Distribution changes of plankton communities in the harbour Porto Montenegro (South Adriatic Sea)

Plankton data (phyto, zoo and ichthyo) that were collected monthly from March 2016 to February 2017 in the harbour ?Porto Montenegro? and the referent station (Tivat Bay) were analysed to determine if there are any differences in plankton distribution, composition and diversity among sites. In contrast to phytoplankton and zooplankton, whose diversity and spatial distribution are driven considerably by temperature and salinity (phytoplankton) and inter-species interaction, affinity for aggregation with specific water masses (zooplankton), the spatial dynamics of ichthyoplankton is significantly dependent on the aggregation of adult populations, rates of mortality, and physical processes that affect the position and retention of organisms. Anchovy early life stages and the dominance of this species in referent station during all months of investigation, especially in August, caused significant difference among sites. We found that unfavourable conditions for adult fish aggregation in the harbour area ?Porto Montenegro? could be the reason for driving the differences in the ichthyoplankton spatial distribution compared with Bay area, while phytoplankton and zooplankton data didn?t show significant differences among sites.Fil: Pestorić, Branka. University of Montenegro. Institute of Marine Biology; MontenegroFil: Drakulović, Dragana. University of Montenegro. Institute of Marine Biology; MontenegroFil: Mandić, Milica. University of Montenegro. Institute of Marine Biology; MontenegroFil: López Abbate, María Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin

Planktonski žarnjaci Boka-Kotorskog zaljeva, Crna Gora (južni Jadran)

Planktonic cnidarians were investigated at six stations in the Boka Kotorska Bay from March 2009 to June 2010 by vertical hauls of plankton net from bottom to surface. In total, 12 species of hydromedusae and six species of siphonophores were found. With the exception of the instant blooms of Obelia spp. (341 ind. m-3 in December), hydromedusae were generally less frequent and abundant: their average and median values rarely exceed 1 ind. m-3. On the contrary, siphonophores were both frequent and abundant. The most numerous were Muggiaea kochi, Muggiaea atlantica, and Sphaeronectes gracilis. Their total number was highest during the spring-summer period with a maximum of 38 ind. m-3 observed in May 2009 and April 2010. M. atlantica dominated in the more eutrophicated inner area, while M. kochi was more numerous in the outer area, highly influenced by open sea waters. This study confirms a shift of dominant species within the coastal calycophores in the Adriatic Sea observed from 1996: autochthonous M. kochi is progressively being replaced by allochthonous M. atlantica in the coastal waters, especially in the eutrophicated areas. This study provides a detailed report on the composition and abundance of the planktonic cnidarians community in this region, and should be considered as a baseline for future studies on gelatinous zooplankton.Istraživanje planktonskih žarnjaka obavljeno je na šest postaja Boka-kotorskog zaljeva od ožujka 2009. do lipnja 2010. Uzorci su sakupljeni vertikalnim potezima planktonske mreže od dna do površine. Ukupno je nađeno 12 vrsta hidromeduza i 6 vrsta sifonofora. S izuzetkom velikih nakupina vrste roda Obelia u prosincu 2009. (341 jed. m-3), prosječne vrijednosti hidromeduza rijetko su prelazile vrijednost od 1 jed. m-3. za razliku od hidromeduza, sifonofore su bile češće i brojnije, osobito u proljeće i ljeto. Najbrojnije su bile Muggiaea kochi, Muggiaea atlantica i Sphaeronectes gracilis. Najveća gustoća od 38 jed. m-3 utvrđena je u svibnju 2009 i ožujku 2010. godine. Vrsta M. atlantica je dominirala u eutroficiranom unutrašnjem dijelu zaljeva, dok je M. kochi bila brojnija u vanjskom dijelu zaljeva koji je pod jakim utjecajem otvorenog mora. Naša istraživanja su potvrdila dosadašnja saznanja za Jadransko more da u obalnim, osobito eutroficiranim područjima, novo pridošla sifonofora M. atlantica postaje dominatna u odnosu na autohtonu vrstu M. kochi. Ova istraživanja donose prve detaljne podatke o sastavu i brojnosti planktonskih žarnjaka Bokakotorskog zaljeva i predstavljaju osnovu za buduća istraživanja želatinoznog zooplanktona

Nalazi meduze Aequorea cf. forskalea u Jadranskom moru: usporedba povijesnih i recentnih podataka

Jellyfish are becoming an increasingly important component of studies of the global marine environment, as their frequent mass phenomena affect ecosystem performance and have economic and health consequences. Recent research has focused primarily on mass occurrences of scyphozoans and ctenophores, while less attention has been paid to hydromedusae blooms, which can also have significant impacts on the marine ecosystem with economic consequences. Like many members of the Scyphozoa and Ctenophora, Aequorea species can be numerous and form blooms. Based on surveys from 2000 to 2020 and information provided by marine professionals, we examine the (multiannual) variability, seasonality, and spatial distribution patterns of the poorly studied temperate species Aequorea cf. forskalea (Hydrozoa: Leptothecata). We hypothesized that this macrogelatinous jellyfish with a bipartite life cycle (benthic polyps and planktonic medusae) is sensitive to seasonal and long-term temperature fluctuations, particularly because temperature has been shown to play a critical role in mediating transitions in the life cycle of cnidarians. The cold-water affinity of A. cf. forskalea was confirmed by a significant negative correlation with temperature and the most frequent occurrence during the winter-spring period. For the northern Adriatic (Gulf of Trieste), sea temperature data and semi-quantitative plankton data are available for the first decade of the 20th century, allowing comparison of the historical data (1900-1911) with our current data set. Compared to historical records, the current occurrence of A. cf. forskalea differs significantly. With the warming of the northern Adriatic Sea since the beginning of the 20th century, the current phenology of A. cf. forskalea has changed, probably related to the delayed production of medusae by hydroids in autumn, the absence of medusae in this season and their less frequent occurrence in winter.Meduze postaju sve važnija komponenta globalnog proučavanja morskog okoliša, budući da njihove česte masovne pojave utječu na održanje ekosustava, a imaju ekonomske i zdravstvene posljedice. Najnovija su istraživanja usmjerena prvenstveno na masovnu pojavu režnjaka (Scyphozoa) i rebraša (Ctenophora), dok se manje pažnje posvećuje masovnim pojavama hidromeduza, koje također mogu imati veliki utjecaj na morski ekosustav sa značajnim ekonomskim posljedicama. Poput mnogih pripadnika Scyphozoa i Ctenophora, vrste roda Aequorea se mogu javljati u visokim brojnostima te njihovu pojavu možemo opisati kao masovnu („bloom“). Na temelju podataka prikupljenih tijekom istraživanja Jadrana u razdoblju od 2000. do 2020. godine te informacija dobivenih od stručnjaka koji se bave istraživanjem mora, razmatrali smo višegodišnju i sezonsku varijabilnost kao i obrasce prostorne raspodjele slabo proučavane vrste Aequorea cf. forskalea (Hydrozoa: Leptothecata) koja nastanjuje umjerena klimatska područja. Pretpostavili smo da je ova makro-želatinozna meduza, s bipartitnim životnim ciklusom (bentoski polipi i planktonske meduze), osjetljiva na sezonske i dugoročne promjene temperaturne, budući da temperatura igra ključnu ulogu za izmjenu generacija u životnom ciklusu žarnjaka (Cnidaria). Afinitet A. cf. forskalea prema hladnoj morskoj vodi potvrđuje značajna negativna korelacija s temperaturom te učestalo pojavljivanje tijekom zimsko-proljetnog razdoblja. Podaci o temperaturi mora i abundancijama vrste su dostupni za sjeverni Jadran (Tršćanski zaljev) za prvo desetljeće 20. stoljeća, što je omogućilo usporedbu povijesnih podataka (1900.-1911.) s novim setom podataka. U usporedbi s povijesnim zapisima, recentna se pojava A. cf. forskalea značajno razlikuje. Sa zatopljenjem sjevernog dijela Jadranskog mora od početka 20. stoljeća se mijenja sadašnja fenologija vrste A. cf. forskalea, što je vjerojatno povezano sa zakašnjelom proizvodnjom meduza u jesen, izostankom tijekom jeseni i njihovom rjeđom pojavom tijekom zime

Monitoring the eutrophication using Landsat 8 in the Boka Kotorska Bay

Ova studija predlaže metodologiju za nadgledanje koncentracija klorofila-a i eutrofičnog stanja u malim zalivima ili u blizini obale. Ova vrsta nadgledanja je zanimljiva jer uobičajena satelitska metodologija, bazirana na MODIS satelitu, nije funkcionalna u ovim oblastima zbog nedovoljne prostorne rezolucije senzora. U ovom radu je predstavljen pristup procjeni koncentracija klorofila-a baziran na Landsat 8 satelitskim snimcima i mjerenjima koncentracije obavljenim na određenim lokacijama na dan prelijetanja satelita. Dodatno, dva klasifikatora stanja (dnevni i godišnji) eutrofikacije, koji koriste određene koncentracije, su također prikazani. Preciznost predloženih metoda je procijenjena koristeći „leave-one-out“ unakrsnu validaciju, te rezultati pokazuju da je preciznost unutar teoretskih limita metoda baziranih na Ladsat 8 satelitu. Rezultati klasifikatora upoređeni su sa mjerenjima na terenu i pokazuju da je dnevni klasifikator u mogućnosti da klasificira oblast od interesa sa manje of 2% pogreški.This study proposes a methodology for monitoring concentrations of chlorophyll a (Chl-a) and the state of eutrophics in small bays or in the immediate vicinity of the coast. This kind of monitoring is of interest since such areas have not been addressed well using the usual satellite methods (such as MODIS) due to inadequate spatial resolution. We present an estimation approach for Chl-a concentration based on Landsat 8 (L8) satellite images using the ground truth (GT) data for the day of overflight. Additionally, two classifiers (daily and yearly) of the state of eutrophication, that use the Chl-a estimated values, are presented. The accuracy of the proposed method is evaluated using the leave-one-out cross validation, and it is within limits theoretically expected of an L8-based approach. The results from the classifiers are compared with the GT data and it is shown that daily classifier is able to classify the area of interest with an incidence of false positives less than 2%

Algal pigments distribution and phytoplankton group assemblages in the coastal transitional environment – Boka Kotorska Bay (Southeastern Adriatic Sea)

Prisutnost zajednica fitoplanktona i rasprostranjenost pigmenata utvrđivani su u tranzicijskim vodama Bokokotorskog zaljeva. Uzorci su prikupljeni četiri puta na tri lokaliteta u unutrašnjosti Zaljeva u periodu između travnja 2008. i ožujka 2009. godine. Mikroskopskom analizom utvrđeno je da fitoplankton čine morske dijatomeje, dinoflagelati, kriptofiti, klorofiti i kokolitoforidi. Pored fukoksantina kao dominantnog biomarkerskog pigmenta, bili su zastupljeni i aloksantin, 19′-heksanoiloksifukoksantin, peridinin i klorofil b‏. Fukoksantin i aloksantin su pokazali značajnu korelaciju sa klorofilom a kao indikatorom biomase fitoplanktona tijekom čitavog perioda ispitivanja. U studenom 2008. godine, dijatomeje su nadjačale kokolitoforide, koji su vjerovatno efikasno apsorbirali nutrijente tijekom perioda u kojem je njihova dostupnost bila smanjena. Kao rezultat smanjenog unosa nutrijenata, u ljetnom periodu, zajednicu fitoplanktona u Bokokotorskom zaljevu sačinjavali su uglavnom morski dinoflagelati, kriptofiti i klorofiti.Phytoplankton assemblages and pigment distribution were determined in the transitional Boka Kotorska Bay. Samples were collected four times from three stations in the inner part of the Bay between April 2008 and March 2009. Microscopic analysis revealed that the phytoplankton was composed of marine diatoms, dinoflagellates, cryptophytes, chlorophytes and coccolithophorids. Aside from fucoxanthin as the dominant biomarker pigment, alloxanthin, 19′-hexanoyloxyfucoxanthin, peridinin and chlorophyll b provided indicative contributions. Fucoxanthin and alloxanthin showed significant correlation with the phytoplankton chlorophyll a biomass throughout the investigated period. In November 2008, the diatoms were outcompeted by coccolithophorids, which probably efficiently absorbed nutrients during a period of their reduced supply. Due to the reduced nutrient input, in the summer, the phytoplankton community in the Bay was composed mostly of marine dinoflagellates, cryptophytes, and chlorophytes

Novonastale promjene (2013-2017) faune režnjaka u Bokokotorskom zaljevu, Crna Gora (jugoistočni Jadran)

A semi- quantitative time series (2013-2017) was used to present the recent events of scyphomedusae appearance and abundance in the Boka Kotorska Bay, Montenegro, Southeast Adriatic. Six meroplanktonic species were recorded: Aurelia spp, Chrysaora hysoscella, Cotylorhiza tuberculata ̧ Discomedusa lobata, Drymonema dalmatinum and Rhizostoma pulmo. Among them, C. hysoscella and D. lobata dominated in the water column during winter and spring, forming dense aggregations in March and May, and February to May, respectively. Our description of the D. lobata blooms are actually the first known records of blooms for this species. C. tuberculata was observed in the Bay principally in August and September. The bloom was occurred only in 2017, being the first information of C. tuberculata mass appearance in this area. We hypothesized that global warming phenomena could trigger the observed changes, and in this respect, long-term trends of sea surface temperature (SST) fluctuations were analysed. The scyphomedusae blooms coincided with high positive SST anomalies, noted in the last seven years for this area. To better understand the mechanisms underlying changes in their phenology and abundance, detailed studies on benthic stages in the Bay are essential.Semi kvantitativne serije podataka (2013.-2017.) upotrjebljene su za prikaz novonastalih promje-na pojave i brojnosti režnjaka u akvatoriju Bokokotorskog zaljeva. Pretpostavljajući da bi globalno zagrijavanje moglo potaknuti promatrane promjene, analizirani su dugoročni trendovi fluktuacija površinske temperature mora. Zabilježeno je šest meroplanktonskih vrsta: Aurelia spp, Chrysaora hysoscella, Cothyloriza tuberculata ̧ Discomedusa lobata, Drymonema dalmatinum i Rhizostomapulmo. Među njima C. hysoscella, i D. lobata su bile veoma česte i brojne., formirajući nakupine velikih gustoća tijekom zime i proljeća. Za vrstu D. lobata je ujedno prvi poznati opis masovne pojave ove meduze. Vrsta C. tuberculata je u akvatoriju bila primijećena tijekom ljeta, a u velikim gustoćama samo u 2017. godini. To je prvi dokumentirani opis masovne pojave ove meduze u Boko-kotorskom zaljevu. Pojave mase režnjaka u plankton podudaraju se s visokim odstupanjima površin-ske temperature mora zabilježenih posljednjih sedam godina. Stoga, naši opisi fenologije i brojnosti režnjaka u Bokokotorskom zaljevu su u skladu s dokazima porasta gustoće populacija želatinoznog zooplanktona na globalnoj skali. Za bolje razumijevanje mehanizma opisanih promjena neophodno je provesti detaljna istraživanja biologije i ekologije bentonskih stadija ovih organizama

Sastav i raspodjela zooplanktona duž obalnih i otvorenih voda Albanije (južni Jadran) u kasno proljeće

We present for the first time composition, numerical abundance and vertical structure of microand mesozooplankton in the Albanian coastal and open sea region. Zooplankton was sampled at six stations on the 75-km long continental shelf slope transect in May 2009. The most numerous microzooplankton were copepod nauplii (maximum: 39 ind. L-1), followed by calonoid and cyclopoid copepodites (maxima: 5 and 4 ind. L-1, respectively). The most abundant of fourteen tintinnid species was Tintinnopsis radix, found in the surface to 50 m layer. The species composition of the coastal and open sea mesozooplankton was similar to that previously reported for the south Adriatic Sea. The copepod Oithona similis was the dominant species at all stations, followed by Oithona plumifera, Acartia clausi, Paracalanus parvus, Oithona nana and cyclopoida-oncaeids at the shallower coastal stations, and Clausocalanus pergens, Oithona plumifera and Oithona nana offshore. Mesozooplankton diversity rose considerably from the coast to the open sea. Mesozooplankton abundance exhibited the opposite trend, with the maximum (2286 ind. m-3) noted at the shallowest station. Findings of typically open sea tintinnid and copepod species at the coastal station indicate the high influence of currents from the open sea area during our investigation. Our results suggest the low influence of fresh water on zooplankton population densities, even at the shallow stations where penetration of fresh water in the surface layers was notable.Po prvi put su prikazani sastav, abundancija i vertikalna struktura mikro- i mezozooplanktona u albanskim obalnim i otvorenim vodama. Istraživanje je obavljeno na šest postaja duž 75 km dugom transektu od šelfa do kontinentskog slaza. Najbrojniji predstavnici mikrozooplanktona su bili kopepodni naupliji (maksimum: 39 ind. L-1), iza kojih su slijedili kalanoidni i ciklopoidni kopepoditi. Od 14 zabilježenih vrsta tintinida, najbrojnija je bila vrsta Tintinnopsis radix, nađena od površine do 50 m dubine. Sastav zajednice mezozooplanktona obalnog i otvorenog mora u skladu je s prijašnjim istraživanjima južnog Jadrana. Kopepod Oithona similis bila je dominantna vrsta na svim istraživanim postajama. Na plićim postajama slijede je vrste Oithona plumifera, Acartia clausi, Paracalanus parvus, Oithona nana i cyclopoida-oncaeids, a u otvorenim vodama vrste Clausocalanus pergens, Oithona plumifera i Oithona nana. Bioraznolikost mezozooplanktona značajno raste od obale prema otvorenom moru. Nasuprot tome, najveća gustoća mezozooplanktona (2286 ind. m-3) zabilježena je na najplićoj postaji. Prisutnost karakterističnih vrsta tintinida i kopepoda otvorenog mora na obalnim postajama ukazuju na utjecaj struja otvorenog mora za vrijeme ovog istraživanja. Naši rezultati ukazuju da povećani upliv slatke vode nije znatno utjecao na gustoću zooplanktonskih populacija čak i na plitkim postajama gdje je prodor slatke vode u površinskim slojevima osobito izražen

Scyphomedusae and Ctenophora of the Eastern Adriatic: Historical Overview and New Data

One of the obstacles to detecting regional trends in jellyfish populations is the lack of a defined baseline. In the Adriatic Sea, the jellyfish fauna (Scyphozoa and Ctenophora) is poorly studied compared to other taxa. Therefore, our goal was to collect and systematize all available data and provide a baseline for future studies. Here we present phenological data and relative abundances of jellyfish based on 2010–2019 scientific surveys and a “citizen science” sighting program along the eastern Adriatic. Inter-annual variability, seasonality and spatial distribution patterns of Scyphomedusae and Ctenophore species were described and compared with existing historical literature. Mass occurrences with a clear seasonal pattern and related to the geographical location were observed for meroplanktonic Scyphomedusae Aurelia solida, Rhizostoma pulmo, and to a lesser extent Chrysaora hysoscella, Cotylorhiza tuberculata and Discomedusa lobata. Holoplanktonic Pelagia noctiluca also formed large aggregations, which were seasonally less predictable and restricted to the central and southern Adriatic. Four species of Ctenophora produced blooms limited to a few areas: Bolinopsis vitrea, Leucothea multicornis, Cestum veneris and the non-native Mnemiopsis leidyi. However, differences between Adriatic subregions have become less pronounced since 2014. Our results suggest that gelatinous organisms are assuming an increasingly important role in the Adriatic ecosystem, which may alter the balance of the food web and lead to harmful and undesirable effects

La poco nota medusa Drymonema dalmatinum Haeckel 1880 (Scyphozoa, Discomedusae) nel Mare Adriatico

Authors report historical and recent records of the little-known medusa Drymonema dalmatinum in the Adriatic Sea. This large scyphomedusa, which may develop a bell diameter of more than 1 m, was fi rst described in 1880 by Haeckel based on four specimens collected near the Dalmatian island Hvar. The paucity of this species records since its description confi rms its rarity, however, in the last 15 years sightings of D. dalmatinum have been more frequent.Gli autori riportano segnalazioni storiche e recenti della poco conosciuta medusa Drymonema dalmatinum nel mare Adriatico. Questa grande scifomedusa, che può sviluppare un cappello di diametro di oltre 1 m, è stata descritta per la prima volta nel 1880 da Haeckel, in base a quattro esemplari catturati vicino all’isola di Lèsina (Hvar) in Dalmazia. La scarsità delle segnalazioni di questa specie dalla sua prima descrizione conferma la sua rarità. Tuttavia, negli ultimi 15 anni gli avvistamenti di D. dalmatinum sono stati più frequenti