Observations on Fisheries Activities at Navassa Island

Unmanaged and unquantified artisanal fishing is ongoing at Navassa Island, a small oceanic island about 70 km west of Haiti that is part of the U.S. Caribbean Islands National Wildlife Refuge. Concern has been expressed regarding the possible impact of these fishing activities on reef resources, and no quantitative catch or effort data are available. However, informal qualitative observations made during a cruise in November 2002 suggest that escalation in fishing activity (and impact) has occurred since previous observations made in April 2000. Namely, size structure of fish was markedly reduced and the adoption of net fishing has allowed the exploitation of queen conch, Strombas gigas, and hawksbill turtles, Eretmochelys imbricata.

A Preliminary Study of the Marine Biota at Navassa Island, Caribbean Sea

A preliminary study of reef fish and sharks was conducted at Navassa Island in the Caribbean Sea during a 24-h period beginning 9 September 1998. Conducting a study at Navassa Island was of particular interest because exploitation of Navassa Island’s fishery resources has been considered minimal due to its remote location (southwest of the Windward Passage, Caribbean Sea) and lack of human habitation. Reef fish (and associated habitats) were assessed with stationary underwater video cameras at 3 survey sites; sharks were assessed by bottom longlining at 5 survey sites. Fifty-seven reef fish identifications to lowest possible taxon were made from video footage. Longline catches produced 3 shark species and 3 incidental catch species. When results from the 1998 National Marine Fisheries Service (NMFS) project are combined with a previous 1977 NMFS survey of Navassa Island, 27 fish families, 79 fish identifications to lowest possible taxon, 4 invertebrate orders or families, 3 coraline families, and 2 macroalgae phyla are reported.

Modern dinoflagellate cysts found in surface sediments of Santa Cruz Island, Galapagos

Modern dinoflagellate cysts in surface sediments collected on Santa Cruz Island, Galapagos, are described, along with other palynomorphs such as microforaminiferal linings, tintinnid loricae, copepod eggs and acritarchs including Domasiella-like micro-remains and Halodinium spp. The dinoflagellate cyst assemblages mainly consisted of Spiniferites cf. scabratus (gonyaulacoid) followed by Brigantedinium spp. and Selenopemphix quanta (peridinioids). No gymnodinioid cysts were found. No remarkable differences in cyst composition and densities were recognized between stations. The cyst assemblages were characterized by low species diversity and low cyst concentrations in comparison with the Pacific coast of Guatemala and Peru. CDF Contribution Number 1019.

Local distribution patterns of Opuntia echios echios, Bursera graveolens and Scalesia crockeri on Santa Cruz Island, Galapagos

We mapped stems of three plant species in a 2.36 ha plot in the arid zone near the coast of eastern Santa Cruz Island, Galapagos, Ecuador, to determine factors influencing their local distribution. The three species were Opuntia echios var. echios (Cactaceae), a large cactus, Bursera graveolens (Burseraceae), a small tree that dominates dry woodland near the coast, and the shrub Scalesia crockeri (Asteraceae). In our plot, Opuntia was most abundant near the coast, while Bursera and Scalesia increased in density inland and with increased relief. Scalesia also increased in density with increases in Bursera and decreases in other woody plants and was most abundant 200–250 m from the coast. Both Opuntia and Bursera were clumped in the plot as a whole but selected stem size classes were randomly dispersed within homogeneous portions of the sample area. CDF Contribution Number 1012.

The cost of quinine Cinchona pubescens control on Santa Cruz Island, Galapagos

We analyse the cost of controlling the invasive quinine tree Cinchona pubescens Vahl in the highlands of Santa Cruz Island, Galapagos. Control costs in ten 400 m2 plots formed the basis for estimating the cost of control over the whole island. In the plots, densities were 2100–24,000 stems/ha (stems >150 cm tall) and 55,000–138,000 stems/ha (all size classes combined). Control involved uprooting small plants, and applying of a mix of metsulfuron methyl and picloram to cut stumps or to machete cuts in the bark of larger trees. These methods are presently used by Galapagos National Park field crews to control quinine. Costs (in man hours, herbicide and US$) were related to stem density; the density of stems summed across four height classes was a better predictor of costs than density of any one size class. Regressions (on all size classes combined) formed the basis for predictive models of costs. Costs ranged from $14 to $2225 per ha depending on stem density. The amount of herbicide (active ingredient/ha) that must be applied to high density stands of quinine is higher than typical rates of application in an agricultural setting. The cost of treating all existing plants once across quinine’s known range on Santa Cruz Island (c. 11,000 ha) was estimated at c. US$1.65 million. CDF Contribution Number 1013.

Gestão Ambiental apoiada por SIG na estrada da Colônia, Ilha Grande (RJ): uma visão do futuro.

Os SIG Sistemas de Informação Geográfica vêm sendo cada vez mais estudados como ferramentas facilitadoras de análises territoriais com o objetivo de subsidiar a gestão ambiental. A Ilha Grande, que pertence ao município de Angra dos Reis, localiza-se na baía de Ilha Grande no sul do estado do Rio de Janeiro e constitui-se no recorte espacial de análise. Apresenta uma dinâmica ambiental complexa que se sobrepõem principalmente aos usos de proteção ambiental e de atividade turística em uma porção do território em que as normatizações legais são difíceis de serem aplicadas, pois são reflexos de interesses que se manifestam em três esferas do poder a municipal, a estadual e a federal. O objetivo principal desta pesquisa é a realização do processamento digital de imagem para auxiliar a gestão territorial da Ilha Grande. Em foco, a estrada Abraão - Dois Rios, que liga Abraão (local de desembarque dos turistas, principal núcleo da Ilha) a Dois Rios (local de visitação por estudantes e pesquisadores, núcleo que abrigava o presídio, atualmente abriga sede do centro de pesquisa e museu da Universidade do Estado do Rio de Janeiro), ambos protegidos por diferentes categorias de unidades de conservação. A metodologia fundamenta-se no processamento digital de imagem através da segmentação e da classificação supervisionada por pixel e por região. O processamento deu-se a partir da segmentação (divisão de uma imagem digital em múltiplas regiões ou objetos, para simplificar e/ou mudar a representação de uma imagem) e dos processos de classificações de imagem, com a utilização de classificação por pixel e classificação por regiões (com a utilização do algoritmo Bhattacharya). As segmentações e classificações foram processadas no sistema computacional SPRING versão 5.1.7 e têm como objetivo auxiliar na análise de uso da Terra e projetar cenários a partir da identificação dos pontos focais de fragilidade encontrados ao longo da estrada Abraão-Dois Rios, propensos a ocorrências de movimentos de massa e que potencializam o efeito de borda da floresta e os impactos ambientais. A metodologia utilizada baseou-se em análise de campo e comparações de tecnologias de classificação de imagens. Essa estrada eixo de ligação entre os dois núcleos tem significativa importância na história da Ilha, nela circulam veículos, pesados e leves, de serviço, pedestres e turistas. Como resultados da presente foram gerados os mapas de classificação por pixel, os mapas de classificação por região, o mapa fuzzy com a intersecção dos mapas de classificação supervisionada por região e os mapas com os locais coletados em campo onde são verificadas ocorrências de movimentos de massa nas imagens ALOS, 2000, IKONOS, 2003 e ortofotografias, 2006. Esses mapas buscam servir de apoio à tomada de decisões por parte dos órgãos locais responsáveis.