Charles Martin | University of South Alabama (original) (raw)
Papers by Charles Martin
Frontiers in Environmental Science
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can provide ... 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...
Marine Ecology Progress Series
Seagrass meadows provide greater predator refuge and resource availability than unvegetated habit... 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...
Reviews in Fish Biology and Fisheries
produce active (i.e., intentional) sounds. Active fish sound production is geographically and tax... 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.
PeerJ
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase... 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...
Herpetological Conservation and Biology, 2022
The Diamond-backed Terrapin (Malaclemys terrapin) inhabits coastal islands along the Gulf coast o... 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.
Reviews in Fish Biology and Fisheries, 2022
produce active (i.e., intentional) sounds. Active fish sound production is geographically and tax... 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.
Restoration Ecology, 2022
Established natural oyster reefs historically provide a three-dimensionally complex habitat utili... 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.
PeerJ, 2022
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase... 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.
Frontiers in Environmental Science, 2023
Ecological Informatics, 2023
Many fish species use active sound production for communication in numerous behaviors. Additional... 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.
Frontiers in Environmental Science, 2022
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can provide ... 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.
Marine Ecology Progress Series, 2019
Frontiers in Marine Science, 2022
A warming climate is driving the poleward expansion of tropical, subtropical, and temperate plant... 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.
Science, 2020
Salt marsh ecosystems and the seascapes in which they are embedded serve as critical habitats for... 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.
Estuaries and Coasts, 2021
Temperatures are increasing globally and causing species-specific geographic range expansions. In... 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.
Limnology and Oceanography, 2021
Estuaries and Coasts, 2021
Small variations in environmental parameters can substantially alter species composition, but the... 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.
Estuaries and Coasts, 2020
Frontiers in Environmental Science
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can provide ... 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...
Marine Ecology Progress Series
Seagrass meadows provide greater predator refuge and resource availability than unvegetated habit... 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...
Reviews in Fish Biology and Fisheries
produce active (i.e., intentional) sounds. Active fish sound production is geographically and tax... 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.
PeerJ
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase... 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...
Herpetological Conservation and Biology, 2022
The Diamond-backed Terrapin (Malaclemys terrapin) inhabits coastal islands along the Gulf coast o... 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.
Reviews in Fish Biology and Fisheries, 2022
produce active (i.e., intentional) sounds. Active fish sound production is geographically and tax... 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.
Restoration Ecology, 2022
Established natural oyster reefs historically provide a three-dimensionally complex habitat utili... 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.
PeerJ, 2022
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase... 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.
Frontiers in Environmental Science, 2023
Ecological Informatics, 2023
Many fish species use active sound production for communication in numerous behaviors. Additional... 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.
Frontiers in Environmental Science, 2022
Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can provide ... 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.
Marine Ecology Progress Series, 2019
Frontiers in Marine Science, 2022
A warming climate is driving the poleward expansion of tropical, subtropical, and temperate plant... 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.
Science, 2020
Salt marsh ecosystems and the seascapes in which they are embedded serve as critical habitats for... 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.
Estuaries and Coasts, 2021
Temperatures are increasing globally and causing species-specific geographic range expansions. In... 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.
Limnology and Oceanography, 2021
Estuaries and Coasts, 2021
Small variations in environmental parameters can substantially alter species composition, but the... 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.
Estuaries and Coasts, 2020