Lutjanid snappers are ubiquitous at reef sites in the northern Gulf of Mexico (Gulf), but the deg... more Lutjanid snappers are ubiquitous at reef sites in the northern Gulf of Mexico (Gulf), but the degree of niche overlap and basal resource utilization is unknown for most species. Muscle tissue for stable isotope analysis was opportunistically sampled from red snapper (Lujanus campechanus), gray snapper (Lutjanus griseus), lane snapper (Lutjanus synagris), and vermilion snapper (Rhomboplites aurorubens) recreational catches across the northern Gulf. A Bayesian mixing model used to compare resource utilization indicated that Lutjanids occupy niches with varying degrees of overlap among regions but maintain a consistent hierarchy in isotopic composition. Scale shifts among regions were likely due to differences in riverine outflow, nitrogen fixation, and anoxic zones that alter prey abundance or isotopic δ15N ratios. All four Lutjanid species had high percent contributions from particulate organic matter and benthic microalgae with little contribution by macroalgae to any species in any...
The formation of fish spawning aggregations (FSAs) is an essential part of the life history of ma... more The formation of fish spawning aggregations (FSAs) is an essential part of the life history of many economically important fish species; however, their status are often poorly described in the literature either due to their occurrence in remote locations, during seasons with unsafe ocean conditions, or because they move on space and time scales that are difficult to predict and validate. Even in areas that are relatively accessible and heavily fished, such as southeast Florida, regionally relevant information describing FSA dynamics is generally absent from the literature and unaccounted for in existing management plans. We propose that this can be attributed to the fact that information is often held by stakeholders or found in unpublished manuscripts and reports. These sources are not widely disseminated and are therefore difficult to locate and integrate into fisheries management decisions. In this paper, we present a case study demonstrating the value of regional data syntheses ...
Ecosystem services are anthropocentric. They are the benefits that humans receive from the natura... more Ecosystem services are anthropocentric. They are the benefits that humans receive from the natural environment. Yet, do we really consider the potential impact on human well-being as we plan, execute, and monitor restoration and conservation projects? And if we are, is there a real connection between the biophysical structure, function, and processes to ecosystem services and then human well-being? There currently exists a significant opportunity in the Gulf of Mexico to change the way we conduct our "restoration" business. Ecosystem services can play a role in selection among project alternatives but more importantly it can help elucidate the benefits of restoration and be a measure of the "impact of investment" that is being made.
The pelagic Gulf of Mexico (GoM) is a complex system of dynamic physical oceanography (western bo... more The pelagic Gulf of Mexico (GoM) is a complex system of dynamic physical oceanography (western boundary current, mesoscale eddies), high biological diversity, and community integration via diel vertical migration and lateral advection. Humans also heavily utilize this system, including its deep-sea components, for resource extraction, shipping, tourism, and other commercial activity. This utilization has had impacts, some with disastrous consequences. The Deepwater Horizon oil spill (DWHOS) occurred at a depth of ∼1500 m (Macondo wellhead), creating a persistent and toxic mixture of hydrocarbons and dispersant in the deep-pelagic (water column below 200 m depth) habitat. In order to assess the impacts of the DWHOS on this habitat, two large-scale research programs, described herein, were designed and executed. These programs, ONSAP and DEEPEND, aimed to quantitatively characterize the oceanic ecosystem of the northern GoM and to establish a time-series with which natural and anthrop...
Observing multiple size classes of organisms, along with oceanographic properties and water mass ... more Observing multiple size classes of organisms, along with oceanographic properties and water mass origins, can improve our understanding of the drivers of aggregations, yet acquiring these measurements remains a fundamental challenge in biological oceanography. By deploying multiple biological sampling systems, from conventional bottle and net sampling to in situ imaging and acoustics, we describe the spatial patterns of different size classes of marine organisms (several microns to ∼10 cm) in relation to local and regional (m to km) physical oceanographic conditions on the Delaware continental shelf. The imaging and acoustic systems deployed included (in ascending order of target organism size) an imaging flow cytometer (CytoSense), a digital holographic imaging system (HOLOCAM), an In Situ Ichthyoplankton Imaging System (ISIIS, 2 cameras with different pixel resolutions), and multi-frequency acoustics (SIMRAD, 18 and 38 kHz). Spatial patterns generated by the different systems show...
Editorial on the Research Topic Deep Pelagic Ecosystem Dynamics in a Highly Impacted Water Column... more Editorial on the Research Topic Deep Pelagic Ecosystem Dynamics in a Highly Impacted Water Column: The Gulf of Mexico After Deepwater Horizon AIMS AND OBJECTIVES OF RESEARCH TOPIC The intermediate-sized midwater fauna (fishes, shrimps, and cephalopods; "micronekton" collectively) are dominant components of the pelagic ocean, which is by far the largest ecosystem type on Earth by several metrics (volume, organismal numbers, biomass, and productivity). Deeppelagic micronekton, those animals residing in the water column below 200 m depth during the day, are the direct link between plankton and oceanic top predators, and through the linked processes of feeding and daily vertical migration facilitate one of Earth's most important ecosystem services to humans, carbon sequestration. Despite increasing recognition of this importance, a disconnect exists between stewardship and human impact; only a miniscule fraction of the deeppelagic ocean has been studied in detail, while anthropogenic threats to that system are increasing rapidly. Perhaps nowhere on Earth is that dichotomy more demonstrable than the Gulf of Mexico (Gulf hereafter), a complex, high-diversity ecosystem under intense human usage and subjected to arguably the worst marine pollution event in human history. Assessment of the impacts of the Deepwater Horizon disaster to the deep-pelagic biota was impeded from the start by the lack of pre-event information, both in terms of baselines (faunal composition, abundance, and distribution) and in terms of understanding natural variability, against which impacts of anthropogenic disturbance could be detected and quantified. In this Research Topic, we present a description of three interlinked research programs (ONSAP, DEEPEND, and DEEPEND|RESTORE, described below) that began in 2010 and continue as of this writing. These programs were designed to investigate key aspects of the Gulf pelagic ecosystem, including its faunal structure, biophysical drivers of that structure, organismal and community ecology, natural variability, and potential resilience to disturbance. The contributed papers are grouped below by major themes, indicated in the conceptual model (Figure 1) of DEEPEND (Deep Pelagic Nekton Dynamics; www.deependconsortium.org), the largest of the three aforementioned research programs.
The ocean’s mesopelagic zone is largely uncharacterized despite its vital role in sustaining ocea... more The ocean’s mesopelagic zone is largely uncharacterized despite its vital role in sustaining ocean ecosystems. The composition, cycling, and fate of particle fields in the mesopelagic lacks an integrative multi-scale understanding of organism migration patterns, distribution, and diversity. This problem is addressed by combining complementary technologies with overlapping size spectra, including profiler mounted optical scattering sensors, profiler, and ship mounted acoustic devices, and a custom Unobtrusive Multi-Static Lidar Imager (UMSLI). This unique sensor suite can observe distributions of particles including organisms over a six order of magnitude dynamic size range, from microns to meters. Overlapping size ranges between different methods allows for cross-validation. This work focuses on the lidar imaging measurements and optical backscattering and attenuation, covering a combined particle size range of 0.1 mm to several cm. Particles at the small end of this range are sized...
Understanding the stress responses of sharks to recreational catch and release fishing has import... more Understanding the stress responses of sharks to recreational catch and release fishing has important management and conservation implications. The blacktip shark Carcharhinus limbatus is a popular recreational species targeted throughout the western, central and eastern Gulf of Mexico (Gulf) yet it is unclear what levels of physiological stress result from catch-release fishing practices with hook and line gear and if the stress levels result in post-release mortality. This study correlates physiological response to stress through blood chemistry analysis and examines post-release behaviour of adult blacktip sharks caught to determine post-release mortality rates. Release behaviour was determined by pop-up satellite archival transmitting (PSAT) tags that record temperature, depth and light level data. To quantify physiological stress levels, blood samples were collected from 52 blacktip sharks and a suite of metabolic and osmotic markers were measured. Thirty-six of those blacktip s...
Oceanic diel vertical migration (DVM) constitutes the daily movement of various mesopelagic organ... more Oceanic diel vertical migration (DVM) constitutes the daily movement of various mesopelagic organisms migrating vertically from depth to feed in shallower waters and return to deeper water during the day. Accurate classification of taxa that participate in DVM remains non-trivial, and there can be discrepancies between methods. DEEPEND consortium (www.deependconsortium.org) scientists have been characterizing the diversity and trophic structure of pelagic communities in the northern Gulf of Mexico (nGoM). Profiling has included scientific echosounders to provide accurate and quantitative estimates of organismal density and timing as well as quantitative net sampling of micronekton. The use of environmental DNA (eDNA) can detect uncultured microbial taxa and the remnants that larger organisms leave behind in the environment. eDNA offers the potential to increase understanding of the DVM and the organisms that participate. Here we used real-time shipboard echosounder data to direct the sampling of eDNA in seawater at various time-points during the ascending and descending DVM. This approach allowed the observation of shifts in eDNA profiles concurrent with the movement of organisms in the DVM as measured by acoustic sensors. Seawater eDNA was sequenced using a high-throughput metabarcoding approach. Additionally, fine-scale acoustic data using an autonomous multifrequency echosounder was collected simultaneously with the eDNA samples and changes in organism density in the water column were compared with changes in eDNA profiles. Our results show distinct shifts in eukaryotic taxa such as copepods, cnidarians, and tunicates, over short timeframes during the DVM. These shifts in eDNA track changes in the depth of sound scattering layers (SSLs) of organisms and the density of organisms around the CTD during eDNA sampling. Dominant taxa in eDNA samples were mostly smaller organisms that may be below the size limit for acoustic detection, while taxa such as teleost fish were much less abundant in eDNA data compared to acoustic data. Overall, these data suggest that eDNA, may be a powerful new tool for understanding the dynamics and composition of the DVM, yet challenges remain to reconcile differences among sampling methodologies.
Proceedings of the Royal Society B: Biological Sciences, 2020
Linking morphological differences in foraging adaptations to prey choice and feeding strategies h... more Linking morphological differences in foraging adaptations to prey choice and feeding strategies has provided major evolutionary insights across taxa. Here, we combine behavioural and morphological approaches to explore and compare the role of the rostrum (bill) and micro-teeth in the feeding behaviour of sailfish ( Istiophorus platypterus ) and striped marlin ( Kajikia audax ) when attacking schooling sardine prey. Behavioural results from high-speed videos showed that sailfish and striped marlin both regularly made rostrum contact with prey but displayed distinct strategies. Marlin used high-speed dashes, breaking schools apart, often contacting prey incidentally or tapping at isolated prey with their rostra; while sailfish used their rostra more frequently and tended to use a slower, less disruptive approach with more horizontal rostral slashes on cohesive prey schools. Capture success per attack was similar between species, but striped marlin had higher capture rates per minute. ...
The mangrove–seagrass–patch reef (MSP) ecosystem serves as the principal back‐reef nursery for ma... more The mangrove–seagrass–patch reef (MSP) ecosystem serves as the principal back‐reef nursery for many reef fishes in the Caribbean, but the functional roles of habitats that form this seascape remain unclear. We assessed ecosystem and trophic connectivity of two common reef fishes (schoolmaster, Lutjanus apodus; white grunt, Haemulon plumierii) and one predator (great barracuda, Sphyraena barracuda) in a Caribbean MSP ecosystem using acoustic telemetry and natural dietary tracers. Triangulated positions from an acoustic positioning system indicated that L. apodus and H. plumierii relied on multiple habitats within this MSP ecosystem, occupying areas with more cover (lower risk) during the day and areas with less cover (higher risk) at night. During the day, both species exhibited limited movement away from structured habitats (e.g., mangroves, patch reef) and avoided the primary activity space of S. barracuda in the central channel over sand bottom or seagrass. At night, L. apodus mov...
The deep waters of the open ocean represent a major frontier in exploration and scientific unders... more The deep waters of the open ocean represent a major frontier in exploration and scientific understanding. However, modern technological and computational tools are making the deep ocean more accessible than ever before by facilitating increasingly sophisticated studies of deep ocean ecosystems. Here, we describe some of the cutting-edge technologies that have been employed by the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND; www.deependconsortium.org) Consortium to study the biodiverse fauna and dynamic physical-chemical environment of the offshore Gulf of Mexico (GoM) from 0 to 1,500 m.
The capability of early life history stage fishes to access nursery habitat within managed salt m... more The capability of early life history stage fishes to access nursery habitat within managed salt marshes is dependent on their ability to negotiate water control structures (WCSs). Knowledge of swimming ability and hydrodynamic preferences is essential to assess the impact of WCSs on fish movement in managed marshes. These data, however, are lacking for many common estuarine fishes, and the utility of the data for the few species examined thus far is limited. We examined critical swimming speeds and derived linear relationships between fish size and swimming speed for juveniles of six common estuarine fish species of the southeast U.S. and northern Gulf of Mexico coasts. White mullet Mugil curema displayed the greatest swimming ability among these six species and was able to swim against currents C 30 cm s-1 higher than the other species examined at the same size. The remaining species displayed lower critical swimming speeds and were classified into groups of moderate (pinfish Lagodon rhomboides, striped mullet Mugil cephalus) or slow (silver perch Bairdiella chrysoura, spotfin mojarra Eucinostomus argenteus, spot Leiostomus xanthurus) swimmers. Our results suggest that high-flow conditions at WCSs would likely preclude the passage of all but the largest juvenile fishes, and passage for most juveniles would occur under low-flow conditions; these flows at WCSs are dictated largely by sitespecific tidal and weather conditions.
Lutjanid snappers are ubiquitous at reef sites in the northern Gulf of Mexico (Gulf), but the deg... more Lutjanid snappers are ubiquitous at reef sites in the northern Gulf of Mexico (Gulf), but the degree of niche overlap and basal resource utilization is unknown for most species. Muscle tissue for stable isotope analysis was opportunistically sampled from red snapper (Lujanus campechanus), gray snapper (Lutjanus griseus), lane snapper (Lutjanus synagris), and vermilion snapper (Rhomboplites aurorubens) recreational catches across the northern Gulf. A Bayesian mixing model used to compare resource utilization indicated that Lutjanids occupy niches with varying degrees of overlap among regions but maintain a consistent hierarchy in isotopic composition. Scale shifts among regions were likely due to differences in riverine outflow, nitrogen fixation, and anoxic zones that alter prey abundance or isotopic δ15N ratios. All four Lutjanid species had high percent contributions from particulate organic matter and benthic microalgae with little contribution by macroalgae to any species in any...
The formation of fish spawning aggregations (FSAs) is an essential part of the life history of ma... more The formation of fish spawning aggregations (FSAs) is an essential part of the life history of many economically important fish species; however, their status are often poorly described in the literature either due to their occurrence in remote locations, during seasons with unsafe ocean conditions, or because they move on space and time scales that are difficult to predict and validate. Even in areas that are relatively accessible and heavily fished, such as southeast Florida, regionally relevant information describing FSA dynamics is generally absent from the literature and unaccounted for in existing management plans. We propose that this can be attributed to the fact that information is often held by stakeholders or found in unpublished manuscripts and reports. These sources are not widely disseminated and are therefore difficult to locate and integrate into fisheries management decisions. In this paper, we present a case study demonstrating the value of regional data syntheses ...
Ecosystem services are anthropocentric. They are the benefits that humans receive from the natura... more Ecosystem services are anthropocentric. They are the benefits that humans receive from the natural environment. Yet, do we really consider the potential impact on human well-being as we plan, execute, and monitor restoration and conservation projects? And if we are, is there a real connection between the biophysical structure, function, and processes to ecosystem services and then human well-being? There currently exists a significant opportunity in the Gulf of Mexico to change the way we conduct our "restoration" business. Ecosystem services can play a role in selection among project alternatives but more importantly it can help elucidate the benefits of restoration and be a measure of the "impact of investment" that is being made.
The pelagic Gulf of Mexico (GoM) is a complex system of dynamic physical oceanography (western bo... more The pelagic Gulf of Mexico (GoM) is a complex system of dynamic physical oceanography (western boundary current, mesoscale eddies), high biological diversity, and community integration via diel vertical migration and lateral advection. Humans also heavily utilize this system, including its deep-sea components, for resource extraction, shipping, tourism, and other commercial activity. This utilization has had impacts, some with disastrous consequences. The Deepwater Horizon oil spill (DWHOS) occurred at a depth of ∼1500 m (Macondo wellhead), creating a persistent and toxic mixture of hydrocarbons and dispersant in the deep-pelagic (water column below 200 m depth) habitat. In order to assess the impacts of the DWHOS on this habitat, two large-scale research programs, described herein, were designed and executed. These programs, ONSAP and DEEPEND, aimed to quantitatively characterize the oceanic ecosystem of the northern GoM and to establish a time-series with which natural and anthrop...
Observing multiple size classes of organisms, along with oceanographic properties and water mass ... more Observing multiple size classes of organisms, along with oceanographic properties and water mass origins, can improve our understanding of the drivers of aggregations, yet acquiring these measurements remains a fundamental challenge in biological oceanography. By deploying multiple biological sampling systems, from conventional bottle and net sampling to in situ imaging and acoustics, we describe the spatial patterns of different size classes of marine organisms (several microns to ∼10 cm) in relation to local and regional (m to km) physical oceanographic conditions on the Delaware continental shelf. The imaging and acoustic systems deployed included (in ascending order of target organism size) an imaging flow cytometer (CytoSense), a digital holographic imaging system (HOLOCAM), an In Situ Ichthyoplankton Imaging System (ISIIS, 2 cameras with different pixel resolutions), and multi-frequency acoustics (SIMRAD, 18 and 38 kHz). Spatial patterns generated by the different systems show...
Editorial on the Research Topic Deep Pelagic Ecosystem Dynamics in a Highly Impacted Water Column... more Editorial on the Research Topic Deep Pelagic Ecosystem Dynamics in a Highly Impacted Water Column: The Gulf of Mexico After Deepwater Horizon AIMS AND OBJECTIVES OF RESEARCH TOPIC The intermediate-sized midwater fauna (fishes, shrimps, and cephalopods; "micronekton" collectively) are dominant components of the pelagic ocean, which is by far the largest ecosystem type on Earth by several metrics (volume, organismal numbers, biomass, and productivity). Deeppelagic micronekton, those animals residing in the water column below 200 m depth during the day, are the direct link between plankton and oceanic top predators, and through the linked processes of feeding and daily vertical migration facilitate one of Earth's most important ecosystem services to humans, carbon sequestration. Despite increasing recognition of this importance, a disconnect exists between stewardship and human impact; only a miniscule fraction of the deeppelagic ocean has been studied in detail, while anthropogenic threats to that system are increasing rapidly. Perhaps nowhere on Earth is that dichotomy more demonstrable than the Gulf of Mexico (Gulf hereafter), a complex, high-diversity ecosystem under intense human usage and subjected to arguably the worst marine pollution event in human history. Assessment of the impacts of the Deepwater Horizon disaster to the deep-pelagic biota was impeded from the start by the lack of pre-event information, both in terms of baselines (faunal composition, abundance, and distribution) and in terms of understanding natural variability, against which impacts of anthropogenic disturbance could be detected and quantified. In this Research Topic, we present a description of three interlinked research programs (ONSAP, DEEPEND, and DEEPEND|RESTORE, described below) that began in 2010 and continue as of this writing. These programs were designed to investigate key aspects of the Gulf pelagic ecosystem, including its faunal structure, biophysical drivers of that structure, organismal and community ecology, natural variability, and potential resilience to disturbance. The contributed papers are grouped below by major themes, indicated in the conceptual model (Figure 1) of DEEPEND (Deep Pelagic Nekton Dynamics; www.deependconsortium.org), the largest of the three aforementioned research programs.
The ocean’s mesopelagic zone is largely uncharacterized despite its vital role in sustaining ocea... more The ocean’s mesopelagic zone is largely uncharacterized despite its vital role in sustaining ocean ecosystems. The composition, cycling, and fate of particle fields in the mesopelagic lacks an integrative multi-scale understanding of organism migration patterns, distribution, and diversity. This problem is addressed by combining complementary technologies with overlapping size spectra, including profiler mounted optical scattering sensors, profiler, and ship mounted acoustic devices, and a custom Unobtrusive Multi-Static Lidar Imager (UMSLI). This unique sensor suite can observe distributions of particles including organisms over a six order of magnitude dynamic size range, from microns to meters. Overlapping size ranges between different methods allows for cross-validation. This work focuses on the lidar imaging measurements and optical backscattering and attenuation, covering a combined particle size range of 0.1 mm to several cm. Particles at the small end of this range are sized...
Understanding the stress responses of sharks to recreational catch and release fishing has import... more Understanding the stress responses of sharks to recreational catch and release fishing has important management and conservation implications. The blacktip shark Carcharhinus limbatus is a popular recreational species targeted throughout the western, central and eastern Gulf of Mexico (Gulf) yet it is unclear what levels of physiological stress result from catch-release fishing practices with hook and line gear and if the stress levels result in post-release mortality. This study correlates physiological response to stress through blood chemistry analysis and examines post-release behaviour of adult blacktip sharks caught to determine post-release mortality rates. Release behaviour was determined by pop-up satellite archival transmitting (PSAT) tags that record temperature, depth and light level data. To quantify physiological stress levels, blood samples were collected from 52 blacktip sharks and a suite of metabolic and osmotic markers were measured. Thirty-six of those blacktip s...
Oceanic diel vertical migration (DVM) constitutes the daily movement of various mesopelagic organ... more Oceanic diel vertical migration (DVM) constitutes the daily movement of various mesopelagic organisms migrating vertically from depth to feed in shallower waters and return to deeper water during the day. Accurate classification of taxa that participate in DVM remains non-trivial, and there can be discrepancies between methods. DEEPEND consortium (www.deependconsortium.org) scientists have been characterizing the diversity and trophic structure of pelagic communities in the northern Gulf of Mexico (nGoM). Profiling has included scientific echosounders to provide accurate and quantitative estimates of organismal density and timing as well as quantitative net sampling of micronekton. The use of environmental DNA (eDNA) can detect uncultured microbial taxa and the remnants that larger organisms leave behind in the environment. eDNA offers the potential to increase understanding of the DVM and the organisms that participate. Here we used real-time shipboard echosounder data to direct the sampling of eDNA in seawater at various time-points during the ascending and descending DVM. This approach allowed the observation of shifts in eDNA profiles concurrent with the movement of organisms in the DVM as measured by acoustic sensors. Seawater eDNA was sequenced using a high-throughput metabarcoding approach. Additionally, fine-scale acoustic data using an autonomous multifrequency echosounder was collected simultaneously with the eDNA samples and changes in organism density in the water column were compared with changes in eDNA profiles. Our results show distinct shifts in eukaryotic taxa such as copepods, cnidarians, and tunicates, over short timeframes during the DVM. These shifts in eDNA track changes in the depth of sound scattering layers (SSLs) of organisms and the density of organisms around the CTD during eDNA sampling. Dominant taxa in eDNA samples were mostly smaller organisms that may be below the size limit for acoustic detection, while taxa such as teleost fish were much less abundant in eDNA data compared to acoustic data. Overall, these data suggest that eDNA, may be a powerful new tool for understanding the dynamics and composition of the DVM, yet challenges remain to reconcile differences among sampling methodologies.
Proceedings of the Royal Society B: Biological Sciences, 2020
Linking morphological differences in foraging adaptations to prey choice and feeding strategies h... more Linking morphological differences in foraging adaptations to prey choice and feeding strategies has provided major evolutionary insights across taxa. Here, we combine behavioural and morphological approaches to explore and compare the role of the rostrum (bill) and micro-teeth in the feeding behaviour of sailfish ( Istiophorus platypterus ) and striped marlin ( Kajikia audax ) when attacking schooling sardine prey. Behavioural results from high-speed videos showed that sailfish and striped marlin both regularly made rostrum contact with prey but displayed distinct strategies. Marlin used high-speed dashes, breaking schools apart, often contacting prey incidentally or tapping at isolated prey with their rostra; while sailfish used their rostra more frequently and tended to use a slower, less disruptive approach with more horizontal rostral slashes on cohesive prey schools. Capture success per attack was similar between species, but striped marlin had higher capture rates per minute. ...
The mangrove–seagrass–patch reef (MSP) ecosystem serves as the principal back‐reef nursery for ma... more The mangrove–seagrass–patch reef (MSP) ecosystem serves as the principal back‐reef nursery for many reef fishes in the Caribbean, but the functional roles of habitats that form this seascape remain unclear. We assessed ecosystem and trophic connectivity of two common reef fishes (schoolmaster, Lutjanus apodus; white grunt, Haemulon plumierii) and one predator (great barracuda, Sphyraena barracuda) in a Caribbean MSP ecosystem using acoustic telemetry and natural dietary tracers. Triangulated positions from an acoustic positioning system indicated that L. apodus and H. plumierii relied on multiple habitats within this MSP ecosystem, occupying areas with more cover (lower risk) during the day and areas with less cover (higher risk) at night. During the day, both species exhibited limited movement away from structured habitats (e.g., mangroves, patch reef) and avoided the primary activity space of S. barracuda in the central channel over sand bottom or seagrass. At night, L. apodus mov...
The deep waters of the open ocean represent a major frontier in exploration and scientific unders... more The deep waters of the open ocean represent a major frontier in exploration and scientific understanding. However, modern technological and computational tools are making the deep ocean more accessible than ever before by facilitating increasingly sophisticated studies of deep ocean ecosystems. Here, we describe some of the cutting-edge technologies that have been employed by the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND; www.deependconsortium.org) Consortium to study the biodiverse fauna and dynamic physical-chemical environment of the offshore Gulf of Mexico (GoM) from 0 to 1,500 m.
The capability of early life history stage fishes to access nursery habitat within managed salt m... more The capability of early life history stage fishes to access nursery habitat within managed salt marshes is dependent on their ability to negotiate water control structures (WCSs). Knowledge of swimming ability and hydrodynamic preferences is essential to assess the impact of WCSs on fish movement in managed marshes. These data, however, are lacking for many common estuarine fishes, and the utility of the data for the few species examined thus far is limited. We examined critical swimming speeds and derived linear relationships between fish size and swimming speed for juveniles of six common estuarine fish species of the southeast U.S. and northern Gulf of Mexico coasts. White mullet Mugil curema displayed the greatest swimming ability among these six species and was able to swim against currents C 30 cm s-1 higher than the other species examined at the same size. The remaining species displayed lower critical swimming speeds and were classified into groups of moderate (pinfish Lagodon rhomboides, striped mullet Mugil cephalus) or slow (silver perch Bairdiella chrysoura, spotfin mojarra Eucinostomus argenteus, spot Leiostomus xanthurus) swimmers. Our results suggest that high-flow conditions at WCSs would likely preclude the passage of all but the largest juvenile fishes, and passage for most juveniles would occur under low-flow conditions; these flows at WCSs are dictated largely by sitespecific tidal and weather conditions.
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Papers by Kevin Boswell