Changes In Fish Diversity Research Articles

How a multidisciplinary approach involving ethnoecology, biology and fisheries can help explain the spatio‐temporal changes in marine fish abundance resulting from climate change

AbstractAimPredicting the impact of climate change on marine ecosystems or how fish and other species are adapting to rising sea temperatures is still subject to much uncertainty, despite considerable progress in recent years. In this study we assess whether our understanding of the impact of sea warming on marine fish can be enhanced with an interdisciplinary approach that collates data from fisheries, fishermen and scientific research. By doing this, we aim to shed light on the major changes in the abundance and diversity of warm and cold water fish in recent decades in relation to sea warming.LocationThis study was conducted in the north‐western Mediterranean, where the impacts of global warming are particularly critical because range shifts are physically constrained.MethodsWe collected and combined statistical data from fisheries, the traditional ecological knowledge of fishermen (TEK), reproductive data (histological gonad analyses and ichthyoplankton surveys) and extensive research into the relevant literature (including systematic catalogues and museum collections and their databases).ResultsWe have found that changes in the abundance of fish have followed a particular spatio‐temporal sequence, with three different phases of colonization in the case of warm‐water species (occasional occurrence, common presence and establishment), and three phases of regression (abundance reduction, range contraction and disappearance from the catch) in the case of cold‐water species.Main conclusionsOverall, the results show that this multidisciplinary approach, combining qualitative and quantitative information from different sources, provides new insight into the observed changes in fish diversity and abundance in relation to climate change.

Integrating fishermen knowledge and scientific analysis to assess changes in fish diversity and food web structure

In this paper the Ecosystem Approach to Fisheries (EAF) and the Fishermen Knowledge Approach (FKA) were applied to understand changes in a tropical coastal lagoon. Then, the fishermen experience-based knowledge, literature information and data sampling were combined aiming to understand biodiversity loss and food web changing in their fishing environment exposed to the introduction of an invasive fish species. Fishermen indicated the changes in fish species composition and simplification in trophic web, confirming biological data. However they do not attributed changes to the species introduction (our ecological hypothesis previously assumed), but to the sequential construction of bridges that interrupted water flow between the lagoon and the ocean (their environmental hypothesis). This assertion fitted to Ecopath model simulations outputs in which exotic species removal from the ecosystem does not recovery fish composition or the trophic web complexity. Fishermen recalled as larger as smaller species, the matching between food web described by fishermen and the food web from literature and the justification for biodiversity loss presented by fishermen, broadened the confidence on their role as experts. This approach merged the historical views of fishermen and provided evidence on the value of complement scientific data with experts consulting.

Fish diversity in European lakes: geographical factors dominate over anthropogenic pressures

Summary We aimed to distinguish the relative contributions of natural and anthropogenic local factors on patterns of fish diversity in European lakes at different geographical scales. We compiled data from standardised fish monitoring using multimesh benthic gill nets, information on lake morphometry and on geographical, climatic and anthropogenic pressure variables from 1632 lakes in 11 European countries. By means of regression trees, we determined those natural and anthropogenic factors and their thresholds that best predicted local fish diversity, density and mean size. Generalised linear models were used to assess the influence of anthropogenic factors at smaller geographical and morphometric scales. Local fish species richness and diversity were related mainly to morphometric and (bio)geographical/climatic variables. Larger and deeper lakes in warm areas tended to be the most species rich and diverse. Fish density was related mainly to anthropogenically driven productivity but also was sensitive to geographical/climatic factors. Thus, warmer and shallower lower‐altitude European lakes, which are usually more eutrophic, had higher fish densities than cold and deeper higher‐altitude lakes. Fish size increased with altitude and declined with increasing seasonality and temperature. After controlling for the natural factors, productivity had a positive effect on fish species richness and diversity, whereas it negatively influenced fish size. Our results suggest that macroecological patterns of lake fish diversity across Europe are best predicted by natural factors. The contribution of anthropogenic factors to fish diversity was evident only via the effect of eutrophication at smaller geographical scales, whereas no effect could be found from hydromorphological pressures. From an applied perspective, these results suggest that bioassessment and biodiversity evaluation might be most effectively conducted and interpreted locally, where anthropogenic effects on biodiversity become more apparent. At a macroecological scale, the strong effect of environmental temperature on most components of fish diversity suggests future changes in fish diversity as a consequence of climate change.

Effects of littoral habitat complexity and sunfish composition on fish production

Carey MP, Maloney KO, Chipps SR, Wahl DH. Effects of littoral habitat complexity and sunfish composition on fish production. Ecology of Freshwater Fish 2010: 19: 466–476. © 2010 John Wiley & Sons A/S Abstract – Habitat complexity is a key driver of food web dynamics because physical structure dictates resource availability to a community. Changes in fish diversity can also alter trophic interactions and energy pathways in food webs. Few studies have examined the direct, indirect, and interactive effects of biodiversity and habitat complexity on fish production. We explored the effects of habitat complexity (simulated vegetation), sunfish diversity (intra- vs. inter-specific sunfish), and their interaction using a mesocosm experiment. Total fish production was examined across two levels of habitat complexity (low: 161 strands m−2 and high: 714 strands m−2) and two sunfish diversity treatments: bluegill only (Lepomis macrochirus) and bluegill, redear sunfish (Lepomis microlophus), and green sunfish (Lepomis cyanellus) combination. We also measured changes in total phosphorus, phytoplankton, periphyton, and invertebrates to explain patterns in fish production. Bluegill and total fish production were unaffected by the sunfish treatments. Habitat complexity had a large influence on food web structure by shifting primary productivity from pelagic to a more littoral pathway in the high habitat treatments. Periphyton was higher with dense vegetation, leading to reductions in total phosphorus, phytoplankton, cladoceran abundance and fish biomass. In tanks with low vegetation, bluegill exhibited increased growth. Habitat complexity can alter energy flow through food webs ultimately influencing higher trophic levels. The lack of an effect of sunfish diversity on fish production does not imply that conserving biodiversity is unimportant; rather, we suggest that understanding the context in which biodiversity is important to food web dynamics is critical to conservation planning.

The cleaner wrasse, Labroides dimidiatus, is a key organism for reef fish diversity at Ras Mohammed National Park, Egypt

Summary In marine cleaning symbioses, small fish or shrimps remove ectoparasites and other material from cooperating ‘client’ fish. Until now, there has been conflicting evidence with respect to the importance of cleaning for client health and in particular with respect to the impact of cleaning organisms on local fish diversity. Data are provided on the impact of the cleaner wrasse Labroides dimidiatus on reef fish distribution at Ras Mohammed National Park, Egypt. During four field seasons, I regularly sampled fish species composition in 46 reef patches. Natural fluctuations in cleaner fish presence or absence at these reef patches allowed me to assess how this variable correlates with reef fish diversity. In addition, cleaner fish were removed experimentally from some reef patches and added at others to test whether the presence or absence of cleaner fish causes changes in fish diversity. Both cleaner fish disappearance and cleaner fish removal had no immediate effects on fish abundance, i.e. within the first few weeks. A significant decline in fish diversity was only detectable after 4–20 months. In contrast, cleaner immigration or experimental addition led to a significant increase in fish diversity within the first few weeks. Generally, effects were most pronounced for client species that visit reef patches and soon move off again, and less pronounced (but still significant) for resident clients that do not move between reef patches. Surprisingly, the presence or absence of cleaner fish also affected the distribution of resident fish that hardly ever interact with them. This study demonstrates that cleaner fish are a key organism for local reef fish diversity.

Fish Diversity and Growth in Lakes of Aukštaitija National Park

The article presents data on fish community structure and distribution in lakes of Aukstaitija National Park as well as dynamics of quantitative and qualitative parameters of biological indices in those lakes. Investigations were performed in 20 different-sized lakes in 1993–2002. It was established that due to anthropogenic load trophicity of certain small lakes had significantly changed. A total of 26 species representing eight families was recorded in the investigated lakes. Fish communities of the majority of mesotrophic and eutrophic lakes were dominated by roach (Rutilus rutilus L.), on average making up 42% of the number and 30% of the weight of fish caught in a lake, and perch (Perca fluviatilis (L.)), constituting 16% and 4%, respectively. The most intense changes in fish diversity and community structure were recorded in the small lakes Joskutis, Baltys, and Juodenis, previously poisoned with polychlorpinen. In the other lakes, no changes in species diversity were observed in 1960–2002. As a res...

Do human activities raise species richness? Contrasting patterns in United States plants and fishes

AbstractIn a given area, human activities usually cause the extinction of native species and the establishment of non‐native species. A key conservation issue is whether non‐native establishment tends to outpace native species extinction to produce a net gain in species richness. To determine this, empirical data must be accumulated at various scales. I show that, within the United States, the number of established non‐native plant species per state does tend to outpace the number of extinct and threatened species per state. The net gain in plant species is strongly and positively correlated with human population density. Continuation of this trend predicts substantial gains in net plant species richness for all states in the United States as human population grows. This contrasts with freshwater fishes, where most states show a net loss of species diversity as extinct and threatened species exceed established non‐native species. Changes in fish diversity do not correlate strongly with human population or non‐native species but are largely driven by the decline of native fish species.

Episodic Acidification and Changes in Fish Diversity in Pennsylvania Headwater Streams

Current water chemistry and fish communities in 70 Pennsylvania streams were compared with historical records to determine whether fish species richness had declined and, if so, the possible role of acidification. First-, second-, and third-order streams were selected, and stream sites sampled during the 1961–1971 survey were resampled during May and June 1994 in the Appalachian Plateaus province and during June 1995 in the Valley and Ridge province. Streamflow was measured and a habitat assessment was completed at each site. Dominant bedrock types influencing the stream sampling site were determined for the Appalachian Plateaus streams. Episodic water chemistry was collected for 39 of the 50 Appalachian Plateaus streams and 14 of the 20 Valley and Ridge streams during the winter and spring of 1996. Thirty-eight (76%) streams of the Appalachian Plateaus province and 13 (65%) streams in the Valley and Ridge province had a loss of fish species since the 1961–1971 sampling period. Habitat scores were not related to losses of fish species. Of the 53 streams sampled during runoff episodes 22 (42%) increased in total dissolved aluminum by more than 50 μg/L, and 31 (58%) streams decreased in pH by 0.5 units or more. Minnows (Cyprinidae) and darters (Percidae) are sensitive to acidity and were the species most often lost. Streams draining watersheds of the Appalachian Plateaus province dominated by Pottsville bedrock had more acidic water quality during base flow and storm flow sampling periods than streams dominated by Pocono bedrock. The results of this study indicate that many Pennsylvania streams have undergone an alarming reduction in fish diversity during the past 25–34 years. In many of these streams the loss in fish diversity may be attributed to episodic acidification.