Background The oldest reference to marine life in Formigas Islets (oriental group of the Azores archipelago) goes back to the XVI century. Nevertheless, their macroalgal flora is poorly known, the published information mainly resulting from occasional collections of sporadic visitors. To overcome this and contribute to the knowledge of Azorean macroalgal flora at both local and regional scales, a thorough investigation was conducted in 1990 and 1991 under two expeditions promoted by the Marine Biology Research Group of the Department of Biology, University of the Azores. Collections and presence data recordings were done at the littoral and sublittoral levels down to approximately 40 m, in an area of approximately 0.04 Km2. This paper lists the taxonomic records and provides information regarding each species’ ecology and occurrence on the islets’ littoral.
New information A total of 320 specimens are registered (including taxa identified only at generic level) belonging to 90 taxa of macroalgae, from which 70 were diagnosed at species level. The confirmed species comprise 39 Rhodophyta, 12 Chlorophyta and 19 Ochrophyta (Phaeophyceae), distributed by 22 orders (13 Rhodophyta, 3 Chlorophyta and 6 Ochrophyta) and 37 families (24 Rhodophyta, 6 Chlorophyta and 7 Ochrophyta). Sixty-one species represent new records for the islets, from which Botryocladia macaronesica Afonso-Carrillo, Sobrino, Tittley & Neto and Laurencia viridis Gil-Rodriguez & Haroun are Macaronesian endemisms. Most species are native to the Azores, but six have an uncertain origin and four are introduced (the Rhodophyta Asparagopsis armata Harvey; Laurencia dendroidea J.Agardh; Neoizziella divaricata (C.K.Tseng) S.-M.Lin, S.-Y.Yang & Huisman; and the Ochrophyta Hydroclathrus tilesii (Endlicher) Santiañez & M.J.Wynne).
Introduction The Formigas Islets are located about 20 miles NE of Santa Maria Island and 34 miles SE of São Miguel Island (oriental group of Azorean archipelago, approximately 37°16′35″N, 24°46′54″W). They are arranged in a N-S direction, over a total length of about 165 m and a width of 80 m. Together with the submersed bank of Dollabarat, they form the Nature Reserve of Formigas Bank (DLR n° 11/88/ A). The oldest reference to life in Formigas Islets consists of descriptions of its marine fauna in the XVI century manuscript "Saudades da terra" written by the naturalist clergyman Gaspar Frutuoso. Subsequently, these islets were occasionally studied in sporadic visits by researchers, the first reference to the marine macroalgae being that of Piccone (1889). After that, several expeditions were made in order to study of the fauna and flora of the islets, which resulted in a few publications (see revision in Azevedo et al. 1991). An important finding was the first Azorean record of the brown alga Laminaria ochroleuca Bachelot de la Pylaie made by Ardré et al. (1973). Despite these efforts, the algal flora of these islets remained poorly known until the nineties, when a thorough investigation conducted by the Marine Biology Research Group of the Department of Biology, University of the Azores took place. This research group went to the islets in 1990 and 1991 and undertook collections and presence data recordings at the littoral and sublittoral levels down to approximately 40 m, in an area of approximately 0.04 Km2.
Purpose This paper, aimed at contributing to a better understanding of the seaweed flora of the Azores archipelago, lists the macroalgae recorded on surveys undertaken at Formigas Islets (Azores, eastern group) and presents a general information for each taxon’s occurrence on the islets’ littoral, thus contributing to address several biodiversity shortfalls (see Hortal et al. 2015), namely the need to catalogue the Azorean macroalgae (Linnean shortfall) and improve the current information on their local and regional geographic distribution (Wallacean shortfall), as well as on species abundances and dynamics in space (Prestonian shortfall). It is intended as a resource for academics, students, government, private organizations, and the general public, and also as a practical basis for biological studies such as systematics, diversity and conservation, biological monitoring, climate change and ecology.
The data in this sampling event resource has been published as a Darwin Core Archive (DwC-A), which is a standardized format for sharing biodiversity data as a set of one or more data tables. The core data table contains 8 records.
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Neto A I, Prestes A C L, Azevedo J M N, Resendes R, Álvaro N V, Neto R M A, Moreu I (2020): Marine algal (seaweed) flora of Formigas Islets, Azores. v1.8. Universidade dos Açores. Dataset/Samplingevent. http://ipt.gbif.pt/ipt/resource?r=formigas_seaweed_flora&v=1.8
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Macroalgae; seaweeds; Rhodophyta; Chlorophyta; Ochrophyta; Azores; Formigas Islets; endemism; native; introduced; uncertain; occurrence data.; Samplingevent
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Formigas Islets, Azores, Macaronesia, Portugal (approximately 37°16′35″N, 24°46′54″W).
|Bounding Coordinates||South West [37.269, -24.783], North East [37.276, -24.778]|
All macroalgae were identified to genus or species. In total, 90 taxa were identified comprising 71 confirmed species, belonging to 22 orders and 37 families, distributed by the phyla Rhodophyta (13 orders and 24 families), Chlorophyta (3 orders and 6 families) and Ochrophyta (6 orders and 7 families).
|Phylum||Rhodophyta (Red algae), Chlorophyta (Green algae), Ochrophyta (Brown algae)|
Aimed at improving the knowledge of Formigas Islets’ macroalgal flora, extensive collections were made in the years 1990 and 1991, covering the littoral and sublittoral levels down to approximately 40 m around the islets (total area of approximately 0.04 Km2). This paper lists the taxonomic records and provides information on each taxon’s ecology and occurrence on the islets’ littoral.
|Title||Marine algal (seaweed) flora of Formigas Islets, Azores|
|Identifier||Seaweeds of Formigas Islets (Azores)|
|Funding||This study was mainly financed by the following projects/scientific expeditions: • Expedition SANTA MARIA and FORMIGAS/90, Departamento de Biologia da Universidade dos Açores, Ilha de Santa Maria e Ilhéus das Formigas, Açores, June 1990; • Expedition FORMIGAS/91, Secção de Biologia Marinha do Departamento de Biologia da Universidade dos Açores, Ilhéus das Formigas, July 1991; • Project “ACORES-01-0145-FEDER-000072 - AZORES BIOPORTAL – PORBIOTA. Operational Program Azores 2020 (85% ERDF and 15% regional funds); • Portuguese National Funds, through FCT – Fundação para a Ciência e a Tecnologia, within the projects UID/BIA/00329/2019 and UID/BIA/00329/2020-2023; • CIRN/DB/UAc (Research Centre for Natural Resources, Universidade dos Açores, Departamento de Biologia).|
|Study Area Description||Located in the eastern group of the Azores archipelago, the Formigas Islets (37°16′35″N, 24°46′54″W) are approximately 20 miles NE of Santa Maria Island and 34 miles SE of São Miguel Island, thus being the most isolated islets of the Azores. Consequently, they are relatively protected from human action and function as a breeding and nursing ground for many marine species occurring in the Azorean waters (Costa et al. 1994). The islets, together with the submersed bank of Dollabarat, form the Formigas Bank, located between the parallels 37° 14'N and 37° 17'N and the meridians 24° 43'W and 24° 47'W, occupying an area about 7 miles long and 3 miles wide (Azevedo et al. 1991) which was constituted a Nature Reserve in 1988 (DLR n° 11/88/ A). Formigas Islets are located in the NW part of the bank. With a N-S arrangement, they have a total length of about 165 m and width of 80 m, with an area of compact rocks in the southern part and one of large blocks in the North. The highest block (Formigão) is 11 m high. In the South region there is a lighthouse, from which there are two small anchorages (Azevedo et al. 1991). The intertidal zone is narrow and mostly dominated by animals (e.g. gastropods, chthamalid barnacles, and decapods) and algal turfs (mostly composed by various species of Ceramium spp. and Gymnogongrus spp.), that are typically found in most of the islands. The many channels that cross the rocky platforms are dominated by luxuriant forms of the brown algae Cystoseira spp., Treptacantha abies-marina and Sargassum spp. At the low intertidal the algal turfs give rise to erect forms of algae, e.g. Elisolandia elongata. Subtidally, the rocky walls and rocky platforms are covered with erect, corticated macrophytes, e.g. Dictyota spp. and Plocamium cartilagineum. At and below 40 m depth the leathery brown algae Laminaria ochroleuca can form some monospecific patches(Neto, pers. observ.).|
|Design Description||The macroalgae referred to in this paper were collected during field studies at littoral and sublittoral levels down to approximately 40 m on the Formigas Islets, covering an area of 0.04 Km2. Intertidal collections were done at low tide by walking over the shore. Subtidal collections were done by scuba diving. Each sampling location was visited several times. In each time, a careful survey was made to allow a good coverage of the area. Whenever an unknown or potential new species was found, it was collected, given an individual registration number and vouchers deposited at the AZB Herbarium Ruy Telles Palhinha, based at the Faculty of Sciences and Technology of the University of the Azores.|
The personnel involved in the project:
Intertidal collections were made at low tide by walking over the shore. Subtidally collections were made by scuba diving. In each sampling location, one or two specimens of all different species found were scraped into labelled bags. Complementary data such as shore level (high, mid, low), orientation and type of substrate (bedrock, boulders, mixed), habitat (tide pool, open rock, gully, crevice) was also recorded.
|Study Extent||Collections were performed at littoral and sublittoral levels down to approximately 40 m around Formigas Islets in a total area of approximately 0.04 Km2.|
|Quality Control||Each sampled taxon was investigated by trained taxonomists with the help of keys and floras. This involved morphological and anatomical examination by eye or under the dissecting and compound microscopes of an entire specimen or slide preparation. In difficult cases specimens were sent to experts for identification.|
Method step description:
- In the laboratory the specimens were sorted and studied following standard procedures used in macroalgae identification. Species identification was based on morphological and anatomical characters and reproductive structures. For small and simple thalli, this required the observation of the entire thallus with the naked eye and/or using dissecting and compound microscopes. For larger and more complex algae, the investigation of thalli anatomy required histological work to obtain longitudinal and transverse sections needed for the observation of cells, reproductive structures and other diagnosing characters. Due to the mixed nature of the Azorean macroalgae, floras and keys from the Atlantic and Western Mediterranean were used for the species identification, e.g.: Schmidt (1931), Taylor (1967, 1978), Levring (1974), Dixon & Irvine (1977), Lawson & John (1982), Irvine (1983), Gayral & Cosson (1986), Fletcher (1987), Afonso-Carrillo & Sansón (1989), Burrows (1991), Boudouresque et al. (1992), Cabioc'h et al. (1992), Maggs & Hommersand (1993), Irvine & Chamberlain (1994), Brodie et al. (2007), Lloréns et al. (2012) and Rodríguez-Prieto et al. (2013). For more critical and taxonomically difficult taxa, specimens were taken to the Natural History Museum (London) for comparison with collections there, or sent to specialists. A reference collection was made for all specimens collected by giving them an herbarium code number and depositing them at the AZB Herbarium Ruy Telles Palhinha, University of Azores. Depending on the species and on further research planned, different types of collections were made, namely (i) liquid collections using 5% buffered formaldehyde seawater and then replacing it by the fixing agent Kew (Bridsen & Forman 1999); and (ii) dried collections, either by pressing the algae (most species) following the method described by Gayral and Cosson (1986). Nomenclatural and taxonomic status used here follow Algaebase (Guiry & Guiry, 2020). The database was organized on FileMaker Pro.
|Collection Name||AZB | Marine macroalgae collection of Formigas Islets - Expedition SANTA MARIA and FORMIGAS/90|
|Parent Collection Identifier||AZB Herbarium Ruy Telles Palhinha, Faculty of Sciences and Technology of the University of the Azores.|
|Collection Name||AZB | Marine macroalgae collection of Formigas Islets - Expedition FORMIGAS/91|
|Parent Collection Identifier||AZB Herbarium Ruy Telles Palhinha, Faculty of Sciences and Technology of the University of the Azores.|
|Specimen preservation methods||Dried and pressed, Dried, Other, Formalin|
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Additional information on this study may also be requested to the first author.