The distribution of Corixidae in relation to the water quality of British lakes: A monitoring model

This article is an attempt to devise a method of using certain species of Corixidae as a basis for the assessment of general water quality in lakes. An empirical graphical representation of the distribution of populations or communities of Corixidae in relation to conductivity, based mainly on English and Welsh lakes, is used as a predictive monitoring model to establish the "expected" normal community at a given conductivity, representing the total ionic concentration of the water body. A test sample from another lake of known conductivity is then compared with "expected" community. The "goodness of fit" is examined visually or by calculation of indices of similarity based on the relative proportions of the constituent species of each community. A computer programme has been devised for this purpose.

Littoral vegetation of Lake Tohopekaliga: community descriptions prior to a large-scale fisheries habitat-enhancement project

An extreme dry-down and muck-removal project was conducted at Lake Tohopekaliga, Florida, in 2003-2004, to remove dense vegetation from inshore areas and improve habitat degraded by stabilized water levels. Vegetation was monitored from June 2002 to December 2003, to describe the pre-existing communities in terms of composition and distribution along the environmental gradients. Three study areas (Treatment-Selection Sites) were designed to test the efficacy of different treatments in enhancing inshore habitat, and five other study areas (Whole-Lake Monitoring Sites) were designed to monitor the responses of the emergent littoral vegetation as a whole. Five general community types were identified within the study areas by recording aboveground biomasses and stem densities of each species. These communities were distributed along water and soils gradients, with water depth and bulk density explaining most of the variation. The shallowest depths were dominated by a combination of Eleocharis spp., Luziola fluitans, and Panicum repens; while the deeper areas had communities of Nymphaea odorata and Nuphar luteum; Typha spp.; or Paspalidium geminatum and Hydrilla verticillata. Mineralized soils were common in both the shallow and deep-water communities, while the intermediate depths had high percentages of organic material in the soil. These intermediate depths (occurring just above and just below low pool stage) were dominated by Pontederia cordata, the main species targeted by the habitat enhancement project. This emergent community occurred in nearly monocultural bands around the lake (from roughly 60–120 cm in depth at high pool stage) often having more diverse floating mats along the deep-water edge. The organic barrier these mats create is believed to impede access of sport fish to shallow-water spawning areas, while the overall low diversity of the community is evidence of its competitive nature in stabilized waters. With continued monitoring of these study areas long-term effects of the restoration project can be assessed and predictive models may be created to determine the efficacy and legitimacy of such projects in the future.

Invertebrate communities in northern Lake Victoria, with reference to their potential for fishery production

The zooplankton and macrobenthic communities of Lake Victoria were sampled by lift net and Ponar grab, respectively. The zooplankton comprised copepods and cladocerans, rotifers and aquatic insect larvae. Most taxa exhibited wide distribution in the lake, with the exception of rotifers which were rare in deep offshore waters. The main components in the macro-benthos were chaoborid and chironomid larvae and molluscs. Caridina nilotica (Roux) and other groups were rare in the samples. Zooplankton density ranged from 100000 or more to 4 million ind. m2 and increased from the shallow inshore to deep offshore waters. Numerical dominance of cyclopoids and nauplius larvae was a common feature at all stations sampled. Most macrobenthic taxa were also widely distributed, although chaoborid and chironomid larvae were rare in the samples. Rastrineobola argentea (Pellegrin) and larval Lates niloticus (L.) ate mainly cyclopoid copepods, while cichlids showed a strong preference for adult insects. High ecological stability of the cyclopoids, and the zooplankton community in general, despite radical ecosystem changes in recent years, coupled with what appears to be high predation pressure, offers good prospects for the pelagic fishery in the lake.

Microorganisms of the East African Great Lakes and their response to environmental changes

We have reviewed the phytoplankton composition and succession in the East African Great Lakes, their response to environmental changes, and the communities of microorganisms of the microbial food web. Recent studies in some great lakes, as well as progress in understanding phytoplankton succession and response to environmental factors, enable us to update knowledge of the phytoplankton ecology of these lakes. In particular, we present information indicating that phytoplankton composition in lakes Tanganyika and Kivu may reflect recent changes as a result of global warming or species introduction. We also stress the importance of microbes (at the base of the food web) in these systems and suggest that the microbial food web, which has been mostly overlooked until recently, may play a very large role in determining productivity and nutrient cycling in these large lakes.

Ezagutzaren dinamika Ikas Komunitateetan

[EUS] Laurogeita hamarreko hamarkadan, Eusko Jaurlaritzako Berriztapen Pedagogikoaren Zuzendaritzak eta Bartzelonako Unibertsitateko CREA (Gizarte eta Heziketarako Ikerkuntza Zentroa) ikerkuntza-taldeak Ikas Komunitateen proiektua jarri zuten martxan, elkarlanean, Euskal Autonomia Erkidegoko lau zentrotan. Zentro horiek hezkuntza-proiektu berri bat abiatzeko bidea ematen dute; izan ere, porrot akademiko handia izatearren hautatu dira, ikasle-taldeen aniztasunaren egoerari heltzeko arazo ugari dituztelako edota dauden lekuetan gizarte-bazterkeriarekin loturiko arazo anitz daudelako. Aldi berean, proiektuak eraldaketa proposatzen du, bai eskolarena, baita inguruarena ere, eta, horretarako, eskolako partaide guztiak hartzen ditu kontuan. Emaitza onak ikusi ostean, eta, hezkuntza-berriztapenaren alorrean lehentasuna izanik, ekimena zabaltzen hasi zen hastapeneko zentroez bestelako ezaugarri sozioedukatiboak dituzten eskoletara ere. Esperientzia berritzaile horiek aurrera eramateko gogo handiz agertu ziren, baita ere, «praktika on»en paradigma ez zirenak, eta, emaitzei begiratzen badiegu, dirudienez, etekin onak lortzen ari dira zentroetan. Ikas Komunitateen proiektuak berekin daraman gaitasun eraldatzaileak egokitzeko berezko ahala erakusten du. Egokitzapen horretan, eskolaren —inguruarekin batera— eta proiektuaren arteko sinbiosia lortzen da, hezkuntzako arrakasta- ekintzak sustatuz.

Distribution patterns of tidepool fishes on a tropical flat reef

Rockpools on a tropical f lat reef off the southeastern coast of Brazil were sampled to determine the influence of pool morphometry and water characteristics on fish community structure. The pool closest to the inner fringe of the reef had lower salinity and higher temperature due to inflow of groundwater. The other pools varied only with respect to their morphometric characteristics, algal cover, and bottom composition. Species with a strong affinity for estuarine- like waters characterized the pool closest to the beach and distinguished its fish community from that of the other pools. Instead of being strongly structured by the physicochemical setting and position in the reef, fish communities of the other pools were determined by behavioral preferences and intra- and interspecific interactions. Differences in community structure were related to pool size (the larger sizes permitting the permanency of schooling species), to algal cover (which allowed camouflage for large predatory species), to bottom composition (which provided substrate for turf flora available to territorial herbivores), and to ecological effects (e.g., competition, territoriality, and predation). Although distribution patterns of tidepool fishes have previously been related to the availability of niches, independent of pool position in the reef, our results show synergistic interactions between water properties, presence or absence of niches, and ecological relationships in structuring tidepool fish communities.

Sumilon Island reserve: 20 years of hopes and frustrations

Over 20 years, successive openings and closures of the Sumilon Island marine reserve to fishers have provided unique opportunities to examine the effects of marine reserves on populations and communities of fishes and upon local fisheries. The history of the reserve also highlights the problems and frustrations of educating and convincing people of the need for rational management of renewable marine resources. Yet, it is a symbol of hope in that it has provided a unique example of the potential benefits of marine reserves in fisheries management, particularly in the developing world.

NMFS Cooperative SharkTagging Program, 1962-93: An Atlas of SharkTag and Recapture Data

The National Marine Fisheries Service (NMFS) Cooperative Shark Tagging Program (CSTP) is part of continuing research directed to the study of the biology of large Atlantic sharks. The CSTP was initiated in 1962 at the Sandy Hook Laboratory in New Jersey under the Department of Interior's U.S. Fish and Wildlife Service (USFWS). During the late 1950's and early 1960's, sharks were considered a liability to the economy of resort communities, of little or no commercial value, and a detriment to fishermen in areas where sharks might damage expensive fishing gear or reduce catches of more commercially valuable species.

The Crustacean and Molluscan Fisheries of Honduras

Honduras has many communities of artisanal fishermen who land various species of crustaceans and mollusks, using hands, nets, traps, and free diving from shore and from dugout canoes. It also has industrial fisheries for spiny lobster, Panulirus argus; queen conch, Strombus gigas; and mainly pink shrimp, Penaeus notialis, using traps, scuba divers, and trawl nets.

A baseline assessment of the ecological resources of Jobos Bay, Puerto Rico

This baseline assessment of Jobos Bay and surrounding marine ecosystems consists of a two part series. The first report (Zitello et al., 2008) described the characteristics of the Bay and its watershed, including modeling work related to nutrients and sediment fluxes, based on existing data. The second portion of this assessment, presented in this document, presents the results of new field studies conducted to fill data gaps identified in previous studies, to provide a more complete characterization of Jobos Bay and the surrounding coral reef ecosystems. Specifically, the objective was to establish baseline values for the distribution of habitats, nutrients, contaminants, fi sh, and benthic communities. This baseline assessment is the first step in evaluating the effectiveness in changes in best management practices in the watershed. This baseline assessment is part of the Conservation Effects Assessment Project (CEAP), which is a multi-agency effort to quantify the environmental benefits of conservation practices used by agricultural producers participating in selected U.S. Department of Agriculture (USDA) conservation programs. Partners in the CEAP Jobos Bay Special Emphasis Watershed (SEW) included USDA’s Agricultural Research Service (ARS) and the Natural Resources Conservation Service (NRCS), National Oceanic and Atmospheric Administration (NOAA) and the Government of Puerto Rico. The project originated from an on-going collaboration between USDA and NOAA on the U.S. Coral Reef Task Force. The Jobos Bay watershed was chosen because the predominant land use is agriculture, including agricultural lands adjacent to the Jobos Bay National Estuarine Research Reserve (JBNERR or Reserve), one of NOAA’s 26 National Estuarine Research Reserves (NERR). This report is organized into six chapters that represent a suite of interrelated studies. Chapter 1 provides a short introduction to Jobos Bay, including the land use and hydrology of the watershed. Chapter 2 is focused on benthic mapping and provides the methods and results of newly created benthic maps for Jobos Bay and the surrounding coral reef ecosystem. Chapter 3 presents the results of new surveys of fish, marine debris, and reef communities of the system. Chapter 4 is focused on the distribution of chemical contaminants in sediments within the Bay and corals outside of the Bay. Chapter 5 focuses on quantifying nutrient and pesticide concentrations in the surface waters at the Reserve’s System-Wide Monitoring Program (SWMP) sites. Chapter 6 is a brief summary discussion that highlights key findings of the entire suite of studies.

Does the California market squid (Loligo opalescens) spawn naturally during the day or at night? A note on the successful use of ROVs to obtain basic fisheries biology data

The California market squid (Loligo opalescens Berry), also known as the opalescent inshore squid (FAO), plays a central role in the nearshore ecological communities of the west coast of the United States (Morejohn et al., 1978; Hixon, 1983) and it is also a prime focus of California fisheries, ranking first in dollar value and tons landed in recent years (Vojkovich, 1998). The life span of this species is only 7−10 months after hatching, as ascertained by aging statoliths (Butler et al., 1999; Jackson, 1994; Jackson and Domier, 2003) and mariculture trials (Yang, et al., 1986). Thus, annual recruitment is required to sustain the population. The spawning season ranges from April to November and spawning peaks from May to June. In some years there can be a smaller second peak in November. In Monterey Bay, the squids are fished directly on the egg beds, and the consequences of this practice for conservation and fisheries management are unknown but of some concern (Hanlon, 1998). Beginning in April 2000, we began a study of the in situ spawning behavior of L. opalescens in the southern Monterey Bay fishing area.

Social and economic implications of the fishery distribution patterns on Lake Victoria, Uganda

The fisheries of Lake Victoria have undergonea dramatic transformation during the last two decades. From being a locally based fishery with little intervention and capital investment from outside,the present fishery is dominated by national and international capital penetrating the industry. It is explosion in the growth of nile perch and the strong demand devloped for this fishin the global markets, which have transformed the fisheries of the Lake victoria. This report presents the results of a survey carried out between October 2001 and February 2002 about the fishery distribution patterns and their impacts on fisher communities of Lake Victoria. The fisheries distribution pattern of the lake is described as well as the flows and benefits from the fisheries resource and the resource constraints and sustainability options. A major part of the paper discusses some of the socio-economic impacts of the rapid changes that are responsible for the present fisheries. It particularly focuses on the effect of the Nile perch boom, its globalization and the development of the fish industry in Uganda, on food security and employment for the local population.

Sanitation, fish handling and artisanal fish processing within fishing communities: socio-cultural influences

postive transformation of the fisheries sector in Uganda has of recent been scatted by failure to mountain fish quality and safety,akey prerequiste for retaining and gaining fish markets. The social cultural study established the extent to which social cutural practices had affected the levels and the use of sanitation facilities,fish handling facilities and artisanal fish processing techniques and the factors that influenced these practices in the fishing communities of lake victoria. This information is of significance for the purpose of advocacy and mobilization of fishers in order to improve sanitation, fish handling and artisanal fishing processing situation in the fishing communities.

Molecular identification of symbiotic dinoflagellates (Zooxanthellae) of dominant reef-building corals off Kish Island

Scleractinian coral species harbour communities of photosynthetic taxa of the genus Symbiodinium. As many as eight genetic clades (A, B, C, D, E, F, G and H) of Symbiodinium have been discovered using molecular biology. These clades may differ from each other in their physiology, and thus influence the ecological distribution and resilience of their host corals to environmental stresses. Corals of the Persian Gulf are normally subject to extreme environmental conditions including high salinity and seasonal variation in temperature. This study is the first to use molecular techniques to identify the Symbiodinium of the Iranian coral reefs to the level of phylogenetic clades. Samples of eight coral species were collected at two different depths from the eastern part of Kish Island in the northern Persian Gulf. Partial 28S nuclear ribosomal (nr) DNA of Symbiodinium (D1/D2 domains) were amplified by Polymerase Chain Reaction (PCR). PCR products were analyzed using Single Stranded Conformational Polymorphism (SSCP) and phylogenetic analyses of the LSU DNA sequences from a subset of the samples. The results showed that Symbiodinium populations were generally uniform among and within the populations of 8 coral species studied, and there are at least two clades of Symbiodinium from Kish Island. Clade D was detected from 8 of the coral species while clade C90 was found in 2 of species only (one species hosted two clades simultaneously). The dominance of clade D might be explained by high temperatures or the extreme temperature variation, typical of the Persian Gulf.

Benthic community survey of Gwadar (east bay) Balochistan, Pakistan

Benthic communities of the Gwadar east bay (Balochistan) was surveyed during the onset of S.W. monsoon. A total 1030 specimens were collected which represented Phyla of Arthropoda, Mollusca, Annelida, Echinodermata. The most abundant class observed was that of Bivalvia. Seawater parameters such as dissolved oxygen, temperature, pH, salinity together with sediment characteristics were measured. Analysis of variance between observed stations and fauna do not show any significant difference (P<0.05). The present observation forms a baseline study in the area.