A dataset on the species composition of amphipods (Crustacea) in a Mexican marine national park: Alacranes Reef, Yucatan

Abstract Background Alacranes Reef was declared as a National Marine Park in 1994. Since then, many efforts have been made to inventory its biodiversity. However, groups such as amphipods have been underestimated or not considered when benthic invertebrates were inventoried. Here we present a dataset that contributes to the knowledge of benthic amphipods (Crustacea, Peracarida) from the inner lagoon habitats from the Alacranes Reef National Park, the largest coral reef ecosystem in the Gulf of Mexico. The dataset contains information on records collected from 2009 to 2011. Data are available through Global Biodiversity Information Facility (GBIF). New information A total of 110 amphipod species distributed in 93 nominal species and 17 generic species, belonging to 71 genera, 33 families and three suborders are presented here. This information represents the first online dataset of amphipods from the Alacranes Reef National Park. The biological material is currently deposited in the crustacean collection from the regional unit of the National Autonomous University of Mexico located at Sisal, Yucatan, Mexico (UAS-Sisal). The biological material includes 588 data records with a total abundance of 6,551 organisms. The species inventory represents, until now, the richest fauna of benthic amphipods registered from any discrete coral reef ecosystem in Mexico.


Introduction
Alacranes Reef is a highly diverse protected coral reef ecosystem, located in the southern sector of the Gulf of México. It is considered as one of the largest coral reefs of the Gulf of Mexico (Liceaga-Correa and Hernández-Núñez 2000, Tunnell et al. 2007a). It was declared as a National Marine Park by the Mexican government in 1994 and as a Biosphere Reserve, by the UNESCO, in 2006. Since its declaration as a National Park, Alacranes Reef has been subject to different efforts to inventory its biodiversity, however, this task is not fulfilled until now. Recent studies on reef-associated benthic fauna include sea anemones (González-Muñoz et al. 2013), decapod crustaceans (Santana-Moreno et al. 2013), polychaetes (Ramírez-Hernández et al. 2015), sponges (Ugalde et al. 2015) and mollusks (Reyes-Gómez et al. 2017).The peracarid crustaceans, such as the amphipods, are one of the underestimated groups not considered in the main inventory lists reported for the reef (CONANP 2006, Tunnell et al. 2007b). The scarce evidence describing the richness of amphipods on the Alacranes reef (Paz-Ríos et al. 2014, Paz-Ríos et al. 2013a, Paz-Ríos et al. 2013b) has pointed out the relevance of this group as one of the most diverse in the entire reef ecosystem. The present contribution intends to show the high species richness of benthic amphipods inhabiting the bottom habitats from the inner reef lagoon by providing a dataset with taxonomic checklist. This checklist constitutes the first formal effort to inventory the biodiversity of such group in the Alacranes Reef ecosystem.

Project description
Title: Alacranes Reef Biodiversity Expedition.

Design description:
The dataset was composed using information from benthic macrofauna samples randomly collected on different benthic habitats and artificial substrates between 2009 and 2011, mostly in the inner lagoon of Alacranes reef.
Funding: Resources included funds to NS from the National Autonomous University of Mexico (UNAM) for supporting academic research (PAPIME-PE207210), funds from the Mexican Government for scientific research (SEMARNAT-CONACyT108285) and an international cooperation for marine scientific research between Mexico and USA (HRI-CONABIO-NE018) through the project "Actualización del conocimiento de la diversidad de especies de invertebrados marinos bentónicos de aguas someras (<50 m) del Sur del Golfo de México". Funds to CEPR was provided by CONACyT scholarship.

Sampling methods
Study extent: The dataset contains information on amphipods collected from three different expeditions: the first one in August 2009, the second one in April 2010 and the third one in October 2011. In each expedition a relatively high diversity of habitats was explored in order to increase the chance to capture the species diversity. In the 2010 and 2011 expeditions, special effort was made to collect information on navigation buoys and two wood docks nearby a sand island (isla Perez).
Sampling description: Amphipods were collected from 50 sampling sites: Forty-one randomly distributed on natural habitats from the inner lagoon, including different benthic habitats (i.e. bare substrate, seagrass bed, coral patch, reef wall) and nine collected on artificial substrates (i.e. buoy, wood dock, lobster tramp). Diverse sampling devices were employed: PVC core for sandy substrates, shovel for patches of intertidal sand, suction device sampler for coral rubble, sand and shallow coral reef flats and, finally, a Riley pushnet and trawl for shallow seagrass beds of Thalassia testudinum (Banks ex König, 1805).
Quality control: Amphipod species were sorted and identified to the lowest possible taxonomical category, using specialised literature such as keys for identification, e.g. Myers (1981), Lowry and Stoddart (1997), LeCroy (2000) and illustrated guides, e.g. Winfield et al. (2007), Ortiz et al. (2014. The taxonomical arrangement used herein follows Lowry and Myers (2017). Nine species were identified as possibly new species and were represented at the genus category (i.e. Bemlos, Elasmopus, Idunella, Harpinia, Leucothoe, Maera, Psammogammarus); further specialised taxonomical effort will be needed before assigning a name. Species names were matched using the Taxon Match tool in the World Register of Marine Species (WoRMS) in order to corroborate, standardise and update if necessary. Sampling points in the reef, available in the Data resources (see below), were georeferenced and displayed into different maps using different software (i.e. QGIS , ArcView GIS , and Google Maps ).

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Step description: Once collected, the amphipods were first anaesthetised with magnesium chloride (4%) for 15 to 20 min. and then fixed with formaldehyde solution (10%) buffered with seawater before storage. In the laboratory, samples were washed through a 500 µm size mesh and preserved with 70% of ethanol solution. Finally, the organisms were stored in glass containers with a catalogue number according to the regional collection 'Crustáceos de Yucatán' (YUC-CC-255-11), from the 'Universidad Nacional Autónoma de México, Unidad Sisal' Mexico.

Taxonomic coverage
Description: The dataset contains information on 110 species (93 nominal species and 17 generic species), belonging to 71 genera, 33 families and three suborders. The suborder Amphilochidea was composed of 46 species, 28 genera and 13 families, the suborder 2 Figure 1.
Location of sampling points in the Alacranes Reef National Park. The image from the NASA Earth Observatory, was acquired by Jesse Allen on November 5, 2014, by the Operation Land Imager on Landsat 8.  The geographic latitude (in decimal degrees, using the spatial reference system given in geodeticDatum) of the geographic centre of a Location. decimalLongitude The geographic longitude (in decimal degrees, using the spatial reference system given in geodeticDatum) of the geographic centre of a Location.
identificationQualifier A brief phrase or a standard term ("cf.", "aff.") to express the determiner's doubts about the Identification.
scientificNameID An identifier for the nomenclatural (not taxonomic) details of a scientific name (i.e. AphiaID).

scientificName
The full scientific name. taxonRank The taxonomic rank of the most specific name in the scientificName.
taxonRemarks Comments or notes about the taxon or name.