Depletion, Degradation, and Recovery Potential of Estuaries and Coastal Seas (original) (raw)
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1. The Chilean rocky coast has been exploited for food by coastal gatherers for at least 8500 years BP and probably was an important factor in how prehistoric people were able to colonize the South Americas Pacific Rim. The main species targeted in the past were the same as those today except that now the gatherers are resident and the fishing activity is more intense and persistent.
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Science, 2001
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.
Proceedings of the Royal Society B: Biological Sciences, 2012
Historic baselines are important in developing our understanding of ecosystems in the face of rapid global change. While a number of studies have sought to determine changes in extent of exploited habitats over historic timescales, few have quantified such changes prior to late twentieth century baselines. Here, we present, to our knowledge, the first ever large-scale quantitative assessment of the extent and biomass of marine habitat-forming species over a 100-year time frame. We examined records of wild native oyster abundance in the United States from a historic, yet already exploited, baseline between 1878 and 1935 (predominantly 1885 -1915), and a current baseline between 1968 and 2010 (predominantly 2000 -2010). We quantified the extent of oyster grounds in 39 estuaries historically and 51 estuaries from recent times. Data from 24 estuaries allowed comparison of historic to present extent and biomass. We found evidence for a 64 per cent decline in the spatial extent of oyster habitat and an 88 per cent decline in oyster biomass over time. The difference between these two numbers illustrates that current areal extent measures may be masking significant loss of habitat through degradation.
MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser
Marine Ecology Progress Series, 2008
Large-scale research on the environmental, biological, and anthropogenic drivers of fish distributions, abundances, and community structure can identify patterns and trends within systems, provide mechanistic insight into ecosystem functioning, and contribute to ecosystembased fisheries management. This study synthesized 10 yr of extensive fisheries-independent bottom trawl data (2002 to 2011) to evaluate drivers of demersal fish community structure in Chesapeake Bay, the largest estuary in the United States. Changes in community composition were assessed using constrained correspondence analysis. Also, aggregate community metrics (species richness, Simpson diversity, and catch-per-unit-effort [CPUE] of species groups) were modeled using generalized additive models. Five species (Atlantic croaker, white perch, spot, striped bass, and summer flounder) accounted for > 75% of the total trawled biomass. The demersal fish community was primarily structured by the latitudinal salinity gradient that largely differentiated anadromous fishes from coastal shelf spawning species and elasmobranchs, with low overall CPUE and richness in mesohaline waters. Low dissolved oxygen concentrations (below ~4 mg l −1 ) greatly suppressed CPUE and diversity metrics and appeared to displace fish biomass toward the northern and southern edges of the bay's mainstem channel. Water temperature and month strongly influenced the seasonal dynamics of community composition and metrics. Community composition and biomass shifted after 2007, with a substantial decline in annual CPUE of some species groups. Recruitment and fishing indices for the dominant species were the best predictors of the interannual patterns in community metrics, outperforming various other climatic and biological annual-scale covariates.
Historical Impacts on River Fauna, Shifting Baselines, and Challenges for Restoration
BioScience, 2009
A ll human populations modify the landscapes and ecosystems they inhabit, whether by direct exploitation of natural resources or through activities such as damming rivers or introducing alien species (Reynolds et al. 2001, Olden et al. 2008). Although less technologically advanced societies can affect their environments profoundly over time (Pinnegar and Engelhard 2008), especially when colonizing islands, it is typically postindustrial societies that have made the biggest impact on the natural environments of continents (e.g., Crosby 2000). The process of large-scale, dramatic, anthropogenic environmental change had been occurring in western Europe since medieval times, but the major emigration of Europeans during the 17th and 18th centuries to parts of the world that had hitherto been influenced only by indigenous peoples with relatively low population sizes produced rapid and dramatic environmental changes (Crosby 2000). Those colonizers who formed coastal communities looked to the sea for subsistence and, later, for wealth. The environmental cost was huge. Indeed, historical overharvesting of marine animals, including fishes, whales, and oysters, has been implicated in the collapse of coastal ecosystems (Jackson et al. 2001, Saenz-Arroyo et al. 2006). In each case, a species or stock, such as Atlantic cod or Chesapeake Bay oysters, was harvested to the point of ecological extinction, and the wide-ranging effects of their decimation on food webs are still evident today. Overharvesting, it has been argued, was typically the first environmental disturbance in coastal and estuarine ecosystems colonized by postindustrial societies, occurring before severe habitat alteration, pollution, or introduction of alien species (Jackson et al. 2001). But many coastal communities also looked to freshwaters to supplement food from the sea (Vickers 2004), and settlement was by no means limited to coastal regions. European colonists in North America and Australia, in particular, made their way inland relatively early in the colonization process, usually settling near lakes or along rivers (Crosby 2000). Exploitation of freshwater animals began right away: People took advantage of abundant aquatic wildlife, typically moving through a series of steps from subsistence, artisanal, and semicommercial fishing to, finally, fully commercial fisheries (see, e.g., Trautman 1981, Vickers 2004). The largest fish species were targeted most intensely (see, e.g., Rowland 1989, Meengs and Lackey 2005), but other animals became commercially important soon after (Naiman et al. 1988, Anthony and Downing 2001). In virtually every case, overharvesting rapidly devastated stocks of the most economically valuable species.