Charles Martin
University of South Alabama, Marine Sciences, Faculty Member
- Dauphin Island Sea Lab, Estuarine Ecology, Faculty MemberLouisiana State University, Oceanography and Coastal Sciences, Post-DocUniversity of Florida, UF/IFAS Nature Coast Biological Station, Faculty Memberadd
- Marine Ecology, Freshwater Ecology, Invasive species ecology, Fish Ecology, Wetlands, Fish and Marine Ecology, and 10 moreInvasive Species, Predator-Prey Interactions, Food web ecology, Ecology, Conservation Biology, Biodiversity, Marine Biology, Fish Biology, Biology, and Environmental Sustainabilityedit
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can provide additional food resources and habitat complexity, leading to increased animal abundance, but large concentrations can also inhibit faunal... more
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can provide additional food resources and habitat complexity, leading to increased animal abundance, but large concentrations can also inhibit faunal movements, smother benthic communities, and contribute to hypoxia, reducing nekton abundance. Despite its ubiquity, few studies have quantified drift macroalgal prevalence over large spatial scales or its effects on seagrass-associated nekton, hindering our understanding of the functional role of drift macroalgae in ecosystems. We quantified the relationship between drift macroalgal biomass and the seagrass-associated nekton community within five estuaries spanning 2000 km across the northern Gulf of Mexico. Overall, increases in macroalgal biomass within seagrass meadows significantly influenced community structure, increasing shrimp, crab, and fish abundances, but the effect varied by region. Relationships between species richness, diversity, organis...
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Seagrass meadows provide greater predator refuge and resource availability than unvegetated habitats and generally improve the survival and growth rates of associated animals. Few studies, however, have examined how these relationships... more
Seagrass meadows provide greater predator refuge and resource availability than unvegetated habitats and generally improve the survival and growth rates of associated animals. Few studies, however, have examined how these relationships might vary at a region-wide spatial scale. The blue crab Callinectes sapidus is a commercially important species that uses turtlegrass Thalassia testudinum habitats, but it is unclear if blue crab use of seagrass habitats varies across the northern Gulf of Mexico (GOM), USA. We conducted synoptic predation and growth experiments at 6 turtlegrass-dominated estuaries in the northern GOM to evaluate the role of seagrass structural complexity on juvenile (9.7-44 mm carapace width) blue crab mortality due to predation and growth. Relationships of blue crab predation and growth rate with seagrass shoot density, canopy height, temperature, and seagrass leaf area index (LAI) were evaluated using linear and generalized linear mixed effects models. Mortality ra...
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produce active (i.e., intentional) sounds. Active fish sound production is geographically and taxonomically widespread-though not homogenous-among fishes, contributing a cacophony of biological sounds to the prevailing soundscape... more
produce active (i.e., intentional) sounds. Active fish sound production is geographically and taxonomically widespread-though not homogenous-among fishes, contributing a cacophony of biological sounds to the prevailing soundscape globally. Our inventory supports previous findings on the prevalence of actively soniferous fishes, while allowing novel species-level assessments of their distribution among regions and taxa. Furthermore, we evaluate commercial and management applications with passive acoustic monitoring, highlight the underrepresentation of research on passive (i.e., incidental) fish sounds in the literature, and quantify the limitations of current methodologies employed to examine fishes for sound production. Collectively, our review expands on previous studies while providing the foundation needed to examine the 96% of fish species that still lack published examinations of sound production.
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Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase the value of seagrass beds as habitat for nekton via added food resources and structural complexity. But, as algal biomass increases, it can... more
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase the value of seagrass beds as habitat for nekton via added food resources and structural complexity. But, as algal biomass increases, it can also decrease light availability, inhibit faunal movements, smother benthic communities, and contribute to hypoxia, all of which can reduce nekton abundance. We quantified the abundance and distribution of drift macroalgae within seagrass meadows dominated by turtle grass Thalassia testudinum across the northern Gulf of Mexico and compared seagrass characteristics to macroalgal biomass and distribution. Drift macroalgae were most abundant in areas with higher seagrass shoot densities and intermediate canopy heights. We did not find significant relationships between algal biomass and point measures of salinity, temperature, or depth. The macroalgal genera Laurencia and Gracilaria were present across the study region, Agardhiella and Digenia were col...
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The Diamond-backed Terrapin (Malaclemys terrapin) inhabits coastal islands along the Gulf coast of Florida (sometimes in numbers > 100), but factors associated with terrapin occurrence on islands are poorly understood. We conducted a... more
The Diamond-backed Terrapin (Malaclemys terrapin) inhabits coastal islands along the Gulf coast of Florida (sometimes in numbers > 100), but factors associated with terrapin occurrence on islands are poorly understood. We conducted a study of terrapin occupancy on coastal islands in the Suwannee Estuary in Florida. We used remote sensing to assess 24 discrete islands, and in 2017-2018 we conducted terrapin surveys twice per year on each island. Our results indicated that terrapin occurrence was negatively associated with increased forest coverage and positively associated with increased distance from the mainland, whereas other characteristics we measured (e.g., island size, mangrove coverage, and grass coverage) were not relevant predictors of terrapin occurrence. Overall, terrapins potentially occupy more isolated islands that are less likely inhabited by predators. Although more research is needed, this is potentially a conservation concern because these islands may lose their suitability due to sea-level rise, forcing terrapins to relocate to potentially less suitable habitats that could negatively affect nesting, survival rates, and population persistence.
produce active (i.e., intentional) sounds. Active fish sound production is geographically and taxonomically widespread-though not homogenous-among fishes, contributing a cacophony of biological sounds to the prevailing soundscape... more
produce active (i.e., intentional) sounds. Active fish sound production is geographically and taxonomically widespread-though not homogenous-among fishes, contributing a cacophony of biological sounds to the prevailing soundscape globally. Our inventory supports previous findings on the prevalence of actively soniferous fishes, while allowing novel species-level assessments of their distribution among regions and taxa. Furthermore, we evaluate commercial and management applications with passive acoustic monitoring, highlight the underrepresentation of research on passive (i.e., incidental) fish sounds in the literature, and quantify the limitations of current methodologies employed to examine fishes for sound production. Collectively, our review expands on previous studies while providing the foundation needed to examine the 96% of fish species that still lack published examinations of sound production.
Established natural oyster reefs historically provide a three-dimensionally complex habitat utilized by a variety of resident and transient species, but newly created reefs designed to counter the loss of natural reefs initially may lack... more
Established natural oyster reefs historically provide a three-dimensionally complex habitat utilized by a variety of resident and transient species, but newly created reefs designed to counter the loss of natural reefs initially may lack similar complexity. The loosely stacked shells of newly created reefs little resemble the vertically interconnected live and dead shell matrix typical of older reefs. Reduced complexity on created reefs may alter predator-prey dynamics and negatively affect ecological functions typically associated with natural reefs. We examined select physical characteristics (e.g. shell morphology) and short-term survival of reef-resident prey to determine if differences exist between newly created (<1-year-old shell bags) and established natural intertidal reefs in South Carolina. Shell physical characteristics differed consistently between reefs, with greater numbers of smaller and lighter shells found on natural reefs. However, short-term survival of crabs (Panopeid sp.) and mussels (Geukensia demissa) generally was not dependent on reef type. The few instances of reef dependent prey survival were either inconsistent with expected results, assuming reduced complexity on created reefs, or not supported by effect size analyses. Evidence indicates that adding shell bags to create oyster reefs in intertidal environments almost immediately increases resident species survival similar to that on existing natural reefs and leads to the rapid return of a major ecosystem service associated with coastal oyster reefs.
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase the value of seagrass beds as habitat for nekton via added food resources and structural complexity. But, as algal biomass increases, it can... more
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase the value of seagrass beds as habitat for nekton via added food resources and structural complexity. But, as algal biomass increases, it can also decrease light availability, inhibit faunal movements, smother benthic communities, and contribute to hypoxia, all of which can reduce nekton abundance. We quantified the abundance and distribution of drift macroalgae within seagrass meadows dominated by turtle grass Thalassia testudinum across the northern Gulf of Mexico and compared seagrass characteristics to macroalgal biomass and distribution. Drift macroalgae were most abundant in areas with higher seagrass shoot densities and intermediate canopy heights. We did not find significant relationships between algal biomass and point measures of salinity, temperature, or depth. The macroalgal genera Laurencia and Gracilaria were present across the study region, Agardhiella and Digenia were collected in the western Gulf of Mexico, and Acanthophora was collected in the eastern Gulf of Mexico. Our survey revealed drift algae to be abundant and widespread throughout seagrass meadows in the northern Gulf of Mexico, which likely influences the habitat value of seagrass ecosystems.
Many fish species use active sound production for communication in numerous behaviors. Additionally, likely all fish can make passive or incidental sounds that may also serve some signal functions. Despite the ecological importance of... more
Many fish species use active sound production for communication in numerous behaviors. Additionally, likely all fish can make passive or incidental sounds that may also serve some signal functions. Despite the ecological importance of fish sounds, their evident passive acoustic monitoring applications, and extensive endeavors to document soniferous fish diversity, the fields of bioacoustics and ichthyology have historically lacked an easily accessible, global inventory of known fish sound production. To alleviate this limitation, we developed htt p://FishSounds.net, a website that compiles and disseminates fish sound production information and recordings. FishSounds Version 1.0 launched in 2021, cataloging documented examinations for active and passive sound production for 1185 fish species from 837 references as well as 239 exemplary audio recordings. Fish-Sounds allows users to search by taxa (e.g., family or common name), geographical distribution (e.g., region or water body), sound type, or reference. We have also made available the code used to create the website, so that it may be used in other data-sharing efforts-acoustic or otherwise. Subsequent versions of the website will update the data and improve the website functionality. FishSounds will advance research into fish behavior, passive acoustic monitoring, and human impacts on underwater soundscapes; serve as a resource for public outreach; and provide the foundation needed to investigate more of the 96% of fish species that lack published examinations of sound production. We further hope the FishSounds design, implementation, and engagement strategies will serve as a model for future data management and sharing efforts.
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can provide additional food resources and habitat complexity, leading to increased animal abundance, but large concentrations can also inhibit faunal... more
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can provide additional food resources and habitat complexity, leading to increased animal abundance, but large concentrations can also inhibit faunal movements, smother benthic communities, and contribute to hypoxia, reducing nekton abundance. Despite its ubiquity, few studies have quantified drift macroalgal prevalence over large spatial scales or its effects on seagrassassociated nekton, hindering our understanding of the functional role of drift macroalgae in ecosystems. We quantified the relationship between drift macroalgal biomass and the seagrass-associated nekton community within five estuaries spanning 2000 km across the northern Gulf of Mexico. Overall, increases in macroalgal biomass within seagrass meadows significantly influenced community structure, increasing shrimp, crab, and fish abundances, but the effect varied by region. Relationships between species richness, diversity, organism size, and macroalgal biomass were not observed, suggesting that drift macroalgae provide additional habitat but not necessarily new niche space. Small nekton play a vital role in many local fisheries, providing valuable food resources for fish and invertebrates. Increased recruitment into macroalgae can benefit local fisheries by providing shelter and increased food resources, which may increase the survival, growth, and population size of recreationally and economically important species. While excess levels of drift macroalgae can negatively impact benthic plant and animal communities, particularly in eutrophic areas, the moderate levels observed during this survey were associated with positive effects on organismal abundance, suggesting that drift algal dynamics should be considered in habitat-based management strategies for coastal estuaries.
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A warming climate is driving the poleward expansion of tropical, subtropical, and temperate plant and animal distributions. These changes have and continue to lead to the colonization of novel organisms into areas beyond their historical... more
A warming climate is driving the poleward expansion of tropical, subtropical, and temperate plant and animal distributions. These changes have and continue to lead to the colonization of novel organisms into areas beyond their historical ranges. While the full scope of ecological impacts remains unclear, these expansions could alter densitydependent interactions, habitat occupancy patterns, and food web dynamics-similar to exotic species impacts in invaded ecosystems. Seagrasses are habitats of particular interest, given their widespread distribution and ecosystem services. While multiple recent studies report on the effects of the return of larger tropical herbivores in seagrass beds in warming subtropical waters, less is known about the addition of mid-trophic level consumers. These consumers are often key determinants of energy and nutrient transfers from basal resources to higher order predators. Here, we discuss the potential impacts of these distribution changes on temperate and subtropical seagrass communities using information derived from invasive species studies. Notably, we outline several scenarios and generate predictions about how their establishment might occur and speculate on impacts of warmer water consumers as they move poleward. We also discuss potential confounding factors of detecting changes in these consumer distributions. Following the invasive species literature, we offer a framework for generating hypotheses and predicting effects from these range-expanding organisms. Given that climates are predicted to continue to warm into the future, thus facilitating additional species expansions, our goal is to guide future research efforts and provide information for rapid dissemination and utility for this growing subdiscipline of marine ecology.
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Salt marsh ecosystems and the seascapes in which they are embedded serve as critical habitats for species harvested by fisheries (1), which provide food and economic security for hundreds of millions of people (2). Historical marsh losses... more
Salt marsh ecosystems and the seascapes in which they are embedded serve as critical habitats for species harvested by fisheries (1), which provide food and economic security for hundreds of millions of people (2). Historical marsh losses coupled with increasing pressures from coastal development and climate change place these intertidal ecosystems and surrounding uplands under growing threat (3). Preventing further losses of salt marshes and associated fisheries production will require greater public awareness and difficult choices in coastal policy and management, underpinned by greater understanding of marsh function.
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Temperatures are increasing globally and causing species-specific geographic range expansions. In the Gulf of Mexico, mangroves are encroaching regions historically dominated by temperate salt marshes, changing animal communities and... more
Temperatures are increasing globally and causing species-specific geographic range expansions. In the Gulf of Mexico, mangroves are encroaching regions historically dominated by temperate salt marshes, changing animal communities and nutrient cycling in the intertidal zone. Marine systems are highly connected; therefore, we expect that changes in the intertidal will alter functions of adjacent subtidal seagrass meadows. We surveyed seagrass meadows adjacent to mangroves, salt marshes, and a mixture of the two and asked, do changes in intertidal plant composition influence (1) environmental conditions (subtidal water and sediment characteristics); (2) biogeochemical cycling (net oxygen and nitrogen gas fluxes); (3) seagrass meadow cover, biomass, and productivity; and (4) invertebrate community assemblage? There are clear differences in sediment organic matter and net nitrogen gas (N2) fluxes between adjacent intertidal habitats, but the magnitude or direction of change differs seasonally. We hypothesize that this seasonal pattern is due to outwelling from the intertidal, as mangroves senesce in fall, and marshes senesce later in winter. Therefore, changes in adjacent intertidal habitat can impact the timing of organic matter delivery. This also has implications for seagrass biomass. Thalassia testudinum belowground biomass adjacent to mangroves substantially decreased over the winter, suggesting vulnerability to stressors as the intertidal plant community shifts from marsh to mangrove dominance. Epifauna density and diversity did not vary among seagrass meadows based on adjacent intertidal habitats, but subtle differences in community assemblages associated with shifts in intertidal plant community were detected. This work demonstrates that impacts of species range expansions are far-reaching due to connectivity in marine systems.
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Small variations in environmental parameters can substantially alter species composition, but the extent to which different species respond to these changes remains obscure. A synoptic survey of seagrass-associated faunal communities was... more
Small variations in environmental parameters can substantially alter species composition, but the extent to which different species respond to these changes remains obscure. A synoptic survey of seagrass-associated faunal communities was performed across the Gulf of Mexico using otter trawls coupled with seagrass and water quality assessments. The abundance of eight central seagrass inhabitants, representing a range of functional groups, were quantified to identify factors that best predicted their prevalence across environmental gradients and the consistency of these ecological relationships. Seagrass density and drift algal biomass generally had the strongest influence on animal abundance (40–67%), although relationships with drift algae were species specific and seemingly related to faunal size and mobility. Abundances of free-swimming pinfish, pigfish, and silver perch were negatively related to drift algae biomass (0.7, 0.7, and 1.0% Δ per 1 g·m−2 drift algae, respectively), whereas the abundance of pipefish (Syngnathus spp.) and brown/pink shrimp (Penaeus spp.) tended to be positively related to algal biomass (0.8 and 1.6% Δ per 1 g·m−2 drift algae). Shrimp abundances increased by 3.6% per 1% increase in light attenuation while the abundance of a higher-order visual predator, silver perch, negatively responded to light attenuation (1.1% Δ per 1% Δ vertical light attenuation). Additionally, bivariate plots of organismal abundance and salinity or canopy height indicated a unimodal relationship with peaks in abundance associated with intermediate values for several species. This study explored the extent species and functional groups responded to variation in key elements of the abiotic and biotic environment, providing insight into community development and offering resource managers quantitative targets for aspects of habitat quality.
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Submerged aquatic vegetation (SAV) improves environmental conditions by acting as a sediment stabilizer and nutrient retention tool; therefore, reintroduction of SAV is a common freshwater restoration goal. Initial plant establishment is... more
Submerged aquatic vegetation (SAV) improves environmental conditions by acting as a sediment stabilizer and nutrient retention tool; therefore, reintroduction of SAV is a common freshwater restoration goal. Initial plant establishment is often difficult in suboptimal conditions, and planting material with specific traits may increase establishment rates. Here we evaluate the variability in plant traits based on collection location. We find consistent differences in traits of plants collected from different natural water bodies, and those differences persist in plants grown from seeds under common garden greenhouse conditions—presumably because of genetic differentiation. In three separate mesocosm experiments, we tested the interactive impacts of collection location and environmental condition (control conditions, reduced light, elevated nutrients, or a combination of reduced light and elevated nutrients) on plant reproduction and on traits that might indicate future restoration success (plant height, number of leaves, and rhizome diameter). In most cases, plant traits at the end of the experiments varied by collection location, environmental condition, and an interaction between the two. The best performing plants also depended on response variable (e.g., plant height or number of new shoots produced). Together these results suggest that unpredictable environmental conditions at restoration sites will make selection of a single high-performing plant source difficult, so we suggest incorporating a diverse set of collection locations to increase the probability of incorporating desirable traits.
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Abstract Vallisneria americana typically produces solitary pistillate inflorescences; however, unusual umbellate flowers have been observed in sub-tropical populations and are reported as rare. There are multiple hypotheses regarding the... more
Abstract Vallisneria americana typically produces solitary pistillate inflorescences; however, unusual umbellate flowers have been observed in sub-tropical populations and are reported as rare. There are multiple hypotheses regarding the origin or cause of umbellate inflorescences—they may be relics of ancestral stocks surviving through asexual reproduction, heritable traits worthy of taxonomic recognition, or teratological specimens resulting from injury during flower formation. Through surveys of Vallisneria populations in four lakes in Central Florida, USA, we show these umbellate flowers are broadly distributed and we document their physical and reproductive traits, contrasted with solitary capsules (capsule number, capsule length and width, seed number, germination). Umbellate inflorescences were found frequently across space and time—capsules were found in three of four lakes, 40–80 % of the times flowering was observed. Umbellate inflorescences produced fewer seeds than solitary capsules, despite having 2–33 capsules per inflorescence. Seeds from umbellate capsules were viable, but germination occurred more slowly and at a lower percentage than seeds from solitary capsules. Nematodes were not detected within sampled inflorescences. Chironomid larvae were detected at a high rate (75–80 %) in umbellate capsules from two of three lakes but were not found on solitary capsules, suggesting they may be a possible cause for teratological growth. We conclude umbellate inflorescences are broadly distributed in Central Florida lakes and, while not sterile, they may have reproductive costs. Further study is needed to fully evaluate the cause of umbellate formation, population-level effects, and their range within Vallisneria americana.
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Submerged aquatic vegetation (SAV) is declining worldwide, leading to subsequent reductions in the ecological functions associated with SAV in shallow aquatic ecosystems, including providing habitat for fishes. Extensive restoration... more
Submerged aquatic vegetation (SAV) is declining worldwide, leading to subsequent reductions in the ecological functions associated with SAV in shallow aquatic ecosystems, including providing habitat for fishes. Extensive restoration efforts are required to reverse this trend, but studies focusing on aquatic vegetation have been uncommon in recent years relative to other primary producers. Evaluations of the most beneficial SAV species and characteristics for fishes are especially rare. Because of the potentially complex and inconsistent responses of fish to different management actions, further research is necessary to evaluate the species-specific and community-level effects of SAV to inform restoration decision-making. To examine what SAV characteristics increase fish habitat use in a turbid-algal lake undergoing restoration, we sampled 29 areas around Lake Apopka, Florida (USA) with fyke nets and trotlines. We examined the impact of eight environmental variables on fish abundance...
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Seagrasses are productive habitats that support diverse communities of economically and ecologically important fishes and macroinvertebrates. However, most seagrass faunal assessments are conducted only during daylight hours. Here, we... more
Seagrasses are productive habitats that support diverse communities of economically and ecologically important fishes and macroinvertebrates. However, most seagrass faunal assessments are conducted only during daylight hours. Here, we documented diel patterns in seagrass-associated fish and macroinvertebrate community structure in seagrass near Seahorse Key, Florida (USA). Artificial light is prevalent in many coastal areas and may influence day/night assemblages; therefore, we added lights to the natural environment to get a better understanding of its effect on community composition. Seagrass inhabitants were quantified using 25-m seine transects during different diel periods (day or night) and in areas where light was manipulated to mimic light pollution (artificial + natural light or natural light). Results suggest that the magnitude of diel effects exceeded that of light addition. While total abundance was similar between day and night, communities did change, with Lagodon rhomboides (Pinfish) dominating day samples and Farfantepenaeus duorarum (pink shrimp) most abundant at night. Other fishes such as Orthopristis chrysoptera (Pigfish) and Strongylura notata (Needlefish) had higher catches during the day, while invertebrates such as Callinectes sapidus (blue crab) and Palaeomonetes spp. (grass shrimp) were more prominent at night. In addition to the differences in abundance and community structure, we also identified diel differences in sizes for some species. No clear patterns were observed with the short-term addition of artificial light. This research highlights the role of diel variability in seagrass communities and suggests that diel movement of organisms may represent an important conduit for the transfer of energy to adjacent habitats.
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Climate change is altering naturally fluctuating environmental conditions in coastal and estuarine ecosystems across the globe. Departures from long-term averages and ranges of environmental variables are increasingly being observed as... more
Climate change is altering naturally fluctuating environmental conditions in coastal and estuarine ecosystems across the globe. Departures from long-term averages and ranges of environmental variables are increasingly being observed as directional changes [e.g., rising sea levels, sea surface temperatures (SST)] and less predictable periodic cycles (e.g., Atlantic or Pacific decadal oscillations) and extremes (e.g., coastal flooding, marine heatwaves). Quantifying the short- and long-term impacts of climate change on tidal marsh seascape structure and function for nekton is a critical step toward fisheries conservation and management. The multiple stressor framework provides a promising approach for advancing integrative, cross-disciplinary research on tidal marshes and food web dynamics. It can be used to quantify climate change effects on and interactions between coastal oceans (e.g., SST, ocean currents, waves) and watersheds (e.g., precipitation, river flows), tidal marsh geomor...
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Oil spills threaten the structure and function of ecological communities. The Deepwater Horizon spill was predicted to have catastrophic consequences for nearshore fishes, but field studies indicate resilience in populations and... more
Oil spills threaten the structure and function of ecological communities. The Deepwater Horizon spill was predicted to have catastrophic consequences for nearshore fishes, but field studies indicate resilience in populations and communities. Previous research indicates many marsh fishes exhibit avoidance of oil contaminated areas, representing one potential mechanism for this resilience. Here, we test whether prior oil exposure of Gulf killifish Fundulus grandis alters this avoidance response. Using choice tests between unoiled and oiled sediments at one of three randomized concentrations (low: 0.1 L oil m−2, medium: 0.5 L oil m−2, or high: 3.0 L oil m−2), we found that, even at low prior exposure levels, killifish lose recognition of oiled sediments compared to control, unexposed fish. Preference for unoiled sediments was absent across all oil concentrations after oil exposure, and some evidence for preference of oiled sediments at high exposure was demonstrated. These results high...
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Abstract Global loss of submerged aquatic vegetation (SAV) and associated ecosystem function has prompted an interest in SAV revegetation, particularly where underlying stressors such as nutrient enrichment are mitigated, yet natural... more
Abstract Global loss of submerged aquatic vegetation (SAV) and associated ecosystem function has prompted an interest in SAV revegetation, particularly where underlying stressors such as nutrient enrichment are mitigated, yet natural recruitment remains low. Typically, SAV is hand-planted, but alternative reliable and practically scalable SAV planting techniques are needed. In mesocosms, we evaluated five planting techniques: 1) hand planting, anchoring using 2) fishing weights and 3) plaster blocks, and sediment-added methods using 4) peat pots and 5) burlap-wraps (“burritos”). Anchoring and sediment-added techniques were also field evaluated at four locations within a single lake. In mesocosms, all techniques effectively established two common North American SAV species, Vallisneria americana and Potamogeton illinoensis. Sediment-added techniques had species-specific benefits, e.g. burritos produced taller Vallisneria leaves, and greater Potamogeton biomass, while peat pots encouraged rapid Vallisneria shoot production. However, no treatment was universally beneficial across all growth metrics. In the field, all techniques were effective at two sites, but at two other sites, no techniques were successful. Results show that under favorable mesocosm and field conditions, all techniques promote establishment; however, subtle differences in technique-driven plant traits (height, density, nutrients) suggest that under specific environmental conditions, some techniques may be more favorable. Also, no technique offers practical advantages in every scenario, but each offers situation-specific advantages. Guidance emerging from this work is that all techniques are potentially effective, but small-scale tests in site-specific restoration scenarios, along with consideration of feasibility constraints, are recommended to inform large-scale plantings.
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Submerged aquatic vegetation has numerous benefits for aquatic ecosystems, from improving water quality to providing important habitat that supports a diverse food web. This new 6-page publication of the UF/IFAS Department of Soil and... more
Submerged aquatic vegetation has numerous benefits for aquatic ecosystems, from improving water quality to providing important habitat that supports a diverse food web. This new 6-page publication of the UF/IFAS Department of Soil and Water Sciences describes the breadth of options available to managers who wish to plant SAV at new locations. Because all methods have both benefits and drawbacks, and because all planting locations have different (often unknown) challenges for plant survival, managers may choose to try multiple methods to increase the likelihood for success. Written by Laura Reynolds, Carrie Reinhardt Adams, Enrique Latimer, Charles W. Martin, Christine Rohal, and Jodi Slater.https://edis.ifas.ufl.edu/ss685
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The 2010 Deepwater Horizon (DwH) oil spill in the Gulf of Mexico discharged ~3.19 million barrels of oil into Gulf waters, making it one of the largest marine disasters in history in terms of volume. We report on the results of a study to... more
The 2010 Deepwater Horizon (DwH) oil spill in the Gulf of Mexico discharged ~3.19 million barrels of oil into Gulf waters, making it one of the largest marine disasters in history in terms of volume. We report on the results of a study to assess oil impacts to coastal fishes and invertebrates. Using two-decades of fisheries-independent data in coastal Alabama and Mississippi, we document variability following both natural and anthropogenic disturbances from two periods pre-DwH (1997-2001 and 2007-2009), one intra-spill period for acute DwH effects (2010-2012) and one period post-spill for chronic, longer-term impacts (2014-2017). Results indicated significant changes to community structure, relative abundance, and diversity in the intra-spill period. Causation for changes is confounded by variables such as behavioral emigration, altered freshwater inflow, death of consumers, and the mandated fishery closure. Results highlight the need for long-term, comprehensive monitoring/observing systems to provide adequate background for assessing future disturbances.
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Vegetated habitats provide numerous benefits to nekton, including structural refuge from predators and food sources. However, the sensory mechanisms by which fishes locate these habitats remain unclear for many species, especially when... more
Vegetated habitats provide numerous benefits to nekton, including structural refuge from predators and food sources. However, the sensory mechanisms by which fishes locate these habitats remain unclear for many species, especially when environmental conditions (such as increased turbidity) are unfavorable for visual identification of habitats. Here, a series of laboratory experiments test whether three species of adult fish (golden topminnow Fundulus chrysotus Günther 1866, sailfin molly Poecilia latipinna Lesueur 1821, and western mosquitofish Gambusia affinis Baird and Girard 1853) use plant chemical cues to orient to one of two habitats [hydrilla Hydrilla verticillata (L.f.) Royle or water hyacinth Eichhornia crassipes (Mart.) Solms]. First, experiments in aquaria were conducted offering fish a choice of the two habitats to determine preference patterns. Next, a two-channel flume, with each side containing flow originating in one of the two habitats, was used to determine whether preferences were still exhibited when fish could only detect habitats through olfactory means. While patterns among the three fish species tested here were variable, results did indicate consistent habitat preferences despite the lack of cues other than olfactory, suggesting that these organisms are capable of discriminating habitats via chemical exudates from plants. As such, olfactory mechanisms likely provide vital information about the surrounding environment and future work should be directed at determining how anthropogenic inputs such as eutrophication and sediment runoff affect the physiology of these sensory capabilities.
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Fundulus grandis (Baird and Girard), the Gulf Killifish, is an abundant species throughout the marshes of the northern Gulf of Mexico. Its wide distribution and high site fidelity makes it an ideal indicator species for brackish and salt... more
Fundulus grandis (Baird and Girard), the Gulf Killifish, is an abundant species throughout the marshes of the northern Gulf of Mexico. Its wide distribution and high site fidelity makes it an ideal indicator species for brackish and salt marshes, which experience a variety of anthropogenic disturbances. Despite the ecological, commercial, and scientific importance of F. grandis, age determination methods have not been validated and little is known of its growth pattern. By combining a tag-recapture study with a chemical marker to stain otoliths, we validated an ageing method for F. grandis adults (49–128 mm TL) using whole sagittal otoliths and determined growth rates of recaptured individuals in winter (n = 58) and summer (n = 36) in Louisiana. Mean somatic growth in length was significantly greater during the winter (0.085 mm d−1) than summer (0.054 mm d−1). In contrast, mean otolith growth was significantly greater in summer (1.37 μm d−1) than winter (0.826 μm d−1). The uncoupling of somatic and otolith growth may be primarily attributed to warm summer temperatures, which led to enhanced otolith growth while simultaneously reducing somatic growth. Fundulus grandis was aged to a maximum of 2.25 years. The parameters of the von Bertalanffy growth model were estimated as: L∞ = 87.27 mm, k = 2.43 year−1, and t0 = −0.022. These findings reveal essential age and growth information for F. grandis and provide a benchmark to evaluate responses to environmental disturbances.
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Research Interests: Botany, Marine Biology, Environmental Science, Wetlands, Marine Ecology, and 13 moreToxicology, Wetland Ecology, Ecology of Coastal Systems, Medicine, Multidisciplinary, Oil Spill, Estuarine Ecology, Oil Spills in the Marine Environment, Seagrass ecology, BP/Deepwater Horizon Oil Spill, PLoS one, Emerging Pollutants In Water, and Geologic Sediments
ABSTRACT One of the most successful groups of invasive consumers worldwide is freshwater snails of the family Ampullariidae, including Pomacea maculata, yet little is known about snail survival and growth in the range of conditions found... more
ABSTRACT One of the most successful groups of invasive consumers worldwide is freshwater snails of the family Ampullariidae, including Pomacea maculata, yet little is known about snail survival and growth in the range of conditions found in estuarine ecosystems. Here, we provide an experimental assessment of P. maculata survivability in estuarine conditions, documenting: (1) egg susceptibility to tidal inundation (2) salinity tolerance of snails, and (3) salinity effects on hatchling growth. Results indicate that estuarine conditions will not limit apple snail colonization in oligohaline and mesohaline reaches of estuaries, with eggs remaining viable when exposed to periodic inundations typical of a tidal regime and modest, albeit reduced, growth and survival at moderate salinities (5 and 10 ppt). For this reason, rapid detection and eradication of P. maculata in estuarine areas is needed to avoid the invasion of snails in these vital, productive environments.
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Prey naiveté has been hypothesized to be one of the major driving forces behind population declines following the introduction of novel predators or release of inexperienced prey into predator rich environments. In these cases, naïve prey... more
Prey naiveté has been hypothesized to be one of the major driving forces behind population declines following the introduction of novel predators or release of inexperienced prey into predator rich environments. In these cases, naïve prey may lack sufficient antipredator behavior and, as a result, suffer increased mortality. Despite this, some evidence suggests that many prey utilize a generalized response to predators. Here, the naiveté hypothesis is tested using a predator-prey pair sharing an evolutionary history: the red swamp crayfish (Procambarus clarkii Girard, 1852) and largemouth bass (Micropterus salmoides Lacépède, 1802). Using farm-reared, naïve crayfish and wild-caught, experienced individuals, laboratory experiments demonstrated that naïve, farmed crayfish lack behavioral responses to chemical cues from bass, both in terms of movement and use of structural refuge. In contrast, experienced crayfish responded strongly to the same cues. In a subsequent field tethering exp...
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Estuarine ecosystem balance typically relies on strong food web interconnectedness dependent on a relatively low number of resident taxa, presenting a potential ecological vulnerability to extreme ecosystem disturbances. Following the... more
Estuarine ecosystem balance typically relies on strong food web interconnectedness dependent on a relatively low number of resident taxa, presenting a potential ecological vulnerability to extreme ecosystem disturbances. Following the Deepwater Horizon (DwH) oil spill disaster of the northern Gulf of Mexico (USA), numerous ecotoxicological studies showed severe species-level impacts of oil exposure on estuarine fish and invertebrates, yet post-spill surveys found little evidence for severe impacts to coastal populations, communities, or food webs. The acknowledgement that several confounding factors may have limited researchers’ abilities to detect negative ecosystem-level impacts following the DwH spill drives the need for direct testing of weathered oil exposure effects on estuarine residents with high trophic connectivity. Here, we describe an experiment that examined the influence of previous exposure to four weathered oil concentrations (control: 0.0 L oil m−2; low: 0.1 L oil m...
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Estuarine ecosystem balance typically relies on strong food web interconnectedness dependent on a relatively low number of resident taxa, presenting a potential ecological vulnerability to extreme ecosystem disturbances. Following the... more
Estuarine ecosystem balance typically relies on strong food web interconnectedness dependent on a relatively low number of resident taxa, presenting a potential ecological vulnerability to extreme ecosystem disturbances. Following the Deepwater Horizon (DwH) oil spill disaster of the northern Gulf of Mexico (USA), numerous How to cite this article McDonald AM, Martin CW, Rieucau G, Roberts BJ. 2022. Prior exposure to weathered oil influences foraging of an ecologically important saltmarsh resident fish.
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Established populations of introduced Pomacea maculata, a highly fecund, large species of apple snail native to South America, now occur throughout southeast Asia, in Spain and extensively across the southern United States. Substantial... more
Established populations of introduced Pomacea maculata, a highly fecund, large species of apple snail native to South America, now occur throughout southeast Asia, in Spain and extensively across the southern United States. Substantial research on nonnative apple snails takes place in Southeast Asia and has frequently identified apple snails as P. canaliculata. That these Asian populations represent at least two Pomacea species, P. canaliculata and P. maculata, has been confirmed through anatomical and genetic evidence. However, the two species are often still confused because of their similar shell morphologies and life history traits. This contribution reviews the distribution, life history, ecology and management of P. maculata introduced to the southern USA. So
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Climate change is altering naturally fluctuating environmental conditions in coastal and estuarine ecosystems across the globe. Departures from long-term averages and ranges of environmental variables are increasingly being observed as... more
Climate change is altering naturally fluctuating environmental conditions in coastal and estuarine ecosystems across the globe. Departures from long-term averages and ranges of environmental variables are increasingly being observed as directional changes [e.g., rising sea levels, sea surface temperatures (SST)] and less predictable periodic cycles (e.g., Atlantic or Pacific decadal oscillations) and extremes (e.g., coastal flooding, marine heatwaves). Quantifying the short-and long-term impacts of climate change on tidal marsh seascape structure and function for nekton is a critical step toward fisheries conservation and management. The multiple stressor framework provides a promising approach for advancing integrative, cross-disciplinary research on tidal marshes and food web dynamics. It can be used to quantify climate change effects on and interactions between coastal oceans (e.g., SST, ocean currents, waves) and watersheds (e.g., precipitation, river flows), tidal marsh geomorphology (e.g., vegetation structure, elevation capital, sedimentation), and estuarine and coastal nekton (e.g., species distributions, life history adaptations, predator-prey dynamics). However, disentangling the cumulative impacts of multiple interacting stressors on tidal marshes, whether the effects are additive, synergistic, or antagonistic, and the time scales at which they occur, poses a significant research challenge. This perspective highlights the key physical and ecological processes affecting tidal marshes, with an emphasis on the trophic linkages between marsh production and estuarine and coastal nekton, recommended for consideration in future climate change studies. Such studies are urgently needed to understand climate change effects on tidal marshes now and into the future.
Coastal salt marshes are distributed widely across the globe and are considered essential habitat for many fish and crustacean species. Yet, the literature on fishery support by salt marshes has largely been based on a few geographically... more
Coastal salt marshes are distributed widely across the globe and are considered essential habitat for many fish and crustacean species. Yet, the literature on fishery support by salt marshes has largely been based on a few geographically distinct model systems, and as a result, inadequately captures the hierarchical nature of salt marsh pattern, process, and variation across space and time. A better understanding of geographic variation and drivers of commonalities and differences across salt marsh systems is essential to informing future management practices. Here, we address the key drivers of geographic variation in salt marshes: hydroperiod, seascape configuration, geomorphology, climatic region, sediment supply and riverine input, salinity, vegetation composition, and human activities. Future efforts to manage, conserve, and restore these habitats will require consideration of how environmental drivers within marshes affect the overall structure and subsequent function for fisheries species. We propose a future research agenda that provides both the consistent collection and reporting of sources of variation in small-scale studies and collaborative networks running parallel studies across large scales and geographically distinct locations to provide analogous information for data poor locations. These comparisons are needed to identify and prioritize restoration or conservation efforts, identify sources of variation among regions, and best manage fisheries and food resources across the globe.
Vallisneria americana typically produces solitary pistillate inflorescences; however, unusual umbellate flowers have been observed in subtropical populations and are reported as rare. There are multiple hypotheses regarding the origin or... more
Vallisneria americana typically produces solitary pistillate inflorescences; however, unusual umbellate flowers have been observed in subtropical populations and are reported as rare. There are multiple hypotheses regarding the origin or cause of umbellate inflorescences-they may be relics of ancestral stocks surviving through asexual reproduction, heritable traits worthy of taxonomic recognition, or teratological specimens resulting from injury during flower formation. Through surveys of Vallisneria populations in four lakes in Central Florida, USA, we show these umbellate flowers are broadly distributed and we document their physical and reproductive traits, contrasted with solitary capsules (capsule number, capsule length and width, seed number, germination). Umbellate inflorescences were found frequently across space and time-capsules were found in three of four lakes, 40-80 % of the times flowering was observed. Umbellate inflorescences produced fewer seeds than solitary capsules, despite having 2-33 capsules per inflorescence. Seeds from umbellate capsules were viable, but germination occurred more slowly and at a lower percentage than seeds from solitary capsules. Nematodes were not detected within sampled inflorescences. Chironomid larvae were detected at a high rate (75-80 %) in umbellate capsules from two of three lakes but were not found on solitary capsules, suggesting they may be a possible cause for teratological growth. We conclude umbellate inflorescences are broadly distributed in Central Florida lakes and, while not sterile, they may have reproductive costs. Further study is needed to fully evaluate the cause of umbellate formation, population-level effects, and their range within Vallisneria americana.
Submerged aquatic vegetation (SAV) improves environmental conditions by acting as a sediment stabilizer and nutrient retention tool; therefore, reintroduction of SAV is a common freshwater restoration goal. Initial plant establishment is... more
Submerged aquatic vegetation (SAV) improves environmental conditions by acting as a sediment stabilizer and nutrient retention tool; therefore, reintroduction of SAV is a common freshwater restoration goal. Initial plant establishment is often difficult in suboptimal conditions, and planting material with specific traits may increase establishment rates. Here we evaluate the variability in plant traits based on collection location. We find consistent differences in traits of plants collected from different natural water bodies, and those differences persist in plants grown from seeds under common garden greenhouse conditions-presumably because of genetic differentiation. In three separate mesocosm experiments, we tested the interactive impacts of collection location and environmental condition (control conditions, reduced light, elevated nutrients, or a combination of reduced light and elevated nutrients) on plant reproduction and on traits that might indicate future restoration success (plant height, number of leaves, and rhizome diameter). In most cases, plant traits at the end of the experiments varied by collection location, environmental condition, and an interaction between the two. The best performing plants also depended on response variable (e.g., plant height or number of new shoots produced). Together these results suggest that unpredictable environmental conditions at restoration sites will make selection of a single high-performing plant source difficult, so we suggest incorporating a diverse set of collection locations to increase the probability of incorporating desirable traits.