IMIS

The goal of the PELD-ILOC is to provide long-term research to the scientific community, policymakers, and society with the knowledge and predictive understanding necessary to conserve, protect, and manage the Brazilian oceanic islands ecosystems, their biodiversity, and the services they provide. This dataset compiles data from 2006 to 2019 gathered from all four islands at different depths and sites and is related to reef fish (Actinopterygii) species occurrence, size and abundance.

Project Data

Brazil has four tropical oceanic islands: St. Peter and St. Paul’s Archipelago, Fernando de Noronha Archipelago, Rocas Atoll and Trindade Island and Martin Vaz Archipelago. These islands are geographically highly isolated, experience less harmful human-driven impacts than the coastal area, and encompass different levels of protection. Therefore, these more pristine islands represent a fundamental reservoir of marine biodiversity not only to the country but to the whole world. However, the Brazilian oceanic islands remain unknown to the majority of the population. Our mission is to increase the awareness and interest among Brazil’s population, providing knowledge to support governmental decisions and thereby help to protect and preserve the diversity, manifoldness and health of the unique marine ecosystems of our oceanic islands. Our objective is to understand how ecosystem structures of reef communities at the four Brazilian oceanic islands change under a variety of human-driven impacts, such as fishing, pollution or climate change. Hence, PELD – ILOC monitors the Brazilian oceanic islands to continuously assess the dynamics of reef communities and populations and the processes driving these dynamics.

Title    Long-term Ecological Monitoring Research Brazilian Oceanic Islands
Identifier    PELD-ILOC
Funding    Brazilian National Council for Scientific and Technological Development (CNPq, Portuguese: Conselho Nacional de Desenvolvimento Científico e Tecnológico) grant #441241/2016-6.

Study Area Description    Fernando de Noronha Archipelago (FNA) is composed of the main island and other 20 smaller islands located of volcanic origin, ~350 km offshore the Brazilian coast. FNA’s reefs are usually shallow (< 60 m), steep and highly exposed to wave action. The reef benthic community at depths up to 30 m is mainly composed of turf algae and macroalgae, besides the high cover of articulated coralline algae and crustose coralline algae.Saint Peter and Saint Paul Archipelago is a tiny immerse tip of the Mid-Atlantic Ridge, also composed of the main island (~120 m^2) and a set of 15 islets, ~1010 km from the northeastern coast of Brazil, and 650 km east from FNA. The inlet on the main island is the most sampled site and varies from 3 to 27 m deep. Rocas Atoll (RA) is the only atoll in the South Atlantic and is considered the smallest atoll in the world. It is located 266 km off the Brazilian coast and 124 km west of FNA. A large part of the atoll is directly under the influence of the local high tides (up to 3.8 m) which forms tide pools of diverse volumes. Monitoring sampling is conducted in the tide pools because of the difficult access to the outer reef.Finally, Trindade Island (TI) is also of volcanic origin, formed by an emerged tip of the Vitória-Trindade Seamount Chain, at 1140 km off the eastern coast of Brazil. Winds prevailing from NE to E lead to greater exposure of the eastern side to waves and erosion of the rocky shore, and favouring the monitoring of most sites on the leeward side of the island.  Ascension island is also of volcanic origin, with steep shores, and three sites were sampled only once in 2015.
 

Design Description    For FNA has three sites are monitored on the leeward side of the main island (Cagarras, Sapata and Laje Dois Irmãos), with depths ranging from 1 to 30 m. The SPSPA has only one monitoring site in the main island inlet, with depths from 5 to 35 m. Trindade Island is monitored in four sites at the leeward side of the island, on depths from 3 to 20 m. In each site of the monitored sites, at least 25 transects for fish counting are conducted each year since 2013. However, data from other sites on each island and of a greater depth range are available in this dataset because there were favourable conditions for exploring new sites during some expeditions. Ascension island had only three sites sampled once in 2015 with surveys taken between 4 and 13 m deep.

Sampling Methods

Underwater visual surveys (UVS) were used to count fish in 20m×2m×2m (length× width × height) strip transects made while free or scuba diving. During a UVS the diver unwound a tape while identifying, counting and estimating the total length (LT, cm) of non-cryptic fishes >10 cm. Then, while retracting the tape, following the same procedure for benthic-associated non-cryptic fishes <10 cm and cryptic species. The size was estimated with a precision of 1 cm for fishes <10 cm LT, 5 cm for fishes between 10 and 60 cm and 10 cm for fishes >60 cm. Solitary individuals, pairs or small schools (tens of individuals) were counted; intermediate-sized schools (tens to hundreds of individuals) were estimated with a precision of 10 individuals and large schools (many hundreds) with a precision of 50 individuals. For large schools, the number of individuals in a quarter of the area the school occupied were estimated and multiplied by four. Schools that crossed the sampled area were counted integrally, even if the school was larger than the area occupied by the transect. Since maximum water visibility was usually much lower than the transect length, counts of species were not instantaneous, but rather gradual at 3–6 m ahead of the diver depending on visibility. Adapted from Morais et al. (2017) DOI: 10.1111/jfb.13482

Study Extent    All Brazilian Oceanic islands have been surveyed once a year since the start of the PELD ILOC project in 2013, but some islands have previous data from collaborating projects or researchers, such as FNA (2007, 2011), RA (2006), SPSPA (2009, 2011, 2012) and TI (2007, 2009, 2011, 2012). Ascension Island was sampled once in 2015.
Quality Control    Details about the quality control can be found at: https://github.com/peld-iloc/Dwc-A_reef_fishes_PELD.
Method step description  Details about the data processing can be found at: https://github.com/peld-iloc/Dwc-A_reef_fishes_PELD.