We conducted field experiments in the nearshore area of two urban lakes (Lake Washington and Lake Sammamish) in western Washington to test the attractive quality of artificial nighttime lighting to subyearling salmonids Oncorhynchus spp. In both lakes, experimental trials were conducted along a uniform 156‐m shoreline section twice a month (one night with lights and one control night without lights) from March to May to correspond with peak nearshore rearing of subyearling salmonids. We examined the effects of three light intensities on nearshore fish abundance: (1) no light, (2) dim light (maximum, 5.0 lx), and (3) bright light (maximum, 50.0 lx). These were compared with abundances from control nights without light treatments. Beach seining was used to determine fish abundance. For each month, the total number of subyearling salmonids (Chinook Salmon O. tshawytscha, Coho Salmon O. kisutch, and Sockeye Salmon O. nerka combined) was greater on the lighted nights (all treatments combined) than it was on the control nights. In both lakes, the most subyearling salmonids were collected in the bright‐light treatments, an intermediate amount in the dim‐light treatments, and few in the no‐light treatments. In some instances, subyearling salmonid abundances in the bright‐light treatments were more than 10 times greater than in the no‐light treatments. The effect of nighttime artificial lighting was generally more pronounced in March than in April or May. The results support our hypothesis that subyearling salmonids exhibit nocturnal phototaxic behavior when exposed to elevated nighttime lighting. A major concern of artificial nighttime lighting for subyearling salmonids is the potential for an increased predation risk, and we believe the prudent management goal would be to minimize artificial nighttime lighting.
Received October 23, 2016; accepted March 7, 2017 Published online May 26, 2017
This paper presents a computational model that integrates a dynamically structured holographic memory system into the ACT-R cognitive architecture to explain how linguistic representations are encoded and accessed in memory. ACT-R currently serves as the most precise expression of the moment-by-moment working memory retrievals that support sentence comprehension. The ACT-R model of sentence comprehension is able to capture a range of linguistic phenomena, but there are cases where the model makes the wrong predictions, such as the over-prediction of retrieval interference effects during sentence comprehension. Here, we investigate one such case involving the processing of sentences with negative polarity items (NPIs) and consider how a dynamically structured holographic memory system might provide a cognitively plausible and principled explanation of some previously unexplained effects. Specifically, we show that by replacing ACT-R's declarative memory with a dynamically structured memory, we can explain a wider range of behavioral data involving reading times and judgments of grammaticality. We show that our integrated model provides a better fit to human error rates and response latencies than the original ACT-R model. These results provide proof-of-concept for the unification of two independent computational cognitive frameworks.
We examined the effects of potential barriers on populations of migratory sculpins (Coastrange Sculpin Cottus aleuticus and Prickly Sculpin C. asper) and fluvial sculpins (Riffle Sculpin C. gulosus, Shorthead Sculpin C. confusus, and Torrent Sculpin C. rhotheus). Barriers can alter sculpin distribution because migratory sculpins have pelagic larvae that drift downstream to calm waters and juveniles and adults migrate upstream. We compared sculpin populations upstream and downstream of a barrier in 19 lowland streams in the Puget Sound region, Washington. Within each stream, we examined the farthest downstream barrier that would be most likely to impact the upstream movements of migratory sculpins. All study streams had populations of migratory sculpins in stream reaches downstream of the barrier. In 8 of the 19 streams with a barrier, at least one species of fluvial sculpin was also present. We also documented the relative distribution of migratory sculpins and fluvial sculpins in one reference stream without a barrier. In all streams examined, the density of migratory sculpins upstream of the barrier was lower than that downstream of the barrier and the differences were statistically significant. In 12 of the 19 streams, migratory sculpins were not present upstream of the barrier. In streams with fluvial sculpin populations, fluvial sculpins were usually rare downstream of barriers and were statistically less abundant than upstream of the barrier. The migratory sculpins collected upstream of barriers were statistically larger than those collected downstream of barriers. In the reference stream, migratory sculpin species dominated the lower stream reaches and were gradually replaced by fluvial sculpin species in more upstream reaches. Overall, barriers appear to have an important effect on the distribution of both migratory sculpins and fluvial sculpins, which should be taken into account when assessing habitat modifications and fish communities in Puget Sound lowland streams.
Received November 4, 2016; accepted March 25, 2017 Published online June 12, 2017
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