I wondered if this paper is talking about the individuals, rather than the population. Read from the angle that this is about the ageing process of individuals, the paper began to make a bit more sense.
I could be totally wrong in this, but I think that copy errors have been used to explain the ageing process of individuals along with something about telomere length wich would give individuals a finite life span. The author gives the impression that the meadow of seagrass is a single individual, rather than a population. I did a search for this author to get an idea of her area of research, but I'm none the wiser, basically because I fell asleep
I'm like a bloody dormouse at this time of year.