Coast Of America Research Articles

Observation-based trajectory of future sea level for the coastal United States tracks near high-end model projections

With its increasing record length and subsequent reduction in influence of shorter-term variability on measured trends, satellite altimeter measurements of sea level provide an opportunity to assess near-term sea level rise. Here, we use gridded measurements of sea level created from the network of satellite altimeters in tandem with tide gauge observations to produce observation-based trajectories of sea level rise along the coastlines of the United States from now until 2050. These trajectories are produced by extrapolating the altimeter-measured rate and acceleration from 1993 to 2020, with two separate approaches used to account for the potential impact of internal variability on the future estimates and associated ranges. The trajectories are used to generate estimates of sea level rise in 2050 and subsequent comparisons are made to model-based projections. It is found that observation-based trajectories of sea level from satellite altimetry are near or above the higher-end model projections contained in recent assessment reports, although ranges are still wide.

Первые научные экспедиции в Берингов пролив и к российским колониям в Америке

Based on the geographical atlases of the 16th century, the German scientist G. Leibniz proposed to Peter I a project aimed at discovering a strait between Asia and America, studying the Earth’s magnetic field, cartographic and other research in Russia. In December 1724, Peter I signed a decree on equipping the expedition, which was called the First Kamchatka Expedition (1725–1730). In 1732, the expedition of I. Fedorov and M.S. Gvozdev through the Bering Strait approached the northwestern coast of America in the area of Cape Gvozdev (now — Cape Prince of Wales). At the same time, members of the Admiralty Board N.F. Golovin and T. Sanders proposed organizing Russian round-the-world voyages and creating a Pacific Fleet to protect Russia's Far Eastern borders. In 1741, the Second Kamchatka Expedition of V.I. Bering and A.I. Chirikov explored the northwestern coast of America and the islands of the Aleutian ridge. In 1763, M.V. Lomonosov justified the possibility of passing the Northern Sea Route through the Pole to Kamchatka. In 1764–1769, by the order of Catherine II, K. Krenitsyn and M.D. Levashov sent a secret expedition to the Bering Strait, which initiated a systematic mapping of the Aleutian Islands and Alaska. The expedition of I. Billings and G.A. Sarychev (1785–1796) resulted in the publication of maps of the Pacific Ocean. By the beginning of the 19th century, the question of the sea route to the Atlantic from the Bering Sea through the Arctic Ocean remained open. I.F. Kruzenshtern developed his own plan for organizing round-the-world voyages and received state support. Emperor Alexander I granted the request of the head of the Russian-American Company, N.P. Rezanov about sending goods to the Pacific colonies by sea and establishing interstate relations with Japan, which made it possible to equip the first Russian round-the-world expedition under the command of I.F. Kruzenshtern and Yu.F. Lisyanskiy (1803–1806).

The 30th anniversary of hurricane Andrew: Evolution of the Florida homeowners insurance market

AbstractHurricane Andrew made landfall in Homestead, Florida as a category 5 hurricane on August 24, 1992. This 30‐year anniversary review examines the changes within the Florida and coastal United States homeowners insurance markets. We review market changes specifically related to market concentration, risk pricing, and volatility. We find that most states have become less concentrated since the early 1990s. We also find that risk pricing has changed since Hurricane Andrew with the creation of a new catastrophe market where insurers rely on catastrophe models to help price catastrophe‐prone risks. Finally, we see that most states did not experience much volatility over the 30 years following Hurricane Andrew, with Florida being an exception. This is most likely due to the large population growth, increase in fraudulent claims, and high litigation costs. Overall, Hurricane Andrew changed how the insurance industry viewed catastrophic events and thus changed how they manage, model, and price catastrophe‐prone areas.

A new, narrowly endemic species of swamp-dwelling dusky salamander (Plethodontidae: Desmognathus) from the Gulf Coastal Plain of Mississippi and Alabama.

We describe a new, narrowly endemic species of swamp-dwelling dusky salamander (Plethodontidae: Desmognathus pascagoula sp. nov.) from the Gulf Coastal Plain of southeastern Mississippi and southwestern Alabama based on linear morphometrics, mitochondrial DNA, and single nucleotide polymorphisms from 881 loci produced using genotype-by-sequencing. Some populations of the new species were historically referred to as D. auriculatus, a polyphyletic assemblage of at least three species in the Atlantic and Gulf Coastal Plain from Texas to North Carolina. Populations of D. auriculatus from the Gulf Coastal Plain in Louisiana and Mississippi were recently described as D. valentinei. The new species includes populations that were tentatively referred to D. valentinei, but we find it is morphologically, genetically, and geographically distinct. It is smaller, has a more defined dorsal color pattern, more irregular whitish portholes in up to three rows on the lateral surfaces of the body and tail, and a brighter orange or yellowish orange postocular stripe. At present, the new species is known from only six extant populations in the lower Pascagoula, Escatawpa, and Mobile drainages. The latter represents a distinct phylogeographic lineage. We also refer a historical collection from the northeastern side of the Mobile-Tensaw River Delta to this species, suggesting a much broader range in the past. We suspect that more populations remain to be discovered in the area, and their potential species-level distinctiveness should be tested further. This discovery increases knowledge of the biodiversity in the southeastern United States Coastal Plain, a candidate region meeting the global criteria for a biodiversity hotspot, and underscores the amount of cryptic diversity likely remaining to be discovered and described in Nearctic salamanders.

Comparing surface wind stress and sea surface temperature biases over the tropical and subtropical oceans in subsets of CMIP6 models categorized by frozen hydrometeors-radiation interactions

We evaluate the simulations of surface wind stress (TAU) and sea surface temperature (SST) over subtropical and tropical Pacific and Atlantic oceans in subsets of CMIP6 models that are categorized by frozen hydrometeors-radiation interactions. The CMIP6 models are divided into two subsets with combined (SON1) and separated (SON2) radiative properties of cloud ice and falling ice (snow) and compared to the set with cloud ice radiative effects only (NOS). There is evidence that these hydrometeors-radiation interaction treatments induce different atmospheric dynamic responses that influence the surface properties. Excessive westerly TAU and meridional TAU divergence away from convective zones are reduced significantly in SON1 and SON2 relative to NOS against QuikSCAT observations; while the differences between SON2 and SON1 are small. SON2 reduces cold SST biases over north oceans and equatorial zones drastically (1 to 2 K), and warm biases (up to 1 K) off the coasts of America and zonal TAU biases are reduced relative to NOS. Unlike SON2, SON1 improves SSTs mainly over south of Pacific Ocean and limited areas over the tropical belts relative to NOS although TAU is reduced drastically as in SON2, implying that other factors play a role in degrading the SST simulations in SON1 relative to SON2. SON2 outperforms NOS and SON1 in the seasonal cycles of SST mean biases and mean absolute biases averaged over the equatorial area, north ocean, and South Pacific against ERSST observations. Despite the significant improvements in TAU and SST simulations, SON2 models still exhibit non-trivial biases over south and north flanks of equatorial zones. These results suggest that there are direct linkages of TAU with SST changes resulting from the hydrometeors-radiation interactions in SON2, but not in SON1, relative to NOS, implying that a separated treatment of cloud ice and falling ice radiative properties in climate models is preferred.

Allometry of Mexican hogfish (Bodianus diplotaenia) for predicting the body length of individuals from two pre‐Columbian sites in the Pearl Island archipelago (Panama)

AbstractThe Mexican hogfish (Osteichthyes: Labridae, Bodianus diplotaenia Gill, 1862) is widely distributed throughout the tropical eastern Pacific from the Gulf of California to northern Peru, including all oceanic islands. Artisanal fishers occasionally capture it today and its remains are recovered at pre‐Columbian dwelling sites along the Pacific Coast of America. This paper addresses the advantages of using allometry to estimate size ranges of Mexican hogfish in pre‐Hispanic archeological samples from two ancient settlements in the Pearl Island archipelago of Panama: (1) Playa Don Bernardo (PdB), a preceramic site (6.2–5.6 kya), and (2) Bayoneta Island (BY‐10), a ceramic site (~1 kya). For creating the allometric model, a modern collection composed of 39 individuals covering a wide range of sizes and weights was used. All individuals have complete information about their total length (TL) and standard length (SL), which were recorded in millimeters (mm), and their total fresh weight (W) in grams (g). The TL of the sample ranged between 265 and 750 mm, and the SL between 210 and 487 mm. The W ranged between 273 and 3450 g. The most frequent bones (11) and otoliths were selected and 29 measurements were taken. The total length–weight relationship was W = 2E−05 TL3.0857 with R2 = 0.984. In general, it was observed that the relationships between the TL and the bone measurements had a strong correlation (R2 > 0.95). At PdB, the mean reconstructed length was 289.6 mm (TL), and at BY‐10, it was 283.6 mm (TL). The study of the archeological samples of B. diplotaenia could be used as a point of reference in modern ecological studies and fisheries management particularly in the Pearl Island archipelago.

Influence of landscape and vegetation characteristics on herpetofaunal assemblages in Gulf Coastal Plain pine forests

AbstractLongleaf pine (Pinus palustris) savanna characterized by open‐canopy, diverse herbaceous vegetation, and high amounts of bare soil once covered much of the southeastern United States Coastal Plain. The unique structural and vegetative conditions of this ecosystem support endemic reptiles and amphibians that have declined as longleaf pine forests have been lost or degraded. Private working pine (Pinusspp.) forests managed for timber production now occur throughout the southeastern United States and have replaced much of the historical longleaf pine savanna. The examination of herpetofaunal (reptile, amphibian) communities in private working loblolly pine (P. taeda) landscapes, particularly in the western Gulf Coastal Plain is lacking. Using repeated field surveys and hierarchical community occupancy models, we examined occupancy and species richness of herpetofauna across 81 sites spanning gradients of management practices, vegetative conditions, and soil composition in northwestern Louisiana, USA, 2017–2019. Young pine stands (<6 yr) exhibited structural characteristics most similar to mature longleaf pine reference sites (>30 yr), while mid‐aged stands (13–26 yr) often featured closed canopy and dense midstory. Vegetation conditions varied widely depending on landscape characteristics and site‐specific disturbance regimes. We documented 43 species of herpetofauna, including 9 open‐pine‐associated species. Occupancy of open‐pine‐associated herpetofauna was positively associated with open‐canopy and understory conditions, and sandy soil area. Sites providing open‐canopy conditions were often occupied by open‐pine‐associated species regardless of overstory type and disturbance method. Overall richness of herpetofauna was greatest at sites with moderate canopy cover outside of sandy soil regions. Working pine landscapes in the western Gulf Coastal Plain can support diverse herpetofaunal assemblages, including open‐pine‐associated species, when management practices maintain open‐canopy conditions on sandy, upland soils. More broadly, our results provide insight into how forest management practices affect herpetofauna and may guide practices that can contribute to conservation value of working pine forests.

News coverage of ocean issues and its impacts on public perceptions and conservation information‐seeking of sea turtles

AbstractThe news media can influence how the public learns about environmental issues, including endangered marine species such as sea turtles, which may prompt further information‐seeking. However, what people learn through the media can be problematic for conservation efforts if it is misaligned with scientific priorities. Here, we seek to better understand how members of the public learn about sea turtles through the news, assess public perceptions and knowledge about these animals, and evaluate how these variables are associated with information‐seeking behavior on their conservation. We surveyed a representative sample of 1162 adults living in the coastal United States and collected information on ocean news consumption, sea turtle interest, risk perceptions of sea turtle population status and individual threat types, self‐reported knowledge, and information‐seeking behavior. News consumption was associated with interest, risk perceptions of population status, and self‐reported knowledge about sea turtles. Although news consumption was not associated with risk perception about individual hazards, individuals generally viewed pollution as a top hazard facing sea turtle populations, which may misalign with scientific understanding. Greater interest, risk perceptions of population status and overall threat, and knowledge was associated with more information‐seeking behavior, with knowledge moderating the relationship between risk perceptions of population status and information‐seeking behavior. These findings improve understanding of how the public learns about sea turtles through the news media, suggests coupling messaging about sea turtles with their risks may provide more effective conservation messaging, and highlights how educators and conservation stakeholders can use the news as a communication tool.

Healthcare experiences of uninsured and under-insured American Indian women in the United States

BackgroundExtensive health disparities exist for American Indian groups throughout the United States. Although insurance status is linked to important healthcare outcomes, this topic has infrequently been explored for American Indian tribes. For state-recognized tribes, who do not receive healthcare services through the Indian Health Service, this topic has yet to be explored. The purpose of this study is to explore how having limited access to health insurance (being uninsured or under-insured) impact American Indian women's healthcare experiences?.MethodsIn partnership with a community advisory board, this study used a qualitative description approach to conduct thirty-one semi-structured life-course interviews with American Indian women who are members of a state-recognized tribe in the Gulf Coast (United States) to explore their Western healthcare experiences. Interview were conducted at community centers, participant homes, and other locations identified by participants. Interviews were transcribed verbatim and findings were analyzed in NVivo using conventional content analysis. Findings were presented at tribal council meetings and to participants for member checking.ResultsThemes identified by participants included: (a) lack of insurance as a barrier to healthcare; (b) pre-paying for childbirth when uninsured; and (c) access to public health insurance coverage. Twenty-four women mentioned the role or importance of insurance in discussing their healthcare experiences, which was referenced a total of 59 times.ConclusionThese findings begin to fill an important gap in the literature about the health insurance experiences of American Indian tribal members. Not having insurance was an important concern for participants, particularly for elderly and pregnant tribal members. Not having insurance also kept tribal members from seeking healthcare services, and from getting needed prescriptions. In addition to promoting knowledge about, and expanding insurance options and enrollment, increased sovereignty and resources for state-recognized tribes is needed to address the health disparities experienced by American Indian groups.

Assessing population exposure to coastal flooding due to sea level rise

The exposure of populations to sea-level rise (SLR) is a leading indicator assessing the impact of future climate change on coastal regions. SLR exposes coastal populations to a spectrum of impacts with broad spatial and temporal heterogeneity, but exposure assessments often narrowly define the spatial zone of flooding. Here we show how choice of zone results in differential exposure estimates across space and time. Further, we apply a spatio-temporal flood-modeling approach that integrates across these spatial zones to assess the annual probability of population exposure. We apply our model to the coastal United States to demonstrate a more robust assessment of population exposure to flooding from SLR in any given year. Our results suggest that more explicit decisions regarding spatial zone (and associated temporal implication) will improve adaptation planning and policies by indicating the relative chance and magnitude of coastal populations to be affected by future SLR.

Discharge and Temperature Controls of Dissolved Organic Matter (DOM) in a Forested Coastal Plain Stream

Streams in the southeastern United States Coastal Plains serve as an essential source of energy and nutrients for important estuarine ecosystems, and dissolved organic matter (DOM) exported from these streams can have profound impacts on the biogeochemical and ecological functions of fluvial networks. Here, we examined hydrological and temperature controls of DOM during low-flow periods from a forested stream located within the Coastal Plain physiographic region of Alabama, USA. We analyzed DOM via combining dissolved organic carbon (DOC) analysis, fluorescence excitation–emission matrix combined with parallel factor analysis (EEM-PARAFAC), and microbial degradation experiments. Four fluorescence components were identified: terrestrial humic-like DOM, microbial humic-like DOM, tyrosine-like DOM, and tryptophan-like DOM. Humic-like DOM accounted for ~70% of total fluorescence, and biodegradation experiments showed that it was less bioreactive than protein-like DOM that accounted for ~30% of total fluorescence. This observation indicates fluorescent DOM (FDOM) was controlled primarily by soil inputs and not substantially influenced by instream production and processing, suggesting that the bulk of FDOM in these streams is transported to downstream environments with limited in situ modification. Linear regression and redundancy analysis models identified that the seasonal variations in DOM were dictated primarily by hydrology and temperature. Overall, high discharge and shallow flow paths led to the enrichment of less-degraded DOM with higher percentages of microbial humic-like and tyrosine-like compounds, whereas high temperatures favored the accumulation of high-aromaticity, high-molecular-weight, terrestrial, humic-like compounds in stream water. The flux of DOC and four fluorescence components was driven primarily by water discharge. Thus, the instantaneous exports of both refractory humic-like DOM and reactive protein-like DOM were higher in wetter seasons (winter and spring). As high temperatures and severe precipitation are projected to become more prominent in the southeastern U.S. due to climate change, our findings have important implications for future changes in the amount, source, and composition of DOM in Coastal Plain streams and the associated impacts on downstream carbon and nutrient supplies and water quality.

Changes of South‐Central Pacific Large‐Scale Environment Associated With Hydrometeors‐Radiation‐Circulation Interactions in a Coupled GCM

AbstractA common deficiency in coupled atmosphere‐ocean models is the lack of stratocumulus clouds near the west coasts of continents and shallow cumulus clouds over the trade wind regions. In this study, we examine changes of large‐scale trade wind environment associated with hydrometeors‐radiation‐circulation interactions, focusing over the south‐central Pacific, by carrying out experiments with falling ice (snow) radiative effects (FIREs) on or off using the CESM1‐CAM5 coupled model. Compared to observations/reanalysis data and an experiment with FIREs on (SON), an experiment with FIREs off (NOS) tends to have too‐high (0.3–0.9 K) sea surface temperature (SST) over the eastern half of the Pacific, and weaker surface wind stress over the northeast side but stronger stress over the southwest side of the study domain. The difference between NOS and SON shows lower‐tropospheric wind fields with a cyclonic‐like wind pattern, which is similar to surface wind stress, accompanied with weaker subsidence over the northeast side. The cyclonic‐like wind pattern causes stronger moisture convergence, accompanied with horizontal warm and moist advections, and stronger effective ascending motion over the northeast side of the study domain, building large‐scale environmental conditions to facilitate middle‐ and high‐clouds instead of shallow cumulus clouds in nature. This large‐scale environment in conjunction with the higher SSTs may be also responsible for the lack of the stratocumulus clouds near the coast of America. Remaining biases in SON such as the double intertropical convergence zone and parameterization deficiencies may also prevent a more realistic simulation of trade wind clouds and their associated large‐scale environments.

Beneficial Use Decision Support for Wetlands: Case Study for Mobile Bay, Alabama

The beneficial use of dredged material (BUDM) for wetland restoration improves coastal wetland resilience and conserves coastal natural infrastructure. Tools, such as biophysical models help coastal managers to assess habitat vulnerability and plan restoration. In this study, the Marsh Equilibrium Model (MEM) will be utilized combined with observed data to predict future conditions and evaluate potential marsh restoration via the BUDM in Mobile Bay, Alabama. A range of site conditions and restoration strategies will be considered and the impacts on dredged material management area (DMMA) volumes will be evaluated. Wetland restoration via thin-layer placement (TLP) of dredged material (DM) restores marsh elevation to combat sea level rise (SLR) and conserves fill capacity in DMMAs. A simplified mapping approach to assess this type of restoration will be demonstrated using wetland area and DM sources to determine the coastal United States wetland area to which it could be further applied. The mapping exercise revealed that 6,240 km2 of US wetlands were suitable for restoration and sediment resources exist to conduct this type of restoration from navigational dredging. The further development of a spatial application of the MEM is needed to provide an operational tool for managers and refine these restoration estimates.

Invasive Wild Pigs: A Significant Disturbance in Coastal Forests

Introduced in ~59 countries and native across Europe and Asia, wild pigs, Sus scrofa, are the most wide-spread swine species in the world. As ecosystem engineers, wild pigs are a significant source of disturbance in introduced ecosystems due to their numerous, complex impacts on ecosystem processes. Wild pigs are often found in the resource-rich habitat of coastal forests. Coastal forests are complex, dynamic systems with tremendous biodiversity. Exposed to recurrent disturbances, the biophysical characteristics of coastal forests contribute to their ability to return to their original state post-disturbance. However, compounding disturbances can weaken this ability and threaten the health and function of the ecosystem. In this review, through the model of the forests of the southeastern United States Coastal Plain, we (1) describe conditions found across the forested coastal landscape, (2) describe wild pig disturbance, and (3) discuss how wild pig impacts can add to significant anthropogenic and climate-related disturbances threatening coastal forests. Through this review, we find that the impacts of wild pig disturbance on coastal forests often have similar effects as anthropogenic and climate change-related disturbances that may enhance these significant threats to coastal forest function and resiliency.

Regime Behavior in the Upper Stratosphere as a Precursor of Stratosphere-Troposphere Coupling in the Northern Winter

AbstractA new regime index is constructed to capture the seasonal development of the stratospheric polar vortex in the northern winter, based on the standard deviation of Ertel’s potential vorticity in the upper stratosphere in November-December. The narrow-jet flow regime is characterized by a polar vortex that is more confined to high latitudes in the early winter upper stratosphere. This upper-level vortex configuration is more susceptible to the disturbances of upward propagating planetary-scale Rossby waves; the stratospheric polar vortex thus weakens earlier and is vertically shallower. The wide-jet flow regime is characterized by a broader-than-average polar vortex that extends further into the subtropics in the early-winter upper stratosphere. The polar night jet then gradually strengthens, moves poleward and penetrates deep into the lowermost stratosphere, with a sharply-defined polar vortex edge accompanied due to more frequent Rossby wave breaking.Composite differences analyses show that the wide and narrow jet regimes, defined in the uppermost stratosphere in November-December, lead to different circulation anomalies of the lower-stratosphere and the troposphere in January-February, offering the potential for improved predictability of sub-seasonal to seasonal forecasts up to two months ahead. The lower tropospheric responses in January-February are zonally asymmetric. The narrow-jet regime projects most strongly over the North Atlantic, with an equatorward-shifted, and/or broader mid-latitude westerly jet. The wide-jet-regime response is characterized by a weakened mid-latitude westerly jet over the North Pacific. The two flow regimes also differ in their impacts on the storm track over Western Europe and the east coast of America, which may have implications for extreme weather events in those regions.

Characterization of simulated extreme El Niño events and projected impacts on South American climate extremes by a set of Coupled Model Intercomparison Project Phase 5 global climate models

AbstractIn this study the simulated extreme and moderate El Niño events (e.g., frequency of occurrence and spatial variability) are characterized and the historical teleconnections on precipitation and temperature climate extremes in South America are analysed. Future projected changes in these teleconnections under a global warming context are also addressed. For this purpose a set of 10 Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models (GCMs) simulations derived from three experiments (historical, RCP4.5 and RCP8.5) are considered. The study period is 1916–2100. As El Niño is seasonally phase‐locked, peaking in late austral spring and summer, the present analysis is carried out for these two seasons, as well as annually. Results indicate that extreme El Niño events are projected to double their occurrence considering RCP4.5 and RCP8.5, while a less pronounced increase is projected for moderate El Niño events. Most of these events show a similar pattern of sea surface temperature (SST) anomalies: a positive centre in the central equatorial Pacific that extends eastward to the coast of America. In a global warming context, the resemblance between these events may decrease. Overall, the spatial structure of the impacts of El Niño are expected to be similar between moderate and extreme events, although in some cases (regions and seasons), a higher intensity is observed considering the events characterized as extreme El Niños rather than moderate ones. As extreme El Niño events are expected to be more frequent in the future, the impacts on climate extremes as well as the associated socioeconomic impacts would also take place much more frequently too.

Molecular diversity within the genus Laeonereis (Annelida, Nereididae) along the west Atlantic coast: paving the way for integrative taxonomy.

The polychaete genus Laeonereis (Annelida, Nereididae) occurs over a broad geographic range and extends nearly across the entire Atlantic coast of America, from the USA to Uruguay. Despite the research efforts to clarify its diversity and systematics, mostly by morphological and ecological evidence, there is still uncertainty, mainly concerning the species Laeonereis culveri, which constitutes an old and notorious case of taxonomic ambiguity. Here, we revised the molecular diversity and distribution of Laeonereis species based on a multi-locus approach, including DNA sequence analyses of partial segments of the cytochrome c oxidase subunit I (COI), 16S rRNA, and 28S rRNA genes. We examined Laeonereis specimens collected from 26 sites along the American Atlantic coast from Massachusetts (USA) to Mar del Plata (Argentina). Although no comprehensive morphological examination was performed between different populations, the COI barcodes revealed seven highly divergent MOTUs, with a mean K2P genetic distance of 16.9% (from 6.8% to 21.9%), which was confirmed through four clustering algorithms. All MOTUs were geographically segregated, except for MOTUs 6 and 7 from southeastern Brazil, which presented partially overlapping ranges between Rio de Janeiro and São Paulo coast. Sequence data obtained from 16S rRNA and 28S rRNA markers supported the same MOTU delimitation and geographic segregation as those of COI, providing further evidence for the existence of seven deeply divergent lineages within the genus. The extent of genetic divergence between MOTUs observed in our study fits comfortably within the range reported for species of polychaetes, including Nereididae, thus providing a strong indication that they might constitute separate species. These results may therefore pave the way for integrative taxonomic studies, aiming to clarify the taxonomic status of the Laeonereis MOTUs herein reported.

Size Changes within a Southeastern United States Coastal Shark Assemblage: 1975–2018

AbstractHarvest may have myriad effects on target species, including a change in population size structure. To assess whether size shifts have occurred among managed coastal species of shark (superorder Selachimorpha), we examined the population size structure of 12 species caught during a nearly five‐decade‐long fishery‐independent survey conducted in Onslow Bay, North Carolina, using standardized longline gear. We evaluated trends in mean fork length (FL), median FL, and index of maximum FL (L90%) for each species separately across time using linear regression models. We also examined trends in size‐classes (200‐mm bins) and catch per unit effort for each species over time. For 10 of the 12 species (excluding sample‐size‐constrained Tiger Shark Galeocerdo cuvier and Bull Shark Carcharhinus leucas), size structure metrics indicated decreasing sizes over time, although statistical confidence for these patterns varied across species and metrics. Strongest statistical support for declining sizes was observed for Blacknose Shark Carcharhinus acronotus (mean FL, median FL, L90%), Dusky Shark Carcharhinus obscurus (L90%), Smooth Dogfish Mustelus canis (L90%), and Atlantic Sharpnose Shark Rhizoprionodon terraenovae (L90%). Magnitude of decreases in L90% among these 10 species during the survey ranged from roughly 9% (Silky Shark Carcharhinus falciformis; 83‐mm decrease) to 35% (Sandbar Shark Carcharhinus plumbeus; 541‐mm decrease). Our findings indicate a potential for fishing pressure to exert directional selection on these coastal shark species, although further research is needed regarding the nature of size‐dependent catchability and species‐specific vital rates to adequately evaluate these dynamics. Furthermore, in addition to the removal of “great sharks,” decreasing sizes of small coastal sharks, such as Blacknose Shark, Smooth Dogfish, and Atlantic Sharpnose Shark (i.e., “mesopredators”), suggest that harvest may have pervasive effects on species throughout this assemblage.

Taxonomy of Centropomus Lacépède, 1802 (Perciformes: Centropomidae), with focus on the Atlantic species of the genus.

Centropomus Lacépède, 1802 comprises 13 species of the fishes popularly knows as snooks, distributed in both Atlantic and Pacific coasts of America. Despite several studies on the group, conflicting taxonomic classifications still exist, including overlapping diagnostic characters, rendering species diagnoses extremely difficult. Herein, we review the taxonomy of Centropomus to elucidate species identities, redefine their diagnoses and to assess interspecific relationships based on the examination of 376 specimens. The study included complementary approaches, as analyses of external morphologic characters, linear and geometric morphometrics, and molecular analyses. Forty-nine characters were used for external morphology, 17 discrete plus 32 linear measurements. Shape and size were analyzed through geometric morphometrics of 185 specimens in lateral view. Partial sequences of the gene cytochrome c oxidase I were obtained for 129 specimens representing 11 species. Based on the consistent results retrieved from the morphologic and molecular analyses, we recognized six species of Centropomus from the Atlantic coast (C. ensiferus, C. irae, C. parallelus, C. pectinatus, C. poeyi and C. undecimalis). Centropomus mexicanus is treated as a junior synonym of C. parallelus. Six species from the Pacific coast are also tentatively recognized (C. armatus, C. medius, C. nigrescens, C. robalito, C. unionensis, and C. viridis), however further studies on the Pacific species are still needed. Information on type material, diagnosis, distribution, and taxonomic comments are provided for each species. An identification key to the species of Centropomus is presented.

Size Changes within a Southeastern United States Coastal Shark Assemblage: 1975–2018

Size Changes within a Southeastern United States Coastal Shark Assemblage: 1975–2018