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16 result(s) for "MacIntosh, Hugh"
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Multiple observations of Bigfin Squid (Magnapinna sp.) in the Great Australian Bight reveal distribution patterns, morphological characteristics, and rarely seen behaviour
One of the most remarkable groups of deep-sea squids is the Magnapinnidae, known for their large fins and strikingly long arm and tentacle filaments. Little is known of their biology and ecology as most specimens are damaged and juvenile, and in-situ sightings are sparse, numbering around a dozen globally. As part of a recent large-scale research programme in the Great Australian Bight, Remotely Operated Vehicles and a towed camera system were deployed in depths of 946–3258 m resulting in five Magnapinna sp. sightings. These represent the first records of Bigfin Squid in Australian waters, and more than double the known records from the southern hemisphere, bolstering a hypothesis of cosmopolitan distribution. As most previous observations have been of single Magnapinna squid these multiple sightings have been quite revealing, being found in close spatial and temporal proximity of each other. Morphological differences indicate each sighting is of an individual rather than multiple sightings of the same squid. In terms of morphology, previous in-situ measurements have been roughly based on nearby objects of known size, but this study used paired lasers visible on the body of a Magnapinna squid, providing a more accurate scaling of size. Squid of a juvenile size were also recorded and are confirmed to possess the long distal filaments which have thus far been mostly missing from specimens due to damage. We have described fine-scale habitat, in-situ colouration, and behavioural components including a horizontal example of the ‘elbow’ pose, and coiling of distal filaments: a behaviour not previously seen in squid. These sightings add to our knowledge of this elusive and intriguing genus, and reinforce the value of imagery as a tool in deep-sea squid research.
Multiple observations of Bigfin Squid
One of the most remarkable groups of deep-sea squids is the Magnapinnidae, known for their large fins and strikingly long arm and tentacle filaments. Little is known of their biology and ecology as most specimens are damaged and juvenile, and in-situ sightings are sparse, numbering around a dozen globally. As part of a recent large-scale research programme in the Great Australian Bight, Remotely Operated Vehicles and a towed camera system were deployed in depths of 946-3258 m resulting in five Magnapinna sp. sightings. These represent the first records of Bigfin Squid in Australian waters, and more than double the known records from the southern hemisphere, bolstering a hypothesis of cosmopolitan distribution. As most previous observations have been of single Magnapinna squid these multiple sightings have been quite revealing, being found in close spatial and temporal proximity of each other. Morphological differences indicate each sighting is of an individual rather than multiple sightings of the same squid. In terms of morphology, previous in-situ measurements have been roughly based on nearby objects of known size, but this study used paired lasers visible on the body of a Magnapinna squid, providing a more accurate scaling of size. Squid of a juvenile size were also recorded and are confirmed to possess the long distal filaments which have thus far been mostly missing from specimens due to damage. We have described fine-scale habitat, in-situ colouration, and behavioural components including a horizontal example of the 'elbow' pose, and coiling of distal filaments: a behaviour not previously seen in squid. These sightings add to our knowledge of this elusive and intriguing genus, and reinforce the value of imagery as a tool in deep-sea squid research.
Shipworms as a model for competition and coexistence in specialized habitats
Shipworms, a group of marine wood borers (Mollusca: Teredinidae), are a model group with which to examine metacommunities inhabiting patchy, ephemeral habitats. Multiple species and genera typically share and compete for the same discrete substrata, allowing for direct comparisons to be made between competitive strategies, without confounding by extraneous biological differences. Timber recruitment panels were used to quantify 2, 4, 6 and 12 mo abundances of tropical Australian shipworm species, recording 62 075 individuals from 6 genera and 19 species. Species exhibit differing peak recruitment seasons and reproductive modes, with free-spawning, short-term brooding and long-term brooding occurring. However, despite a higher diversity of spawning species (58%) overall, abundance was strongly driven by the lower diversity of short-term brooding species (37%), comprising 95.7% of recruitment. Competition for habitat was high, with up to 1200 individuals per panel (~3 ind. cm–3), and widespread (40 to 90%) mortality in panels over 4 mo old. Results show that reproductive mode is a key contributor to recruitment success, with the constraints of a patchy, ephemeral habitat favoring a ‘middle of the road’ strategy of short duration larval brooding, most effectively balancing fecundity, larval retention, and dispersive ability.
Some new Haliclona species (Demospongiae, Haplosclerida) from British Columbia Shallow Waters and a Re-Description of Haliclona mollis (Lambe, 1893)
A numer of Haliclona species (Demospongiae, Haplosclerida) in the Austin and McDaniel collections at the Royal British Columbia Museum (RBCM) are identified only to genus or genus and species. The collections are representative of over 40 years of sampling principally by the late Dr. William C. Austin and one of us (Neil McDaniel) through SCUBA diving on the west coast of British Columbia and specimens provided by others to Dr. Austin. We have selected representative Haliclona species in the collections for detailed examination and placement in subgenera and species (where species were not identified). Haliclona is recognized to have several subgenera, thus identification of specimens to genus and species is incomplete. Our study updates this status for the species examined. Methods of collection included intertidal scrapings or removal of non-encrusting specimens usually accompanied by in-situ photos, similar methods at SCUBA diving depths (subtidal to 35 m) and from other dredging, trawling and biological sampling activities. We describe eleven new Haliclona (Demospongeae Haplosclerida Chalinadae) species and a range extension for Haliclona (Flagellia) edaphus de Laubenfels, 1930 for shallow waters of Southwestern British Columbia, Canada. New species include Haliclona (Gellius) hartmani n. sp., Haliclona (Gellius) shishalhensis n. sp., Haliclona (Reniera) gesteta n. sp., Haliclona (Rhizoniera) aborescens n. sp., Haliclona (Rhizoniera) blanca n. sp., Haliclona (Rhizoniera) boothensis n. sp., Haliclona (Rhizoniera) filix n. sp., Haliclona (Rhizoniera) kunechina n.sp., Haliclona (Rhizoniera) meandrina n. sp., Haliclona (Rhizoniera) penelakuta n. sp., and Haliclona (Rhizoniera) vulcana n. sp. We also redescribe Haliclona mollis (Lambe, 1893 [1894]) and propose placing it in the subgenus Haliclona. Except for Lambe’s syntype slides of Haliclona mollis which are deposited at the Canadian Museum of Nature, Ottawa, Canada, all holotypes and voucher specimens of species described are deposited at RBCM.