1South African Institute for Aquatic Biodiversity (SAIAB) – Private Bag 1015 Grahamstown, 6140 South Africa, South Africa
2Marine Fisheries Research and Development Center Fisheries Research Agency (JAMARC) – 15F Queen’s Tower B, 2-3-3 Minatomirai, Nishi-ku, Yokohama, Kanagawa 220-6115, Japan
3 Branch Fisheries, Department of Agriculture, Forestry and Fisheries (DAFF) – Private Bag X2, Roggebaai 8012, South Africa
4 Department of Ecology, Evolution and Behavior (HUJ) – The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
5 Tel Aviv University [Tel Aviv] – P.O. Box 39040, Tel Aviv 6997801, Israel
6 Department of Zoology – Tel Aviv University 69978 Tel Aviv, Israel, Israel
7 Department of Biology, National Institute of Oceanography – Israel Oceanographic and Limnological Research, Tel Shikmona 8030, Haifa 31080, Israel
This presentation reports on research on species of three deeper water genera:
1. A taxonomic review ofEpigonus in the Western Indian Ocean (WIO) is currently under way.
Twelve species have been found. The finding of E. pectinifer in the southwest Indian Ocean extends its range to all three major oceans. It can be distinguished from other members of the genus in the WIO in having a slender tooth patch on the posterior part of the tongue. Two new species, from South Africa and Madagascar, have been discovered, both of the Epigonus constanciae species group. One new species differs from all other members of this group in having 4-5 small projections at lower jaw symphysis. The second is distinguished from the rest of its group by the presence of two spines on lower jaw symphysis; it differs from the first new species in having fewer pectoral fin rays and a different scale type.
2. The Catalogue of Fishes lists three valid Macruronus species. Of these M. maderensis and M. capensis have uncertain status. Macruronus capensis was described from a single specimen collected in 1950 in South Africa. Only a few specimens were captured since then, suggesting that this species is not established in South Africa. A comparative study using genetics and morphology found it to be identical to and therefore a junior synonym ofM. novaezelandiae.
3. Three species of Champsodon, assumed to be Lessepsian migrants from the Red Sea, have been reported from the Eastern Mediterranean in recent years. Of these, the presence in the Red Sea of only one species has been confirmed. The difficulties in identifying species of this genus are discussed in the context of an ongoing study to resolve these issues using morphology and molecular genetics.
∗Speaker
†Corresponding author: O.Gon@saiab.ac.za
The exceptional visual solution of the pearlsides (Sternoptychidae) to optimize
vision in twilight conditions.
Fanny De Busserolles ∗† 1,2, Fabio Cortesi 1, Jon Vidar Helvik 3, Wayne Davies 4, Rachel Templin 1, Robert Sullivan 1, Craig Michell 2, Jessica
Mountford 4, Shaun Collin 4, Xabier Irigoien 2,5, Stein Kaartvedt 2,6, Justin Marshall 1
1 Queensland Brain Institute, The University of Queensland – St Lucia, QLD 4072, Australia
2 King Abdullah University of Science and Technology – Thuwal, 23955-6900, Saudi Arabia
3University of Bergen – Bergen 5020, Norway
4University of Western Australia – Crawley, WA 6009, Australia
5 IKERBASQUE, Basque Foundation for Science; Bilbao – Spain
6 University of Oslo – Oslo, 0316, Norway
Most vertebrates have a duplex retina comprising two photoreceptor types, rods for dim- light (scotopic) vision, and cones for bright-light (photopic) and color vision. Deep-sea fishes, however, are only active in dim-light conditions hence, most species have lost their cones in favor of a simplex retina composed exclusively of rods. While pearlsides, Maurolicus spp., appear to possess such a pure rod retina, their behavior is at odd with this simplex visual system. Contrary to other deep-sea fishes, pearlsides are mostly active during dusk and dawn close to the surface, where light levels are intermediate (twilight or mesopic) and require the use of both rods and cone photoreceptors. To explore this paradox, we investigated the visual system of two species of pearlsides,Maurolicus muelleri from the Norwegian fjords andM. mucronatus from the Red Sea. Using a multidisciplinary approach including transcriptomics, in situ hybridization, in vitro regeneration, immunohistochemistry, retinal mapping and microscopy, this study shows that pearlsides have evolved an unconventional visual system to optimize visual performance in twilight conditions. Their previously categorized all-rod retina is in fact composed almost exclusively of transmuted cone photoreceptors. In other words, the pearlside does not possess the usual rods and/or cones, like most animals, but instead possess a third and more efficient type of photoreceptor that combines properties of both rods and cones. In more details, these transmuted cells combine the morphological characteristics of a rod photoreceptor with a cone opsin and a cone phototransduction cascade to form a unique photoreceptor type, a rod-like cone, specifically tuned to the light conditions of the pearlsides’ habitat (blue-shifted light at mesopic intensities). Combining properties of both rods and cones into a single cell type instead
duplex retina and its evolution, and call for more comprehensive evaluations of visual systems in general.
F1/ Causes and consequences of change for macroalgae-associated
fishes
Algal herbivory dynamics of fish across habitats in a shallow tropical seascape