Why Studying Marine Larvae is so Important
by Tom Lang
In their paper, Coastal pollution limits pelagic larval dispersal, published in Nature Communications on March 8, 2011, co-authors Jon Puritz and Breeder’s Registry co-founder Rob Toonen, Ph.D. of University of Hawaii’s Hawaii Institute of Marine Biology document linkages between human pollution and the lack of genetic diversity of the Bat Star (Patiria miniata) along California’s southern coast. The paper shows how human-caused runoff and effluent are acting as barriers to larval dispersal and that inland actions are indeed impacting a species that is normally free of direct human contact.
The fisheries of our planet, including the fisheries that provide us with the coral reef fishes and corals we all rely on for our marine aquariums, rely on new recruits from the plankton to replenish the individuals removed for our aquariums and other human uses. It is simple to say that a fishery is sustainable when new fishes and corals reappear year after year, but what happens when this process is interrupted by human-caused factors such as coastal pollution? This is where the study of larval forms of the creatures that populate the oceans suddenly becomes extremely important.
Breeding fishes and corals in aquariums represents an extraordinary opportunity to discover what is necessary to ensure survival of our ocean’s animals. When aquarists record high larval mortalities in water containing high levels of measured ammonium, we can extrapolate that untreated or under-treated effuent containing high ammonium discharged into the ocean and into rivers that flow to the ocean can likewise impact larval development in the wild.
Waste water treatment technologies collectively known as tertiary treatment exist today that can effectively remove the nitrogenous compounds that are injurious to larval organisms and plankton on coral reef and other coastal ecosystems. But even in the U.S. and other developed countries, it is astounding that not all waste water treatment facilties utilize this technology. The cost of the equipment is part of the problem, but in our more “ecologically enlightened” time it should not be controversial that such treatment would go a long way in making our coastal aquatic environments much more larvae friendly.
Another important facet of marine larvae study, and one that The Breeder’s Registry articles and Spawning Reports have been at the forefront since 1993, is the discovery of tiny food sources that are vital to larval survival. Again, ex situ observations in aquaria have led to a much better understanding of the very specific larval food requirements of dozens of marine species. What works for one species simply does not always work for another.