Lakes - Classification & Monitoring: a strategy for the classification of lakes

This is the report on Lakes – Classification and Monitoring, a strategy for the classification of lakes by the National Rivers Authority. This report describes a scheme for the assessment and monitoring of water and ecological quality in standing waters, greater than about 1ha in area, in England and Wales although it is generally relevant to Northwest Europe. Thirteen hydrological, chemical and biological variables are used to characterize the standing water body in any current sampling. Statistical testing on the chemical variables showed that at least six samples during a year would be needed to produce a representative sampling mean; but in this scheme the choice of variables minimizes logistic cost by not using boat sampling and time costs by not demanding extensive taxonomic work. Standing waters are classified in a state-changed system in which the contemporary values of the variables are compared with a reference baseline state and then placed in categories of percentage change from this baseline. The scheme is presently designed for use at about five year intervals on all lakes greater than 2ha area plus additional lakes of significant amenity or conservation interest.

Wetland resource evaluation and the NRA's role in its conservation. Classification of British wetlands

This is the Wetland resource evaluation and the NRA's role in its conservation: Classification of British wetlands report produced by the National Rivers Authority in 1995. This R&D document provides a clear classification for wetlands in England and Wales. The classification incorporates many of the existing ideas on the subject but avoids some of the problems associated with other classifications. A two-layered 'hydrotopographical' classification is proposed. The first layer identifies situation-types, i.e. the position the wetland occupies in the landscape, with special emphasis upon the principal sources of water. The second layer identifies hydrotopographical elements, i.e. units with distinctive water supply and, sometimes, distinctive topography in response to this. This system is seen as an independent, basic, classification upon which it is possible to superimpose additional, independent classifications based on other features (e.g. base-status, fertility, vegetation, management etc.). Some proposals for such additional classifications are provided.

Body shape variation and colour change during growth in a protogynous fish

Protogynous sequential hermaphroditism is very common in marine fish. Despite a large number of studies on various aspects of sequential hermaphroditism in fish, the relationship between body shape and colour during growth in dichromatic species has not been assessed. Using geometric morphometrics, the present study explores the relationship between growth, body shape and colouration in Coris julis (L. 1758), a small protogynous labrid species with distinct colour phases. Results show that body shape change during growth is independent of change in colour phase, a result which can be explained by the biology of the species and by the social control of sex change. Also, during growth the body grows deeper and the head has a steeper profile. It is hypothesized that a deeper body and a steeper profile might have a function in agonistic interactions between terminal phase males and that the marked chromatic difference between colour phases allows the lack of strict interdependence of body shape and colour during growth.

Seabed classification for trawlability determined with a multibeam echo sounder on Snakehead Bank in the Gulf of Alaska

Rockfishes (Sebastes spp.) tend to aggregate near rocky, cobble, or generally rugged areas that are difficult to survey with bottom trawls, and evidence indicates that assemblages of rockfish species may differ between areas accessible to trawling and those areas that are not. Consequently, it is important to determine grounds that are trawlable or untrawlable so that the areas where trawl survey results should be applied are accurately identified. To this end, we used multibeam echosounder data to generate metrics that describe the seafloor: backscatter strength at normal and oblique incidence angles, the variation of the angle-dependent backscatter strength within 10° of normal incidence, the scintillation of the acoustic intensity scattered from the seafloor, and the seafloor rugosity. We used these metrics to develop a binary classification scheme to estimate where the seafloor is expected to be trawlable. The multibeam echosounder data were verified through analyses of video and still images collected with a stereo drop camera and a remotely operated vehicle in a study at Snakehead Bank, ~100 km south of Kodiak Island in the Gulf of Alaska. Comparisons of different combinations of metrics derived from the multibeam data indicated that the oblique-incidence backscatter strength was the most accurate estimator of trawlability at Snakehead Bank and that the addition of other metrics provided only marginal improvements. If successful on a wider scale in the Gulf of Alaska, this acoustic remote-sensing technique, or a similar one, could help improve the accuracy of rockfish stock assessments.

Marine and estuarine ecosystem and habitat classification

The Ecological Society of America and NOAA's Offices of Habitat Conservation and Protected Resources sponsored a workshop to develop a national marine and estuarine ecosystem classification system. Among the 22 people involved were scientists who had developed various regional classification systems and managers from NOAA and other federal agencies who might ultimately use this system for conservation and management. The objectives were to: (1) review existing global and regional classification systems; (2) develop the framework of a national classification system; and (3) propose a plan to expand the framework into a comprehensive classification system. Although there has been progress in the development of marine classifications in recent years, these have been either regionally focused (e.g., Pacific islands) or restricted to specific habitats (e.g., wetlands; deep seafloor). Participants in the workshop looked for commonalties across existing classification systems and tried to link these using broad scale factors important to ecosystem structure and function.

An objective classification of climatic regions in the Pacific and Indian oceans

We have applied a number of objective statistical techniques to define homogeneous climatic regions for the Pacific Ocean, using COADS (Woodruff et al 1987) monthly sea surface temperature (SST) for 1950-1989 as the key variable. The basic data comprised all global 4°x4° latitude/longitude boxes with enough data available to yield reliable long-term means of monthly mean SST. An R-mode principal components analysis of these data, following a technique first used by Stidd (1967), yields information about harmonics of the annual cycles of SST. We used the spatial coefficients (one for each 4-degree box and eigenvector) as input to a K-means cluster analysis to classify the gridbox SST data into 34 global regions, in which 20 comprise the Pacific and Indian oceans. Seasonal time series were then produced for each of these regions. For comparison purposes, the variance spectrum of each regional anomaly time series was calculated. Most of the significant spectral peaks occur near the biennial (2.1-2.2 years) and ENSO (~3-6 years) time scales in the tropical regions. Decadal scale fluctuations are important in the mid-latitude ocean regions.

A programme to carry out analysis of variance: two-way classification on Micro 2200

A brief description is given of a program to carry out analysis of variance two-way classification on MICRO 2200, for use in fishery data processing.

Genetic status of selected fish taxa in relation to conservation of genetic and species diversity in the Victoria and Kyoga Lake basins

Cichlids are known for their explosive radiation especially in the African Great Lakes marked with a high level of lake endemism. These fishes have been characterized mainly along trophic and habitat differences, by variation in morphological structures such as teeth and jaws and by differences in body shape and coloration. Cichlids are important as a microcosm of macroevolution. The explosive radiation, young evolutionary scale, and the isolation of groups characterized with high levels of endemism and presence of living fossils makes the group important for evolutionary and genetic studies. Lake Victoria region cichlids which are isolated and relatively more recent in evolution were the last to be appreciated in their diversity. Recently Ole Seehausen has found scores of rock fishes in Lake Victoria which were up to then thought to be absent from the Lake and only known to occur in Lakes Malawi and Tanganyika. Greenwood put together the species groups of Lake Victoria, and later in the early 1980's revised the classification of haplochromine species to reflect the phyletic origin and interrelationship of the various groups in Lake Victoria region. Melan Stiassny has been interested in early evolution of cichlids while the likes of Paul Fuerst and Lees Kaufman and Axel Meyer have been interested and are working to explain the speciation mechanisms responsible for the explosive radiation and evolution of cichlids. Locally S.B Wandera and his student Getrude Narnulemo are spearheading the biodiversity and taxonomic studies of cichlids in Lake Victoria region