Potential changes in larval dispersal and alongshore connectivity on the central Chilean coast due to an altered wind climate

14 pages, 8 figuresClimate change is likely to result in significant alterations in the atmospheric and oceanic circulation, which may, as a result, affect species that depend on an ocean-driven nutrient supply and particularly those that possess a dispersal phase in their life history. In this paper we investigate the potential changes in larval dispersal and connectivity of marine populations on the Chilean coast due to altered wind forcing consistent with a future climate change scenario. Numerical ocean simulations forced by modeled present-day and future winds under the Intergovernmental Panel on Climate Change A2 scenario are used to investigate the potential changes in nearshore circulation. Off-line particle-tracking simulations are then analyzed to determine resulting changes in larval dispersal and connectivity under each scenario as a function of pelagic larval duration and for two different possible larval behaviors: passive and vertical migration. It is found that the projected future winds drive an intensification of the upwelling circulation, which results in a relative annual mean surface cooling of 1°C over much of the domain, an increase in the strength of the poleward undercurrent, and a more energetic mesoscale eddy field. Neutrally buoyant larvae are inferred to have low rates of settlement under present conditions and are more strongly disadvantaged under the simulated future conditions than larvae with vertically migrating behavior. Larvae that posses an ability to sink out of the surface Ekman layer are found to have higher rates of settlement under present conditions and are, in fact, favored slightly in the A2 scenario for pelagic larval durations longer than 2 days. This behavior-dependent response to future conditions may potentially drive a reorganization of coastal communitiesSupport for this study was provided through the Laboratorio Internacional en Cambio Global (LINCGlobal) and CMA through Fondecyt grant 1100646. We thank Rene Garreaud from the Universidad de Chile for providing the output from the PRECIS model simulations and for his useful comments. The authors thankfully acknowledge the computer resources, technical expertise, and assistance provided by the Barcelona Supercomputing Center. S.A.N. acknowledges support by FONDAP-FONDECYT grant 15001–0001 to CASEBPeer Reviewe

Integration of biophysical connectivity in the spatial optimization of coastal ecosystem services

Ecological connectivity in coastal oceanic waters is mediated by dispersion of the early life stages of marine organisms and conditions the structure of biological communities and the provision of ecosystem services. Integrated management strategies aimed at ensuring long-term service provision to society do not currently consider the importance of dispersal and larval connectivity. A spatial optimization model is introduced to maximise the potential provision of ecosystem services in coastal areas by accounting for the role of dispersal and larval connectivity. The approach combines a validated coastal circulation model that reproduces realistic patterns of larval transport along the coast, which ultimately conditions the biological connectivity and productivity of an area, with additional spatial layers describing potential ecosystem services. The spatial optimization exercise was tested along the coast of Central Chile, a highly productive area dominated by the Humboldt Current. Results show it is unnecessary to relocate existing management areas, as increasing no-take areas by 10% could maximise ecosystem service provision, while improving the spatial representativeness of protected areas and minimizing social conflicts. The location of protected areas was underrepresented in some sections of the study domain, principally due to the restriction of the model to rocky subtidal habitats. Future model developments should encompass the diversity of coastal ecosystems and human activities to inform integrative spatial management. Nevertheless, the spatial optimization model is innovative not only for its integrated ecosystem perspective, but also because it demonstrates that it is possible to incorporate time-varying biophysical connectivity within the optimization problem, thereby linking the dynamics of exploited populations produced by the spatial management regime.Comment: 30 pages, 5 figures, 2 tables; 1 graphical abstract. In this version: numbering of figures corrected, updated figure 2, typos corrected and references fixe

Latitudinal variation in maternal investment traits of the kelp crab Taliepus dentatus along the coast of Chile

Maternal investment (MI), the energy allocated by mothers to offspring, has important effects on the life-history traits of marine organisms. Variation in such traits shows strong correlation with latitude for several marine taxa (Thorson’s rule). Large-scale latitudinal variation in MI within a single species suggests population genetic divergence, while temporal changes in MI, rather, reflect plasticity. At higher latitudes (i.e., colder waters), traits associated with MI (brood weight, fecundity, egg volume, and energy content) increase. To identify phenotypic plasticity along a latitudinal gradient in MI traits (brood weight, egg volume, density number, and egg lipid composition), five populations of the kelp crab Taliepus dentatus along the coast of Chile (30°S–42°S) were investigated during the summer (December–February) and winter months (June–August) of 2015–2016. Despite this wide latitudinal range, the sea surface temperature (SST) difference between the northernmost and the southernmost sites was only approximately 2.0 °C in winter and 5.5 °C in summer. In summer, when latitudinal variation in SST was highest, brood weight, egg density, fecundity, and egg lipids increased with latitude, while egg volume decreased. No trends in MI were observed in winter when the SST gradient was almost non-existent. These results suggest that the relationship between MI and latitude is shaped by temperature rather than being site-specific. The seasonality of latitudinal MI traits also suggests a trade-off between the costs of female maintenance and/or brooding behaviours and MI. When investigating latitudinal and temporal variation in marine brooder MI, the effect of temperature on life-history traits and the associated costs of female brooding should be quantified

A parametrization for the symbols of a Hankel type operator

Hankel operators and their symbols, as generalized by V. Pták and P. Vrbová, are considered. In this more general framework, a linear operator X from a Hilbert space H1 to a Hilbert space H2 is said to be a Hankel operator for given contractions T1 on H1 and T2 on H2 if, and only if, XT ∗ 1 = T2X and X satisfies a boundedness condition that depends on the unitary parts of the minimal isometric dilations V1 of T1 and V2 of T2. A Hankel symbol of X is a dilation Z of X, with a certain norm constraint, such that ZV ∗ 1 = V2Z. The boundedness condition imposed to X has revealed to be essential, indeed necessary and sufficient, for X to admit Hankel symbols. As for a description of the symbols of X, this work provides a parametric labeling of all of them by means of Schur like formula. As a by-product, a new proof of the existence of Hankel symbols is obtained. The proof is established by associating to X, T1 and T2 a suitable isometry V so that there is a bijective correspondence between the symbols of X and the family of all minimal unitary extensions of V.Ministerio de Ciencia y TecnologíaJunta de AndalucíaFondo Nacional de Ciencia, Tecnología e Innovación (Venezuela

A.: Interhemispheric comparison of recruitment to intertidal communities: Pattern persistence and scales of variation

Abstract. Recruitment variation can be a major source of fluctuation in populations and communities, making it difficult to generalize results. Determining the scales of variation and whether spatial patterns in the supply of individuals are persistent over time can provide insight into spatial generality and the application of conservation and metacommunity models. We examined these issues using eight-year-long data sets of monthly recruitment of intertidal mussels (Mytilus spp., Perumytilus purpuratus, Semimytilus algosus, Brachidontes granulata) and barnacles (Balanus glandula, Chthamalus dalli, Jehlius cirratus, Notochthamalus scabrosus) at sites spanning .900 km along the coasts of Oregon-northern California (OR-NCA, 45.47-39.438 N) and central Chile (CC, 29.5-34.658 S). We evaluated four general ''null'' hypotheses: that despite different phylogenies and great spatial separation of these taxa, their similar life history strategies and environmental settings lead to similar patterns of recruitment (1) between hemispheres, (2) in time, (3) in space, and (4) at larger and smaller spatial scales. Hypothesis 1 was rejected: along the OR-NCA coast, rates of recruitment were between two and three orders of magnitude higher, and patterns of seasonality were generally stronger and more coherent across space and time than along CC. Surprisingly, however, further analysis revealed regularities in both time and space for all species, supporting hypotheses 2 and 3. Temporal decorrelation scales were 1-3 months, and characteristic spatial scales of recruitment were ;250 km. Contrary to hypothesis 4, for the ecologically dominant species in both hemispheres, recruitment was remarkably persistent at larger mesoscales (kilometers) but was highly stochastic at smaller microscales (meters). Across species, increased recruitment variation at large scales was positively associated with increased persistence. Our results have several implications. Although the two regions span distinct latitudinal ranges, potential forcing processes behind these patterns include similar large-scale climates and topographically locked hydrographic features, such as upwelling. Further, spatial persistence of the recruitment patterns of most species at the mesoscale supports the view that marine protected areas can be powerful conservation and management tools. Finally, persistent and yet contrasting spatial patterns of recruitment among competing species suggest that recent metacommunity models might provide useful representations of the mechanisms involved in species coexistence

Uneven abundance of the invasive sun coral over habitat patches of different orientation: An outcome of larval or later benthic processes?

Larval behavior in the water column and preference among natural benthic habitats are known to determine initial spatial distribution patterns in several sessile marine invertebrates. Such larval attributes can be adaptive, promoting adult benthic distributions which maximize their fitness. Further benthic processes may, however, substantially change initial distribution of settlers. In this study, we first characterized spatial distributions of adult colonies and single-polyp recruits of the invasive azooxanthellate coral Tubastraea coccinea over substrates of different orientation, and evaluated their consistency at both small (several tens of meters) and intermediate (a few km) spatial scales. We then assessed, through field and laboratory experiments, larval preferences and relative settlement and recruitment rates on surfaces with different orientations to determine whether processes taking place during the larval and early post-larval stages could help explain the distribution patterns of recruits and adult colonies. Results suggest that larval passive buoyancy and active larval behavior, unrelated to light conditions, determine a clear settlement distribution pattern, in which the density of settlers is highest at undersurfaces and almost nil at upward facing horizontal substrates. Except for an almost absence of settlers, recruits and adult individuals on upward facing horizontal habitat, there is substantial mismatch between the distribution of settlers and that of recruits and adult colonies. The latter were also common in vertical substrate in the field. We speculate that coastal runoff at the study area and subsequent sedimentation may inhibit coral development on flat upward facing habitat, and that competitive interference and pre-emptive interactions with other azooxanthellate corals could constrain abundance of T. coccinea in underface horizontal habitat.CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior)FAPESP (Fundação de Apoio à Pesquisa do Estado de São Paulo)Research Centre for Marine Biodiversity of theUniversity of São Paulo (NP-Biomar/USP

Temporal variation in richness and composition of recruits in a diverse cnidarian assemblage of subtropical Brazil

Many studies have shown that the processes of colonization of new marine substrata, from settlement to recruitment, can leave long and lasting signals on the richness, composition and general structure of natural epifaunal assemblages. Systematic descriptions of temporal variability in patterns of richness and structure of recruits are scarce, partly because of logistical difficulties of working with multispecies assemblages of recruits. Here we quantify temporal variation in recruit richness, composition and structure of a rich cnidarian assemblage in southeastern Brazil, and evaluate the effect of microhabitat type and time of submersion on these patterns. We conclude that hydrozoan (the prevailing cnidarians in this assemblage) species richness occurs in a temporally bimodal pattern, with the majority of species divided between year-round recruiting species and temporally infrequently, non-seasonal species. This pattern does not depend on the species local abundance, and suggests that local species richness may be better estimated by increasing sampling efforts over time. Moreover, time since substrate submersion had no effect on species richness, but influences species composition, suggesting constant changes in the assemblage instead of accumulation of species through time. Finally, microhabitat variation, measured as differences between sheltered and exposed surfaces, despite influencing species' abundances, was not important for species richness.We thank Alvaro Migotto and Centro de Biologia Marinha (CEBIMar) of the Universidade de São Paulo for offering laboratory support during data collection, the Ilhabela Yacht Club for allowing the sampling in the marina, Thais P. Miranda, Amanda F. Cunha and María de los Angeles Becerríl for sharing their knowledge on hydrozoans, James Roper for providing language assistance, Rosana Rocha and Tito Lotufo for their contributions throughout the study, and an anonymous reviewer for the valuable comments. MOF had a MSc scholarship from FAPESP. SAN thanks support from FAPESP through a visiting science grant (# 2012/0519-3) which made this collaboration possible. ACM was supported by FAPESP, CAPES, and CNPq. This work was funded by the project CAPES PROCAD and PROTAX, FAPESP (2010/52324-6, 2011/50242-5, 2013/50484-4), and CNPq (562143/2010-6, 563106/2010-7, 477156/2011-8, 458555/2013-4, 458555/2013-4). This publication is a contribution of NP-BioMar, USP. [ST

Groups travel further: pelagic metamorphosis and polyp clustering allow higher dispersal potential in sun coral propagules

We report that planulae produced by Tubastraea coccinea can metamorphose and aggregate in groups of up to eight polyps in the water column, without previous settlement on benthic substrate. We also evaluated the survival of propagules to test whether different levels of aggregation allowed for longer planktonic life and, therefore, higher dispersal potential. Our results show that pelagic polyps live longer than planulae, probably because they can feed and meet the presumably high-energy demands of swimming. Clusters of two or more individuals lived longer than solitary polyps. However, mortality did not differ between small (2–3 polyps) and large (4–8 polyps) clusters, suggesting the existence of an upper limit to cluster size. Most swimming clusters (80 %) remained alive after 6 months, suggesting that pelagic metamorphosis and cluster formation can be a key life-history feature increasing dispersal potential, population connectivity, and the colonization of new habitats in this invasive species.CAPES (Coordenação de de Aperfeiçoamento de Pessoal de Nível Superior)FAPESP (Fundação de Apoio à Pesquisa do Estado de São Paulo)Research Centre for Marine Biodiversity of the University of São Paulo (NP-Biomar/USP

Importância da escala temporal e do tipo de microhabitat em levantamentos de assembleias de hidroides (Cnidaria, Hydrozoa) no canal de São Sebastião (SE Brasil)

Suprimento de propágulos e seu recrutamento modulam a riqueza e a abundância de espécies em comunidades marinhas epifaunais. Estes fatores não estão igualmente distribuídos no tempo e no espaço. A variação temporal no recrutamento pode ser explicada por variações na temperatura, que afeta ciclos anuais de crescimento, reprodução e abundância das espécies. Adicionalmente, a frequência das espécies não é uniforme no tempo e no espaço - muitas são raras e dificilmente detectadas - fazendo com que apenas as mais comuns sejam observadas em grande parte dos estudos de biodiversidade. Além do aspecto temporal, a diversidade pode variar em escalas espaciais locais, nas quais heterogeneidades ambientais se tornam evidentes. Larvas frequentemente selecionam microhabitats para assentamento e as espécies podem ter diferentes taxas de sobrevivência pós-assentamento de acordo com suas respostas ao ambiente. Assim, o momento da coleta dos dados, o tempo de submersão do substrato e o local de coleta podem influenciar estimativas de composição, riqueza e abundância de espécies em comunidades marinhas bentônicas, devendo ser considerados em esforços para compreender a diversidade local. Examinamos a variação temporal no recrutamento de espécies, a diferenciação de microhabitats e o tempo de submersão do substrato como potenciais fontes de variação na riqueza, composição e abundância em assembleias de cnidários bentônicos. Ao longo de dois anos em Ilhabela, no sudeste do Brasil, 30 placas de recrutamento de 12 x 12 cm foram submergidas e retiradas a cada três meses. Placas amarradas duas a duas espaçadas por 2 cm permitiram quantificar o recrutamento em faces abrigadas e expostas. Os dados foram analisados quantificando diferentes aspectos da dinâmica temporal e ocorrência espacial das espécies e por análises multivariadas em PRIMER v6. Encontramos que a estimativa da riqueza em assembleias de cnidários é influenciada pelo momento e tempo de submersão do substrato, basicamente devido ao acúmulo de espécies raras com o aumento do tempo de submersão do substrato e, secundariamente, pela ocorrência de sazonalidade nas espécies. A heterogeneidade de microhabitats pode influenciar, principalmente, a abundância e, em menor grau, a composição de espécies, enquanto a riqueza não é afetada. O tempo de submersão dos substratos também não influenciou a riqueza, mas sim a composição e a abundância, sugerindo mudanças constantes na assembleia em vez do acúmulo de espécies com o tempo. Nossos resultados destacam a importância de se considerar a escala temporal e a heterogeneidade ambiental em levantamentos de assembleias bentônicas e quaisquer derivações de avaliação de diversidade.FAPESPCAPESCNP

Geographical variation of multiplex ecological networks in marine intertidal communities

Understanding the drivers of geographical variation in species distributions, and the resulting community structure, constitutes one of the grandest challenges in ecology. Geographical patterns of species richness and composition have been relatively well studied. Less is known about how the entire set of trophic and non‐trophic ecological interactions, and the complex networks that they create by gluing species together in complex communities, change across geographical extents. Here, we compiled data of species composition and three types of ecological interactions occurring between species in rocky intertidal communities across a large spatial extent (~970 km of shoreline) of central Chile, and analyzed the geographical variability in these multiplex networks (i.e., comprising several interaction types) of ecological interactions. We calculated nine network summary statistics common across interaction types, and additional network attributes specific to each of the different types of interactions. We then investigated potential environmental drivers of this multivariate network organization. These included variation in sea surface temperature and coastal upwelling, the main drivers of productivity in nearshore waters. Our results suggest that structural properties of multiplex ecological networks are affected by local species richness and modulated by factors influencing productivity and environmental predictability. Our results show that non‐trophic negative interactions are more sensitive to spatially structured temporal environmental variation than feeding relationships, with non‐trophic positive interactions being the least labile to it. We also show that environmental effects are partly mediated through changes in species richness and partly through direct influences on species interactions, probably associated to changes in environmental predictability and to bottom‐up nutrient availability. Our findings highlight the need for a comprehensive picture of ecological interactions and their geographical variability if we are to predict potential effects of environmental changes on ecological communities