Effects of environmental variables on the distribution of juvenile cubomedusae Carybdea marsupialis in the coastal Western Mediterranean

Abstract

Relationships between environmental factors and oscillations in jellyfish abundance, especially in the early life stages, could help to interpret past increases and also predict scenarios in a changing future. For the first time, we present cubozoan spatial and temporal distributions in the earliest stages and their relationships with different factors. Abundances of Carybdea marsupialis medusae showed high interannual variability from 2008 to 2014 along the Dé nia coast (SE Spain, W Mediterranean). During 2015, samples were collected from 11 beaches along 17 km of coastline, 8 times from January to November in order to determine the effects of environmental factors on the distribution of juvenile C. marsupialis. Juveniles (� 15 mm diagonal bell width) were present from May to July, with more sampled near shore (0-15 m). Most of them occurred in June when their numbers were unequal among beaches (average 0.05 ind m-3 , maximum 6.71 ind m-3). We tested distributions of juveniles over time and space versus temperature, salinity, nutrients (N, P and Si), chlorophyll-a (Chla), and zooplankton abundance. Temperature and cladocerans (zooplankton group) were significantly positively correlated with juvenile distribution, whereas Chl-a concentration was weakly negative. By contrast, in 2014, high productivity areas (Chl-a and zooplankton) overlapped the maximum adult abundance (5.2 ind m-3). The distribution of juveniles during 2015 did not spatially coincide with the areas where ripe adults were located the previous year, suggesting that juveniles drift with the currents upon release from the cubopolyps. Our results yield important insights into the complexity of cubozoan distributions.

Environmental drivers of the occurrence and abundance of the Irukandji jellyfish (Carukia barnesi)

“…Jellyfish, more commonly scyphozoan species, are well known for their capacity to occur in large numbers and singular ‘bloom’ events, tallying thousands of individuals, have been reported worldwide [ 16 ]. However, current literature supporting cubozoan abundance of this magnitude is sparse with only a small number of studies, reporting the occurrence of cubo-medusa in comparative numbers [ 14 , 28 , 37 , 38 ]. While the presence of larger catch days in our study, where C .…”

“…Environmental predictors were collated from several sources and selected based on historical data availability and significance in previous studies [ 13 – 15 , 22 , 28 ]. Moon visibility, analyzed as the percent of moon disk illuminated, was matched to historical dates using the lunar illuminate function from the R ‘Lunar’ package [ 29 ].…”

“…Data were then analyzed via a logistic regression model. Logistic regression is well-suited for the binary (presence/absence) nature of these data and has been used previously to associate patterns of jellyfish presence with environmental variables [15,28,32]. The second part of the hurdle model, the count data model, was aimed at investigating drivers of C. barnesi abundance patterns when counts were greater than zero.…”

“…species, are well known for their capacity to occur in large numbers and singular 'bloom' events, tallying thousands of individuals, have been reported worldwide [16]. However, current literature supporting cubozoan abundance of this magnitude is sparse with only a small number of studies, reporting the occurrence of cubo-medusa in comparative numbers [14,28,37,38]. While the presence of larger catch days in our study, where C. barnesi catch tallies were greater than 100 individuals, do demonstrate that large aggregations of C. barnesi are certainly possible the small frequency of these catch tallies over the experimental period, and consequently the consistency of 'low catch tallies', suggest these are uncommon.…”

Integrating complexity in population modelling: from matrix to dynamic models using the jellyfishCarybdea marsupialis

“…While the abundance of cubozoans in coastal waters is generally low and uneven (Kingsford & Mooney, 2014), there are certain locations where their density can reach high numbers. Examples include Alatina moseri in Hawaii, Alatina alata in the Caribbean Netherlands and Alatina mordens in Australia (Lawley et al, 2016), as well as C. marsupialis on the south-western Spanish coast, northeast Atlantic (Rodríguez-García et al, 2021) and the Western Mediterranean, where they can be responsible for most of the stings that occur on some beaches where this species is present as a resident species since it is not advected by currents in its adult stage (Bordehore et al, 2011; Bordehore et al, 2020).…”