Ontogeny of the feeding apparatus and sensory modalities: Relationship to habitat differentiation among early life history stage drums (Sciaenidae) in the Chesapeake Bay

Although the form and function of the structure of the feeding apparatus and diet are linked in adult fishes, it is often not clear when during ontogeny the ecomorphological patterns enable early life history stage fishes (ELHS) to partition their foraging niches and reduce competition. Sciaenid (family Sciaenidae) species exhibit variability in the structure of the feeding apparatus, which allows them to exploit more foraging habitats as adults than any other family in the Chesapeake Bay. In this study, ELHS and juvenile sciaenids representing three foraging guilds (pelagic: n=92, 2.9-48.2 mm SL; generalist: n=71, 4.3-53.8 mm SL; and benthic: n=75, 1.9-43.2 mm SL) were captured during weekly, shore-based ichthyoplankton and trawl surveys throughout the lower Chesapeake Bay, York River, and tidal inlets on Eastern Shore of Virginia. Stomachs were removed, specimens were cleared and double stained, and elements of the feeding apparatus were measured. A smaller subset of specimens (n=17) were stained using a 1% phosphotungstic acid solution and then scanned using micro-computed tomography to determine sensory modality in ELHS sciaenids representing the same foraging guilds. A dietary shift occurred first in pelagic sciaenids (16 mm SL), which corresponded to an expansion of sensory modalities, particularly gustation and audition that augment vision. The dietary shift was observed next in benthic sciaenids at 20 mm SL, which corresponded to the acquisition of oral and pharyngeal specializations suited to exploiting benthic prey even though they lacked sensory specializations. Finally, generalist sciaenids experienced a dietary shift at 35 mm SL, which occurred after the expansion of sensory modality (particularly vision, olfaction, gustation, and mechanoreception) but before specializations to the feeding apparatus were observed. Phylogenetic signal, measured as Pagel\u27s lambda, was also calculated for oral jaw elements using a molecular and a morphological topology to determine if evolutionary history may constrain the configuration of these elements and to understand how topology may influence the detected phylogenetic signal. Pagel\u27s lambda was low for pelagic sciaenids in premaxilla, lower jaw, and ascending process length, regardless of the topology used in the analysis. The signal was variable for benthic sciaenids depending on the topology used in the analysis; the signal was low when a morphological topology was used but was high for lower jaw and ascending process length when a molecular topology was used. In benthic sciaenids, Pagel\u27s lambda, was intermediate for premaxilla length when the molecular topology was used, suggesting that the length of the premaxilla is influenced by natural selection despite some phylogenetic constraints. Therefore, the morphological patterns detected in ELHS sciaenids are not constrained exclusively by evolutionary history and represent ecomorphological, which suggest that sciaenids are able to partition foraging in nursery habitats during these early stages

A taxonomy of explanations in a general practitioner clinic for patients with persistent “medically unexplained” physical symptoms

MSS1 and MSS2 were supported by grants from the Chief Scientist Office of the Scottish Government (references CZG/2/412 and CZH/4/945). We are grateful to the general practitioners and patients who participated in these studies.Peer reviewedPostprin

The long arm of childhood intelligence on terminal decline:Evidence from the Lothian Birth Cohort 1921

The current study investigates the heterogeneity of cognitive trajectories at the end of life by assigning individuals into groups according to their cognitive trajectories prior to death. It also examines the role of childhood intelligence and education on these trajectories and group membership. Participants were drawn from the Lothian Birth Cohort of 1921 (LBC1921), a longitudinal study of individuals with a mean age of 79 years at study entry, and observed up to a maximum of five times to their early 90s. Growth mixture modelling was employed to identify groups of individuals with similar trajectories of global cognitive function measured with the Mini-Mental State Examination (MMSE) in relation to time to death, accounting for childhood intelligence, education, the time to death from study entry, and health conditions (hypertension, diabetes and cardiovascular disease). Two distinct groups of individuals (classes) were identified: a smaller class (18% of the sample) of individuals whose MMSE scores dropped linearly with about 0.5 MMSE points per year closer to death, and a larger group (82% of the sample) with stable MMSE across the study period. Only childhood intelligence was found to be associated with an increased probability of belonging to the stable class of cognitive functioning prior to death (odds ratio=1.08, standard error=0.02, p≤.001). These findings support a protective role of childhood intelligence, a marker of cognitive reserve, against the loss of cognitive function prior to death. Our results also suggest that terminal decline is not necessarily a normative process

Influence of Central Pacific Oceanographic Conditions on the Potential Vertical Habitat of Four Tropical Tuna Species

Climate change has resulted in the geographic and vertical expansion of oxygen minimum zones but their impact on the vertical distribution of commercially important species, such as tunas, is not well understood. Although La Nina events are characterized by increased upwelling along the equator, the increased primary productivity and bacterial proliferation drive the expansion of oxygen minimum zones. Vertical habitat of four tropical tuna species were characterized using direct observations of the oceanographic conditions of the Central Pacific Ocean during the 2008 La Nina event and existing primary literature on temperature and dissolved oxygen physiological tolerances for these tunas. Concentrations of potential prey were estimated using Acoustic Doppler Current Profiler raw backscatter and surface zooplankton tows. Based on the oceanographic conditions observed from February to Tune, low dissolved oxygen levels, more so than low temperatures, were inferred to restrict the predicted vertical habitat of four commercially important tuna species (bigeye, yellowfin, skipjack, and albacore). During peak La Nina conditions, temperature and dissolved oxygen tolerance limits of all four tuna species were reached at approximately 200 m. Zooplankton and myctophid fish densities peaked in the upper 200 in between 0 degrees N and 5 degrees N, which corresponded to a region with a shallow thermochne (150 m). Our findings suggest the possibility that competition and susceptibility to surface fishing gears may be increased for tropical tunas during a strong La Nina event due to vertical habitat restrictions

Composition and temporal patterns of larval fish communities in Chesapeake and Delaware Bays, USA

Comparing larval fish assemblages in different estuaries provides insights about the coastal distribution of larval populations, larval transport, and adult spawning locations. We simultaneously compared the larval fish assemblages entering 2 Middle Atlantic Bight (MAB) estuaries(Delaware Bay and Chesapeake Bay, USA) through weekly sampling from 2007 to 2009. In total,43 taxa (32 families) and 36 taxa (24 families) were collected in Delaware and Chesapeake Bays,respectively. Mean taxonomic diversity, mean richness, and evenness were generally lower in Delaware Bay. Communities of both bays were dominated by Anchoaspp., Gobiosomaspp.,Micropogonias undulatus, and Brevoortia tyrannus; Paralichthys spp. was more abundant in Delaware Bay and Microgobius thalassinus was more abundant in Chesapeake Bay. Inter-annual variation in the larval fish communities was low at both sites, with a relatively consistent composition across years, but strong seasonal (intra-annual) variation in species composition occurred in both bays. Two groups were identified in Chesapeake Bay: a ‘winter’ group dominated by shelf-spawned species and a ‘summer’ group comprising obligate estuarine species and coastal species.In Delaware Bay, 4 groups were identified: a ‘summer’ group of mainly obligate estuarine fishes being replaced by a ‘fall’ group; ‘winter’ and ‘spring’ groups were dominated by shelf-spawned and obligate estuarine species, respectively. This study demonstrates that inexpensive and simultaneous sampling in different estuaries provides important insights into the variability in community structure of fish assemblages at large spatial scales

Lifecourse Activity Participation From Early, Mid, and Later Adulthood as Determinants of Cognitive Aging: The Lothian Birth Cohort 1921

OBJECTIVES: To examine potential sensitive periods for activity participation across adulthood to reduce cognitive decline and to determine whether associations persist after accounting for the lifetime stability of cognitive ability. METHOD: The Lothian Birth Cohort 1921 is a longitudinal study of cognitive aging. Participants were born in 1921 and most completed a mental ability test at the age of 11 years. Cognitive assessments were completed at mean ages 79 (N = 550), 83 (N = 321), 87 (N = 235), and 90 years (N = 129). Participants provided retrospective details of their activity participation for young (20–35 years), mid (40–55 years), and later adulthood (60–75 years), and contemporaneously at age 79. RESULTS: Associations between activity and the level of, and change in, cognitive ability in old age were examined with latent growth curve models. Accounting for demographics and childhood cognitive ability, engagement in leisure activities in midlife was positively associated with cognitive ability level (path coefficient = .32), whereas higher physical activity in later adulthood was associated with less cognitive decline (.27). DISCUSSION: The findings support a lifecourse approach in identifying determinants of cognitive aging; leisure and physical activity during different periods of adulthood may enhance cognitive abilities or reduce decline