Ecological extinction caused by overfishing precedes all other pervasive human disturbance to coastal ecosystems, including pollution, degradation of water quality, and anthropogenic climate change. Historical abundances of large consumer species were fantastically large in comparison with recent observations. Paleoecological, archaeological, and historical data show that time lags of decades to centuries occurred between the onset of overfishing and consequent changes in ecological communities, because unfished species of similar trophic level assumed the ecological roles of overfished species until they too were overfished or died of epidemic diseases related to overcrowding. Retrospective data not only help to clarify underlying causes and rates of ecological change, but they also demonstrate achievable goals for restoration and management of coastal ecosystems that could not even be contemplated based on the limited perspective of recent observations alone.

Humans transformed Western Atlantic coastal marine ecosystems before modern ecological investigations began. Paleoecological, archeological, and historical reconstructions demonstrate incredible losses of large vertebrates and oysters from the entire Atlantic coast. Untold millions of large fishes, sharks, sea turtles, and manatees were removed from the Caribbean in the 17th to 19th centuries. Recent collapses of reef corals and seagrasses are due ultimately to losses of these large consumers as much as to more recent changes in climate, eutrophication, or outbreaks of disease. Overfishing in the 19th century reduced vast beds of oysters in Chesapeake Bay and other estuaries to a few percent of pristine abundances and promoted eutrophication. Mechanized harvesting of bottom fishes like cod set off a series of trophic cascades that eliminated kelp forests and then brought them back again as fishers fished their way down food webs to small invertebrates. Lastly, but most pervasively, mechanized harvesting of the entire continental shelf decimated large, long-lived fishes and destroyed three-dimensional habitats built up by sessile corals, bryozoans, and sponges. The universal pattern of losses demonstrates that no coastal ecosystem is pristine and few wild fisheries are sustainable along the entire Western Atlantic coast. Reconstructions of ecosystems lost only a century or two ago demonstrate attainable goals of establishing large and effective marine reserves if society is willing to pay the costs. Historical reconstructions provide a new scientific framework for manipulative experiments at the ecosystem scale to explore the feasibility and benefits of protection of our living coastal resources.

The increase in oceanic biodiversity over the past half billion years is poorly understood despite the great importance of the pattern for understanding the history of life. Compilations of genera from the paleontological literature for the entire Phanerozoic (~540 million years) include only half the number of fossilizable taxa that occur in the oceans today, and the data are highly variable in quality. In their Perspective, Jackson and Johnson argue that a limited number of intensive and consistent sampling projects could maximize our understanding of the overall pattern and trends in past marine biodiversity.

Cycles in environmental conditions (e.g., sea-surface temperature) directly impact fish growth. This paper extends the classical Gordon-Schaefer fishery model by replacing the constant growth rate with a cyclical growth rate. The optimal harvest rate is shown to fluctuate, but the cycle of the harvest rate lags the cycle of the biological growth function with the highest harvest rate occurring after biological conditions start to decline. Simulations contrast various fishing policies and illustrate the proclivity to crash a fishery if it is wrongfully managed as if there is a constant growth rate with i.i.d. environmental shocks. Finally, we show that small cyclical fluctuations in one species can result in large fluctuations in the optimal harvest rate of another species if the fish species are interlinked through predator-prey relationships.

Metrarabdotos Canu, 1914 and the related genera Escharoides Milne Edwards, 1836b, Adeonellopsis MacGillivray, 1886, and Reptadeonella Busk, 1884 were key taxa in the decline of Bryozoa with erect, arborescent colonies and concomitant increase in numbers of species with encrusting colonies in the late Paleogene and Neogene of tropical America. In particular, the abundance, continuity of occurrence, and diversity of Metrarabdotos before its decline have made this genus, over the past 20 years, a model taxon for detailed morphometric studies of fine-scale evolutionary tempo and mode. During the same period, significant new occurrences of both Metrarabdotos and its near relatives have been documented with detailed collections from tropical American areas not represented in the original studies. In this paper we present a complete reanalysis of the original morphometric data (Cheetham, 1986a), incorporating the new tropical American material and comparative material of selected Metrarabdotos species from Europe and Africa in order to formalize the taxonomy of the genus, many species of which have been in open nomenclature since 1986, and to explore their possible phylogenetic relationships to each other and to Escharoides, Adeonellopsis, and Reptadeonella. The new analysis, with procedures slightly modified from those used in the original analysis, is based on more than twice the number of specimens and 20% more morphological characters. Although the results include changes in species assignments for 13% of the specimens in the original analysis, the pattern of intraspecific morphological stasis previously identified in the tropical American Neogene species, and thus the concomitant interpretation of evolutionary tempo and mode, are unaltered. Cladistic analysis resulted in a single most parsimonious tree for the 22 tropical American Metrarabdotos species, arranged in two monophyletic crown groups and a paraphyletic stem group. The stem group, ranging from latest Eocene to late Early or early Middle Miocene in age, includes four species, two of which are new: M. aguilerai from Venezuela and M. hispaniolae from the Dominican Republic and Haiti. Crown group A comprises seven species occurring in deposits of Late Miocene to Recent age, four of which are new: M. arawakorum from Venezuela; M. boldi and M. saundersi from the Dominican Republic; and M. coatesi, which occurs in the Dominican Republic, Costa Rica, and Panama. Crown group B, comprising 11 species, ranges from Early Miocene to Recent and includes five new species: M. cubaguaense from Venezuela; M. vokesorum from the Dominican Republic, Costa Rica, and Panama; and M. tainorum, M. jungi, and M. lopezense from the Dominican Republic. Incorporation of six European and African (eastern Atlantic) species, ranging in age from Early Miocene to Recent, into cladograms with the tropical American species produced more variable results in terms of both numbers of alternative trees and the positions of the tropical American species in them. One of these species, M. thomseni from the Pleistocene of Greece, and possibly a second, M. cf. M. maleckii Cheetham, 1968 from the Miocene of the Czech Republic, are new. With one exception, the eastern Atlantic species were placed in more or less basal positions in one or the other of the crown groups, suggesting that, as hypothesized by Cheetham (1968), the “Old World” and “New World” species of Metrarabdotos represent largely independent radiations. The exception is the living species M. cookae Cheetham, 1968, from West Africa and the Cape Verde Islands, which is placed unequivocally in a terminal position in crown group B. Although the three groups of tropical American species correspond in part to subgenera of Metrarabdotos erected by Cheetham (1968), the paraphyly of the stem group and the unresolved identity of the type species of the subgenus apparently corresponding to crown group A suggest that formalizing the taxonomy of these groups is unwarranted at present. A further cladistic analysis, incorporating the three groups of Metrarabdotos species and Escharoides, Adeonellopsis, and Reptadeonella, yielded two trees, both of which support Cheetham's (1968) hypothesis that Metrarabdotos is more closely related to Escharoides than to Adeonellopsis and Reptadeonella. Escharoides is represented in tropical American Neogene deposits by two species, one of which, E. guraboensis from the Dominican Republic, is new. Of the six tropical American Neogene species of Adeonellopsis, four are new: A. cribrospiramen and A. guraboensis from the Dominican Republic, A. limonensis from Costa Rica, and A. antilleana from Cuba and Jamaica. Three of the six tropical American Neogene species of Reptadeonella, R. buddae from the Dominican Republic, R. collinsae from the Dominican Republic, Panama, Costa Rica, and the southeastern United States, and R. buricaensis from Panama, are also new.

Three new Miocene-Pliocene species of the cheilostome bryozoan Metrarabdotos from Venezuela are atypical in showing significant evidence that as many as half the colonies originated asexually (clonally) by “regeneration” from previously existing colonies, rather than almost exclusively from ancestrular zooids (products of metamorphosis of sexually produced larvae), as is characteristic of the genus. The extremely low proportion of zooids (less than two percent) recognizably committed to producing larvae (ovicelled) in these Venezuelan species agrees with that reported in a variety of Danian (Paleocene) genera in which clonal propagation has been reported to predominate. However, all but two of 17 other living and fossil species of Metrarabdotos also have fewer than two percent of their zooids ovicelled, even though all but one of more than 250 colony bases examined originated from ancestrulae. The lack of significant correlation in Metrarabdotos between frequencies of ovicelled zooids and of ancestrular colonies suggests that clonal propagation may not have diverted resources from sexual reproduction. This inference is supported by the retention in these species of a level of heritable morphologic variation (estimated by partitioning among-colonies and within-colonies variance in zooid characters) that is commensurate with that estimated for species of Metrarabdotos in which propagation was apparently entirely by sexual means. Thus, sexual reproduction throughout the genus was apparently sufficient to maintain the genetic diversity from which speciation could proceed at normal rates. As estimated by both cladistic and nearest-neighbor morphologic-stratigraphic methods, the three Venezuelan species occupy quite different positions in the inferred phylogeny of Metrarabdotos. Thus, the elevated level of clonal propagation in these species appears to be a response to local conditions, most probably high productivity associated with upwelling, that promoted more rapid vegetative growth while leaving the level of sexual reproduction unchanged.