We conducted field surveys of rocky intertidal communities at 18 sites distributed between 29°S and 36°S on the coast of central Chile in order to document broad patterns of functional and trophic group abundance and evaluate their association with oceanographic features. Results showed that the main sessile components of the landscape throughout the region were kelps (16%) and crustose algae (48%) in the low intertidal zone, while mussels beds (30%) and corticated algae (32%) dominated the mid-intertidal zone. Geographic trends in abundance across the entire region varied from no clear regional patterns for some groups (e.g. barnacles), to smooth gradients increasing or decreasing toward higher latitudes for others (kelps and ephemeral algae) and to an abrupt switch from dominant to scarce northward of 32°S in 1 group (mussels). Significant among-site negative correlations were detected between the abundances of most algal functional groups and between mussels and barnacles. Herbivore density was negatively correlated with kelp and corticated algal cover, and positively correlated with crustose algal abundance. These correlations reinforce the notion that local biological interactions can partially account for the among-site variability in functional group abundance. We assessed the influence of mesoscale oceanographic features through satellite image analyses, by classifying the study sites as either strongly or weakly influenced by coastal upwelling. At sites strongly influenced by upwelling, we found significantly higher cover of kelps in the low intertidal zone and of corticated algae in the mid-intertidal zone. Cover of ephemeral algae in the mid-intertidal zone was significantly lower at sites strongly affected by upwelling. Contrary to predictions of bottom-up community regulation models, we found no significant differences in abundance of sessile filter feeders (mussels or barnacles), herbivores or carnivores. A significant proportion of the regional variation in abundance in some of the most abundant functional groups within each tidal level was associated with the latitudinal gradient in annual mean sea surface temperature (SST). We detected a significant correlation between SST and the abundance of kelps and crustose algae in the low intertidal zone, and mussels and ephemeral algae in the mid-intertidal zone. The abrupt change in the abundance of mussels in the mid-intertidal zone at about 32°S may indicate a similarly abrupt change in biological or environmental conditions. Lack of significant correlation between the abundance of mussels and other functional groups suggests that biological interactions may not be responsible for this geographic discontinuity. We suggest that oceanography may be largely involved in the geographic variability detected in patterns of community structure. Recent remote sensing studies documenting oceanographic discontinuities around the 32°S zone support our suggestion. Our results highlight the need for further experimental and oceanographic studies in areas ...

The number of species coexisting in ecological communities must be a consequence of processes operating on both local and regional scales. Although a great deal of experimental work has been devoted to local causes of diversity, little is known about the effects of regional processes on local diversity and how they contribute to global diversity patterns in marine systems. We tested the effects of latitude and the richness of the regional species pool on the species richness of local epifaunal invertebrate communities by sampling the diversity of local sites in 12 independent biogeographic regions from 62°S to 63°N latitude. Both regional and local species richness displayed significant unimodal patterns with latitude, peaking at low latitudes and decreasing toward high latitudes. The latitudinal diversity gradient was represented at the scale of local sites because local species richness was positively and linearly related to regional species richness. The richness of the regional species pool explained 73-76% of local species richness. On a global scale, the extent of regional influence on local species richness was nonrandom-the proportion of regional biota represented in local epifaunal communities increased significantly from low to high latitudes. The strong effect of the regional species pool implies that patterns of local diversity in temperate, tropical, and high-latitude marine benthic communities are influenced by processes operating on larger spatiotemporal scales than previously thought. U nderstanding the forces that shape spatiotemporal variation in species diversity remains one of the major issues confronting ecologists (1). Experiments conducted at local sites (spatial scale of meters to hundreds of meters) demonstrate that biological interactions, productivity, habitat complexity, disturbance, and environmental stress interact to produce variability in local species richness (i.e., number of species) (2, 3). But, local diversity must also be affected by regional-scale processes [spatial scale of 200 to thousands of kilometers (4)] because local communities are integral components of larger biogeographic regions. Tests of the importance of regional-scale phenomena typically involve quantifying the relationship between regional and local species richness.On a global scale, species diversity typically declines with increasing latitude toward the poles, especially on land (5, 6). The linear or modal function describing the relationship between diversity and latitude varies by taxa and sampling resolution, but an emerging generalization from empirical (6) and meta-analyses of latitudinal diversity patterns (7) is that the latitudinal pattern is chiefly based on the decline of regional (gamma) diversity toward the poles and is not due to variation in local (alpha) community richness. In the ocean, however, there are few studies of local diversity across broad latitudinal gradients (7,8). Because of the remote (e.g., ship-based) methods commonly used to sample the diversity of soft-bottom benthic comm...

Stakeholders increasingly expect ecosystem assessments as part of advice on fisheries management. Quantitative models to support fisheries decision‐making may be either strategic (‘big picture’, direction‐setting and contextual) or tactical (focused on management actions on short timescales), with some strategic models informing the development of tactical models. We describe and review ‘Models of Intermediate Complexity for Ecosystem assessments’ (MICE) that have a tactical focus, including use as ecosystem assessment tools. MICE are context‐ and question‐driven and limit complexity by restricting the focus to those components of the ecosystem needed to address the main effects of the management question under consideration. Stakeholder participation and dialogue is an integral part of this process. MICE estimate parameters through fitting to data, use statistical diagnostic tools to evaluate model performance and account for a broad range of uncertainties. These models therefore address many of the impediments to greater use of ecosystem models in strategic and particularly tactical decision‐making for marine resource management and conservation. MICE are capable of producing outputs that could be used for tactical decision‐making, but our summary of existing models suggests this has not occurred in any meaningful way to date. We use a model of the pelagic ecosystem in the Coral Sea and a linked catchment and ocean model of the Gulf of Carpentaria, Australia, to illustrate how MICE can be constructed. We summarize the major advantages of the approach, indicate opportunities for the development of further applications and identify the major challenges to broad adoption of the approach.