The Importance of Stealth: Recent Findings with the Eye-in-the-Sea Deep-Sea Observatory

The Eye-in-the-Sea (EITS) observatory was designed to be acoustically quiet and to use far-red illumination to observe deep-sea animals unobtrusively. The EITS has clearly demonstrated the critical importance of stealth in research ocean observatories. Its use has revealed both animals and behaviors never seen before. Additionally recordings of animal activity under different lighting conditions and in the presence or absence of different sound-producing vehicles (ROVs and submersibles) have revealed to what extent tools for exploration bias observations. Recent recordings made during a 2007 NOAA Ocean Exploration mission to deep waters around the Bahamas provide excellent additional examples of the importance of stealth. During three 36 hr deployments, at 487, 548 and 694 m, at least nine species of deep-sea shark were recorded. A clear diurnal rhythm was apparent with smaller sharks such as Squalus cubensis seen during the day and larger sharks such as Hexanchus griseus at night. Examples of recordings made of unusual behaviors will be shown including bottom-rooting by six-gill sharks and different swimming behaviors of barracudinas (Paralepididae) under red light as compared to white light

Correlation Between Photosensitivity and Downwelling Irradiance in Mesopelagic Crustaceans

The current study determined behavioral and electrophysiological photosensitivities for three species of mesopelagic crustaceans: Pasiphaea multidentata Esmark, 1866 (Decapoda: Pasiphaeidae), Sergestes arcticus Kröyer, 1855 (Decapoda: Sergestidae), and Meganyctiphanes norvegica M. Sars, 1857 (Euphausiacea: Euphausiidae). In addition, in situ quantifications of the species’ vertical distributions in relation to downwelling irradiances were also determined in two locations in the northwest Atlantic Ocean, Wilkinson Basin (WB) and Oceanographer Canyon (OC). Data are from six 2-week cruises between June and September from 1995 to 2001. P. multidentata and M. norvegica were the most abundant large crustaceans in WB, and S. arcticus and M. norvegica were the most abundant large crustaceans in OC. The behavioral light sensitivity thresholds of P. multidentata and M. norvegica from WB were both 107 photons cm−2 s−1 and those of S. arcticus and M. norvegica from OC were both 108 photons cm−2 s−1. Electrophysiologically, P. multidentata was significantly more sensitive than M. norvegica from either location, S. arcticus was significantly more sensitive than M. norvegica from OC, and M. norvegica from WB was significantly more sensitive than M. norvegica from OC. A correlation was found between electrophysiologically measured photosensitivity and downwelling irradiance, with the most sensitive species, P. multidentata and S. arcticus, associated with the lowest irradiance at daytime depths. The photosensitivities of M. norvegicacollected from the clearer waters of OC were significantly lower than those of individuals collected from the more turbid WB waters. These results indicate that downwelling irradiance has a significant impact on interspecies and intraspecies vertical distribution patterns in the mesopelagic realm

Light and Vision in the Deep-Sea Benthos: I. Bioluminescence at 500-1000 m Depth in the Bahamian Islands

Bioluminescence is common and well studied in mesopelagic species. However, the extent of bioluminescence in benthic sites of similar depths is far less studied, although the relatively large eyes of benthic fish, crustaceans and cephalopods at bathyal depths suggest the presence of significant biogenic light. Using the Johnson-Sea-Link submersible, we collected numerous species of cnidarians, echinoderms, crustaceans, cephalopods and sponges, as well as one annelid from three sites in the northern Bahamas (500–1000 m depth). Using mechanical and chemical stimulation, we tested the collected species for light emission, and photographed and measured the spectra of the emitted light. In addition, in situ intensified video and still photos were taken of different benthic habitats. Surprisingly, bioluminescence in benthic animals at these sites was far less common than in mesopelagic animals from similar depths, with less than 20% of the collected species emitting light. Bioluminescent taxa comprised two species of anemone (Actinaria), a new genus and species of flabellate Parazoanthidae (formerly Gerardia sp.) (Zoanthidea), three sea pens (Pennatulacea), three bamboo corals (Alcyonacea), the chrysogorgiid coral Chrysogorgia desbonni (Alcyonacea), the caridean shrimp Parapandalus sp. and Heterocarpus ensifer (Decapoda), two holothuroids (Elasipodida and Aspidochirota) and the ophiuroid Ophiochiton ternispinus (Ophiurida). Except for the ophiuroid and the two shrimp, which emitted blue light (peak wavelengths 470 and 455 nm), all the species produced greener light than that measured in most mesopelagic taxa, with the emissions of the pennatulaceans being strongly shifted towards longer wavelengths. In situ observations suggested that bioluminescence associated with these sites was due primarily to light emitted by bioluminescent planktonic species as they struck filter feeders that extended into the water column

Vision and Bioluminescence in the Deep-Sea Benthos

During a NOAA-OER funded research cruise, novel collecting techniques were used to collect live, deep-sea benthic animals for studies of bioluminescence and vision. True color images and emission spectra of bioluminescence were obtained from a number of species, including the spiral octocoral Iridogorgia sp., the sea fan Chrysogorgia sp., the sea pen Umbellula sp., and the caridean shrimp Heterocarpusoryx. Electrophysiological studies were conducted on 3 species of decapod crustaceans collected with methods that limited light damage to their photoreceptors. The caridean shrimp, Bathypalaemonella, collected from 1920m, was always found in association with the bioluminescent spiral octocoral Iridogorgia. While moribund at the surface, enough data were obtained from one specimen to show different wave forms in response to short and long wavelength light, indicative of two different classes of photoreceptor cells. The chirostylid crab, Uroptychusnitidus, found in association with the bioluminescent sea fan, Chrysogorgia sp., also appears to possess two visual pigments, and if further analysis of data supports this preliminary observation, will be the 4th species of deep-sea, non-bioluminescent crustaceans possessing two visual pigments found in association with bioluminescent cnidarians. These four species also share another characteristic–the presence of one or two very long claws, which the crab species are known to use to pick items (possibly plankton stuck in the mucus) off their cnidarian hosts. These data support the previously presented hypothesis (Frank et al. 2012), that these crustaceans may be utilizing their dual visual pigment systems to distinguish between prey and host, based on spectral differences between pelagic and benthic bioluminescence.

Transparency and Visibility of Gelatinous Zooplankton from the Northwestern Atlantic and Gulf of Mexico

Volume: 195Start Page: 337End Page: 34

Evidence for Behavioral Sensitivity to Near-UV Light in the Deep-Sea Crustacean Systellaspis debilis

The role of UV light in the deep-sea environment has been discounted in the past, due to the assumptions that (1) there is insufficient UV light available for vision and, therefore (2) deep-sea organisms would not be sensitive to these wavelengths. A recent study that employed electrophysiological techniques on dark-captured deep-sea crustaceans demonstrated that several species of deep-sea crustaceans possess very high sensitivity to near-UV light. The current study was undertaken to determine if near-UV light would also elicit a behavioral response from these species. The species studied was Systellaspis debilis, an oplophorid shrimp whose daytime depth ranges from 600 to 700 m. A method for tethering shrimp was developed which allowed them to freely orient in response to changes in the ambient light field. Behavioral responses to changes in ambient light included changes in body tilt with respect to the horizontal plane, changes in swimming speed, and movement of the feeding appendages. These experiments, the first of their kind on a deep-sea organism, demonstrate that behaviorally, S. debilis is equally sensitive to very low intensities of blue-green and near-UV light

UV Light in the Deep Sea: In situ Measurements of Downwelling Irradiance in Relation to the Visual Threshold Sensitivity of UV-Sensitive Crustaceans

Combining behavioural and psychological approaches to the study of plankton on present and interdisciplinary investigation of sensory processes in pelagic environments, this text provides insights into the larger scale ecological processes of biological productivity, community structure and population dynamics.https://nsuworks.nova.edu/occ_facbooks/1047/thumbnail.jp

DISTRIBUTION OF SUBCELLULAR BIOLUMINESCENT SOURCES IN A DINOFLAGELLATE, PYROCYSTIS FUSIFORMIS

Volume: 162Start Page: 423End Page: 44