all washed up, reproductively

From maritima

While walking to our field site at Mt. Hope Farm in Bristol, RI on Friday, we found this jelly-like egg mass washed up in the high intertidal. I don't know if it is indeed an egg mass or what type of organism it belongs to. The photos capture it fairly well - it was nearly two feet in diameter, and made of many translucent, nodular strings. Anyone have any ideas?

From maritima

marsh restoration in the Gulf of Mexico

Here is a photo of the type of wave protection being put on salt marsh restorations in the Gulf of Mexico, like the ones referred to in Rusty Feagin's comment. Thanks for the photo, Rusty!

plants vs. soil - a meaningless fight

Salt marshes and mangroves are reported to protect coasts from erosion and reduce storm surges. Salt marsh area has been correlated with reduced property damage from hurricanes along the Gulf Coast (Costanza et al. 2008, Ambio), and mangrove forest purportedly protected villages and reduced the death toll of a 1999 Indian cyclone (Das and Vincent 2009, PNAS).

However, a new study about to be published in Proceedings of the National Academy of Sciences (PNAS) reports that the soil, not the vegetation, in marshes is the important the feature preventing coastal erosion. The study, led by Rusty Feagin of Texas A&M, put large cores of marsh with and without vegetation in a wave tank and observed erosion patterns. Vegetation did not affect the rate of erosion, but sandy soils eroded more quickly than organic soils. The report questions the efficacy of salt marsh restorations that aim to prevent coastal erosion.

I look forward to reading the full publication. While I am sure it is a worthy scientific contribution, I think drawing conclusions about restoration efforts from these findings is misguided. The key about marshes is that they are biogenic - the organisms (in this case, plants) build the habitat. Were the plants not present, there would not be bare soil, but rather open water. Therefore, the idea of erosion protection from marsh soils without plants is nonsensical. Additionally, the key to maintaining the habitat is not erosion resistance, but sediment balance: how quickly sediment is added compared to the rate it is eroded. The plants likely act on the sediment addition end, even if they don't always contribute to the prevention of erosion (although they likely also do this in peaty soils, like in New England marshes). Finally, the coastal protection value of marshes comes from erosion prevention AND wave attenuation. In models, it is mostly the wave attenuation process that affords coastal protection from storms.

You can read a brief about the article published online at Nature.

Spring means unkempt lawns

As any New Englander will tell you, spring is much better after a long winter. Everything comes back to life, and that includes the weeds. I love lawns this time of year, before people rouse their lawnmowers. The weeds grow tall and in rosettes, and flower and seed - a suburban tallgrass prairie. A few photos from my pedestrian commute:

Bizarro Fungus

When my friend Andrew Altieri pointed out this bizarro structure in the cedar trees at Hundred Acre Cove in Barrington, RI, we had trouble even identifying it to the plant or animal kingdom. Prof. Doug Morse, at Brown, who has helped me identify strange maritima creatures in the past, helped us place it - in the Fungi kingdom...We should have guessed it. Fungi is a happy home for many weirdos that have never fit neatly into plant or animal designations.

Our mystery organism is a cedar apple rust, Gymnosporangium juniperi-virginianae, a fungus that spends part of its life cycle in red cedars, and the other half in apple or crab apple trees, to which it does much more damage. This time of year, during the spring rains, the rust's woody galls on cedar branches begin producing these bright orange telial horns which contain the spores that will infect young apple leaves later this growing season. You can see more info on the cedar apple rust, found at least as far as Texas, here and download a fact sheet here.

like sesame seeds in a sandbox

Field season has not yet truly begun here in New England (we're still anxiously awaiting budburst!), but I have been spending some time in the field, investigating barnacle recruitment in Narragansett Bay. Here, the intertidal barnacle Semibalanus balanoides reproduces in the fall and broods its larvae until the winter. Larvae are released in January and develop in the water column for about a month and begin to settle in February and March. They settle as cyprids, a larval stage that looks an awful lot like a sesame seed (see photos). In the cyprid stage, the barnacles decide where on the shore to settle and attach, based on chemical cues from adult barnacles and surface texture. This is a critical moment in a barnacle's life - after metamorphosis, it will be stuck in the same place for the rest of its sessile adult life.

Click here for full size photos.

Mangrove restoration suggestion

My collaborator, Brian Silliman, and I published a comment this month in the British scientific journal Ambio about incorporating into mangrove restoration design plans the natural capacity of wetland plants to reduce environmental stress for them and their neighbors . Here is an excerpt (references omitted):

Using Facilitation Theory to Enhance Mangrove Restoration

Most mangrove restorations around the world, including the Philippines example, plant mangroves as single seedlings, evenly spaced, in rows. This configuration is based on the assumption that competition among seedlings needs to be minimized to foster establishment and growth. Thus seedlings need to be spaced well away from each other to maximize light availability and minimize competition between neighbors. However, whereas light availability can be a limiting factor at later stages in mangrove forest development, the limiting growth factors at the initial stages of mangrove establishment are edaphic stressors, such as low redox potential and high soil salinity, as recognized by the Samson and Rollon. Because coastal wetland plants engineer the substrate to ameliorate these harmful conditions, an effect that increases with wetland plant density, seedlings are likely to exhibit positive, not negative, density dependence because of the facilitative effects of neighbors on ameliorating anoxic soil conditions.

Ecological theory and wetland experiments both predict that mangrove seedlings have a far better chance of survival if they are planted in clusters of several seedlings rather than plantation style. Planting seedlings in clusters will likely allow the necessary positive feedbacks to take root in the absence of adult plant roots or pneumatophores. For example, a black mangrove restoration in Mexico that planted five-seedling clusters resulted in notably high survival of planted seedlings (74%) after 4 years, despite being planted in a mudflat environment. Mangrove seedlings frequently suffer high rates of mortality, and clustered or redundant plantings allow surviving seedlings to compensate for lost neighbors. Nurse plants, which can serve the same purpose in a restoration as seedling clusters, promoting the facilitative species interactions that ameliorate abiotic stress, have also been found to improve mangrove restoration success. Higher plant densities have also been found to reduce herbivory on susceptible, young plants in other saline wetland environments.