DRAFTING…
There have been large losses of seagrass beds throughout the tropical Atlantic and as for coral reefs, increasing attention is being given to restoration efforts. For seagrasses, those rely on an understanding of the growth, production and population dynamics of the seagrasses.
Growth & Productivity – Barbados based research
– The origin of nitrogen and phosphorus for growth of the marine angiosperm Thalassia testudinum
Patriquin, D.G. 1972. Marine Biology 15: 35-46. PDF “How are high rates of production by Thalassia testudinum König maintained in notably nutrient-poor tropical waters? Yield-nutrient supply correlations indicate that a singnificant proportion of the phosphorus, and virtually all nitrogen for leaf growth are taken-up from the sediments, and that growth is generally limited by availability of nitrogen. Considerations of supply and demand suggest that the sediments could not be a primary source of phosphate, but the sediments may act as a “storage bank” for phosphate taken up from the sea water by T. testudinum. It is believed that inorganic nitrogen in the root layer is derived from fixation of gaseous nitrogen by anaerobic bacteria. Maintenance of anaerobic conditions in the root layer appears to be essential for good growth of T. testudinum, and it is suggested that such conditions facilitate nitrogen fixation.”
– Nitrogen fixation in the rhizosphere of marine angiosperms
Patriquin, D.G. and R. Knowles. 1972. Marine Biology 16: 49-58.“High rates of acetylene reduction were observed in systems containing excised rhizomes of the Caribbean marine angiosperms Thalassia testudinum, Syringodium filiforme and Diplanthera wrightii, and the temperate marine angiosperm Zostera marina. For 4 plant and plant-sediment systems the ratio of acetylene reduced/N2 fixed varied from 2.6 to 4.6. For T. testudinum the estimated rates of nitrogen fixation are in agreement with estimated requirements of the plant for nitrogen.”
– Estimation of growth rate, production and age of the marine angiosperm Thalassia testudinum König
David G Patriquin, 1973. Caribbean Journal of Science 13: 111−123 “There is a linear relation between average growth rate and the average maximum leaf length of Thalassia stands. The ratio production-to-standing crop (wet weight including epiphytes) tends to be constant. New foliage leaves are developed at intervals of about 15 days, and by counting of leaf scars, the age, growth rate and production of underground parts can be estimated.”
– Effects of shoot age on leaf growth in the seagrass Thalassia testudinum in Barbados
LA Vermeer & Wayne Hunte 2008. Aquatic Biology 2(2):153-160 “: Effects of shoot age on leaf growth variables of Thalassia testudinum were investigated in St. Lawrence Bay, Barbados…Results from 2 previous studies and the results of the present study suggest that shoot age effects on leaf growth variables may be common in seagrasses, and that shoot age may have been largely overlooked as a component of the spatial and temporal variation in leaf growth typically observed in seagrasses.”
Growth & Productivity – some key papers
Seagrass Dynamics – some key papers
– Dynamics of Seagrass Stability and Change
by Duarte, C.M., Fourqurean, J.W., Krause-Jensen, D., Olesen, B. (2007).
In Seagrasses: Biology, Ecology and Conservation, edited by Anthony W.D. Larkum, Robert J. Orth and Carlos M. Duarte. Springer
Duarte et al., describe how one can predict seagrass population dynamics using shoot demography and apply the techniques to understand/predicting seagrass patch and gap dynamics. The technique rests on the determination of the “Plastochrone Interval” “It is possible to estimate the age of individual shoots of most seagrass species because there is a relatively constant rate of production of new leaves on a shoot, called the plastochron interval. Each leaf leaves a distinctive scar on the short shoot at the node, so it is possible to count the number of leaves produced over the lifespan of an excavated shoot and multiply this number of leaves by the plastochron interval to estimate the age of the shoot (Patriquin, 1973; Duarte et al., 1994). Once recruited into the population, shoots of different species have different average lifespans.”
– Reconstruction of seagrass dynamics: age determinations and associated tools for the seagrass ecologist, Carlos M. Duarte et al., 1994. in Marine Ecology Progress Series. “….Techniques based on age determinations have been used since, alone or in combination with standard marking techniques, to reconstruct different aspects of seagrass ecology.”
Seagrass Restoration
– A successful method to restore seagrass habitats in coastal areas affected by consecutive natural events
Claudia Patricia Ruiz-Diaz et al., 2024 in PeerJ 12:e16700 DOI 10.7717/peerj.16700
The article provides a concise overview of the state of seagrass restoration efforts in the Tropical Atlantic as well as the methods and results of recent restoartion efforts in Puerto Rico.