Variation in river flow results in the expansion and contraction of the main channel, off-channel habitat, and the physical connections between these components. Hence, rivers are characterized by a mosaic of habitat conditions that shift across space and time. Here, we explore how a stream-dwelling fish integrates across spatial and temporal shifts in the availability of thermal and trophic resources. Across multiple years of variable flow, juvenile coho salmon (Oncorhynchus kisutch) have been observed feeding on an ephemeral food source in the cold main channel at night; returning to warm off-channel habitat during the day where their ability to metabolize large meals is greater. We hypothesize that an analogous tracking strategy is used to take advantage of in-situ prey and a shifting distribution of thermally optimal habitat within a single season. During the early summer in southwest Alaska, high lake levels flood the lower reaches of a third-order stream. As summer progresses, lake levels subside and the spatial distribution of thermal resources and connectivity of habitats within the stream is reduced. Preliminary analysis shows that juvenile coho prey heavily on stoneflies, which are concentrated in the cold main channel. Using snorkel surveys, PIT tagging, and gastric lavage, we will monitor changes in the spatial distribution and diet composition of fish over the course of a day and a season. We will compare these observations with changes in the distribution of warm habitat – recorded by i-button temperature loggers – to assess the ability of coho to integrate across shifts in resource availability. We aim to document the frequency of resource tracking in juvenile coho during this early summer period. The results have implications for understanding the importance of environmental complexity to endangered salmon populations and associated species in systems where humans have homogenized floodplains.

River-dwelling organisms inhabit ecosystems characterized by an assortment of habitats that vary in their nutrient availability, temperature, flow, food resources, and risk to predation. Specific habitats rarely offer the optimal conditions for all of these variables so mobile organisms typically use habitat combinations that offer complementary risks and benefits. I hypothesize that tributary junctions within river networks are particularly profitable for fish because they offer complementary resources across small spatial scales. To test this hypothesis, I conducted snorkel surveys during the heat of the day around nine tributaries divided equally among three spatial segments in a river system in Idaho. Each river segment displayed a varying degree of historically active wildfires and provides a mosaic of heterogeneity in riparian cover and nutrient inputs. Fish were counted downstream and upstream of tributary junctions to obtain a total density per stream reach area. Nitrogen and phosphorous concentrations of incoming tributary water were measured as a proxy of primary productivity in each environment. I also measured water temperature at tributary junctions to quantify potential temperature gradients for fish to use as a thermal refuge. My preliminary results suggest that fish tend to aggregate at the junctions of tributaries that are different in temperature and nutrient status from the main stem. As climate changes, it is important to understand how river networks provide prosperous options for fish. My work will hopefully contribute to efforts designed to prioritize river habitats for protection and restoration.

In the past decade, the importance of the kisspeptin system in reproductive development and its pivotal role in the regulation of the reproductive endocrine axis has become clear. The kisspeptin system has roles in the onset of puberty, the control and regulation of sex steroid production, and regulation of fertility and reproductive function. However, the exact functions of the fish kisspeptin system are not well understood, especially their potential local roles in the gonads. Thus, the goal of my study was to characterize the expression of the kisspeptin genes (kiss1, kiss2, and the receptors kiss1ra and kiss1rb) in the marine teleost Anoplopoma fimbria (sablefish), and explore their possible gonadal functions during sex differentiation (i.e. the formation of the ovaries versus testes) and subsequent gonadal development. Using several molecular techniques, including standard, semi-quantitative, and quantitative PCR, and in situ hybridization (ISH), I revealed that kiss2 and kiss1rb are the most highly expressed of the sablefish kisspeptin genes and both show sexually dimorphic expression in the gonads. Specifically, kiss2 shows significant increases in gonadal expression during ovarian development and the receptor, kiss1rb, exhibits a similar expression profile. Localization of these mRNAs within the sablefish ovary by ISH demonstrated that they are both highly expressed in the cytoplasm of oocytes. Thus, my results suggest that Kiss1rb is the putative receptor for Kiss2 and that Kiss2 plays a role locally in ovarian development, but not sex differentiation. In the future studies, I hope to determine the specific function of the gonadal kisspeptins. If kisspeptins do have a role in early ovarian development, this system could be important to future studies on reproductive dysfunction that occurs in captive female sablefish and some other fishes.

Harbor seals (Phoca vitulina) are the most abundant seal species in Washington State. Harbor seal mother-pup pairs are abundant during pupping season, which lasts from June until August in the inland waters of the San Juan Island region. Mother seals give birth to one pup per year, providing maternal care to pups for three to four weeks after their birth. Mother-pup pairs use haul-out sites for nursing, resting, and thermoregulation. Haul-out sites are less available during higher tides, which affects the number of seals present and the behaviors of harbor seal mother-pup pairs. Since the majority of nursing occurs on land and pups are not strong swimmers, haul-out sites are important to their survival. Our study focuses on the behavior of harbor seal mother-pup pairs at Yellow Island, a marine preserve located in the San Juan Channel. On the west side of the island are two rocky spits and several small islands that harbor seals use as haul-outs during low tides. During high tides, they may become submerged underwater. On 12-13, 15-17, and 19 August 2013, we conducted land-based, focal animal behavioral surveys at Yellow Island. We used these observational data to compare the frequency of types of behavior with tide height and group size. In our study, tide height and group size function as proxies for haul-out site space availability. The results indicated that vigilance, nursing, bonding, swimming, and aggression show apparent trends when compared with tide height and that vigilance, loafing, and aggression show apparent trends when compared with group size. Behavioral research allows understanding of population dynamics and survival. Harbor seals populations in the San Juan Islands are healthy, but in other areas they are not. Understanding how harbor seals function in a healthy population may help with conservation of the species in other areas.

Lontra canadensis, more commonly known as the North American river otter, is a resident in many riparian and coastal ecosystems across the continent. The behaviors of mainland populations – the inhabitants of freshwater lakes and rivers – have been well documented and studied over the years. The impact of tides on coastal and estuarine populations, however, is still largely unknown. Therefore in 2012, members of the Ocean Research College Academy, a dual enrollment program run through Everett Community College, began studying otters in Possession Sound. Preliminary diet analysis of scats retrieved from local latrine sites revealed target prey consisting of mostly saltwater species. Due to the high metabolic rate of otters necessitating large daily food intake and prey availability in estuaries being driven by tidal cycles, it was then hypothesized a correlation existed between tides and the presence of otters in the sound. Specifically, it was predicted otters would be present at high salinity tides when the water chemistry could sustain their prey species. To test this, game cameras were installed at latrine sites on Jetty Island and the Hat Island ferry dock in Everett, Washington. Visits by otters were documented and time stamped, with corresponding tide stages and heights recorded. The majority of visitations occurred at tide heights above 4 feet (81% of visits) with considerably fewer camera captures during low salinity tides. Further research is currently being done into the possible impacts of other local factors on river otter behavior, including spring-neap tidal cycles and river discharge.

 North American river otter (Lontra canadensis) populations are difficult to assess by means such as live-capture; however, non-invasive fecal sampling has become a viable way to assess many aspects of river otter ecology including diet and genetics. L. canadensis uses specific locations called latrines to regularly defecate and scent mark. Fecal samples collected from latrine sites can be used for DNA analysis to distinguish unique individuals and evaluate genetic diversity in a population. Within Possession Sound, minimal research on the abundance and diversity of L. canadensis has been conducted. In fall of 2012, students at the Ocean Research College Academy (ORCA) became the first to study the species in this area. As of fall 2013, two latrine sites of L. canadensis in Possession Sound have been monitored using motion-sensing camera traps. Weekly checks for fresh scat and anal jellies are performed, with 153 samples collected so far. Diet is assessed by identifying prey remains present in feces. Currently, 27 scat samples have gone through DNA extraction, and Polymerase Chain Reaction (PCR) will be performed in the near future using the primers RIO-05, RIO-10, LUT-701, and LUT-801. DNA analysis results will provide information about population size, which is difficult to estimate using camera footage. It is expected that DNA analysis will identify a relatively small number of individuals, as the maximum number of otters simultaneously captured on camera footage is seven. With a small population size, we also expect some amount of genetic interrelatedness in the individuals identified through DNA analysis.

The marine pelagic zone extends from the open ocean basins to the continental shelves. It is a habitat for commercially important wild fish stocks and lesser known deep sea species. Both are crucial to oceanic ecosystems but poorly understood on an ecological level. Current fishery models are specific to harvested species and fail to capture the historical population collapses that occur periodically. The California sardine fishery collapse in 1949 instigated the formation of the California Cooperative Fisheries Investigations (CalCOFI), a coalition of organizations that conducts oceanographic cruises in the Southern California Current. The resulting 65 year time series of hydrographic and fish larva data represents an opportunity to observe and analyze the interactions between different fish species and their environment. This study uses first principles and the CalCOFI data to construct spatially averaged time-dependent population models parametrized for the environmental variables of temperature and dissolved oxygen. These models show bifurcations where variations in environmental parameters lead to extreme fluctuations in larval populations. In the current climate these critical parameter values are only reached under the influence of periodic events such as the Pacific Decadal Oscillation. Future climate projections indicate that environmental parameters will reach critical values over seasonal cycles. This may lead to long term changes in fish species distributions and the structure of globally important ecosystems. These considerations underscore the importance of continued observations and modeling research in the world’s oceans. Both are necessary to understand historical fishery collapses and to prepare for changes in the future climate.