Drifter or homebody? Study first to show where whitespotted eagle rays roam

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Breanna DeGroot, M.S., and Matt Ajemian, Ph.D., FAU Harbor Branch, pictured with a whitespotted eagle ray. Credit: Mike McCallister, FAU Harbor Branch

Its muscular physique form and enormous pectoral fins are good for long-distance journey, but motion patterns of the whitespotted eagle ray (Aetobatus narinari) stay a thriller. Researchers from Florida Atlantic University’s Harbor Branch Oceanographic Institute in collaboration with Mote Marine Laboratory & Aquarium, the University of Florida and the Florida Fish and Wildlife Conservation Commission, are the first to conduct a multiyear examine inspecting large-scale actions of whitespotted eagle rays in United States waters.

Between 2016 and 2018, scientists fitted 54 rays with acoustic transmitters and tracked them utilizing collaborative acoustic telemetry networks. The rays have been tagged alongside each the Gulf of Mexico and Atlantic coasts of Florida, which differ in environmental traits. Scientists in contrast rays’ motion patterns between the Atlantic and Gulf coasts and gathered knowledge on migratory routes, seasonality and habitat use. Their findings counsel that potential sub-population structuring could also be occurring inside Florida greater than beforehand thought and have vital conservation and adaptive administration implications for this protected species.

Results of the examine, printed within the journal Marine Biology, reveal putting variations in journey patterns on the Atlantic coast in contrast to the Gulf coast. The majority of Gulf coast whitespotted eagle rays most popular to “spread their wings,” exhibiting migratory and transient behaviors, whereas most Atlantic coast tagged rays have been “homebodies” and remained a resident throughout the Indian River Lagoon. Atlantic coast rays spent higher than 5 instances the period of time inshore, no matter maturity or intercourse, than Gulf coast rays.

“Although tagged at similar latitudes, whitespotted eagle rays exhibited coastline-specific movements. The rays on the Gulf coast conduct repetitive annual migration patterns, heading south from Sarasota starting in fall and returning to the area in early spring,” stated Breanna DeGroot, M.S., first writer and analysis coordinator, FAU Harbor Branch.

DeGroot labored on the examine with co-author Matt Ajemian, Ph.D., principal investigator, an assistant analysis professor at FAU Harbor Branch and head of the Fisheries Ecology and Conservation (FEC) Lab, who supervised the examine.

Drifter or homebody? Study first to show where whitespotted eagle rays roam
A whitespotted eagle ray (Aetobatus narinari). Credit: Kim Bassos-Hull

“This behavior is likely driven by a combination of environmental factors, but most notably temperature. In addition, the expansive, shallow shelf on the Gulf coast may provide additional habitat, enabling rays to move over larger distances along nearshore migratory corridors and lessen their reliance on inshore estuaries,” stated Ajemian.

On each coastlines, water temperatures throughout instances when rays have been current have been considerably hotter (no less than 27.8 levels Celsius) in contrast to temperatures when rays have been absent (beneath 24.9 levels Celsius), suggesting it might be a serious abiotic issue influencing migration patterns. Ontogenetic shifts in habitat use have been evident alongside the Atlantic coast within the Indian River Lagoon, however not alongside the Gulf coast. Immature rays spent considerably extra time (about 91.5 %) contained in the Indian River Lagoon in contrast to mature counterparts (about 60.2 %).

“Most of the rays we tagged on Florida’s Atlantic coast resided in the same area where they were originally tagged, which increases their susceptibility to local stressors like persistent environmental impacts in the Indian River Lagoon,” stated DeGroot. “Moreover, immature rays spent a significantly larger proportion of time inside the confines of the lagoon. This is especially disconcerting because we found no evidence of neonate or young-of-the-year rays leaving the lagoon throughout the entire three-year study.”

The constant presence of rays within the Indian River Lagoon all through the examine means that it serves as parturition grounds and nursery habitat for rays. As men and women have been equally resident to the Sebastian portion of the Indian River Lagoon, this space is probably going an essential feeding floor, nursery habitat, mating location, pupping floor, or serves a mix of those roles.

“This information about year-round or seasonal residency and longer distance migrations would not be possible without the collaborative data sharing of the acoustic telemetry networks such as iTAG and the FACT Network,” stated Kim Bassos-Hull, M.Sc., co-author and senior biologist with Mote Marine Lab’s Sharks & Rays Conservation Research Program.







An Atlantic coast eagle ray in Florida’s Indian River Lagoon. Atlantic coast rays spent higher than 5 instances the period of time inshore, no matter maturity or intercourse, than Gulf coast rays. The rays on the Gulf coast conduct repetitive annual migration patterns, heading south from Sarasota beginning in fall and returning to the realm in early spring. Credit: Cameron Luck

According to Ajemian, there’s a want for a greater understanding of how excessive climate occasions comparable to hurricanes and fluctuations in environmental elements comparable to crimson tide and dangerous algal blooms might impression ecologically essential large-bodied mesopredators just like the whitespotted eagle ray, as a result of the frequency of those occasions is predicted to improve but the potential alterations on the ecosystem stay unknown.

“This is a critical issue that requires increased tracking infrastructure and new analytical approaches,” stated Susan Lowerre-Barbieri, Ph.D., co-author, University of Florida and Florida Fish and Wildlife Conservation Commission, who led an iTAG workshop on this matter.

Study co-authors are Krystan A. Wilkinson, Ph.D., Mote Marine Lab’s Sharks & Rays Conservation Research Program and the Chicago Zoological Society’s Sarasota Dolphin Research Program; and Gregg R. Poulakis, Ph.D., Florida Fish and Wildlife Conservation Commission.

“I’m looking forward to adding more pieces to the eagle ray puzzle in the coming years as these animals get detected for years to come along both coasts of the state and beyond,” stated Poulakis.


Biotelemetry supplies distinctive glimpse into whitespotted eagle rays’ conduct


More data:
Breanna C. DeGroot et al, Variable migration patterns of whitespotted eagle rays Aetobatus narinari alongside Florida’s coastlines, Marine Biology (2021). DOI: 10.1007/s00227-021-03821-2

Provided by
Florida Atlantic University


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Drifter or homebody? Study first to show where whitespotted eagle rays roam (2021, February 23)
retrieved 23 February 2021
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