March 15 (UPI) — Kelp forests are vital to a diversity of marine species, new research shows, just as Charles Darwin predicted during his initial visit to the Galapagos Islands.
During Darwin’s 1835 research expedition, the famed naturalist surmised that the kelp forests ringing the islands were just as ecologically valuable as forests on land, if not more so.
In a new study, researchers at the University of California, Santa Barbara measured the benefits offered by kelp forests. Their findings, published this week in the journal Proceedings of the Royal Society B, showed the structure provided by kelp forests is more important than the food it produces.
Researchers analyzed the benefits of kelp forests using a complex computer model powered by real world data and observations collected over several decades. The model was designed to reflect the combination of variables affecting the interactions between kelp, herbivores and predators.
“We posited that giant kelp fed herbivores in the system and provided structure and habitat for predators, and that it was fed upon by sea urchins and affected the understory communities of algae and sessile invertebrates in the kelp forest,” Robert Miller, a research biologist in UCSB’s Marine Science Institute, said in a news release. “We found that the giant kelp affected some of these groups more than others.”
The research showed the presence of kelp boosts the diversity of predators found in an ecosystem, but depresses the abundance of understory algae — which in turn increases the survival odds of algal competitors like sponges and sea squirts.
While sea urchins, which eat kelp leaves, can have a small negative effect on kelp abundance, the models showed no other strong correlations between kelp and marine herbivores. Most herbivores eat a varied diet and as such have a minimal impact on kelp forests.
The data showed that, as Darwin predicted, kelp forests are ecologically valuable due to the unique habitat they create, not necessarily the sustenance they provide.
“Our modeling results suggest that the physical aspects of the kelp — its sheer size and its presence, the shade that it casts, its effect on flow and the habitat it provides for predators — affect the reef ecosystem more than its productivity,” Miller said. “Although kelp is clearly important as a food resource to some organisms on the reef, its structural effects are important and far reaching.”
