Biology subjects

Guy-Haim, T.

Publications and source records attributed to Guy-Haim, T..

4 recordsLinked to original sources

bioRxiv2026

Global patterns of helminths associated with gelatinous zooplankton: a missing link in marine parasite transmission

Gelatinous zooplankton are abundant predators and prey in marine food webs, yet their role in helminth (parasitic worms) transmission remains poorly resolved. Here we combine a global synthesis of published records with new morphological and molecular observations from the Mediterranean, Red, Celtic, Baltic and North Seas to assess the ecological role of helminths associated with gelatinous zooplankton. We compiled 431 host-parasite association records from 89 sources, including 23 new records, and show that helminth occurrence and richness in gelatinous hosts are concentrated at temperate latitudes, contrasting with the classical latitudinal diversity gradient. Our sampling revealed markedly higher parasite prevalence, abundance and diversity in the Red Sea than in the Mediterranean, while no helminths were detected in gelatinous zooplankton sampled from the Baltic and North Seas. All helminths recorded were larval stages, indicating that gelatinous zooplankton function as key intermediate hosts in marine helminth life cycles. Molecular analyses identified cestodes, nematodes and digenean trematodes associated with cnidarians, ctenophores, and chaetognaths, including the first record of trematode larvae in a pelagic tunicate. Our findings challenge the view of gelatinous zooplankton as dead-end hosts and identify them as overlooked vectors that may shape marine parasite biogeography, food web connectivity and invasion dynamics.

ecology↗

bioRxiv2023

Shedding light on the Ophel biome: The Trans-Tethyan phylogeography of the sulfide shrimp Tethysbaena (Peracarida: Thermosbaenacea) in the Levant

Tethysbaena are small peracarid crustaceans found in extreme environments such as subterranean lakes and thermal springs, represented by endemic species found around the ancient Tethys, including the Mediterranean, Arabian Sea, Mid-East Atlantic, and the Caribbean Sea. Two Tethysbaena species are known from the Levant: T. relicta, inhabiting the Dead Sea-Jordan Rift Valley, and T. ophelicola, found in the Ayyalon cave complex in the Israeli coastal plain, both belonging to the same species-group based on morphological cladistics. Along the biospeleological research of the Levantine subterranean fauna, three biogeographic hypotheses determining their origins were proposed: (1) Pliocenic transgression, (2) Mid-late Miocenic transgression, and (3) The Ophel Paradigm, according to which these are inhabitants of a chemosynthetic biome as old as the Cambrian. We have used mtDNA COI gene and a molecular clock approach to establish the phylogeny and assess the divergence times of the Levantine Tethysbaena. Contrary to prior hypotheses, our results indicate a two-stage colonization pattern: a late Oligocene transgression, through a marine gulf extending from the Arabian Sea, leading to the colonization of T. relicta in the Dead Sea-Jordan Rift Valley, and a Miocene transgression in the emerging Mediterranean region, carrying T. ophelicola to the coastal plain of Israel.

zoology↗

bioRxiv2023

Tar patties are hotspots of hydrocarbon turnover and nitrogen fixation during a nearshore pollution event in the oligotrophic southeastern Mediterranean Sea

Weathered oil, that is, tar, forms hotspots of hydrocarbon degradation by complex biota in marine environment. Here, we used marker gene sequencing and metagenomics to characterize the communities of bacteria, archaea and eukaryotes that colonized tar patties and control samples (wood, plastic), collected in the littoral following an offshore spill in the warm, oligotrophic southeastern Mediterranean Sea (SEMS). We show aerobic and anaerobic hydrocarbon catabolism niches on tar interior and exterior, linking carbon, sulfur and nitrogen cycles. Alongside aromatics and larger alkanes, short-chain alkanes appear to fuel dominant populations, both the aerobic clade UBA5335 (Macondimonas), anaerobic Syntropharchaeales, and facultative Mycobacteriales. Most key organisms, including the hydrocarbon degraders and cyanobacteria, have the potential to fix dinitrogen, potentially alleviating the nitrogen limitation of hydrocarbon degradation in the SEMS. We highlight the complexity of these tar-associated communities, where bacteria, archaea and eukaryotes co-exist, exchanging metabolites and competing for resources and space. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=68 SRC="FIGDIR/small/546273v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@7ff1eborg.highwire.dtl.DTLVardef@1e39012org.highwire.dtl.DTLVardef@107c307org.highwire.dtl.DTLVardef@95073f_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

bioRxiv2022

Trophic ecology of deep-sea megafauna in the ultra-oligotrophic Southeastern Mediterranean Sea

The trophic ecology of fourteen species of bathybenthic and bathypelagic fishes and six species of bathybenthic decapod crustaceans from the continental slope and rise of the Southeastern Mediterranean Sea (SEMS) was examined using stable isotope analysis. Mean {delta}13C values among fish species varied by more than 4.0{per thousand}, from -20.85{per thousand} (Macroramphosus scolopax) to -16.57{per thousand} (Conger conger and Centrophorus granulosus), and increased as a function of depth (200 - 1400 m). Mean {delta}13C values of the crustaceans showed smaller variation, between -16.38{per thousand} (Polycheles typhlops) and -18.50{per thousand} (Aristeus antennatus). This suggests a shift from pelagic to regenerated benthic carbon sources with depth. Benthic carbon regeneration is further supported by the low benthic-pelagic POM-{delta}13C values, averaging -24.7 {+/-} 1.2{per thousand}, and the mixing model results, presenting very low contribution of epipelagic POM to the bathyal fauna. Mean {delta}15N values of fish and crustacean species ranged 7.91 {+/-} 0.36{per thousand} to 11.36 {+/-} 0.39{per thousand} and 6.15 {+/-} 0.31{per thousand} to 7.69 {+/-} 0.37{per thousand}, respectively, resulting in trophic position estimates, occupying the third and the fourth trophic levels. Thus, despite the proximity to the more productive areas of the shallow shelf, low number of trophic levels (TL~1.0) and narrow isotopic niche breadths (SEAc <1) were observed for bathybenthic crustaceans (TL = 3.62 {+/-} 0.22) and bathypelagic fishes (TL = 4.33 {+/-} 0.34) in the study area - probably due to the ultra-oligotrophic state of the SEMS resulting in limited carbon sources. Our results, which provide the first trophic description of deep-sea megafauna in the SEMS, offer insight into the carbon sources and food web structure of deep-sea ecosystems in oligotrophic marginal seas, and can be further used in ecological modeling and support the sustainable management of marine resources in the deep Levantine Sea.

ecology↗