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The appearance of high biomass algal blooms including harmful ones is frequently both sudden and unanticipated, and their duration is normally brief. These characteristics have historically frustrated detailed observation as well as theoretical understanding. Monitoring programmes are now relieving the first problem, but modeling and prediction still present major challenges. Predictions are of course blurred by historical contingency, but several other brakes probably also contribute to slow progress. These include i) a general focus on vegetative growth to the exclusion of other life history stages, ii) a view that division rates and other traits are fixed parameters, while phenological adaptations are of no consequence, and iii) over simplification of trophic links and other forms of biological interactions that affect population dynamics

Of all climatic zones on earth, Arctic areas have experienced the greatest climate change in recent decades. Predicted changes, including a continuing rise in temperature and precipitation and a reduction in snow cover, are expected to have a large impact on Arctic life. Large numbers of birds breed on the Arctic tundra, and many of these, such as shorebirds and passerines, feed on arthropods. Their chicks depend on a short insect population outburst characteristic of Arctic areas. To predict the consequences of climate change for reproduction in these birds, insight into arthropod phenology is essential. We investigated weather-related and seasonal patterns in abundance of surface-active arthropods during four years in the tundra of NW Taimyr, Siberia. The resulting statistical models were used to hindcast arthropod abundance on the basis of a 33-year weather dataset collected in the same area. Daily insect abundance was correlated closely with date, temperature, and, in some years, with wind and precipitation. An additional correlation with the number of degree-days accumulated after 1 June suggests that the pool of potential arthropod recruits is depleted in the course of the summer. The amplitude of short-term, weather-induced variation was as large as that of the seasonal variation. The hindcasted dates of peak arthropod abundance advanced during the study period, occurring seven days earlier in 2003 than in 1973. The timing of the period during which birds have a reasonable probability of finding enough food to grow has changed as well, with the highest probabilities now occurring at earlier dates. At the same time, the overall length of the period with probabilities of finding enough food has remained unchanged. The result is an advancement of the optimal breeding date for breeding birds. To take advantage of the new optimal breeding time, Arctic shorebirds and passerines must advance the start of breeding, and this change could affect the entire migratory sc

In all marine benthic environments, organism replacement depends on recruitment limitation, i.e. the impact of both pre- and post-settlement events on the success of recruitment. The relative contribution of pre- versus post-settlement processes in shaping adult populations has been extensively studied. Most analyses concluded that recruitment limitation is a strong determinant of adults' density. The magnitude of its limitation depends on context, varies with species, and can be strongly modified by all the events preceding and following recruitment itself. A comparison of the outcome of recruitment limitation on hard- and soft-bottom communities has often been neglected. The rules governing these two environments, in both the inter- and the subtidal, might be inferred only by comparing and possibly integrating soft- and hard-bottom ecologies. The highly variable situation that larvae face in the water column is followed by the variability linked to local features, influencing, in its turn, larval settlement and juvenile survival (post-settlement period). A better knowledge of these processes will be possible only by focusing on their relative importance in the two environments and with research on the brief but significant time of larval settlement. (C) 2002 Ifremer/CNRS/IRD/Editions scientiliques et medicales Elsevier SAS. All rights reserved., Le remplacement des organismes dans l’environnement benthique dépend de la limitation du recrutement, succession des événements précédant ou suivant immédiatement la sédimentation larvaire. La contribution relative des processus de pré- et de post-installation dans la structuration des populations adultes a été largement étudiée. La majeure partie des analyses conclut que le recrutement est un facteur clé pour assurer le renouvellement et le maintien des adultes. Une comparaison de la limitation du recrutement sur les communautés de substrats durs et meubles a été rarement effectuée. Les processus affectant ces deux environnements, aussi bien dans la zone intertidale que subtidale, peuvent être déduites seulement en comparant (et éventuellement en intégrant) l’écologie des fonds durs et meubles. La situation très variable que les larves rencontrent dans la colonne d’eau (période de pré-installation) est dûe à la variabilité des caractéristiques locales. Celles-ci influencent, à leur tour, l’installation des larves et la survie des juvéniles (période de post-installation). Une meilleure connaissance de ces processus sera possible seulement après l’identification de leur importance relative dans les deux environnements et si l’étude de la période d’installation des larves, brève mais significatif, sont étudiés.

In all marine benthic environments, organism replacement depends on recruitment limitation, i.e. the impact of both pre- and post-settlement events on the success of recruitment. The relative contribution of pre- versus post-settlement processes in shaping adult populations has been extensively studied. Most analyses concluded that recruitment limitation is a strong determinant of adults' density. The magnitude of its limitation depends on context, varies with species, and can be strongly modified by all the events preceding and following recruitment itself. A comparison of the outcome of recruitment limitation on hard- and soft-bottom communities has often been neglected. The rules governing these two environments, in both the inter- and the subtidal, might be inferred only by comparing and possibly integrating soft- and hard-bottom ecologies. The highly variable situation that larvae face in the water column is followed by the variability linked to local features, influencing, in its turn, larval settlement and juvenile survival (post-settlement period). A better knowledge of these processes will be possible only by focusing on their relative importance in the two environments and with research on the brief but significant time of larval settlement. (C) 2002 Ifremer/CNRS/IRD/Editions scientiliques et medicales Elsevier SAS. All rights reserved., Le remplacement des organismes dans l’environnement benthique dépend de la limitation du recrutement, succession des événements précédant ou suivant immédiatement la sédimentation larvaire. La contribution relative des processus de pré- et de post-installation dans la structuration des populations adultes a été largement étudiée. La majeure partie des analyses conclut que le recrutement est un facteur clé pour assurer le renouvellement et le maintien des adultes. Une comparaison de la limitation du recrutement sur les communautés de substrats durs et meubles a été rarement effectuée. Les processus affectant ces deux environnements, aussi bien dans la zone intertidale que subtidale, peuvent être déduites seulement en comparant (et éventuellement en intégrant) l’écologie des fonds durs et meubles. La situation très variable que les larves rencontrent dans la colonne d’eau (période de pré-installation) est dûe à la variabilité des caractéristiques locales. Celles-ci influencent, à leur tour, l’installation des larves et la survie des juvéniles (période de post-installation). Une meilleure connaissance de ces processus sera possible seulement après l’identification de leur importance relative dans les deux environnements et si l’étude de la période d’installation des larves, brève mais significatif, sont étudiés.

In all marine benthic environments, organism replacement depends on recruitment limitation, i.e. the impact of both pre- and post-settlement events on the success of recruitment. The relative contribution of pre- versus post-settlement processes in shaping adult populations has been extensively studied. Most analyses concluded that recruitment limitation is a strong determinant of adults' density. The magnitude of its limitation depends on context, varies with species, and can be strongly modified by all the events preceding and following recruitment itself. A comparison of the outcome of recruitment limitation on hard- and soft-bottom communities has often been neglected. The rules governing these two environments, in both the inter- and the subtidal, might be inferred only by comparing and possibly integrating soft- and hard-bottom ecologies. The highly variable situation that larvae face in the water column is followed by the variability linked to local features, influencing, in its turn, larval settlement and juvenile survival (post-settlement period). A better knowledge of these processes will be possible only by focusing on their relative importance in the two environments and with research on the brief but significant time of larval settlement. (C) 2002 Ifremer/CNRS/IRD/Editions scientiliques et medicales Elsevier SAS. All rights reserved., Le remplacement des organismes dans l’environnement benthique dépend de la limitation du recrutement, succession des événements précédant ou suivant immédiatement la sédimentation larvaire. La contribution relative des processus de pré- et de post-installation dans la structuration des populations adultes a été largement étudiée. La majeure partie des analyses conclut que le recrutement est un facteur clé pour assurer le renouvellement et le maintien des adultes. Une comparaison de la limitation du recrutement sur les communautés de substrats durs et meubles a été rarement effectuée. Les processus affectant ces deux environnements, aussi bien dans la zone intertidale que subtidale, peuvent être déduites seulement en comparant (et éventuellement en intégrant) l’écologie des fonds durs et meubles. La situation très variable que les larves rencontrent dans la colonne d’eau (période de pré-installation) est dûe à la variabilité des caractéristiques locales. Celles-ci influencent, à leur tour, l’installation des larves et la survie des juvéniles (période de post-installation). Une meilleure connaissance de ces processus sera possible seulement après l’identification de leur importance relative dans les deux environnements et si l’étude de la période d’installation des larves, brève mais significatif, sont étudiés.