A tale of two habitats: preliminary comparison of fish abundance and diversity between saltmarsh- and mangrove-dominated creeks in the Nahoon Estuary, South Africa

2019 ◽  
Vol 41 (4) ◽  
pp. 449-454 ◽  
Author(s):  
R Keur ◽  
N James ◽  
A Rajkaran
Keyword(s):  
South Africa ◽  
Fish Abundance ◽  
Preliminary Comparison ◽  
Abundance And Diversity

scholarly journals The abundance, diversity and distribution of small fishes in mangrove and non-mangrove estuaries in warm temperate South Africa

2018 ◽  
Vol 82 (2) ◽  
pp. 81 ◽  
Author(s):  
Steven McGregor ◽  
Nadine A. Strydom
Keyword(s):  
South Africa ◽  
Fish Abundance ◽  
Fish Conservation ◽  
Ecological Services ◽  
Nursery Areas ◽  
M 12 ◽  
Abundance And Diversity ◽  
Fish Survival ◽  
Warm Temperate

Mangroves in tropical and subtropical regions have been well documented in terms of the advantages they provide and their role in structuring ichthyofaunal assemblages, but little is known about their warm temperate counterparts. The study aimed to investigate the importance of warm temperate mangroves by comparing the abundance, diversity and distribution of small fishes in mangrove and non-mangrove estuaries in warm temperate South Africa. A 50x2 m (12-mm mesh) seine net was used over three summer seasons to sample small fishes in the Gonubie, Qora, Nahoon and Xhora estuaries (the latter two being mangrove estuaries). Fish abundance and diversity showed little variation among estuaries, despite the presence of mangroves. Estuaries in warm temperate areas are not only at the edge of mangrove distribution, but also offer alternative habitats which lend similar advantages to fish survival. It appears that warm temperate ichthyofauna have not yet evolved a dependence on mangrove systems in terms of the food, refuge and other ecological services they provide. Understanding the function of habitats and their value in enhancing fish survival in estuarine nursery areas is essential for fish conservation.

Community dynamics in Fijian coral reef fish communities vary with conservation and shark-based tourism

2019 ◽  
Vol 25 (4) ◽  
pp. 363
Author(s):  
Mallory G. McKeon ◽  
Joshua A. Drew
Keyword(s):  
Community Dynamics ◽  
Local Community ◽  
Census Data ◽  
Fish Abundance ◽  
Full Potential ◽  
Community Members ◽  
Composition And Structure ◽  
Feeding Methods ◽  
Abundance And Diversity ◽  
Unprotected Area

Marine protected areas (MPAs) effectively improve the biomass and diversity in heavily exploited marine systems, but often fail to reach their full potential because they require more space, time, and consistency of regulation. Recently, shark-based tourism, which utilises some of the remaining shark strongholds as tourism hotspots, has brought about increased awareness to exploited reef systems. In Fiji, specifically, shark diving companies include local community members in their operations to promote better understanding of their reefs. We seek to investigate whether seemingly denser shark populations during feeding times influence community composition and structure. Visual census data were collected from 50-m belt transects at four different reefs in Fiji: two MPAs with shark-based ecotourism with food provisioning, one MPA without shark-based ecotourism, and one unprotected area without shark-based tourism. Paradoxically, indices of evenness and diversity were highest in the non-protected site. However, there was significantly higher fish abundance and species diversity within reserves than outside of reserves. Within reserves, sites with shark feeding had lower fish abundance and higher richness, diversity, and evenness. Mean trophic level was highest at sites with shark feeding. Use of chum increased average fish abundance and diversity within shark-dive sites. These results indicate that there are evident differences between MPAs that do and do not offer trophic supplementation for shark-based ecotourism. Thus, tourism may be facilitating a shift of ecosystem composition in such areas. Furthermore, the results suggest that feeding methods may augment the impacts of shark-based tourism on the reef at large.

Comparative cleaning behaviour of Pederson's cleaner shrimp (Ancylomenes pedersoni) between geographically close yet ecologically dissimilar coral reef habitats

2020 ◽  
Vol 100 (7) ◽  
pp. 1093-1106
Author(s):  
Joseph J. Romain ◽  
Dan A. Exton ◽  
David J. Smith ◽  
Amelia Rose ◽  
Clayton Vondriska ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Cover ◽  
Fish Population ◽  
Fish Abundance ◽  
Environmental Drivers ◽  
Variable Nature ◽  
Total Fish ◽  
Abundance And Diversity ◽  
Lutjanus Apodus ◽  
Cleaner Shrimp

AbstractCleaning mutualisms are important interactions on coral reefs. Intraspecific variation in cleaning rate and behaviour occurs geographically and is often attributed to local processes. However, our understanding of fine-scale variation is limited, but would allow us to control for geography and region-specific behavioural patterns. Here, we compare the cleaning activity of Pederson's cleaner shrimp (Ancylomenes pedersoni) on two neighbouring, yet ecologically dissimilar, reef systems in Honduras: Banco Capiro, an offshore bank close to significant land runoff with high coral cover but a depleted fish population, and an oligotrophic fringing reef around the island of Utila, with lower coral cover but high fish abundance and diversity. The proportion of realized to potential fish clientele was <60% at both sites, and the composition of clientele was neither reflective of the demographics of the resident assemblages at each site nor similar between sites. Parrotfishes represented 13–15% of total fish abundance at both sites yet accounted for >50% (Banco Capiro) and 10% (Utila) of all cleans. Conversely, the schoolmaster snapper (Lutjanus apodus) represented ~1% of total fish abundance at both sites yet accounted for 40% (Utila) and 1% (Banco Capiro) of all cleans. After standardizing our cleaning rate data by clientele abundance, we find that clientele at Banco Capiro engage in over four times as many cleaning encounters per hour with A. pedersoni than at Utila. Our study highlights the variable nature of coral reef cleaning interactions and the need to better understand the ecological and environmental drivers of this biogeographic variation.

Lure-assisted visual census: a new method for quantifying fish abundance, behaviour, and predation risk in shallow coastal habitats

2010 ◽  
Vol 61 (12) ◽  
pp. 1349 ◽  
Author(s):  
Claudia Kruschel ◽  
Stewart Schultz
Keyword(s):  
Predation Risk ◽  
Structural Complexity ◽  
Marine Ecology ◽  
Fish Abundance ◽  
Coastal Habitats ◽  
Field Methods ◽  
Bare Sediment ◽  
Faunal Abundance ◽  
Abundance And Diversity ◽  
Ambush Predators

Understanding the causes of variation in faunal abundance and diversity across shallow coastal habitats is a fundamental goal of marine ecology. Field methods for inferring a habitat effect on population density and predation risk are informative only if method biases are equal across habitats and species. We hypothesised that observation of fixed lures has a species by bias interaction if sampled species have different modes of predation, and that these biases are overcome by use of moving lures. We tested this hypothesis by observation of fixed and moving lures within seagrass and bare sediment in the Novigrad Sea, Croatian Adriatic. Both methods showed that ambush predators peaked in seagrass, wait–chasers peaked over bare sediment, and move–chasers were abundant in both. Stationary lures underestimated wait–chase and wait–ambush predators relative to moving lures, whereas moving lures did not underestimate the density of predators. These results indicate that stationary lures can underestimate both fish abundance and predation risk in the presence of waiting predators, and that if waiting predators are more abundant in structured habitat, then stationary lures will underestimate the predation risk within such habitats. Use of moving lures may be preferable for comparing habitats differing in structural complexity and frequency of predation modes.

scholarly journals Comparing the Performance of Protected and Unprotected Areas in Conserving Freshwater Fish Abundance and Biodiversity in Lake Tanganyika, Tanzania

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Emmanuel Andrew Sweke ◽  
Julius Michael Assam ◽  
Abdillahi Ismail Chande ◽  
Athanasio Stephano Mbonde ◽  
Magnus Mosha ◽  
...  
Keyword(s):  
Protected Areas ◽  
Marine Protected Areas ◽  
Lake Tanganyika ◽  
Species Turnover ◽  
Environmental Parameters ◽  
Fish Abundance ◽  
Mahale Mountains National Park ◽  
Baseline Information ◽  
Abundance And Diversity ◽  
Management Approaches

Marine protected areas have been shown to conserve aquatic resources including fish, but few studies have been conducted of protected areas in freshwater environments. This is particularly true of Lake Tanganyika, Tanzania. To better conserve the lake’s biodiversity, an understanding of the role played by protected areas in conserving fish abundance and diversity is needed. Sampling of fish and environmental parameters was performed within the Mahale Mountains National Park (MMNP) and nearby unprotected areas at depths between 5 m and 10 m. Twelve replicates of fish sampling were performed at each site using gillnets set perpendicularly to the shore. Mann-Whitney tests were performed, and the total amount of species turnover was calculated. A total of 518 individual fish from 57 species were recorded in the survey. The fish weight abundance was fivefold greater in the MMNP than in the unprotected areas. Fish abundance and diversity were higher in the MMNP than in the unprotected areas and decreased with distance from it. Our findings confirmed the importance of the protected area in conserving fish resources in Lake Tanganyika. The study provides baseline information for management of the resources and guiding future studies in the lake and other related ecosystems. Management approaches that foster awareness and engage with communities surrounding the MMNP are recommended for successful conservation of the resources in the region.

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