Search

Quantifying the ecological importance of individual habitats to highly mobile animals is challenging because patterns of habitat reliance for these taxa are complex and difficult to observe. We investigated the importance of lagoons to the manta ray, Manta alfredi, a wide-ranging and vulnerable species in a less-disturbed atoll ecosystem. Lagoons are highly sensitive to anthropogenic disturbance and are known to be ecologically important to a wide variety of mobile species. We used a novel combination of research tools to examine the reliance of M. alfredi on lagoon habitats. Stable isotope analysis was used to assay the recent energetic importance of lagoons to M. alfredi; high-resolution tracking data provided information about how M. alfredi utilised lagoonal habitats over long and short time periods; acoustic cameras logged patterns of animal entrances and departures from lagoons; and photo identification/laser photogrammetry provided some insight into why they may be using this habitat. M. alfredi showed strong evidence of energetic dependence on lagoon resources during the course of the study and spent long periods of residence within lagoons or frequently transited into them from elsewhere. While within lagoons, they demonstrated affinities for particular structural features within this habitat and showed evidence of temporal patterning in habitat utilization. This work sheds light on how and why M. alfredi uses lagoons and raises questions about how this use may be altered in disturbed settings. More generally, these observations contribute to our knowledge of how to assess the ecological importance of particular habitats situated within the broader home range of mobile consumers., Introduction Mobile animals have been heavily impacted by anthropogenic activity in both terrestrial (e.g., wolves, mountain lion, African wild dog) and marine settings (e.g., whales, sharks, tuna) (Noss et al. [...]

A pronounced north-south multitaxon genetic discontinuity occurs in central New Zealand (NZ). Polymorphic microsatellite markers have been used to test the location and structure of this discontinuity in the endemic greenshell mussel, Perna canaliculus. Nine neutral loci revealed limited evidence of genetic structure, but one outlier locus (Pcan1-27) which may be under selection provided evidence of the discontinuity in central NZ. Whilst the limited multilocus evidence of structure is assumed to result from high levels of gene flow among populations of this continuously distributed species, assignment tests indicated high to very high mean levels of self-recruitment within the 14 populations and the north and south regions. The nine neutral loci were unable to provide further clarification as to the geographic location of the discontinuity, whereas the Pcan1-27 locus was particularly informative. These results highlight a tension between limited evidence of genetic structure and presumptive high gene flow among populations versus high levels of self-recruitment and pronounced structure depending on microsatellite loci and analyses in question. Evidence from all 10 loci indicates that the genetic discontinuity is maintained by high levels of self-recruitment, and evidence from Pcan1 -27 suggests that selection may also be important in explaining the existence of the discontinuity., Introduction Recent research highlights the importance of a variety of phenomena such as upwelling, coastal currents and wind-driven circulation to explain variation in the dispersal and site-specific supply of the [...]

The importance of considering ecological connectivity in the design of marine protected areas (MPAs) and ecologically coherent networks of protected areas across coasts and oceans has risen in prominence with the 2022 Kunming-Montreal Global Biodiversity Framework. This short communication highlights key messages emerging from a specialist conference session on marine connectivity by members of the IUCN-WCPA Marine Connectivity Working Group at the Fifth International Marine Protected Areas Congress (IMPAC5) in Vancouver in 2023. We consider the importance of spatial and temporal scale, knowledge and data gaps and some of the technological and scientific advances that are generating insights into species movements that can inform the ecologically meaningful design of protected areas for effective conservation of ecosystem integrity, biodiversity and the flow of ecosystem services. [ABSTRACT FROM AUTHOR]

High levels of shared allozyme polymorphism have been found in three species of strongly differentiated congeneric clams of the Astarte genus. Biochemical genetic variation at 12 allozyme loci has been studied in the sympatrically occurring species from one location off the coast of Newfoundland, on the east coast of Canada. Time of speciation events seems consistent with the period proposed for rapid speciation in North Atlantic bivalves after major extinction event. Allozyme variation in the species was only related to allele frequency differences. No absolute, or fixed, differences were seen. Absence of diagnostic allelic differences is quite unusual.

Smooth-shelled blue mussels of the Mytilus edulis species complex are widely distributed bivalve molluscs whose introductions threaten native marine biodiversity (non-indigenous species - NIS). The aim of the present study was to identify the species and hybrids of Mytilus present in the Magellan Region (southern Chile). Results indicate that three mussel species of the Mytilus edulis complex are found in the region - M. edulis, M. chilensis (or the Southern Hemisphere lineage of Mytilus galloprovincialis), and M. galloprovincialis of Northern Hemisphere origin. For the first time, alleles of the introduced M. trossulus are reported from the Southern Hemisphere. In the Strait of Magellan the native Pacific blue mussel, Mytilus chilensis and the native Atlantic blue mussel, Mytilus edulis, meet and mix at a natural hybrid zone (about 125 km in length). This is the first record of a natural Mytilus hybrid zone in the Southern Hemisphere and is also the first record of the co-occurrence of genes from all four Mytilus species in any one region. These results contribute to the knowledge of the biodiversity and delimitation of mussel species in southern South America, and highlight how introduced species may threaten the genetic integrity of native species through hybridization and introgression. [ABSTRACT FROM AUTHOR]

The taxonomic status of smooth shelled blue mussels of the genus Mytilus has received considerable attention in the last 25 years. Despite this, the situation in the southern hemisphere remains uncertain and is in need of clarification. Recent work suggests that contemporary New Zealand mussels from two cool/cold temperate locations are M. galloprovincialis. However, the distribution of Mytilus in New Zealand ranges from 35 ° to 52 ° south (∼ 1800 km), meaning that large areas of the subtropical/warm temperate north and the subantarctic south remain unsampled, an important consideration when species of this genus exhibit pronounced macrogeographical differences in their distributions which are associated with environmental variables such as water temperature, salinity, wave action and ice cover. This study employed multivariate morphometric analyses of one fossil, 83 valves from middens, and 92 contemporary valves from sites spanning the distributional range of blue mussels to determine a historical and contemporary perspective of the taxonomic status of Mytilus in New Zealand. The findings indicated that all fossil and midden mussels are best regarded as M. galloprovincialis and confirmed that contemporary mussels, with one possible regional exception, are also best regarded as M. galloprovincialis. Contemporary mussels from the Bay of Islands (warm temperate/subtropical) exhibited much greater affinity to M. edulis than they did to M. galloprovincialis, indicating that mussels from this area require detailed genetic examination to determine their taxonomic status. The analyses revealed a significant difference between the fossil/midden mussels and the contemporary mussels, consistent with levels of present day differentiation among intraspecific populations and not thought to reflect any substantive temporal change between mussels of the two groups. The continuous distribution of M. galloprovincialis in New Zealand from the warm north to the subantarctic south indicates that the physiology of this species is adapted to a wide range of water temperature conditions. Therefore, the distribution of this species on a worldwide scale is unlikely to be restricted by its adaptation to warm water alone, as has previously been widely assumed. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 82, 329–344. [ABSTRACT FROM AUTHOR]