The Key silverside (''Menidia conchorum'') is a species of

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

in the family Atherinopsidae. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the

Florida Keys The Florida Keys are a coral cay archipelago located off the southern coast of Florida, forming the southernmost part of the continental United States. They begin at the southeastern coast of the Florida peninsula, about south of Miami, and e ...

. The Key silverside is a distinct and unique species, endemic to the Florida Keys, proven morphologically and genetically distinct from nearby related species (O'Leary et al. 2016). The species is greatly reduced in number, and the ponded salt waters in the lower Florida Keys are being rapidly lost to

sea level rise Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cry ...

. The species itself harbors a unique genetic diversity and adaptive potential. Numerous observations and recent studies agree that managing key silversides as a separate management unit is necessary. It has been recently recommended for threatened status by the Florida Fish and Wildlife Conservation Commission. The species is a U.S.

National Marine Fisheries Service The National Marine Fisheries Service (NMFS), informally known as NOAA Fisheries, is a United States federal agency within the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) that is responsible for the stew ...

br>Species of Concern
Species of Concern are those species about which the U.S. Government's

National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...

, National Marine Fisheries Service, has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the U.S
Endangered Species Act
(ESA).

Species Description

Getter (1981) surveyed the entire chain of the Florida Keys in the late 1970s and determined that the Key silverside has a restricted distribution and is only found in lagoonal and ponded waters of the Florida Keys. These ponds and lagoons are a relatively rare and novel habitat shared by a community of fishes, many found nowhere else. The Key silverside is the smallest known species of ''

Menidia ''Menidia'' is a genus of Neotropical silversides native to freshwater, brackish and marine habitats along the Atlantic and Gulf of Mexico coasts of North America, ranging from the Gulf of Saint Lawrence in Canada to the Yucatán Peninsula in Mex ...

'', females reach 58 mm (standard length) and males 50 mm. While the Key silverside is closely related to (paraphyletic with) the Tidewater silverside (''Menidia peninsulae'') it is distinctly deeper bodied and yellow in color, restricted in range and habitat. It is also less cold-tolerant in lab situations.

Conservation

Sea-level rise has flooded many of the largest salt ponds that are now lagoonal and flushed with each tide. These fragmented series of isolated ponds were the key to the survival of the species. Historically, salt ponds and lagoons have been filled for development which has reduced available

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s through the loss of a number of

ponds A pond is an area filled with water, either natural or artificial, that is smaller than a lake. Defining them to be less than in area, less than deep, and with less than 30% emergent vegetation helps in distinguishing their ecology from th ...

and formerly occupied sites and ponded and lagoonal habitats.

Conservation Designations

Florida Fish and Wildlife Conservation Commission: Based on the finding of the Key silverside BRG and subsequent consultation with other FWC fish experts, staff recommends that the Key silverside (Menidia conchorum) be listed as a Threatened species because it met criteria for listing in accordance with rule 68A-27.0012, F.A.C.

Status Reviews

Research is underway by Dr. Charles D. Getter, who has studied the species since the 1970s for his doctoral dissertation (1981). Charles D. Getter. Ecology and survival of the Key silverside, Menidia conchorum, an atherinid fish endemic to the Florida Keys. Ph.D., University of Miami, Rosenstiel School of Marine and Atmospheric Sciences), now being updated with new data and readied for publication.

References

* Population genetics and geometric morphometrics of the key silverside, Menidia conchorum, a marine fish in a highly fragmented, inland habitat SJ O'Leary, CM Martinez, H Baumann, DL Abercrombie… - Bulletin of Marine Science, 2016 * Ecology and survival of the Key silverside, Menidia conchorum, an atherinid fish endemic to the Florida Keys. Ph.D., University of Miami, Rosenstiel School of Marine and Atmospheric Sciences. Charles D. Getter. 1981. Menidia Fish described in 1927 Fish of the United States Taxonomy articles created by Polbot Taxa named by Samuel Frederick Hildebrand Taxa named by Isaac Ginsburg {{Atheriniformes-stub