specific depth ranges, advocating for linking physiology and abiotic profiles when defining the distribution of mesophotic taxa.

The coast of Brazil is an important low latitude nursery ground for humpback whales (Megaptera novaeangliae). The number of humpback whales in this region has increased and its population is reoccupying areas where it has been depleted during the whaling period. The goal of this study was to conduct land-based observations during 2014 and 2015 to characterize patterns of habitat use and relative abundance of humpback whales that migrate to one of these reoccupation areas: Serra Grande, Bahia state. The observed mean group size was 2.12 ± 0.96 individuals and did not vary through the reproductive season nor between years. Dyads (32.9%) and singletons (26.7%) were more frequently observed, and groups with calves represented 21.2% of the sightings. The mean number of whales counted per hour increased from 2014 (3.44 ± 3.35) to 2015 (5.12 ± 4.18). Habitat use varied during the season; whales used shallower waters closer to shore as the season progressed. The spatial distribution of groups with calves was dependent on the presence and number of escorts. Spatial segregation of groups with calves closer to shore is a key factor in understanding the overall distribution of whales in the area, suggesting that social strategies are affected by environmental factors, as seen in other wintering grounds. Small-scale studies from land-based stations, in areas such as this where there is no previous knowledge about the species, are cost effective. They provide information about the overall behavioural and spatial patterns while anthropogenic activity is still low, allowing habitat protection and management decisions before implementation and increase of human activities.

Fluometuron adsorption and dissipation under field and laboratory conditions, and distribution within the soil profile was determined in 3 soils from Tennessee, Mississippi, and Georgia that are representative of the cotton-growing regions of the southeastern United States. Fluometuron adsorption was correlated with organic matter, but not with clay content or soil pH. First-order kinetics explained fluometuron dissipation under field and controlled conditions (r 2 ≥ 0.82). Field dissipation of fluometuron was slower under dry conditions. Fluometuron was not detected below 15 cm in the soil profile in any soil, and concentrations in the 8- to 15-cm soil zone were < 15 ppbw 112 d after treatment. Fluometuron dissipation was more rapid in soil from the 0- to 8-cm depth in Tennessee soil than in Mississippi soil under controlled conditions. Dissipation was more rapid under field conditions than under laboratory conditions at 2 of 3 locations. Fluometuron half-lives in soils from the 0- to 8-cm depth ranged from 9 to 28 d under field conditions and from 11 to 43 d in the laboratory. Fluometuron dissipation in soils from 30- to 45- and 60- to 90-cm depths was not different among soils, with half-lives ranging from 58 to 99 d under laboratory conditions. Fluometuron half-life was positively correlated with soil depth and inversely correlated with organic matter. These data indicate that organic matter, soil depth, and environmental conditions affect fluometuron dissipation.

Fall panicum (Panicum dichotomiflorum Michx.) seed were found to be dormant at harvest. This dormancy was overcome by an after-ripening period of 17 to 22 weeks, alternating germination temperatures (10 C for 16 h and 30 C for 8 h), stratification, and mechanical or chemical scarification. Soaking seed in gibberellic acid (GA3) or thiourea for 1 day, or washing seed in running tap water for up to 96 h before seed were placed in a germinator, had no effect on dormancy. In the greenhouse, fall panicum emergence was greatest (82%) when seed were placed on the growth media surface. The maximum number of seedlings (39%) emerged in the field when seed were placed 1.3 cm below the soil surface, although some emerged from as deep as 5.1 cm.

Wild oat control options are limited in western Canada due to resistance to most common herbicides. Control of wild oat with pyroxasulfone, a soil-applied, very-long-chain fatty-acid inhibitor, was investigated. A series of greenhouse and field experiments were conducted to isolate the effects of vertical seed position, site of herbicide interception, and tillage on wild oat control with pyroxasulfone in comparison with triallate. In greenhouse experiments, wild oat shoot length (soil surface to leaf tip) was reduced (P<0.05) in shallow-seeded wild oat compared with deep-seeded wild oat with pyroxasulfone (6.2 and 9.8 cm, respectively) and triallate (3.7 and 13.2 cm, respectively). Soil-applied pyroxasulfone remained in the top 2.5 cm of the soil with or without a simulated rainfall event. Pyroxasulfone was most effective if either the seed or the shoot 1 cm above the seed intercepted the herbicide layer. If a wild oat emerges from deeper in the soil profile, the sensitive part of the seedling may not intercept an effective rate of pyroxasulfone in the soil. In field experiments comparing deep- and shallow-seeded wild oat treated with pyroxasulfone and triallate in fields with and without tillage, there were no significant effects of tillage alone on wild oat shoot length. Deep-seeded wild oat emerged early, and while herbicides reduced shoot growth, shoots were >10 cm. Shallow-seeded wild oat had delayed emergence, possibly due to reduced soil moisture, and herbicides reduced shoot growth to <10cm. Pyroxasulfone is likely to be more effective in no-till fields where wild oat seeds are not located deep in the soil.

Goosegrass is considered one of the most important grassy weeds of rice, particularly in rain-fed environments. Experiments were conducted in laboratory, screenhouse, and field to study the germination ecology of goosegrass seeds. In the laboratory, germination was greater at higher alternating temperatures (30/20 and 35/25 C) than at the lowest alternating temperatures (25/15 C). An after-ripening period of at least 3 mo was required to improve the germination of goosegrass. Germination was tolerant of salt stress but sensitive to a high degree of water stress. A pH range of 5 to 10 did not influence seed germination (92 to 95%). In the screenhouse study, seedling emergence of goosegrass was greatest (82%) for seeds placed on the soil surface, but decreased exponentially after that, no seedlings emerged at a burial depth of 8 cm. Seedling emergence and seedling dry matter declined markedly with the addition of crop residue to the soil surface at rates equivalent to 4 to 6 ton (t) ha−1. In the field, seedling emergence of goosegrass was greater under zero-till (ZT; 16 to 18%) than under minimum tillage (MINT; 8 to 11%). Because seedling emergence was greater from surface-sown seeds and emergence was favored by ZT, this species is likely to become a problematic weed in ZT systems. The information gained from this study could be used in developing effective weed management strategies.

This study was conducted in the laboratory and screenhouse to determine the effects of temperature, light, osmotic stress, salt stress, burial depth, use of crop residues as mulch, depth of flooding, and use of POST herbicides on the emergence, survival, and growth of doveweed. In the light/dark regime, germination was higher at alternating day/night temperatures of 35/25 C (95%) than at 30/20 C (72%), and no germination occurred at 25/15 C. Light strongly influenced germination (95%) and dark completely inhibited germination. No germination occurred at an osmotic potential of −0.8 MPa and a salt concentration of 150 mM and above. The highest germination (91%) was observed from the seeds sown on the soil surface and emergence decreased by 78, 86, and 92% when burial depths were increased to 0.5, 1, and 2 cm, respectively. No seedlings emerged from seeds buried at depths of more than 2 cm. The use of rice residues as mulch significantly reduced the emergence and growth of doveweed seedlings. The amount of residue required to suppress 50% of the maximum biomass was 2.5 t ha−1. Flooding had a more pronounced effect on seedling biomass than seedling emergence. Biomass was reduced by 78, 92, and 96% when flooding depths increased from 0 to 2, 4, and 6 cm, respectively, for the seeds placed on the soil surface, whereas for the seeds buried at 0.5 cm, these values were 78, 100, and 100%. Bentazon (100 g ha−1) and bispyribac-sodium (30 g ha−1) provided 100% control of doveweed when applied at the three-leaf stage. Doveweed control was less than 31% with glyphosate rates up to 2,000 g ha−1. The application of 2,4-D (500 g ha−1) provided 100% control of doveweed even when applied at the seven-leaf stage. The information from this study could help in developing more sustainable and effective integrated weed management strategies for the control of this weed and weeds with similar response in dry-seeded rice systems.

Weedy rice is a serious problem of cultivated rice in most of the rice-growing areas in Asia, causing increased production costs and yield losses in rice. A study was conducted to determine the response of weedy rice accessions from India (IWR), Malaysia (MWR), Thailand (TWR), and Vietnam (VWR) to seed burial and flooding depths. The greatest emergence for each weedy rice accession (97% for IWR, 82% for MWR, 97% for TWR, and 94% for VWR) was observed in seeds placed on the soil surface. Seedling emergence decreased with increase in burial depth. For the IWR accession, 0.5% of the seedlings emerged from 8-cm depth, whereas for the other three weedy rice accessions, no seedlings emerged from this depth. When seeds were sown on the soil surface, flooding depth ranging from 0 to 8 cm had no or very little effect on seedling emergence of different weedy rice accessions. On the other hand, flooding decreased seedling emergence in all weedy rice accessions when seeds were sown at 1 cm deep into the soil. Compared with seedling emergence, flooding had a more pronounced effect on seedling biomass for all weedy rice accessions. A flooding depth of 2 cm reduced seedling biomass by an amount greater than 85% of each weedy rice accession. The results of this study suggest that emergence and growth of weedy rice could be suppressed by deep tillage that buries seeds below their maximum depth of emergence (i.e., > 8 cm for the accessions studied) and by flooding fields as early as possible. The information gained from this study may help design cultural management strategies for weedy rice in Asia.