Aaron W. E. Galloway

University of Oregon | UO · Oregon Institute of Marine Biology

Coastal-estuarine systems are among the most productive marine ecosystems and their special role in producing harvestable fish and shellfish has been attributed to high primary production fueled by nutrient runoff from land and efficient trophic transfer. Here we ask if phytoplankton species composition and their food quality based on the percentag...

Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer 'growing seasons'. We executed the first global quantitative synthesis on under-ice lake ecology, including...

Essential fatty acids (EFA), which are primarily generated by phytoplankton, limit growth and reproduction in diverse heterotrophs. The biochemical composition of phytoplankton is well-known to be governed both by phylogeny and environmental conditions. Nutrients, light, salinity, and temperature all affect both phytoplankton growth and fatty acid...

Herbivorous primary consumers are a key intermediate trophic linkage between primary production from microalgae, macrophytes, and vascular plants to higher-level consumers. Fatty acid (FA) biomarkers are useful for evaluating trophic interactions in aquatic ecosystems because of clear phylogenetic separation of algal group FA signatures. We used a...

Coastal kelp forests are important sources of primary productivity and provide essential habitat and ecosystem services. In many areas around the world, the formation and persistence of urchin barrens threatens kelp forest ecosystems. Over the past several decades, restoration efforts have emerged aiming to increase the abundance of foundation spec...

Human‐caused global change produces biotic and abiotic conditions that increase the uncertainty and risk of failure of restoration efforts. A focus of managing for resiliency, that is, the ability of the system to respond to disturbance, has the potential to reduce this uncertainty and risk. However, identifying what drives resiliency might depend...

Many marine benthic invertebrates have a pelagic life stage, during which larvae need to accumulate enough reserves to complete metamorphosis to a settled benthic juvenile. Currently, very little is known about how ocean conditions affect quality of the larvae. We studied this for three settlement seasons (2017–2019) by collecting returning Dungene...

Ecosystem function is maintained in part by direct species interactions, but indirect interactions and non‐consumptive effects may be of equal ecological importance. Along the west coast of North America, the recent population collapse of the predatory sunflower sea star Pycnopodia helianthoides has been implicated in the proliferation of the purpl...

The Western Antarctic Peninsula supports a diverse assemblage of > 100 described macroalgal species that contribute to the base of coastal food webs, but their contribution to local nearshore food webs is still uncertain across larger spatial scales. The analysis of biomarkers, specifically fatty acids and stable isotopes, offers a tool to clarify...

Rhizocephalan barnacles are parasites of crustaceans that are known for dramatic effects on hosts, including parasitic castration, feminization, molt inhibition, and the facilitation of epibiosis. Most research on rhizocephalans has focused on carcinized hosts, with relatively little research directed to shrimp hosts that may experience distinct co...

Fleshy macroalgae dominate the hard bottom, shallow waters along the Western Antarctic Peninsula (WAP). Although there are numerous reports on their ecology, geographic distribution, and to a lesser extent, vertical (depth) distribution in the northern portions of the WAP, much less is known farther south along the central portion of the WAP. Here...

A proposal for the Margaret A. Davidson Fellowship to determine European green crab impacts on the South Slough estuary in Coos Bay, Oregon.

Macroalgal forests dominate shallow hard bottom areas along the northern portion of the Western Antarctic Peninsula (WAP). Macroalgal biomass and diversity are known to be dramatically lower in the southern WAP and at similar latitudes around Antarctica, but few reports detail the distributions of macroalgae or associated macroinvertebrates in the...

Juvenile Dungeness crab foraging behavior and lipid composition is altered more by food quantity than seawater pH in a multi-stressor experiment A B S T R A C T Increases in atmospheric, anthropogenic carbon are driving reductions in seawater pH, a process referred to as ocean acidification. Reduced seawater pH can influence behavior of marine anim...

Increases in atmospheric, anthropogenic carbon are driving reductions in seawater pH, a process referred to as ocean acidification. Reduced seawater pH can influence behavior of marine animals, but little is currently known about how juvenile crustaceans will respond. We conducted lab experiments to improve our understanding of the consequences of...

The recent collapse of predatory sunflower sea stars ( Pycnopodia helianthoides ) owing to sea star wasting disease (SSWD) is hypothesized to have contributed to proliferation of sea urchin barrens and losses of kelp forests on the North American west coast. We used experiments and a model to test whether restored Pycnopodia populations may help re...

Sewage released from lakeside development can reshape ecological communities. Nearshore periphyton can rapidly assimilate sewage‐associated nutrients, leading to increases of filamentous algal abundance, thus altering both food abundance and quality for grazers. In Lake Baikal, a large, ultra‐oligotrophic, remote lake in Siberia, filamentous algal...

Sewage released from lakeside development can introduce nutrients and micropollutants that can restructure aquatic ecosystems. Lake Baikal, the world's most ancient, biodiverse, and voluminous freshwater lake, has been experiencing localized sewage pollution from lakeside settlements. Nearby increasing filamentous algal abundance suggests benthic c...

Intraspecific variation in external and internal pigmentation is common among fishes and explained by a variety of biological and ecological factors. Blue-colored flesh in fishes is relatively rare but has been documented in some species of the sculpin, greenling, and perch families. Diet, starvation, photoprotection, and camouflage have all been s...

Indigenous societies worldwide recognize people as inherent parts of ecosystems (e.g., Council of the Haida Nation 2007, Brown and Brown 2009). Indigenous governance systems are based on relationships, knowledge, and practices that reflect a deep history of interdependence between people and the places they live, sustaining biological and cultural...

Surf zone hydrodynamics influences the delivery of coastal phytoplankton and detritus food subsidies to shore. Variation in surf zone hydrodynamics can cause phytoplankton concentrations to be higher at dissipative than reflective surf zones, altering both the quantity and quality of food for intertidal suspension-feeders. To assess if surf zone-de...

This research combined submersible and scuba observations of red sea urchins (Mesocentrotus franciscanus) in the Salish Sea to explore: 1. Full depth range. We confirmed the prediction that red urchins exceed known depth range of 125m when subtrate and drift kelp is present. 2. Drift algae (detritus) availability to urchins throughout their depth...

The non-indigenous colonial tunicate Didemnum vexillum plagues many shellfish aquaculture operations around the world by smothering crop and gear and displacing juvenile bivalves. There are two populations of D. vexillum in Oregon, but little is known regarding their spatial extent, seasonal dynamics, annual variability, reproductive biology, or ec...

The global distribution of primary production and consumption by humans (fisheries) is well-documented, but we have no map linking the central ecological process of consumption within food webs to temperature and other ecological drivers. Using standardized assays that span 105° of latitude on four continents, we show that rates of bait consumption...

For many historical and contemporary experimental studies in marine biology, seawater carbonate chemistry remains a ghost factor, an uncontrolled, unmeasured, and often dynamic variable affecting experimental organisms or the treatments to which investigators subject them. We highlight how environmental variability, such as seasonal upwelling and b...

During 2016-2018, unprecedented aggregations of the colonial pelagic tunicate Pyrosoma atlanticum were observed in the Northern California Current (NCC). Pyrosomes are common in tropical and sub-tropical ocean waters, but little is known about their abundance, distribution, and trophic ecology in mid-latitude systems. To assess these factors, pyros...

Determining the transfer and transformation of organic matter in food webs is a fundamental challenge that has implications for sustainable management of ecosystems. Fatty acids (FA) offer a potential approach for resolving complex diet mixtures of organisms because they provide a suite of molecular tracers. Yet, uncertainties in the degree of thei...

Dungeness crabs ( Metacarcinus magister ) are ecologically and economically important in the coastal Northeast Pacific, yet relatively little is currently known about their feeding behaviour in the wild or their natural diet. Trophic biomarkers, such as fatty acids (FA), can be used to reveal trophic interactions. We used two feeding experiments to...

Fatty acids are commonly used as biomarkers for making inferences about trophic relationships in aquatic and soil food webs. However, researchers are often unaware of the physiological constraints within organisms on the trophic transfer and modification of dietary biomarkers in consumers. Fatty acids are bioactive molecules, which have diverse str...

Recent warnings from scientists suggest there is limited time to enact policies to avert wide‐ranging ecological and social damage from climate change. In the United States, discussions about comprehensive national policies to avert climate change have begun, with “Green New Deal” proposals and climate plans put forth by members of Congress and pre...

The shallow benthos along the western Antarctic Peninsula supports brown macroalgal forests with dense amphipod assemblages, commonly including Gondogeneia antarctica (Amsler et al. 2014). Gondogeneia antarctica and most other amphipods are chemically deterred from consuming the macroalgae (Amsler et al. 2014). They primarily consume diatoms, other...

Negative consequences of parasites and disease on hosts are usually better understood than their multifaceted ecosystem effects. The pathogen Labyrinthula zosterae (Lz) causes eelgrass wasting disease but has relatives that produce large quantities of nutritionally valuable long-chain polyunsaturated fatty acids (LCPUFA) such as docosahexaenoic aci...

Climate change and land-use practices can enhance lake eutrophication and browning, which influence phytoplankton composition by decreasing the availability of food high in nutritional quality (algae) and increasing the abundance of low-quality food (terrestrial detritus, bacteria) for herbivorous zooplankton. Nutritionally valuable algae for zoopl...

Algal subsidies are important to basal consumers of the deep benthos where there is little to no primary productivity. Algal detritus such as pieces of kelp that sink into deep habitats can be an important direct nutritional subsidy, but sea urchin feces may provide an additional, indirect energetic link from shallow-water macroalgae to benthic com...

The movement of trophic resources between and among ecosystems, referred to as cross‐ecosystem subsidies, is a common phenomenon. In the marine environment, both adjacent and distant ecosystems are connected by oceanographic forces that transport nutrients, organisms, and other materials. Kelp forest ecosystems are one example of an open marine sys...

The sea urchin Strongylocentrotus purpuratus (order Camarodonta, family Strongylocentrotidae) can be found dominating low intertidal pool biomass on the southern coast of Oregon, USA. In this case study, three adult sea urchins were collected from their shared intertidal pool, and the bacteriome of their pharynx, gut tissue, and gut digesta, includ...

Ancient lakes are among the best archivists of past environmental change, having experienced more than one full glacial cycle, a wide range of climatic conditions, tectonic events, and long association with human settlements. These lakes not only record long histories of environmental variation and human activity in their sediments, but also harbor...

Sea urchins are ecosystem engineers of nearshore benthic communities because of their influence on the abundance and distribution of macroalgal species. Urchins are notoriously inefficient in assimilation of their macroalgal diets, so their fecal production can provide a nutritional subsidy to benthic consumers that cannot capture and handle large...

Many freshwater systems receive substantial inputs of terrestrial organic matter. Terrestrially derived dissolved organic carbon (t‐DOC) inputs can modify light availability, the spatial distribution of primary production, heat, and oxygen in aquatic systems, as well as inorganic nutrient bioavailability. It is also well‐established that some terre...

Aquatic and riparian habitats increasingly are affected by anthropogenic stressors, but the effects of these stressors on the nutritional quality of primary producers are often unknown. We compared essential fatty acids (EFAs) in the phytobenthos (benthic algae) growing on different substrate types (bricks, clay tiles, rocks, macrophytes, and sedim...

Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer "growing seasons." We executed the first global quantitative synthesis on under-ice lake ecology, including...

Stable isotope (SI) mixing models are one of the most common approaches used to infer resource pathways in consumers. However, SI-based analyses are often underdetermined, and consumer SI fractionation is often unknown. The use of fatty acid (FA) biomarkers in mixing models offers an alternative approach that can resolve the underdetermined constra...

Freshwater food webs can be partly supported by terrestrial primary production, often deriving from plant litter of surrounding catchment vegetation. Although consisting mainly of poorly bioavailable lignin, with low protein and lipid content, the carbohydrates from fallen tree leaves and shoreline vegetation may be utilized by aquatic consumers. H...

Rapid changes, including warming and freshening, are occurring in coastal marine ecosystems worldwide. These environmental changes have the potential to alter ecosystem energetics by influencing availability of food sources and organism physiology. We investigated the influence of oceanographic variability on food availability and quality to benthi...

Biomass from nearshore primary producers can be an important subsidy to both pelagic and benthic communities, which are disconnected in space from sources of production. We examine the role of this macrophyte biomass in two habitats (pelagic and nearshore benthic) in terms of both trophic support and spatial refugia. Experimental benthic “islands”...

We modified the stable isotope mixing model MixSIR to infer primary producer contributions to consumer diets based on their fatty acid composition. To parameterize the algorithm, we generated a ‘consumer-resource library’ of FA signatures of Daphnia fed different algal diets, using 34 feeding trials representing diverse phytoplankton lineages. This...

This is a 'living document' which attempts to provide some introduction to the use of fatty acids in aquatic sciences. Aaron Galloway wrote the initial draft and invited Mike Brett (a previous advisor and current collaborator) to add his perspectives. We both get a fair amount of email communication from people asking questions about getting starte...

Sea urchins are important ecosystem engineers in subtidal ecosystems worldwide, providing biogenic structure and altering nutrient dynamics through intensive grazing and drift algal capture. The current work evaluates red urchin (Strongylocentrotus franciscanus) density on fixed transects through time, individual displacement, and urchin-associated...

In Washington state, commercial culture of geoducks (Panopea generosa) involves large-scale out-planting of juveniles to intertidal habitats, and installation of PVC tubes and netting to exclude predators and increase early survival. Structures associated with this nascent aquaculture method are examined to determine whether they affect patterns of...

Marine bivalves are important ecosystem constituents and frequently support valuable fisheries. In many nearshore areas, human disturbance—including declining habitat and water quality—can affect the distribution and abundance of bivalve populations, and complicate ecosystem and fishery management assessments. Infaunal bivalves, in particular, are...

Marine bivalves are important ecosystem constituents and frequently support valuable fisheries. In many nearshore areas, human disturbance—including declining habitat and water quality—can affect the distribution and abundance of bivalve populations, and complicate ecosystem and fishery management assessments. Infaunal bivalves, in particular, are...

Long-term patterns and drivers of ecosystem structure may be misunderstood if knowledge of an ecosystem is derived primarily from a single season, a situation common in many temperate lakes where the role of winter has been less studied. In lakes, avoidance of winter research has been especially pronounced for those that experience winter ice, but...

The taxon specificity of fatty acid composition in algal classes suggests that fatty acids could be used as chemotaxonomic markers for phytoplankton composition. The applicability of phospholipid-derived fatty acids as chemotaxonomic markers for phytoplankton composition was evaluated by using a Bayesian fatty acid-based mixing model. Fatty acid pr...

Kelps in temperate marine ecosystems produce substantial detrital biomass that provides a carbon subsidy to consumers in neighboring habitats. After detachment, detrital kelp degrades and potentially changes in nutritional quality. Red sea urchins, Mesocentrotus franciscanus, are an abundant consumer of drift algae from the shallow subtidal to >100...

Suspended particulate organic matter (POM) is a primary food source for benthic and pelagic consumers in aquatic and marine ecosystems. POM is potentially composed of many sources, including phytoplankton, bacteria, zooplankton and macrophyte (seaweed and seagrass) and terrestrial detritus. The relative importance of these sources to POM consumers...

The zooplankton is a key link in the transfer of energy from primary producers up through aquatic food webs. Previous efforts to quantify the importance of basal resources to aquatic consumers have used stable isotopes ( SI ) and simple ternary models, including only ‘bulk’ phytoplankton, bacteria or terrestrial particulate organic matter (t‐ POM )...