Data from: Broad-scale geographic variation in the organization of rocky intertidal communities in the Gulf of Maine

A major challenge facing ecology is to better understand how large-scale
processes modify local scale processes to shape the organization of
ecological communities. Although the results of ecological experiments are
repeatable on local scales, different results often emerge across broad
scales, which can hinder the development of general predictions that apply
across the geographical range of a community. Numerous studies in the
southern Gulf of Maine have shaped our understanding of community
organization and dynamics on New England rocky intertidal shores, where
consumers strongly control recovery from disturbance on sheltered shores
and high invertebrate recruitment and competition for space dictate
recovery on wave-exposed shores. It is unclear, however, whether the
effects of consumers and recruitment variation on resulting community
organization in this region apply more broadly to rocky intertidal
habitats throughout the Gulf. We characterized variation in rocky
intertidal community structure at 34 sites throughout the Gulf of Maine
and experimentally examined the influence of consumers (present, absent)
and wave energy (wave-exposed, sheltered) on community recovery from
disturbance in the northern and southern Gulf. Our results reinforced
previous work in the southern Gulf because consumers dictated the recovery
of fucoid algae and mussels on sheltered shores, whereas high barnacle and
mussel recruitment and competition for space shaped recovery on
wave-exposed shores. However, on sheltered shores in the northern Gulf,
neither consumers nor barnacle and mussel recruitment impacted recovery,
which was dominated by fucoid algae. Moreover, recovery on wave-exposed
shores in the northern Gulf was quite distinct from that observed in the
southern Gulf: barnacle and mussel recruitment was negligible and fucoid
algae dominated recovery including the long-term establishment of
Ascophyllum nodosum, which is largely absent from wave-exposed shores in
the southern Gulf. Thus, distinct community types emerged in the northern
and southern Gulf despite their sharing many of the same species. These
patterns likely emerged because of regional differences in coastal
oceanography that dictate the recruitment of barnacles and mussels. Hence,
increased attention to regional factors should provide key insight into
how rocky shore communities are organized in the Gulf of Maine and
elsewhere.