R. Dean Grubbs

R. Dean Grubbs
Florida State University | FSU · Florida State University Coastal and Marine Laboratory (FSUCML)

Ph.D.

About

103
Publications
36,571
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2,371
Citations
Citations since 2017
53 Research Items
1537 Citations
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2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300

Publications

Publications (103)
Article
The great hammerhead (Sphyrna mokarran) is a highly mobile, large‐bodied shark primarily found in coastal‐pelagic and semi‐oceanic waters across a circumtropical range. It is a target or bycatch species in multiple fisheries, and as a result, rapid population declines have occurred in many regions. These declines have contributed to the species bei...
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The diet of a potentially omnivorous coastal shark species, the bonnethead (Sphyrna tiburo), was examined in the western Atlantic along the coast of the southeastern United States. A total of 423 stomachs collected from Texas, Alabama, Florida and South Carolina were analyzed using standardized stomach content analysis methods. The diet was dominat...
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Understanding dispersal in large marine fauna is necessary for conservation, but movement patterns often vary widely by sex and life stage. In sharks, genetic studies have shown evidence of widespread male-biased dispersal, though tagging and tracking studies on the same populations show both sexes using site fidelity, including philopatry, and mov...
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Rivers can transport a substantial amount of allochthonous nutrients into coastal marine ecosystems. These nutrients are a significant contributor to estuarine productivity, resulting in increased fishery production. However, for migratory marine predators, the importance of nutrients from fluvial-dominated estuaries is unclear. We used carbon (δ ¹...
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Large estuaries are often highly productive and biodiverse areas of ecological and economical significance. Assessing the movement behavior and space use patterns of mobile organisms in these highly dynamic areas is critical for understanding ecological dynamics within systems. Fine-scale movement data, which is useful for successful species manage...
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Coastal areas serve as vital habitat for many marine fishes and often host broad gradients of environmental conditions that result in diverse species assemblages. Understanding the influence of environmental variables on the distribution and abundance of fishes is especially important for devising appropriate management strategies. We documented la...
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The relationship between phoretic diskfishes and their hosts is a classic example of marine symbiosis, yet surprisingly few studies have quantified this trophic relationship. We investigated the hypothesis that by consuming host parasites and prey scraps phoretic diskfishes (Echeneidae) feed at a higher relative trophic position than free-living in...
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Identifying the geographical scale at which natural populations structure themselves is essential for conservation. One way to gauge this structure is by estimating local effective population size (Ne) and the associated measure of effective number of breeders (Nb), as the smaller and more isolated natural populations are, the smaller Ne and Nb the...
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https://onlinelibrary.wiley.com/share/author/Y2ZSTJNU8YYG2WANCSNF?target=10.1002/aqc.3777 Incidental catch of marine species can create ecological and economic issues, particularly for endangered species. The smalltooth sawfish (Pristis pectinata) is endemic to the Atlantic Ocean and listed as Endangered in the US Endangered Species Act. One of it...
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Oil and gas extraction activities occur across the globe, yet species-specific toxicological information on the biological and ecological impacts of exposure to petrochemicals is lacking for the vast majority of marine species. To help prioritize species for recovery, mitigation, and conservation in light of significant toxicological data gaps, a t...
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The scalloped hammerhead (Sphyrna lewini) and its cryptic congener, Carolina hammerhead (S. gilberti), are sympatrically distributed in the western North Atlantic Ocean. Because the species are indistinguishable based on external morphology, little research focused on Carolina hammerheads exists. In this study, the distribution of Carolina hammerhe...
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Data from the Integrated Tracking of Aquatic Animals in the Gulf of Mexico (iTAG) network, and sister networks, were used to evaluate fish movements in the Florida Keys—an extensive reef fish ecosystem just north of Cuba connecting the Atlantic Ocean and Gulf of Mexico. We analysed ~2 million detections for 23 species, ranging from reef fish such a...
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Migration is common in marine animals,1, 2, 3, 4, 5 and use of the map-like information of Earth’s magnetic field appears to play an important role.²,6, 7, 8, 9 While sharks are iconic migrants10, 11, 12 and well known for their sensitivity to electromagnetic fields,13, 14, 15, 16, 17, 18, 19, 20 whether this ability is used for navigation is unres...
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Marine fish movement plays a critical role in ecosystem functioning and is increasingly studied with acoustic telemetry. Traditionally, this research has focused on single species and small spatial scales. However, integrated tracking networks, such as the Integrated Tracking of Aquatic Animals in the Gulf of Mexico (iTAG) network, are building the...
Article
Marine fish movement plays a critical role in ecosystem functioning and is increasingly studied with acoustic telemetry. Traditionally, this research has focused on single species and small spatial scales. However, integrated tracking networks, such as the Integrated Tracking of Aquatic Animals in the Gulf of Mexico (iTAG) network, are building the...
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The smalltooth sawfish Pristis pectinata is an endangered species endemic to the Atlantic Ocean. The only known viable populations occur in the USA along both coasts of Florida and in the western Bahamas. Little is known about habitat use and movement ecology of large juvenile and adult smalltooth sawfish. Although Critical Habitat—a management des...
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Prior to the Deepwater Horizon (DWH) oil spill, little research effort was focused on studying deep-sea sharks in the Gulf of Mexico (GoM). While the biology of these fishes remains virtually unknown, they are routinely captured in commercial fisheries as bycatch. In the absence of basic biological data, and with the probability of post-release sur...
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• A spatial approach to coastal management, such as marine protected areas, is being increasingly used to address biodiversity and fishery declines resulting from habitat loss, degradation, and overfishing. This approach is especially applicable in regions and fisheries that are data poor, and which often lack regulations and adequate capacity for...
Article
A fundamental understanding of the impact of petrochemicals and other stressors on marine biodiversity is critical for effective management, restoration, recovery, and mitigation initiatives. As species-specific information on levels of petrochemical exposure and toxicological response are lacking for the majority of marine species, a trait-based a...
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Cardiac morphology and mass have been associated with activity levels for bony fishes and elasmobranchs; however, there is little information on cardiac morphology of deep-sea sharks (living primarily below 200 m) and how that morphology compares to cardiac morphology of shallow coastal species. We examined relative heart mass and relative ventricl...
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Fishes are often caught as bycatch on longlines and subsequently discarded. The behavioural response of fishes to longline capture is poorly understood, although it may be linked to the magnitude of the physiological stress response, and, ultimately, contribute to stress-induced mortality. We used accelerometers, video cameras, and hook timers to a...
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Carbon and nitrogen stable isotope analyses were used to infer relative trophic structure and examine regional variation in trophic dynamics of fishes in the Florida Big Bend, an approximately 300 km stretch of relatively pristine coastline in the eastern Gulf Of Mexico that contains over 250,000 ha of seagrass. The Florida Big Bend is home to a di...
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We used fishery-independent gillnet and longline surveys to document the elasmobranch and large teleost assemblages in the Florida Big Bend seagrass system and examine how ichthyofaunal assemblages were related to environmental factors across the region. A total of 159 paired gillnet sets were conducted in June through August from 2009 to 2012. The...
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Given the conservation status and ecological, cultural, and commercial importance of chondrichthyan fishes, it is valuable to evaluate the extent to which research attention is spread across taxa and geographic locations and to assess the degree to which scientific research is appropriately addressing the challenges they face. Here we review trends...
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Discovery of an unusual rectal gland in the Atlantic sixgill shark Hexanchus vitulus led us to examine the rectal glands of 31 species of sharks to study diversity in rectal‐gland morphology. Twenty‐four of 31 species of sharks had digitiform glands (mean width–length ratio ± SD = 0.17 ± 0.04) previously assumed to be characteristic of all elasmobr...
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Genetic polyandry was assessed in 27 litters of Blacknose Shark (Carcharhinus acronotus) from genetically distinct populations in the U.S. Atlantic (19 litters) and eastern Gulf of Mexico (eight litters) using 23 polymorphic microsatellite loci. Two methods were used to estimate genetic polyandry, and the overall observed rates were high (74% COLON...
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Globally, sawfishes are threatened with extinction because they occur in coastal habitats, which are disproportionally affected by human activities. In particular, sawfishes are susceptible to myriad fisheries that operate in the same regions. Unfortunately, these well-documented threats can be only partly mitigated because of ongoing human resourc...
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South Florida has been identified as a genetic break for multiple mobile marine taxa but the mechanisms that impede gene flow largely remain unknown. To understand how South Florida functions as a barrier for blacknose shark, a highly migratory species that has genetically diverged Atlantic and Gulf populations, patterns of genetic variation were a...
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Emerging conservation efforts for the world’s large predators may, if successful, restore natural predator–prey interactions. Marine reserves, where large predators tend to be relatively common, offer an experimental manipulation to investigate interactions between large-bodied marine predators and their prey. We hypothesized that southern stingray...
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The smalltooth sawfish Pristis pectinata is threatened with extinction throughout its range and has been designated as Critically Endangered by the IUCN. In the USA, the species historically ranged from Texas to North Carolina, but mortality in fisheries and habitat loss have reduced the range to primarily southwest Florida. The US population was l...
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Mercury (Hg) concentration in fish of the Gulf of the Mexico (GoM) is a major concern due to the importance of the GoM for U.S. fisheries. The Deepwater Horizon (DWH) oil spill in April 2010 in the northern GoM resulted in large amounts of oil and dispersant released to the water column, which potentially modified Hg bioaccumulation patterns in aff...
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Dogfish sharks of the genus Squalus are small, deep-water sharks with a slow rate of molecular evolution that has led to their designation as a series of species complexes, with low between-species diversity relative to other taxa. The largest of these complexes is named for the Shortspine spurdog (Squalus mitsukurii Jordan & Snyder), a medium-size...
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Highly productive, protected habitats have been shown to serve as nurseries for many marine fishes. However, few studies quantitatively measure the biotic characteristics that often drive a habitat's function as a nursery. We used a combination of passive acoustic monitoring and quantification of biotic attributes to assess nursery habitat use of j...
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This study describes growth and reproductive characteristics of a facultative elasmobranch symbiont, the sharksucker (remora) Echeneis naucrates, from the eastern Gulf of Mexico. Females grew slower but achieved a larger size than males and host–symbiont length ratios increased linearly with E. naucrates length Mean relative batch fecundity was 39....
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Sharks of the genus Squalus have slow reproductive rates coupled with low genetic diversity, as is typical of deep-water sharks, making this group slow to rebound from depletion due to overfishing. The number of species within Squalus has been expanding recently due to increased attention on taxonomic revision, and a growing research focus on littl...
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Similar to other elasmobranchs, the smalltooth sawfish Pristis pectinata is slow growing, matures late in life, and produces relatively few young, all factors that have contributed to its sensitivity to dramatic population declines from overfishing and habitat loss. Currently, the physiological stress response of these fish to capture or to other p...
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The sixgill sharks of the genus Hexanchus (Hexanchiformes, Hexanchidae) are large, rarely encountered deep-sea sharks, thought to comprise just two species: the bluntnose sixgill Hexanchus griseus (Bonaterre, 1788) and the bigeye sixgill Hexanchus nakamurai (Teng, 1962). Their distribution is putatively worldwide in tropical and temperate waters, b...
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Animal performance is tightly linked to morphological function, whereby changes in size and performance can influence niche dynamics over ontogeny. To understand how growth affects feeding performance, we examined how bite force over ontogeny differed between two populations of durophagous stingrays, Rhinoptera bonasus (from the Chesapeake Bay and...
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Bycatch interactions with deep-sea elasmobranchs are increasingly common and can lead to dramatic declines in abundance over short time scales. Sharks hooked in the deep sea could face a higher likelihood of severe physiological disturbance, at-vessel mortality, and postrelease mortality (PRM) than their shallower counterparts. Unfortunately, robus...
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Herein, we use genetic data from 277 sleeper sharks to perform coalescent-based modeling to test the hypothesis of early Quaternary emergence of the Greenland shark (Somniosus microcephalus) from ancestral sleeper sharks in the Canadian Arctic-Subarctic region. Our results show that morphologically cryptic somniosids S. microcephalus and Somniosus...
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Deep-sea chondrichthyans are cryptic species subject to increasing anthropogenic exploitation. Defining their role in deep-water ecosystems is therefore crucial for predicting the ecosystem-wide effects of their removal. Stable isotope analyses (SIA) of carbon and nitrogen have been increasingly used in chondrichthyan studies as a non-lethal method...
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Growing concerns about the conservation of elasmobranchs have prompted a surge in research because scientific studies are needed that can support management actions. Sawfishes are among the most threatened fishes worldwide and epitomize the challenge of conserving widely distributed, large-bodied marine fishes. A comparative approach was used to pr...
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We employed catch data from 2 fishery-independent shark surveys conducted from 2009–2012, as well as stable isotope analysis, to investigate potential effects of the 2010 Deepwater Horizon oil spill on large coastal fishes in Florida's Big Bend region. The catch-per-unit-effort of 5 indicator species (3 sharks and 2 teleosts) varied significantly a...
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Quantifying changes in blood chemistry in elasmobranchs can provide insights into the physiological insults caused by anthropogenic stress, and can ultimately inform conservation and management strategies. Current methods for analysing elasmobranch blood chemistry in the field are often costly and logistically challenging. We compared blood pH valu...
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Biologging and tracking instruments provide valuable, remote surveillance on otherwise unobservable marine animals. Instruments can be consumed (ingested) by predators while collecting data, and if not identified, the retrieved dataset could be assigned to the incorrect individual and/or species. Consumption events of instruments, such as pop-up sa...
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A thorough understanding of movement patterns of a species is critical for designing effective conservation and management initiatives. However, generating such information for large marine vertebrates is challenging, as they typically move over long distances, live in concealing environments, are logistically difficult to capture and, as upper-tro...
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Here we consider the role of depth as a driver of evolution in a genus of deep-sea fishes. We provide a phylogeny for the genus Coryphaenoides (Gadiformes: Macrouridae) that represents the breadth of habitat use and distributions for these species. In our consensus phylogeny species found at abyssal depths (> 4000 m) form a well-supported lineage,...
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Isopods are micropredators of deep-water sharks; however, their associations are poorly described in the scientific literature. We present the association of three isopod genera Aega sp., Aegaphales sp., and Cirolana sp. with two species of deep-sea shark, the Cuban dogfish (Squalus cubensis) and the sharpnose sevengill (Heptranchias perlo). Althou...
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Estimates of post-release mortality (PRM) rates for discarded bycatch are largely unknown across marine fisheries and represent a substantial source of uncertainty when estimating total fishery mortality. One way to predict PRM is through the use of reflex action mortality predictors (RAMP), whereby the presence or absence of target reflexes and kn...
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A combination of mark-recapture and genetic sampling was used to extend the minimum longevity of an elasmobranch species and the life span estimate of the lemon shark Negaprion brevirostris was increased conservatively from 20·2 to 37 years. This increase in longevity means higher vulnerability and a longer recovery time from exploitation.
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When identifying potential trophic cascades, it is important to clearly establish the trophic linkages between predators and prey with respect to temporal abundance, demographics, distribution, and diet. In the northwest Atlantic Ocean, the depletion of large coastal sharks was thought to trigger a trophic cascade whereby predation release resulted...
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This study documents and discusses recent (2002–2015) sightings and captures of smalltooth sawfish Pristis pectinata in the Bahamas. Movement patterns and habitat preferences of five P. pectinata are examined: two tracked with acoustic telemetry in Bimini and three tagged with pop-up archival transmitting tags in Andros. Historically, P. pectinata...
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Identification of sharks within the genus Mustelus (smoothhound sharks) is problematic because of extensive overlap in external morphology among species. Consequently, species-specific management of smoothhound shark resources is difficult when multiple species inhabit the same geographic region. The species identification and distribution of smoot...
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Growth affects the performance of structure, so the pattern of growth must influence the role of a structure and an organism. Because animal performance is linked to morphological specialization, ontogenetic change in size may influence an organism's biological role. High bite force generation is presumably selected for in durophagous taxa. Therefo...
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Modes of reproduction and embryonic development vary greatly among the elasmobranchs, and prior studies have suggested that the energetic toll of embryogenesis in lecithotrophic species depletes embryonic organic matter by 20% or more. Matrotrophic species experience a lesser reduction or an increase in organic matter during embryogenesis. To inves...
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Identifying essential habitat for large, mobile endangered species is difficult, particularly marine species where visual observations are limited. Though various methods of telemetry are available, each suffers from limitations and only provides satisfactory information over a specific temporal or spatial scale. Sawfish are one of the most imperil...
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Deep-sea chondrichthyans, like many deep-water fishes, are very poorly understood at the most fundamental biological, ecological and taxonomic levels. Our study represents the first ecological investigation of deep-water elasmobranch assemblages in The Bahamas, and the first assessment of species-specific resilience to capture for all of the specie...
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Habitat use studies can be used to investigate ecological and behavioural patterns of animals and serve as useful tools for conservation planners. However, specific habitats essential to survival can be difficult to determine for highly mobile marine animals, especially when these species are rare or endangered.Active acoustic tracking telemetry wa...
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Coastal shark abundance and community struc-ture was quantified across 10 geographic areas in the northeastern Gulf of Mexico using fishery-independent gillnet data from 2003 to 2011. A total of 3,205 sets were made in which 14,244 carcharhiniform sharks, primarily juveniles, were caught comprising 11 species from three families. The three most abu...
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Patterns of population structure and historical genetic demography of blacknose sharks in the western North Atlantic Ocean were assessed using variation in nuclear-encoded microsatellites and sequences of mitochondrial (mt)DNA. Significant heterogeneity and/or inferred barriers to gene flow, based on microsatellites and/or mtDNA, revealed the occur...
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Chondrichthyans (sharks, batoids, and chimaeras) have simple feeding mechanisms owing to their relatively few cranial skeletal elements. However, the indirect association of the jaws to the cranium (euhyostylic jaw suspension) has resulted in myriad cranial muscle rearrangements of both the hyoid and mandibular elements. We examined the cranial mus...