Correspondence analysis of raw data

Correspondence analysis has found extensive use in ecology, archeology, linguisticsand the social sciences as a method for visualizing the patterns of association in a table offrequencies or nonnegative ratio-scale data. Inherent to the method is the expression of the datain each row or each column relative to their respective totals, and it is these sets of relativevalues (called profiles) that are visualized. This relativization of the data makes perfect sensewhen the margins of the table represent samples from sub-populations of inherently differentsizes. But in some ecological applications sampling is performed on equal areas or equalvolumes so that the absolute levels of the observed occurrences may be of relevance, in whichcase relativization may not be required. In this paper we define the correspondence analysis ofthe raw unrelativized data and discuss its properties, comparing this new method to regularcorrespondence analysis and to a related variant of non-symmetric correspondence analysis.

Composition of the Ant Fauna (Hymenoptera: Formicidae) in Public Squares in Southern Brazil

The composition of the ant fauna was examined in public squares of three municipalities that compose the hydrographic basin of the Upper Tiete River: Biritiba Mirim, Salesopolis, and Mogi das Cruzes. Richness, frequency of occurrence, similarity, and influence of seasons on the species composition were examined. The method was standardized as sampling units consisted of a set of three baits arranged in a triangle with vertices two meters apart. Sardines in oil were used as attractant. A total of 86 species was collected. Myrmicinae and Pheidole were the richest subfamily and genus, respectively. Eighty species were collected in Mogi das Cruzes, 49 in Salesopolis, and 45 in Biritiba Mirim, with 34 species common to the three areas. The ordination analysis (NMDS) revealed the presence of two distinct communities: one in Mogi das Cruzes and another in Biritiba Mirim-Salesopolis. These data were supported by the dendogram based on the Bray-Curtis dissimilarity index. This result might be associated with the distinct geographic and demographic characteristics of the areas. Regarding seasonality, the composition of the fauna of Mogi das Cruzes is independent of the season of the year, unlike the observed in Biritiba Mirim and Salesopolis.

Metacommunity Dynamics Of Benthic Macroinvertebrates In A Large River

Metacommunity ecology focuses on the interaction between local communities and is inherently linked to dispersal as a result. Within this framework, communities are structured by a combination of in-site responses to the immediate environment (species sorting), stochasticity (patch dynamics), and connections to other communities via distance between communities and dispersal (neutrality), and source-sink dynamics (mass effects; see Chapter 1 for a detailed description of metacommunity theory, the study site, and macroinvertebrate communities found). In Chapter 2 I describe spatial scale of study and dispersal ability as both have the ability to influence the degree to which communities interact. However, little is known about how these factors influence the importance of all metacommunity dynamics. I compared dispersal mode of immature aquatic insects and dispersal ability of winged adults across multiple spatial scales in a large river. The strongest drivers of river communities were patch dynamics, followed by species sorting, then neutrality. Active dispersers during aquatic lifestages on average exhibited lower patch dynamics, higher species sorting, and significant mass effects compared to passive dispersers. Active and strong dispersers also had a scale-independent influence of neutrality, while neutrality was stronger at broader spatial scale for passive and weak dispersers. These results indicate as dispersal ability increases patch dynamics decreases, species sorting increases, and neutrality should decrease. The perceived influence of neutrality may also be dependent on spatial scale and dispersal ability. In Chapter 3 I describe how river benthic macroinvertebrate communities may influence tributary invertebrate communities via adult flight and tributaries may influence mainstem communities via immature drift. This relationship may also depend on relative mainstem and tributary size, as well as abiotic tributary influence on mainstem habitat. To investigate the interaction between a larger river and tributary I sampled mainstem benthic invertebrate communities and quantified habitat of a 7th order river (West Branch Susquehanna River) above and below a 5th order tributary confluence, as well as 0.95-3.2 km upstream in the tributary. Non-metric multidimensional scaling showed similar patterns of clustering between sampling locations for both habitat characteristics and invertebrate communities. In addition, mainstem river communities and habitat directly downstream of the tributary confluence cluster tightly together, intermediate between tributary and mid-channel river samples. In Bray-Curtis dissimilarity comparisons between tributary and mainstem river communities the furthest upstream tributary communities were least similar to river communities. Middle tributary samples were also closest by Euclidean distance to the upstream mainstem riffle and exhibited higher similarity to mid-channel samples than the furthest downstream tributary communities. My results indicate river and tributary benthic invertebrate communities may interact and likely result in direct and indirect mass effects of a tributary on the downstream mainstem community by invertebrate drift and habitat restructuring via material delivery from the tributary. I also showed likely direct effects of adult dispersal from the river and oviposition in proximal tributary locations where Euclidian, rather than river, distance may be more important in determining river-tributary interactions.

Tributary and Mainstem Benthic Macroinvertebrate Communities Linked By Direct Dispersal and Indirect Habitat Alteration

Benthic communities in tributary-mainstem networks might interact via downstream drift of invertebrates or material from tributaries and adult dispersal from the mainstem. Depending on the strength of these interactions, mainstem downstream communities are expected to be more similar to tributary communities due to drift or habitat alteration. Communities not connected by flow are expected to be similar due to adult dispersal but decreasing in similarity with distance from the mainstem. We investigated interactions between invertebrate communities of a 7th order river and 5th order tributary by comparing benthic community structure in the river upstream and downstream of the tributary confluence and upstream in the tributary. Non-metric multidimensional scaling showed invertebrate communities and habitat traits from river locations directly downstream of the tributary clustered tightly, intermediate between tributary and mid-channel river locations. In addition, Bray-Curtis dissimilarity increased between the mainstem and tributary with distance upstream in the tributary. Our results indicate that similarities between mainstem and tributary communities are potentially caused by direct mass effects from tributary to downstream mainstem communities by invertebrate drift and indirect mass effects by habitat restructuring via material delivery from the tributary, as well as potential effects of adult dispersal from the river on proximal tributary communities.

Investigating bias in recreational fishing surveys: Fishers listed in public telephone directories fish similarly to their unlisted counterparts

Several recent offsite recreational fishing surveys have used public landline telephone directories as a sampling frame. Sampling biases inherent in this method are recognised, but are assumed to be corrected through demographic data expansion. However, the rising prevalence of mobile-only households has potentially increased these biases by skewing raw samples towards households that maintain relatively high levels of coverage in telephone directories. For biases to be corrected through demographic expansion, both the fishing participation rate and fishing activity must be similar among listed and unlisted fishers within each demographic group. In this study, we tested for a difference in the fishing activity of listed and unlisted fishers within demographic groups by comparing their avidity (number of fishing trips per year), as well as the platform used (boat or shore) and species targeted on their most recent fishing trip. 3062 recreational fishers were interviewed at 34 tackle stores across 12 residential regions of Queensland, Australia. For each fisher, data collected included their fishing avidity, the platform used and species targeted on their most recent trip, their gender, age, residential region, and whether their household had a listed telephone number. Although the most avid fishers were younger and less likely to have a listed phone number, cumulative link models revealed that avidity was not affected by an interaction of phone listing status, age group and residential region (p > 0.05). Likewise, binomial generalized linear models revealed that there was no interaction between phone listing, age group and avidity acting on platform (p > 0.05), and platform was not affected by an interaction of phone listing status, age group, and residential region (p > 0.05). Ordination of target species using Bray-Curtis dissimilarity indices found a significant but irrelevant difference (i.e. small effect size) between listed and unlisted fishers (ANOSIM R < 0.05, p < 0.05). These results suggest that, at this time, the fishing activity of listed and unlisted fishers in Queensland is similar within demographic groups. Future research seeking to validate the assumptions of recreational fishing telephone surveys should investigate fishing participation rates of listed and unlisted fishers within demographic groups.

A estrutura trófica da ictiofauna de riachos reflete a estrutura física do habitat?

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comparación de las macroalgas epizóicas de la madreperla Pinctada mazatlanica (Hanley 1856) con las de fondos rocosos en la bahía de La Paz, Baja California Sur, México

El presente estudio describe la comunidad de macroalgas epizóicas de Pinctada mazatlanica y la compara con la del substrato rocoso. Colectamos un total de 36 muestras de la comunidad de macroalgas, 18 muestras sobre ostras y otras tantas sobre substrato rocoso en la Península San Juan Nepomuceno, bahía de La Paz, México. Las algas fueron colectadas mediante buceo SCUBA raspando las distintas superficies (25 cm2 de substrato rocoso). El tamaño de muestra fue ajustado por curva de acumulación de especies y expresado con un modelo polinomial. Comparamos las comunidades de algas con análisis multivariantes de similitud basados en el índice de Bray-Curtis, entre substratos, diferentes alturas de ostras perleras y profundidades. Encontramos 27 especies de algas epizóicas (15.4% Clorophyta, 3.8% Phaeophyta y 80.8% Rhodophyta) con una disimilitud de 71.16% con respecto al substrato rocoso. El dendrograma mostró tres agrupaciones de macroalgas en P. mazatlanica. El primero caracterizado por Chondria, Jania, Herposiphonia tenella y Gracilaria. El segundo compuesto por Jania, Polysiphonia acuminata, P. decusata y Spyridia filamentosa. El tercero constituido por Polysiphonia sp., Jania, Herposiphonia tenella, Ceramium canouii y Amphiroa sp. Estas agrupaciones y los talos filamentosos de las algas epizóicas corresponden a estados iniciales de sucesión.

Ocorrência e ecologia trófica de quatro espécies de Astyanax (Characidae) em diferentes rios da bacia do rio Tibagi, Paraná, Brasil

Na bacia do rio Tibagi, trechos dos rios Fortaleza, Iapó e Tibagi foram amostrados mensalmente, de maio de 2001 a abril de 2002, com tarrafas e redes de espera de diferentes malhagens. Foram capturados indivíduos de quatro espécies de Astyanax. Para conhecer como essas espécies utilizam o hábitat desses rios, foi calculada a constância, e as freqüências em número de exemplares foram comparadas pela análise de similaridade Bray-Curtis. A composição percentual dos alimentos consumidos foi ordenada usando-se a Análise de Componentes Principais (ACP). As proporções dos recursos alimentares foram avaliadas e classificadas quanto à natureza (animal ou material vegetal) e origem (alóctone e autóctone). A constância e a baixa similaridade na abundância revelaram que as espécies têm preferências quanto ao porte do rio ou por determinado hábitat. Astyanax altiparanae Garutti & Britski, 2000 e A. fasciatus (Cuvier, 1819) ocorreram nos de maior porte, mas foram constantes somente no rio Tibagi. Astyanax eigenmanniorum (Cope, 1894) ocorreu em todos os rios, mas prefere hábitats próximos às desembocaduras de afluentes de grandes rios. Astyanax scabripinnis (Jenyns, 1842) esteve restrita ao Fortaleza, o rio de menor porte, subafluente do rio Tibagi. O número de itens alimentares consumidos variou de 11 a 23. Entre os alimentos principais, três itens foram comuns para as quatro espécies: restos de plantas (folhas e sementes de plantas terrestres), restos de insetos (de diferentes origens e não identificados) e plantas aquáticas. Os vegetais e os insetos foram os principais alimentos para todas as espécies. A maior distinção na composição da dieta foi constatada para A. eigenmaniorum, devido à sua habilidade em explorar as plantas aquáticas, presentes em abundância, consumidas junto com carvão/sedimento, que estavam nas margens rochosas do rio Iapó. A similaridade quanto à origem e ao tipo de alimento consumido pelas quatro espécies e as diferenças em termos de hábitat ocupado podem explicar por que apenas uma delas se mantém em abundância e constância em cada trecho estudado.

Dinâmica trófica de Plagioscion squamosissimus (Perciformes, Sciaenidae) em trechos de influência da represa Capivara (rios Paranapanema e Tibagi)

Plagioscion squamosissimus (Heckel, 1840) foi estudada em cinco trechos de influência da represa Capivara nos rios Paranapanema e Tibagi. As amostragens foram realizadas em dois períodos, 1992/1993 e 1994/1995, em coletas mensais, e sazonalmente no período 2001/2002. As capturas foram efetivadas com redes de espera simples com malhas entre 2 a 12 cm. Foram analisados 993 exemplares. Os itens alimentares identificados foram agrupados em categorias e analisados pelo método da composição percentual. A composição da dieta foi comparada entre os períodos de amostragens e entre trechos, pela análise de similaridade usando o coeficiente de Bray-Curtis. Os resultados indicaram que em todos os períodos e em todos os trechos houve uniformidade no consumo dos tipos de itens alimentares. Os itens encontrados foram agrupados em seis categorias: peixes, camarão, Odonata, Ephemeroptera, outros grupos de insetos e outros (material vegetal, detritos e organismos, raramente encontrados). Em todos os trechos e em todas as épocas analisadas, P. squamosissimus se manteve como carnívora, e no período 2001/2002 o item camarão (Macrobrachium amazonicum) foi o de maior participação em sua dieta. Concomitante com o fato de a corvina trocar de alimento substituindo peixes por camarão, mudou o comportamento quanto à freqüência na tomada de alimento e na variedade de tipos de itens consumidos. Quando P. squamosissimus utiliza camarão, maior número de indivíduos são encontrados nos estômagos, na maioria dos casos com apenas este tipo de item.

Is response to fire influenced by dietary specialization and mobility? A comparative study with multiple animal assemblages

Fire is a major agent involved in landscape transformation and an indirect cause of changes in species composition. Responses to fire may vary greatly depending on life histories and functional traits of species. We have examined the taxonomic and functional responses to fire of eight taxonomic animal groups displaying a gradient of dietary and mobility patterns: Gastropoda, Heteroptera, Formicidae, Coleoptera, Araneae, Orthoptera, Reptilia and Aves. The fieldwork was conducted in a Mediterranean protected area on 3 sites (one unburnt and two burnt with different postfire management practices) with five replicates per site. We collected information from 4606 specimens from 274 animal species. Similarity in species composition and abundance between areas was measured by the Bray-Curtis index and ANOSIM, and comparisons between animal and plant responses by Mantel tests. We analyze whether groups with the highest percentage of omnivorous species, these species being more generalist in their dietary habits, show weak responses to fire (i.e. more similarity between burnt and unburnt areas), and independent responses to changes in vegetation. We also explore how mobility, i.e. dispersal ability, influences responses to fire. Our results demonstrate that differences in species composition and abundance between burnt and unburnt areas differed among groups. We found a tendency towards presenting lower differences between areas for groups with higher percentages of omnivorous species. Moreover, taxa with a higher percentage of omnivorous species had significantly more independent responses of changes in vegetation. High- (e.g. Aves) and low-mobility (e.g. Gastropoda) groups had the strongest responses to fire (higher R scores of the ANOSIM); however, we failed to find a significant general pattern with all the groups according to their mobility. Our results partially support the idea that functional traits underlie the response of organisms to environmental changes caused by fire.

Efeito de queimadas sobre a estrutura e composição da comunidade vegetal lenhosa do cerrado sentido restrito em Caldas Novas, GO

Considerando que o regime de queima é um dos principais fatores que alteram a estrutura e composição de espécies de uma comunidade vegetal, este trabalho teve como objetivo analisar o efeito do fogo na composição florística e estrutura da vegetação lenhosa de Cerrado sentido restrito no Parque Estadual da Serra de Caldas Novas (PESCAN), Goiás, submetida a diferentes regimes de queima. Foram utilizadas duas áreas de Cerrado sentido restrito: uma delas submetida ao fogo em 2002 e 2006 e outra sem a passagem do fogo nessas duas épocas. Em cada área foram estabelecidas 25 parcelas de 20 x 20 m, sendo incluídas no estudo todas as árvores (C30>15 cm). As duas áreas estudadas apresentaram composição florística similar, evidenciada pelo Coeficiente de Sorensen, o qual encontrou 84% de similaridade na composição florística entre as áreas. Entretanto, a estrutura da vegetação apresentou diferenças relevantes, evidenciada pelo Indice de Similaridade de Bray Curtis, o qual obteve valor de 0,67, que foi refletido por mudanças na estrutura das comunidades estudadas. A área queimada apresentou menor número de indivíduos, de espécies, menor valor de área basal e, por conseguinte, do Índice de Diversidade de Shannon (H') e Equabilidade (J'). Nesse sentido, provavelmente a frequência das queimadas ocorridas na área não foram suficientes para evidenciar o efeito do fogo no processo de alteração na composição das espécies lenhosas. Entretanto, o fogo exerceu papel relevante na modificação da estrutura da vegetação.

Species diversity and community structure of ichthyofauna in the seagrass ecosystem of Minicoy Atoll, Lakshadweep, India

Present study consists the species diversity, abundance and community structure of ichthyofauna in the seagrass meadow of Minicoy Atoll, Lakshadweep Islands. Two hundred and three species of fishes were recorded during the study, from four stations in the Atoll. They belonged to 2 classes, 11orders, 43 families and 93 genera. Six species belonged to the class Chondreichthyes and 197 species to Osteichthyes. Family Pomacentridae showed maximum abundance of species (22%). Station I, having close proximity to the coral reefs, observed the maximum number of families (37) and species (129) and that with minimum number was in station II (23 families and 52 species). Bray-Curtis similarity plot showed a similarity range of 22 to 52%, seasonally. Station I showed highest Shannon-Wiener diversity index (H’log2) (4.22) during August and the lowest (2.91) during June. Stations I and III showed comparatively higher abundance and diversity of fishes. Variability in seagrass habitat structure and the interaction with coral reefs influenced the species composition and diversity of fishes in Minicoy Atoll. The findings of the present investigation can be used as baseline information for the fishery resource management of the region

Diversidade de macroalgas marinhas bentônicas dos recifes de Maracajaú, área de preservação ambiental dos recifes de corais, Rio Grande do Norte, Brasil

Despite the importance of coral reefs to humanity, these environments have been threatened throughout the world. Several factors contribute to the degradation of these ecosystems. The Maracajaú Reef Complex, in Rio Grande do Norte state is part of the Coral Reefs Environment Preservation Area in northeastern Brazil. This area has been receiving an increasing influx of tourism and the integrity of the local reefs is a matter of concern. In this study, the reef macroalgae communities were studied and compared within two areas distinguished by the presence or absence of tourism activities. Two sample sites were chosen: the first one, where diving activities are intense; and the other, where these practices do not occur. Samples were collected at both sites within a quadrate of 625 cm2 of area randomly thrown 5 times along a 10 meters transect line. Richness, Shannon-Hill diversity and Simpson dominance indices were determined based on biomass data. Similarity between sites was analyzed with Bray-Curtis similarity and distance index. Fifty-eight macroalgae species were observed, including 7 Chlorophyta, 13 Phaeophyta and 38 Rhodophyta. In the non-disturbed site, 49 species were found, while at the disturbed site, there were 42 species. Dictyotaceae and Corallinaceae were the most representative families at the non-disturbed site, and Rhodomelaceae and Dictyotaceae at the disturbed site. The non-disturbed site presented a higher biomass and the greatest richness and diversity indices. In the disturbed site the dominance index was greater and Caulerpa racemosa was the dominant species. The dendogram based on similarity index showed two major clusters, and an isolated element at the center that corresponds to a sample from the disturbed site. In the first cluster, samples from the non-impacted site were predominant and fleshy brown algae were more conspicuous. The second cluster was composed primarily of samples from the impacted site, where C. racemosa and red filamentous and erect calcareous algae associations (turf forming) were observed covering large extensions. These associations are represented by groups of algae adapted to environments where disturbances are frequent. They can grow rapidly on substrate where benthic community was removed and do not allow the establishment of other species. The results of the present study show that tourism activity is an impacting factor that has been causing shifts in macroalgae communities in the Maracajaú Reef Complex

Avaliação espaço-temporal do zooplâncton da laguna estuarina de Guaraíras (RN, Brasil)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Distribution and habitat preference of Carabidae and Staphylinidae (Coleoptera) in an orange orchard and a forest fragment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)