Lutjanus Griseus Research Articles

Trophic position and prey preferences of snappers (Teleostei: Lutjanidae) in a connected bay-to-reef Caribbean system

The trophic position (TP) and proportional contribution of prey for six species of snappers were assessed at two interconnected coastal environments of the Mexican Caribbean: the mangroves of Río Huach Channel and Chetumal/Corozal Bay, and the seagrass beds of the adjacent Xcalak Reef Lagoon. This study provides a trophic scenario using stable isotopes, under the hypothesis that use of resources would vary by habitat. We evaluated the relative proportion of carbon and nitrogen of assimilated resources and TP. According to the stable isotope mixing models, snappers showed a higher consumption of secondary consumers at the expense of primary consumers. Snappers are piscivorous-invertivorous mesopredators and the most piscivorous species were Lutjanus griseus and L. jocu, which displayed a higher TP. Lutjanus griseus had a higher TP than the other snappers both in the bay and the reef lagoon, whereas Ocyurus chrysurus showed the lowest TP, with a major preference for crustaceans. Our findings revealed differences in resource use by snapper species rather than by habitat. Understanding TP and differential use of resources by snappers is key to understanding the dynamics and function of connected ecosystems to implement effective conservation and management strategies.

Recruitment of Juvenile Snapper (Lutjanidae) in the Middle Florida Keys: Temporal Trends and Fine-Scale Habitat Associations

Juvenile recruitment is a major factor in the establishment and maintenance of local population structures of coral reef fishes. An understanding of the factors that affect juvenile recruitment and survival help explain spatial and temporal patterns in adult abundance, especially of commercially and recreationally fished species. Here, we examined the distribution and juvenile recruitment of 5 snapper species: Mutton Snapper (Lutjanus analis), Lane Snapper (L. synagris), Schoolmaster (L. apodus), Gray Snapper (L. griseus), and Yellowtail Snapper (Ocyurus chrysurus) collected in 1,314 seine samples conducted between 2007 and 2019 in the Middle Florida Keys. We use a generalized linear modeling routine to assess juvenile recruitment of each species as a function of temporal, environmental, and benthic habitat variables. Interannual variability in juvenile recruitment ranged between 2 and 15—fold differences in mean predicted abundance between the highest and lowest producing years by species. Predicted recruitment varied dramatically by species in 2010 following a historic cold spell in south Florida. Three of the 5 species (Lane Snapper, Yellowtail Snapper, and Schoolmaster) exhibited the lowest observed yearly recruitment in that year, while Gray Snapper recruitment peaked. For all species, recruitment indices exhibited strong seasonal trends with peak abundances observed in the fall. Aquatic vegetation type, aquatic vegetation cover, distance from shore, and water temperature were the most important predictors of abundance. Results of this study highlight species—specific preferences for settlement habitat, demonstrate the importance of local—scale recruitment processes, and provide updated, management—relevant juvenile abundance indices for shallow water snapper in the Middle Florida Keys.

Restored oyster reefs and living shorelines can augment predator trophic dynamics

Coastal habitat loss has led to declines in many higher trophic level predators. These declines can be mitigated through habitat restoration, which putatively enhances predator populations and trophic dynamics by creating foraging opportunities in reestablished habitat, but this lacks empirical support. Here, we assess the prediction restored coastal habitat supports sportfish feeding relationships similar to natural habitat, at restored oyster reefs (Crassostrea virginica) and living shoreline habitats in Florida, U.S.A. Stable isotopes and gut contents were analyzed from young sportfish (i.e. predatory fish targeted by anglers) collected at control and restored sites for up to 3 years. The influence of habitat features, predator size, and prey availability on carbon and nitrogen isotope values were examined using a model species (mangrove/gray snapper [Lutjanus griseus]). In summary, sportfish species had distinct isotopic values, consuming similar prey but in different proportions between habitats. Prey abundance and richness, and reef height were influential predictors of L. griseus stable isotope values, with restored reefs contributing to their diet more than controls according to Bayesian mixing models. The trophic niche area of L. griseus and their predominant prey achieved trophic equivalence between restored and natural oyster reefs within 1 year following restoration. Stabilized living shorelines attained trophic equivalency to natural shorelines, but may take longer to accrue prey for some species. These findings generate fundamental ecological knowledge and actionable science, including targets, timelines, and indicator species, that natural resource managers and restoration practitioners can use to assess trophic structure and success of coastal habitat restoration.

What controls home range relocations by estuarine fishes downstream from watersheds with altered freshwater flow?

We tracked locations of three fish species in two bays with differing hydrology in SW Florida in 2018–2020 to test the hypotheses about fish residency, movements, and environmental variables. Due to extensive watershed modification, one bay receives less freshwater and the other receives more relative to natural conditions. Home range duration differed for gray snapper (54 ± 6 days), red drum (132 ± 39), and goliath grouper (226 ± 63). Distances between relocation movements were similar for gray snapper and red drum (~ 1.2 km), but farther for goliath grouper (2.3 ± 0.3 km). Relocations were primarily seaward for gray snapper (83%) but varied for the other species. Home range duration related to age for goliath grouper (< 100 days for 1–1.5-year-olds, 300–425 days for 4–4.5-year-olds). Generalized additive models marginally related probability of gray snapper relocating to salinity and temperature whereas relocations of the other species occurred during all environmental conditions. Movement simulations lacking environmental cues produced similar emigration patterns as observed in tagged fish. Overall, results suggest that movements here are not strongly linked to environmental conditions, will be resilient to watershed restoration that should moderate salinity, and have implications for understanding the impacts of localized depletion due to recreational fishing.

Tropical estuarine ecosystem change under the interacting influences of future climate and ecosystem restoration.

One of the largest restoration programs in the world, the Comprehensive Everglades Restoration Plan (CERP) aims to restore freshwater inputs to Everglades wetlands and the Florida Bay estuary. This study predicted how the Florida Bay ecosystem may respond to hydrological restoration from CERP within the context of contemporary projected impacts of sea-level rise (SLR) and increased future temperatures. A spatial-temporal dynamic model (Ecospace) was used to develop a spatiotemporal food web model incorporating environmental drivers of salinity, salinity variation, temperature, depth, distance to mangrove, and seagrass abundance and was used to predict responses of biomass, fisheries catch, and ecosystem resilience between current and future conditions. Changes in biomass between the current and future scenario suggest a suite of winners and losers, with many estuarine species increasing in both total biomass and spatial distribution. Notable biomass increases were predicted for important forage species, including bay anchovy (+32%), hardhead halfbeak (+19%), and pinfish (+31%), while decreases were predicted in mullet (-88%), clupeids (-55%), hardhead silverside (-15%), mojarras (-117%), and Portunid crabs (-16%). Increases in sportfish biomass included the angler-preferred spotted seatrout (+9%), red drum (+10%), and gray snapper (+8%), while decreases included sheepshead (-40%), Atlantic tarpon (-73%), and common snook (-507%). Ecosystem resilience and fisheries catch of angler-preferred species were predicted to improve in the future scenario in total, although a localized decline in resilience predicted for the Central Region may warrant further attention. Our results suggest the Florida Bay ecosystem is likely to achieve restoration benefits in spite of, and in some cases facilitated by, the projected future impacts from climate change due to the system's shallow depth and detrital dominance. The incorporation of climate impacts into long-term restoration planning using ecosystem modeling in similar systems facing unknown futures of SLR, warming seas, and shifting species distributions is recommended.

Evidence of ontogenetic partitioning of restored coastal habitat by a generalist sportfish

Coastal and estuarine habitats that provide crucial nursery areas for many economically and ecologically important fish species are in decline. Restoration of benthic habitats can improve fish populations, biomass, and feeding opportunities, but there is limited research on how restoration impacts growth and survival with ontogeny. To address this knowledge gap, here we examine the biometrics (size, biomass, and body condition), recruitment, size structure, and trophic shifts of a sportfish (mangrove snapper, Lutjanus griseus) at restored oyster reefs and stabilized living shorelines to better understand how fish use restored habitats as they grow. Biomass and body condition of L. griseus juveniles and subadults, and post‐settlement recruitment, at restored/stabilized sites was similar, and in some cases greater than natural sites, correlating with benthic habitat, reef location, and lunar phase at oyster reefs. Living shorelines exhibited greater recruitment potential, while oyster reefs supported more juveniles and subadults, as evidenced by differences in fish size and biomass between habitats. Dietary overlap implies subadult L. griseus likely foraged across habitats more than juveniles, while there was greater diet similarity within habitats. Furthermore, ontogenetic shifts also occurred within oyster reef habitats, highlighting the importance of quality habitat to support various sportfish life stages, which can be achieved through restoration. These findings suggest life history attributes can be indicators of habitat restoration success, and specifically provide actionable science to guide the development of more effective strategies for restoring inshore nursery habitats and thus augment production of offshore reef fisheries.

Insight into the trophic niche and prey contribution in the diet of Lutjanus griseus (Linnaeus, 1758) captured by artisanal fishing fleet in the central and southwest Gulf of Mexico

Lutjanus griseus is a common species for fisheries of the Gulf of Mexico, and it is an effective vehicle to transport energy from low to top trophic levels in the ecosystem. The management of fish populations is based on the modeling and prediction of abundances. To accomplish this, trophic ecology results allow the understanding of habitat use and population expansions. To increase the knowledge in the trophic ecology of L. griseus, this study described its trophic niche, diet composition, and the prey contribution in the formation of muscle tissue. Results showed that the trophic niche in Veracruz was wider than in Campeche, this related to the consumption of prey in different habitats, coral reefs areas in Veracruz and seagrass beds in Campeche. According to the δ13C y δ15N values, in both regions the crustaceans were the most important group in the contribution of muscle tissue, however, it contrasted with the stomach content results, which suggested that the diet in Campeche was mainly composed of crustaceans, and in Veracruz of fishes. This difference could be related to the snapper’s movements, as they can be found in sea bottoms covered with seagrass, with high abundance of crustaceans, and sea bottoms composed of coral reefs with high diversity of fishes and other preys. Results highlight the generalist and opportunistic feeding strategy of L. griseus, this strategy allowed its population expansion to the north, consuming the available food source in the different habitats it occupied.

Resource Partitioning of Sympatric Lutjanids in the Northern Gulf of Mexico Using Stable Isotope Analysis

Lutjanid snappers are ubiquitous at reef sites in the northern Gulf of Mexico (Gulf), but the degree of niche overlap and basal resource utilization is unknown for most species. Muscle tissue for stable isotope analysis was opportunistically sampled from red snapper (Lujanus campechanus), gray snapper (Lutjanus griseus), lane snapper (Lutjanus synagris), and vermilion snapper (Rhomboplites aurorubens) recreational catches across the northern Gulf. A Bayesian mixing model used to compare resource utilization indicated that Lutjanids occupy niches with varying degrees of overlap among regions but maintain a consistent hierarchy in isotopic composition. Scale shifts among regions were likely due to differences in riverine outflow, nitrogen fixation, and anoxic zones that alter prey abundance or isotopic δ15N ratios. All four Lutjanid species had high percent contributions from particulate organic matter and benthic microalgae with little contribution by macroalgae to any species in any region. Ontogenetic shifts in stable isotope values were observed in most species indicating that size plays an important role in avoiding niche overlap due to intense competition for high-value prey items among congeners at isolated reef sites. Diet specialization is modest but likely plays an important role in avoiding complete niche overlap.

De novo transcriptomes for two species of snappers from the Western Atlantic (Lutjanus griseus and Lutjanus synagris).

Transcriptomes are appropriate resources for studying species that lack sequenced genomes, as they can serve as references for a broad suite of genetic applications, including: phylogenetic assessments, population genomics, and evaluate responses to environmental fluctuations. Here, we present the transcriptomes of two species of marine fishes of commercial and ecological relevance in the Western Atlantic: Lutjanus griseus and L. synagris. This project represents a step forward on developing genomic resources for important species of the Atlantic Ocean.

Reproduction of grey snapper (Teleostei: Lutjanidae) in the southern Gulf of Mexico

Snappers exhibit reproductive trait plasticity in response to habitat distribution. Lutjanus griseus is among the most economically important snappers in the western Central Atlantic but has received limited study in the region. Data on the reproductive biology of the L. griseus population were collected on the continental shelf of the Yucatan Peninsula, Mexico. Over a nineteen-month period, 1236 specimens were captured monthly in three Yucatan artisanal fishing fleet operational areas. Data were grouped by month to generate an annual analysis. Individual sex and maturation status were identified by gonad histology. Median size did not differ between females (33.2 cm fork length [FL]) and males (33.3 cm FL), and the sex ratio was balanced (F:M=0.98:1.00). Size at maturity was 24.2 cm FL for females (38% of maximum size reported for the species) and 22.8 cm FL for males (36% of maximum size), and the spawning season ran from May to September. The results confirm that this population exhibits the typical reproductive pattern of snappers distributed on continental shelves or in shallow water areas and provide critical data for stock assessment and implementation of management measures for L. griseus stock in the southern Gulf of Mexico.

Parasite Community Analysis of The Gray Snapper Lutjanus Griseus (Perciformes,Lutjanidae) in a Tropical Region of The Southern Gulf of Mexico.

SummaryThe gray snapper Lutjanus griseus is a commercially important fish species along its distribution range in the western Atlantic Ocean. However, despite its importance, there is still little knowledge about its parasitic fauna for the Mexican coasts of the Gulf of Mexico. The aims of this research were to generate a list of the parasitic fauna present in juvenile gray snapper L. griseus from a coastal lagoon located in southeastern Mexico, to evaluate the infection levels of parasites and to determine the relationship between the abundance of parasites and the fish size and condition factor. Samples of L. griseus (12 – 29.2 mm) were obtained in two periods of the year (dry and rainy seasons) to examine the intra-annual variability of its parasitic fauna. A total of 17 parasite species were recorded belonging to six taxonomic groups (Myxozoa, Monogenea, Digenea, Cestoda, Nematoda and Acanthocephala). The highest levels of infection (abundance, prevalence and intensity of infection) were found for the monogeneans Euryhaliotrema griseus and Euryhaliotrema fastigatum. There were no significant correlations between the total abundance of parasites and the fish condition and size (total length) in not any of the two seasons studied, suggesting that the body size and the biological condition index of the host did not directly influence the abundance of parasites in early life stages of L. griseus. Moreover, the species of parasites found that could be zoonotic for humans through the consumption of raw or inadequately cooked fish were the nematodes Contracaecum sp. type 1, Contracaecum sp. type 2, Cucullanus pargi and Pseudoterranova sp. The presence of the monogeneans E. griseus and E. fastigatum was also highlighted because these ectoparasite species are known to cause harm to fish under culture systems. All the parasite species found in this study, except nematodes, were new records of geographic distribution.

Underwater Video as a Tool to Quantify Fish Density in Complex Coastal Habitats

Habitat loss is a serious issue threatening biodiversity across the planet, including coastal habitats that support important fish populations. Many coastal areas have been extensively modified by the construction of infrastructure such as ports, seawalls, docks, and armored shorelines. In addition, habitat restoration and enhancement projects often include constructed breakwaters or reefs. Such infrastructure may have incidental or intended habitat values for fish, yet their physical complexity makes quantitatively sampling these habitats with traditional gears challenging. We used a fleet of unbaited underwater video cameras to quantify fish communities across a variety of constructed and natural habitats in Perdido and Pensacola Bays in the central northern Gulf of Mexico. Between 2019 and 2021, we collected almost 350 replicate 10 min point census videos from rock jetty, seawall, commercial, public, and private docks, artificial reef, restored oyster reef, seagrass, and shallow sandy habitats. We extracted standard metrics of Frequency of Occurrence and MaxN, as well as more recently developed MeanCount for each taxon observed. Using a simple method to measure the visibility range at each sampling site, we calculated the area of the field of view to convert MeanCount to density estimates. Our data revealed abundant fish assemblages on constructed habitats, dominated by important fisheries species, including grey snapper Lutjanus griseus and sheepshead Archosargus probatocephalus. Our analyses suggest that density estimates may be obtained for larger fisheries species under suitable conditions. Although video is limited in more turbid estuarine areas, where conditions allow, it offers a tool to quantify fish communities in structurally complex habitats inaccessible to other quantitative gears.

Distribution, Maturity, Age and Growth of Gray Snapper (Lutjanus griseus) in the Northwestern Gulf of Mexico

Recent population expansion of Gray Snapper, Lutjanus griseus, in the northern Gulf of Mexico is driving increasing catch in the recreational fishery in Texas. We assessed long—term trends in distribution and abundance of Gray Snapper in Texas using fishery—dependent and fishery—independent data collected by the Texas Parks and Wildlife Department in the years 1980 — 2019. Boosted regression trees (BRT) were used to evaluate factors (water quality, season, depth, bay and inlet distance) driving Gray Snapper presence in fishery—independent samples of juveniles (seines) and subadults (gill nets) found in estuaries. Estuarine Gray Snapper were subsequently sampled from gill nets, and otolith age and gonad development were evaluated microscopically to assess patterns of age, growth, and maturity. Increasing Gray Snapper abundance in Texas was coupled with expansion of the population age structure in comparisons before and after 1993. Gray Snapper juveniles and subadults encountered in Texas estuaries are generally associated with lower bays and offshore passes, and are more common in the late summer/early fall. Comparison of size (total length in mm) of recreational catch inshore versus offshore suggests that mature adults recruit to offshore habitats around 409 mm TL, or around 3 years old, which is approximately coincident with the onset of sexual maturity. Increasing abundance coupled with an expanding age structure of Gray Snapper in Texas have co—occurred with increasing winter temperatures over time. Population expansion could be facilitated by management measures that improve overwinter survival of juveniles and subadults in estuaries prior to offshore recruitment.

Loss of suitable ocean habitat and phenological shifts among grouper and snapper spawning aggregations in the Greater Caribbean under climate change

Phenological shifts have been observed among marine species due to climate change. Modeling changes in fish spawning aggregations (FSAs) under climate change can be useful for adaptive management, because it can allow managers to adjust conservation strategies in the context of specific life history and phenological responses. We modeled effects of climate change on the distribution and phenology of Caribbean FSAs, examining 4 snapper and 4 grouper species. An ecological niche model was used to link FSAs with environmental conditions from remote sensing and project FSA distribution and seasonality under RCP8.5. We found significant differences between groupers and snappers in response to warming. While there was variation among species, groupers experienced slight delays in spawning season, a greater loss of suitable ocean habitat (average loss: 72.75%), and poleward shifts in FSA distribution. Snappers had larger shifts towards earlier phenology, with a smaller loss of suitable ocean habitat (average loss: 24.25%), excluding gray snapper, which gained habitat. Snappers exhibited interspecific variability in latitudinal distribution shifts. Snapper FSAs appeared more resilient to climate change and occupy wider and warmer spawning temperature ranges, while groupers prefer cooler spawning seasons. Consequently, groupers may lose more suitable ocean spawning habitat sooner due to climate change. When comparing species, there were trade-offs among climate change responses in terms of distribution shifts, phenology changes, and declines in habitat suitability. Understanding such trade-offs can help managers prioritize marine protected area locations and determine the optimal timing of seasonal fishing restrictions to protect FSAs vulnerable to fishing pressure in a changing climate.

Trophic resource partitioning among four sympatric lutjanid species in the southern Mexican Caribbean Sea

ABSTRACT Snappers are marine fishes that inhabit reef ecosystems and have a wide distribution throughout tropical and subtropical waters of the Atlantic, Indian and Pacific Oceans. These species are resources of economic importance, there is a lack of biological and ecological knowledge about these species in the studied area, and their meat is highly valued for human consumption. To contribute to the ecological knowledge, this work reports on the feeding habits of four species of snapper: Lutjanus synagris, Lutjanus griseus, Lutjanus analis and Lutjanus apodus, through the identification of stomach contents and a similarity analysis for the diets. Results showed that the most important prey items were crustaceans. Differences were found in the consumption of specific prey: Portunus were mainly consumed by L. griseus; Cronius was consumed by L. apodus; and Pitho was consumed by L. analis and L. synagris. Identification of prey species to genus and species levels allowed the characterization of the feeding habits of these sympatric species and highlighted the need for research programmes focused on crustaceans that guarantee their availability and abundance in the ecosystem.

Spatial and Temporal Influences of Nearshore Hydrography on Fish Assemblages Associated with Energy Platforms in the Northern Gulf of Mexico

In 2013–2014, remote video and diver surveys documented fish assemblages around 150 small oil platforms in nearshore federal waters off the entire Louisiana coast (≤ 18 m depth). Results were used to evaluate ecological processes driving differences in fish abundance and assemblages associated with platforms. The nearshore zone was characterized by high spatial and temporal environmental heterogeneity. Surveys documented 55 species of platform-associated fishes. Twenty-nine species were partially or wholly represented by young-of-the-year (YOY) or age 1–2 juveniles, including red, gray, and lane snapper (Lutjanus campechanus, Lutjanus griseus, and Lutjanus synagris), greater amberjack (Seriola dumerili), and gag grouper (Mycteroperca microlepis). Assemblages were compared among three coastal regions with different hydrography due to interactions between river discharge and bathymetry. Assemblage composition near platforms varied in a region × year interaction associated with inter-annual differences in river discharge and coastal distribution of Sargassum drifts. The probability of YOY L. campechanus occurrence increased with bottom DO saturation (1.40–124.3%) from 0.15 to 0.72. The probability of YOY L. synagris and M. microlepis respectively decreased and increased with depth (5.61–16.76 m) from 0.81 to 0.05 and from 0.03 to 0.68. The results show that fish assemblages around platforms in the nearshore zone experienced substantial inter-regional and inter-annual differences that were driven by hydrographic and recruitment variability. Platforms also provided suitable reef habitat for juvenile fishes in areas that experience widespread bottom water hypoxia and large freshwater inflows, highlighting the importance of nearshore platforms as nursery locations for juvenile fishes that represent a variety of early life-history strategies.

Feeding habits variability of Lutjanus synagris and Lutjanus griseus in the littoral of Campeche, Mexico: an approach of food web trophic interactions between two snapper species

The study of the feeding habits variability (spatial and temporal scales) allows us to evaluate the trophic interactions between species, thus, the short and long-term effects of the removal of different species by the presence of different phenomena. In this study, we carried out stable isotope (δ13C and δ15N) and stomach content analyses to infer the trophic linkages between two snapper species (Lutjanus synagris and Lutjanus griseus) captured in the littoral of Campeche, Mexico. In total, 781 specimens were collected (528 L. synagris and 253 L. griseus) and based on relative importance index [%PSIRI] both snapper species consumed based on the prey-specific index of relative importance (PSIRI), Penaeidae family (PSIRI = 23.41%) was the most important species in the diet of Lutjanus synagris, while Callinectes sapidus (PSIRI = 21.45%) was the primary prey of Lutjanus griseus. The isotopic analyses indicated that both snapper species feed in the coastal-marine (δ15N: 10.6 to 12.1‰ and δ13C: -15.7 to -12.7‰); however, according to PERMANOVA, low diet similarity was found between snapper species (R = 0.07, P &lt; 0.01), also, significant differences was detected in the δ15N and δ13C values between L. synagris, and L. griseus. Therefore, despite both snapper species presents similar trophic positions (L. synagris: 4.2 ± 0.2; L. griseus: 3.9 ± 0.1) and feeding behavior (according to SIBER = opportunistic predators), a low trophic overlap was observed, probably associated with the differential use of habitat in the coastal zone; where L. synagris is ecologically fed in areas of seagrass, while L. griseus is probably intermittent between pasture and mangrove areas, therefore, the role of each species is crucial in the dynamics of coastal-marine ecosystems as predators and potential structuring of the populations of their prey.

Determinants of the nursery role of seagrass meadows in the sub-tropical Gulf of Mexico: inshore-offshore connectivity for snapper and grouper

Quantifying the nursery role of habitats or locations in supporting fisheries is central to understanding population-scale animal-habitat relationships, and in guiding ecosystem-based management. We assessed the nursery role of northern Gulf of Mexico seagrass meadows for gray snapper, lane snapper, and gag recruiting to Alabama’s extensive offshore reef complex. We accomplished this using broadscale juvenile trawl surveys and geochemical tags—indicative of past habitat use—stored in the otoliths of &gt;2200 fishes. These natural tags revealed that 47-61% of snapper and gag recruits to Alabama reefs originated in Florida panhandle seagrass nurseries. Seagrass meadows in Alabama and Mississippi were also important nurseries for snappers and gag, contributing 26-46% of recruits. Despite high juvenile snapper and gag catches along the extensive Chandeleur Islands, Louisiana, relatively few of those fishes recruited to Alabama’s reefs (&lt;13% of total recruits, across species), although they may have recruited to populations outside our sampling domain. Beyond the applied value of these data for resource management (i.e. interstate connectivity), our findings highlight broadscale drivers of the nursery role of juvenile habitats for coastal marine populations. These factors include: (1) juvenile habitat extent (i.e. extensive Florida panhandle meadows sourced the most recruits for Alabama fisheries); (2) proximity between juvenile and adult habitats (i.e. highest unit-area contribution from Alabama-Mississippi meadows); and (3) unidirectional, alongshore migration of egressing juveniles (i.e. primarily east-to-west movement, enhancing connectivity with Florida panhandle nurseries, and dampening connectivity with Chandeleur nurseries).

Spatial Patterns in Relative Abundance and Habitat Use of Adult Gray Snapper off the Southeastern Coast of the United States

AbstractGray Snapper Lutjanus griseus is an economically and ecologically important species in the estuarine and coastal environments of the southeastern United States. Previous research has focused primarily on juvenile Gray Snapper due to their accessible inshore distribution and ecological importance, while adults, which often occur offshore and are the main focus of fishing pressure, remain poorly understood. Seven years of baited underwater video data (2011–2017; N = 8,379 videos; ~14,000 h of video) were collected along the continental shelf between North Carolina and Florida (~100,000 km2) to better understand the ways in which the relative abundance of Gray Snapper varied by space, time, habitats, and environmental conditions. Adult Gray Snapper were observed on 6.9% of the videos overall, but they were much more commonly observed in Florida (16.9% of the videos) compared with the states that are north of Florida (1.4% of the videos). We used delta‐generalized additive models to determine that adult Gray Snapper primarily occurred in high‐relief hardbottom sites south of St. Augustine, Florida, in warm water less than 50 m deep, after accounting for imperfect detection on video. Temporal variability was relatively minor despite relatively high precision (the mean annual coefficient of variation = 24%). Fifteen large aggregations of Gray Snapper (i.e., &gt;20 individuals counted on a single frame) were observed on video, but it is unclear whether these aggregations indicated potential spawning aggregation sites. This work provides greater insight into the ecology of Gray Snapper during their important coastal‐ocean adult life stage, which will improve their management and conservation.

INFLUENCES OF UPPER FLORIDAN AQUIFER WATERS ON RADIOCARBON IN THE OTOLITHS OF GRAY SNAPPER (Lutjanus griseus) IN THE GULF OF MEXICO

ABSTRACTThe otoliths (ear stones) of fishes are commonly used to describe the age and growth of marine and freshwater fishes. These non-skeletal structures are fortuitous in their utility by being composed of mostly inorganic carbonate that is inert through the life of the fish. This conserved record functions like an environmental chronometer and bomb-produced radiocarbon (14C)—a 14C signal created by atmospheric testing of thermonuclear devices—can be used as a time-specific marker in validating fish age. However, complications from the hydrogeology of nearshore marine environments can complicate 14C levels, as was the case with gray snapper (Lutjanus griseus) along the Gulf of Mexico coast of Florida. Radiocarbon of these nearshore waters is influenced by freshwater input from the karst topography of the Upper Floridan Aquifer—estuarine waters that are 14C-depleted from surface and groundwater inputs. Some gray snapper likely recruited to this kind of environment where 14C levels were depleted in the earliest otolith growth, although age was validated for individuals that were not exposed to 14C-depleted waters to an age of at least 25 years with support for a 30-year lifespan.