Variation in the body growth parameters of the ghost crab Ocypode quadrata from morphodynamically distinct sandy beaches

Os padrões de distribuição da macrofauna de praias arenosas têm sido amplamente investigados, mostrando que o entre-marés de praias dissipativas tende a concentrar maiores valores de riqueza e biomassa, bem como indivíduos de maior sucesso reprodutivo e tamanho, do que praias reflexivas. Para crustáceos do supralitoral essa tendência é em geral oposta. Para o guaruçá, Ocypode quadrata, frequentemente o grupo mais conspícuo desses ambientes, são raras as investigações de dinâmica populacional e respostas a diferentes morfologias praiais. Aqui, a variação de tamanho e o crescimento corpóreo foram avaliados ao longo de um ano através do método indireto em três praias com reduzido impacto antrópico no Litoral Norte de São Paulo. Estas foram escolhidas de froma a representarem três tipos básicos de morfodinâmica: dissipativa (Costa), intermediária (Félix) e reflectiva (Puruba). Em cada praia, cinco transectos de 2m de largura foram aleatorizados mensalmente, e avaliados da primeira à última ocorrência de tocas. O ajuste do modelo de crescimento de von Bertalanffy foi comparada entre as áreas. Para as três praias uma moda principal, devido à entrada de juvenis (mm), foi identificada em agosto/setembro. Esses indivíduos atingiram no verão seguinte um tamanho correspondente à moda principal do verão anterior, e dentro daquela que foi dominante no período como um todo. Especificamente, os parâmetros de crescimento foram: Costa (dissipativa) L∞ = 46,36 milímetros, K = 0,90 ano-1 e t0 = -0,19; Félix (intermediária) L∞ = 57,95 milímetros, K = 0,87 ano-1 e t0 = -0,12; Puruba (reflexiva) L∞ = 53,01 milímetros, K = 1,11 ano-1 e t0 = -0,07. Esses ajustes foram iguais estatisticamente entre Puruba e Felix, sendo ambos distintos da praia do Costa. Os índices de crescimento, phi-prima, variaram de 3,29 (Costa) a 3,49 (Puruba), enquanto na praia Félix esse valor foi 3,46, indicando homogeneidade deste parâmetro entre as praias, mas reforçando a maior semelhança a praia intermediária e reflexiva.Investigations of patterns of distribution of sandy beach macrofauna show that dissipative beaches tend to concentrate higher richness and biomass at the intertidal zone, as well as better fitness and larger sizes of a species, than reflective beaches. For supralittoral crustaceans, these trends are inverted, as predicted by the habitat safety hypothesis (HSH). For ghost-crabs, however, higher population abundance has been observed on dissipative beaches, but their life-history traits and the response to different beach morphologies were not well defined. Here, variation in crab size and growth was evaluated over a one year period using indirect measures from three low-impact beaches on the northern coast of São Paulo State, southeastern Brazil. These beaches represent the three basic types of morphodynamics: dissipative (Costa beach), intermediate (Felix beach) and reflective (Puruba beach). At each site, five 2m wide transects were randomly selected each month, and assessed across the crabs' entire area of occurrence. The fit of the von Bertalanffy body growth model was compared among sites. For all three beaches, a main mode due to the settlement of juveniles (mm) was identified in August and September. In the following summer, according to growth estimates, the settlement group would be approximately the same size as the main mode (mm) that was recorded during the previous summer. Specifically, the growth parameters estimated were: Costa (dissipative) L∞= 46.36mm, K= 0.90year-1 and t0= -0.19; Félix (intermediate) L∞= 57.95mm, K= 0.87year-1 and t0= -0.12; Puruba (reflective) L∞= 53.01mm, K= 1.11year-1 and t0= -0.07. The body growth adjustments were similar between Puruba and Felix, but distinct from Costa. Growth performance indexes ranged from 3.29 (Costa) to 3.46 (Félix) and 3.49 (Puruba), indicating both the homogeneity of this parameter among distinct beaches and close agreement between the intermediate and reflective beaches. This study suggests that variations in the development of ghost crabs concur with those observed for other supralittoral, crustaceans and the habitat safety hypothesis, with higher individual fitness for reflective beaches

Temporal variation in Sargassum Biomass, Hypnea epiphytism and associated fauna

Studies were carried out to investigate the temporal variation in Sargassum biomass, Hypnea epiphytism and associated fauna. There was a marked variation in the biomass of Sargassum and Hypnea among various sampling periods. Low values for Sargassum were recorded in August and November, while the lower value for Hypnea biomass was recorded in August. An inverse relationship was found between Sargassum biomass and the intensity of Hypnea epiphytism. The density of the total fauna associated to Sargassum showed a marked reduction in May. This variation was influenced by the variation patterns of the dominant faunistic groups (Gastropoda, Gammaridea, Isopoda and Caridea). Significant positive relationships were found between the biomass of Sargassum and Sargassum+Hypnea with the total density of all faunistic groups (per macroalgae biomass unit). However, the influence of Hypnea epiphytism on the phytal organisms was not evidenced.Sargassum cymosum é uma alga muito freqüente e abundante no sudeste do Brasil a qual apresenta uma fauna associada muito diversificada e freqüentemente epifitada pela alga vermelha Hypnea musciformis. Foram realizadas quatro amostragens na Praia do Lamberto, litoral norte do Estado de São Paulo, para observar a variação temporal da biomassa de Sargassum, do epifitismo de Hypnea e da fauna associada. Observou-se uma marcada variação da biomassa de Sargassum e Hypnea entre os períodos de amostragem. Os menores valores para Sargassum foram obtidos em agosto e novembro, enquanto o menor valor para Hypnea foi obtido em agosto. Relação inversa foi observada entre a biomassa de Sargassum e o epifitismo de Hypnea. A densidade da fauna total associada a Sargassum também mostrou variação significativa entre os períodos de amostragem, com marcada redução em maio. Este padrão foi influenciado pela variação dos grupos taxonômicos dominantes (Gastropoda, Gammaridea, Isopoda e Caridea). Observou-se uma forte relação positiva entre a biomassa of Sargassum e Sargassum+Hypnea com a abundância de todos os grupos taxonômicos. Contudo, não ficou evidenciada a influência do epifitismo de Hypnea sobre os organismos do fital.665671Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Population biology of the hermit crab Petrochirus diogenes (Linnaeus) (Crustacea, Decapoda) in Southern Brazil

The aim of this study was to provide information on the biology of a subtropical population ofthe hermit crab Petrochirus diogenes focusing size structure, sex ratio, reproductive period and morphometric relationships. Monthly samples were done between January and December 1995 at Armação of Itapocoroy, Penha, southern Brazil, using two over-trawls in depths from 6.0 to 10.0 m. A total of 126 individuais were collected. Overall sex ratio did not differ from 1:1. When the sex ratio was analyzed for each size class, it was skewed for females in the smallest size classes while males outnumbered females in the largest ones. The mean size (cephalothoracic length) of P. diogenes was 30.61 ± 12.52 mm and the size structure of this population was skewed to the right. Males were on average larger and heavier than both ovigerous and non-ovigerous females, which, in turn, showed similar sizes and weights. The ovigerous females represented 61% ofall females and occurred from January to April and in September and December. The relationship of cephalothoracic length and both cephalothoracic width and crab weight were isometric. Both crab size and weight showed a negative allometry with shell weight, indicating that larger/heavier crabs use proportionally lighter shells than small-sized ones.1043105

Annual variation of the malacofauna on two intertidal sandy substrates with rock fragments in southeastern Brazil

The temporal variation in molluscan communities was studied in two intertidal substrates composed of sand and rock fragments <300 mm) in São Sebastião Channel, Brazil. Samples were taken between August 1995 and July 1996 in São Francisco (mainland) and Engenho d'Água (São Sebastião Island) beaches. A pronounced decrease in abundance and diversity of molluscs was associated with changes in the structure of the environment, caused by sea storms in the beginning of the summer (December), and by the increase of waste water discharge in this same period. Areas not subjected to such events showed no evident modifications in mollusc fauna structure during the sampling period, and the small oscillations observed were attributed to population recruitment. Both natural and human factors may be acting together in determining the community organization in these environments, as is also in typical sandy beaches.Estudou-se a variação anual da comunidade de moluscos em dois ambientes entremarés constituídos por areia e fragmentos rochosos <300 mm) no Canal de São Sebastião, Brasil. As amostras foram obtidas mensalmente entre agosto de 1995 e julho de 1996 nas praias São Francisco (continente) e Engenho d'Água (Ilha de São Sebastião). Uma marcante redução na abundância e diversidade foi associada às mudanças estruturais do ambiente, causada por ressacas do mar no início do verão (dezembro), e ao aumento no fluxo de esgotos domésticos neste período. Em áreas onde estes eventos não foram evidentes, não houve grande alteração na composição faunística, e as pequenas oscilações foram atribuídas ao recrutamento de populações numericamente importantes. Ambos os fatores naturais e antrópicos podem estar atuando em conjunto para determinar a organização da comunidade nestes ambientes, tal como ocorre em praias arenosas típicas.141150Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Subjective resource value and shell abandoning behavior in hermit crabs

Understanding the factors thatmotivate animals to hold or abandon a valuable resource is a central goal of behavioral ecology, the study of which will grow more important in the face of increasingly frequent extreme events. We compared the shell-abandoning behavior of the sympatric hermit crabs Clibanarius antillensis and Pagurus criniticornis in response to simulated burial and entrapment by rocks and other debris.While these hazards are relatively common in dynamic intertidal habitats, the frequency and severity of such disturbance are increasing due to human activity. While both species exhibited shell-abandoning behavior in response to experimental burial, it was far more prevalent for the soft-bottom dwelling species P. criniticornis (90%) when compared to the rocky bottom inhabitant C. antillensis (55%). Simulated entrapment experiments highlighted further differences in species response, with the decision to abandon domicile shells again far more common for P. criniticornis (80%) than it was for C. antillensis (10%). Given the tendency for P. criniticornis to abandon its shell, we subsequently focused on this species to test specific hypothesis about subjective resource value in hermit crabs. There was no difference in the tendency for this species to abandon optimal or sub-optimal (poorly-fitting) shells when faced with the immediate and potentially fatal risk of burial. This contrasted the response seen under conditions of entrapment, whereby individuals inhabiting sub-optimal shells abandoned them more rapidly and in greater numbers than those inhabiting optimal shells. Combining these two outcomes, we suggest that hermit crabs subjectively assess shell-value and respond according to the nature of the disturbance and its associated risks (i.e., high-value shells are abandoned in minutes under conditions of burial; but are held for hours under the less severe conditions of entrapment). In effect, the results show that extrinsic environmental cues can be just as important to decision making processes as those intrinsic cues that govern an animal's physiological condition. The contrasting behavior of the two hermit crabs to the movement of mud and other debris may lead to a higher survivorship of P. criniticornis than C. antillensis where activities such as dredging and harbor construction are intensifying along developing coastlines

First record of the non-indigenous portunid crab Charybdis variegata from the western Atlantic coast

Biological invasions are a present and growing environmental problem because non-indigenous organisms may affect the structure and functioning of native communities. In the marine environment there are records of invasive species in almost all phyla, including crustaceans, and the portunid crabs of the genus Charybdis are among the most widespread invasive groups. We report the first record of Charybdis variegata (Fabricius, 1798) from the western Atlantic coast. This species was collected on an intertidal rocky shore near Santos Harbor, São Paulo state, Brazil. Of 311 portunid crabs sampled, 309 individuals belonged to the non-indigenous Charybdis hellerii (A. Milne Edwards, 1867), one was a native Cronius ruber (Lamarck, 1818), and one was identified as the non-indigenous Charybdis variegata. This individual was a juvenile female measuring 27.5 mm in carapace width. The taxonomic traits used for species identification, as well as a morphological comparison between C. hellerii and C. variegata are presented. The introduction route and establishment status of this species are also discussed.FAPESP - 2005/04707-5FAPESP - Biota - 2010/50188-8FAPESP - 2006/57007-3CNPq - FJZ 308215/2010-9CNPq - AT 301240/2006-0CNPq - TTW PiBIC 138732/2011-

Traditional ecological knowledge supports ecosystem-based management in disturbed coastal marine social-ecological systems

A growing number of studies suggest a participatory ecosystem approach to support decision-making toward resilience and sustainability in social-ecological systems. Social-ecological resilience (SER) principles and practices are recommended to manage natural crises. However, it is necessary to broaden our understanding of SER on human-induced disturbances driven by economic development projects. In this paper we present the social-ecological system of Araçá Bay (Brazil), a small-scale fishery community that has experienced successive disturbances due to development projects since the 1930s. There was a lack of studies about the impacts of development projects in this bay. As part of a major project that aimed to build an ecosystem-based management plan for Araçá Bay through a participatory planning process, we focused on investigating fishers’ traditional ecological knowledge (TEK) to understand Araçá Bay’s small-scale fisheries social-ecological system. The objectives were to: (1) investigate fishers’ TEK regarding management practices and linked social mechanisms, human-induced disturbances and their consequences for the social-ecological system, ecosystem goods and services, and future threats; and (2) provide information based on TEK to the participatory planning process and analyze its contribution to Araçá Bay’s ecosystem-based management plan. Combined methods were used during 3 years of intense research-action (2014–2017): in-depth ethno-oceanographic interviews with expert fishers; monitoring Araçá Bay participatory meetings; and participant observation. Genuine local practices and social mechanisms from traditional culture were recorded, as well as TEK about 57 target fish species and methods to protect habitats and natural resources. Fishers also reported ecosystem disturbances and recovery processes. TEK was codified through SWOT analysis to assist the participatory planning process. Ecosystem services and threats based on TEK were brought to the participatory process, acknowledged by the participants, and incorporated into the management plan. TEK analysis proved to be an important methodology to provide historical environmental data regarding the impacts of development projects and support planning in disturbed ecosystems. In order to support coastal marine ecosystem-based management strategies toward SER and sustainability, researchers and practitioners should consider traditional territories in planning, recognize local practices and social mechanisms, and consider TEK on ecosystem goods and services and on historical human-induced disturbances