Guilherme Corte | Universidade Estadual de Campinas (original) (raw)

Papers by Guilherme Corte

Climate change is predicted to lead to more extreme weather events, including changes to storm fr... more Climate change is predicted to lead to more extreme weather events, including changes to storm frequency, intensity and location. Yet the ecological responses to storms are incompletely understood for sandy shorelines, the globe's longest land-ocean interface. Here we document how storms of different magnitude impacted the invertebrate assemblages on a tidal flat in Brazil. We specifically tested the relationships between wave energy and spatial heterogeneity, both for habitat properties (habitat heterogeneity) and fauna (β-diversity), predicting that larger storms redistribute sediments and hence lead to spatially less variable faunal assemblages. The sediment matrix tended to become less heterogeneous across the flat after high-energy wave events, whereas β-diversity increased after storms. This higher β-diversity was primarily driven by species losses. Significantly fewer species at a significantly lower density occurred within days to weeks after storms. Negative density and biomass responses to storm events were most prominent in crustaceans. Invertebrate assemblages appeared to recover within a short time (weeks to months) after storms, highlighting that most species typical of sedimentary shorelines are, to some degree, resilient to short-term changes in wave energy. Given that storm frequency and intensity are predicted to change in the coming decades, identifying properties that determine resilience and recovery of ecosystems constitute a research priority for sedimentary shorelines and beyond.

Evergreen species of temperate regions are dominant in low-nutrient soils. This feature is attrib... more Evergreen species of temperate regions are dominant in low-nutrient soils. This feature is attributed to more efficient mechanisms of nutrient economy. Nevertheless, the cashew (Anacardium occidentale-Anacardiaceae), a deciduous species, is native to regions in Brazil with sandy soil, whilst the annatto (Bixa orellana-Bixaceae), classified as an evergreen species native to tropical America, grows spontaneously in regions with more humid soils. Evergreens contain robust leaves that can resist adverse conditions for longer. The physical aspects of the leaves and mechanisms of nutrient economy between the two species were compared, in order to verify whether the deciduous species had more efficient mechanisms that might explain its occurrence in regions of low soil fertility. The mechanisms of nitrogen economy were also compared for the two species at available concentrations of this nutrient. The following were analysed: (i) leaf life span, (ii) physical leaf characteristics (leaf mass per area, and rupture strain), (iii) nitrogenous compounds (nitrogen, chlorophyll, and protein), (iv) nitrogen conservation mechanisms (nitrogen resorption efficiency, resorption proficiency, and use efficiency), and (v) nitrogen conservation mechanisms under different availability of this mineral. The higher values of leaf mass per area and leaf rupture strain found in A. occidentale were related to its longer leaf life span. A. occidentale showed lower concentrations of nitrogen and protein in the leaves than B. orellana. Under lower nitrogen availability, A. occidentale had higher nitrogen resorption proficiency, nitrogen use efficiency and leaf life span than B. orellana. These characteristics may contribute to the adaptation of this species to sandy soils with low nitrogen content. RESUMO: Perenifólias de clima temperado são dominantes em solos pouco férteis. Essa característica é atribuída a mecanismos mais eficientes de economia de nutrientes. O cajueiro (Anacardium occidentale-Anacardiaceae), uma espécie decídua, é nativo de região do Brasil com solos arenosos, enquanto que o urucuzeiro (Bixa orellana-Bixaceae), uma perenifólia, nativa da América tropical, é espontâneo em regiões com solo mais úmido e fértil. As perenifólias apresentam folhas robustas, adaptadas a resistir a adversidades por mais tempo. Compararam-se aspectos físicos das folhas e mecanismos de economia de nutrientes entre as duas espécies, a fim de verificar se a espécie decídua apresenta mecanismos mais eficientes, que expliquem sua ocorrência em locais pouco férteis. Foram também comparados os mecanismos de economia de nitrogênio sob disponibilidades diferentes deste nutriente. Foram avaliados: (i) longevidade foliar, (ii) características físicas das folhas (massa por área e tensão de ruptura), (iii) concentração de compostos nitrogenados nas folhas (nitrogênio, clorofila e proteínas), (iv) mecanismos de conservação de nitrogênio (eficiência de reaproveitamento, proficiência de reaproveitamento e eficiência do uso), (v) mecanismos de conservação de nitrogênio sob disponibilidades diferentes deste elemento. A maior longevidade foliar de A. occidentale foi relacionada a valores maiores de massa foliar específica e tensão de ruptura foliar. A. occidentale apresentou menores concentrações de nitrogênio e proteínas. Sob menor disponibilidade de nitrogênio A. occidentale apresentou maiores valores de proficiência de reaproveitamento e eficiência do uso de nitrogênio e maior longevidade foliar. Essas características podem ter contribuído para a adaptação dessa espécie a locais com solos arenosos mais pobres em nitrogênio. Palavras-chave: deciduidade foliar, proficiência de reaproveitamento de nitrogênio, eficiência do uso de nitrogênio, tensão de ruptura da folha

Knowledge of the population dynamics and productivity of exploited species is essential to achiev... more Knowledge of the population dynamics and productivity of exploited species is essential to achieve the sustainable development of fisheries, and to ensure sustainable, long-term use of these resources. The venerid clam Anomalocardia brasiliana is harvested as a fishery resource from the French West Indies to Brazil. Yet, the exploitation of this species is not backed by management or regulations based on scientific knowledge. This can result in reduced (or even depleted) A. brasiliana density and biomass. Here, we examined the population dynamics of A. brasiliana over the course of 1 year at Cidade Beach, a sheltered sandy beach located in south-eastern Brazil. Sampling was done monthly from March 2007 to February 2008. The sampled population was predominantly juvenile. Growth and recruitment were continuous, indicating no major fluctuation in limiting factors, such as temperature, salinity and food. Nevertheless, the abundance and the turnover rate (P/B ratio) of A. brasiliana at Cidade were much smaller than the values observed in other areas of occurrence. The mortality was more intense in young individuals, and the peak of individual production occurred in individuals with a 25 mm shell length, suggesting that individuals smaller than this size should not be exploited.

The positive influence of mangrove vegetation on macrobenthic communities has been widely investi... more The positive influence of mangrove vegetation on macrobenthic communities has been widely investigated, but studies mainly focused on epibenthic assemblages. Given the contrasting characteristics between epifauna and infauna, we expected that mangrove vegetation would not exert the same positive effect on infaunal assemblages. To test this hypothesis, we investigated polychaete assemblages in mangrove stands in a tidal flat in Southeast Brazil. Specifically, we focused on (a) whether polychaete assemblages (i.e., density, richness, community, and feeding guild composition) are different inside and outside mangrove stands, and (b) if changes are related to root biomass. Our results showed that mangrove areas have lower polychaete density than that of adjacent sandflats, and polychaete density is negatively related to root biomass. Species richness was not affected by the presence of vegetation, but the number of exclusive species was higher inside the mangrove. Changes in composition of polychaete assemblages were mainly attributable to reductions in species density rather than species replacement. Trophic structure was not influenced by mangrove vegetation, as subsurface-feeders dominated inside and outside mangrove zones. Our results contrast with the richness enhancement found for epibenthic fauna inside mangroves, and highlight that mangrove vegetation does not exert the same influence on epibenthic as that on infaunal assemblages.

The reproductive cycle and parasitism in the clam Anomalocardia brasiliana were studied in two di... more The reproductive cycle and parasitism in the clam Anomalocardia brasiliana were studied in two different areas, an intermediate beach (Cidade) and a tidal flat (Araçá), in Southeast Brazil. Four gametogenic stages were described for males and females in both areas. Mature and spawning individuals were present throughout the period of study at Cidade and Araçá; however, major temporal differences were recorded between sites. Whereas only a few individuals in the resting stage were recorded at Cidade throughout the study period, resting stage individuals were frequent at Araçá. Moreover, a shorter period of gametogenesis was observed at Araçá than at Cidade. Oocyte number was the most effective parameter to differentiate gametogenic stages. An unidentified digenetic trematode was the only parasite infecting A. brasiliana at the study sites, and caused castration of all hosts. Parasite prevalence (proportion of infected hosts) was similar and low (ca 7.5%) at Cidade and Araçá and therefore is not expected to compromise the reproductive output of these populations. Comparison with data from previous studies suggests a latitudinal pattern for the reproductive biology of A. brasiliana, with resting stages occurring only at two high-latitude sites; however, no evidence was found for a latitudinal pattern of trematode prevalence in this species.

Tagelus plebeius (Lightfoot, 1786) is a stout razor clam that is economically exploited in severa... more Tagelus plebeius (Lightfoot, 1786) is a stout razor clam that is economically exploited in several countries, including several local fisheries along the Brazilian coast. Despite its wide distribution and economic importance, there are few studies that have examined the population biology of this species. This study aimed to improve the current knowledge about the biology of T. plebeius by investigating its growth and mortality on a subtropical sandy beach in Southeast Brazil over a 1-year period. In addition, the reproduction of T. plebeius was analyzed through qualitative and quantitative histological analyses during the last 7 months of the study. The parameters of the von Bertalanffy growth function were estimated to be L ? = 74.14 mm, K = 0.52 year-1 , C = 0.47, and WP = 0.94. The instantaneous mortality rate (Z) was 2.16 year-1 , and the life span was 2.58 years. We confirmed variations (H = 651.35; P \ 0.05) in the shell length over the months of the study, and the recruitment was higher—but still low—in summer. Four cohorts were observed in the distribution of shell length frequencies. The sex ratio of the population was 1:1 during the study period, and a synchronism in gonadal development and spawning was found between males and females. The high mortality (Z) and low recruitment rates can be interpreted as reflecting that the population of T. plebeius is under a low restoration process and could be an indication that this species has an endangered status in the study area.

Comunidades associadas às macroalgas são conhecidas por abrigar uma fauna abundante e diversifica... more Comunidades associadas às macroalgas são conhecidas por abrigar uma fauna abundante e diversificada. Apesar da importância ecológica desse ambiente, trabalhos com macroalgas de costões rochosos são relativamente escassos e realizados principalmente com espécies estruturalmente mais complexas. O objetivo deste trabalho foi analisar a fauna de crustáceos associada à macroalga verde Ulva spp., presente em costões rochosos da praia das Cigarras e da baía do Araçá, ambas no município de São Sebastião, Litoral Norte do Estado de São Paulo. Em cada área, nove amostras de Ulva spp. foram coletadas. Na baía do
Araçá, foi possível distinguir três faixas de amostragem, tendo sido coletadas três amostras em cada faixa (médio-litoral superior; médio-litoral inferior e franja do infralitoral). Anfípodes e isópodes estiveram presentes em maior número nas duas áreas amostradas, entretanto somente na baía do Araçá o anfípode Parhyale hawaiensis foi observado em grande quantidade. A densidade média dos crustáceos associados à Ulva spp. foi cerca de quatro vezes maior na baía do Araçá em relação à praia das Cigarras. Não houve diferença significativa quanto ao índice de diversidade de Shannon-Wiener entre as praias ou entre as faixas de costão do Araçá. Entre os fatores que podem determinar a maior densidade de crustáceos associados à Ulva spp. no Araçá, podem ser destacados o menor hidrodinamismo nessa área e a ausência de outras espécies de algas que possam servir como substrato biológico para a epibiota.

The Habitat Harshness Hypothesis (HHH) predicts that populations inhabiting the intertidal area o... more The Habitat Harshness Hypothesis (HHH) predicts that populations inhabiting the intertidal area of a dissipative beach should produce more gametes and have a longer reproductive cycle than those inhabiting an intermediate or reflective beach. This hypothesis was proposed for the exposed morpho-dynamic continuum between the reflective and dissipative states; however, no attempt has been made thus far to verify whether the HHH is valid for tidal flats. In this study, we analysed the reproductive cycle of Anomalocardia brasiliana in an intermediate beach and in a tidal flat and compared the results to determine whether the reproductive cycles of A. brasiliana were in agreement with the predictions of the HHH and to examine the possibility of extending this hypothesis to tidal flats. A continuous spawning season and synchrony between sexes were observed at both sites, although the reproductive effort was higher in the intermediate beach. The results of this first attempt did not support the extension of the HHH to tidal flats. It is possible that hypotheses that take into account only physical variables may not be the most adequate for describing environments with such a high species richness and high abundance as tidal flats. Nevertheless, other studies are necessary to confidently expand or refute the HHH with regard to tidal flats, and this topic should be considered as a priority in future investigations in sandy beach ecology.

Understanding how species respond to the environment in terms of population attributes (e.g. abun... more Understanding how species respond to the environment in terms of population attributes (e.g. abundance, growth, mortality, fecundity, and productivity) is essential to protect ecologically and economically important species. Nevertheless, responses of macrobenthic populations to environmental features are overlooked due to the need of consecutive samplings and time-consuming measurements. We examined the population dynamics of the filter-feeding bivalve Anomalocardia brasiliana on a tidal flat over the course of one year to investigate the hypothesis that, as accepted for macrobenthic communities, populations inhabiting environments with low hydrodynamic conditions such as tidal flat should have higher attributes than populations inhabiting more energetic habitats (i.e. areas more influenced by wave energy such as reflective and intermediate beaches). This would be expected because the harsh conditions of more energetic habitats force organisms to divert more energy towards maintenance, resulting in lower population attributes.We found that A. brasiliana showed moderate growth and secondary production at the study area. Moreover the recruitment period was restricted to a few months. A comparison with previous studies showed that, contrary to expected, A. brasiliana populations from areas with low hydrodynamic conditions have lower abundance, growth, recruitment and turnover rate. It is likely that morphodynamic characteristics recorded in these environments, such as larger periods of air exposure and lower water circulation, may affect food conditions for filter-feeding species and increase competition. In addition, these characteristics may negatively affect macrobenthic species by enhancing eutrophication processes and anoxia. Overall, our results suggest that models accepted and applied at the macrobenthic community level might not be directly extended to A. brasiliana populations