Abundance estimation of rocky shore invertebrates at small spatial scale by high-resolution digital photography and digital image analysis

Pech, Daniel; Condal, A.; Bourget, Edwin; Ardisson, Pedro-Luis

doi:10.1016/j.jembe.2003.08.017

Cited by 43 publications

(34 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The main advantage in the digital photograph method is the fast estimation of abundance, in addition to quickening the capture of images, which can be visualized and retaken at the same time, still in situ. It is well known that time is a critical factor in conducting experiments and observations in intertidal zone specially due to the duration of the tidal cycle (Meese & Tomich, 1992;Dethier et al, 1993;Pech et al, 2004). The field time reduction is essential for the study of a larger area and for the increase of sample units.…”

Section: Discussionmentioning

confidence: 99%

“…As the images can be stored in disks, the authors suggest the digital technique to form a data bank, similar to that currently used for satellite images. Digital tools could substantially lower the cost of monitoring programs for which a fast acquisition data rate is needed at any spatial scale and improve the estimates of the ecological properties of the community (Pech et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Comparison of rocky itertidal community sampling methods at northern coast of Rio de Janeiro State, Brazil

2006

View full text Add to dashboard Cite

The purpose of this study is to compare different rocky intertidal sampling methods at the northern coast of the Rio de Janeiro State. Quadrats with 50 and 100 intersection points were sampled in field and in computer using digital photos. A similarity over 90% was obtained between both methods for the intertidal zone. Cluster analysis showed that the lower sample size overestimated some indicator organisms. The zonation pattern through photo sampling was different from that in field especially in Supralitoral Fringe due to the color similarity of Chthamalus sp with bare substrate. The main advantages of the digital method are the fast abundance estimation, the possibility of comparison among researchers and the permanent community record. However, there is a potential for species misidentification with similar color morphotypes. In zonation intertidal studies, digital photograph sampling method is suggested since it is rather efficient, accurate and advantageous in relation to the field method. Such a choice might be made after the previous knowledge of local organisms and should be adequate to the final objectives.
A proposta do presente estudo é comparar diferentes métodos de amostragem da comunidade bêntica no entremarés em substrato rochoso na costa norte do Estado do Rio de Janeiro. Quadrados com 50 e 100 pontos de interseção foram amostrados no local e em computador por fotografia digital Uma similaridade superior a 90% foi obtida entre ambos os métodos em cada altura do substrato. A análise de agrupamento evidenciou que o menor tamanho amostral superestimou alguns organismos indicadores. O padrão de zonação através da amostragem por foto foi diferente daquele no campo principalmente na Franja do Supralitoral face à similaridade de coloração de Chthamalus sp com o substrato vazio. O método por foto tem como principais vantagens a rápida estimativa de abundância, a possibilidade de comparação entre observadores e o registro permanente da comunidade. Contudo, há a possibilidade de má identificação de morfotipos de cores semelhantes e não permite a amostragem de vários estratos. Para estudos de zonação a amostragem por fotografia digital é bastante eficiente, acurada e vantajosa em relação ao método em campo. Mas, tal opção procede após o conhecimento prévio dos organismos e deve ser adequada aos objetivos finais

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Comparison of rocky itertidal community sampling methods at northern coast of Rio de Janeiro State, Brazil

2006

View full text Add to dashboard Cite

show abstract

“…Species counted as individuals per square meter were anemones, chitons, herbivorous snails, limpets, mussels, and sea stars. The use of digital photographs is widely accepted as an appropriate technique to estimate the abundance of marine subtidal and intertidal organisms (40,41).…”

Section: Methodsmentioning

confidence: 99%

Introduced rats indirectly change marine rocky intertidal communities from algae- to invertebrate-dominated

Kurle

Croll

Tershy

2008

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

It is widely recognized that trophic interactions structure ecological communities, but their effects are usually only demonstrated on a small scale. As a result, landscape-level documentations of trophic cascades that alter entire communities are scarce. Islands invaded by animals provide natural experiment opportunities both to measure general trophic effects across large spatial scales and to determine the trophic roles of invasive species within native ecosystems. Studies addressing the trophic interactions of invasive species most often focus on their direct effects. To investigate both the presence of a landscape-level trophic cascade and the direct and indirect effects of an invasive species, we examined the impacts of Norway rats (Rattus norvegicus) introduced to the Aleutian Islands on marine bird densities and marine rocky intertidal community structures through surveys conducted on invaded and rat-free islands throughout the entire 1,900-km archipelago. Densities of birds that forage in the intertidal were higher on islands without rats. Marine intertidal invertebrates were more abundant on islands with rats, whereas fleshy algal cover was reduced. Our results demonstrate that invasive rats directly reduce bird densities through predation and significantly affect invertebrate and marine algal abundance in the rocky intertidal indirectly via a cross-community trophic cascade, unexpectedly changing the intertidal community structure from an algae-to an invertebratedominated system. community structure ͉ invasive species ͉ Rattus norvegicus ͉ trophic cascade ͉ marine birds H airston et al.(1) laid the theoretical framework for the role of trophic interactions in structuring ecological communities, whereby carnivores keep herbivores in check via predation that releases plants from heavy grazing pressure, thus resulting in a ''green world.'' As a result of their article and other seminal publications on the topic, much attention in community ecology has focused on the role of predators in structuring communities. Thus, the direct and indirect effects of top-level predators on community composition have repeatedly been demonstrated at the population or community level, but landscape-level illustrations of communities transformed by top predators via trophic cascades are still scarce (but see refs. 2-4). Vertebrate predators introduced to oceanic islands throughout an archipelago provide ecologists with opportunities to investigate the presence and extent of such cascades over larger spatial scales. Studies of invasive species on islands often demonstrate direct reductions in native species abundances (5-7), but it has proven more difficult to determine the indirect trophic effects mediated by invaders and the extent to which these trophic interactions alter native community composition. The presence of invaded and noninvaded islands within a single archipelago allows for the quantification of both direct and indirect impacts on native communities imposed by introduced species and provides an opportunity to ...

show abstract

“…The method presented here has shown itself to be very efficient for the intertidal community studies. Pech et al (2004) have already discussed the advantages of digital photography and the importance of aggregating technological advances to improve data acquisition in marine ecology. In this regard, we considered the continuous upgrade of the method described, by using better resolution cameras and adapting the acrylic box to suit cameras in underwater housings.…”

Section: Discussionmentioning

confidence: 99%

Method for monitoring intertidal communities in a steep rocky shore: a combination of digital image technology and field operational strategy

et al. 2007

View full text Add to dashboard Cite

A B S T R A C TThis paper introduces a method for temporal studies of steep rocky intertidal communities. It combines the use of digital image technology with field methodology, so that a wide area of the community can be sampled in a short time. Two current nondestructive percent cover estimation methods (visual estimation and point intersection) were compared in terms of cost, operational advantages and data quality, with a proposed method for a sucessional study . The proposed method used sequential photos to sample multiple fixed vertical transects over time. Reproduction of the midintertidal transect over time was possible by overlaying temporal transects in an image editing program. This method was similar to the point intersection quadrat method used to estimate percent cover. Benefits included reduced time on field work, economic advantages and other advantages of using digital photography, such as recording. Temporal photography of transects provided measurements of recruitment, mortality and population growth, and made it possible to manufacture an animation of sucessional stages. We suggest that this is the best method for providing information and understanding on the process of succession and for monitoring benthic invertebrate intertidal communities on steep rocky shores. R E S U M OEste trabalho apresenta uma metodologia para estudos temporais de comunidades entre-marés de costões rochosos com acentuada inclinação, associando tecnologia de captura de imagens digitais com uma estrutura operacional de campo, permitindo a amostragem de ampla faixa da comunidade, em pouco tempo. Dois métodos tradicionais de estimativa de porcentagem de cobertura (estimativa visual e pontos de interseção) foram usados para comparar a aplicabilidade do método proposto a um estudo de sucessão, quanto às vantagens econômicas, operacionais e qualidade dos dados obtidos. O método permite a amostragem temporal de múltiplos transectos verticais específicos, por meio de fotos seqüenciais. As mesmas são fundamentais para a posterior montagem da imagem do transecto num programa de edição de imagem através da compilação das fotos e sobreposição temporal dos transectos. Este método obteve resultados similares ao método de pontos de interseção quanto às leituras de porcentagem de cobertura, além de reduzido tempo em campo, vantagens econômicas e vantagens do uso das fotografias digitais. A análise das transições temporais permitiu a obtenção de parâmetros como recrutamento, mortalidade e crescimento populacional, além da montagem de uma animação com a sucessão. Consideramos esta metodologia a mais indicada para estudos de sucessão ecológica, especialmente no monitoramento de comunidades de invertebrados bentônicos do médiolitoral, em costões de inclinação acentuada.

show abstract

Abundance estimation of rocky shore invertebrates at small spatial scale by high-resolution digital photography and digital image analysis

Cited by 43 publications

References 18 publications

Comparison of rocky itertidal community sampling methods at northern coast of Rio de Janeiro State, Brazil

Comparison of rocky itertidal community sampling methods at northern coast of Rio de Janeiro State, Brazil

Introduced rats indirectly change marine rocky intertidal communities from algae- to invertebrate-dominated

Method for monitoring intertidal communities in a steep rocky shore: a combination of digital image technology and field operational strategy

Contact Info

Product

Resources

About