Southern Limit Of Distribution Research Articles

Local variations in environmental parameters govern 50 years of the decline of Fucus guiryi populations in the Canary Islands (eastern Atlantic)

Fucus guiryi is a species strongly threatened by climate change, and the populations in its southern distribution limit are fast disappearing. However, the extinction of this species is not widespread, since there are small places where some populations still survive. In this study we explore the general regression trend of F. guiryi populations in Tenerife (Canary Islands), and compare the changes in the thallus morphology, abundance of individuals and biomass that have occurred in two of its populations over the last decades. Our results show that populations on the North and South of the island have followed different trajectories. Populations of F. guiryi in the North showed a slight regression, the thallus still have a similar size to the past and have numerous receptacles. On the contrary, those of the South are in a critical state, with a strong reduction in plant size and loss of reproductive capacity. The biomass of the southern populations has also been reduced by 90%. The increase in wind speed, sea surface temperature and air temperature were negatively related to the development of F. guiryi populations. Our results suggest a ‘site effect’, where the geography and local climatic conditions interact with the current global warming trend. In this sense, some places in the North of the island, with climatic conditions less adverse to F. guiryi growth, are acting as refugia.

Unraveling interactions: do temperature and competition with native species affect the performance of the non-indigenous sun coral Tubastraea coccinea?

The impact of invasive species has been increasing in recent decades due to globalization, threatening marine biodiversity. Tubastraea spp. (sun corals) have been spreading worldwide, showing rapid increases in abundance and/or spatial occupancy and adverse effects on recipient native ecosystems. In Brazil, they have become major invaders, extending discontinuously for more than 3000 km along the coast. Despite increased research efforts on sun coral ecology/biology over the last decade, information about the species’ environmental tolerance and interactions with native species is still scarce. In this context, temperature may be an important driver, as it affects species interactions, primarily through its influence on organismal physiology. Thus, in the present study we assessed the effects of temperature in the invasive T. coccinea and the native zoanthid Palythoa caribaeorum, as well as on their interactions, via a 3-week mesocosm experiment, exposing the species (individually and grafted together) to a temperature range of 16–31 °C. This was accompanied by measuring key physiological traits (metabolism, growth, feeding rates and competitive behavior) that underlie species performance, and hence, competitive strength. The results showed that at Arvoredo Island, Brazil, currently the southern distribution limit of both species, (1) T. coccinea exhibited limited capacity to adjust to sudden temperature changes, (2) T. coccinea’s physical attacks did not affect P. caribaeorum, but induced increased metabolic costs in the former, while triggering increased growth in the latter, leading to eventual overgrowth of the sun coral and (3) that temperature interacted synergistically with the presence of the competitor in both species under high-temperature stress. These findings suggest that T. coccinea’s successful invasion is mainly associated with r-selected life-history traits, rather than competitive strength or a high plasticity to temperature changes, and thus, communities with specific native competitors and/or a variable thermal regime may be more resistant to sun coral invasion.

Growth of Saccharina latissima (Laminariales, Phaeophyceae) cultivated offshore under exposed conditions

ABSTRACTImplementation of open sea seaweed aquaculture has been pursued in Europe for high biomass production to be used for different purposes, including the biorefinery pipeline. Offshore cultivation has been proposed to avoid conflict with other uses of coastal areas such as fishing and recreational activities, and preferably associated with other compatible activities such as wind energy production or fish aquaculture to optimise costs and operation. Saccharina latissima is a European kelp species that finds its southern distribution limit in northern Portugal and is considered a good candidate for commercial cultivation. The present work studied growth performance of this species in exposed conditions, at 5, 10 and 15 m depth from February until September. Photosynthetic performance was also assessed at those depths in summer. Saccharina latissima grew in offshore exposed conditions at the southern distribution limit of the species, with growth rates of 3.3%–4.5% day−1 between January and May, while withstanding high wave heights. Results indicate that for food applications the growing season in these conditions may be extended until May. If used for applications with less stringent demands for appearance – for example, feed or biofuels – harvest can be delayed further. Optimisation of technology and understanding the underlying biology of S. latissima is needed for cultivation in these conditions. This will include development of low-maintenance/high-resistance support structures and harvest techniques, in addition to strategies for early deployment to improve cultivation reliability and to extend the growth period.

Impact of temperature on the growth of a Neotropical tree species (Hymenaea courbaril, Fabaceae) at its southern distribution limit.

Widely distributed tree species usually face different growth conditions across gradients of climate variables. Hymenaea courbaril inhabits most of Neotropical lowlands, where its growth is limited by low precipitation under seasonal precipitation regimes. However, it is still unclear what are the drivers of growth variability at its distribution limits, where populations are most vulnerable to climate change. We evaluated the role of precipitation and temperature variability on the growth rate of two populations of H. courbaril at the southern limits of its occurrence. Sampling sites comprise two semi-deciduous forest fragments with weathered and chemically poor soils, similar temperature conditions, only differing in size and in precipitation regime. To achieve that goal, we built two tree-ring chronologies using standard dendrochronological methods, one with 21 trees (37 radii) and the other one with 13 trees (24 radii). First, we evaluated if site conditions would affect average growth patterns, and then, we tested the climate-growth relationships and the teleconnections with the Equatorial Pacific sea surface temperature (SST). The results show that trees display similar average growth rates throughout life without evidence of influence from differing fragment sizes. Nonetheless, precipitation positively influences annual growth in the drier site, while it has a negative effect on growth in the wetter site. In contrast to previous studies, temperature has a stronger influence than precipitation on the growth of these trees. Monthly, seasonal, and annual mean temperatures showed a negative influence on trees growth. The variability of the regional temperature and, consequently, of the growth rate of the trees is partially dependent on the SST of the Equatorial Pacific. In conclusion, this study shows that temperature is a key limiting growth factor for this species at its southern distribution limits and periods with warmer temperature will likely reduce annual growth rate.

Extreme Marine Heatwaves Alter Kelp Forest Community Near Its Equatorward Distribution Limit

Climate change is increasing the frequency and severity of marine heatwaves. A recent extreme warming event (2014-2016) of unprecedented magnitude and duration in the California Current System allowed us to evaluate the response of the kelp forest community near its southern (warm) distribution limit. We obtained sea surface temperatures for the northern Pacific of Baja California, Mexico, and collected kelp forest community data at three islands, before and after the warming event. The warming was the most intense and persistent event observed to date, with low-pass anomalies 1°C warmer than the previous extremes during the 1982-1984 and 1997-1998 El Ninos. The period between 2014-2017 accounted for ~50% of marine heatwaves days in the past 37 years, with the highest maximum temperature intensities peaking at 5.9°C above average temperatures for the period. We found significant declines in the number of Macrocystis pyrifera individuals, except at the northernmost island, and corresponding declines in the number of fronds per kelp individual. We also found significant changes in the community structure associated with the kelp beds: half of the fish and invertebrate species disappeared after the marine heatwaves, species with warmer affinities appeared or increased their abundance, and introduced algae, previously absent, appeared at all islands. Changes in subcanopy and understory algal assemblages were also evident; however, the response varied among islands. These results suggest that the effect of global warming can be more apparent in sensitive species, such as sessile invertebrates, and that warming-related impacts have the potential to facilitate the establishment of tropical and invasive species.

Summer drought and spring frost, but not their interaction, constrain European beech and Silver fir growth in their southern distribution limits

Climate warming has lengthened the growing season by advancing leaf unfolding in many temperate tree species. However, an earlier leaf unfolding increases also the risk of frost damage in spring which may reduce tree radial growth. In equatorward populations of temperate tree species, both late frosts and summer droughts impose two constraints to tree growth, but their effects on growth are understudied. We used a tree-ring network of 71 forests to evaluate the potential influence of late frosts and summer droughts on growth in two tree species that reach their southern distribution limits in north-eastern Spain: the deciduous European beech (Fagus sylvatica L.) and the evergreen Silver fir (Abies alba Mill). The occurrence of late frost events and summer drought was quantified by using a high-resolution daily temperature and precipitation dataset considering the period 1950–2012. Late frosts were defined as days with average temperature below 0 °C in the site-specific frost-free period, whereas drought was quantified using the 18 month-long August Standardized Precipitation Evapotranspiration Index (SPEI). The growth of European beech and Silver fir was reduced by the occurrence of both late frost events and summer drought. However, we did not find a significant interaction on growth of these two climate extremes. Beech was more negatively impacted by late frosts, whereas Silver fir was more impacted by summer drought. Further studies could use remote-sensing information or in situ phenological records to refine our frost index and better elucidate how late frosts affect growth, whether they interact with drought to constrain growth, and how resilience mechanisms related to post-frost refoliation operate in beech.

Photosynthetic activity including the thermal‐ and chilling‐light sensitivities of a temperate Japanese brown alga Sargassum macrocarpum

SUMMARYThe effects of irradiance, temperature, thermal‐ and chilling‐light sensitivities on the photosynthesis of a temperate alga, Sargassum macrocarpum (Fucales) were determined by a pulse amplitude modulation (PAM)‐chlorophyll fluorometer and dissolved oxygen sensors. Oxygenic photosynthesis–irradiance curves at 8, 20, and 28°C revealed that the maximum net photosynthetic rates (NP max) and saturation irradiance were highest at 28°C, and lowest at 8°C. Gross photosynthesis and dark respiration determined over a range of temperatures (8–36°C) at 300 μmol photons m−2 s−1 revealed that the maximum gross photosynthetic rate (GPmax) occurred at 27.8°C, which is consistent with the highest seawater temperature in the southern distributional limit of this species in Japan. Additionally, the maximum quantum yields of photosystem II (F v/F m) during the 72‐h temperature exposures were stable at 8–28°C, but suddenly dropped to zero at higher temperatures, indicative of PSII deactivation. Continuous exposure (12 h) to irradiance of 200 (low) and 1000 (high) μmol photons m−2 s−1 at 8, 20, and 28°C revealed greater declines in their effective quantum yields (Φ PSII) under high irradiance. While Φ PSII under low irradiance were very similar with the initial F v/F m under 20 and 28°C, values rapidly decreased with exposure duration at 8°C. At this temperature, F v/F m did not recover to initial values even after 12 h of dark acclimation. Final F v/F m of alga at 28°C under high irradiance treatment also did not recover, suggesting its sensitivity to photoinhibition at both low and high temperatures. These photosynthetic characteristics reflect both the adaptation of the species to the general environmental conditions, and its ability to acclimate to seasonal changes in seawater temperature within their geographical range of distribution.

Yield losses and electron transport rate as indicators of thermal stress in Fucus serratus (Ochrophyta)

Global warming is driving shifts in the geographical distribution of seaweeds, such as the contraction of the Southern limit of cold-temperate Atlantic macroalgae, including the foundation intertidal fucoid Fucus serratus. However, the ecophysiological mechanisms explaining the decline of seaweeds is not fully understood. In vivo chlorophyll a fluorescence is used as an estimator of photosynthetic activity and physiological state of seaweeds. Collected at its southern distribution limit, Fucus serratus was cultured for two weeks in different temperatures (from 8 to 30 °C with increase of 2 °C). Growth rate, reproductive stage and fluorescence parameters were measured as maximal quantum yield (Fv/Fm), Electron transport rate (ETR), non-photochemical quenching (NPQ) and the yield losses (YNO and YNPQ).At high temperature, the photosynthetic responses mimic the pattern of shade adapted plants, i.e., increase of photosynthetic efficiency (αETR) and decrease of irradiance for saturation of photosynthetic rate (EkETR). At low irradiances (<66 μmol m−2 s−1) and mainly at extreme temperatures (high and low), yield loss is dominated by YNO, suggesting heat dissipation due to closure of PSII reaction centers. However, at high irradiances (1150–1500 μmol m−2 s−1) and in a wide range of temperatures (8–28 °C), yield loss is mainly due to Y(NPQ), related to the energy dissipation as heat throughout regulated photoprotective NPQ mechanisms such as the xanthophyll cycle. The optimal temperature for growth was 14–20 °C as ETRmax, whereas Fv/Fm maintains high values in a wider range of temperatures compared to ETRmax and Yield losses, indicating that Fv/Fm is not a good parameter to discriminate the effect of temperature on algal production. We discuss the use of ETR and yield losses to relate photosynthesis with growth, survival or reproduction under stress conditions. Our study shows that warming can increase photoprotection through yield loss and decrease the photosynthetic activity in macroalgae.

The Effect of Past Forestry Activity on Mediterranean Sessile Oak Forests on the NE Iberian Peninsula

While the sessile oak (Quercus petraea) may be widely distributed across Europe, it is somewhat rare on the NE Iberian Peninsula, its southern distribution and xeric limit. Understanding the relationship this forest has with not only climate factors but also with past human activity is important. This study aims to analyze the species composition and structure of sessile oak forests that form the xeric limit populations as well as examine the effect environmental factors have on them. The work was focused on the southernmost sessile oak forest, the Montseny Massif populations, which have a marked environmental Mediterranean influence. The sessile oak forest types were defined from field inventories and a cluster analysis classified the inventoried stands into five forest types. The compositional differences among the forest types were the result of past land uses and the intensity of forestry activity 50 y ago. Furthermore, the species composition is influenced by environmental factors, because more hydric stress promotes Mediterranean species. The study concludes that sessile oak are recovering from past forestry activity.

Evidence that the Montseny Mountains are still a good climatic refugium for the southernmost silver fir forest on the Iberian Peninsula

Many European temperate tree species reach their southern distribution limits in the Mediterranean region, and ongoing climate change will further restrict their climatic niche in this area. In this study, we investigated the effects of forest management and climate change on tree growth and the spatial extension of a silver fir forest (Abies alba Mill.) located at the species’ southern distribution limit on the Iberian Peninsula (Montseny Mountains Natural Park, Spain). Different growth variables such as tree-ring width (RW), basal area increment (BAI), earlywood width (EwW) and latewood width (LwW) were assessed, and climate-growth relationships were established for the period 1914–2010.Our results revealed that the main growth reductions and releases in the raw tree-ring width series were related to both volcanic activity and intensive logging. Since the establishment of the Natural Park in 1977, RW series have levelled off, and this has translated into an increase in BAI. This positive performance may have also facilitated the spatial expansion of the stand. Low precipitation during spring and summer was found to be the most limiting factor for tree growth during the period 1914–2010. Temperature had only a minor influence on tree growth. LwW was the growth variable most sensitive to climatic conditions. Such sensitivity explained the decreasing LwW trend since 1975. In contrast, EwW mostly depended on the previous year’s climatic conditions, and was not climatically limited during the growing season, resulting in an increasing trend over the study period. However, the temporal instability of most of these climate-growth relations indicated that climate change might have been beneficial for tree performance. Past logging events have fostered tree growth in the stand due to the increase in the availability of water, light, and nutrients, potentially alleviating the negative impacts of climate change. Furthermore, it is possible that the increase in the EwW improved water transport in the silver firs, which may also have helped them to endure ongoing climate change. Therefore, it is crucial to assess the role of forest management, as well as the potential acclimation of the tree species when considering the effects of climate change.

Zostera marina meadows in the northwestern Spain: distribution, characteristics and anthropogenic pressures

Zostera marina meadows represent an important marine ecosystem in the North temperate region. They are common in the northwestern Spain, but their distribution and biological traits remain poorly studied. Improving the knowledge of eelgrasses and identifying potential impact sources is necessary to implement conservation programs. Distribution, cover, density, size and presence of flowers in plants of Z. marina along the northwestern Spain were studied. Furthermore, we analyzed shifts in their distribution, the major human-mediated pressures (shellfishing activities) and their protection status. The study area was divided in 14 sectors that were sampled between 2014 and 2017. The northwestern Spain hosts the majority (61.5%, covering 5.8 km2, 48 meadows) of the total extension of Z. marina meadows in the Iberian Peninsula. Our study revealed 13 meadows that were not recorded before. Conversely, the disappearance of seven previously reported meadows was detected. Cover and density of Z. marina was 51.2% ± 15.1 (n = 180) and 181.1 shoots m−2 ± 79.6, respectively. Length and width of leaves were 41.9 cm ± 13.2 (n = 1800) and 6.3 mm ± 0.7, respectively. Although 98% of Z. marina meadows (5.7 km2) were located within marine protected areas, 80% of the meadows (4.7 km2) are subjected to anthropogenic pressures related to shellfishing activities. Z. marina meadows from the northwestern Spain are particularly relevant for the conservation of the species at its southern distribution limit and specific conservation and monitoring plans should be implemented to ensure its persistence. We propose 15 meadows to be considered in future conservation plans that were selected among the ones not included at present in protected areas, and considering their vulnerability and the presence of other species with interest for conservation.

Climate and landscape changes as driving forces for future range shift in southern populations of the European badger

Human-Induced Rapid Environmental Change (HIREC), particularly climate change and habitat conversion, affects species distributions worldwide. Here, we aimed to (i) assess the factors that determine range patterns of European badger (Meles meles) at the southwestern edge of their distribution and (ii) forecast the possible impacts of future climate and landcover changes on those patterns. We surveyed 272 cells of 5 × 5 km, to assess badger presence and confirmed its occurrence in 95 cells (35%). Our models estimate that badger’s presence is promoted by the occurrence of herbaceous fields and shrublands (5%–10%), and low proportions of Eucalyptus plantations (<~15%). Regions with >50% of podzols and eruptive rocks, higher sheep/goat density (>4 ind/km2), an absence of cattle, intermediate precipitation regimes (800–1000 mm/year) and mild mean temperatures (15–16 °C) are also more likely to host badgers. We predict a decrease in favourability of southern areas for hosting badgers under forecasted climate and landcover change scenarios, which may lead to a northwards retraction of the species southern distribution limit, but the overall landscape favourability is predicted to slightly increase. The forecasted retraction may affect community functional integrity, as its role in southern ecological networks will be vacant.

Inferring the demographic history of Japanese cedar, Cryptomeria japonica, using amplicon sequencing.

The evolution of a species depends on multiple forces, such as demography and natural selection. To understand the trajectory and driving forces of evolution of a target species, it is first necessary to uncover that species' population history, such as past and present population sizes, subdivision and gene flow, by using appropriate genetic markers. Cryptomeria japonica is a long-lived monoecious conifer species that is distributed in Japan. There are two main lines (omote-sugi and ura-sugi), which are distinguished by apparent differences in morphological traits that may have contributed to their local adaptation. The evolution of these morphological traits seems to be related to past climatic changes in East Asia, but no precise estimate is available for the divergence time of these two lines and the subsequent population dynamics in this species. Here, we analyzed the nucleotide variations at 120 nuclear genes in 94 individuals by using amplicon sequencing in combination with high-throughput sequencing technologies. Our analysis indicated that the population on Yakushima Island, the southern distribution limit of C. japonica in Japan, diverged from the other populations 0.85 million years ago (MYA). The divergence time of the other populations on mainland Japan was estimated to be 0.32 MYA suggesting that the divergence of omote-sugi and ura-sugi might have occurred before the last glacial maximum. Although we found modest levels of gene flow between the present populations, the long-term isolation and environmental heterogeneity caused by climatic changes might have contributed to the differentiation of the lines and their local adaptation.

Is tree age or tree size reducing height increment in Abies alba Mill. at its southernmost distribution limit?

Conventional methods for estimating the current annual increment of stand volume are based on the uncertain assumption that height increment decreases with tree age. Conversely, size, rather than age, should be accounted for the observed senescence-related declines in relative growth rate and, consequently, implemented in silvicultural manuals. Results stem from a study on Abies alba Mill. at its southern limit of distribution. Many factors limit height increment when age and size increase in large-statured tree species. Height–diameter allometric relationships are commonly used measures of tree growth. In this study, we tested if tree age was the main factor affecting the reduction in height increment of silver fir trees (Abies alba Mill.), verifying also whether tree size had a significant role in ecophysiological-biomechanical limitations to tree growth. The study was carried out in a silver fir forest located in Southern Italy, at the southernmost distribution limit for this species. Through a stratified random sampling, 100 trees were selected. All the selected trees were then felled and the total tree height, height increments (internode distances), diameter at breast height, and diameter increments (ring widths) were measured. The analyses of allometric models and scaling coefficients showed that the correlation between tree age and height increment was not always significant. We may conclude that tree age did not statistically explain the decrease in height increment in older trees. Instead, the increase in tree size and related physiological processes (expressed as product between diameter at breast height and tree height) explained the reduction in height increment in older trees and was the main factor limiting height growth trends in marginal population of silver fir.

Geographically Structured Growth decline of Rear-Edge Iberian Fagus sylvatica Forests After the 1980s Shift Toward a Warmer Climate

Warming-related growth decrease on southern Fagus sylvatica forests has been observed in different regions; however, whether it is a generalized fact or not remains unclear. Here we investigate the geographical pattern on growth response of the southwestern European beech forests to the warming climate shift which started in the 1980s. We sampled 15 beech forests (215 trees) across four climatically contrasting regions (Mediterranean, Pyrenean, low- and high-elevation Atlantic areas) near the southern distribution limit of the species in the Iberian Peninsula. Dendrochronological analyses were carried out to evaluate the growth of European beech since the 1950s. Growth responses quantified as pointer years, abrupt growth changes and long-term growth trends were compared between periods (before and after the 1980s climate shift), geographical regions and tree sizes. Analyses of the studied variables indicated a growth decrease in basal area increment after the climate shift in three of the four studied regions. Pyrenean stands were not negatively influenced by the climate shift, although an increase in the frequency of negative abrupt growth changes was also found there. Growth after the climate shift presented divergent patterns depending on the geographical region. Although Mediterranean and Atlantic stands presented different indicators of constrained growth, Pyrenean stands showed rising long-term growth trends. Such results suggest that regional characteristics differentially determine the growth response of the southern European beech forests to recent warming periods. Iberian beech forests located at the Pyrenees would benefit from forecasted warming conditions, whereas Atlantic and Mediterranean forests would be more prone to suffer warming-related growth decline.

Spatio-temporal variability of wrack abundance and composition along the north Portuguese sandy beaches

Spatio-temporal variability of wrack abundance and composition along the north Portuguese sandy beaches

Biobanking of local seaweed species to support conservation and commercial aquaculture: Saccharina latissima at its southern distribution limit.

Biobanking of local seaweed species to support conservation and commercial aquaculture: Saccharina latissima at its southern distribution limit.

Genomic Prediction of Growth and Stem Quality Traits in Eucalyptus globulus Labill. at Its Southernmost Distribution Limit in Chile

The present study was undertaken to examine the ability of different genomic selection (GS) models to predict growth traits (diameter at breast height, tree height and wood volume), stem straightness and branching quality of Eucalyptus globulus Labill. trees using a genome-wide Single Nucleotide Polymorphism (SNP) chip (60 K), in one of the southernmost progeny trials of the species, close to its southern distribution limit in Chile. The GS methods examined were Ridge Regression-BLUP (RRBLUP), Bayes-A, Bayes-B, Bayesian least absolute shrinkage and selection operator (BLASSO), principal component regression (PCR), supervised PCR and a variant of the RRBLUP method that involves the previous selection of predictor variables (RRBLUP-B). RRBLUP-B and supervised PCR models presented the greatest predictive ability (PA), followed by the PCR method, for most of the traits studied. The highest PA was obtained for the branching quality (~0.7). For the growth traits, the maximum values of PA varied from 0.43 to 0.54, while for stem straightness, the maximum value of PA reached 0.62 (supervised PCR). The study population presented a more extended linkage disequilibrium (LD) than other populations of E. globulus previously studied. The genome-wide LD decayed rapidly within 0.76 Mbp (threshold value of r2 = 0.1). The average LD on all chromosomes was r2 = 0.09. In addition, the 0.15% of total pairs of linked SNPs were in a complete LD (r2 = 1), and the 3% had an r2 value &gt;0.5. Genomic prediction, which is based on the reduction in dimensionality and variable selection may be a promising method, considering the early growth of the trees and the low-to-moderate values of heritability found in the traits evaluated. These findings provide new understanding of how develop novel breeding strategies for tree improvement of E. globulus at its southernmost range limit in Chile, which could represent new opportunities for forest planting that can benefit the local economy.

Biological aspects of the butterfly kingfish Gasterochisma melampus: distribution, total catch, size composition and CPUE

Biological aspects of butterfly kingfish Gasterochisma melampus were examined using Japanese longline fishery data and research data collected for over 20 years. Butterfly kingfish were distributed in a continuous band around the circumpolar region between 35°S and 45°S. The southern limit of distribution corresponded with the sub-Antarctic front. The estimated global total annual catch for butterfly kingfish ranged from 613 to 3699 t (mean 1859 t) with Japan taking the largest proportion of the total catch. Large, adult butterfly kingfish spawn in the south-eastern Pacific, whereas smaller, immature fish are distributed in feeding grounds in the area extending across the Atlantic and Indian Oceans to the south-western Pacific Ocean. Catch per unit effort (CPUE) data for fish in the feeding grounds from 1993 to 2016 were compared with the CPUE value from 1970. These data indicate that the stock is currently not likely to be depleted.

Fishermen do more than fish: local ecological knowledge of raftsmen about the arboreal species used to construct rafts (Bahia, Brazil)

BackgroundTraditional raft (jangada), piúba wood raft (jangada de pau de piúba), six-log raft (jangada de seis paus), and wooden raft (jangada de pau) are some of the names given to the traditional Brazilian watercrafts created from the buoyancy of bound logs. The traditional raft is a watercraft used and built by artisan fishermen who have, throughout generations, kept and improved knowledge related to this practice and the use of the plant species they need as raw materials. Active groups of these fishermen and their watercrafts are distributed along 200 km of the coast of the state of Bahia. The fishermen interviewed in this study are at the southern limit of distribution for the use of this type of vessel.MethodsThis study aimed to characterize the use of the arboreal species applied in the construction of the traditional raft in the municipalities of Uruçuca, Ilhéus, and Canavieiras in the southern State of Bahia, Brazil. For this purpose, structured and semi-structured interviews were individually conducted with 36 fishermen, and walking tours were conducted with specialists in the construction of the watercraft.ResultsWe observed that the raftsmen use 21 species to construct the traditional raft. The features of the wood, such as density, flexibility, and availability, are the main criteria applied to choose the arboreal species. Some species are preferred, such as pau de jangada (Apeiba tibourbou) and biriba (Eschweilera ovata), which are the most frequently employed in watercraft manufacturing.ConclusionsThe southern Bahia population is familiar with the different tree species that are linked to their fishing activities. The main link between the fishermen and the useful species is present in the practice of raft construction. Currently, the restricted access to raw materials limits this practice, which consequently results in the cultural erosion of this community.