Blog # 446 Ospreys and Climate change

 

Ursula flying back to her nest, courtesy of Cindy Sedlacek.

Many amphibians, mammals, birds, and marine and freshwater fish migrate to more favorable habitats outside their normal ranges when pressured by climate changes. Our oceans and inland waterways are constantly mixing temperatures, chemistries, and nutrients, causing resident fish to adjust. Other more static aquatic organisms, confined to their environment, have no such opportunity and must adapt or die out.

Throughout the millennia, climate change has influenced global biodiversity and impacted the structure and function of natural ecosystems. Adapting to today’s climate changes and man’s influences on the environment is among the most serious challenges facing wildlife and the ecosystems they depend on. Since the life of Ospreys are intricately tied to the freshwater fish they eat, let us look at how fluctuating annual temperatures, precipitation, and weather patterns affects Osprey prey species in fresh water lakes in the Northeast.

Fish populations in Northeastern lakes are in a constant state of flux depending on the severity of the seasons, ice cover, water temperature, algal blooms, nutrient load, runoff, road salt, disease, acid rain, and a host of other factors. This month’s bass competition in Cayuga Lake had the top five fish averaging 5.5 pounds, showing that large-mouth bass populations are in good health in this Finger Lake.

The general effects of climate change on freshwater systems are increased water temperatures, decreased dissolved oxygen levels, increased evaporation, and increased toxicity of pollutants. In these systems, altered hydrologic regimes and warming groundwater temperatures also affect the quality of fish habitat and overall fish population. Unless the fish can adapt quickly or migrate, they will perish.

Fish physiology is inextricably linked to temperature, and fish have evolved to cope with specific hydrologic regimes and habitat niches. Therefore, their physiology and life histories will be affected by alterations induced by climate change. Range shifts will likely occur on a species level, and not on the community level, adding novel biotic pressures to these aquatic communities. Genetic changes are also possible and are      the only biological option for fish that are unable to migrate or acclimate to the changes. Endemic species, species in fragmented habitats, or those in east–west oriented systems will be less able to follow changing thermal isolines over time; some species of fish will not find new habitats and will go extinct.


A hot, ultra-saline pond in Death Valley, courtesy of Bruce Marcot.

Freshwater fish in particular have the unique challenge of either quickly adapting to varying temperatures and salinities or moving with the changing gradients. Such a range expansion is not always possible, forcing a genetic solution if possible.

The desert pupfish (Cyprinodon spp.), native to California and Nevada, is the master of adaptation. Pupfish can endure salinities ranging from freshwater to 68–70 parts per thousand (twice as salty as the ocean), water temperatures from 40 °F to 110° F, and oxygen levels down to 0.1 parts per million (ppm). Desert pupfish can also survive rapid changes in salinity, high levels of arsenic, often escape stressors by diving into the substrate. The secret to their success is their extreme adaptability, their genetic plasticity and multi-allelic haplotypes, which enable pupfish to thrive in an array of rapidly changing aquatic conditions. Despite this amazing genetic variation, the one thing pupfish cannot adapt to is the lack of water. They can survive buried in damp mud for several seasons, but not as a long-term strategy.


A warm, arsenic-laden pupfish pool in Death Valley, by Bruce Marcot.


The minute endangered desert pupfish in Death Valley, courtesy of Bruce Marcot.

The availability of fish is a priority for Ospreys. If their food source is cut off or suddenly dies off due to climate shifts, the Osprey must adapt quickly or perish. Typically, the fragile nestlings would starve, and the adults must migrate elsewhere to fish. The following year they might comeback to see if the fish have returned. If not, the Osprey will look for a new colony, a new food source, and new nest. This could alter food webs and habitats along the way.




Eyes to the sky!

Candace

Candace E. Cornell

Friends of Salt Point, Lansing, NY

Cayuga Lake Osprey Network cec222@gmail.com

 

EYES ON OSPREYS

WATCH!

Salt Point Osprey Nest Cam 2022

2023 footage also available

READ!

 On Osprey Time: Ospreys of the Finger Lakes

VISIT!

Cayuga Lake Osprey Trail Nests Driving Tour

Complete Cayuga Lake Osprey Trail

HELP PROTECT OSPREYS:

•Stay 300 feet away from nests during the breeding season. If the Osprey vocalizes, you are too close! Back off Immediately.

•Carry binoculars to view wildlife from afar.

•Help keep local waters clean, healthy, and safe.

•Recycle used fishing lines, twine, and nets, which can kill Osprey.

•Join the Cayuga Osprey Network and volunteer to help monitor Osprey nests: cec222@gmail.com.


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