Species redistribution creates unequal outcomes for multispecies fisheries under projected climate change.

Climate change drives species distribution shifts, affecting the availability of resources people rely upon for food and livelihoods. These impacts are complex, manifest at local scales, and have diverse effects across multiple species. However, for wild capture fisheries, current understanding is dominated by predictions for individual species at coarse spatial scales. We show that species-specific responses to localized environmental changes will alter the collection of co-occurring species within established fishing footprints along the U.S. West Coast. We demonstrate that availability of the most economically valuable, primary target species is highly likely to decline coastwide in response to warming and reduced oxygen concentrations, while availability of the most abundant, secondary target species will potentially increase. A spatial reshuffling of primary and secondary target species suggests regionally heterogeneous opportunities for fishers to adapt by changing where or what they fish. Developing foresight into the collective responses of species at local scales will enable more effective and tangible adaptation pathways for fishing communities.

Recommendations for quantifying and reducing uncertainty in climate projections of species distributions.

Projecting the future distributions of commercially and ecologically important species has become a critical approach for ecosystem managers to strategically anticipate change, but large uncertainties in projections limit climate adaptation planning. Although distribution projections are primarily used to understand the scope of potential change-rather than accurately predict specific outcomes-it is nonetheless essential to understand where and why projections can give implausible results and to identify which processes contribute to uncertainty. Here, we use a series of simulated species distributions, an ensemble of 252 species distribution models, and an ensemble of three regional ocean climate projections, to isolate the influences of uncertainty from earth system model spread and from ecological modeling. The simulations encompass marine species with different functional traits and ecological preferences to more broadly address resource manager and fishery stakeholder needs, and provide a simulated true state with which to evaluate projections. We present our results relative to the degree of environmental extrapolation from historical conditions, which helps facilitate interpretation by ecological modelers working in diverse systems. We found uncertainty associated with species distribution models can exceed uncertainty generated from diverging earth system models (up to 70% of total uncertainty by 2100), and that this result was consistent across species traits. Species distribution model uncertainty increased through time and was primarily related to the degree to which models extrapolated into novel environmental conditions but moderated by how well models captured the underlying dynamics driving species distributions. The predictive power of simulated species distribution models remained relatively high in the first 30 years of projections, in alignment with the time period in which stakeholders make strategic decisions based on climate information. By understanding sources of uncertainty, and how they change at different forecast horizons, we provide recommendations for projecting species distribution models under global climate change.

The shadow model: how and why small choices in spatially explicit species distribution models affect predictions.

The use of species distribution models (SDMs) has rapidly increased over the last decade, driven largely by increasing observational evidence of distributional shifts of terrestrial and aquatic populations. These models permit, for example, the quantification of range shifts, the estimation of species co-occurrence, and the association of habitat to species distribution and abundance. The increasing complexity of contemporary SDMs presents new challenges-as the choices among modeling options increase, it is essential to understand how these choices affect model outcomes. Using a combination of original analysis and literature review, we synthesize the effects of three common model choices in semi-parametric predictive process species distribution modeling: model structure, spatial extent of the data, and spatial scale of predictions. To illustrate the effects of these choices, we develop a case study centered around sablefish (Anoplopoma fimbria) distribution on the west coast of the USA. The three modeling choices represent decisions necessary in virtually all ecological applications of these methods, and are important because the consequences of these choices impact derived quantities of interest (e.g., estimates of population size and their management implications). Truncating the spatial extent of data near the observed range edge, or using a model that is misspecified in terms of covariates and spatial and spatiotemporal fields, led to bias in population biomass trends and mean distribution compared to estimates from models using the full dataset and appropriate model structure. In some cases, these suboptimal modeling decisions may be unavoidable, but understanding the tradeoffs of these choices and impacts on predictions is critical. We illustrate how seemingly small model choices, often made out of necessity or simplicity, can affect scientific advice informing management decisions-potentially leading to erroneous conclusions about changes in abundance or distribution and the precision of such estimates. For example, we show how incorrect decisions could cause overestimation of abundance, which could result in management advice resulting in overfishing. Based on these findings and literature gaps, we outline important frontiers in SDM development.

Limited evidence for sardine and anchovy asynchrony: re-examining an old story.

Asynchronous fluctuations in abundance between species with similar ecological roles can stabilize food webs and support coexistence. Sardine (Sardinops spp.) and anchovy (Engraulis spp.) have long been used as an example of this pattern because low-frequency variation in catches of these species appears to occur out of phase, suggesting that fisheries and generalist predators could be buffered against shifts in productivity of a single species. Using landings data and biomass and recruitment estimates from five regions, we find that species do not have equivalent peak abundances, suggesting that high abundance in one species does not compensate for low abundance in the other. We find that globally there is a stronger pattern of asynchrony in landings compared to biomass, such that landings data have exaggerated the patterns of asynchrony. Finally, we show that power to detect decadal asynchrony is poor, requiring a time series more than twice the length of the period of fluctuation. These results indicate that it is unlikely that the dynamics of these two species are compensatory enough to buffer fisheries and predators from changes in abundance, and that the measurements of asynchrony have largely been a statistical artefact of using short time series and landings data to infer ecology.

Old-Growth Fishes Become Scarce under Fishing.

Researchers have long recognized the importance of ecological differences at the species level in structuring natural communities yet until recently have often overlooked the influence of intraspecific trait variation, which can profoundly alter community dynamics [1]. Human extraction of living resources can reduce intraspecific trait variation by, for example, causing truncation of age and size structure of populations, where numbers of older individuals decline far more with exploitation than younger individuals. Age truncation can negatively affect population and community stability, increasing variability in population and community biomass [2-6], reducing productivity [7-10] and life-history diversity in traits such as the spatial and temporal pattern of reproduction and migration [4, 11-16]. Here, we quantified the extent of age truncation in 63 fished populations across five ocean regions, as measured by how much the proportions of fish in the oldest age groups declined over time. The proportion of individuals in the oldest age classes decreased significantly in 79% to 97% of populations (compared to historical or unfished values, respectively), and the magnitude of decline was greater than 90% in 32% to 41% of populations. The pervasiveness and intensity of age truncation indicates that fishing is likely reducing the stability of many marine communities. Our findings suggest that more emphasis should be given to management measures that reduce the impact of fishing on age truncation, including no-take areas, slot limits that prohibit fishing on all except a narrow range of fish sizes, and rotational harvesting.

An overview of burning mouth syndrome for the dermatologist.

Burning mouth syndrome is characterized by an idiopathic burning pain affecting the oral mucosa, with no clinically apparent changes. It can present to a variety of health professionals including dermatologists. This article summarizes the important aspects of the condition, including theories of pathogenesis, diagnosis and management.

Marine reserves can enhance ecological resilience.

The goals of ecosystem-based management (EBM) include protecting ecological resilience, the magnitude of a perturbation that a community can withstand and remain in a given state. As a tool to achieve this goal, no-take marine reserves may enhance resilience by protecting source populations or reduce it by concentrating fishing in harvested areas. Here, we test whether spatial management with marine reserves can increase ecological resilience compared to non-spatial (conventional) management using a dynamic model of a simplified fish community with structured predation and competition that causes alternative stable states. Relative to non-spatial management, reserves increase the resilience of the desired (predator-dominated) equilibrium state in both stochastic and deterministic environments, especially under intensive fishing. As a result, spatial management also increases the feasibility of restoring degraded (competitor-dominated) systems, particularly if combined with culling of competitors or stock enhancement of adult predators.

Beyond connectivity: how empirical methods can quantify population persistence to improve marine protected-area design.

Demographic connectivity is a fundamental process influencing the dynamics and persistence of spatially structured populations. Consequently, quantifying connectivity is essential for properly designing networks of protected areas so that they achieve their core ecological objective of maintaining population persistence. Recently, many empirical studies in marine systems have provided essential, and historically challenging to obtain, data on patterns of larval dispersal and export from marine protected areas (MPAs). Here, we review the empirical studies that have directly quantified the origins and destinations of individual larvae and assess those studies' relevance to the theory of population persistence and MPA design objectives. We found that empirical studies often do not measure or present quantities that are relevant to assessing population persistence, even though most studies were motivated or contextualized by MPA applications. Persistence of spatial populations, like nonspatial populations, depends on replacement, whether individuals reproduce enough in their lifetime to replace themselves. In spatial populations, one needs to account for the effect of larval dispersal on future recruitment back to the local population through local retention and other connectivity pathways. The most commonly reported descriptor of larval dispersal was the fraction of recruitment from local origin (self-recruitment). Self-recruitment does not inform persistence-based MPA design because it is a fraction of those arriving, not a fraction of those leaving (local retention), so contains no information on replacement. Some studies presented connectivity matrices, which can inform assessments of persistence with additional knowledge of survival and fecundity after recruitment. Some studies collected data in addition to larval dispersal that could inform assessments of population persistence but which were not presented in that way. We describe how three pieces of empirical information are needed to fully describe population persistence in a network of MPAs: (1) lifetime fecundity, (2) the proportion of larvae that are locally retained (or the full connectivity matrix), and (3) survival rate after recruitment. We conclude by linking theory and data to provide detailed guidance to empiricists and practitioners on field sampling design and data presentation that better informs the MPA objective of population persistence.

Comparative demography of skates: life-history correlates of productivity and implications for management.

Age-structured demographic models were constructed based on empirical estimates of longevity and maturity for five deepwater Bering Sea skates to investigate how observed differences in life history parameters affect population growth rates. Monte Carlo simulations were used to incorporate parameter uncertainty. Estimated population growth rates ranged from 1.045 to 1.129 yr(-1) and were lower than those reported for other Alaskan skates and most chondrichthyans. Population growth rates of these and other high-latitude skates increased with relative reproductive lifespan, but displayed no significant relationship with body size or depth distribution, suggesting that assemblage shifts may be difficult to predict for data-poor taxa. Elasticity analyses indicated that juvenile and adult survival had greater per-unit effects on population growth rates than did egg-case survival or fecundity. Population growth rate was affected more by uncertainty in age at maturity than maximum age. The results of this study indicate that if skates are deemed to be a management concern, gear modifications or depth-specific effort controls may be effective.

Retroperitoneal lymph node dissection for metastatic germ cell tumours.

INTRODUCTION: In the North Trent Cancer network (NTCN) patients requiring retroperitoneal lymphadenectomy for metastatic testicular cancer have been treated by vascular service since 1990. This paper reviews our experience and considers the case for involvement of vascular surgeons in the management of these tumours. PATIENTS AND METHODS: Patients referred by the NTCN to the vascular service for retroperitoneal lymphadenectomy between 1990 and 2009 were identified through a germ cell database. Data were supplemented by a review of case notes to record histology, intraoperative and postoperative details. RESULTS: A total of 64 patients were referred to the vascular service for retroperitoneal lymph node dissection, with a median age of 29 years (16-63 years) and a median follow-up of 4.9 years. Ten patients died: eight from tumour recurrence, one from septicaemia during chemotherapy and one by suicide. Of the 54 who survived, 7 were alive with residual masses and 47 patients were disease-free at the last follow-up. Sixteen patients required vascular procedures: four had aortic repair (fascia), three had aortic replacement (spiral graft), four had inferior vena cava resection, two had iliac artery replacement and two had iliac vein resection. CONCLUSIONS: Retroperitoneal lymph node dissection often involves mobilisation and/or the resection/replacement of major vessels. We recommend that a vascular surgeon should be a part of testicular germ cell multidisciplinary team.

Heregulin enhances regenerative proliferation in postnatal rat utricular sensory epithelium after ototoxic damage.

Hair cell loss due to acoustic and ototoxic damage often leads to hearing and balance impairments. Although a spontaneous event in chicks and lower vertebrates, hair cell replacement occurs at a much lower frequency in mammals presumably due to a very low rate of supporting cell proliferation following injury. We report here that heregulin, a member of the neuregulin family, dramatically enhances proliferation of supporting cells in postnatal rat utricular epithelial sheet cultures after gentamicin treatment, as revealed by bromo-deoxyuridine (BrdU) immunocytochemistry. A dose-dependent study shows that the maximal effects of heregulin are achieved at 3 nM. The mitogenic effects of heregulin are confirmed in utricular whole mount cultures. Autoradiography of the utricular whole mount cultures shows that heregulin also enhances the number of tritiated thymidine-labeled cells within the hair cell layer. TaqMan quantitative RT-PCR analysis and immunocytochemistry reveal that heregulin and its binding receptors (ErbB-2, ErbB-3 and ErbB-4) are expressed in the inner ear sensory epithelium. Of several ligands activating various ErbB receptors, including heregulin, neuregulin-3, beta-cellulin, heparin binding-epidermal growth factor (HB-EGF), transforming growth factor-alpha (TGF-alpha) and EGF, heregulin shows the most potent mitogenic effects on supporting cells. Because neuregulin-3 that signals only through ErbB-4 does not show an effect, these data suggest that activation of the ErbB-2-ErbB-3 heterodimeric complexes, rather than ErbB-4, is critical for the proliferative response in the utricular sensory epithelium. In addition, gentamicin treatment induces an upregulation of heregulin mRNA. Considered together, heregulin may play an important role in hair cell regeneration following ototoxic damage.

Distinct expression patterns of notch family receptors and ligands during development of the mammalian inner ear.

The cochlea and vestibular structures of the inner ear labyrinth develop from the otic capsule via step-wise regional and cell fate specification. Each inner ear structure contains a sensory epithelium, composed of hair cells, the mechanosensory transducers, and supporting cells. We examined the spatio-temporal expression of genes in the Notch signaling pathway, Notch receptors (Notch1-4) and two ligands, Jagged1 and Delta1, in the developing mammalian inner ear. Our results show that Notch1 and Jagged1 are first expressed in the otic vesicle, likely involved in differentiation of the VIIIth nerve ganglion neurons, and subsequently within the inner ear sensory epithelia, temporally coincident with initial hair cell differentiation. Notch1 expression is specific to hair cells and Jagged1 to supporting cells. Their expression persists into adult. Notch2, Notch3, Notch4, and Delta1 are excluded from the inner ear epithelia. These data support the hypothesis that Notch signaling is involved in hair cell differentiation during inner ear morphogenesis.

Establishment of conditionally immortalized rat utricular epithelial cell lines using a retrovirus-mediated gene transfer technique.

Supporting cells in the inner ear sensory epithelium are most likely hair cell progenitors. In an effort to establish an in vitro model system of hair cell differentiation, we developed immortalized epithelial cell lines by transferring the tsA58 allele of the SV40 large T antigen oncogene into neonatal rat utricular supporting cells using a retrovirus. The established cell lines have been stably maintained continuously for more than 25 passages and display many features similar to primary supporting cells. They grow in patches and assume a polygonal morphology. Immunocytochemical characterization of the established cell lines reveals that these cells can be labeled by epithelial cell markers, but not by fibroblast, glial or neuronal markers. The immortalized cells grow rapidly in serum medium at permissive temperature, but the majority cease proliferation when cultured in serum free medium at non-permissive temperature. These cells respond to mitogenic growth factors including bFGF, EGF and TGF-alpha and express growth factor receptors in a manner similar to the primary supporting cells. Furthermore, we find that the cells undergo a morphological differentiation when cultured in serum free medium at non-permissive temperature in the presence of bFGF. Under these conditions, the cells shrink in size, become elongated, and express early hair cell markers such as calretinin and calmodulin. The utricular epithelial cell line we have established may potentially provide an invaluable system for studying hair cell differentiation and regeneration.

Mammalian myosin I alpha is concentrated near the plasma membrane in nerve growth cones.

To determine if unconventional myosins play a role in nerve outgrowth, antibodies specific for rat brain derived mammalian myosin I alpha (MMI alpha) were used to label cultured rat superior cervical ganglion nerve cells. Observations were made at both the light and electron microscopic level of resolution using preparative procedures designed to enhance the ability to precisely determine the relationship between antibody label and cellular structures in order to map the distribution and structural association of this myosin. Immunofluorescence showed that MMI alpha has a punctate distribution throughout the nerve cell body, neurites, and growth cones. In growth cones, MMI alpha staining is sometimes elevated in thin peripheral regions of high actin content at the leading edge. Immunoelectron microscopy using colloidal gold conjugated antibodies showed that in growth cones MMI alpha is absent from membranous organelles and is concentrated primarily in the cell cortex adjacent to the cell membrane. The cortical label is equally distributed between upper and lower membranes. The plasma membrane association of the MMI alpha label persists under conditions in which the actin cytoskeleton is perturbed or removed, suggesting a direct association between a fraction of MMI alpha and the plasma membrane. MMI alpha label is also associated with the non-cortical actin cytoskeleton. Partial disruption of the actin cytoskeleton using cytochalasin B causes redistribution of only a subset of MMI alpha label. These data suggest a complex relationship between MMI alpha, the actin cytoskeleton, and the plasma membrane in the growth cone. In contrast to its localization in the growth cone, in neuronal cell bodies MMI alpha is also associated with tubulovesicular structures. This suggests that at this location MMI alpha may either act as an organelle motor or is passively transported to the plasma membrane on vesicles.

Comparison of the ability of freeze etch and freeze substitution to preserve actin filament structure.

In order to test the ability of freeze substitution to accurately preserve the ultrastructure of the actin component of the cytoskeleton, the structure of rotary shadowed actin filaments was compared following preparation by glutaraldehyde fixation and freeze etch or freeze substitution. Freeze substituted actin filaments were further processed by either etching away frozen organic solvent or critical-point-drying before rotary shadowing. Comparison of filament diameters showed no significant difference between actin filaments that were directly etched and those that were freeze substituted and then etched. However, freeze substituted and then critical-point-dried filaments were significantly larger in diameter than filaments that were directly etched in water. The long pitch (right-handed) two start helix was not affected by the different methods of preparation. However, the left-handed "genetic" helical repeat that was prominent in actin filaments prepared by freeze etch was more difficult to detect in freeze substituted specimen, especially following critical-point-drying. Although the organization and distribution of actin filaments in extracted cells was similar in both freeze substituted and freeze etched specimens, there were some detectable differences. In cells that were freeze substituted and then critical-point-dried, filaments appeared to intersect at greater angles and seemed more "taut." These results suggest that freeze substitution can preserve the overall morphology of actin filaments, but some chemical or physical modification of macromolecular surface structure may occur during the substitution process and these changes may be further exaggerated by subsequent processing steps.

Nerve growth cone lamellipodia contain two populations of actin filaments that differ in organization and polarity.

The organization and polarity of actin filaments in neuronal growth cones was studied with negative stain and freeze-etch EM using a permeabilization protocol that caused little detectable change in morphology when cultured nerve growth cones were observed by video-enhanced differential interference contrast microscopy. The lamellipodial actin cytoskeleton was composed of two distinct subpopulations: a population of 40-100-nm-wide filament bundles radiated from the leading edge, and a second population of branching short filaments filled the volume between the dorsal and ventral membrane surfaces. Together, the two populations formed the three-dimensional structural network seen within expanding lamellipodia. Interaction of the actin filaments with the ventral membrane surface occurred along the length of the filaments via membrane associated proteins. The long bundled filament population was primarily involved in these interactions. The filament tips of either population appeared to interact with the membrane only at the leading edge; this interaction was mediated by a globular Triton-insoluble material. Actin filament polarity was determined by decoration with myosin S1 or heavy meromyosin. Previous reports have suggested that the polarity of the actin filaments in motile cells is uniform, with the barbed ends toward the leading edge. We observed that the actin filament polarity within growth cone lamellipodia is not uniform; although the predominant orientation was with the barbed end toward the leading edge (47-56%), 22-25% of the filaments had the opposite orientation with their pointed ends toward the leading edge, and 19-31% ran parallel to the leading edge. The two actin filament populations display distinct polarity profiles: the longer filaments appear to be oriented predominantly with their barbed ends toward the leading edge, whereas the short filaments appear to be randomly oriented. The different length, organization and polarity of the two filament populations suggest that they differ in stability and function. The population of bundled long filaments, which appeared to be more ventrally located and in contact with membrane proteins, may be more stable than the population of short branched filaments. The location, organization, and polarity of the long bundled filaments suggest that they may be necessary for the expansion of lamellipodia and for the production of tension mediated by receptors to substrate adhesion molecules.

Isolation and molecular characterization of a highly polymorphic centromeric tandem repeat in the family Falconidae.

An abundant tandem repeat has been cloned from genomic DNA of the merlin (Falco columbarius). The cloned sequence is 174 bp in length, and maps by in situ hybridization to the centromeric regions of several of the large chromosomes within the merlin karyotype. Complementary sequences have been identified within a variety of falcon species; these sequences are either absent or in very low copy number in the family Accipitridae. The cloned merlin repeat reveals highly polymorphic restriction patterns in the peregrine falcon (Falco peregrinus). These polymorphisms, which have been shown to be stably inherited within a family of captive peregrines, can be used to differentiate the Greenland and Argentina populations of this endangered raptor species.