We don’t mention it often, but Craig and I publish regularly outside Deep Sea News, in the public arena of peer-reviewed scientific literature. Craig authors ~3 scientific journal articles per year since 2004. I author ~2/yr. The last two years were above average for both of us. This is amazing to me, because we spend so much time writing for DSN. Either our cups runneth over, or the glacial pace of scientific publishing obscures the impact of our extra-curricular reporting activities here at DSN. I tell you this so you know we are contributors to the field, not only journalists. We make the news and break the news.
The thing I like most about Craig’s work is that he’s a “big picture” guy. He likes to tackle sweeping ecological theories like the Island Effect, where big animals evolve smaller body sizes (think dwarf elephant) and small animals evolve bigger body sizes (think giant isopod). He likes to wrestle with broad hypotheses about seamount biogeography, wherein pundits conjecture about whether seamounts are more like isolated “islands” or interconnected “stepping stones”. Craig’s most recent “big-picture” paper was a guest editorial in the Journal of Biogeography entitled “Seamounts: identity crisis or split personality?” The paper is important because it helps to frame the debate about seamount biogeography. A brief review is given below.
A seamount is a large isolated submarine feature with relatively steep slopes compared to the surrounding seafloor. By the earliest definition, seamounts have more than 1000m vertical relief, so anything smaller would be considered a “mound”, a “rise”, or a “bank”. However, many biologists would tell you the 1000m relief definition is overly strict, because the benthic assemblages on these features can be similar. Nearly 14,000 seamounts have been identified using satellite altimetry and gravity data. Commercial and recreational fisheries target these features because of high productivity, and conservation groups have rallied around them because of localized depletions of long-lived fish species and high levels of non-target by-catch in bottom trawls and longlines.
One important question is whether these seamounts represent “islands” of isolated populations, whether they act as “island chains” of interconnected metapopulations, or whether they function more like “oases” for broadly dispersed and highly migratory species. In the last scenario, high productivity yields high biomass, which supports high species richness.
Of course, part of the answer depends upon which taxon you’re talking about. Craig cites different results depending on whether you are looking at bivalves, crabs, or corals. He notes that claims of seamount endemism are not well supported because the deep-sea often yields new species. Therefore, unless we have a good understanding of endemism in the surrounding abyssal plains and continental shelves, we have little to compare.
Consider collecting a single sea anemone that turns out to be a new species. How do you know it’s endemic? If you collected and preserved the only specimen known to science, for all we know, the species could now be extinct. Seamount endemism must be considered within the context of an overall deep-sea endemism. For instance, endemism at hydrothermal vents in nearly 75%. How do seamounts compare? Read the article to find out.
Ultimately, Craig provides 10 recommendations for further research, including a need for better biomass estimates, more molecular studies, more comparative studies of seamounts and non-seamount habitats, and an appropriate sampling design to test hypotheses of seamount endemism. This list will prove useful in coming years, because new research vessels will be coming online, and new shared enterprises will be forming using state-of-the-art technology. Census of Marine Life on Seamounts (CenSeam) is just one of the groups we need working on these problems.
There’s a lot of seamounts out there, folks. You can’t stop wondering… are they more like islands, or more like oases, or are they something else entirely?