Spatial pattern of coniferous and deciduous forest patches in an Eastern North America agricultural landscape: the influence of land use and physical attributes

In agricultural landscapes, most studies have investigated the influence of the spatial pattern of forest patches on other ecological phenomena and processes, such as animal movement and biodiversity. However, few have focused on explaining the spatial pattern of the forest patches themselves. Understanding how these patterns relate to the processes that generate them is fundamental in developing a sound theory of landscape ecology, and in devising rational management strategies. In this paper, the pattern of the overall forest patches, as well as the pattern of deciduous and coniferous patches in an agricultural landscape of Southern Quebec, Canada, were analyzed and related to landscape physical attributes and land use, using remote sensing, geographic information systems and statistical methods. Results show that the role of landscape physical attributes on forest patch pattern has been modified by land use. In the study area, coniferous or deciduous patches are not associated with a specific surface deposit. In addition, physical attributes explain only a small proportion of the abundance of conifers on past abandoned land compared with land-use factors. Physical attributes only indirectly influence the forest pattern because they strongly influence the land-use practices. Our results reveal a conifer recovery process with the abandonment of agricultural land. On past abandoned land, conifers expand with increasing stand age, mostly by invasion from neighboring coniferous patches. Spatially, coniferous patches are usually located on the margins of the overall forest patches, and they are connected to non-forest land-use types such as crop and pasture, the latter being the most important. By showing the importance of some coniferous forest types that did not exist in the precolonial forest, a new perspective emerges when landscape, especially, land-use dynamics are taken into account.     

Assessment of the dark-adaptation time required for recovery of electroretinographic responses in dogs after fundus photography and indirect ophthalmoscopy

OBJECTIVE: To investigate the duration of dark-adaptation time required for recovery of electroretinographic responses after fundus photography or indirect ophthalmoscopy in dogs. ANIMALS: 6 dogs. PROCEDURE: Initially, scotopic-intensity series of electroretinograms (ERGs) were recorded after 20 minutes of dark adaptation. The fundus of the left eye of each dog was photographed (n = 10) or examined via indirect ophthalmoscopy for 5 minutes with moderate- (117 candela [cd]/m2) or bright-intensity (1,693 cd/m2) light; ERGs were repeated after a further 20 or 60 minutes of dark adaptation (6 procedures/dog). RESULTS: Following 20 minutes of dark adaptation after fundus photography, the b- and a-wave amplitudes were reduced in response to brighter stimuli, compared with pretest ERGs; after 60 minutes of dark adaptation, ERG amplitudes had recovered. Following 20 minutes of dark adaptation after indirect ophthalmoscopy (moderate-intensity light), significantly lower b-wave amplitudes were recorded in response to 2 of the brighter flash stimuli, compared with pretest ERGs; after 60 minutes of dark adaptation, ERG amplitudes had recovered. Following 20 minutes of dark adaptation after indirect ophthalmoscopy (bright-intensity light), all ERG amplitudes were significantly decreased and implicit times were significantly decreased at several flash intensities, compared with pretest ERGs; after 60 minutes of dark adaptation, ERG amplitudes and implicit times had returned to initial values, except for b-wave amplitudes recorded in response to dimmer stimuli. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that at least 60 minutes of dark adaptation should be allowed before ERGs are performed in dogs after fundus photography or indirect ophthalmoscopy.     

Is serotonin uptake by peripheral tissues sensitive to hypoxia exposure?

Fish Physiology and Biochemistry - In the Gulf toadfish (Opsanus beta), the serotonin (5-HT) transporter (SERT) is highly expressed in the heart, and the heart and gill both demonstrate the...     

Analysis of environment-recruitment associations for a coastal red drum population reveals consistent link between year class strength and early shifts in nearshore winds

The identification of factors contributing to strong year classes of marine fishes has been a constant goal toward a mechanistic understanding of recruitment variability. Here, we explored a 26-year time series of the abundance of early juvenile red drum along the North Carolina coast to identify environmental features associated with variable recruitment success. The study location was near the northern edge of the species latitudinal range, and we hypothesized that consistent environmental forcing would be linked to the formation of strong red drum year classes. Patterns of variability in seasonal environmental features were disaggregated into multiple forms of temporal periodicity and analyzed using generalized additive models. We also contrasted patterns of environmental variation that occurred during the strongest recruitment events with those coinciding with the weakest red drum year classes. The early shift, during August, to favorable wind conditions was the most consistent environmental feature associated with red drum recruitment success. The combined duration and magnitude of N and NE winds during August of strong recruitment years was nearly double the level observed during weak recruitment years. Elevated nearshore sea surface temperatures early in the spawning season were also found to occur during years that produced strong year classes. Coastal productivity, indexed using chlorophyll a concentration, was positively associated with red drum recruitment, but also highlighted the need for more spatially resolved productivity data. Our findings highlight the importance of environment-recruitment linkages for marine fishes, especially near distributional boundaries where conditions to promote year class success can be brief.     

Determination of Acid Volatile Sulfides and Chromium Reducible Sulfides in Cu-Zn and Au Mine Tailings

The present study investigated the use of chemical extractions for the determination of acid volatile sulfides (AVS) and chromium reducible sulfides (CRS) in sulfidic mine tailings from Au and Cu-Zn mines. The main objectives of the study were to understand the factors affecting AVS and CRS extraction in mine tailings and to use the AVS and CRS data as indicator of biotic reactions, including microbial sulfate-reduction. Tailings from one Cu-Zn mine and two Au mines located in the Timmins area, Ontario, Canada, were extracted for AVS and CRS, along with pure metal sulfides. Tailings were also characterized by XRD and the relative abundance of pyrite and pyrrhotite in the samples was determined. Our results showed that AVS in mine tailings were generally not extractable at cold temperature, but they could be extracted from most tailings samples at ～ 80 °C. AVS extraction of pure metal sulfides showed that pure pyrrhotite was partially soluble during cold and hot extractions and that it significantly contributed to the overall AVS fraction of the tailings. Such findings complicate the use of AVS as bio-indicators of microbial activity because a large fraction of the pyrrhotite present in the tailings originated from the ore deposit. The CRS fractions were found to be unaffected by the presence of pyrrhotite and truly represented the pyrite content of the tailings. The use of AVS and CRS data from mine tailings can be helpful in assessing the distribution of metal sulfides but attention must be paid to their true significance.     

A possible role of coarse fractionated radiotherapy in the management of gingival squamous cell carcinoma in dogs: A retrospective study of 21 cases from two referral centers in the UK

Surgery with or without the addition of radiotherapy is the treatment of choice for canine oral squamous cell carcinoma (SCC). Fractionated radiotherapy alone is also effective in the long-term control of the disease, however coarse fractionated radiotherapy (CF-RT) for gingival SCC has not been extensively reported. The aim of this study was to describe side effects, clinical response, and median survival time (MST) of dogs with gingival SCC treated with CF-RT in the palliative and adjuvant setting. Twenty-one cases from two referral centres in the UK treated with CF-RT for gingival SCC between July 2013 and June 2019 were retrospectively evaluated. Of the 21 dogs, 11 developed mild acute adverse effects. Oral mucositis was the most common radiation induced toxicity. Three dogs developed chronic severe adverse effects (oro-nasal fistula, bone necrosis and gum recession). Overall clinical response rate was 77% in dogs receiving palliative treatment with MST of 365 days (60–1,095 days). MST was not reached for dogs treated in the adjuvant setting with a mean of 466 days (121–730 days). In cases of advanced gross disease CF-RT might have a role in short term palliation of clinical signs. However, it carries a significant risk of late toxicity for cases with unexpectedly long survival times and further investigations are required to identify an optimal CF-RT protocol. Randomized controlled trials are needed to confirm the role of CF-RT as adjuvant treatment of incompletely resected gingival SCC.