Abundance of harbor porpoise (Phocoena phocoena) in three Alaskan regions, corrected for observer errors due to perception bias and species misidentification, and corrected for animals submerged from view

Estimating the abundance of cetaceans from aerial survey data requires careful attention to survey design and analysis. Once an aerial observer perceives a marine mammal or group of marine mammals, he or she has only a few seconds to identify and enumerate the individuals sighted, as well as to determine the distance to the sighting and record this information. In line-transect survey analyses, it is assumed that the observer has correctly identified and enumerated the group or individual. We describe methods used to test this assumption and how survey data should be adjusted to account for observer errors. Harbor porpoises (Phocoena phocoena) were censused during aerial surveys in the summer of 1997 in Southeast Alaska (9844 km survey effort), in the summer of 1998 in the Gulf of Alaska (10,127 km), and in the summer of 1999 in the Bering Sea (7849 km). Sightings of harbor porpoise during a beluga whale (Phocoena phocoena) survey in 1998 (1355 km) provided data on harbor porpoise abundance in Cook Inlet for the Gulf of Alaska stock. Sightings by primary observers at side windows were compared to an independent observer at a belly window to estimate the probability of misidentification, underestimation of group size, and the probability that porpoise on the surface at the trackline were missed (perception bias, g(0)). There were 129, 96, and 201 sightings of harbor porpoises in the three stock areas, respectively. Both g(0) and effective strip width (the realized width of the survey track) depended on survey year, and g(0) also depended on the visibility reported by observers. Harbor porpoise abundance in 1997–99 was estimated at 11,146 animals for the Southeast Alaska stock, 31,046 animals for the Gulf of Alaska stock, and 48,515 animals for the Bering Sea stock.

Decline in sea otter (Enhydra lutris) populations along the Alaska Peninsula, 1986–2001

During the 1990s, sea otter (Enhydra lutris) counts in the Aleutian archipelago decreased by 70% throughout the archipelago between 1992 and 2000. Recent aerial surveys in the Aleutians did not identify the eastward extent of the decline; therefore we conducted an aerial survey along the Alaska Peninsula for comparison with baseline information. Since 1986, abundance estimates in offshore habitat have declined by 27– 49% and 93 –94% in northern and southern Alaska Peninsula study areas, respectively. During this same time period, sea otter density has declined by 63% along the island coastlines within the south Alaska Peninsula study area. Between 1989 and 2001, sea otter density along the southern coastline of the Alaska Peninsula declined by 35% to the west of Castle Cape but density increased by 4% to the east, which may indicate an eastward extent of the decline. In all study areas, sea otters were primarily concentrated in bays and lagoon, whereas historically, large rafts of otters had been distributed offshore. The population declines observed along the Alaska Peninsula occurred at roughly the same time as declines in the Aleutian islands to the east and the Kodiak archipelago to the west. Since the mid-1980s, the sea otter population throughout southwest Alaska has declined overall by an estimated 56–68%, and the decline may be one of the most significant sea otter conservation issues in our time.

Mapping the shallow-water coral ecosystems of the Freely Associated States: an implementation plan

This Freely Associated States Shallow-water Coral Ecosystem Mapping Implementation Plan (FAS MIP) presents a framework for the development of shallow-water (~0–40 m; 0–22 fm) benthic habitat and possibly bathymetric maps of critical areas of the Freely Associated States (FAS). The FAS is made up of three self-governing groups of islands and atolls—the Republic of Palau (Palau), the Federated States of Micronesia (FSM), and the Republic of the Marshall Islands (RMI)—that are affiliated with the United States through Compacts of Free Association. This MIP was developed with extensive input from colleges, national and state regulatory and management agencies, federal agencies, non-governmental organizations, and individuals involved in or supporting the conservation and management of the FAS’s coral ecosystems. A list of organizations and individuals that provided input to the development of this MIP is provided in Appendix 1. This MIP has been developed to complement the Coral Reef Mapping Implementation Plan (2nd Draft) released in 1999 by the U.S. Coral Reef Task Force’s Mapping and Information Synthesis Working Group. That plan focused on mapping United States and FAS shallow-water (then defined as <30 m) coral reefs by 2009, based on available funding and geographic priorities, using primarily visual interpretation of aerial photography and satellite imagery. This MIP focuses on mapping the shallow-water (now defined as 0–40 m, rather than 0–30 m) coral ecosystems of the FAS using a suite of technologies and map development procedures. Both this FAS MIP and the 1999 Coral Reef Mapping Implementation Plan (2nd Draft) support to goals of the National Action Plan to Conserve Coral Reefs (U.S. Coral Reef Task Force, 2000). This FAS MIP presents a framework for mapping the coral ecosystems of the FAS and should be considered an evolving document. As priorities change, funding opportunities arise, new data are collected, and new technologies become available, the information presented herein will change.

Literature review for a resource characterization of Cape Romain National Wildlife Refuge

Through research aimed at understanding the coastal environment, surveys designed to help manage the resource, and national programs to monitor environmental condition, we see a picture of a dynamic ecosystem that is Cape Romain National Wildlife Refuge (CRNWR). Currently, there are efforts underway to protect threatened species; monitor fish populations; and quantify the biological, physical, and chemical characteristics of this environment. The potential impacts to this system are just now being understood as ecological responses to human modification are observed and explained. As a starting point, this document compiles existing information about Cape Romain NWR in five topic areas and addresses the potential impacts to the Refuge. This review is intended to serve as a stepping stone to developing a research agenda in support of management of the Refuge. There are various sources of information on which to build a framework for monitoring conditions and detecting change to this environment. For instance, information on basic ecological function in estuarine environments has evolved over several decades. Long-term surveys of Southeast fisheries exist, as well as shellfish and sediment contaminants data from estuaries. Environmental monitoring and biological surveys at the Refuge continue. Recently, studies that examine the impacts to similar coastal habitats have been undertaken. This document puts past studies and ongoing work in context for Refuge managers and researchers. This report recommends that the next phase of this resource characterization focus on: • compiling relevant tabular and spatial data, as identified here, into a Geographic Information System (GIS) framework • assessing the abundance and diversity of fisheries utilizing CRNWR • delineating additional data layers, such as intertidal habitats and subtidal clam beds, from low-level aerial photography, hard copy maps, and other sources • continued inventories of plant and animal species dependent on the Refuge • monitoring physical and chemical environmental parameters using the methodology employed at National Estuarine Research Reserve System (NERRS) and other coastal sites, where appropriate • further definition of the potential risks to the Refuge and preparing responses to likely impacts.

Characteristics and flux of settling particulate matter in neritic waters: The southern Yellow Sea and the East China Sea

The typology and flux of settling particulate matter (SPM) were investigated based on sediment trap sampling at six typical stations in the Yellow Sea and the East China Sea. The settling particulate matter in the neritic seas was sorted into three categories, lithogenic particles, living organisms, and particle aggregates. The mass of individual organisms is an important portion of particulate matter in the neritic waters. The aggregates contain six types, mucus aggregates, fecal pellets, diatom aggregates, silicoflagellate aggregates, tintinnids, and miscellaneous aggregates, of which the silicoflagellate aggregates and tintinnids are the most abundant in the Yellow Sea and the East China Sea. High particle fluxes, such as 215 to 874 g m(-2). day(-1) SPM in the bottom layer, were found at three stations where the water was well mixed, and the maximum flux was detected in the boundary area between the Yellow Sea and the East China Sea, where a wide nepheloid layer was present. Hence, particle flux in neritic waters can be easily shifted by water turbulence. The net vertical flux (123 to 961 mg C day(-1)), the contribution of lateral advection to resuspension flux (5 to 76%), and the particulate organic carbon export ratio (18 to 60%) were estimated for the other three stations where the water was stratified. The highest values were all found in the upwelling area off the Zhejiang coast, suggesting that the area of high productivity provides a high net vertical flux of SPM. (C) 2010 Elsevier Ltd. All rights reserved.

Seasonal changes in the distribution of dissolved organic nitrogen in coastal and open-ocean waters in the North East Pacific: sources and sinks

The distribution of dissolved organic nitrogen (DON) and nitrate were determined seasonally (winter, spring and summer) during three years along line P, i.e. an E-W transect from the coast of British Columbia, Canada, to Station P (50degreesN, 145degreesW) in the subarctic North East Pacific Ocean. In conjunction, DON measurements were made in the Straits of Juan de Fuca and Georgia within an estuarine system connected to the NE Pacific Ocean. The distribution of DON at the surface showed higher values of 4-17 muM in the Straits relative to values of 4-10 muM encountered along line P, respectively. Along line P, the concentration of DON showed an inshore-offshore gradient at the surface with higher values near the coast. The equation for the conservation of DON showed that horizontal transport of DON (inshore-offshore) was much larger than vertical physical mixing. Horizontal advection of DON-rich waters from the coastal estuarine system to the NE Pacific Ocean was likely the cause of the inshore-offshore gradient in the concentration of DON. Although the concentration of DON was very variable in space and time, it increased from winter to summer, with an average build up of 4.3 muM in the Straits and 0.7 muM in the NE subarctic Pacific. This implied seasonal DON sources of 0.3 mmol N m(-2) d(-1) at Station P and 1.5 mmol N m(-2) d(-1) in the Straits, respectively. These seasonal DON accumulation rates corresponded to about 15-20% of the seasonal nitrate uptake and suggested that there was a small seasonal build up of labile DON at the surface. However, the long residence times of 180-1560 d indicated that the most of the DON pool in surface waters was refractory in two very different productivity regimes of the NE Pacific. (C) 2002 Elsevier Science Ltd. All rights reserved.

Spatial variability in biomass and production of heterotrophic bacteria in the East China Sea and the Yellow Sea

The distributions of heterotrophic bacterial abundance and production were investigated in the East China Sea and the Yellow Sea during the autumn of 2000 and spring of 2001. Bacterial abundance varied in the range 3.2-15.7 (averaging 5.7) x 10(5) and 2.3-13.6 (averaging 6.2) x 10(5) cells cm(-3) in the spring and autumn, respectively. During autumn, bacterial production (BP) (0.27-7.77 mg C m(-3) day(-1)) was on average 3 fold that in spring (0.001-2.04 mg C m(-3) day(-1)). Bacterial average turnover rate (ratio of bacterial production:bacterial biomass, mu=0.21 day(-1)) in autumn was 3 times as high as in spring (0.07 day(-1)). The ratio of integrated bacterial biomass to integrated phytoplankton biomass in the euphotic zone ranged from 4 to 101% (averaging 35%) in spring and 24 to 556% (averaging 121%) in autumn. The results indicate that the distributions of heterotrophic bacteria were controlled generally by temperature in spring and additionally by substrate supply in autumn. (C) 2010 Elsevier Ltd. All rights reserved.

Use of Continuous Plankton Recorder information in support of marine management: applications in fisheries, environmental protection, and in the study of ecosystem response to environmental change

The Continuous Plankton Recorder (CPR) survey was conceived from the outset as a programme of applied research designed to assist the fishing industry. Its survival and continuing vigour after 70 years is a testament to its utility, which has been achieved in spite of great changes in our understanding of the marine environment and in our concerns over how to manage it. The CPR has been superseded in several respects by other technologies, such as acoustics and remote sensing, but it continues to provide unrivalled seasonal and geographic information about a wide range of zooplankton and phytoplankton taxa. The value of this coverage increases with time and provides the basis for placing recent observations into the context of long-term, large-scale variability and thus suggesting what the causes are likely to be. Information from the CPR is used extensively in judging environmental impacts and producing quality status reports (QSR); it has shown the distributions of fish stocks, which had not previously been exploited; it has pointed to the extent of ungrazed phytoplankton production in the North Atlantic, which was a vital element in establishing the importance of carbon sequestration by phytoplankton. The CPR continues to be the principal source of large-scale, long-term information about the plankton ecosystem of the North Atlantic. It has recently provided extensive information about the biodiversity of the plankton and about the distribution of introduced species. It serves as a valuable example for the design of future monitoring of the marine environment and it has been essential to the design and implementation of most North Atlantic plankton research.

An overview of Calanus helgolandicus ecology in European waters

We review current knowledge and understanding of the biology and ecology of the calanoid copepod Calanus helgolandicus in European waters, as well as provide a collaborative synthesis of data from 18 laboratories and 26 sampling stations in areas distributed from the northern North Sea to the Aegean and Levantine Seas. This network of zooplankton time-series stations has enabled us to collect and synthesise seasonal and multi-annual data on abundance, body size, fecundity, hatching success and vertical distribution of C. helgolandicus. An aim was to enable comparison with its congener Calanus finmarchicus, which has been studied intensively as a key component of European and north east Atlantic marine ecosystems. C. finmarchicus is known to over-winter at depth, whereas the life-cycle of C. helgolandicus is less well understood. Overwintering populations of C. helgolandicus have been observed off the Atlantic coast between 400 and 800 m, while in the Mediterranean there is evidence of significant deep-water populations at depths as great as 4200 m. The biogeographical distribution of C. helgolandicus in European coastal waters covers a wide range of habitats, from open ocean to coastal environments, and its contribution to mesozooplankton biomass ranges from 6% to 93%. Highest abundances were recorded in the Adriatic and off the west coast of Spain. C. helgolandicus is generally found in 9-20 C water, with maximum abundances from 13-17 C. In contrast, C. finmarchicus is found in cooler water between 0 and 15 C, with peak abundances from 0 to 9 C. As water has warmed in the North Atlantic over recent decades, the range of C. helgolandicus and its abundance on the fringes of its expanding range have increased. This review will facilitate development of population models of C. helgolandicus. This will not only help answer remaining questions but will improve our ability to forecast future changes, in response to a warming climate, in the abundance and distribution of this important species.

Relating sardine recruitment in the Northern Benguela to satellite-derived sea surface height using a neural network pattern recognition approach

Processes of enrichment, concentration and retention are thought to be important for the successful recruitment of small pelagic fish in upwelling areas, but are difficult to measure. In this study, a novel approach is used to examine the role of spatio-temporal oceanographic variability on recruitment success of the Northern Benguela sardine Sardinops sagax. This approach applies a neural network pattern recognition technique, called a self-organising map (SOM), to a seven-year time series of satellite-derived sea level data. The Northern Benguela is characterised by quasi-perennial upwelling of cold, nutrient-rich water and is influenced by intrusions of warm, nutrient-poor Angola Current water from the north. In this paper, these processes are categorised in terms of their influence on recruitment success through the key ocean triad mechanisms of enrichment, concentration and retention. Moderate upwelling is seen as favourable for recruitment, whereas strong upwelling, weak upwelling and Angola Current intrusion appear detrimental to recruitment success. The SOM was used to identify characteristic patterns from sea level difference data and these were interpreted with the aid of sea surface temperature data. We found that the major oceanographic processes of upwelling and Angola Current intrusion dominated these patterns, allowing them to be partitioned into those representing recruitment favourable conditions and those representing adverse conditions for recruitment. A marginally significant relationship was found between the index of sardine recruitment and the frequency of recruitment favourable conditions (r super(2) = 0.61, p = 0.068, n = 6). Because larvae are vulnerable to environmental influences for a period of at least 50 days after spawning, the SOM was then used to identify windows of persistent favourable conditions lasting longer than 50 days, termed recruitment favourable periods (RFPs). The occurrence of RFPs was compared with back-calculated spawning dates for each cohort. Finally, a comparison of RFPs with the time of spawning and the index of recruitment showed that in years where there were 50 or more days of favourable conditions following spawning, good recruitment followed (Mann-Whitney U-test: p = 0.064, n = 6). These results show the value of the SOM technique for describing spatio-temporal variability in oceanographic processes. Variability in these processes appears to be an important factor influencing recruitment in the Northern Benguela sardine, although the available data time series is currently too short to be conclusive. Nonetheless, the analysis of satellite data, using a neural network pattern-recognition approach, provides a useful framework for investigating fisheries recruitment problems.

The CPR Survey (1948-1997): a gridded database browser of plankton abundance in the North Sea.

The Continuous Plankton Recorder (CPR) survey provides a unique multi- decadal dataset on the abundance of plankton in the North Sea and North Atlantic and is one of only a few monitoring programmes operating at a large spatio- temporal scale. The results of all samples analysed from the survey since 1946 are stored on an Access Database at the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) in Plymouth. The database is large, containing more than two million records (~80 million data points, if zero results are added) for more than 450 taxonomic entities. An open data policy is operated by SAHFOS. However, the data are not on-line and so access by scientists and others wishing to use the results is not interactive. Requests for data are dealt with by the Database Manager. To facilitate access to the data from the North Sea, which is an area of high research interest, a selected set of data for key phytoplankton and zooplankton species has been processed in a form that makes them readily available on CD for research and other applications. A set of MATLAB tools has been developed to provide an interpolated spatio-temporal description of plankton sampled by the CPR in the North Sea, as well as easy and fast access to users in the form of a browser. Using geostatistical techniques, plankton abundance values have been interpolated on a regular grid covering the North Sea. The grid is established on centres of 1 degree longitude x 0.5 degree latitude (~32 x 30 nautical miles). Based on a monthly temporal resolution over a fifty-year period (1948-1997), 600 distribution maps have been produced for 54 zooplankton species, and 480 distribution maps for 57 phytoplankton species over the shorter period 1958-1997. The gridded database has been developed in a user-friendly form and incorporates, as a package on a CD, a set of options for visualisation and interpretation, including the facility to plot maps for selected species by month, year, groups of months or years, long-term means or as time series and contour plots. This study constitutes the first application of an easily accessed and interactive gridded database of plankton abundance in the North Sea. As a further development the MATLAB browser is being converted to a user- friendly Windows-compatible format (WinCPR) for release on CD and via the Web in 2003.

Summarising spatial and temporal information in CPR data

The Continuous Plankton Recorder survey provides pan-oceanic data on geographic distribution, species composition, seasonal cycles of abundance, and long-term change during the last 70 years. In this paper we compare and contrast some of the historic data-analytic protocols of the survey, focusing primarily on the various means by which spatio-temporal information in CPR data has been exposed. Relative strengths and limitations are assessed, followed by suggestions for future approaches to the visualisation and summarising of CPR data.