Bentho-pelagic distribution of early stages of softshell clams (Mya arenaria) in tidally contrasted regimes

2006 ◽  
Vol 84 (3) ◽  
pp. 459-472 ◽  
Author(s):  
Sophie LeBlanc ◽  
Gilles Miron
Keyword(s):  
Spatial Scales ◽  
Mya Arenaria ◽  
Bay Of Fundy ◽  
Eastern Canada ◽  
Life Cycle Stages ◽  
Wide Range ◽  
Planktonic Larvae ◽  
Intertidal Habitats ◽  
Intertidal Level ◽  
Softshell Clam

We examined the settlement and recruitment of the softshell clam (Mya arenaria L., 1758) in two tidally contrasted regimes in eastern Canada. The Bay of Fundy (strong tides) and the Northumberland Strait (weak tides) were used to describe the distribution of planktonic larvae and early settlers. These distributions were compared with those of juvenile and adult forms observed in the same intertidal habitats. Results showed that the abundances of planktonic stages were the same at all tidal levels except in one site of the Bay of Fundy. Early settlers varied according to a site × intertidal level interaction. Juveniles and adults also varied according to a similar interaction, most being in the upper intertidal level. Simple linear regressions demonstrated that no relationship exists between the number of planktonic larvae and the number of early settlers. The only significant relationship observed was the one between the number of juveniles (1–5 mm size class) and the number of adults in one of the Northumberland Strait sites. Our results show, through the high spatial resolution and wide range of spatial scales covered by the study, that the dominant regional tidal regime does not have an effect on the distribution of the softshell clam. Local hydrodynamic effects appear to drive the intertidal distribution of the softshell clam life-cycle stages.

scholarly journals On the generation of internal waves by river plumes in subcritical initial conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Mendes ◽  
J. C. B. da Silva ◽  
J. M. Magalhaes ◽  
B. St-Denis ◽  
D. Bourgault ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Internal Waves ◽  
Coastal Waters ◽  
Initial Conditions ◽  
Spatial Scales ◽  
River Plumes ◽  
Wide Range ◽  
Near Shore ◽  
Generation Mechanisms ◽  
Douro River

AbstractInternal waves (IWs) in the ocean span across a wide range of time and spatial scales and are now acknowledged as important sources of turbulence and mixing, with the largest observations having 200 m in amplitude and vertical velocities close to 0.5 m s−1. Their origin is mostly tidal, but an increasing number of non-tidal generation mechanisms have also been observed. For instance, river plumes provide horizontally propagating density fronts, which were observed to generate IWs when transitioning from supercritical to subcritical flow. In this study, satellite imagery and autonomous underwater measurements are combined with numerical modeling to investigate IW generation from an initial subcritical density front originating at the Douro River plume (western Iberian coast). These unprecedented results may have important implications in near-shore dynamics since that suggest that rivers of moderate flow may play an important role in IW generation between fresh riverine and coastal waters.

Marine tube-dwelling diatoms of eastern Canada: descriptions, checklist, and illustrated key

1984 ◽  
Vol 62 (4) ◽  
pp. 778-794 ◽  
Author(s):  
Christopher S. Lobban
Keyword(s):  
New Species ◽  
Northwest Territories ◽  
Common Species ◽  
Bay Of Fundy ◽  
Eastern Canada ◽  
Lawrence Estuary ◽  
The Common ◽  
Living Material ◽  
St Lawrence Estuary ◽  
A New Species

From a study of living materials and specimens in several regional herbaria, a list has been drawn up of all the common and several of the rarer tube-dwelling diatoms of eastern Canada. Descriptions, illustrations of living material and acid-cleaned valves, and a key to the species are provided. Most specimens were from the Atlantic Provinces and the St. Lawrence estuary, but a few were from the Northwest Territories. By far the most common species is Berkeleya rutilans. Other species occurring commonly in the Quoddy Region of the Bay of Fundy, and sporadically in space and time elsewhere, arc Navicula delognei (two forms), Nav. pseudocomoides, Nav. smithii, Haslea crucigera, and a new species, Nav.rusticensis. Navicula ramosissima and Nav. mollis in eastern Canada are usually found as scattered cohabitants in tubes of other species. Nitzschia tubicola and Nz. fontifuga also occur sporadically as cohabitants.

Responses of insect pests, pathogens, and invasive plant species to climate change in the forests of northeastern North America: What can we predict?This article is one of a selection of papers from NE Forests 2100: A Synthesis of Climate Change Impacts on Forests of the Northeastern US and Eastern Canada.

2009 ◽  
Vol 39 (2) ◽  
pp. 231-248 ◽  
Author(s):  
Jeffrey S. Dukes ◽  
Jennifer Pontius ◽  
David Orwig ◽  
Jeffrey R. Garnas ◽  
Vikki L. Rodgers ◽  
...  
Keyword(s):  
Climate Change ◽  
Plant Species ◽  
Invasive Plant ◽  
Insect Pests ◽  
Adelges Tsugae ◽  
Pest Species ◽  
Invasive Plant Species ◽  
Eastern Canada ◽  
Wide Range ◽  
Nuisance Species

Climate models project that by 2100, the northeastern US and eastern Canada will warm by approximately 3–5 °C, with increased winter precipitation. These changes will affect trees directly and also indirectly through effects on “nuisance” species, such as insect pests, pathogens, and invasive plants. We review how basic ecological principles can be used to predict nuisance species’ responses to climate change and how this is likely to impact northeastern forests. We then examine in detail the potential responses of two pest species (hemlock woolly adelgid ( Adelges tsugae Annand) and forest tent caterpillar ( Malacosoma disstria Hubner)), two pathogens (armillaria root rot ( Armillaria spp.) and beech bark disease ( Cryptococcus fagisuga Lind. + Neonectria spp.)), and two invasive plant species (glossy buckthorn ( Frangula alnus Mill.) and oriental bittersweet ( Celastrus orbiculatus Thunb.)). Several of these species are likely to have stronger or more widespread effects on forest composition and structure under the projected climate. However, uncertainty pervades our predictions because we lack adequate data on the species and because some species depend on complex, incompletely understood, unstable relationships. While targeted research will increase our confidence in making predictions, some uncertainty will always persist. Therefore, we encourage policies that allow for this uncertainty by considering a wide range of possible scenarios.

Long-Term Trends in the Occurrence of Disseminated Neoplasia in a Population of Mya arenaria (Softshell Clam) from a New Hampshire Estuary

2021 ◽  
Vol 28 (2) ◽  
Author(s):  
Paul Geoghegan ◽  
Jamie O'Brien ◽  
Charles W. Walker ◽  
MacKenzie Heagy ◽  
S. Anne Böttger
Keyword(s):  
New Hampshire ◽  
Mya Arenaria ◽  
Long Term Trends ◽  
Softshell Clam

scholarly journals Persistent magnetic vortex flow at a supergranular vertex

2018 ◽  
Vol 610 ◽  
pp. A84 ◽  
Author(s):  
Iker S. Requerey ◽  
Basilio Ruiz Cobo ◽  
Milan Gošić ◽  
Luis R. Bellot Rubio
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Vortex Flow ◽  
Spatial Scales ◽  
Magnetic Vortex ◽  
Magnetic Feature ◽  
Magnetic Element ◽  
Flow Maps ◽  
Wide Range ◽  
Intensity Images

Context. Photospheric vortex flows are thought to play a key role in the evolution of magnetic fields. Recent studies show that these swirling motions are ubiquitous in the solar surface convection and occur in a wide range of temporal and spatial scales. Their interplay with magnetic fields is poorly characterized, however. Aims. We study the relation between a persistent photospheric vortex flow and the evolution of a network magnetic element at a supergranular vertex. Methods. We used long-duration sequences of continuum intensity images acquired with Hinode and the local correlation-tracking method to derive the horizontal photospheric flows. Supergranular cells are detected as large-scale divergence structures in the flow maps. At their vertices, and cospatial with network magnetic elements, the velocity flows converge on a central point. Results. One of these converging flows is observed as a vortex during the whole 24 h time series. It consists of three consecutive vortices that appear nearly at the same location. At their core, a network magnetic element is also detected. Its evolution is strongly correlated to that of the vortices. The magnetic feature is concentrated and evacuated when it is caught by the vortices and is weakened and fragmented after the whirls disappear. Conclusions. This evolutionary behavior supports the picture presented previously, where a small flux tube becomes stable when it is surrounded by a vortex flow.

scholarly journals Rainfall spatio-temporal correlation and intermittency structure from micro-γ to meso-β scale in the Netherlands

2021 ◽  
Author(s):  
Thomas C. van Leth ◽  
Hidde Leijnse ◽  
Aart Overeem ◽  
Remko Uijlenhoet
Keyword(s):  
The Netherlands ◽  
Spatial Scales ◽  
Rainfall Variability ◽  
Temporal Structure ◽  
Temporal Correlation ◽  
Exponential Model ◽  
Rain Gauges ◽  
Wide Range ◽  
Spatio Temporal ◽  
Two Parameter

AbstractWe investigate the spatio-temporal structure of rainfall at spatial scales from 7m to over 200 km in the Netherlands. We used data from two networks of laser disdrometers with complementary interstation distances in two Dutch cities (comprising five and six disdrometers, respectively) and a Dutch nationwide network of 31 automatic rain gauges. The smallest aggregation interval for which raindrop size distributions were collected by the disdrometers was 30 s, while the automatic rain gauges provided 10-min rainfall sums. This study aims to supplement other micro-γ investigations (usually performed in the context of spatial rainfall variability within a weather radar pixel) with new data, while characterizing the correlation structure across an extended range of scales. To quantify the spatio-temporal variability, we employ a two-parameter exponential model fitted to the spatial correlograms and characterize the parameters of the model as a function of the temporal aggregation interval. This widely used method allows for a meaningful comparison with seven other studies across contrasting climatic settings all around the world. We also separately analyzed the intermittency of the rainfall observations. We show that a single parameterization, consisting of a two-parameter exponential spatial model as a function of interstation distance combined with a power-law model for decorrelation distance as a function of aggregation interval, can coherently describe rainfall variability (both spatial correlation and intermittency) across a wide range of scales. Limiting the range of scales to those typically found in micro-γ variability studies (including four of the seven studies to which we compare our results) skews the parameterization and reduces its applicability to larger scales.

scholarly journals Unique spatial integration in mouse primary visual cortex and higher visual areas

2019 ◽  
Author(s):  
Kevin A. Murgas ◽  
Ashley M. Wilson ◽  
Valerie Michael ◽  
Lindsey L. Glickfeld
Keyword(s):  
Visual Cortex ◽  
Visual System ◽  
Primary Visual Cortex ◽  
Spatial Information ◽  
Spatial Scales ◽  
Spatial Integration ◽  
Global Features ◽  
Wide Range ◽  
Visual Areas ◽  
Higher Visual Areas

AbstractNeurons in the visual system integrate over a wide range of spatial scales. This diversity is thought to enable both local and global computations. To understand how spatial information is encoded across the mouse visual system, we use two-photon imaging to measure receptive fields in primary visual cortex (V1) and three downstream higher visual areas (HVAs): LM (lateromedial), AL (anterolateral) and PM (posteromedial). We find significantly larger receptive field sizes and less surround suppression in PM than in V1 or the other HVAs. Unlike other visual features studied in this system, specialization of spatial integration in PM cannot be explained by specific projections from V1 to the HVAs. Instead, our data suggests that distinct connectivity within PM may support the area’s unique ability to encode global features of the visual scene, whereas V1, LM and AL may be more specialized for processing local features.

scholarly journals EXPRESS: Sources of Variation In Search and Foraging A Theoretical Perspective

2021 ◽  
pp. 174702182110503
Author(s):  
Alastair David Smith ◽  
Carlo De Lillo
Keyword(s):  
Spatial Scales ◽  
Theoretical Perspective ◽  
Search Space ◽  
Visual Exploration ◽  
Two Dimensional ◽  
Search Behaviour ◽  
Wide Range ◽  
Search Processes ◽  
Sources Of Variation ◽  
The Individual

Search – the problem of exploring a space of alternatives in order to identify target goals – is a fundamental behaviour for many species. Although its foundation lies in foraging, most studies of human search behaviour have been directed towards understanding the attentional mechanisms that underlie the efficient visual exploration of two-dimensional scenes. With this review, we aim to characterise how search behaviour can be explained across a wide range of contexts, environments, spatial scales, and populations, both typical and atypical. We first consider the generality of search processes across psychological domains. We then review studies of interspecies differences in search. Finally, we explore in detail the individual and contextual variables that affect visual search and related behaviours in established experimental psychology paradigms. Despite the heterogeneity of the findings discussed, we identify that variations in control processes, along with the ability to regulate behaviour as a function of the structure of search space and the sampling processes adopted, to be central to explanations of variations in search behaviour. We propose a tentative theoretical model aimed at integrating these notions and close by exploring questions that remain unaddressed.

scholarly journals New records and AMS radiocarbon dates on Quaternary Walrus ( Odobenus Rosmarus ) from New Brunswick

2002 ◽  
Vol 51 (1) ◽  
pp. 107-111 ◽  
Author(s):  
Randall F. Miller
Keyword(s):  
New Brunswick ◽  
New Records ◽  
Temporal Distribution ◽  
Late Glacial ◽  
Bay Of Fundy ◽  
Eastern Canada ◽  
Radiocarbon Dates ◽  
Odobenus Rosmarus ◽  
Sand And Gravel ◽  
Past Summer

Abstract Walrus fossils are occasionally recovered during scallop dragging in the Bay of Fundy and from sand and gravel deposits along the coastline of New Brunswick in eastern Canada. Six new fossils and four new AMS radiocarbon dates significantly increase the information concerning late-glacial to postglacial walrus in New Brunswick. Dates range from about 12 800 BP to 2 900 BP, almost half falling between 9 000 and 10 000 BP. Temporal distribution of walrus, compared to estimates of past summer sea surface temperature, suggest that in the Bay of Fundy walrus occurred in waters ranging from 12 to 15° C.

scholarly journals A new stream and nested catchment framework for Australia

2013 ◽  
Vol 10 (12) ◽  
pp. 15433-15474
Author(s):  
J. L. Stein ◽  
M. F. Hutchinson ◽  
J. A. Stein
Keyword(s):  
Spatial Scales ◽  
Surface Flow ◽  
Stream Network ◽  
Australian Water ◽  
Assessment Tasks ◽  
Australian Continent ◽  
Wide Range ◽  
High Conservation ◽  
Flow Pathways ◽  
Fully Connected

Abstract. Nationally framed assessment and planning assists coordination of resource management activities across jurisdictional boundaries and provides context for assessing the cumulative effects of impacts that can be underestimated by local or regional studies. However, there were significant shortcomings in the existing spatial frameworks supporting national assessment and planning for Australia's rivers and streams. We describe the development of a new national stream and nested catchment framework for Australia that includes a fully connected and directed stream network and a nested catchment hierarchy derived using a modified Pfafstetter scheme. The directed stream network with associated catchment boundaries and Pfafstetter coding respect all distributary junctions and topographically driven surface flow pathways including across the areas of low relief and internal drainage that make up over half of the Australian continent. The Pfafstetter coding facilitates multi-scale analyses and easy tracing and query of upstream/downstream attributes and tributary/main stem relationships. Accompanying the spatial layers are 13 lookup tables containing nearly 400 attributes describing the natural and anthropogenic environment of each of the 1.4M stream segments across the Australian continent at multiple spatial scales (segment, sub-catchment and catchment). The database supplies key spatial layers to support national water information and accounting needs and assists a wide range of research, planning and assessment tasks at regional and continental scales. These include the delineation of reporting units for the Australian Water Resources Assessment, the development of an ecohydrological environment classification for Australian streams and the identification of high conservation value aquatic ecosystems for northern Australia.

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