In a time when we are deluged with “big data”, it is easy to forget that there are still plenty of species that we don’t know much about. A common conservation dilemma is how to monitor or protect species when information about population sizes, distribution, or habitat preferences is lacking.
Such is the “little data” plight of many noncommercial freshwater species like Olympic mudminnow (Novumbra hubbsi), a highly endemic species found only here in Washington State. Distributed primarily in a single river drainage (the Chehalis River Basin), Olympic mudminnow by far have the smallest range of any of the five species of mudminnow worldwide. Based on this small range and some evidence of population declines, the state listed Olympic mudminnow as ‘State Sensitive’ in 1999, a designation for species likely to decline in the future without some proactive management or removal of threats.
When I started working on a FEC lab project on aquatic weed management in the Chehalis River Basin, we chose Olympic mudminnow as a focal species partly to try and bolster information related to conservation status. We found that even basic information on life history, ecology, and habitat occupancy was often not available. How old did they get? No one knew. How many eggs did females produce? Undetermined. Why were they found in this wetland but not the similar one around the bend? Puzzling.
Turning to the research for the other four species of mudminnow for answers, we found the same story: articles were typically short and based on small studies conducted in local ponds and streams. But unless funding for large-scale mudminnow research was on the horizon, these research nuggets were the best information available. What’s more, they almost begged to be compiled and interpreted as a whole to help researchers working on individual mudminnow species. This is how the review article “Ecology and Conservation of Mudminnow Worldwide” was born.
Although the number of peer-reviewed articles for each of the five mudminnow species was limited (10-12 on average, many devoted to genetic relationships), as a body the literature was very illuminating. We learned that all five species are habitat specialists, thriving in shallow and densely vegetated swamps, ponds, and bogs. They have innovative adaptations to thrive in these often harsh and changeable environments, with unique tolerances to low pH (Eastern mudminnow), dissolved oxygen (all species), and cold (Alaskan blackfish and Olympic mudminnow). Central mudminnow have even been shown to “sip” air bubbles under water when oxygen is low. Across all species, mudminnow also have fairly complex courtship, mating, and nesting rituals.
The review process not only illuminated these kinds of biodiversity secrets, but we were also able to illustrate why two species (European mudminnow and Olympic mudminnow) warrant conservation concern and outline significant threats to populations. Because mudminnow are not very mobile, a primary threat is water regulation which reduces or alters mudminnow habitat, particularly during spawning season. Interactions with non-native species and pollution are also implicated, but this could bear more investigation. We were also able to identify knowledge gaps for individual species, and make focused recommendations for future research.
As I worked on this project, I came to appreciate not only the fascinating adaptations of mudminnow, but also the power of scientific review to battle the problem of “little data” in conservation. While not a true substitute for species-specific research, reviews can be a proactive step toward filling knowledge gaps, particularly when a need for conservation concern or management is suspected.