Temporal Patterns Of Recruitment Research Articles

Infraorbital nerve injury triggers sex-specific neuroimmune responses in the peripheral trigeminal pathway and common pain behaviours

Trigeminal neuropathic pain is emotionally distressing and disabling. It presents with allodynia, hyperalgesia and dysaesthesia. In preclinical models it has been assumed that cephalic nerve constriction injury shows identical molecular, cellular, and sex dependent neuroimmune changes as observed in extra-cephalic injury models. This study sought empirical evidence for such assumptions using the infraorbital nerve chronic constriction model (ION-CCI). We compared the behavioural consequences of nerve constriction with: (i) the temporal patterns of recruitment of macrophages and T-lymphocytes at the site of nerve injury and in the trigeminal ganglion; and (ii) the degree of demyelination and axonal reorganisation in the injured nerve. Our data demonstrated that simply testing for allodynia and hyperalgesia as is done in extra-cephalic neuropathic pain models does not provide access to the range of injury-specific nociceptive responses and behaviours reflective of the experience of trigeminal neuropathic pain. Similarly, trigeminal neuroimmune changes evoked by nerve injury are not the same as those identified in models of extra-cephalic neuropathy. Specifically, the timing, magnitude, and pattern of ION-CCI evoked macrophage and T-lymphocyte activity differs between the sexes.

Climate change triggered synchronous woody plants recruitment in the last two centuries in the treeline ecotone of the Northern Hemisphere

Climate change triggers several ecosystem responses, including woody plant encroachment.We analyse woody plant recruitment across the treeline ecotone (the forest-tundra ecotone) of the Northern Hemisphere (NH) over an extended period (1801–2010) and its relation with atmospheric CO2 and air temperature.We detected a synchronous trend of woody plant recruitment across the NH, indicating a major climatic and environmental change, triggered by a combination of CO2 fertilization and air temperature changes.The drivers of woody plant recruitment changed with time: CO2 fertilization was the main driver in the period 1801–1950, while air temperature was the main driver after 1950, despite the drastic acceleration of CO2 increase in the last decades. These data support the hypothesis that we are shifting from a fertilization-dominated to a warming-dominated period.The temporal patterns of woody plant recruitment are consistent with the occurrence of the 1980 regime shift, a major change occurred in the Earth's biophysical systems. Indeed, the recruitment drop promoted by the 1960s–1980s air cooling, was followed by an intensive recruitment increase triggered by the restart of air warming in the last decades.The largest sensitivity and fastest resilience of evergreen and Pinaceae to the restart of air warming allows to hypothesize that, among the woody plant functional and taxonomic groups, they could perform the largest expansion also in future decades.

Ageing of juvenile coral grouper (Plectropomus maculatus) reveals year-round spawning and recruitment: implications for seasonal closures.

Temporal patterns in spawning and juvenile recruitment can have major effects on population size and the demographic structure of coral reef fishes. For harvested species, these patterns are crucial in determining stock size and optimizing management strategies such as seasonal closures. For the commercially important coral grouper (Plectropomus spp.) on the Great Barrier Reef, histological studies indicate peak spawning around the summer new moons. Here we examine the timing of spawning activity for P. maculatus in the southern Great Barrier Reef by deriving age in days for 761 juvenile fish collected between 2007 and 2022, and back-calculating settlement and spawning dates. Age-length relationships were used to estimate spawning and settlement times for a further 1002 juveniles collected over this period. Unexpectedly, our findings indicate year-round spawning activity generates distinct recruitment cohorts that span several weeks to months. Peak spawning varied between years with no clear association with environmental cues, and little to no alignment with existing seasonal fisheries closures around the new moon. Given the variability and uncertainty in peak spawning times, this fishery may benefit from additional and longer seasonal closures, or alternative fisheries management strategies, to maximize the recruitment contribution from periods of greatest reproductive success.

Eastern oysters Crassostrea virginica settle near inlets in a lagoonal estuary: spatial and temporal distribution of recruitment in Mid-Atlantic Coastal Bays (Maryland, USA).

Declines of the Eastern oyster, Crassostrea virginica, and its numerous ecological benefits have spurred oyster restoration initiatives. Successful restoration of a self-sustaining oyster population requires evaluating the temporal and spatial patterns of recruitment (settlement and survival) of oyster larvae in the target waterbody. Restoration of the Eastern oyster population in the Maryland Coastal Bays (MCBs), USA, a shallow lagoonal estuary, is of interest to federal, state, and non-governmental, but the location and timing of natural recruitment is not known. We assessed the spatial and temporal variation in oyster larval recruitment throughout the MCBs using horizontal ceramic tiles and PVC plates. Newly settled oyster larvae (recruits) were monitored biweekly from June to September 2019 and 2020 at 12 sites in the MCBs and a comparison site in Wachapreague, Virginia. Water quality measurements collected included temperature, salinity, dissolved oxygen, pH, and turbidity. The objectives of this study were to determine (1) the most effective substrate and design for monitoring oyster recruitment, (2) the spatial and temporal distribution of oyster larval recruitment in the MCBs, and (3) patterns in oyster larval recruitment that would be applicable to other lagoonal estuaries. (1) Ceramic tiles were more effective than PVC plates for recruiting oyster larvae. (2) Peak settlement began during the period from late June through July, and oyster recruitment was greatest at sites closest to the Ocean City and Chincoteague inlets. (3) Areas near broodstock that have slow flushing rates to retain larvae may provide the best environments for recruitment of oysters to lagoonal estuaries. As the first study on oyster larval recruitment in the MCBs, our results provide insight into their spatial and temporal distribution, methods that can serve as a foundation for future recruitment studies in other lagoonal estuaries, and baseline data that can be used to inform stakeholders and evaluate the success of oyster restoration projects in MCBs.

Gonad development and recruitment pattern of the oysters Crassostrea ariakensis and Crassostrea sikamea in a subtropical bay in China

The extent of oyster stocks and their habitat loss experienced on the Chinese coasts suggests that oyster restoration will be necessary to rebuild direct fisheries and recover lost ecosystem services. Limited understanding of oyster biology and ecology is among the potential barriers to successful restoration along the Chinese coasts. At a natural oyster bed in Jiantiao Bay, Sanmen County, China, the study compared gonad development and spawn duration of the Sumonie oyster Crassostrea ariakensis and the Kumamoto oyster Crassostrea sikamea through histological sections from May 2020 to March 2021. Their temporal and vertical recruitment patterns were simultaneously observed along an increasing tidal elevation gradient (0.1 m, 0.6 m, 1.1 m, 1.6 m, 2.1 m). The gonad index did not differ between the oysters (P>0.05), with the maximum values in June–August, but C. sikamea had a longer spawning duration (May–December) than C. ariakensis (May–October). Crassostrea ariakensis recruited to only the lower 3 tidal zones (0.1 m, 0.6 m, 1.1 m), and its recruits varied linearly and significantly as an inverse function of tidal elevation. Significant 2nd degree polynomial fits best described the relationships for C. sikamea recruits and tidal elevation. The greatest recruits were commonly observed at the mid intertidal zones (0.6 m, 1.1 m and 1.6 m). An evident vertical settlement pattern emerged for C. sikamea at both 1-day and 3-day experiments; the greatest settlement rates occurred in the 1.6 m tidal zone, intermediate rates occurred in the 1.1 m and 0.6 m, the lowest rates occurred in the 0.1 m and 2.1 m. The study concluded that C. sikamea sustained longer spawning and recruitment durations than C. ariakensis, and a strong zonation pattern in recruitment emerged; C. sikamea achieved its maximum recruits in the mid-tidal zone, while the recruits of C. ariakensis linearly decreased with increasing tidal elevation.

Oyster and Barnacle Recruitment Dynamics on and Near a Natural Reef in China: Implications for Oyster Reef Restoration

Oysters and barnacles are dominant inhabitants of natural and restored oyster reefs around the world, and high areal coverage of barnacles at natural or restored reefs commonly decreases substrate accessibility for oyster settlement. The overall understanding of oyster and barnacle recruitment dynamics provides invaluable information on site selection and strategies employed for oyster reef restoration. This study documented the temporal and spatial patterns of oyster and barnacle recruitment on and near the largest natural intertidal oyster reef (Liyashan) in China during 2019–2020. The oyster Crassostrea sikamea recruitment appeared as a continuous process from June through late November or early December, with the peak in August. Greater recruits of oyster spat occurred on the sheltered inshore at the upstream of the natural oyster reef than on the reef and the nearby open coast (p < 0.05). The barnacle recruitment extended from spring to early winter, with mid-spring and mid-summer peaks. Conversely, higher barnacle recruitment appeared on the natural oyster reef and the nearby open coast than on the sheltered inshore. Across all the monitoring sites, the cumulative recruits of oysters in each of 2019 and 2020 was negatively correlated with those of barnacles (p < 0.05). The inshore sites (SH1 and SH2) with high oyster recruitment and low barnacle recruitment should be recognized as the natural spatfall sites for the natural oyster reef restoration. The separation in the recruitment peak between the oyster and the barnacle indicated that August was the most favorable window for capturing oyster spat through substratum addition to the water around the natural reef.

Spatial and Temporal Variation of Scleractinian Coral Recruitment in Balok Coastal Waters and Bidong Island, Malaysia

Understanding coral recruitment is important as increasing of regional decline of coral reef worldwide. This study aimed to investigate the spatial and temporal coral recruitment patterns around reef sites in Balok coastal waters and Bidong Island, Malaysia. Recruitment density was determined by quantifying number of coral recruits settled on the terra-cotta tiles and artificial reef settlement plates. In Balok coastal waters, a total of 159 coral recruits were counted with 0.09 ± 0.03 n/m2 mean recruitment density per plate, while in Bidong Island, a total of 319 coral recruits were counted with 0.19 ± 0.02 n/m2 mean recruitment density per plate. Coral recruits were dominated by genus Pocillopora followed by Stylopora and Seriatopora in Bidong. Meanwhile in Balok, genus Platygyra was dominant coral recruits followed by Porites and Fungia. Additionally, minor spawning event was predicted in Balok coastal waters in September due to increase number of Platygyra coral. Recruitment density varied significantly between locations, types of settlement plates and plate’s orientation at both study areas. Current findings highlighted the significant use of artificial reef plates to increase the chances of larval settlement. This research also provides important information in assessing coral resilience towards different environmental conditions between coastal and sheltered reef areas.

Recruitment of coral reef fishes along a cross-shelf gradient in the Red Sea peaks outside the hottest season

Knowledge on the early life history, ecology, and biology of marine species is crucial for future projections of the resilience of coral reef ecosystems and for adequate management strategies. A fundamental component of population dynamics is the recruitment of new individuals, and in some marine populations, this may be a limiting factor. Recruitment peaks of coral reef fishes commonly occur during the warmer months of the year in many subtropical and temperate locations worldwide. In the Red Sea, very little is known about the influence of temperature on reproductive patterns of coral reef fishes and studies on recruitment are missing. The Red Sea is one of the hottest and most isolated tropical seas in the world. We hypothesized that sea surface temperatures (SSTs) during the Red Sea’s hottest season may exceed the optimum for successful recruitment of some coral reef fishes, which therefore has to occur during other, cooler seasons, unlike recruitment among coral reef ecosystems around the world. We identified taxa among fish recruits by matching mitochondrial DNA sequences (using COI, commonly known as “barcoding”) and assessed potential biological and environmental drivers of recruitment. We studied three reefs located along a cross-shelf gradient for 12 consecutive months in the central Red Sea to capture seasonal changes in biotic and abiotic parameters along this gradient. Our results indicated that recruitment peaks did not occur during the hottest SSTs for most taxa, especially at the hottest inshore and mid-shelf reefs, and identified fish recruitment to be mainly and strongly correlated with the biomass of planktonic invertebrates. Moreover, temporal patterns of fish recruitment differed within and among taxonomic families among the reefs.

Rock-pools as nurseries for co-existing limpets: Spatial and temporal patterns of limpet recruitment

Rock-pools are considered to be important habitats for early shore-life of intertidal limpets. We investigated recruitment patterns of three co-existing limpet species in the region of Sines (SW Portugal): the patellids Patella depressa and Patella ulyssiponensis, and the siphonariid Siphonaria pectinata. Juvenile limpets (shell length ≤ 10 mm for P. depressa and ≤ 5 mm for S. pectinata) were counted in summer 2007 and winter 2009, in a wide range of intertidal habitats, on three natural shores (one shore inside the Port of Sines and two shores outside the Port, 4 and 9 km away). Temporal and among-shore patterns of abundance of recruits (shell length < 5 mm for all species) into mid-shore rock-pools were examined over quarterly periods, from May 2005 to July 2008. Despite a widespread distribution of P. depressa and S. pectinata juveniles, significantly higher juvenile abundance was mostly found in habitats of rock-pools (maxima of 94 and 92 juveniles in 15x15 cm, respectively, both in rock-pools at mid-shore). All species were found to recruit into mid-shore rock-pools year-round. Recruitment of both patellid species followed a similar seasonal pattern, being consistently low during all summer periods (maxima of 64 recruits of P. depressa during spring 2008 and 45 recruits of P. ulyssiponensis during spring 2007, both in 15x15 cm). High inter-annual variation was found in the intensity of recruitment of S. pectinata, with the yearly highest densities of recruits during summer or autumn periods (maximum of 134 recruits in 15x15 cm during summer 2005). Recruitment of all species was highest on the farthest shore from the Port. This study suggests the primacy of rock-pools as nurseries for both patellogastropod and pulmonate limpets and the value of these habitats for sustaining limpet populations on this coast, where rocky-shores have been gradually replaced by artificial structures with scarcity of rock-pools.

In vivo imaging of calcium and glutamate responses to intracortical microstimulation reveals distinct temporal responses of the neuropil and somatic compartments in layer II/III neurons

ObjectiveIntracortical microelectrode implants can generate a tissue response hallmarked by glial scarring and neuron cell death within 100–150 μm of the biomaterial device. Many have proposed that any performance decline in intracortical microstimulation (ICMS) due to this foreign body tissue response could be offset by increasing the stimulation amplitude. The mechanisms of this approach are unclear, however, as there has not been consensus on how increasing amplitude affects the spatial and temporal recruitment patterns of ICMS. ApproachWe clarify these unknowns using in vivo two-photon imaging of mice transgenically expressing the calcium sensor GCaMP6s in Thy1 neurons or virally expressing the glutamate sensor iGluSnFr in neurons. Calcium and neurotransmitter activity are tracked in the neuronal somas and neuropil during long-train stimulation in Layer II/III of somatosensory cortex. Main resultsNeural calcium activity and glutamate release are dense and strongest within 20–40 μm around the electrode, falling off with distance from the electrode. Neuronal calcium increases with higher amplitude stimulations. During prolonged stimulation trains, a sub-population of somas fail to maintain calcium activity. Interestingly, neuropil calcium activity is 3-fold less correlated to somatic calcium activity for cells that drop-out during the long stimulation train compared to cells that sustain activity throughout the train. Glutamate release is apparent only within 20 μm of the electrode and is sustained for at least 10s after cessation of the 15 and 20 μA stimulation train, but not lower amplitudes. SignificanceThese results demonstrate that increasing amplitude can increase the radius and intensity of neural recruitment, but it also alters the temporal response of some neurons. Further, dense glutamate release is highest within the first 20 μm of the electrode site even at high amplitudes, suggesting that there may be spatial limitations to the amplitude parameter space. The glutamate elevation outlasts stimulation, suggesting that high-amplitude stimulation may affect neurotransmitter re-uptake. This ultimately suggests that increasing the amplitude of ICMS device stimulation may fundamentally alter the temporal neural response, which could have implications for using amplitude to improve the ICMS effect or “offset” the effects of glial scarring.

Long‐term dynamics of shrub facilitation shape the mixing of evergreen and deciduous oaks in Mediterranean abandoned fields

Abstract Recovery of Mediterranean forests after field abandonment is a slow process, even without propagule limitations. This is mainly due to stressful conditions for seedling establishment. In this context, shrubs play a critical role in facilitating tree recruitment, but how this process unfolds after field abandonment is not entirely known. We evaluated the long‐term dynamics of facilitation by the nurse shrub Retama sphaerocarpa in the recruitment of two ecologically contrasting oaks, the evergreen Quercus ilex and the deciduous Quercus faginea. Thirty years after field abandonment, we dated shrubs and oaks established in an old field to estimate the annual recruitment rates and investigate temporal recruitment patterns. For oaks, we differentiated recruitment at two microsites: open areas or under shrub. To assess how nurse shrubs modulated environmental stressors, we modelled oak recruitment as a function of climatic variables. For the evergreen oak, we assessed these effects within each microsite. Finally, we estimated the annual interaction index between shrubs and evergreen oak juveniles as a function of climatic conditions. Each species showed different recruitment pulses during colonization. Recruitment rate was the highest for the shrub, followed by the evergreen oak. Oak colonization under shrubs was appreciable 20 years after field abandonment, when shrub cover reached 2.2%, and concentrated under medium and large shrubs older than 7 years. Shrubs not only accelerated evergreen oak colonization but also attenuated the fluctuations of recruitment pulses. For the evergreen oak, the interaction index indicated facilitation dominance in years with more arid summers (precipitation &lt; 47 mm and heat waves longer than 8 days) and competition in wetter summers. Synthesis. Oak colonization in Mediterranean abandoned fields progressed slowly, and only two decades after abandonment pioneer shrub population grew to a level in size and number that could effectively trigger facilitation and accelerate tree recruitment. The shrub nurse effect was unbalanced between oak species, only benefiting the evergreen oak, and it was more prevalent in arid years. Our study illustrates the build‐up of shrub facilitation during forest recolonization and the varying nature of this process among climatically different years and ecologically distinct species. This information provides insights for assessing and managing Mediterranean forest recovery.

Connectivity between spawning and nursery areas for Pacific cod (Gadus macrocephalus) in the Gulf of Alaska

We present the results of a study of the connectivity between Pacific cod spawning and nursery areas, and settlement of Pacific cod in the Gulf of Alaska. This work was conducted to address the hypothesis that spatial and temporal patterns of recruitment are related to variability in connectivity between spawning and nursery areas. To examine this hypothesis, we developed a Lagrangian, biophysical, individual-based model of Pacific cod early life history and dispersal using the Dispersal Model for Early Life Stages (DisMELS) framework. This model is driven by currents and scalars such as temperature from a version of the Regional Oceanographic Model System (ROMS) developed for the Gulf of Alaska. Results of our study show connectivity patterns predicted by the model that agree with our understanding (based on genetic analyses) that there is a high degree of localized retention in Pacific cod. The results indicate that the Shumagin Islands and Prince William Sound regions may serve as important collectors of Pacific cod recruits from upstream spawning areas. We also find correlations between individual-based model outputs and several large-scale climate indicators that appear to show settlement in several important nursery areas, and recruitment overall, are positively affected by slower gyre circulation in the Gulf of Alaska. We hypothesize that this is due to enhancement of retention, settlement in the Shumagin Island region, and reduction of transport of young cod out of the Gulf of Alaska to the southwest.

Recruitment and facilitation in Pinus hartwegii, a Mexican alpine treeline ecotone, with potential responses to climate warming

Under climate warming the presence of key microsite facilitators modify soil moisture levels associated with successful tree recruitment at the treeline ecotone ofPinus hartwegii. Alpine treelines in Mexico are represented by high-elevation forests dominated by P. hartwegii Ldl. To address the degree to which the presence of suitable microsite facilitators are factors for successful recruitment within the treeline ecotone of P. hartwegii and modulate their responses to climate warming, year of natural tree establishment, number of trees recruited, and the presence of shelter elements at different exposures of Monte Tlaloc (in the Trans-Mexican Volcanic System) were recorded. For tree recruitment and microsite facilitation we recorded each tree and the type of potentially protective elements that may improve microsite conditions within a total of 32 circular plots (r = 18 m) in the alpine treeline ecotone (above 4000 m). Temperatures for Monte Tlaloc at 4000 m were estimated using the thermal gradient for the study area, and standard dendrochronological methods and a regression model were used to date tree recruitment. Vector generalized linear models show that maximum growing season temperatures have significantly influenced the temporal pattern of tree recruitment in this system over the past 50 years, but this influence was mediated by the presence (or absence) of specific shelter elements (shrubs, soil depressions, rocks or bare soil) within a specific treeline ecotone exposure, also shaping the spatial pattern of tree recruitment. The response of the treeline ecotone to climate warming at local scales is qualitatively modified by the presence of microscale features, requiring sufficient soil moisture to be available on the site of recruitment.

Temporal patterns of recruitment and substrate use by the nonindigenous octocoral Stragulum bicolor van Ofwegen and Haddad, 2011 (Alcyonacea) in the Southern Brazilian Coast

Temporal patterns of recruitment and substrate use by the nonindigenous octocoral Stragulum bicolor van Ofwegen and Haddad, 2011 (Alcyonacea) in the Southern Brazilian Coast

Temporal variation in invertebrate recruitment on an Eastern Pacific coral reef

The recruitment of marine invertebrate larvae to coral reef ecosystems is critical for the continued productivity of these highly biodiverse habitats. Despite such importance, little is known about temporal variation patterns of invertebrate larval recruitment in coral reefs ecosystems, aside from studies focused only on reef corals themselves. Given this knowledge deficiency, recruitment onto dead coral branches was monitored over a one-year period in the Central Mexican Pacific, and recruit assemblage and density both changed over time. In particular, recruitment was higher in the warmer months, possibly due to reproductive processes and/or increases in metabolic rates associated with high temperatures and seasonal/local events such as upwellings that increase the food resources available for the recruits which just before the warm season, when the recruitment is more more prevalent during the warm season. The most common invertebrate recruits were malacostracans, ostracods, gastropods, maxillopods, and polychaetes, and foraminifers were commonly observed, as well. Future works in this region will seek to understand whether recruit density and diversity change in response to elevated temperatures associated with global climate change.

Small scale temporal patterns of recruitment and hatching of Atlantic horse mackerel (L.) at a nearshore reef area

AbstractAtlantic horse mackerel (Trachurus trachurus, Linnaeus, 1758) is a highly exploited species, common throughout the North‐East Atlantic. As a pelagic‐neritic fish it typically occurs over the shelf from the surface to 200 m deep on sandy bottoms. Most research has focused on distributions of adults or early life stages (eggs and larvae) of this species in offshore waters and only a few studies have reported the occurrence of early stages near the coast. However, these nearshore environments might be important for the early growth and survival of the Atlantic horse mackerel. In addition, little is known on how environmental processes might affect the early stages of this species. Here, we monitored weekly recruitment of horse mackerel to artificial substrates (SMURFS) deployed near the coast at both the surface and near the bottom, and back‐calculated hatching cohorts. The relationship of both recruitment and hatching patterns with environmental factors was investigated. From a total of 2,515 fish, 2,490 (99%) recruited to surface SMURFS. A GAM and GAMM analysis of the recruitment and hatching patterns, respectively, revealed a strong relationship with the lunar cycle and upwelling. Both recruitment and hatching showed lunar periodicity, with peaks near the new moon and revealed to be influenced negatively by upwelling. This study suggests that the nearshore environment might be an important nursery area for post‐larval and early juvenile Atlantic horse mackerel.

Muscle synergies are consistent across level and uphill treadmill running

This study aimed to identify muscle synergies of the lower limb during treadmill running on level and inclined ground. Eight subjects ran on a treadmill at three speeds (2.5, 3.3, and 4.1 m/s) and two grades (level and 10% grade). Surface electromyographic (EMG) signals were recorded from 10 muscles of the lower limb, including deeper muscles such as vastus intermedius, adductor magnus, and adductor longus. Muscle synergies were extracted applying a non-negative matrix factorization algorithm, and relative co-activations across muscles and the temporal recruitment pattern were identified by muscle synergy vector and synergy activation coefficient, respectively. The scalar product between pairs of synergy vectors and synergy activation coefficients during level and uphill running conditions were analyzed as a similarity index, with values above 0.8 recognized as similar. Approximately 4 muscle synergies controlled the majority of variability in 10 EMGs during running, and were common between level and uphill conditions. At each running speed, inter-condition similarity was observed in synergy vector (r > 0.83) and synergy activation coefficients (r > 0.84) at each type of synergy. These results suggest that types of synergy are consistent between level and uphill running.

Parrotfish recruitment revisited: a key role for sea surface currents

Despite considerable attention to the role of parrotfish assemblages in maintaining coral reef ecosystem integrity, little is known about the factors affecting parrotfish settlement, which could play an important role in structuring parrotfish assemblages. Here, I expand on a previous study that sought to identify environmental correlates of the temporal patterns of recruitment of Sparisoma parrotfishes onto standardized settlement units sampled at 52 consecutive 10-day intervals over an uninterrupted 17-month period on the west coast of Barbados (W.I.). By (1) including previously unavailable satellite-derived island-wide current speed data in the analyses and (2) using a more flexible (non-linear) analytical framework, the re-analysis increased the variance explained from 24% to 74%. Furthermore, island-wide current speed had stronger predictive power than all of the previously identified environmental correlates of Sparisoma recruitment, i.e. sea surface temperature and chlorophyll a concentration, and lunar phase, underscoring a dominant role for large-scale, transport-related physical processes in driving parrotfish settlement. Relationships between Sparisoma recruitment and the environmental correlates were better explained as non-linear functions, with a hump-shaped relationship for current speed. Most variability in current speed reflected external forcing due to the passage through Barbados of a large, slow-moving, low-salinity intrusion of South American riverine origin. Considering the high recruitment variance explained and that satellite-derived data on key environmental correlates are publicly available, prediction of temporal patterns of parrotfish settlement in Barbados might be more feasible than previously expected.

A Dendroecological Analysis of Forest Dynamics for Old-GrowthAbies-Tsuga-Quercuson the Boso Peninsula, Southeastern Japan

This study investigated the composition, age- and size-structure, and tree-ring relationships for an old-growth, warm-temperate, mixed-evergreen forest at the University of Tokyo Chiba Forest, Japan. A total of 32 tree species were recorded, which was dominated by Abies firma and Quercus acuta. Tsuga sieboldii dominated the recruitment after 1850, followed by Abies firma. After 1920, many individuals of Castanopsis, Cinnamomum, Cleyera and Quercus became established. The temporal pattern of conifer recruitment did not correspond to the record of strong wind events. Basal area increment in Abies firma and Castanopsis sieboldii trees increased throughout their lives, a trend not seen in the ring width index. Mean annual temperature was below the 100-year mean between 1920 and 1940 and 1960–1980, but increased rather abruptly after 1980. Mean annual precipitation decreased after 1960. Tree-ring releases are very common at the study forest, which are indicative of frequent small to moderate-sized disturbances. At least one release was recorded in every decade from 1890 to the present day, which is likely the primary causal factor promoting tree growth and recruitment. Our results suggest that early logging activities coupled with natural disturbances had a great influence on the developmental process and current structure of the study stand and that tree growth is varying in a manner consistent with forest dynamics.

Recruitment patterns in an intertidal species with low dispersal ability: the reef-building Dendropoma cristatum (Biondi, 1859) (Mollusca: Gastropoda)

In the Mediterranean, the gastropod Dendropoma cristatum (sin. D. petraeum (Monterosato, 1884)) is the primary builder of the vermetid reef, an intertidal bioconstruction of exceptional ecological importance. Despite awareness of the need for conservation of this key species, the biology of D. cristatum remains poorly understood. The recruitment of D. cristatum deserves particular attention because the absence of a planktonic larval stage limits its dispersal ability. We examined the temporal pattern of recruitment during the breeding season of D. cristatum from June to September in 2013. Specifically, we compared the two portions of the vermetid reef (i.e. the inner edge and the outer edge) at localities with different exposures to wave motion. The number of recruits peaked in July, when it was significantly higher in the outer than in the inner edge. No differences emerged between localities with different wave exposures; however, the width of the reef was significantly related to the exposure index. Although there are still several gaps in our knowledge of the recruitment dynamics of D. cristatum, this study contributes to characterising recruitment rate variation at small spatial and temporal scales.