Monday, October 5, 2015

Feast or Famine: Drought or Flood

By Beth Sullivan
Conditions have been so terribly dry. Trees are dying; leaves are browning. Many plants seem to be succumbing or going into early dormancy. We have all been wishing for rain. The saying is: “ Be careful what you wish for…..”
Water floods and nourishes the salt marsh.

As I write this (Sept.30) we are wringing out from over 4.5 inches of rain for just today and now thinking to a hurricane impacting our weekend. While the plants seem so be grateful for the rinsing, we all hope the water has had a chance to soak in and be conserved, rather than flow off the terribly dry soil and too quickly flood the small streams ending up out in the sound. When water runs off that quickly, it takes along chemicals and pollutants from lawns, roads and many other sources, which requires closure of shellfish beds or swimming areas. A lovely long soaking rain is much more beneficial for all.

Super full moon raises tides

We are also just past the super full moon which brought extra high tides. During these phases of the moon when it is closest to the Earth and exerts its greatest pull on our oceans, the tides rise and fall with the greatest of extremes. Those of us lucky enough to live near the coast, and keep an eye on such things, are quick to notice how “full” everything feels during these high tides. It is almost like the entire surface of our landscape is riding higher.
High tides and flooding rains have filled Dodge Paddock and Beal Preserve.

These tides bring great nourishment to the salt marshes. Many areas are only bathed in salt during the highest of tides. The waters bring nutrients that are necessary to support the marsh grasses. The tides bring in sediments and organic material so the grasses can capture them and let them remain at their roots. It is how marshes are built. The highest tides also bring in small bits of ocean life, from the planktons, and small invertebrates to fish.
During the dry times, the marsh dries and cracks.

Killifish are the fish of the marshes

They ride the currents and swim into the shallows and into the grasses. They tolerate a wide range of salinity from nearly fresh water to pure ocean water. When they arrive in the marshes with the flooding tide, they feed on the small creatures including mosquito larvae that have been thriving in the shallow pools on the marsh. When the waters recede, sometimes the Killifish remain behind in ditches and pools. They can survive the changing conditions, and even low oxygen in the water, until the next high tide flows in to refresh or release them.
Killfish are tolerant of changing water conditions, fresh or salt and thrive in the flood.

Mussels line the banks and edges of the marsh and rely on the high tidal flushing to deliver nutrients, food, directly to them as of course they cannot move. Fiddler crabs will burrow deeply while the tides run high, but when the tide goes out, huge swaths of mudflats are exposed, providing them a banquet that they have waited for.
At low tide, Fiddler crabs by the thousands emerge to scavenge the mudflats.

Holes in the marsh edges, exposed at lower tides, house mussels and crabs.

The high tides bring the salts, and the flooding rain brings the fresh water. Both mix and flow to create the unique ecosystems we know along our shoreline. It is all about balance. Now we wait to see if a Hurricane might mix things up again.
Newly planted Spartina grasses are holding on int the flood.

Photographs by Beth Sullivan.

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