Evaluation and Comparison of a Habitat Suitability Model for Postdrift Larval Lake Sturgeon in the St. Clair and Detroit Rivers

We evaluated composition and spatial distribution of riverine nursery habitat for larval Lake Sturgeon Acipenser fulvescens in the Middle Channel of the St. Clair River, Michigan, and Fighting Island Channel of the Detroit River, Ontario, using a habitat suitability model (HSM) and fish collections. Although model outputs indicated similar portions of high‐quality habitat in the Middle Channel (16.9%) and Fighting Island Channel (15.7%), larval abundance and dispersal patterns varied between these systems. Analysis with Akaike’s information criterion indicated that a regression model using sand–silt substrate performed best at predicting the observed water‐volume‐standardized CPUE (number of larvae·h−1·m−3) in the Middle Channel. Of 93 larvae that were collected in the Middle Channel, most were found to cluster at three distinct areas of high‐ and moderate‐quality habitat, which was composed predominately of sand–silt substrate. Lengths of larvae varied by as much as 9 mm, and the degree of yolk sac absorption also varied, indicating that larvae in the Middle Channel remained within the channel after a short drift downstream. Of the 25 larvae that were collected in Fighting Island Channel, distribution was sporadic, and occurrence did not significantly correlate with measured habitat variables. Larvae were relatively homogeneous in size and yolk sac stage, indicating that newly emerged larvae did not utilize available habitat in Fighting Island Channel but instead drifted into the main channel of the Detroit River. Dispersal patterns indicate variability in young Lake Sturgeon ecology, which is dependent on local habitat conditions—most notably, substrate composition. Furthermore, modeled larval–habitat associations found in this study were compared to a similar study on larval Lake Sturgeon from the North Channel of the St. Clair River. Model outputs from all three systems accurately accounted for observed larval dispersal patterns among both rivers. This supports the transferability of an HSM parameterized for Lake Sturgeon from individual river reaches within two large river systems.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146299/1/nafm10217.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146299/2/nafm10217_am.pd

Complete breeding failures in ivory gull following unusual rainy storms in North Greenland

Natural catastrophic events such as heavy rainfall and windstorms may induce drastic decreases in breeding success of animal populations. We report the impacts of summer rainfalls on the reproductive success of ivory gull (Pagophila eburnea) in north-east Greenland. On two occasions, at Amdrup Land in July 2009 and at Station Nord in July 2011, we observed massive ivory gull breeding failures following violent rainfall and windstorms that hit the colonies. In each colony, all of the breeding birds abandoned their eggs or chicks during the storm. Juvenile mortality was close to 100% at Amdrup Land in 2009 and 100% at Station Nord in 2011. Our results show that strong winds associated with heavy rain directly affected the reproductive success of some Arctic bird species. Such extreme weather events may become more common with climate change and represent a new potential factor affecting ivory gull breeding success in the High Arctic

Growth, Female Size, and Sex Ratio Variability in American Eel of Different Origins in Both Controlled Conditions and the Wild: Implications for Stocking Programs

Freshwater eels Anguilla spp. are declining worldwide, and a major challenge is understanding why these panmictic species show contrasting patterns of intraspecific phenotypic variation and recruitment. We present results on studies of the American Eel A. rostrata to understand and discriminate the effects of origin and plasticity on growth and sex determination. We considered two separate growth and one length‐at‐age data sets. The first growth data set originated from a 34‐month rearing experiment starting from the glass eel life stage to test the effects of origin, salinity, and density on growth and sex determination. The second growth data set originated from a shorter rearing experiment of 18 months starting at the yellow eel stage (around 3 years old) and compared transplanted individuals in Lake Ontario (LO) with natural migrants to the LO area. The third data set compared transplanted individuals in LO sampled by electrofishing with naturally migrating individuals. Sex ratios were identical for all origins and treatments in the long‐term growth experiment (34–35% females). While male size distribution had little variability, certain female groups had a large variation in growth and presented fast‐ and slow‐growing clusters. On the other hand, both cases of natural migrants to the LO area were consistent with being only slow‐growing females. We found that wild individuals rearing in the LO area were nearly exclusively transplanted individuals and that males, as well as fast‐growing females, were present. Even though the entire species is panmictic, these results support a role for spatially varying selection in explaining the phenotypic variation observed among regions and among individuals of the same region, and such factors must be considered for any successful management strategies of American Eel

Проектирование и разработка сайта кафедры (на примере сайта кафедры технологий программирования)

Проектирование и разработка сайта кафедры (на примере сайта кафедры технологий программирования): аннотация к дипломной работе / Глеб Владимирович Бондарчук; БГУ, Факультет прикладной математики и информатики, Кафедра технологий программирования; науч. рук. Войтешенко И. С