SCYPHOMEDUSAE PHENOLOGY AND ABUNDANCE IN BOKA KOTORSKA BAY (SOUTHERN ADRIATIC) FROM 2013 TO 2017

Branka Pestoric 1*, Davor Lucic 2, Ivana Violic 2, Dragana Drakulovic 1 and Ivona Milic-Beran 2 1 Institute of Marine Biology University of Montenegro - [email protected] 2 University of Dubrovnik, Institute for Marine and Coastal Research, Croatia

Abstract Six species of Scyphomedusae were recorded in Boka Kotorska Bay from 2013 to 2017: Chrysaora hysoscella, spp., Discomedusa lobata, Cothyloriza tuberculata, Rhizostoma pulmo and Drymonema dalmatinum. Among them, C. hysoscella, D. lobata and C. tuberculata formed blooms.

Keywords: Blooms, South Adriatic Sea, Medusae

Introduction C. hysoscella, which is fed on other jellyfish. Higher number of Aurelia specimens was recorded at the end of May 2015, only (Table 2). Rhizostoma In Boka Kotorska Bay, there is still lack of information for gelatinous pulmo was irregularly observed in the Bay with a higher abundance only in carnivores despite of the long tradition of zooplankton investigations [1]. After August 2017. Rare species Drymonema dalmatinum recently become 2013, changes in scyphomedusan composition, phenology and abundance were increasingly common in the whole coast of the eastern Adriatic [4]. It was noticed throughout the Bay. Herein, we present the results of these new always recorded with low specimens number. In the Bay, species was found in observed events. June and August of 2014, and from April to June 2017, which is the longest known permanent observation of this species in one area.

Material and Methods Tab. 2. Appearance of non bloom forming Scyphomedusae in period 2013- 2017 in Boka Kotorska Bay (1- one specimen; 2- several specimens) Continuous monitoring of the Scyphomedusae occurrence in Boka Kotorska Bay started in 2013, after the first mass occurrence of some species. Monitoring was conducted by visual observations of scientists from the Institute of Marine Biology (Kotor, Montenegro) from the shore, and during diving. Additional information’s were reliable sources on the basis of reports through the actions of "Citizen Science".

Results and discussion

After the first record of specimen of Chrysaora hysoscella in Boka Kotorska Bay in 2006 [2], from 2014 this species were regularly present (Table 1). Especially extended bloom of 14 days was established in 2015. Discomedusa lobata is a rare Schyphomedusae and has been common in the Gulf of Trieste References until 1980s, only [3]. The reliable record in the Bay date from 2013 when 1 - Pestoric, B. D. Drakulovic, M. Hure, B. Gangai Zovko, I. Onofri, P. Lucic, specimens were found sporadically (Table 1). The first bloom, estimated at D. Lucic. 2016. Zooplankton Community in the Boka Kotorska Bay In: A. 100 individuals per 10 m2, was noted in April 2014, with another in mid-May. Joksimovic et al. (eds.), The Boka Kotorska Bay Environment. Hdb. Env. The latest bloom lasted two days, after which no individuals were observed. Chem., 54: 231-270. Springer International Publishing Switzerland, DOI Higher numbers (10 ind. per 10 m2) also were present for over eight days in 10.1007/698_2016_35. February 2015, after which individuals were found only sporadically. An 2 - Avian, M. 1992. Occurrence of Discomedusa lobate (: ) extremely dense bloom at the end of March 2015 occurred in a shallow part of in the Adriatic with notes on morphology. Oebalia, 17: 271-274. the Bay that is influenced by spring water. Water temperature during blooms 3 - Vukanic, V. 2006. Note of appearance of schyphomedusa Chrysaora ranged from 13.5°C to 19.1°C. Salinity generally was low, ranging between 8.5 hysoscella (Linne, 1766) at Bay of Kotor. Natura Montenegrina, 5: 49-53. and 25.5. Cothyloriza tuberculata was occasionally observed in the Bay from 4 - Malej, A. M. Vodopivec, D. Lucic,I. Onofri, B. Pestoric. 2014. The lesser- August to September (Table 1). The bloom was established only in 2017. known medusa Drymonema damatinum Haeckel 1880 (Scyphozoa, There was no information for C. tuberculata mass appearance in the Bay ) in the Adriatic Sea. Annales Ser. Hist. Nat., 24: 79-86. before. Aurelia specimens were less numerous.

Tab. 1. Appearance of bloom forming Scyphomedusae in period 2013-2017 in Boka Kotorska Bay (1- one specimen; 2- several specimens; 3- bloom)

According to personal communication of residents, frequency and abundance of this genus were higher in the past. It can be due to direct competition with

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