The global mio-pliocene climatic equability and coastal ostracod faunas of southeast Australia

This study on the Mio–Pliocene ostracod successions of southeast Australia outlines several faunal events indicative of climate warming and/or increased rainfall events. Ostracod faunas associated with a late Late Miocene sea level rise event suggest that the climate of this time in southeast Australia was similar to, or slightly warmer than that of present day southeast Australia. However, it was probably wetter and significantly warmer than immediately preceding (mid Late Miocene) palaeoclimatic conditions within the region. Evidence for a change to wetter and warmer conditions during the late Late Miocene is seen in the appearance of various extant euryhaline and semi-thermophilic ostracod species in coastal ostracod faunas. The appearance of euryhaline species, which are mostly absent from older shallow marine Cenozoic strata of the Bass Strait hinterland, suggests a major influx of fresh water into coastal marine settings, which contributed to the initial phase of development of the southeast Australian late Neogene barrier coastline and associated marginal marine palaeoenvironments.

During the time interval latest Miocene to earliest Pliocene, and during the early Late Pliocene, two subsequent global sea level rise events are also preserved in the southeast Australian coastal plain. Many of the species present in ostracod faunas associated with these two events are the same as in older local late Late Miocene faunas. In earliest (?) Pliocene faunas, there is minor evidence for the reappearance of semi-thermophilic ostracods. Faunas of early Late Pliocene age often exhibit a conspicuous faunal dominance by, or large abundance of euryhaline species, indicating the particularly strong influence of fresh water influxes into coastal marine palaeoenvironments. This may reflect the presence of especially wet local temperate palaeoclimatic conditions during a time of equable global climates.

Succeeding estuarine, lagoonal and coastal embayment ostracod faunas of late Late Pliocene age are associated with marginal marine sediments that are interbedded with coastal dune aeolianites. This suggests an overall seaward retreat of marginal marine environments that was initiated by a major global sea level fall linked to the onset of cooler Late Pliocene and Quaternary global climates.

The broad-scale distribution of five jellyfish species across a temperate coastal environment

Jellyfish (medusae) are sometimes the most noticeable and abundant members of coastal planktonic communities, yet ironically, this high conspicuousness is not reflected in our overall understanding of their spatial distributions across large expanses of water. Here, we set out to elucidate the spatial (and temporal) patterns for five jellyfish species (Phylum Cnidaria, Orders Rhizostomeae and Semaeostomeae) across the Irish & Celtic Seas, an extensive shelf-sea area at Europe’s northwesterly margin encompassing several thousand square kilometers. Data were gathered using two independent methods: (1) surface-counts of jellyfish from ships of opportunity, and (2) regular shoreline surveys for stranding events over three consecutive years. Jellyfish species displayed distinct species-specific distributions, with an apparent segregation of some species. Furthermore, a different species composition was noticeable between the northern and southern parts of the study area. Most importantly, our data suggests that jellyfish distributions broadly reflect the major hydrographic regimes (and associated physical discontinuities) of the study area, with mixed water masses possibly acting as a trophic barrier or non-favourable environment for the successful growth and reproduction of jellyfish species.