Gulf Populations Research Articles

Identification of novel microsatellite markers for P. argenteus from Kuwait waters

Silver pomfret is a coastal fish of economic significance. While its natural populations have dwindled due to various human activities, the genetic information on this species is still limited. We have used the next generation sequencing to identify microsatellites and developed corresponding primers in Arabian Gulf populations. PCR studies were performed on the 48 short-listed loci across multiple individuals from Iranian and Kuwait waters. Twenty-seven polymorphic loci were analyzed and 16 of them showed significant deviations from expected Hardy–Weinberg equilibrium, for the Iranian or Kuwait populations. The developed primers may be highly useful for detailed population genetic studies of silver pomfret from various geographical locations.

Nutrient allocation in the gonads of the sea urchin Arbacia dufresnii in different stages of gonadal development

This study reports nutrient allocation in different stages of gonadal development for two populations of the sea urchin Arbacia dufresnii off the Patagonian coast of Argentina (Nuevo Gulf and San Jorge Gulf). The biochemical composition of gonads was used to assess nutrient allocation by measuring ash, soluble protein, lipid and trichloroacetic acid-soluble carbohydrate concentrations, and absolute contents over a 24-month period. Reproductive output in terms of energy was calculated for females. Results were correlated with histological stage of the gonads. Soluble proteins were the main component for the Nuevo Gulf population while unmeasured organic material (i.e. insoluble proteins and nucleic acids, especially in testes) was prevalent in gonads from San Jorge Gulf. Soluble protein and lipid concentrations followed the gonadal cycle, while carbohydrate concentration was almost negligible, especially in the Nuevo Gulf population. The different patterns in the gonadal cycle in the two populations were reflected in the biochemical composition of gonads. Concentrations and contents of the biochemical components and reproductive output were higher in the population from San Jorge Gulf owing to the larger size of gonads and gametes. These findings contribute to the better understanding of the plasticity of the reproductive biology of A. dufresnii in different environments.

Deepwater Horizon crude oil impacts the developing hearts of large predatory pelagic fish

The Deepwater Horizon disaster released more than 636 million L of crude oil into the northern Gulf of Mexico. The spill oiled upper surface water spawning habitats for many commercially and ecologically important pelagic fish species. Consequently, the developing spawn (embryos and larvae) of tunas, swordfish, and other large predators were potentially exposed to crude oil-derived polycyclic aromatic hydrocarbons (PAHs). Fish embryos are generally very sensitive to PAH-induced cardiotoxicity, and adverse changes in heart physiology and morphology can cause both acute and delayed mortality. Cardiac function is particularly important for fast-swimming pelagic predators with high aerobic demand. Offspring for these species develop rapidly at relatively high temperatures, and their vulnerability to crude oil toxicity is unknown. We assessed the impacts of field-collected Deepwater Horizon (MC252) oil samples on embryos of three pelagic fish: bluefin tuna, yellowfin tuna, and an amberjack. We show that environmentally realistic exposures (1-15 µg/L total PAH) cause specific dose-dependent defects in cardiac function in all three species, with circulatory disruption culminating in pericardial edema and other secondary malformations. Each species displayed an irregular atrial arrhythmia following oil exposure, indicating a highly conserved response to oil toxicity. A considerable portion of Gulf water samples collected during the spill had PAH concentrations exceeding toxicity thresholds observed here, indicating the potential for losses of pelagic fish larvae. Vulnerability assessments in other ocean habitats, including the Arctic, should focus on the developing heart of resident fish species as an exceptionally sensitive and consistent indicator of crude oil impacts.

Biomagnification of mercury through a subtropical coastal food web off Southwest Florida

Total mercury and stable isotopes of nitrogen (δ(15) N) were measured in samples from 57 species of invertebrates (17 species) and finfish (40 species) from the coastal waters off southwest Florida, USA, to evaluate the biomagnification of mercury through the food web. Mercury concentrations (wet wt) and δ(15) N values were highly variable among species, ranging from 0.004 mg/kg in an unidentified species of brittlestar (class Ophiuroidea) to 2.839 ± 1.39 mg/kg in king mackerel (Scomberomorus cavalla) and from 4.67‰ in a Florida fighting conch (Strombus alatus) to 13.68‰ in crevalle jack (Caranx hippos). In general, observed Hg levels were in the upper range of levels previously reported for other Gulf populations. Species means of log-transformed Hg concentrations were positively correlated with δ(15) N (p < 0.001, r(2) = 0.66) and had a slope of 0.21. A trophic magnification factor of 5.05 was calculated from the relationship between log-transformed mean Hg concentrations and trophic level (calculated from δ(15) N), indicating that Hg increased by a factor of 5 with each increase in trophic level. The log10 [Hg]-δ(15) N slope and trophic magnification factor were also in the upper range of values reported from other regions and ecosystems.

Demography and Population Dynamics of Massive Coral Communities in Adjacent High Latitude Regions (United Arab Emirates)

Individual massive coral colonies, primarily faviids and poritids, from three distinct assemblages within the southeastern Arabian Gulf and northwestern Gulf of Oman (United Arab Emirates) were studied from 2006–2009. Annual photographic censuses of approximately 2000 colonies were used to describe the demographics (size class frequencies, abundance, area cover) and population dynamics under “normal” environmental conditions. Size class transitions included growth, which occurred in 10–20% of the colonies, followed in decending order by partial mortality (3–16%), colony fission (<5%) and ramet fusion (<3%). Recruitment and whole colony mortality rates were low (<0.7 colonies/m2) with minimal interannual variation. Transition matrices indicated that the Arabian Gulf assemblages have declining growth rates (λ<1) whereas the massive coral population is stable (λ = 1) in the Gulf of Oman. Projection models indicated that (i) the Arabian Gulf population and area cover declines would be exacerbated under 10-year and 16-year disturbance scenarios as the vital rates do not allow for recovery to pre-disturbance levels during these timeframes, and (ii) the Gulf of Oman assemblage could return to its pre-disturbance area cover but its overall population size would not fully recover under the same scenarios.

Icriocarcinidae: a family of portunoid crabs from the Upper Cretaceous of North America

Icriocarcininae Stevcic, 2005, an extinct North American subfamily of portunoid decapods, is elevated to family level to contain two Late Cretaceous genera—Icriocarcinus Bishop, 1988, from the Pacific Coast, and Branchiocarcinus Feldmann and Vega, 1995, from the Gulf of Mexico and Atlantic Coast Plain. The family is centered on Icriocarcinus xestos Bishop, 1988, described from the Late Campanian of Baja California. Closely allied with this species are: “Eryma” flecta Rathbun, 1926, originally described from the latest Campanian of Tennessee and now known to occur throughout the Maastrichtian of the adjoining Mississippi; Branchiocarcinus cornatus Feldmann and Vega, 1995, from the Maastrichtian of San Luis Potosi, Mexico; and undescribed material from the latest Maastrichtian of New Jersey. The Gulf and Atlantic populations compose a single new species—Branchiocarcinus flectus (Rathbun). Provisionally regarded as a lobster, on the basis of a single, eroded chela, B. flectus is now known from complete bodies found at several locations in the eastern US. The additional material also clarifies the identity of B. cornatus, which is based on a distorted external mold of a lone dorsal carapace. Members of the family lack the typical portunoid flattened fifth pereiopod but share other characters that enable placement within the Portunoidea.

Comparative growth and mortality of cultured Lion's Paw scallops (Nodipecten subnodosus) from Gulf of California and Pacific populations and their reciprocal transplants

This study focused on the comparison of growth and mortality of Lion's Paw scallops Nodipecten subnodosus from Gulf of California and Pacific populations and their reciprocal transplants, cultured in suspended module and bottom culture in Baja California Sur, Mexico. Environmental parameters were monitored to determine site-specific differences and were correlated with scallops' population-specific responses. Significant differences in growth were found between sites, populations and grow-out methods. Growth performance of scallops originating from the Pacific population was lower and uniform between Pacific and Gulf culture sites, whereas Gulf scallops cultured at the Pacific site grew better. Growth and survival was higher in suspended than bottom culture, mainly due to depth-associated differences in food and oxygen supply. Increasing temperatures and decreasing food and oxygen during summer months resulted in depressed growth and elevated mortality. At the Pacific site, this was partially compensated by considerably higher food availability. Gulf scallops resisted high diurnal temperature changes at San Buto significantly better than Pacific scallops. They also survived generally better than the Pacific population, independent of site and grow-out method, indicating physiological adaptations to high temperatures and low food availability in their habitat. Consequently, the Gulf population appears to be more feasible for aquaculture operations in coastal lagoons with stressful conditions.

The A1chieve study - an observational non-interventional study of patients with type 2 diabetes mellitus initiating or switched to insulin analogue therapy: subgroup analysis of the Gulf population

To evaluate the safety and effectiveness of insulin analogues (insulin aspart, insulin detemir and biphasic insulin aspart 30, alone or in combination) in type 2 diabetes mellitus (T2DM) patients in routine clinical practice in the Gulf as a subgroup of the A(1) chieve multi-national study. A total of 10,704 T2DM Gulf patients with uncontrolled T2DM on oral antidiabetics ± insulins other than insulin aspart, insulin detemir or biphasic insulin aspart 30, who initiated or switched to study insulins were included and followed up for 24 weeks in the context of the A(1) chieve study. Baseline HbA(1c) (± SD) was poor: 9.7 ± 1.7%. At Week 24, an improvement in HbA(1c) of -2.3 ± 1.6% was observed in the entire cohort, and -2.4 ± 1.5% and -2.1 ± 1.7% for insulin-naïve patients and prior insulin users respectively. Overall, rates of hypoglycaemia increased in those new to insulin therapy, whereas a reduction was observed in those switching from other insulins. A marginal reduction in body weight (-0.8 ± 4.4 kg) was noted in the entire cohort, whereas the overall lipid profile and systolic blood pressure (-6.2 ± 15.3 mmHg) improved. Initiating or switching to insulin analogues was well tolerated and resulted in significant improvements in glycaemic control in T2DM patients in the Gulf.

Tagging studies reveal restricted movement of snapper (Pagrus auratus) within Shark Bay, supporting fine-scale fisheries management

The snapper (Pagrus auratus) fisheries of Shark Bay’s complex inner gulfs are managed on a fine spatial scale (tens of kilometres). Following the splitting of the Western Gulf into two management zones, results from an earlier 1980s tagging study were revisited to assess the suitability of management arrangements. Recaptures up to 15 years at liberty showed highly restricted movement, with 300 of 491 occurring within 5 nautical miles of the tagging site and only 3.3% crossing the new zone boundary. A simple stock-trajectory model simulating the two Western Gulf populations demonstrated a negligible impact from a 1% per annum level of mixing. The 1980s study was repeated between 1998 and 2003 by tagging 2558 snapper, mainly in areas previously under-represented. Recaptures up to 2 years at liberty again showed highly restricted movement, with 181 of 197 recaptures occurring at the tagging site. Juveniles were more sedentary than adults, the latter showing limited evidence of inter-annual spawning-site fidelity. Together, both studies support the use of three small management zones. Community acceptance of these complex arrangements was aided by collaborating with volunteers on research programs, which improved their understanding of the population structure.

Variación de color de la serpiente marina Pelamis platura (Serpentes: Elapidae) en el Golfo Dulce, Puntarenas, Costa Rica

La serpiente marina de vientre amarillo (Pelamis platura) tiene el mayor ámbito de distribución entre todas las serpientes marinas, y a lo largo de su rango la especie exhibe gran variación en su patrón y color. El color de la mayoría de los ejemplares es negro con café y/o amarillo, que se muestran dentro un patrón variable, aunque ejemplares sin patrón de color amarillo brillante se han reportado de ciertas localidades de Costa Rica y Panamá. Recientemente en el interior de la cuenca del Golfo Dulce, al sur de la costa Pacífica de Costa Rica, se descubrió una población donde todos los ejemplares muestran cantidades extensivas de color amarillo. La evidencia sugiere que los patrones de circulación de las corrientes superficiales en el interior y exterior de este golfo de tipo fiordo, aparentemente son suficientes para interrumpir el flujo o intercambio genético entre la población oceánica y la del Golfo Dulce. La falta o pérdida de la pigmentación oscura en el dorso de la población del Golfo Dulce puede haber sido el resultado de las temperaturas del agua y otras condiciones particulares en esta cuenca anóxica, única en la costa Pacífica del Hemisferio Occidental.

Elasmobranchs of the Persian (Arabian) Gulf: ecology, human aspects and research priorities for their improved management

Given widespread concern about the status of elasmobranch fishes globally, information on this group in the Persian (Arabian) Gulf is reviewed comprehensively for the first time. The Arabian region may be of overlooked significance to elasmobranch biogeography, and the environmentally unique Gulf has some highly distinctive elements of biodiversity: an endemic and critically endangered rajid skate, a rarely recorded carcharhinid shark, and preliminary molecular studies which indicate intriguing levels of distinctness from conspecifics elsewhere in the Indo-Pacific. Elasmobranchs also have a long history of association with, and exploitation by, humans around the Gulf. Despite this, Gulf elasmobranchs have been poorly researched, probably due to their low esteem as food. Information is scattered through a variety of literature, and only a handful of published works have been primarily concerned with aspects relevant to management. Key areas of concern include large reported landings by Iran; the export of fins to east Asian markets (particularly through the United Arab Emirates); potentially increasing demand for elasmobranchs for pharmaceutical products and human consumption; a reported change in elasmobranch community structure along the Iranian coast; and major degradation of the Gulf’s shallow, semi-enclosed environment. Priorities for research in the near future should include: resolution of taxonomic issues; species-level monitoring and reporting of fisheries landings by all Gulf states (including the species, pathways and fisheries involved in the fin trade locally); establishing the degree of connectivity of Gulf populations to those in adjacent waterbodies; and identification of key spatio-temporal sensitivities.

Spatial variation in parasite abundance: evidence of geographical population structuring in southern garfish Hyporhamphus melanochir

Southern garfish Hyporhamphus melanochir were examined for metazoan parasites from nine sites in three regions (Spencer Gulf, Gulf St Vincent and northern Kangaroo Island) in South Australia to document parasite assemblages, identify candidate species suitable for use as biological tags and investigate spatial variation in parasite abundance. Four ectoparasite and 10 endoparasite species were identified representing Cestoda, Trematoda, Monogenea, Nematoda, Acanthocephala, Copepoda and Isopoda. Lernaeenicus hemirhamphi, Micracanthorhynchina hemirhamphi, Mothocya halei and Philometra sp. were suggested for 'permanent' biological markers. Multivariate discriminant function analysis showed that most sites could be distinguished based on differences in parasite abundance. Four endoparasites (Conohelmins sp., Hysterothylacium sp., M. hemirhamphi and Philometra sp.) were most important for site characterization. Limited spatial variation in permanent endoparasite abundance among localities in northern Spencer Gulf provided evidence for a distinct northern Spencer Gulf population with little interregional mixing. In contrast, considerable spatial variation in permanent endoparasite abundance between localities sampled off Kangaroo Island implied limited local movement and suggested H. melanochir may comprise a metapopulation structure. These results largely align with recent evidence from otolith chemistry that indicates fine-scale geographical population structuring in South Australian waters.

Population genetic structure of the Silver Pomfret, Pampus argenteus (Euphrasén, 1788), in the Persian Gulf and the Sea of Oman as revealed by microsatellite variation

Microsatellite markers were applied to identify genetically distinct populations of the Silver Pomfret, Pampus argenteus (Euphrasén, 1788), in the Persian Gulf and the Sea of Oman. Biological data suggested that Iran, Iraq and Kuwait have one shared stock unit. Genomic DNAs from 125 specimens from five different geographic areas in Iran and Kuwait were extracted and PCR amplification performed. Seven loci with reasonable polymorphism were amplified. The results show that the average of observed heterozygosity was 0.53 while expected heterozygosity was 0.67. After applying the Hardy-Weinberg Equilibrium (HWE) test, some loci were found to deviate significantly from HWE in some populations in which deficiency of heterozygotes was apparent. The highest population differentiation was found between the Kuwait and Bushehr (population differentiation value F st=0.087, P≤0.01), while it was lowest between Chabahar and Bushehr (F st=0.021, P≤0.01). The highest genetic distance was found between Khuzestan and Chabahar (Genetic distance value: 0.269), and the lowest (0.075) between Bushehr and Chabahar. These data provide some new information on the genetic variation and differentiation within the Gulf population of Pampus argenteus and enhance our understanding of the ecology of this commercially important species.

Postpartum Mental Illness: Perspectives from an Arabian Gulf Population

There is growing awareness of the importance of mental health issues in the perinatal period in Western societies, but very little information is available from Muslim and Arab countries. Qualitative information gathered using focus group discussions of women of childbearing age is presented along with additional information obtained from key informant interviews with grandmothers, husbands, and health care professionals in the United Arab Emirates. The participants were women attending a public sector clinic in Al Ain, Abu Dhabi, and a private clinic in Dubai on a particular day. There were 19 women in the age range 17 to 46 years (M age = 29 yr.). The majority of the women who took part in the study did not recognize postnatal depression as a psychological issue but considered the problems a result of "evil eye" or "Jinn." The present findings suggest the need for initiating awareness programs among women and training of health professionals on the detection and management of postnatal depression.

Taxonomic status of the Guadalupe Darter, Percina apristis (Teleostei: Percidae)

Percina sciera apristis (Hubbs &amp; Hubbs) was described as a subspecies based on the hypothesis that the population in the Guadalupe River system was morphologically distinct from other populations and that populations geographically closest to the Guadalupe River were intergrades between P. s. sciera and P. s. apristis. Our data confirm the decision to recognize the population in the Guadalupe River as taxonomically distinct; however, western Gulf populations closest to the Guadalupe River do not show a consistent pattern of intermediacy in meristic variables. The Guadalupe population has extreme numbers of preopercular serrae, pored lateral-line scales, modified scales, caudal-peduncle scales, and anal rays. The most extreme trait is the number of preopercular serrae; 95% of individuals from the Guadalupe, but only 6% from other western Gulf drainages, have 0–3 serrae. Sixty-eight percent of Guadalupe individuals, but only 4% from elsewhere, have no serrae. These extreme values demonstrate that the Guadalupe population is genetically isolated and diagnosable as Percina apristis (Hubbs &amp; Hubbs), the Guadalupe Darter.

Genetic similarity of disjunct populations of the giant sea bass Stereolepis gigas

Sequence variation in nuclear and mitochondrial genes of the giant sea bass Stereolepis gigas collected from the Pacific coast and the northern Sea of Cortez was examined. Restriction fragment length polymorphism analysis and direct sequencing showed extremely low mtDNA sequence diversity (13 closely related haplotypes with no evidence of geographical population subdivision). The mitochondrial haplotype mismatch distribution is consistent with a population expansion following the Last Pleistocene glaciation. Differences in single nucleotide polymorphism frequencies between Pacific and Sea of Cortez populations were detected at two of four nuclear loci, which may reflect natural selection or genetic drift in populations with low effective numbers of males. Although Pacific coast and Sea of Cortez populations of giant sea bass do not exhibit the mitochondrial phylogenetic break characteristic of many species with disjunct Pacific and Gulf populations, the possibility of genetic differentiation at nuclear loci suggests that a cautious approach to broodstock selection for captive breeding and restoration programmes be exercised.

Behavior Patterns of Bottlenose Dolphins in San Luis Pass, Texas

Common bottlenose dolphins (Tursiops truncatus) are behaviorally flexible cetaceans that have adapted to a wide variety of habitats. In the San Luis Pass area near Galveston, Texas, there are two populations of bottlenose dolphins, distinguished through long-term photo-identification studies, which use adjacent habitat in different ways. A small resident population makes use of the shallow bay system, while the larger, more transient population remains outside the bay along the Gulf of Mexico coastline. A 13-mo study was conducted to examine the behavior of these populations and to explore the hypothesis that although they overlap geographically, each population utilizes the area differently. The behavior of focal groups was assessed by instantaneous sampling, and a time budget of each behavior per unit effort was calculated. When these populations mix in Gulf of Mexico waters, social activity and travel were the primary behaviors observed. Resident dolphins foraged predominantly in the bays and pass, and displayed group foraging behavior. In contrast, Gulf dolphins were only observed foraging in coastal waters, and did so individually. These behavioral differences may reflect strategies based on habitat variation, but may also be indicative of distinct social structures between resident and Gulf populations. There was a seasonal component to behavior and group size, with larger mixed groups and more social behavior occurring in summer. Finally, resident dolphin behavior varied by time of day, with a peak in foraging in the morning and socializing in the afternoon. The results of this study suggest that these adjacent groups are distinct populations that have partitioned their habitat into separate niches, and thus should be treated separately in management decisions.

GEOGRAPHIC VARIATION IN NUCLEAR GENES OF THE EASTERN OYSTER, CRASSOSTREA VIRGINICA GMELIN

Abstract The eastern oyster, Crassostrea virginica Gmelin, is a common inhabitant of estuarine and coastal waters from maritime Canada through the Gulf of Mexico. Because mitochondrial DNA haplotypes exhibit a distinct genetic break between Atlantic and Gulf oysters at Cape Canaveral, Florida, the degree of divergence between Atlantic and Gulf oysters in nuclear genes is less well known. We examined patterns of variation in four nuclear loci using restriction fragment analysis of amplified DNA (PCR-RFLP) in oysters (n = 317) from 16 locations spanning the geographic range of C. virginica. Marked differentiation was observed between Atlantic and Gulf populations, with smaller differences detected between North Atlantic and South Atlantic populations. Intermediate populations were observed in both eastern and northwest Florida. Regional population structure was also evident in the Gulf Coast, with Texas oysters highly divergent from all other populations.

HLA determinants of susceptibility to multiple sclerosis in an Arabian Gulf population.

An association between HLA antigens and susceptibility to multiple sclerosis (MS) has been established, especially in Caucasian populations. Such associations have not been as clearly defined in many Arab populations, where even the frequencies of specific HLA antigens remain unclear The study was designed to (i) investigate the frequencies of HLA Class I and II antigens in Kuwaiti Arabs with MS, and; (ii) assess possible inter-relationships between HLA Class II antigens and such clinical phenotypic variables in MS as age at onset, gender, disease subtype and scale of disability. HLA Class I (A, B, C) and Class II (DR, DQ) antigens' tissue-typing was performed by the standard complement-dependent microlymphocytotoxicity technique in two groups of age- and sex-matched Kuwaiti subjects: (i) 67 patients with definite MS (48 relapsing remitting, 19 relapsing-progressive) and (ii) 145 unrelated healthy controls. The frequencies of specific HLA types were then compared between patients with controls, and in the former, related to specified clinical parameters. The frequencies for the Class I antigens: A9, A10, A19, A33, B5 and CW4 appeared higher with the presence of MS, although the numbers of positive subjects were rather low. For the Class II antigens, frequencies of DR4, DQ5, DQ6, DQ7 and DQ8 were increased while those for DR6 and DR1 were decreased in the patients with MS. HLA types DR15 and DR4 were present at higher frequencies in patients with a younger age at disease onset; DR15 also appeared more frequent in the female patients. There is a trend towards an association between HLA Class II antigens (DR4, DQ6, DQ7 and DQ8) and MS in Kuwaiti subjects. Additionally, it appeared that DR4 and DR15 were more frequent in females and those with an early onset of the disease. These patterns of HLA Class II determinants of susceptibility to MS differ from reports in some other populations, and may reflect the recognized variability in genetic influence on HLA and disease expression.

Population divergence in the sinistral whelks of North America, with special reference to the east Florida ecotone

This study evaluated models of species relationships among sinistral whelks in the genus Busycon in the Atlantic and Gulf of Mexico. Gene frequencies at eight polymorphic allozyme loci, shell morphology, anatomy, and partial DNA sequences for the cytochrome c oxidase I (COI) mitochondrial gene were examined in eight populations, ranging from New Jersey to the Yucatan peninsula, and from the dextrally coiled sister taxon Busycon carica (Gmelin, 1791). Whelks were collected in 1997 and 1998. The maximum COI sequence divergence recorded among 32 sinistral individuals was 1.96%, which together with the absence of any gross or qualitative morphological differences, suggested all eight populations should be considered conspecific. High levels of divergence between the allopatric western Atlantic and Gulf of Mexico populations, as revealed by fixed or nearly fixed differences at several allozyme-encoding loci were interpreted as evidence that the east Florida ecotone constitutes a significant barrier to gene flow. Size trimming also revealed several significant quantitative differences in shell and radular morphology between the three pooled Atlantic populations and five pooled Gulf populations. The Yucatan sample was the most distinctive conchologically, with heavy spines and tumid ridges, possibly related to stone crab predation. Based on the evidence all left-handed whelks of North America should be referred to the oldest available nomen, Busycon perversum (Linne, 1758), with three subspecies, B. perversum perversum along the Yucatan peninsula, B. perversum sinistrum (Hollister, 1958) in the northern and eastern Gulf of Mexico, and B. perversum laeostomum (Kent, 1982) in the Atlantic.