Then and Now

The Greek philosopher Heraclitus, who lived from 535-475 BC, said "Nothing endures but change." In an ecological sense these words ring true, especially in the coastal ocean where natural and human disturbance impact habitats and communities of organisms. In Long Island Sound, we find some habitats and communities are extremely stable while others change after small to large disturbances. Even stable communities have some variation in the numbers of particular species, some changing their level of dominance over time. Another way to look at the issue of change and disturbance is that some species in some habitats will go through a predictable sequence of community types before reaching a mature or "climax" community. This same type of sequence happens in the recovery of old farm fields to mature forest here in Connecticut. However, other communities do not respond in this manner. They respond in more of a lottery fashion that, after some threshold of disturbance is reached, the community switches to another unpredictable type that can remain stable until another threshold is reached, and so on. While limited to the species that are available to recruit to disturbed habitats, there is no real succession back to a climax community.

Here we show how some communities remain stable, or shift in composition, over time. Time scales too vary in their significance, with some habitats changing over a tidal cycle and others remaining relatively stable over decades. We will be adding sets of images to our library here over time, to show contrasts in our underwater landscape then and now.

Fishers Island Sound off Latimer Reef

The seafloor community on a deep gravel pavement at 100 ft depth was composed of boring sponge, star coral, and purple urchins back in March 1987.

In May 2006, the community was dominated by an invasive colonial tunicate (Didemnum sp.).

Six-Mile Reef

Sand wave habitats at Six-Mile Reef off of the Connecticut River shift in form, based on the direction of water flow, over the change of a tidal cycle. These images are from underwater video during a dive in October 2006. Note the shift direction of the sand wave crests and the direction of the juvenile scup pointed into the flow. The shift in sand wave structure occurred within 30 minutes of the change in direction of the strong tidal current.

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