Many environmental factors can influence foraging strategies of predators, such as availability of prey sources. Brown bears feed on many species of animals and plants but Pacific salmon are especially important to their diet. For example, brown bears in the Lake Aleknagik, Alaska ecosystem forage on sockeye salmon as well as other food items. Direct observations and motion-activated cameras have documented bears foraging on salmon but do not reveal variation among individual bears. This study used the distinctive carbon and nitrogen isotope signatures in salmon as a way to assess brown bear diet by processing samples of bear fur collected during the salmon spawning season. As fur sample collection is noninvasive, it provided the opportunity to “resample” bears (individually identified by DNA analysis) multiple times within a season and over the course of multiple seasons. This study demonstrated how various factors, including salmon availability, gender, and location, influence the extent of bear consumption of salmon over time. Understanding the association between brown bear diet and these factors can provide better insight into the importance of both sockeye salmon and alternative food sources to brown bears.

Cleaning is a mutually beneficial relationship, where the cleaner removes and consumes ectoparasites from its clients. Among fishes, the cleaning behavior has evolved several times as a juvenile or facultative feeding strategy, and is often lost in adults. However, a minority of taxa clean almost exclusively across their ontogeny (obligate cleaners). The largest radiation of obligate cleaners are the Caribbean neon gobies (Elacatinus), that evolved with several congeneric non-cleaners, and in parallel with a closely related lineage of facultative cleaners (Tigrigobius). We suspect that obligate cleaning is a specialized trophic ecology tied to an equally specialized feeding morphology that facilitates improved cleaning performance. We coupled micro-CT scanning with the clearing and staining of museum specimens to compare several functional predictors of feeding performance between cleaner gobies and non-cleaners in a phylogenetic context. We also used geometric morphometrics to compare relative changes in head shape and mouth orientation. Obligate cleaning evolved once, and is characterized by a specialized scraping dentition, stouter cranial features, and a more subterminal mouth position relative to non-cleaners. Meanwhile, facultative cleaning evolved at least 2-3 times, and while some species display similar tooth morphologies as the obligate cleaners, they share more in common with non-cleaners. Obligate cleaners also exhibit fewer sexual dimorphic differences, suggesting that the demand for an efficient cleaning morphology trumps sexual selection.

Genetic diversity and gene flow are important to long-term viability in wild populations. In migratory species, gene flow (i.e. dispersal between disparate populations) is inherently influenced by the spatial and temporal components of their migrations. Recent findings have revealed the importance of fine-scale population structure in both space and time in Sockeye Salmon (O. nerka). However, the fitness consequences of this fine-scale structure are unclear. Here we evaluate the biological relevance of fine-scale spatial and temporal homing by examining their effects on a quantitative trait, individual lifetime reproductive success. Salmonids are well-known for their extensive journey from the freshwater stream where they hatch, to the ocean, and back to their home stream (i.e. ‘homing’). Homing behavior is associated with individual fitness; individuals are locally adapted to their natal streams, and dispersers between non-natal streams can have reduced reproductive success. Population structure within individual streams is generally assumed to be random (panmictic). However, individuals may be locally adapted on a finer scale than previously known, both in space (homing within their natal stream) and return timing. Fine-scale spatial and temporal homing may play a role in individual fitness; therefore, it is important to investigate this relationship. We used zero-inflated negative binomial models and a multi-generation pedigree, reconstructed from two populations of Alaskan Sockeye Salmon, to estimate the impact of homing on individual reproductive success (number of offspring per fish). Our results suggest that fine-scale dispersal in both space and time may reduce lifetime fitness. These results have broad implications for fisheries management and habitat conservation: recognizing the connection between reproductive success and return timing could inform within-season fisheries management, helping maintain the genetic diversity associated with local adaptation; likewise, recognizing the connection between individual salmon success and their habitat may promote maintaining natural heterogeneity in salmon streams.

The foraging patterns and populations of predators can provide a better understanding of the nutrient dynamics in ecosystems. Brown bears (Ursus arctos) are a particularly difficult species to study. However, brown bears are a key predator species to study due to their close relationship with Pacific salmon (Oncorhynchus spp.) populations. Noninvasive methods like hair collection and camera traps are emerging as effective ways to study brown bear populations, diet, and behaviors. This study aims to determine whether the use of these methods in the Wood River system (Aleknagik, AK) are unbiased and characteristic of the resident brown bear population. The data used in this study are part of a long-term study (beginning in 2012) taking place in this area involving brown bear predation on sockeye salmon (Oncorhynchus nerka) and other population studies. Using video footage from the 2016 field season, this study analyzes brown bear reactions and avoidance of the barbed wire used to collect hair samples. Expected results are a higher frequency of wire avoidance in adult bears, single bears, during daylight, and equal frequency of avoidance between creeks. The results of this study can establish whether these methods of studying bear populations are accurate, or if they need to be modified to collect more inclusive and representative data. Further study is required to develop a comprehensive appreciation for brown bear populations, habitat use, and other behavioral patterns.

Marine mammal strandings can serve as an indicator of marine ecosystem and mammal population health, providing an opportunity to learn about the life of individual animals prior to their deaths. Existing stranding networks are focused on response to opportunistic reports of stranded or beached marine mammals, which limits their usefulness in establishing baseline data. The Coastal Observation and Seabird Survey Team (COASST) engages volunteers along the western coast of the United States in collecting and reporting data for two effort-based programs, beached birds and marine debris. Looking to the future, COASST hopes to complement information gathered by marine mammal stranding networks by expanding their effort-based surveys to include marine mammals. COASST has already begun this process by asking volunteers to report sightings of marine mammals along with pictures of their beached bird or marine debris finds. These pictures can be used for species identification, and by looking at these photos in correspondence to other survey data such as region, beach, and survey date we can learn about species distribution along the western coast of the United States. We found at least 300 beached pinnipeds, through photo identification we were able to place them into at the least the families Otariidae or Phocidae. Using current literature on marine mammals, pinnipeds specifically, and their identifying characteristics, I aim to map pinniped species distribution and locate hotspots to ultimately test a pinniped species identification key that will be used by COASST volunteers. With this distribution and hotspot identification we will be able to idenify whether pinnipeds follow already established beaching patterns of beached birds or if they differ. These differentiations could lead to more information about the death of marine mammals and allow future research on the death of these animals in more focalized areas. 

Skeletal reduction is a common feature among deep-sea fishes that have diversified from shallow-water relatives, such as snailfishes. These skeletal reductions may be an adaptation to environmental conditions of high pressures, low temperatures, declining luminosity and limited food availability. Snailfishes (family Liparidae) are found across a large bathymetric range (0 – >8,000 m), with intertidal ancestors giving rise to a large clade of deep-sea species. We used microcomputed tomography (micro-CT) to estimate average bone mineral density and examine jaw, pectoral girdle, and neurocranium morphology. Our results suggest at least three mechanisms of skeletal reduction: (1) reduction of bone size, (2) reduction of bone density, and (3) loss of skeletal elements. First, using phylogenetic generalized least squares (PGLS) analysis, we found that the change in cranial dimensions with depth was not uniform. While the size of the maxilla, dentary, and pectoral girdle decreased with greater depth, length of the upper premaxilla and the neurocranium did not vary with collection depth. Second, average density of the lower jaw decreased with increasing depth. Lastly, the ventral suction disc has been lost multiple times within the deep-sea lineage. While all three methods are seen in snailfishes, other groups may use some or all of these mechanisms to different extents. Some mechanisms of skeletal reduction may be more advantageous than others. The extent to which a structure is retained in deep-dwelling fishes may indicate its functional importance. Variable skeletal reduction in the family Liparidae provides insights into the physiological adaptations that allow fishes to survive in deep-water environments. We conclude that some skeletal elements are maintained at the expense of others as fishes balance the functional demands of life in the deep sea.

Genetic differentiation has long been thought to be low in marine environments, mainly due to higher dispersal potential and low barriers to migration. However, many marine species show population structure on relatively small geographic scales. For example, Pacific cod in the Gulf of Alaska is structured in an isolation-by-distance pattern along the coast. Genome wide surveys also identified genes with particularly strong differentiation, especially the zona pellucida (ZP), a sperm-binding complex in the eggs of Pacific cod that determines what sperm will fertilize the egg. When the outermost region of this complex (ZP3) was sequenced and analyzed it was found that the population of Pacific cod around Kodiak Island had far different ZP3 proteins than the population of Pacific cod residing within Prince William Sound, suggesting that the two populations are reproductively isolated. Our study will expand these results by increasing sample sizes and extending the geographic range of sampling towards the west to assess whether differentiation at this gene can also identify populations in the Aleutian Islands and the Bering Sea. Our results would confirm a split of Gulf of Alaska Pacific cod into two large East-West subpopulations, and may also reveal additional population structure. These findings would not only provide insights into reproductive isolation within marine fishes, but would also have large implications for management, as distinct subpopulations must be managed as such.

Imidacloprid (IMI), a neonicotinoid insecticide, is being sought by shellfish growers to control burrowing shrimp (ghost shrimp, Neotropea californiensis) in Willapa Bay and Grays Harbor, Washington. The shrimp destabilize sediments resulting in poor survival and low yields of the commercially harvested Pacific oyster (Crassostrea gigas), threatening the local shellfish industry. A permit for the use of IMI has been denied by the State, Pacific County has declared an economic emergency, and the outcome of an appeal by the growers remains uncertain. We have undertaken studies to determine if un-iodized table salt may be an alternative to IMI, specifically targeting juvenile shrimp (recruits) inhabiting the upper 10-15 cm of the sediment. Studies in 2018 indicated that a 2-3-fold increase in salinity resulted in 100% mortality when juveniles were exposed in artificial seawater. In 2019, we exposed juveniles (3 replicates, 5 shrimp each) within 10 cm of native sediment to five different salt solutions to achieve sediment pore water salinities of 25 (ambient, control), 35, 50, 70, and 100 ppt. Salt solutions were prepared with native seawater, added on top of the sediment (depth = 2 cm), and allowed to percolate through the sediment column for 6 h (low tide). At 6 h, 2 cm of ambient seawater (25 ppt) were added to simulate tidal inundation and allowed to remain on the surface for 12 h (low-high + high low tide) with two subsequent drawdowns and tidal inundations at 25 ppt (total test duration = 48 h). The sediment was then sieved to remove the shrimp and determine mortality. Average survival of controls (25 ppt) was 73.3% whereas none of the shrimp exposed to elevated salinities survived. Additional tests are underway to examine different exposure scenarios. Results to date suggest table salt may be a viable and greener alternative to IMI.