Freshwater species of the Seychelles

Data Records

The data in this checklist 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 211 records.

This IPT archives the data and thus serves as the data repository. The data and resource metadata are available for download in the downloads section. The versions table lists other versions of the resource that have been made publicly available and allows tracking changes made to the resource over time.

Versions

The table below shows only published versions of the resource that are publicly accessible.

How to cite

Researchers should cite this work as follows:

Rose M, Henriette E (2024). Freshwater species of the Seychelles. Version 1.7. Gaea Seychelles. Checklist dataset. https://cloud.gbif.org/africa/resource?r=seychelles_freshwater_species_checklist&v=1.7

Rights

Researchers should respect the following rights statement:

The publisher and rights holder of this work is Gaea Seychelles. This work is licensed under a Creative Commons Attribution (CC-BY 4.0) License.

GBIF Registration

This resource has been registered with GBIF, and assigned the following GBIF UUID: ae8d236f-58e8-485e-a2c7-e1e8ac1d500d.  Gaea Seychelles publishes this resource, and is itself registered in GBIF as a data publisher endorsed by Participant Node Managers Committee.

Keywords

Checklist; Freshwater checklist; Freshwater fish; freshwater crustaceans; freshwater macro-invertebrates

Contacts

Geographic Coverage

The Republic of Seychelles A conglomerate of 115 islands situated in the Indian Ocean near the east coast of Africa

Taxonomic Coverage

No Description available

Project Data

The project aims to achieve a comprehensive freshwater biodiversity database to address conservation and management issues in the Seychelles. It will target notably freshwater fish, micro and macro invertebrates. The first component contributes aquatic data to the ‘Seychelles’ Holistic Biodiversity Database on species and ecosystems’ (Bio database) and the Global Biodiversity Information Facility (GBIF). Freshwater biodiversity data from scientific publications, museum collections etc will be compiled into the ‘Bio database’. The number of records and species in the databases will be the main measurable indicators. Component 2 targets baseline surveys and annual biodiversity inventories of fish, micro and macro invertebrates in 15 rivers including the collection of genetic materials through eDNA. All data collected will be integrated into the Bio database, eBioAtlas (https://ebioatlas.org/) and GBIF. The 3rd component is the Train-the-Trainer programme to advance the understanding of freshwater systems while developing capacity through internships, graduate programmes and guest lectures. 10 students from UniSey and 5 participants from participating organisations will be trained in identification of freshwater biodiversity, surveys, eDNA sampling and freshwater ecology and 2 Seychellois trained at graduate level in conservation of freshwater biodiversity. Component 4 is an outreach programme + Citizen Science for different target groups to raise awareness on the importance of freshwater ecosystems, and the production of 3 scientific publications of the status of freshwater biodiversity.

The personnel involved in the project:

Sampling Methods

15 principal perennial rivers are selected based on their importance in terms of length, size of water catchment and protected status, and their accessibility. These rivers will be surveyed once a year (minimum) twice a year during (North-west Monsoon and South-east Monsoon) using electrofishing methods, SASS (South African scoring system) netting, eDNA sampling and analysis where electrofishing may not be possible.

Method step description:

1. Sampling design for data collection 1. Electrofishing method and barcoding for freshwater fish survey Electrofishing Electrofishing will be led by Gaea Seychelles and experts from MNHN. A generator (Dekka Lord 2000) will be used for the sampling of freshwater fishes. The portable machine that was used had a battery with an output power of 180 W. It gives rectangular impulses at a fixed frequency of 100 Hz or 400 Hz. The duty cycle is controllable and is of 5 to 25 %. It has three voltage outputs: 150, 200 and 300 V. Electric fishing is performed in wadable streams by progressing in an upstream direction; in that way the water stays clear in front of the operators. The method (non-lethal) consists in placing a fishing electrode near habitat shelters in which the animals are found; the electrode creates an electrical field, which has an attraction effect within a radius of a one-meter zone under average conditions. When a fish comes within this field, it is stunned; it can then be caught easily with a hand net. Snorkeling with mask and hand nets will be also used, if possible, as a complementary method to the electrofishing. Each species caught is identified on the field and released. To constitute DNA barcoding reference libraries a piece of fin will be taken while the fish will be anaesthetised (the fish is awakened in clear water before it is released). Fin clips will be stored and preserved in 95% ethanol for molecular analysis (partial COI gene). DNA analysis for freshwater fish Barcoding for fish will be done by MNHN. The adoption of Next-Generation Sequencing (NGS) by the field of DNA barcoding of Metazoa has been hindered by the fit between the classical COI barcode and the Sanger-based sequencing method. The method used is described in the paper Hinsinger et al. 2015: a framework for the sequencing and multiplexing of mitogenomes on NGS platforms that implements (I) a universal long-range PCR-based amplification technique, (II) a two-level multiplexing approach (i.e. divergence-based and specific tag indexing), and (III) a dedicated demultiplexing and assembling script from an Ion Torrent (now we use an Illumina) sequencing platform. Hinsinger et al. 2015 provides a case study of mitogenomes obtained for two vouchered individuals of fishes and show that this workflow enables to recover over 100 mitogenomes per sequencing chip on a PGM sequencer. Molecular reference libraries: towards a global biodiversity information system for species identifications The MNHN build since several years’ molecular reference libraries for freshwater fish living in Indo-Pacific islands and particularly in Indian Ocean, establishing lists of taxonomically valid species. The use of eDNA and COI barcoding relies necessary on the development of DNA barcode reference libraries for known species in order to foster automated assignment of unknown specimens to known species. For automation purposes, both stability of the reference libraries and reproducibility of the molecular identifications should be guaranteed. That’s why MNHN build these libraries studying and sequencing (when possible) types specimens of each species. The libraries have already the sequences of the gene needed for several species distributed in Seychelles. 2. Micro and macro-invertebrate sampling lankton net method: Plankton nets of 80, 125 and 200 mesh size were used in this research. Mesh size is an aperture or eye size in net. Sample are collected through two methods that is horizontal tow and vertical tow. One need to enter in water through boat trawler to collect water sample. The handling of plankton nets from margin has possibility of damage and clogging. The surface water sample is collected through horizontal tow by tying floaters on end of the ring and heavy material at other end of the ring. Volume of water that flow through net can be calculated by formula as mentioned below. lankton net method: Plankton nets of 80, 125 and 200 mesh size were used in this research. Mesh size is an aperture or eye size in net. Sample are collected through two methods that is horizontal tow and vertical tow. One need to enter in water through boat trawler to collect water sample. The handling of plankton nets from margin has possibility of damage and clogging. The surface water sample is collected through horizontal tow by tying floaters on end of the ring and heavy material at other end of the ring. Volume of water that flow through net can be calculated by formula as mentioned below. Plankton net method: Plankton nets of 80, 125 and 200 mesh size were used in this research. Mesh size is an aperture or eye size in net. Sample are collected through two methods that is horizontal tow and vertical tow. One need to enter in water through boat trawler to collect water sample. The handling of plankton nets from margin has possibility of damage and clogging. The surface water sample is collected through horizontal tow by tying floaters on end of the ring and heavy material at other end of the ring. Volume of water that flow through net can be calculated by formula as mentioned below. Micro and macro-invertebrates sampling and identification will be done in conjuction with our expert partner GroundTruth (South Africa). Micro and macro-invertebrates will be collected using the methods described in the South African Scoring System version 5 (SASS5, Dickens and Graham 2002 ), a rapid kick sampling technique designed for wadable rivers that is ISO 17025 accredited. Kick samples are collected from three major biotopes 1) Stones (2cm – 25cm and includes bedrock sheets) in and out of current, 2) marginal and aquatic vegetation in and out of current and 3) gravel, sand and mud. Each biotope is sampled for a specific time or area as per the SASS5 method and macro-invertebrates from each biotope are identified to a family level. Each family is prescribed a sensitivity score from 1 to 15 depending on the water quality requirements for the family. Based on the sum and averages scores per taxon an aquatic ecological condition is generated for the river. MiniSASS is a citizen science version of the SASS5 method (Graham, et al. 2004 ). For miniSASS, the combined biotopes are sampled for approximately 10 mins and a combined sample is identified down to an order level. Each order has been assigned a sensitivity rating depending on the average water quality requirements of the Order and the average score per Order is used to determine the river condition. Plankton nets will be used to horizontally sweep through the water to collect zooplankton in the 15 rivers. The net will be rinsed to wash its content into the storage tube. The Zooplankton will be identified using a microscope in the lab.

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