FCAA - Faculdade de Ciências Agrárias e do Ambiente
Permanent URI for this community
Browse
Browsing FCAA - Faculdade de Ciências Agrárias e do Ambiente by Subject "Abundance"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- Habitat use by the juvenile dusky grouper Epinephelus marginatus and its relative abundance, in Santa Catarina, BrazilPublication . Machado, Leonardo F.; Bertoncini, Áthila A.; Hostim-Silva, Maurício; Barreiros, João P.The dusky grouper (Epinephelus marginatus) is a species whose stock management deserves special attention. It has an important role in hard-bottom ecosystems and, as a protogynous hermaphrodite; it is especially susceptible to overfishing. Data on the species’ use of habitat, and on the way environmental and behaviour parameters influence its abundance can help to improve management and conservation strategies. The aim of this study was to evaluate the influence of bottom type, temperature and species behaviour on the abundance of E. marginatus, using a quadrate for visual census. An area of 80 mq., divided between rocky shore, rocky outcrop and sandy habitats was surveyed monthly. Densities of juveniles were: 1.16 groupers mˉ² over the rocky shore and 1.47 groupers mˉ² over the rocky outcrop, while no groupers were found over sand. Analysis of the yearly variation in abundance revealed a migratory pattern of dispersal and gathering. All size groups observed in this study were below the first maturation length.
- Perspectives and progress of ecology and conservation science in the Azores: the possible contribution of Artificial IntelligencePublication . Borges, Paulo A. V.; Cardoso, Pedro; Guerreiro, Orlando; Rigal, François; Florencio, Margarita; Amorim, Isabel R.; Borda-de-Água, Luís; Cascalho, José Manuel; Ferreira, MiguelThere is an urgent need of new methodologies in ecological and conservation science to deal with increasingly complex problems. We introduce four emerging research areas in ecology in which Artificial Intelligence may be explored as a tool to tackle unsolved issues in island ecosystems: (1) modeling abundance of plant and animal species in space and time; (2) modeling spread of invasive species; (3) estimating species richness based on incomplete sampling and (4) modeling speciation and diversification in insular habitats.
- Response of Common and Rare Beetle Species to Tree Species and Vertical Stratification in a Floodplain ForestPublication . Haack, Nora; Borges, Paulo A. V.; Grimm-Seyfarth, Annegret; Schlegel, Martin; Wirth, Christian; Bernhard, Detlef; Brunk, Ingo; Henle, Klaus; Pereira, Henrique M.Vertical stratification and host tree species are factors with a high influence on the structure of communities of xylobiont beetles. However, little is known about how this influence varies between common and rare species. Based on estimated species richness, we compared alpha and beta diversity patterns of common and rare species in the canopy of the Leipzig floodplain forest to assess their response to vertical stratification and tree species. We used two measures of rarity: threat level in red lists and abundance based on octaves. The understory displayed a significantly higher number of common species than the canopy strata. Conversely, the canopy strata harbored a higher number of rare species. Turnover was always dominant over richness differences in beta diversity partitions. Using Raup–Crick null models and non-metric multidimensional scaling, we found that the vertical strata accounted for 19% of the overall beta diversity of common species and for 15% of the overall beta diversity of rare species. The tree species accounted for 7% of the overall beta diversity of the common species and 3% of the beta diversity of the rare species. Our results indicate that studies carried out in the understory alone do not allow drawing conclusions regarding the biodiversity in the canopy strata, and thus regarding the overall community structure of xylobiont beetles in the canopy.
- Space-time distribution of the ichthyofauna from Saco da Fazenda estuary, Itajaí, Santa Catarina, BrazilPublication . Barreiros, João P.; Branco, Joaquim O.; Freitas Jr, Felipe; Machado, Leonardo F.; Hostim-Silva, Maurício; Verani, José R.A Ictiofauna do estuário Saco da Fazenda foi estudada mensalmente entre julho de 2003 e junho de 2004 em quatro áreas definidas em função das características fisiográficas e da representatividade do estuário nesta região. Foram capturados 4502 exemplares, distribuídos em 42 espécies, 35 gêneros e 21 famílias. Engraulidae foram os peixes mais abundantes, onde Cetengraulis edentulus dominou nas capturas. As espécies de ocorrência ocasional, representadas, principalmente por indivíduos juvenis, predominaram nas amostragens. As maiores abundâncias ocorreram durante os meses de verão e outono, em contraste com as elevadas biomassas na primavera-outono; sendo que a área IV diferenciou-se das demais, por contribuir com as maiores capturas. Os índices de riqueza, diversidade e equitabilidade, apresentaram padrões semelhantes de flutuação, com valores elevados nos meses de primavera e verão. O índice de Jaccard revelou uma maior similaridade na composição da ictiofauna entre as áreas II e IV, enquanto a menor ocorreu entre I e IV, provavelmente devido às diferentes áreas destes locais.