Robert K. Cowen's research while affiliated with Oregon State University and other places

Publications (158)

Article
Doliolids are common gelatinous grazers in marine ecosystems around the world and likely influence carbon cycling due to their large population sizes with high growth and excretion rates. Aggregations or blooms of these organisms occur frequently, but they are difficult to measure or predict because doliolids are fragile, under sampled with convent...
Preprint
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Doliolids are common gelatinous grazers in marine ecosystems around the world and likely influence carbon cycling due to their large population sizes and high growth and excretion rates. Aggregations or blooms of these organisms occur frequently, but they are difficult to measure or predict because doliolids are fragile, under sampled with conventi...
Article
Full-text available
As the basis of oceanic food webs and a key component of the biological carbon pump, planktonic organisms play major roles in the oceans. Their study benefited from the development of in situ imaging instruments, which provide higher spatio-temporal resolution than previous tools. But these instruments collect huge quantities of images, the vast ma...
Article
Blooms of the colonial pelagic tunicate Pyrosoma atlanticum in 2014–2018 followed a marine heatwave in the eastern Pacific Ocean. Pyrosome blooms could alter pelagic food webs of the northern California Current (NCC) by accelerating the biological pump via active transport, fecal pellet production and mortality events. Although aggregations of P. a...
Article
Despite the ecological importance of microscale (0.01–1 meter) and fine-scale (1 to hundreds of meters) plankton patchiness, the dimensions and taxonomic identity of patches in the ocean are nearly unknown. We used underwater imaging to identify the position, horizontal length scale, and density of taxa-specific patches of 32 million organisms repr...
Article
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The distribution of plankton in the ocean is patchy across a wide range of spatial and temporal scales. One type of oceanographic feature that exemplifies this patchiness is a ‘thin layer’. Thin layers are subsurface aggregations of plankton that range in vertical thickness from centimeters to a few meters, which may extend horizontally for kilomet...
Article
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a Cnidarian jellyfish can be dominant players in the food webs of highly productive Eastern Boundary Currents (EBC). However, the trophic role of inconspicuous hydromedusae in EBCs has traditionally been overlooked. We collected mesozooplankton from five stations along two cross-shelf transects in the Northern California Current (NCC) during winter...
Article
Our knowledge of zooplankton in proximity to benthic marine habitats is hampered by challenges sampling near complex substrates. To address this, we deployed light traps near the benthos of four depth-specific coral reef ecosystems to measure nocturnal zooplankton abundance and assemblage composition. Replicate light traps at shallow shelf (SS10, <...
Article
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Restricted to low-productivity environments near their thermal maxima, larval tunas may be threatened by warming global temperatures, yet our understanding of how they are constrained is limited. We examined blackfin tuna (Thunnus atlanticus, presumptive) diet and growth in the context of their prey and predators in the Straits of Florida in 2 year...
Article
River plumes discharging into continental shelf waters have the potential to influence the distributions, predator-prey relationships, and thus survival of nearshore marine fish larvae, but few studies have been able to characterize the plume environment at sufficiently fine scales to resolve the underlying mechanisms. We used a high-resolution pla...
Article
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Tidally controlled river plumes form distinct frontal boundaries that can alter the spatial distributions of larval fishes and their planktonic prey and predators. Variable in nature, they may expose larval fishes to different trophic environments over small spatio-temporal scales, with unknown consequences for survival and recruitment. In the nort...
Article
Freshwater input into nearshore continental shelf waters from coastal river-estuarine plumes can greatly alter the physical and trophic environments experienced by fish larvae. However, the biological consequences of plume encounter on larval fish survival remain equivocal, largely due to the extreme variability of these systems but also because tr...
Article
The Northern California Current (NCC) is a complex, dynamic system experiencing distinctly different levels of upwelling and downwelling, ranging from intermittent upwelling in summer to downwelling in winter. In recent years, warm water anomalies along the Oregon coast have had significant effects on coastal plankton assemblages. To resolve some o...
Article
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Among marine organisms, gelatinous zooplankton (GZ; cnidarians, ctenophores, and pelagic tunicates) are unique in their energetic efficiency, as the gelatinous body plan allows them to process and assimilate high proportions of oceanic carbon. Upon death, their body shape facilitates rapid sinking through the water column, resulting in carcass depo...
Article
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Although plankton thin layers have been described and modeled in a variety of environments, the physical structure surrounding the layer, associated biological rates, and distributions of multiple trophic levels are rarely examined simultaneously. Similar combinations of measurements, such as growth, mortality, and spatial relationships among plank...
Article
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Eddies can enhance primary as well as secondary production, creating a diverse meso- and sub-mesoscale seascape at the eddy front which can affect the aggregation of plankton and particles. Due to the coarse resolution provided by sampling with plankton nets, our knowledge of plankton distributions at these edges is limited. We used a towed, undula...
Poster
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Larval fishes generally experience up to 99% mortality due to starvation and predation, hence finding prey is of high importance to their survival. The presence of other abundant predators such as hydromedusan jellyfish, might mean that these larval fishes must compete for food. Competition could lead to lower larval fish survival rates, but these...
Article
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Invasion of the western Atlantic Ocean, Caribbean Sea, and Gulf of Mexico by the Indo-Pacific lionfish, Pterois volitans/miles (Scopaenidae), has caused well-documented critical changes to coral reef ecosystems throughout the region. Most efforts to quantify these changes have focused on the charismatic adult stage; much less is known about the pel...
Chapter
Mesophotic coral ecosystems (MCEs) have the potential to supply larvae to help sustain spatially discrete shallow-reef populations (Deep Reef Refugia Hypothesis); however, for this to be viable, mesophotic populations must be ecologically connected to shallow-reef populations. Three primary criteria for successful connectivity are: (1) robust popul...
Article
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In this paper we review the technologies available to make globally quantitative observations of particles in general-and plankton in particular-in the world oceans, and for sizes varying from sub-microns to centimeters. Some of these technologies have been available for years while others have only recently emerged. Use of these technologies is cr...
Article
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Prey availability and predation pressure are thought to be key constraints on larval growth, especially in low-productivity, subtropical environments. Yet, measuring their effects on larval fishes has been challenging, given the dynamic biophysical drivers of plankton distributions and small scales of interactions. We integrated fine-scale net tows...
Article
The rise of in situ plankton imaging systems, particularly high‐volume imagers such as the In Situ Ichthyoplankton Imaging System, has increased the need for fast processing and accurate classification tools that can identify a high diversity of organisms and nonliving particles of biological origin. Previous methods for automated classification ha...
Poster
Full-text available
Introduction Zooplankton are morphologically diverse, encompassing a body composition continuum from fragile gelatinous animals to hard-bodied crustaceans, and serve as an important trophic link between primary production and fisheries. They have a variety of complex behaviors, including diel vertical migrations (DVMs), that can alter their exposur...
Article
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Coastal river-dominated oceans are physically complex, biologically productive, and intimately connected to human socioeconomic activity. The Deepwater Horizon blowout and subsequent advection of oil into coastal waters of the northern Gulf of Mexico (nGOM) highlighted the complex linkages among oceanographic processes within this river-dominated s...
Article
Pelagia noctiluca is a venomous, globally distributed holoplanktonic scyphomedusa that periodically forms aggregations in coastal environments, yet little is known about its ecology and behaviour in the northern Gulf of Mexico (nGOM). Using a high resolution plankton imaging system, we describe the patch characteristics of Pelagia medusae in relati...
Article
Lobster phyllosoma are known to associate with large cnidarian medusae; however, direct quantitative observations are difficult because gelatinous zooplankton are extremely fragile, and the phyllosoma easily detach from their host when sampled by plankton nets. We provide the first large scale quantitative information of the distribution of this as...
Article
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Ocean acidification and other environmental changes pose an ecological challenge to marine organisms globally. Although the youngest life stages of these organism are likely to be most affected, a limited number of studies of larval fishes have investigated the effects of combined stressors. We conducted two experiments on larval cobia (Rachycentro...
Article
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Big data " are becoming common in biological oceanography with the advent of sampling technologies that can generate multiple, high-frequency data streams. Given the need for " big " data in ocean health assessments and ecosystem management, identifying and implementing robust, and efficient processing approaches is a challenge for marine scientist...
Article
Benthic marine populations are often replenished by a combination of larvae from local and distant sources. To promote retention of locally spawned larvae in strong, unidirectional boundary current systems, benthic marine organisms must utilize biophysical mechanisms to minimize advective loss. We examined patterns in larval fish abundance, age dis...
Article
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Marine teleost fishes often experience over 99% mortality in the early life stages (eggs and larvae), yet larval survival is essential to population sustainability. Marine fish larvae from a wide range of families display elaborate, delicate features that bear little resemblance to adult forms and hinder their swimming escape ability by increasing...
Article
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Significance Quantifying connectivity among geographically separated subpopulations is necessary for successful management and conservation of marine resources, and a mechanistic understanding of growth and mortality during the pelagic larval stage is essential for obtaining accurate predictions of dispersal and population replenishment. Our findin...
Article
Plankton patch dynamics strongly influences rates of trophic transfer and many ecological processes, yet patchiness is poorly described, especially on fine-scales (cm to 10s of m). We deployed the In Situ Ichthyoplankton Imaging System beneath the Mississippi River plume to measure horizontal distributions of zooplankton across three depth zones (1...
Article
Imaging systems were developed to explore the fine scale distributions of plankton (<10 m), but they generate huge datasets that are still a challenge to handle rapidly and accurately. So far, imaged organisms have been either classified manually or pre-classified by a computer program and later verified by human operators. In this paper, we post-p...
Poster
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Marine snow is a ubiquitous yet morphologically and compositionally diverse constituent of the water column that plays a key role in the carbon cycle. Under certain physical circumstances, marine snow can aggregate and form thin layers, potentially serving as “trophic hotspots” of increased grazing activity. If oil is present, then marine snow thin...
Poster
Full-text available
Poster presented at the Jellyfish Bloom Symposium about a particular species of scyphomedusa aggregating on fine horizontal and vertical scales in relation to salinity
Data
Data presented here are subset of a larger plankton imagery data set collected in the subtropical Straits of Florida from 2014-05-28 to 2014-06-14. Imagery data were collected using the In Situ Ichthyoplankton Imaging System (ISIIS-2) as part of a NSF-funded project to assess the biophysical drivers affecting fine-scale interactions between larval...
Presentation
Current knowledge of zooplankton distribution at very fine scale (~1 m) is limited, as even the most advanced nets integrate over 10s of m of depth and 100s of m horizontally. Yet, this fine scale is the one relevant for biological interactions such as predation or gregarious behaviour. New imaging tools, like the In Situ Ichthyoplankton Imaging Sy...
Article
Full-text available
Like most benthic marine organisms, coral reef fishes produce larvae that traverse open ocean waters before settling and metamorphosing into juveniles. Where larvae are transported and how they survive is a central question in marine and fisheries ecology. While there is increasing success in modelling potential larval trajectories, our knowledge o...
Article
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In the past 100 years since the birth of fisheries oceanography, researchon the early life history of fishes, particularly the larval stage, has been extensive, and much progress has been made in identifying the mechanisms by which factors suchas feeding success, predation, or dispersal can influence larval survival. However, in recent years, the s...
Article
Ocean fronts represent productive regions of the ocean, but predator-prey interactions within these features are poorly understood partially due to the coarse-scale and biases of net-based sampling methods. We used the In Situ Ichthyoplankton Imaging System (ISIIS) to sample across a front near the Georges Bank shelf edge on two separate sampling d...
Article
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Negative impacts of CO2-induced ocean acidification on marine organisms have proven to be variable both among and within taxa. For fishes, inconsistency confounds our ability to draw conclusions that apply across taxonomic groups and highlights the limitations of a nascent field with a narrow scope of study species. Here, we present data from a ser...
Article
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Mesoscale fronts occur frequently in many coastal areas and often are sites of elevated productivity; however, knowledge of the fine-scale distribution of zooplankton at these fronts is lacking, particularly within the mid-trophic levels. Furthermore, small (<13 cm) gelatinous zooplankton are ubiquitous, but are under-studied, and their abundances...
Poster
Full-text available
Current knowledge of larval fish distribution in the fine-scale (<10m) is limited, as even the most advanced nets integrate over 10s of m of depth and 100s of m horizontally. Yet, this fine-scale is the one relevant for biological interactions such as predation or gregarious behaviour. New imaging tools, like the In Situ Ichthyoplankton Imaging Sys...
Article
Full-text available
Thin layers of phytoplankton are well documented, common features in coastal areas globally, but little is known about the relationships of these layers to higher trophic levels. We deployed the In Situ Ichthyoplankton Imaging System (ISIIS) to simultaneously quantify the three trophic levels of plankton, including phytoplankton, primary consumers...
Article
Full-text available
Ocean acidification affects a wide diversity of marine organisms and is of particular concern for vulnerable larval stages critical to population replenishment and connectivity. Whereas it is well known that ocean acidification will negatively affect a range of calcareous taxa, the study of fishes is more limited in both depth of understanding and...
Article
Currently, ocean acidification is occurring at a faster rate than at any time in the last 300 million years, posing an ecological challenge to marine organisms globally. There is a critical need to understand the effects of acidification on the vulnerable larval stages of marine fishes, as there is potential for large ecological and economic impact...
Article
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Selective mortality during the early life stages in marine organisms can affect the magnitude and composition of recruitment, yet these processes have not been examined in economically important predatory coral reef fishes. Utilizing 3 different stage-specific sampling techniques (shipboard plankton tows, larval light traps, juvenile surveys/seines...
Article
The purpose of this study was to further our understanding of the role of the coastal physical environment as a dynamic and constantly evolving habitat for plankton. Over a 3-wk period in the summer of 2010, an array of moorings were deployed and shipboard and autonomous underwater vehicle (AUV) surveys were conducted in order to investigate the as...
Article
The Swiss mathematician Leonhard Euler (1707-83) derived the formulations for describing fluid motion by either measuring the properties of the fluid at a fixed point overtime or alternatively following the trajectory of a parcel of fluid as it is carried with the flow. The first of these is known as the Eulerian description of the flow, while the...
Article
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Plankton and larval fish sampling programs often are limited by a balance between sampling frequency (for precision) and costs. Advancements in sampling techniques hold the potential to add considerable efficiency and, therefore, add sampling frequency to improve precision. We compare a newly developed plankton imaging system, In Situ Ichthyoplankt...
Article
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1] We sampled a front detected by SST gradient, ocean color imagery, and a Spray glider south of San Nicolas Island in the Southern California Bight between 14 and 18 October 2010. We sampled the front with an unusually extensive array of instrumentation, including the Continuous Underway Fish Egg Sampler (CUFES), the undulating In Situ Ichthyoplan...
Article
Little is known about the seasonality and distribution of grouper larvae (Serranidae: Epinephelini) in the Gulf of Mexico and Atlantic Ocean off the coast of the southeast United States. Grouper larvae were collected from a transect across the Straits of Florida in 2003 and 2004 and during the Southeast Area Monitoring and Assessment Program spring...
Article
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The great barracuda (Sphyraena barracuda) is a widespread, ecologically and socioeconomically important coastal fish, yet very little is known about its larvae. We examined spawning and larval ecology of Western Atlantic sphyraenids using monthly ichthyoplankton samples collected over 2years along a transect spanning the east–west axis of the Strai...
Article
The goals of this study were to measure vertical distributions of pelagic coral reef fish larvae, identify significant vertical migrations, and estimate the effects of vertical migrations between depths with different ambient currents on larval transport in the Straits of Florida. Spring, summer, and fall time-series of plankton net tows were condu...
Article
Aim To identify connectivity patterns among coral reefs of the Indo-West Pacific. Projecting connectivity forward in time provides a framework for studying long-term source–sink dynamics in the region, and makes it possible to evaluate the manner in which migration shapes population genetic structure at regional scales. This information is essentia...
Article
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Behavior such as ontogenetic vertical migration (OVM) limits the transport of marine larvae with short pelagic larval durations (PLDs), but its effect on the supposed long-distance dispersal of larvae with long PLDs is unknown. We conducted laboratory tests of ontogenetic change in larval phototaxis and examined size-specific patterns of larval dis...
Article
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Three seasons of vertically stratified ichthyoplankton sampling at the edge of the Florida Current revealed consistent accumulations of some coral reef fish larvae under taxon-specific environmental conditions. Environmental variability ranging from predictable (seasonal differences in temperature, diel changes in light, and vertical gradients in m...
Article
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The identities of early life stages of groupers worldwide are virtually unknown. Current identification strategies rely on characters not yet developed in small larvae ( References: 34 references open in new window Opening the references page in a new window requires javascript to be enabled in your browser. Articles that cite this article? Documen...
Article
Critical gaps in our understanding of the distributions, interactions, life histories and preferred habitats of large and medium-size pelagic fishes severely constrain the implementation of ecosystem-based, spatially structured fisheries management approaches. In particular, spawning distributions and the environmental characteristics associated wi...
Article
Monthly plankton sampling across the Straits of Florida (SOF) allowed for a thorough investigation of the feeding ecologies of four taxa of larval tunas (family Scombridae, tribe Thunnini) and the horizontal and vertical distributions of tuna larvae and their dominant prey. Before piscivory, Thunnus spp. larvae had a mixed diet of crustaceans and a...
Article
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Atlantic blue marlin (Makaira nigricans) and sailfish (Istiophorus platypterus) larvae were collected from 10monthly cruises (June–October 2003 and 2004) across the Straits of Florida to test (1) whether growth differed between the more productive western region near the Florida shelf, and the less productive eastern region toward the Bahamas, and...
Article
A matrix-based projection model is used in conjunction with the results of a coupled bio-physical dispersal model to examine the spread of alleles through subdivided populations over time, and the associated development of genetic structural patterns. Applying this approach, it becomes possible to quantitatively evaluate the contribution of spatial...
Article
Age-based analysis of the stoplight parrotfish Sparisoma viride was used to examine whether observed differences in their abundance and size structure among reefs in a cross-shelf portion of the upper Florida Keys could be explained by variation in demographic rates. Annual and daily sagittal otolith increments were enumerated for 176 individuals c...
Article
Full-text available
Much of the uncertainty in managing highly migratory pelagic species results from the scarcity of fisheries-independent data relevant to determining long-term trends in abundance, migratory movements, and the relative importance of different spawning grounds. To address these issues, we used an ichthyoplankton-based method to quantify the overall l...
Article
Fronts and eddies are widely hypothesized to be critical spawning habitat for large pelagic fishes, due to increased larval and/or adult feeding opportunities at these features. We examined sailfish (Istiophorus platypterus) spawning around a cyclonic, submesoscale (∼13 × 7 km) Florida Current frontal eddy. The temporal progression of eddy dynamics...
Article
The transport of larval coral reef fishes to juvenile habitat inherently requires that they survive the planktonic journey; however, the processes governing survival — particularly those related to feeding — are not well known. Monthly sampling across the Straits of Florida allowed for analyses of the diets and diet variability of several co-occurr...
Article
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Genetic population structure throughout the Caribbean Basin for one of the most common and widespread reef fish species, the bicolour damselfish Stegastes partitus was examined using microsatellite DNA markers. Spatial autocorrelation analysis showed a significant positive correlation between genetic and geographic distance (isolation by distance)...
Presentation
Through its interaction with vertical current shears, the vertical migration of planktonic organisms influences the direction and speed at which they are transported. This interaction is thought to be critical because diel or tidal migration cycles are almost universal. For larvae however, the longer-term migration patterns, throughout ontogeny, ar...
Article
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Connectivity, or the exchange of individuals among marine populations, is a central topic in marine ecology. For most benthic marine species with complex life cycles, this exchange occurs primarily during the pelagic larval stage. The small size of larvae coupled with the vast and complex fluid environment they occupy hamper our ability to quantify...
Article
While metapopulation research with hypothetical dispersal matrices has shown how the scales of larval dispersal, transport processes, local recruitment, and temporal and spatial variability in dispersal influence population persistence, the pattern of demographic connectivity produced by larval dispersal is still a key uncertainty. To address this...