Scyphozoa Pelagia noctiluca (Forsskal, 1775): blooming on the coast of Gujarat, India and its predation by Anemonia viridis (Forsskal, 1775)

The jellyfish bloom, i.e. the aggregation of Pelagia noctiluca, which occurred in January 2016 along the Shivrajpur coast facing the Arabian Sea, is reported. The jellyfish population was studied based on the Pelagia noctiluca individuals that were stranded in low tide pools and those that were washed ashore. Transects were laid to collect data on the jellyfish density. The oceanographic and physicochemical parameters at the time of bloom were studied. The probability of correlation between the time of bloom and the movement of P. noctiluca was considered. Additionally, mating and predation on the species were documented. We assume that the jellyfish bloom might have drifted to this coast due to the landlocked characteristics of the Arabian Sea and northward movements of sea currents. So far, jellyfish has been known to be the dietary preference of several vertebrate predators. Here, we report an interesting event of Anemonia viridis feeding on Pelagia noctiluca during their blooms in several intertidal pools on the coast.

Parasite community of a temporal notothen fish from intertidal rocky pools in south-central Chile: Is it similar to other fish from the same habitat?

Notothen fishes (Nototheniidae) have been recorded on the coasts of South America, from 35°S to southern. Little is known about the biology of intertidal notothen fishes or their relationships with other species, including parasites. Here, we analyzed the parasitic fauna of a species of Notothenia collected from the rocky intertidal of Lebu, south-central Chile (36°S) and compared the parasite community of this host with other 9 fish species commonly found in rocky intertidal pools. Among the tested species, Notothenia sp. had the highest parasite richness (21 parasitic taxa vs. 1 to 9 parasitic taxa). The composition of parasite species was different among fishes, with similarity indices between 0 and 33%. The parasite composition of Notothenia sp. was most similar to Calliclinus geniguttatus (27%). The most abundant and prevalent parasites found in Notothenia sp. were the copepod Caligus cf. cheilodactyli, Tetraphyllidea larvae, anisakid nematodes, and several acanthocephalan species, which are typical of other fish from the subtidal and bento-demersal zones. Therefore, we conclude that the juveniles of Notothenia sp. were a few months old and had their parasites when reaching the intertidal zone, acquired some generalist parasites during their stay in this habitat, such as Holobomolochus chilensis and Lecithaster macrocotyle. Most notothen fishes are from Antarctic and Sub-Antarctic waters, therefore, it is possible that this fish came from another habitat but also from the austral region of South America. Notothenia sp. could not be specifically identified because of different results between morphological and genetic analyses.

Photobiology of the zoanthid Zoanthus sociatus in intertidal and subtidal habitats

Intertidal environments are boundaries between marine and terrestrial ecosystems that are subject to rapid fluctuations across tidal cycles. This study investigates, for the first time, the photobiology of symbiotic zoanthids inhabiting different tidal environments: subtidal, intertidal pools and intertidal areas exposed to air during low tide. More specifically, we assessed the photochemical efficiency, Symbiodinium density and photosynthetic pigments profile of Zoanthus sociatus during low tide. Photochemical efficiency was lower and cell density higher in air exposed zoanthids. The profile of photosynthetic pigments also varied significantly among tidal habitats, particularly photoprotective pigments such as dinoxanthin and diadinoxanthin. Differences were also observed for the pigment content per cell, but the proportion of particular pigments (peridinin/chlorophyll-a and diatoxanthin+diadinoxanthin/chlorophyll-a) remained stable. Results suggest that aerial exposure conditions induce reversible downregulation of photochemical processes but no photophysiological impairment or bleaching. These findings provide a baseline for future studies addressing the prevalence of these overlooked cnidarians in environmentally dynamic reef flats.