Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The Theory of Island Biogeography

During the last three decades, the impact of chemical pollution has focused almost exclusively on the conventional "priority" pollutants, especially those acutely toxic/carcinogenic pesticides and industrial intermediates displaying persistence in the environment. This spectrum of chemicals, however, is only one piece of the larger puzzle in "holistic" risk assessment. Another diverse group of bioactive chemicals receiving comparatively little attention as potential environmental pollutants includes the pharmaceuticals and active ingredients in personal care products (in this review collectively termed PPCPs), both human and veterinary, including not just prescription drugs and biologics, but also diagnostic agents, "nutraceuticals," fragrances, sun-screen agents, and numerous others. These compounds and their bioactive metabolites can be continually introduced to the aquatic environment as complex mixtures via a number of routes but primarily by both untreated and treated sewage. Aquatic pollution is particularly troublesome because aquatic organisms are captive to continual life-cycle, multigenerational exposure. The possibility for continual but undetectable or unnoticed effects on aquatic organisms is particularly worrisome because effects could accumulate so slowly that major change goes undetected until the cumulative level of these effects finally cascades to irreversible change--change that would otherwise be attributed to natural adaptation or ecologic succession. As opposed to the conventional, persistent priority pollutants, PPCPs need not be persistent if they are continually introduced to surface waters, even at low parts-per-trillion/parts-per-billion concentrations (ng-microg/L). Even though some PPCPs are extremely persistent and introduced to the environment in very high quantities and perhaps have already gained ubiquity worldwide, others could act as if they were persistent, simply because their continual infusion into the aquatic environment serves to sustain perpetual life-cycle exposures for aquatic organisms. This review attempts to synthesize the literature on environmental origin, distribution/occurrence, and effects and to catalyze a more focused discussion in the environmental science community.

Pharmaceuticals and personal care products in the environment: agents of subtle change?

Molecular chaperones, including the heat-shock proteins (Hsps), are a ubiquitous feature of cells in which these proteins cope with stress-induced denaturation of other proteins. Hsps have received the most attention in model organisms undergoing experimental stress in the laboratory, and the function of Hsps at the molecular and cellular level is becoming well understood in this context. A complementary focus is now emerging on the Hsps of both model and nonmodel organisms undergoing stress in nature, on the roles of Hsps in the stress physiology of whole multicellular eukaryotes and the tissues and organs they comprise, and on the ecological and evolutionary correlates of variation in Hsps and the genes that encode them. This focus discloses that (a) expression of Hsps can occur in nature, (b) all species have hsp genes but they vary in the patterns of their expression, (c) Hsp expression can be correlated with resistance to stress, and (d) species' thresholds for Hsp expression are correlated with levels of stress that they naturally undergo. These conclusions are now well established and may require little additional confirmation; many significant questions remain unanswered concerning both the mechanisms of Hsp-mediated stress tolerance at the organismal level and the evolutionary mechanisms that have diversified the hsp genes.

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Heat-shock proteins, molecular chaperones, and the stress response: evolutionary and ecological physiology

The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

An increasing body of evidence suggests that microorganisms are far more sensitive to heavy metal stress than soil animals or plants growing on the same soils. Not surprisingly, most studies of heavy metal toxicity to soil microorganisms have concentrated on effects where loss of microbial function can be observed and yet such studies may mask underlying effects on biodiversity within microbial populations and communities. The types of evidence which are available for determining critical metal concentrations or loadings for microbial processes and populations in agricultural soil are assessed, particularly in relation to the agricultural use of sewage sludge. Much of the confusion in deriving critical toxic concentrations of heavy metals in soils arises from comparison of experimental results based on short-term laboratory ecotoxicological studies with results from monitoring of long-term exposures of microbial populations to heavy metals in field experiments. The laboratory studies in effect measure responses to immediate, acute toxicity (disturbance) whereas the monitoring of field experiments measures responses to long-term chronic toxicity (stress) which accumulates gradually. Laboratory ecotoxicological studies are the most easily conducted and by far the most numerous, but are difficult to extrapolate meaningfully to toxic effects likely to occur in the field. Using evidence primarily derived from long-term field experiments, a hypothesis is formulated to explain how microorganisms may become affected by gradually increasing soil metal concentrations and this is discussed in relation to defining “safe” or “critical” soil metal loadings for soil protection.

Toxicity of heavy metals to microorganisms and microbial processes in agricultural soils: a review.

The acute fish test is an animal test whose ecotoxicological relevance is worthy of discussion. The primary aim of protection in ecotoxicology is the population and not the individual. Furthermore the concentration of pollutants in the environment is normally not in the lethal range. Therefore the acute fish test covers solely the situation after chemical spills. Nevertheless, acute fish toxicity data still belong to the base set used for the assessment of chemicals. The embryo test with the zebrafish Danio rerio (DarT) is recommended as a substitute for the acute fish test. For validation an international laboratory comparison test was carried out. A summary of the results is presented in this paper. Based on the promising results of testing chemicals and waste water the test design was validated by the DIN-working group "7.6 Fischei-Test". A normed test guideline for testing waste water with fish is available. The test duration is short (48 h) and within the test different toxicological endpoints can be examined. Endpoints from the embryo test are suitable for QSAR-studies. Besides the use in ecotoxicology the introduction as a toxicological model was investigated. Disturbance of pigmentation and effects on the frequency of heart-beat were examined. A further important application is testing of teratogenic chemicals. Based on the results DarT could be a screening test within preclinical studies.

DarT: The embryo test with the Zebrafish Danio rerio--a general model in ecotoxicology and toxicology.

Differential gene expression as a toxicant-sensitive endpoint in zebrafish embryos and larvae.

In vertebrate reproductive endocrinology sex steroids play a pivotal role via binding to receptors. However, information on the origin and relevance of sex steroids in invertebrates is limited. This review highlights current literature on steroid receptors in aquatic invertebrates and reports on some new findings. It has been shown that invertebrates of the deuterostome clade, such as Acrania and Echinodermata, respond to estrogens and androgens and, at least in Branchiostoma, an estrogen receptor has been cloned. Within the protostomes, most findings are related to aquatic molluscs. Sex steroid receptor-like proteins are abundant in gastropods, bivalves and cephalopods and also sex hormone signalling shows partial similarity to the deuterostomes. In ecdysozoans, however, the impact of sex steroids is still a matter of debate even though there is evidence on the presence of estrogen receptor-like proteins in Crustacea and on physiological effects of estrogens in both Nematoda and Crustacea. Recent findings suggest the presence of an estrogen receptor α-like protein of unclear physiological role in Gammarus fossarum (Crustacea). Binding studies revealed the crustacean Hyalella azteca to possess specific binding sites only for androgens but not for estrogens suggesting a possible limitation to functional androgen receptors in this species. Further studies have to be conducted to shed more light into the discussion about the controversy about sex steroid receptors in invertebrates.

Sex steroid receptor evolution and signalling in aquatic invertebrates.

Zur Erfassung der UV-Filtersubstanzen wird eine Methode vorgestellt, die die simultane Bestimmung dieser Verbindungen und von Organochlorverbindungen wie PCB und DDT in unterschiedlichen Fischkompartimenten bis in den ng/kg-Bereich ermoglicht. Die Nachweisgrenzen liegen zwischen 40 und 90 ng/kg Filet und die Wiederfindungsraten bewegen sich zwischen 78 und 104%. Die Belastung von Wasser und Fischen des Meerfelder Maares, Eifel, mit UV-Filtersubstanzen wurde 1991 und 1993 exemplarisch untersucht. Insgesamt konnten in den Fischen des Meerfelder Maares 6 UV-Filtersubstanzen identifiziert und quantifiziert werden. Die im Sommer 1991 gefangenen Barsche waren mit 2,0 mg/kg Fett (Summe nachgewiesener UV-Filtersubstanzen) und die Rotaugen von 1993 mit 0,50 mg/kg Fett belastet. In beiden Fischarten lag die Belastung in der gleichen Grosenordnung wie die der Organochlorverbindungen PCB und DDT. In den Rotaugen aus drei weiteren deutschen Seen konnte im Filet Methylbenzylidencampher, eine lipophile UV-Filtersubstanz, nachgewiesen werden. Diese Befunde zeigen, das UV-Filtersubstanzen in deutschen Seen weir verbreitet und vermutlich als relevante Umweltchemikalien zu betrachten sind. Da im Wasser der Seen die Konzentrationen der UV-Filter substanzen meistens unter der Bestimmungsgrenze lagen, konnen Fische fur diese lipophilen Verbindungen als Expositionsmonitor verwendet werden. Eine okotoxikologische Bewertung ist zum jetzigen Zeitpunkt nicht moglich, da die Datenlage vollig unzureichend ist.

UV-Filtersubstanzen in Wasser und Fischen

To investigate the use of stress proteins hsp60 and hsp70 as sublethal biomarkers for contaminant exposure in sediments, two infaunal (Ampelisca abdita, estuarine; Rhepoxynius abronius, marine) and one epifaunal (Hyalella azteca, freshwater) amphipod species were exposed for 24 h to solutions of the heavy metal cadmium, the pesticides diazinon and dieldrin, and the polycyclic aromatic hydrocarbon fluoranthene. All three species are routinely used in standard sediment toxicity tests. Analysis of hsp60 and hsp70 was performed using western blotting techniques with subsequent comparative quantification by densitometry. Results demonstrated compound and species-specific induction of stress protein synthesis. Whereas one member of the hsp70 protein family showed the most sensitive response to xenobiotic compounds in H. azteca, several members of the hsp60 protein family were the main proteins induced in A. abdita and R. abronius. Sensitivity of the detected stress protein response was highest in H. azteca with significant effects at concentrations 110-, 50-, >1,000-, and >1-fold lower than LC50 values for cadmium, diazinon, dieldrin, and fluoranthene, respectively. The corresponding values were >5 (cadmium), 0.7 (diazinon), >1 (dieldrin), and 2.9 (fluoranthene) for A. abdita, and >2 (cadmium), 3.1 (diazinon), > 100 (dieldrin), and >2.9 (fluoranthene) for R. abronius.

Roland Nagel

Papers

DarT: The embryo test with the Zebrafish Danio rerio--a general model in ecotoxicology and toxicology.

Differential gene expression as a toxicant-sensitive endpoint in zebrafish embryos and larvae.

Sex steroid receptor evolution and signalling in aquatic invertebrates.

UV-Filtersubstanzen in Wasser und Fischen

Stress proteins hsp60 and hsp70 in three species of amphipods exposed to cadmium, diazinon, dieldrin and fluoranthene