Predictive Modeling of Dominant Macroalgae Abundance on Temperate Island Shelves (Azores, Northeast Atlantic)
Volcanic oceanic islands typically rise steeply from the ocean floor and are surrounded by narrow shelves produced by swell erosion on the islands' flanks. This chapter focuses on mapping the distribution of six macroalgae that dominate infralittoral on-shelf hard substrate biotopes around the...
| Main Authors: | , , , , , |
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| Format: | Book Part |
| Language: | English |
| Published: |
2012
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| Subjects: | |
| Online Access: | https://risweb.st-andrews.ac.uk/portal/en/researchoutput/predictive-modeling-of-dominant-macroalgae-abundance-on-temperate-island-shelves-azores-northeast-atlantic(e9d917a9-b9f0-4b69-9705-94f535b91dfc).html https://doi.org/10.1016/B978-0-12-385140-6.00008-6 http://www.scopus.com/inward/record.url?eid=2-s2.0-84861383376&partnerID=8YFLogxK |
| Summary: | Volcanic oceanic islands typically rise steeply from the ocean floor and are surrounded by narrow shelves produced by swell erosion on the islands' flanks. This chapter focuses on mapping the distribution of six macroalgae that dominate infralittoral on-shelf hard substrate biotopes around the island of Faial (Azores, northeast Atlantic): articulated Corallinaceae, Codium elisabethae, Dictyota spp., Halopteris filicina, Padina pavonica, and Zonaria tournefortii. Semi-quantitative data on their abundance, collected by SCUBA diving, ROV, and drop-down camera surveys, are intersected with a series of gemorphological and oceanographical explanatory variables collated from various sources that include multibeam surveys, satellite imagery, oceanographic modeling, and GIS analysis. Ordered logistic regression models are used to find the combinations of major environmental variables that best explain the abundance variations observed. The predictive distribution maps obtained for the six macroalgae are combined to produce the first predictive map of macroalgal facies on an island shelf in the Azores. Depth-wise general and sectoral macroalgal zonation are also presented. The seafloor of the area has been mapped in high resolution using swath sonars, providing an opportunity to infer the distribution of benthic species associated with the shelf habitats. In this perspective, semi-quantitative data on infralittoral macroalgae living on hard substrates were brought together from a number of biological surveys and related to geomorphological and oceanographic variables. The statistical modeling of biological distributions focused on six taxa belonging to the three groups of macroalgae dominating infralittoral hard substrates in the Azores: calcareous red algae, brown algae and, to a lesser extent, green algae has been explained. |
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