Jon M. Erlandson

Kelp forest ecosystems: biodiversity, stability, resilience and future

Kelp forests are phyletically diverse, structurally complex and highly productive components of coldwater rocky marine coastlines. This paper reviews the conditions in which kelp forests develop globally and where, why and at what rate they become deforested. The ecology and long archaeological history of kelp forests are examined through case studies from southern California, the Aleutian Islands and the western North Atlantic, well-studied locations that represent the widest possible range in kelp forest biodiversity. Global distribution of kelp forests is physiologically constrained by light at high latitudes and by nutrients, warm temperatures and other macrophytes at low latitudes. Within mid-latitude belts (roughly 40–60° latitude in both hemispheres) well-developed kelp forests are most threatened by herbivory, usually from sea urchins. Overfishing and extirpation of highly valued vertebrate apex predators often triggered herbivore population increases, leading to widespread kelp deforestation. Such deforestations have the most profound and lasting impacts on species-depauperate systems, such as those in Alaska and the western North Atlantic. Globally urchin-induced deforestation has been increasing over the past 2–3 decades. Continued fishing down of coastal food webs has resulted in shifting harvesting targets from apex predators to their invertebrate prey, including kelp-grazing herbivores. The recent global expansion of sea urchin harvesting has led to the widespread extirpation of this herbivore, and kelp forests have returned in some locations but, for the first time, these forests are devoid of vertebrate apex predators. In the western North Atlantic, large predatory crabs have recently filled this void and they have become the new apex predator in this system. Similar shifts from fish- to crab-dominance may have occurred in coastal zones of the United Kingdom and Japan, where large predatory finfish were extirpated long ago. Three North American case studies of kelp forests were examined to determine their long history with humans and project the status of future kelp forests to the year 2025. Fishing impacts on kelp forest systems have been both profound and much longer in duration than previously thought. Archaeological data suggest that coastal peoples exploited kelp forest organisms for thousands of years, occasionally resulting in localized losses of apex predators, outbreaks of sea urchin populations and probably small-scale deforestation. Over the past two centuries, commercial exploitation for export led to the extirpation of sea urchin predators, such as the sea otter in the North Pacific and predatory fishes like the cod in the North Atlantic. The large-scale removal of predators for export markets increased sea urchin abundances and promoted the decline of kelp forests over vast areas. Despite southern California having one of the longest known associations with coastal kelp forests, widespread deforestation is rare. It is possible that functional redundancies among predators and herbivores make this most diverse system most stable. Such biodiverse kelp forests may also resist invasion from non-native species. In the species-depauperate western North Atlantic, introduced algal competitors carpet the benthos and threaten future kelp dominance. There, other non-native herbivores and predators have become established and dominant components of this system. Climate changes have had measurable impacts on kelp forest ecosystems and efforts to control the emission of greenhouse gasses should be a global priority. However, overfishing appears to be the greatest manageable threat to kelp forest ecosystems over the 2025 time horizon. Management should focus on minimizing fishing impacts and restoring populations of functionally important species in these systems.

The Archaeology of Aquatic Adaptations: Paradigms for a New Millennium

Although aquatic resources are often seen as central to the development of post-Pleistocene cultural complexity, most models of human evolution have all but ignored the role of aquatic or maritime adaptations during the earlier stages of human history. When did aquatic resources, maritime adaptations, and seafaring first play a significant role in human evolution? I explore this fundamental question by (1) reviewing various theories on the subject; (2) discussing a variety of problems that prevent archaeologists from providing a clear answer; and (3) examining the archaeological record for evidence of early aquatic resource use or seafaring. I conclude that aquatic resources, wherever they were both abundant and relatively accessible, have probably always been used opportunistically by our ancestors. Evidence suggests, however, that aquatic and maritime adaptations (including seafaring) played a significantly greater role in the demographic and geographic expansion of anatomically modern humans after about 150,000 years ago. Another significant expansion occurred somewhat later in time, with the development of more sophisticated seafaring, fishing, and marine hunting technologies.

Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling

A carbon-rich black layer, dating to ≈12.9 ka, has been previously identified at ≈50 Clovis-age sites across North America and appears contemporaneous with the abrupt onset of Younger Dryas (YD) cooling. The in situ bones of extinct Pleistocene megafauna, along with Clovis tool assemblages, occur below this black layer but not within or above it. Causes for the extinctions, YD cooling, and termination of Clovis culture have long been controversial. In this paper, we provide evidence for an extraterrestrial (ET) impact event at ≅12.9 ka, which we hypothesize caused abrupt environmental changes that contributed to YD cooling, major ecological reorganization, broad-scale extinctions, and rapid human behavioral shifts at the end of the Clovis Period. Clovis-age sites in North American are overlain by a thin, discrete layer with varying peak abundances of (i) magnetic grains with iridium, (ii) magnetic microspherules, (iii) charcoal, (iv) soot, (v) carbon spherules, (vi) glass-like carbon containing nanodiamonds, and (vii) fullerenes with ET helium, all of which are evidence for an ET impact and associated biomass burning at ≈12.9 ka. This layer also extends throughout at least 15 Carolina Bays, which are unique, elliptical depressions, oriented to the northwest across the Atlantic Coastal Plain. We propose that one or more large, low-density ET objects exploded over northern North America, partially destabilizing the Laurentide Ice Sheet and triggering YD cooling. The shock wave, thermal pulse, and event-related environmental effects (e.g., extensive biomass burning and food limitations) contributed to end-Pleistocene megafaunal extinctions and adaptive shifts among PaleoAmericans in North America.

Early Hunter-Gatherers of the California Coast

Californias Coastal HunterGatherers: A Theoretical Perspective. Environmental Setting. Culture History. Research Procedures. Investigations at SBA-1807. Investigations at SBA-2061. Investigations at SBA-2057. Early Holocene Adaptations of the Santa Barbara Channel. Early Holocene Cultural Ecology on the California Coast. Summary and Conclusions. Index.

Paleoindian Seafaring, Maritime Technologies, and Coastal Foraging on California’s Channel Islands

Archaeological sites reveal a variety of tools used to hunt marine birds, mammals, and fish 12,000 years ago. Three archaeological sites on California’s Channel Islands show that Paleoindians relied heavily on marine resources. The Paleocoastal sites, dated between ~12,200 and 11,200 years ago, contain numerous stemmed projectile points and crescents associated with a variety of marine and aquatic faunal remains. At site CA-SRI-512 on Santa Rosa Island, Paleocoastal peoples used such tools to capture geese, cormorants, and other birds, along with marine mammals and finfish. At Cardwell Bluffs on San Miguel Island, Paleocoastal peoples collected local chert cobbles, worked them into bifaces and projectile points, and discarded thousands of marine shells. With bifacial technologies similar to those seen in Western Pluvial Lakes Tradition assemblages of western North America, the sites provide evidence for seafaring and island colonization by Paleoindians with a diversified maritime economy.

An archaeological and paleontological chronology for Daisy Cave (CA-SMI-261), San Miguel Island, California.

We provide detailed contextual information on 25 14 C dates for unusually well-preserved archaeological and paleontological remains from Daisy Cave. Paleontological materials, including faunal and floral remains, have been recovered from deposits spanning roughly the past 16,000 yr, while archaeological materials date back to ca. 10,500 BP. Multidisciplinary investigations at the site provide a detailed record of environmental and cultural changes on San Miguel Island during this time period. This record includes evidence for the local or regional extinction of a number of animal species, as well as some of the earliest evidence for the human use of boats and other maritime activities in the Americas. Data from Daisy Cave contribute to a growing body of evidence that Paleoindians had adapted to a wide variety of New World environments prior to 10,000 PB. Analysis of shell-charcoal pairs, along with isotopic analysis of associated marine shells, supports the general validity of marine shell dating, but also provides evidence for temporal fluctuations in the reservoir effect within the Santa Barbara Channel region.

The kelp highway hypothesis: marine ecology, the coastal migration theory, and the peopling of the Americas

ABSTRACT In this article, a collaborative effort between archaeologists and marine ecologists, we discuss the role kelp forest ecosystems may have played in facilitating the movement of maritime peoples from Asia to the Americas near the end of the Pleistocene. Growing in cool nearshore waters along rocky coastlines, kelp forests offer some of the most productive habitats on earth, with high primary productivity, magnified secondary productivity, and three-dimensional habitat supporting a diverse array of marine organisms. Today, extensive kelp forests are found around the North Pacific from Japan to Baja California. After a break in the tropics—where nearshore mangrove forests and coral reefs are highly productive—kelp forests are also found along the Andean Coast of South America. These Pacific Rim kelp forests support or shelter a wealth of shellfish, fish, marine mammals, seabirds, and seaweeds, resources heavily used historically by coastal peoples. By about 16,000 years ago, the North Pacific Coast offered a linear migration route, essentially unobstructed and entirely at sea level, from northeast Asia into the Americas. Recent reconstructions suggest that rising sea levels early in the postglacial created a highly convoluted and island-rich coast along Beringias southern shore, conditions highly favorable to maritime hunter-gatherers. Along with the terrestrial resources available in adjacent landscapes, kelp forests and other nearshore habitats sheltered similar suites of food resources that required minimal adaptive adjustments for migrating coastal peoples. With reduced wave energy, holdfasts for boats, and productive fishing, these linear kelp forest ecosystems may have provided a kind of “kelp highway” for early maritime peoples colonizing the New World.

The Role of Shellfish in Prehistoric Economies: A Protein Perspective

In many prehistoric economies where plant foods supplied a majority of caloric requirements, shellfish may have served as a protein staple, at least on a seasonal basis. This hypothesis is supported with an archaeological example from coastal California, experimental data on shellfish protein yields in southeast Alaska, and review of two previous studies of the economics of shellfish exploitation (Osborn 1977; Parmalee and Klippel 1974). Evaluating the dietary role of shellfish from a protein perspective may have a profound effect on the reconstruction of settlement and subsistence strategies for coastal, riverine, or lacustrine economies, including both hunter-gatherers and agriculturalists.

Oceans, Islands, and Coasts: Current Perspectives on the Role of the Sea in Human Prehistory

ABSTRACT Archaeological studies of island and coastal societies have advanced significantly over the years. Long marginalized as relatively recent developments, coastal, maritime, and island adaptations are now recognized as having a much longer and more complex history. Consequently, the archaeology of island and coastal societies has become increasingly relevant to a variety of important anthropological and historical topics. In this paper, we discuss some current issues in island and coastal archaeology, including: (1) the antiquity of coastal adaptations and maritime migrations; (2) variations in marine or coastal productivity; (3) the development of specialized maritime technologies and capabilities; (4) underwater archaeology and drowned terrestrial landscapes; (5) cultural responses to insularity, isolation, and circumscription; (6) cultural contacts and historical processes; (7) human impacts and historical ecology in island and coastal ecosystems; and (8) the conservation and management of island and coastal sites.

Paleocoastal marine fishing on the Pacific coast of the Americas: Perspectives from Daisy Cave, California

Analysis of over 27,000 fish bones from strata at Daisy Cave dated between about 11,500 and 8500 cal B.P. suggests that early Channel Islanders fished relatively intensively in a variety of habitats using a number of distinct technologies, including boats and the earliest evidence for hook-and-line fishing on the Pacific Coast of the Americas. The abundance of fish remains and fishing-related artifacts supports dietary reconstructions that suggest fish provided more than 50 percent of the edible meat represented in faunal samples from the early Holocene site strata. The abundance and economic importance of fish at Daisy Cave, unprecedented among early sites along the Pacific Coast of North America, suggest that early maritime capabilities on the Channel Islands were both more advanced and more variable than previously believed. When combined with a survey of fish remains from several other early Pacific Coast sites, these data suggest that early New World peoples effectively used watercraft, captured a diverse array of fish, and exploited a variety of marine habitats and resources.