Sighting demographics of the West Indian manatee Trichechus manatus in the north-central Gulf of Mexico supported by citizen-sourced data

EE Hieb,RH Carmichael,C Nelson‑Seely,A Aven,N Taylor

doi:10.3354/esr00817

Abstract

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 32:321-332 (2017) - DOI: https://doi.org/10.3354/esr00817 Sighting demographics of the West Indian manatee Trichechus manatus in the north-central Gulf of Mexico supported by citizen-sourced data Elizabeth E. Hieb1,*, Ruth H. Carmichael1,2, Allen Aven1,2, Courtney Nelson-Seely1, Nicole Taylor1 1Dauphin Island Sea Lab, Dauphin Island, Alabama 36528, USA 2University of South Alabama, Mobile, Alabama 36688, USA *Corresponding author: ehieb@disl.org ABSTRACT: Traditional research methods are often limited in their ability to capture broad spatial and temporal changes in species distribution that affect global patterns of biodiversity. To provide range-wide demographic data needed to quantify and evaluate changes in habitat use and support ongoing recovery efforts for the endangered West Indian manatee Trichechus manatus, we analyzed data from a formal manatee sighting network that uses citizen-sourced data for the understudied north-central Gulf of Mexico region. Although historically considered to be outside manatees’ typical US range, more than 1700 opportunistic, publicly reported manatee sightings and 23 mortalities have been documented in Alabama and Mississippi since the early 1900s. Live manatee sightings have occurred primarily during warmer months in rivers and subembayments. Manatee mortalities have significantly increased since the mid-1980s and have most often been attributed to cold stress, with 2 known mortalities due to vessel strikes in recent years. Sightings of individual manatees were most common, but group sizes of up to 17 were reported, typically in late summer. Decadal-scale trends in opportunistic sighting records demonstrate persistent spatial and temporal patterns of manatee occurrence in the north-central Gulf of Mexico and suggest greater use and importance of the region as seasonal manatee habitat than previously documented. If applied appropriately, citizen-sourced data have the potential to enhance targeted research efforts, significantly contribute to ecological datasets for a number of species, and provide a useful tool to enhance conservation and management. KEY WORDS: Manatee · Gulf of Mexico · Distribution · Citizen science · Opportunistic data Full text in pdf format Supplementary material PreviousNextCite this article as: Hieb EE, Carmichael RH, Aven A, Nelson‑Seely C, Taylor N (2017) Sighting demographics of the West Indian manatee Trichechus manatus in the north-central Gulf of Mexico supported by citizen-sourced data. Endang Species Res 32:321-332. https://doi.org/10.3354/esr00817 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 32. Online publication date: April 07, 2017 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2017 Inter-Research.

Highlights

Shifts in species distribution and range can lead to long-term and widespread changes in species composition and food web linkages that alter biodiversity and coastal ecology (Walther et al 2002, Bellard et al 2012, Pimm et al 2014)
We evaluated the effectiveness of our citizen-sourced data collection methods to provide accurate data on manatee occurrence in the study region
To detect and account for potential bias in public reporting of manatee sightings, we examined the effect of public education and outreach activities on the number and timing of reported sightings

Summary

Introduction

Shifts in species distribution and range can lead to long-term and widespread changes in species composition and food web linkages that alter biodiversity and coastal ecology (Walther et al 2002, Bellard et al 2012, Pimm et al 2014). On the US northern Gulf of Mexico coast, sightings of the endangered West Indian manatee have increased in number and into colder months (Fertl et al 2005, Pabody et al 2009, Heck et al 2015, Aven et al doi:10.7287/peerj.preprints.2072v1). This increase in sightings has corresponded with increased seasonal mean water temperatures in the northern Gulf of Mexico region (Fodrie et al 2010) and manatee population growth in Florida during the past several decades Following catastrophic anthropogenic or natural disasters, occupancy and abundance data on affected species are critical to define damages, assess recovery, and guide decision-makers on strategic interventions to reduce negative impacts and support conservation (Machlis & McNutt 2010, Martin et al 2014)

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