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Marine Biogeography (marine + biogeography)
Selected AbstractsMarine biogeography and ecology: invasions and introductionsJOURNAL OF BIOGEOGRAPHY, Issue 2 2007John C. Briggs Abstract Although biogeography and ecology had previously been considered distinct disciplines, this outlook began to change in the early 1990s. Several people expressed interest in creating a link that would help ecologists become more aware of external influences on communities and help biogeographers realize that distribution patterns had their genesis at the community level. They proposed an interdisciplinary approach called macroecology. This concept has been aided by the advent of phylogeography, for a better knowledge of genetic relationships has had great interdisciplinary value. Two areas of research that should obviously benefit from a macroecological approach are: (1) the question of local vs. regional diversity and (2) the question of whether invader species pose a threat to biodiversity. The two questions are related, because both deal with the vulnerability of ecosystems to penetration by invading species. Biogeographers, who have studied the broad oceanic patterns of dispersal and colonization, tend to regard isolated communities as being open to invasion from areas with greater biodiversity. It became evident that many wide-ranging species were produced in centres of origin, and that the location of communities with respect to such centres had a direct effect on the level of species diversity. Ecologists, in earlier years, thought that a community could become saturated with species and would thereafter be self-sustaining. But recent research has shown that saturation is probably never achieved and that the assembly of communities and their maintenance is more or less dependent on the invasion of species from elsewhere. The study of invasions that take place in coastal areas, usually the result of ship traffic and/or aquaculture imports, has special importance due to numerous opinions expressed by scientists and policy-makers that such invasions are a major threat to biodiversity. However, none of the studies so far conducted has identified the extinction of a single, native marine species due to the influence of an exotic invader. Furthermore, fossil evidence of historical invasions does not indicate that invasive species have caused native extinctions or reductions in biodiversity. [source] Marine biogeography of southern Australia: phylogeographical structure in a temperate sea-starJOURNAL OF BIOGEOGRAPHY, Issue 12 2003Jonathan M. Waters Abstract Aim, To test whether marine biogeographical patterns observed at the community level are also important within species. It is postulated that historical hydrogeographic barriers have driven in situ diversification. Location, The intertidal and shallow subtidal zones of southern Australia, New Zealand and nearby islands. Australia's temperate marine communities are characterized by a high degree of endemism and show strong biogeographical structure along an east,west axis. Methods, Phylogeographical analysis of the widespread asteriid sea-star Coscinasterias muricata Verrill across southern Australia and New Zealand. Forty-two samples from 27 locations were included in phylogenetic analyses of mitochondrial (CO1; control region) and nuclear (ITS2) DNA sequences. Results, Analysis of mtDNA revealed a deep phylogenetic split within Australian C. muricata, strongly correlated with latitude. ,Northern' haplotypes (latitude , 37.6° S, nine sites, 15 samples) were 7.3,9.4% divergent from ,southern' haplotypes (latitude , 37.6° S, 19 sites, 27 samples), consistent with late Pliocene separation. Eastern and western representatives of the ,northern' clade were 0.5,1.0% divergent, probably reflecting Pleistocene isolation. The ,southern' clade of Australia is also represented in New Zealand, indicating Pleistocene oceanic dispersal. Nuclear DNA (ITS2) sequences yielded relatively little phylogenetic resolution, but were generally congruent with mtDNA-based groupings. Main conclusions, The phylogeographical pattern detected within Australian C. muricata closely resembles marine biogeographical groupings proposed on the basis of community and species distributions. Recurring evolutionary patterns may have been driven by the hydrographic history of southern Australia. Specifically, we suggest that Plio-Pleistocene temperature change and the repeated opening and closure of Bass Strait promoted allopatric divergence and perhaps cryptic speciation in C. muricata. [source] TEMPERATURE THRESHOLD AS A BIOGEOGRAPHIC BARRIER IN NORTHERN INDIAN OCEAN MACROALGAE,JOURNAL OF PHYCOLOGY, Issue 4 2006Tom Schils The most eastern point of the Arabian Peninsula, Ras Al Hadd, marks the boundary between the Arabian Sea and the Gulf of Oman. This geographic landmark coincides with an abrupt floristic turnover, probably one of the sharpest biotic transitions known in marine biogeography. The floras of different Arabian localities across this floristic break were compared using macrophyte distribution data throughout the Indian Ocean and seasonal sea-surface temperature (SST) data. The localities from the Arabian Gulf and Gulf of Oman differ significantly from those of the Arabian Sea based on their species richness, species composition, average distribution range per species, general temperature affinity of the composing species, and seasonal temperature data of the coastal waters. Pooling the temperature data into two groups (SST3avg, average SST of the three warmest seasons; SSTmin, minimum of the seasonal SSTs) revealed a temperature limit at 28°C using both the temperature affinity data of the floras and the seasonal temperatures recorded for the specific Arabian localities, which significantly separates the Arabian Sea from localities of both Gulfs. Finally, SST data of the Indian Ocean were analyzed using this upper temperature threshold of macrophytes at 28°C and the lower temperature limit of corals at 25°C, revealing general macrophyte diversity patterns. [source] Seamount science scales undersea mountains: new research and outlookMARINE ECOLOGY, Issue 2010Thomas A. Schlacher Abstract Conventional wisdom suggests that seamounts harbour high levels of biodiversity and endemism, play important roles in marine biogeography, are hotspots of biological carbon processing, and support substantial fisheries. However, since fewer than 300 seamounts have been thoroughly sampled, these generalizations remain largely untested. This has provided the motivation for a number of seamount-focused research projects in recent years, including CenSeam, a field project within the Census of Marine Life. This issue presents some of the research output facilitated by CenSeam. Here we summarize the main findings and provide a précis of future research directions highlighted by contributors to the issue. Recent studies show that seamounts can have comparable levels of benthic diversity and endemism to continental margins, but their communities also include a distinct composition of species that can attain higher biomass. Reported geographic differentiation among seamount communities suggests limited larval dispersal, local speciation, geographic isolation, or a combination of these processes. Genetic studies contained in the issue address these themes explicitly, documenting complex patterns of connectivity that depend on spatial scale and life history characteristics. Globally, seamount ecosystems are also under pressure from bottom-contact fishing and ocean acidification. Contributions detailing the footprint of trawling and a risk assessment confirm what has long been suspected: seamount ecosystems are highly vulnerable to disturbance by bottom trawling and recovery from fishing impacts is a lengthy process, likely requiring decades at a minimum. A predicted shallowing of the aragonite saturation horizon caused by ocean acidification is predicted to place deep-water corals at risk, but seamounts may yet provide a spatial/chemical refuge from these impacts. The issue concludes with a ,myth-buster' synthesis that updates the status of the various seamount ecological paradigms. [source] | ||||||||||