Freshwater Reefs
Table of Contents
Introduction
Most people think about standard coral when they think of reefs, but in some lakes and rivers there are remnants of ancient coral reefs which still provide habitat for aquatic life.
What Are Freshwater Reefs?
There are a variety of types of freshwater reefs including microbialites, rock piles, and other underwater structures for wildlife to use as feeding, breeding, and hiding spaces.
About This Page
This page explores some existing reefs, projects aimed to protect and restore them, as well as methods to create new freshwater reefs.
Types of Freshwater Reef
Fallen Trees
These are the most temporary type of freshwater reef. Trunks, branches, and twigs can help create vital spawning and hiding places for fish and other aquatic life. Some fish can't reproduce or find hiding places without adequate plant matter. Having a healthy ripparean area along side water ways and larger bodies of water can help keep water temperatures cooler and more stable. When trees die and become snags they help a wide range of species, then when they fall into the water, the provide a wide range of ecological services to animals above and below the water surface.
In modern times people have removed riparean buffer zones, which has increased water temperatures. The practice has also robbed water ways of vital habitat, but some
Microbialites
"Microbialites resemble coral reefs but can also be found in freshwater systems. Composed of sediments built up over many hundreds of years and multiple interactions between microorganisms such as diatoms and cyanobacteria and minerals, they can sequester carbon through a process called biologically-mediated carbonate precipitation, though just how this is done is still poorly understood. Some researchers think microbialites resemble structures that may have existed on Earth 450 million years ago, which could help them recognize signs of life on other planets.
By sequencing a handful of samples taken from several surface layers of an active, river-based microbialite in the Cuatro Cienegas Basin of Northern Mexico, researchers hope to learn more about the microbial communities that are associated with these structures and find out what roles they play in sequestering carbon. Learning more about the genomes of the microbial communities in the microbialite would not only provide more information about the role microbialites play in the global carbon cycle, which could prove crucial as carbon dioxide levels continue to rise, but could also be useful to researchers who work with stromatolites and other, similar structures which can also sequester carbon." - https://jgi.doe.gov/why-sequence-modern-freshwater-microbialites/
Microbialites: the Freshwater Reefs of Green Lake
1:50 minute video introducing these rare reefs found in freshwater lakes.
"Microbialites are part of the benthos, the bottom portion of marine and inland lake ecosystems, a previously overlooked component of aquatic food webs. Pelagic (open-water) organisms were previously thought to only feed on resources contained in the water column, but emerging research is pointing to the importance of benthic biofilm as a food source for these consumers (Vadeboncoeur and Power 2017). Therefore, microbialites and their productive biofilms highlight an emerging theme in ecology: unseen resources often contribute unexpectedly to the functioning of ecosystems we value and seek to protect. In fact, abundant biofilms contained on microbialites in marine and hypersaline ecosystems are likely an important food source for invertebrates (Lindsay et al. 2017, Rishworth et al. 2018)." - Microbialites are the Unseen Power House for Marine and Inland Sea Ecosystems
Further Reading About Microbialites
Rock Piles
Major Threats
The following are not listed in any particular order.
Acid Rain from livestock farming and industrial practices.
Fishing & Aquaculture
Ghost Nets can smother these natural resources and pose danger to the species who rely on lake reefs
Aquaculture waste: fish feces, antibiotics and other medications or poisons harm all aquatic life, but in particular fecal waste has been found to smother reefs which (unlike mobile lifeforms) can't swim, crawl, or float out of harms way.
Slaughterhouse/Meat Processor Waste pipes of blood and other disease-contaminated waste is dumped into waterways.
Sewage
Livestock Manure
Human & Pet Sewage
Invasive Species these can displace species, over eat and cause trophic cascade, bring disease, etc.
Rising Temperatures and Droughts
Sedimentation
Damage from Diving & Tourism
Oil & Chemical Spills
Coral Disease
Algae Blooms
Plastic & Other Aquatic Debris
Locations
North America
Canada
Pavilion Lake, British Columbia
Mexico
Bacalar Lagoon
USA
The Great Lakes including Lake Michigan
Great Salt Lake, Utah
Species Who Need Freshwater Reefs
Lake Herring
Lake Trout
Programs & Projects
North America
USA
Louisiana
Louisiana Artificial Reef Program "includes planning documents and reef locations"
Resources & Guides
How to Build a Freshwater Artificial Reef (PDF) This guide provides a variety of suggestions, but we caution strongly against using plastics including the used tires suggested in this document.
Tires and other plastics have been found to leach toxic chemicals into bodies of water, contaminating the food chain including the species we want to help. In the ocean tides and storms push tires around causing them to come apart and do serious damage to the ecosystems they are supposed to help. The popularity of using tires followed by the devastation they caused made many people skeptical about programs and organizations who built artificial reefs, but the mistake also gave data so that we can build safer, more successful reefs in the future.Microbialites are the Unseen Power House for Marine and Inland Sea Ecosystems gives a useful overview of where these ecosystems can be found, what they are made of, and how they fit into eco systems.
Oceana
Australia
Handbook for the Study and Description of Microbialites "Geological Survey of Western Australia (GSWA) Bulletin 147 formally standardises the terminology and approaches used in studying microbialites. Condensing nearly 50 years of research and practical experience into a single volume, the authors, Dr Kathleen Grey and Prof. Stanley Awramik, provide a comprehensive guide to the methods for describing and interpreting fossil and recent microbialites."
