Faculty of Health and Environmental Sciences (Te Ara Hauora A Pūtaiao)

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Faculty of Health and Environmental Sciences - Te Ara Hauora A Pūtaiao encompasses the
  • School of Clinical Sciences - Te Kura Mātai Haumanu
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    Browsing Faculty of Health and Environmental Sciences (Te Ara Hauora A Pūtaiao) by Subject "0405 Oceanography"

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      Bioluminescence in Cephalopods: Biodiversity, Biogeography and Research Trends
      (Frontiers Media SA, 2023-06-27) Otjacques, E; Pissarra, V; Bolstad, K; Xavier, JC; McFall-Ngai, M; Rosa, R
      Numerous terrestrial and marine organisms, including cephalopods, are capable of light emission. In addition to communication, bioluminescence is used for attraction and defense mechanisms. The present review aims to: (i) present updated information on the taxonomic diversity of luminous cephalopods and morphological features, (ii) describe large-scale biogeographic patterns, and (iii) show the research trends over the last 50 years on cephalopod bioluminescence. According to our database (834 species), 32% of all known cephalopod species can emit light, including oegopsid and myopsid squids, sepiolids, octopuses, and representatives of several other smaller orders (bathyteuthids, and the monotypic vampire “squid”, Vampyroteuthis infernalis and ram’s horn “squid”, Spirula spirula). Most species have a combination of photophores present in different locations, of which light organs on the head region are dominant, followed by photophores associated with the arms and tentacles and internal photophores. Regarding the biogeographic patterns of cephalopod species with light organs, the most diverse ocean is the Pacific Ocean, followed by the Atlantic and Indian Oceans. The least diverse are the Southern and the Arctic Oceans. Regarding publication trends, our systematic review revealed that, between 1971 and 2020, 277 peer-reviewed studies were published on bioluminescent cephalopods. Most research has been done on a single species, the Hawaiian bobtail squid Euprymna scolopes. The interest in this species is mostly due to its species-specific symbiotic relationship with the bacterium Vibrio fischeri, which is used as a model for the study of Eukaryote–Prokaryote symbiosis. Because there are many knowledge gaps about the biology and biogeography of light-producing cephalopods, new state-of-the-art techniques (e.g., eDNA for diversity research and monitoring) can help achieve a finer resolution on species’ distributions. Moreover, knowledge on the effects of climate change stressors on the bioluminescent processes is nonexistent. Future studies are needed to assess such impacts at different levels of biological organization, to describe the potential broad-scale biogeographic changes, and understand the implications for food web dynamics.
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      Combining Multiple Stable Isotope Methods Elucidates Diet, Trophic Position and Foraging Areas of Southern Ocean Humpback Whales Megaptera novaeangliae
      (Inter-Research Science Center, 2024) Bury, SJ; Peters, KJ; Sabadel, AJM; St. John Glew, K; Trueman, C; Wunder, MB; Cobain, MRD; Schmitt, N; Donnelly, D; Magozzi, S; Owen, K; Brown, JCS; Escobar-Flores, P; Constantine, R; O’Driscoll, RL; Double, M; Gales, N; Childerhouse, S; Pinkerton, MH
      Southern Ocean humpback whales Megaptera novaeangliae are capital breeders, breeding in the warm tropics/subtropics in the winter and migrating to nutrient-rich Antarctic feeding grounds in the summer. The classic feeding model is for the species to fast while migrating and breeding, surviving on blubber energy stores. Whilst northern hemisphere humpback whales are generalists, southern hemisphere counterparts are perceived as krill specialists, but for many populations, uncertainties remain regarding their diet and preferred feeding locations. This study used bulk and compound-specific stable isotope analyses and isoscape-based feeding location assignments to assess the diet, trophic ecology and likely feeding areas of humpback whales sampled in the Ross Sea region and around the Balleny Islands. Sampled whales had a mixed diet of plankton, krill and fish, similar to the diet of northern hemisphere humpback whales. Proportions of fish consumed varied but were often high (2-60%), thus challenging the widely held paradigm of Southern Ocean humpback whales being exclusive krill feeders. These whales had lower 15N values and trophic position estimates than their northern hemisphere counterparts, likely due to lower Southern Ocean baseline 15N surface water values and a lower percentage consumption of fish, respectively. Most whales fed in the Ross Sea shelf/slope and Balleny Islands high-productivity regions, but some isotopically distinct whales (mostly males) fed at higher trophic levels either around the Balleny Islands and frontal upwelling areas to the north, or en route to Antarctica in temperate waters off southern Australia and New Zealand. These results support other observations of humpback whales feeding during migration, highlighting the species’ dietary plasticity, which may increase their foraging and breeding success and provide them with greater resilience to anthropogenically mediated ecological change. This study highlights the importance of combining in situ field data with regional-scale isoscapes to reliably assess trophic structure and animal feeding locations, and to better inform ecosystem conservation and management of marine protected areas.
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      Mitigation of Vibrio-Induced Metabolic Perturbations in Argopecten purpuratus Scallop Larvae via Probiotic Pretreatment
      (MDPI AG, 2024-07-06) Muñoz-Cerro, K; Venter, L; Young, T; Alfaro, AC; Brokordt, K; Schmitt, P
      Background: The decrease in the production of Argopecten purpuratus scallops in Chile is linked to extensive larval deaths in hatcheries caused by bacterial pathogens, particularly Vibrio genus, threatening sustainability. Traditional antibiotic practices raise concerns, urging research on eco-friendly strategies like bacterial probiotics. This study explores the metabolic responses of scallop larvae to Vibrio bivalvicida and evaluates the impact of the Psychrobacter sp. R10_7 probiotic on larval metabolism pre- and post-infection. Materials and Methods: Analysis detected 183 metabolite features, revealing significant changes in larval metabolites during Vibrio infection. Larvae pretreated with probiotics showed a metabolic profile comparable to non-infected larvae, indicating low impact on larval metabolome, likely due to probiotics antagonistic effect on pathogens. Results: Arachidonic acid, eicosatrienoic acid, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and docosapentaenoic acid (DPA) were significantly higher in non-pretreated/infected larvae compared to both pretreated/infected and non-pretreated/non-infected larvae, potentially supporting the activation of immune response in non-pretreated larvae to Vibrio infection. Identification of 76 metabolites provided insights into scallop larvae metabolome, highlighting the enriched metabolic pathways associated with energy provision and immune response. Conclusions: Probiotic pretreatment may mitigate metabolic disruptions in scallop larvae caused by Vibrio infection, suggesting a promising strategy for sustainable scallop production.
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