Saturday, April 3, 2021

[Ichthyology • 2021] Blackwater Diving: An Exciting Window Into the Planktonic Arena and Its Potential to Enhance the Quality of Larval Fish Collections

Images of live larvae of:
(A) Eustomias, USNM 447021, 30 mm. (B) Aristostomias, USNM 447051, 24 mm. 
(C) Phtheirichthys lineatus, USNM 447055, 17 mm. (D) Ariosoma fasciatum, USNM 446991, 35 mm.

(A) Himantolophus albinares, USNM 447045, 4 mm. (B) Gigantactis vanhoeffeni, USNM 447056, 7 mm.
(C) Melanocetus johnsonii, USNM 447048, 5 mm. (D) Pseudogramma brederi, USNM 446998, 9 mm.

(A) Eutaeniophorus, USNM 447049, 44 mm (with head close-up image). (B) Malacosarcus macrostoma, USNM 447046, 13 mm. 
(C) Luciobrotula, USNM 447052, 24 mm. (D) Bathymicrops cf. regis, USNM 447054, 19 mm.

in Nonaka, Milisen, et al., 2021. 

“Blackwater diving,” or nighttime SCUBA diving in epipelagic environments, has become highly popular in recent years because lay participants encounter animals that are difficult and expensive to observe through other methods. These same observations can be priceless for researchers working with these species, so an interface between the scientific communities and recreational divers would be mutually beneficial. In this paper, we describe one such interface through the photography, collection, and DNA barcoding of larval fishes from the island of Hawaii. The images and videos from this activity provide an exciting window into the epipelagic environment and the way larval fishes appear and swim within it. Blackwater diving allows us to see the often-elaborate appendages and other specializations of these larvae as they appear in situ, prior to extensive net and fixation damage. However, blackwater diving remains an almost exclusively recreational pursuit, particularly popular among underwater photographers, who have little interest in (or object to) collecting specimens for scientists. Nonetheless, a logical next step is careful hand collection of specimens for scientific study. Growing numbers of recreational divers around the world have access to an otherwise expensive-to-research habitat. Here we present, for the first time, in situ and post-fixation photos of larval fishes that were hand collected and fixed in 95% ethanol by blackwater divers operating out of Kona, Hawaii, with DNA barcode identifications congruent with morphology and pigmentation where possible. With the right motivation, blackwater diving could augment research in the pelagic ocean and significantly enhance natural history collections and our knowledge of the larvae of marine fishes.


Images of live (left column) and fixed (right column) larvae of:
 (A) Eustomias, USNM 447021, 30 mm.
(B) Aristostomias, USNM 447051, 24 mm.
(C) Phtheirichthys lineatus, USNM 447055, 17 mm.
(D) Ariosoma fasciatum, USNM 446991, 35 mm.

Images of live (left column) and fixed (right column) larvae of:
(A) Eutaeniophorus, USNM 447049, 44 mm (with head close-up image).
(B) Malacosarcus macrostoma, USNM 447046, 13 mm.
(C) Luciobrotula, USNM 447052, 24 mm.
(D) Bathymicrops cf. regis, USNM 447054, 19 mm.

Ai Nonaka, Jeffrey W. Milisen, Bruce C. Mundy and G. David Johnson. 2021. Blackwater Diving: An Exciting Window Into the Planktonic Arena and Its Potential to Enhance the Quality of Larval Fish Collections. Ichthyology & Herpetology. 109(1); 138-156. DOI: 10.1643/i2019318